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Injuries or emergent conditions involving the reproductive tract are common in equine practice, and initial care measures can play a substantial role in determining short- and long-term outcomes.
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Interventions for the various injuries of the male external genitalia have in common the goal of mitigating inflammation and edema, preventing secondary problems from dependent positioning, and preserving neurologic function.
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Placentitis does not represent a life risk for the dam but is an emergency condition for the fetus; foals should be considered at risk for sepsis and encephalopathy after birth, and monitored accordingly.
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Hydropsic conditions can be detected and monitored sonographically, and elective controlled reduction of the voluminous fluid is often the intervention of choice.
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Uterine torsion can be challenging to definitively diagnose and manage in the field.
Introduction
In the gamut of reproduction-related emergency conditions in horses, dystocia in the mare may be the problem most familiar to equine veterinarians and horse owners—the specter of birth-related problems rightfully elicits much preparation and client education from veterinarians to recognize and prepare for parturition-related emergencies—but there are many other conditions affecting the reproductive tract that also represent significant problems in which timely intervention is imperative. As with emergencies involving any other organ system, minimizing the time to diagnosis and intervention is key to a positive outcome. Therefore, the ability to recognize and intervene in these conditions is an important part of the knowledge base for veterinarians whose practice includes breeding animals. This article will review guidelines for managing selected emergency conditions involving the reproductive tract in stallions, and that involve the external portion of the tract or arise during gestation in mares. The goal is to help prepare the veterinarian to recognize and confidently undertake or at least initiate effective interventions for these problems in the field.
Conditions of the External Portion of the Reproductive Tract of Mares
Injury of the vestibule and vagina
Lacerations of the vagina, transverse fold, and vestibule most commonly occur during breeding and foaling. The vulva and vestibule are also an occasional site of injury from kicking wounds from other mares; the hind foot of the kicking mare can abrade and lacerate the vulva and enter the vestibule and tear the mucosa (Fig. 1). Mares found with vulvar injury should be examined to determine whether abrasion or laceration extended into the vestibule.
Fig. 1Mare with vulval injury that extends into and involves the vestibule.
(Courtesy of Dr. Peter Morresey, BVSc MVM MACVSc DipACT DipACVIM CVA, Kentucky.)
and should prompt immediate examination. Blood in a dismount sample may also originate from an episiotomy performed in the mare to facilitate breeding. Breeding injury often takes the form of laceration of the cranial part of the vagina, in the dorsolateral aspect of the wall near the cervix, but may also also result in full-thickness rupture of the wall or laceration of the uterine wall.
Methods of examining the vagina and vestibule include manual palpation; visualization of the tract through a disposable or glass speculum as it is gradually withdrawn from the cervix to the vestibule; evaluation with a Caslick speculum, which can allow a broader visual field, especially of the cranial extent of the vagina; and use of an endoscope that is passed manually or through a speculum.
If vaginal injury is suspected after a live breeding, initial evaluation can be performed with a speculum or endoscope to confirm a lesion and site. Injuries involving only the mucosa or submucosa often heal spontaneously. Injuries that appear suspicious for deeper penetration may be best evaluated with a scrubbed and disinfected bare hand, lubricated with sterile jelly, and slowly and gently advanced into the vagina for careful digital exploration in the adequately restrained mare. Deep lacerations or full-thickness tears in the cranial aspect of the vagina are likely to open into the peritoneal cavity and warrant immediate emergency care, including administration of antimicrobials and a nonsteroidal anti-inflammatory drug (NSAID), and preparation or referral for surgery, if possible.
Diagnostic workup for peritonitis, and monitoring for it over the next several days, with peripheral blood testing, sonographic imaging, or abdominocentesis is also indicated (see section on uterine rupture in the accompanying article in this issue). It should be kept in mind that deep lacerations or near-ruptures that approach but do not actually penetrate the serosal surface can still facilitate translocation of bacteria and induce peritonitis and the same clinical changes as a true perforation. Vaginal lacerations and perforations arising caudal to the peritoneal reflection can be managed with medical treatment and second-intention healing. In one report
Gomez JH, Rodgerson DH, Goodin J. How to repair cranial vaginal and caudal uterine tears in mares. In Proceedings. San Diego, CA: 54th Ann Conv Amer Assoc Equine Pract 2008; 54:295–7.
of cranial vaginal lacerations and caudal uterine lacerations repaired with the mare in a Trendelenburg position, 5 of 8 mares with vaginal laceration recovered, whereas 2 of 4 mares with uterine lacerations were euthanized because of severe, diffuse peritonitis. If the equipment and technical support are available on site for general anesthesia and hoisting the mare’s hindquarters into the Trendelenburg position, this surgery can be performed in the field if surgical expertise is available.
Lacerations in the cranial part of the vagina can also arise as a foaling injury, with clinical signs appearing in the postpartum period and ranging from mild, bloody vaginal discharge to peritonitis and intestinal evisceration through the vagina or vulva. Mares with bloody discharge and signs of systemic illness (depression, pyrexia, strong digital pulses) should not have uterine lavage until they have been examined to rule out a vaginal or uterine perforation.
Summary: Suspicion of a vaginal injury should prompt visual evaluation of the tract to locate a lesion, and possibly manual evaluation to determine the site and depth of the injury. Deep lacerations of the uterus or cranial part of the vagina carry a risk of communicating with the peritoneal cavity; these wounds and outright perforation should be sutured and the mare treated with broad-spectrum antimicrobials and anti-inflammatories while being monitored for peritonitis. Caudal lacerations or perforations may be manageable with medical treatment.
Conditions of the External Portion of the Stallion Reproductive Tract
Traumatic injury of the external genitalia
Scrotal and testicular injury
Traumatic injury of the external genitalia in a stallion is considered a reproductive emergency because prompt intervention is required to reduce damage to fertility or breeding ability. Most such injuries arise during breeding from a kick by a mare,
but stallions can also sustain injury to this area while attempting to jump a fence or by impaling accidents at pasture. Scrotal swelling, asymmetry, or heat, skin abrasion or laceration, and pain upon palpation make the diagnosis visually straightforward. In addition to traumatic orchitis, less-acute causes of testicular inflammation, such as septic orchitis,
may also be considered emergent in nature once they are noticed in a breeding stallion, because of the need to quickly and effectively reduce scrotal inflammation in the interest of preserving fertility.
Direct blows to the scrotal area result in a gamut of severity: blunt trauma may cause testicular contusion and associated edema, may disrupt the parietal layer of the tunica vaginalis and result in hydrocele or hematocele (Fig. 2), or may penetrate the tunica albuginea and directly damage testicular parenchyma, including causing testicular rupture.
The third severity can lead to disruption of the blood-testis barrier and exposure of seminiferous tubule contents to the circulation, causing the downstream complication of immune-mediated orchitis as a threat to future fertility.
Fig. 2Transcutaneous sonogram of testicular hydrocele in a stallion following previous traumatic injury in the scrotal area. Notice the strands of fibrin extending from the surface of the testicle to the parietal layer of the tunic.
The immediate goals in managing traumatic scrotal and testicular injury are reducing swelling and attenuating the inflammatory response that will develop in response to the trauma. Administration of a NSAID and local application of a cold pack are important first-aid measures. Nonsteroidal anti-inflammatory medications (flunixin meglumine, 1.1 mg/kg, intravenously [IV] or orally or phenylbutazone, 4.4 mg/kg, IV or orally) pharmaceutically attenuate the prostaglandin release and cytokine cascade that are activated upon traumatic injury and lead to increased blood flow, local vascular leak, and pain in the injured tissue. An NSAID should be continued for as long as clinically dictated by the severity of injury and response to treatment. The edema or hemorrhage in the scrotum may preclude precise determination of injury by means of palpation; diagnostic ultrasonography is very useful in aiding the examiner to determine the nature, location, and extent of injury inside the scrotum, as well as the response to treatment and development of delayed complications such as formation of adhesions.
Cold application is an effective countermeasure for inflammation. Cold application can be started with hydrotherapy, but use of a sling to hold a cold pack in place and provide prolonged contact between it and the scrotal area is a superior method of reducing local tissue temperatures and inflammation.
Depending on the severity of injury, additional treatments should encompass broad-spectrum systemic antimicrobials, furosemide, and topical wound treatments as parts of the treatment regimen. Corticosteroids can be used as an additional source of anti-inflammatory activity and are warranted in an animal with immune-mediated orchitis, but should be used with care in stallions, particularly individuals with confirmed or phenotypic metabolic syndrome. Intentional sexual stimulation should be avoided in the initial period following the injury; stallion rings or any other device to discourage masturbation should not be used.
The sequelae of ineffective inflammation and temperature control in testicular trauma can include decreased semen quality in the future. Trauma induces edema and swelling that effectually insulate the testicles and impair fertility. Even a transient period of increased temperature can reduce spermatogenesis for 60 days.
serial sperm chromatin structure assays were used to evaluate the effect of scrotal heat stress on spermatozoal DNA content. Scrotal heat was created by applying a plastic-coated wool covering for 48 hours, which resulted in a 2- to 3-degree increase in scrotal temperature. The susceptibility of spermatozoal DNA to denaturation was dependent on the spermatogenic cell stage that the ejaculated sperm were in at the time of the heat stress, with the spermatid, late primary spermatocyte stage, and early primary spermatocyte stages being the most susceptible.
fine-needle testicular aspirates were used to follow testicular function following severe trauma of the penis, prepuce, and scrotum in a stallion. Aspirations were performed under sedation with a 22-gauge needle connected to a 10-mL syringe. The first aspirate was obtained 1 month after the injury, and the second aspirate was obtained 1 month later. The first aspirate revealed testicular degeneration, with observation of chiefly primary spermatocytes with a few late-stage spermatids and spermatozoa and an increased Sertoli cell-to-germ cell ratio. Macrophages were also seen in the first sample. The second aspirate revealed a marked decrease in Sertoli cell-to-germ cell ratio and an increase in early and late spermatids, findings consistent with improvement. Giant multinucleated cells were seen in both aspirates, consistent with heat-associated testicular inflammation and degeneration. The stallion of that report was able to breed and settle mares 2 months after the second aspirate.
Penile injuries
Injuries of the penis most often arise during live-cover breeding, in the form of blunt trauma from a kicking mare, sudden movement by the mare during coitus, or laceration from the mare’s tail hairs stretched across the vulva. The engorged penis can also be inadvertently bent during semen collection with an artificial vagina (AV) or during mounting of the phantom. Clinical signs of swelling, heat, and pain are usually quickly apparent, but sometimes may not manifest for a period of hours to days after breeding (Fig. 3). Hematomas form if there is disruption of the venous plexuses running along the dorsal aspect of the penis and can arise anywhere along the shaft of the penis.
Fig. 3Penile injury with secondary swelling and paraphimosis in a stallion.
(Courtesy of Dr. Peter Morresey, BVSc MVM MACVSc DipACT DipACVIM CVA, Kentucky.)
The basic first aid measures are similar to those discussed for scrotal injury and are aimed at reducing swelling: application of cold through cold-water hosing or compression with a covered ice pack and administration of an NSAID medication. These should be initiated as quickly as possible. Other helpful measures are massage of the swollen tissue, applying a length of stockinette to the penis to provide continuous compression support, administration of a diuretic, topical application of a hydrophilic agent (glycerin) or osmotic agent (mannitol, sugar) to reduce edema, topical and systemic antimicrobials if there is a wound, and application of a nonirritating emollient (nitrofurazone, petroleum jelly) to protect the exposed penile epithelium. Penile skin quickly becomes inflamed and excoriated with exposure, and cracking of the epidermis facilitates infection and further inflammation with eventual fibrosis. If the penis can be pushed back through the preputial orifice into the external preputial fold, placement of a purse-string suture at the orifice will retain the penis there temporarily in a physiologic position and the prepuce will help provide counterpressure. If the preputial area is also injured and abraded or edematous, the tissue will be friable and placement of a purse-string suture is not indicated. An alternative to this technique is using a penile repulsion (probang) device to maintain the penis inside the prepuce, using easily obtainable materials.
Koch C, O’Brien T, Livesey MA. How to construct and apply a penile repulsion device (Probang) to manage paraphimosis. In Proceedings, Las Vegas, NV: 55th Ann Conv AAEP, 2009; 338–41.
If the horse cannot retract the edematous penis and it cannot be manually repelled into the prepuce, it should be supported against the abdomen with a sling to prevent dependent edema from exacerbating the initial swelling. Continuation of an NSAID, daily hosing, massaging, and light exercise through hand walking will aid resorption of edema. Failure to effectively resolve edema and enable retraction of the penis will result in progressive edema, fatigue of the penile retractor muscle, and stretch injury of the pudendal nerves, which lead to the inability to self-correct and paraphimosis. As with scrotal injuries, ultrasound imaging is helpful in identifying the internal nature and extent of penile injuries
and for objectively monitoring response to treatment.
Summary: Quick administration of NSAIDs and cold application are the first-line treatments to attenuate swelling and control pain. Manual massage, application of external compression, application of topical emollients to aid in reducing edema and protect the penile epidermis, and prevention of additional edema secondary to dependent positioning are also necessary.
Priapism
Priapism refers to vascular penile engorgement not arising from sexual stimulation. Priapism has been categorized as high flow or low flow, from either excessive arterial inflow through an arteriovenous communication or decreased venous outflow of blood from the cavernosus, respectively. In horses, priapism is nearly always low flow, or veno-occlusive, in etiology.
Unmitigated priapism can progress into paraphimosis. In horses, priapism can also occur secondary to administration of a phenothiazine-derivative tranquilizer such as acepromazine, although in the past it was associated with propriopromazine. Priapism has also been reported following general anesthesia, neoplasia, and nematodiasis.
Priapism can present as persistent, full, penile erection or as partial erection with persistent protrusion of only part of the penis from the prepuce, with palpable turgidity of the corpus cavernosum.
Acetylcholine antagonists can be used in the short term when priapism is the result of α-adrenergic blockade such as following administration of acepromazine. The use of benztropine mesylate (8 mg/average-sized horse, given slowly IV) has been described.
Other drugs that may be useful for treatment of priapism include terbutaline and clenbuterol, beta-specific agonists that cause vasodilation and are thought to improve venous outflow from the corpus cavernosum.
Injection of alpha-1-selective agonist phenylephrine (10 mg phenylephrine diluted in saline solution to a concentration of 1 mg/mL) into the corpus cavernosum can be effective for reducing priapism. A single treatment may be efficacious in acute cases. This treatment may only be effective for several hours in chronic cases.
Irrigation of the corpus cavernosum with heparinized saline (10 units/mL) to flush out sludged erythrocytes and thrombotic material may be necessary in cases that do not respond to medical treatment. With the horse under anesthesia, heparinized saline is instilled under pressure through a 12- or 14-gauge needle introduced into the corpus cavernosum just proximal to the glans penis, and the saline is drained through a similarly placed needle or stab incision made 10 to 15 cm distal to the ischium until fresh hemorrhage is present in the effluent. Phenylephrine can also be infused following irrigation.
Erection that persists following irrigation suggests that venous outflow remains occluded, whereas arteriolar inflow continues. This situation may warrant a corpus cavernosum penis shunt through the corpus spongiosum penis.
The term paraphimosis refers to the condition of being unable to retract the penis because it is paralyzed, it has become engorged and enlarged secondary to hanging in an extended position and will not fit through the preputial orifice, or the prepuce has become edematous and swollen to the extent that it cannot accommodate retraction of the penis. The most common cause is traumatic injury to the genital area, with preputial swelling that reduces the preputial opening size. In addition to traumatic injury, neurologic injury or any other condition that leads to prolonged penile protrusion and dependent positioning has the potential to result in paraphimosis. Known causes include severe bodily debilitation, herpesvirus 1 infection, rabies, purpura hemorrhagica, unresolved priapism, inguinal abscess, and systemic hypo-oncotic conditions, among others.
Administration of tranquilizers of the phenothiazine class, notably acepromazine, has been linked to the development of paraphimosis. This development occurs as a result of α-adrenergic receptor blockade; blockade of α receptors may directly block activity in the motor neurons supplying the retractor penis muscle and may also prevent vasoconstriction of the arterial vasculature delivering blood to the corpus cavernosum, impairing detumescence.
Whatever the initial insult, once the penis has dangled in a ventral and unretracted state for a brief period of time, venous and lymphatic return are impaired and the organ will grow increasingly edematous. Progressive swelling makes the problem more dire by exacerbating the penile size and heft, decreasing the likelihood that the retractor muscles can return the penis to the prepuce, even if they have normal innervation and function. In long-standing cases, chronic stretching of the internal pudendal nerves can result in permanent paralysis and the need for surgery to amputate a portion of the penis.
Recognition of paraphimosis is visually straightforward (see Fig. 3). Measures to reduce edema should immediately be started, whatever the cause. Intervention is the same as described for traumatic injury of the externa genitalia at the beginning of the article. External compression with an Esmarch bandage or other means,
manual massage, application of ice packs, administering anti-inflammatory drugs, topical application of osmotic agents and emollients to protect the penile skin, and preventing progression of swelling by replacing and retaining the penis in the prepuce or holding it up against the body wall with a sling are all helpful. A recent case study
described favorable results with the novel use of a 5-L fluid bag compression device to provide external compression to stallions with paraphimosis.
Conditions arising during gestation
Placentitis
Placentitis can be considered a reproductive emergency because prompt intervention may improve the outcome for the mare and foal, especially if the intervention is initiated early in the disease process. In most instances, it can be recognized through physical examination and ultrasonography and appropriately managed on the farm. Placentitis is a common infectious cause of abortion and perinatal foal mortality. Nearly 25% of placentas from aborted, stillborn, or premature foals examined over a 2-year period at one diagnostic laboratory had evidence of placentitis, and nearly one-third of 3514 aborted fetuses, stillborn foals, and foals that died less than 24 hours after birth were associated with placentitis.
Most cases of placentitis are caused by bacteria ascending from the vulva or vagina and breaching the cervical barrier to colonize the caudal pole of the chorioallantois, at the cervical star. Mares may have acquired anatomic conditions of the caudal part of the reproductive tract that permit introduction of bacteria into the tract, such as pneumovagina or vaginovestibular reflux, or may have conditions that impair the integrity of the tract’s normal barriers, such as cervical tears, adhesions, or fibrosis.
Placentitis can take one of several clinical manifestations. Chronic, late-gestational placentitis most commonly causes focal disease, with lesions located at the cervical star.
However, bacterial placentitis can also manifest acutely, with either focal or diffuse placental lesions. This form of placentitis is the type most associated with fetal bacteremia and most frequently found in the placenta from fetuses aborted before or around midgestation.
In contrast, placentitis caused by nocardioform actinomycetes causes no changes at the cervical star, but rather a focal to focally extensive placentitis at the base of the uterine horns or the juncture between the horns and uterine body, with accumulation of mucoid exudate causing a plane of separation between the fetal membranes and endometrium (Figs. 4 and 5).
Fig. 4Placenta from mare with nocardioform placentitis. Notice the diffuse nature of the thickening and tan discoloration in the pregnant horn (bottom) along its length and at its junction with the body.
Fig. 5Transabdominal sonogram of the uterus and placenta in a mare with nocardioform placentitis. The image was obtained in the pregnant horn; an area where hypoechoic exudate is accumulating (asterisk) and creating separation between the endometrium and chorioallantois (arrow) is seen.
Major causative pathogens in one large study included Streptococcus zooepidemicus, Leptospira spp, Escherichia coli, nocardioform actinomycetes, fungi, Pseudomonas aeruginosa, Streptococcus equisimilis, Enterobacter agglomerans, Klebsiella pneumoniae, and α-hemolytic Streptococcus.
Fungal organisms generally induced focally extensive placentitis at the cervical star, usually observed in late gestation, with Aspergillus spp being the most common organism isolated.
The inflammation caused by infection is an important cause of abortion in ascending placentitis. Colonization of the placental tissues with bacteria causes upregulation of proinflammatory mediators (interleukin [IL]-6 and IL-8) and increased prostaglandin production, immune cell infiltration, and placental thickening at the site of infection. In an ascending placentitis model induced by cervical inoculation of S zooepidemicus, inflammation was seen at the cervical star and in the umbilical cord and amnionic fluid.
Premature delivery in ascending placentitis is associated with increased expression of placental cytokines and allantoic fluid prostaglandins E2 and F2α.
Premature birth was not always associated with fetal bacterial infection, and not all mares with placentitis had clinical signs or placental pathology. High concentrations of allantoic fluid prostaglandin E2, and prostaglandin F2α were detected within the 48 hours preceding abortion or delivery.
Premature delivery in ascending placentitis is associated with increased expression of placental cytokines and allantoic fluid prostaglandins E2 and F2α.
Proinflammatory cytokines in the chorioallantois, amnionic fluid, endometrium, cervix, and fetal tissues were higher in the experimentally infected mares, compared with controls.
Premature delivery in ascending placentitis is associated with increased expression of placental cytokines and allantoic fluid prostaglandins E2 and F2α.
The placental infection, although typically not affecting the dam, results in an infectious, proinflammatory gestational environment that can lead to impaired fetal growth, fetal sepsis, and early parturition or abortion.
Clinical Signs
The most common clinical signs of placentitis are premature mammary development or appearance of mammary secretions, vulvar discharge, ligamentous relaxation around the tail head, and abortion. Other differentials for these clinical signs include incorrect breeding date, twin pregnancy, or other noninfectious (eg, umbilical cord torsion, hydrops) and infectious (herpesvirus) causes of impending abortion.
Diagnosis
Transrectal ultrasonography is an important diagnostic tool for detection of ascending or diffuse placentitis, as it allows detailed imaging of the uterus and placenta at the cervical star where most placentitis lesions occur. Any pregnant mare with vulvar discharge should be scanned transrectally, as 90% of placentitis is ascending and can be detected at the cervical star (Fig. 6). If no abnormality is seen in that area, the mare should next be evaluated with transabdominal ultrasonography to rule out nocardioform placentitis. For transrectal imaging, a linear rectal transducer is advanced to a point immediately cranial to the cervix and entrained on the ventral arm of the uteroplacenta. The combined thickness of the uterus and placenta (CTUP) is measured at the ventral uterine body and compared with known reference ranges. In a prospective study, from 4 to 8 months of gestation, the mean CTUP in light-horse mares was 4 mm. The upper limit of reference range was 6.7 mm at 10 months, 8.54 mm at 11 months, and 11.77 mm at 12 months. Detachment of the placenta from the endometrium and echogenicity of the allantoic and amniotic fluids can also be evaluated
Fig. 6Transrectal sonogram from a mare with ascending placentitis and infection of the caudal pole of the chorioallantois. The transducer is positioned immediately cranial to the cervix, at the cervical star. Shown are the electronic calipers in use to measure the combined thickness of the uterus and placenta (CTUP). The CTUP is thickened, and separation of the chorioallantois from the uterus at the cervical star can be seen (asterisk).
Transabdominal ultrasonography is valuable for assessing fetal and placental health and for detection of nocardioform placentitis. Parameters that can be assessed include fetal presentation, fetal heart rate and rhythm, fetal activity and size, fetal stomach measurements, uteroplacental thickness, fetal fluid depth, and presence of multiple fetuses.
An equine biophysical profile score was developed for late gestation (298 days to term) based on fetal heart rate, aortic diameter, fetal activity level, uteroplacental thickness, uteroplacental contact, and maximal allantoic fluid depth. Each parameter is scored from 0 to 2 for a maximal score of 12, with a score of 8 or less being associated with a negative fetal outcome. Negative outcomes can occur regardless of the score.
Not all mares with placentitis have vulvar discharge, but in those that do, culture of the fluid is useful to determine the causative organism and its antimicrobial sensitivity pattern to guide treatment. The sample should be obtained by donning a sterile sleeve and using a guarded swab to sample the fluid from where it exits the external cervical os.
Serial progestin measurement may aid in assessing fetoplacental function in a mare with placentitis. Progestins cross-react with the progesterone antibody used in commercial progesterone assays, although the ranges for normal values can vary between laboratories. Abnormal patterns that may be observed in progestin profiles include a premature rapid decline, a marked increase occurring earlier than the expected increase around 3 weeks before parturition, or a failure to increase prepartum.
A rapid decline usually indicates fetal death or imminent expulsion, a premature increase is seen with placental pathology or fetal stress, and a failure to increase shortly before the expected time of parturition is seen with exposure to ergopeptine alkaloids produced by the endophyte fungus in fescue toxicosis.
Serum amyloid A (SAA) is an acute-phase protein secreted in response to inflammatory stimuli that is low or undetectable in healthy horses. Mares with experimentally induced placentitis had a significant increase in SAA within 96 hours after bacterial inoculation. This increase in SAA was prevented by treatment with trimethoprim sulfamethoxazole (30 mg/kg, by mouth, every 12 hours), pentoxifylline (8.5 mg/kg, by mouth, every 12 hours), and altrenogest (0.088 mg/kg, by mouth, every 24 hours) beginning at the onset of clinical signs and ending at the time of abortion or delivery.
Anecdotally, SAA has not been reliably observed to increase in clinical cases of chronic placentitis; this may be the result of the short duration of SAA in the early stages of inflammation preceding the appearance of overt clinical signs.
Management
The goals of treatment are to limit bacterial growth and expansion, maintain myometrial quiescence, and reduce the inflammation associated with bacterial infection of the fetal membranes. Thus the primary treatments for placentitis consist of antimicrobials, anti-inflammatory drugs, and altrenogest. Duration of each of these treatments varies by clinician and response to treatment. Periodic reevaluation of the fetus is necessary to ensure that the fetus is still alive.
Several studies have evaluated the penetration of antimicrobials into fetal fluids. Both systemically administered penicillin (penicillin G potassium, 22,000 IU/kg, slowly IV, every 6 hours) and gentamicin (6.6 mg/kg, IV, every 24 hours) reach the allantoic fluid at concentrations similar to and 20% less than systemic concentrations, respectively.
Murchie TA, Macpherson ML, LeBlanc MM, et al. A microdialysis model to detect drugs in the allantoic fluid of pregnant pony mares. In Proceedings. San Antonio, TX: 49th Ann Conv Am Assoc Equine Pract 2006;49:118–21.
Systemically administered trimethoprim sulfamethoxazole (30 mg/kg, by mouth, every 12 hours) and pentoxifylline (8.5 mg/kg, by mouth, every 12 hours) also reached the allantoic fluid at concentrations similar to serum.
Enrofloxacin (5 mg/kg, IV, every 24 hours) reached therapeutic concentrations in fetal fluids in 7 normal mares at 260 days gestation treated for 11 days, with no detected fetal lesions. The investigators cautioned that further research is needed to determine if enrofloxacin is toxic at other stages of pregnancy, after a longer duration of treatment, or once foals are delivered and weight-bearing.
Doxycycline (10 mg/kg, by mouth, every 12 hours) was found to diffuse through the fetoplacental unit of late pregnant mares with the highest concentration in the allantoic fluid of 73 ng/mL.
D’el Rey Dantas FT, Canisso IF, et al. Doxycycline diffuses through the fetoplacental unit of late pregnant mares and accumulates in the joints of resulting foals. In Proceedings. Denver, CO: 65th Ann Conv Am Assoc Equine Pract 2019;65:61–2.
The minimum inhibitory concentration to inhibit growth of 90% of organisms (MIC90) for intragastric administration of a similar dose of doxycycline was determined to be ≤1.0 μg/mL for S zooepidemicus.
Ceftiofur sodium (4.4 mg/kg, intramuscularly [IM], every 24 hours) and ceftiofur crystalline free acid (6.6 mg/kg, IM, every 96 hours) were found to incompletely transfer across fetal membranes in pony mares.
Disposition of desfuroylceftiofur acetamide in serum, placental tissue, fetal fluids, and fetal tissues after administration of ceftiofur crystalline free acid (CCFA) to pony mares with placentitis.
Duration of treatment influenced recovery of bacteria from the postpartum uterus in mares with induced placentitis. Mares with negative postpartum uterine culture results were treated for at least 3 weeks. This fact also suggests the need for postpartum uterine treatment in mares with placentitis.
In a combination treatment experiment in mares inoculated with S zooepidemicus to induce ascending placentitis, mares treated with trimethoprim sulfamethoxazole (30 mg/kg, by mouth, every 12 hours), pentoxifylline (8.5 mg/kg, by mouth, every 12 hours), and altrenogest (0.88 mg/kg, by mouth, every 24 hours) carried pregnancies longer and delivered more live foals than untreated, inoculated mares. Treatment was initiated when clinical signs of placentitis were observed, such as ultrasonographic evidence of increased CTUP, placental separation, or a change in fetal fluid character, or the onset of mammary development or vulvar discharge.
A study evaluated the use of antibiotics alone or in combination of immunomodulators to prevent preterm birth or increase neonatal viability in induced placentitis. Mares with induced placentitis were treated with trimethoprim sulfamethoxazole alone (30 mg/kg, by mouth every 12 hours), trimethoprim sulfamethoxazole and tapering dexamethasone doses (40 mg IV every 24 hours for 2 days, followed by 35 mg IV every 24 hours for 2 days, followed by 25 mg IV every 24 hours for 2 days), or trimethoprim sulfamethoxazole and aspirin (50 mg/kg, by mouth, every 12 hours). Pregnancy outcomes were similar between groups suggesting that strategic treatment with antimicrobials can substantially improve pregnancy outcome.
In a study assessing the value of firocoxib (0.3 mg/kg, by mouth, one time loading dose; 0.1 mg/kg, by mouth, every 24 hours) in induced placentitis, some cytokine concentrations were significantly lower in allantoic fluid in treated mares. Prostaglandin concentrations were variable between groups. Results suggested a trend toward suppressive effects of firocoxib treatment on cytokine and prostaglandin concentrations in fetal fluids of mares with induced placentitis.
Progestin treatment has been described for use in women for preterm labor and mares to promote uterine quiescence and is often prescribed for placentitis in mares.
However, it may be warranted to discontinue progestin therapy before parturition depending on the case. One study of the effect of altrenogest administration on parturition and neonatal viability in normal mares revealed a prolonged second stage of parturition, lower neonatal respiratory rate, and higher plasma pH during the first 30 minutes of life. Altrenogest did not inhibit parturition.
The addition of long-acting altrenogest (0.088 mg/kg, IM, every 7 days) and estradiol cypionate (10 mg/mare, IM, every 3 days) to trimethoprim sulfamethoxazole (30 mg/kg, IV, every 12 hours) and flunixin meglumine (1.1 mg/kg, IV, every 24 hours) for treatment of induced placentitis has been evaluated. Foal survival at parturition and 7 days after delivery was similar between treatments; however, the few foals deemed high risk after parturition originated in groups treated with both trimethoprim sulfamethoxazole and flunixin meglumine or a combination of sulfamethoxazole, flunixin meglumine, and estradiol cypionate.
Hydrops allantois and hydrops amnion are considered reproductive emergencies in the mare because of their association with prepubic tendon rupture, uterine rupture, and abdominal wall herniation.
Slovis NM, Lu KG, Wolfsdorf KE, et al. How to manage hydrops allantois/hydrops amnion in a mare. In Proceedings. Nashville, TN: 59th Ann Conv Am Assoc Equine Pract 2013;59:34–9.
of gestation when the condition arises. Hydrops allantois is more common than hydrops amnion, and the clinical patterns of the 2 conditions differ somewhat in that with hydrops amnion, the fluid volume is not as marked as with hydrops allantois
and the abdominal distension develops more gradually over a period of weeks to several months during the last half of gestation, whereas with hydrops allantois, fluid volume and abdominal distension are marked and arise more acutely, over 1 to 2 weeks, also during the last part of gestation. Suspicion of a hydropsic condition is made by visual observation of abdominal distension greater than what would be expected for the stage of gestation (Fig. 7) or by usually rapidly developing, gross abdominal distension (Fig. 8) accompanied by signs of increasing discomfort and distress. Differential diagnoses include twin pregnancy, colic, ascites, abdominal wall herniation, prepubic tendon rupture, hypoproteinemia, and other causes of ventral edema.
Fig. 7Mare in month 6 of gestation, in early stage of hydrops allantois.
In a report of 5 cases of hydrops allantois, placentitis was observed to an extent in all cases, but it was not determined whether the hydropsic condition caused the placentitis, or vice versa.
L interrogans serogroup Pomona has been associated with hydrops allantois, which may warrant testing of affected mares and fetal tissues, and maintaining a mindfulness of the zoonotic potential during treatment.
Physical examination: Diagnosis of a hydropsic condition usually starts with visual recognition of marked abdominal distension. With increasing abdominal enlargement, mares become reluctant to move, move stiffly, and may spend more time lying down. Heart rate and respiratory rate are usually high, as mares adopt a low-tidal-volume high-rate breathing pattern in response to the high abdominal pressure behind the diaphragm. The breathing quality may be labored as the hydraulic pressure in the abdomen progressively impairs diaphragmatic contraction. The skin along the caudal aspect of the ventral abdomen becomes palpably taut and may be highly sensitive to palpation. Edema often accumulates in a large ventral plaque along the abdomen. The excessive distension and weight can challenge body wall integrity, and the lateral and ventral abdominal walls should be carefully evaluated daily for regions of fascial separation and bulging of muscle into the subcutaneous layer of the skin, particularly in the mammary region, where the prepubic tendon attaches to the pelvic brim. When the excessive weight stretches and compromises the prepubic tendon, blood-tinged mammary secretions may be seen. Measuring abdominal circumference, distance from mammary gland to umbilicus, and distance from the umbilical scar to the ground can be objective ways of monitoring progression as abdominal contours grow.
Ultrasound imaging: Upon transrectal palpation and ultrasonography, the uterus is grossly distended, taut, and often domes dorsally above the pelvic inlet to protrude into the pelvic canal. The contained fluid volume may be such that the fetus cannot be palpated or seen on ultrasonography (Fig. 9). The caudal area of the uterus and the cervix should be evaluated for placentitis, although the CTUP is often within normal limits with hydrops allantois.
Fig. 9Transabdominal sonogram of the uterus from a mare with hydrops allantois. Notice the fetus is not in view because of the extreme volumes of fetal fluids.
Transabdominal ultrasonography can be performed to evaluate the depth of the amnionic and allantoic fluid compartments, character of the fluid, health of the placenta and fetus, and integrity of the abdominal wall; to gain a general assessment of the viewable abdominal contents; and to rule out some of the differential diagnoses. In a 1995 study
of 33 healthy mares that were scanned transabdominally within 2 months of parturition, the maximum vertical depth of amnionic fluid was 7.9 ± 3.5 cm and the maximum vertical depth of allantoic fluid was 13.4 ± 4.4 cm. In another study of fetoplacental well-being in normal pregnancies, total fetal fluid depth was not significantly related to the gestational age in mares at 6 to 12 months' gestation, but the distribution of fetal fluid was related to the position of the fetus within the uterus.
Slovis NM, Lu KG, Wolfsdorf KE, et al. How to manage hydrops allantois/hydrops amnion in a mare. In Proceedings. Nashville, TN: 59th Ann Conv Am Assoc Equine Pract 2013;59:34–9.
Although it is not necessary for diagnosis, blood work, including serum chemistry, is recommended in the evaluation. Hypocalcemic mares may be more vulnerable to hypotensive shock on removal of the fetal fluids, and low blood calcium warrants intravenous calcium supplementation as preparations are made for reduction of the hydrops.
Slovis NM, Lu KG, Wolfsdorf KE, et al. How to manage hydrops allantois/hydrops amnion in a mare. In Proceedings. Nashville, TN: 59th Ann Conv Am Assoc Equine Pract 2013;59:34–9.
Hydrops is frequently followed by retained fetal membranes, and parenteral calcium may also help with the uterine atony after removal of the fetus. Findings of high creatine kinase, alkaline phosphatase, and serum amyloid A should point the veterinarian’s attention to possible body wall compromise as a sequelae to the hydrops.
Slovis NM, Lu KG, Wolfsdorf KE, et al. How to manage hydrops allantois/hydrops amnion in a mare. In Proceedings. Nashville, TN: 59th Ann Conv Am Assoc Equine Pract 2013;59:34–9.
Intervention and treatment require a conversation with the client regarding the well-being and prognosis for both the mare and the fetus. Although there is one published report of a live foal birth following conservative management of a mare with hydrops amnion,
the more common hydrops allantois seems to confer a uniformly grave prognosis on foal survival. In nearly all instances of uterine hydrops of either type, the goal of intervention is to end the pregnancy to preserve the life of the mare.
The timing of and the method used to terminate the pregnancy have implications for the mare’s well-being; it depends on factors such as the volume of fluid, compromise of the mare’s body wall, the mare’s gestational age, the mare’s overall health, and the potential of a viable fetus.
If hydrops is diagnosed at an earlier stage of gestation or before the volume of the uterine fluid has become marked, elective termination of the pregnancy via routine protocols may be undertaken. Once the uterus has become grossly distended with a large volume of fluid, however, reduction of the hydrops should involve controlled removal of the allantoic fluid, over a period of one to several hours, before the fetus is removed. Rapid removal, even over a period of several hours, can induce hypovolemic shock and collapse or death, as the abrupt reduction in pressure in the abdominal cavity causes venous pooling in the splanchnic circulation with loss of effective circulating blood volume, blood pressure, and cardiac output. For these reasons, the mare should be prepared for the procedure. A large-bore intravenous catheter (10- to 14-gauge catheter) is placed in the jugular vein and an initial bolus of 10 L of a polyionic crystalloid fluid is administered. This step is followed by the continuous administration of fluids as the fluid is removed from the uterus, with the final administered volume of fluid measuring about one-fourth the volume of drained fetal fluid. The mare’s heart rate, respiratory rate, and overall affect should be continuously monitored by a person assigned to that role, and if the mare becomes tachycardic (heart rate >56–60 beats/min), ataxic, or shaky, drainage of the fluid is paused and a colloid fluid or hypertonic saline is administered to correct hypotension.
Slovis NM, Lu KG, Wolfsdorf KE, et al. How to manage hydrops allantois/hydrops amnion in a mare. In Proceedings. Nashville, TN: 59th Ann Conv Am Assoc Equine Pract 2013;59:34–9.
In preparation for intravaginal manipulation, the tail is wrapped, the perineum is cleansed, and the Caslick suture is removed if present. A cream containing hyoscine butylbromide, misoprostol, or prostaglandin E2 can be applied to the cervix to induce cervical softening and facilitate intrauterine manipulations. The operator should prepare as for an aseptic procedure. Reaching through the softened cervix, the chorioallantois is identified. The chorioallantois at the internal os can be very thick, and an instrument such as a blunt scissor or an Argyle-type chest drain and trocar may be needed to penetrate it.
Slovis NM, Lu KG, Wolfsdorf KE, et al. How to manage hydrops allantois/hydrops amnion in a mare. In Proceedings. Nashville, TN: 59th Ann Conv Am Assoc Equine Pract 2013;59:34–9.
Use of a chest drain to pierce the chorioallantois enables attachment of sterile tubing to the drain once the trocar has been withdrawn, allowing better control of the rate of fluid drainage over 1 to 2 hours (Fig. 10). Because of the marked uterine distension and resulting myometrial flaccidity, fluid expulsion following rupture of the fetal membranes may not be explosive. After most of the fetal fluid has been removed, oxytocin can be administered to promote uterine contractility, delivery of the fetus, and expulsion of the placental membranes.
Manual extraction of the fetus is often necessary because of the vastly increased uterine size, inertia, and weakened abdominal musculature. Dystocia is common, and retention of the fetal membranes should be expected. The fetus is usually euthanized on delivery. The mare should continue to be monitored for hemodynamic stability multiple times daily for the next 1 to 2 days, with recording of the heart rate, respiratory rate, temperature, peripheral pulse quality, cutaneous temperature of the extremities, skin turgor, capillary refill time, and urine output.
Fig. 10Elective reduction of hydrops allantois. Operator has pierced chorioallantois transcervically with a 24F chest-tube trocar and is allowing controlled flow of allantoic fluid out of the uterus through Bivona tubing. The mare is being supported with IV fluids.
Because of the prolonged cervical and uterine manipulations and frequent retained fetal membranes, broad-spectrum antimicrobials should be prescribed and routine postpartum care and monitoring provided. Application of abdominal support bandages or girdles likely gives the mare a degree of comfort and can continue to be provided as needed while the mare convalesces.
Subsequent Fertility
In a report of 5 mares, 1 of 2 mares with reported fertility data conceived during the same season in which an elective hydroallantois abortion was performed; the other mare in that report remained barren after several cycles of natural breeding.
Summary: Use clinical signs and ultrasonography to diagnose and monitor abdominal enlargement. If the hydropsic fluid accumulation is severe enough to cause pain, respiratory impairment, or challenge to the prepubic tendon attachments, consider elective removal of the fluid and induction of parturition to save the mare.
Prepubic Tendon Rupture and Abdominal Wall Hernia
Incidence
The prepubic tendon is composed of the tendons and aponeuroses of the muscles that make up the ventral and lateral body walls, including the rectus abdominis and abdominal oblique muscles. The prepubic tendon serves as the pelvic attachment of the linea alba.
Abdominal wall hernias and prepubic tendon rupture are emergencies because of the risk of evisceration. Prepubic tendon rupture is reported in draft mares and light breeds, typically in the last 2 months of pregnancy.
In one review of 13 cases of body wall defects, only 3 cases were associated with hydrops allantois or hydrops amnion, and no predisposing conditions were reported for 10 cases.
In that report, the median age at presentation was 13 years, all were light-breed mares, and all mares had produced at least one foal previously. The median time in gestation when naturally occurring body wall defects were diagnosed was 324 days.
Clinical signs
Clinical signs at initial evaluation of mares with body wall defects (either abdominal wall hernia or prepubic tendon rupture) included pitting ventral edema, pain on palpation of the abdominal wall, easily depressible abdominal wall tissue, colic, tachycardia, ventral displacement of the abdominal wall (Fig. 11), hemorrhagic mammary secretions, flattened mammary glands, reluctance to walk, abdominal enlargement, and sudden onset of lordosis.
Fig. 11Mare with ventrally displaced body wall secondary to failure of the prepubic tendon attachments at the pubic bone. This severity of structural failure predisposes the mare to body wall herniation and progression to rupture and evisceration.
Rupture of the prepubic tendon should be distinguished from displacement or herniation of other abdominal musculature because prepubic tendon rupture implies loss of all ventral and lateral abdominal support.
Clinical suspicion of abdominal wall defects can be confirmed with transabdominal ultrasonography. Ventral and ventrolateral abdominal wall muscles in pregnant and nonpregnant mares with and without abdominal wall disease were evaluated with transabdominal ultrasonography to establish normal ranges.
There were no significant differences between light and heavy mares and no effect of pregnancy status or age on measurements of muscle thickness. Two pregnant mares with abdominal wall disease were evaluated, and muscle measurements were similar to those of normal mares. However, echotexture changes with increased intramuscular edema and increased echogenicity consistent with hemorrhage were present.
Slovis NM, Lu KG, Wolfsdorf KE, et al. How to manage hydrops allantois/hydrops amnion in a mare. In Proceedings. Nashville, TN: 59th Ann Conv Am Assoc Equine Pract 2013;59:34–9.
Conservative management includes stall rest and abdominal support. Frequent or continuous fetal and mare monitoring, pain management, repeated ultrasonography, and treatment of placentitis if necessary were associated with a better outcome than interventional management for mares with body wall tears. One review (n = 13 with 10 mares surviving to discharge) found no difference in mare survival between mares with body wall hernia only and mares with prepubic tendon tear plus body wall hernia.
Serial monitoring of mammary gland secretions can aid in predicting foaling or in timing induced parturition, although this can be complicated by placentitis. Changes to monitor include an increase in calcium to concentration > 40 ng/dL and inversion of the sodium and potassium concentrations. Elective cesarean delivery in mares with prepubic tendon rupture or significant body wall tears is typically terminal.
Summary: Some of the most noticeable signs in mares with a failing prepubic tendon are abdominal discomfort, colic, ventral edema, easily compressed areas of the body wall, flattened taut mammary glands, tachycardia, blood-tinged mammary secretions, reluctance to move, and a lordotic posture. Provision of abdominal support, an adequate analgesic protocol, stall confinement, and daily monitoring seem to yield better outcomes for the foal without compromising mare survival than does intervention by induced parturition or cesarean section surgery.
Uterine torsion
Torsion of the uterus is an uncommon problem in mares, but it is a significant risk to survival of both the fetus and the dam. Both nonsurgical and surgical methods of correcting the torsion have been described and will be discussed. Torsion of the uterus can affect mares of any age and parity and most frequently arises as an acute condition in the last 60 days of gestation, but it can also occur at the earlier and later stages of gestation.
Predisposing factors that set up the gravid uterus to rotate may include the mare falling, mare rolling, presence of a large fetus with a relatively small volume of fetal fluids, and vigorous fetal movement,
but in most instances no precipitating events or factors can be confirmed. Multiple studies have reported that the chance of survival in both mare and fetus is higher when torsion occurs earlier, rather than later, in gestation. A cutoff point of 320 days of gestation has been reported, with significantly higher survival percentages for cases occurring before that time, compared with mares in which uterine torsion happens greater than 320 days.
Uterine torsion manifests in signs of depression and colic, which tends to be mild to moderate in severity and intermittent to persistent. The degree of colic has been likened to that seen with intestinal impaction,
but it is likely to be more severe if gastrointestinal segments are incorporated into the torsion. Routine colic treatment may yield transient improvement, but the signs of abdominal discomfort are usually not completely resolved, or they return. As the colic is often mild, and possibly intermittent, a period of several days may pass between the onset of abdominal discomfort and diagnosis of uterine torsion. Involvement of gastrointestinal tract structures in the uterine torsion elicit signs of abdominal pain commensurate with the type of gastrointestinal disease. In one retrospective study of 19 mares,
approximately 50% of the cases had concurrent gastrointestinal disease, including inflammatory bowel disease, impaction, large colon volvulus, right dorsal displacement of the large colon, and gastric rupture. In a 1995 case report
mares with uterine torsion also had herniation of the jejunum through a broad ligament and incorporation of the small colon in the torsion. For these reasons, colic in the pregnant mare should prompt detailed examination of both the gastrointestinal and reproductive tracts. The pregnant uterus and broad ligaments should be palpated transrectally as part of the evaluation for colic.
Torsion is diagnosed by rectal palpation. The direction of the torsion, and the degree of rotation, vary. Although both directions have been reported as most frequent in different retrospective case series, rotation of the uterus in the clockwise direction is generally thought to be more frequent than counterclockwise rotation.
Factors affecting the prognosis for uterine torsion: the effect of treatment based on measurements of serum progesterone and estradiol concentrations after surgery.
With a clockwise rotation (with the mare being viewed from the rear), the left broad ligament can be palpated as a taut strap or band pulled horizontally and dorsally over the uterus, or less reliably, the right broad ligament being pulled more vertically and ventrally under the uterus. With counterclockwise rotation, the right broad ligament can be palpated being pulled dorsally toward the top of the uterus, and the left ligament will be pulled ventrally. The magnitude of torsion can vary from less than 180° to 540°, with most torsions diagnosed as less than or equal to 180°.
A torsion of 360° or more creates the most tension on the vascular structures in the broad ligaments and has greater potential to impair placental perfusion and fetal oxygen delivery. It has been posited by some investigators that torsions less than 180° may be within normal variation of uterine movement and may resolve spontaneously.
Once uterine torsion is diagnosed, a vaginal speculum examination adds additional information in indicating whether the cervix is open or closed, which can influence the choice of intervention.
If it is planned to attempt correction of the torsion on site and nonsurgically, it is necessary to correctly identify the direction of the rotation. If this cannot be done with certainty, nonsurgical correction should not be undertaken, as the corrective measures can exacerbate the torsion and cause uterine wall injury. The 2 nonsurgical methods of reducing uterine torsion are to manually rotate the uterus by manipulating the fetus per vaginum in the standing mare, or to roll the mare’s body around the uterus while under general anesthesia.
In the few cases in which the mare is at term and the cervix is open, derotation may be possible by reaching a well-lubricated arm through the cervix, rupturing the chorioallantois and allowing the fetal fluids to drain, and grasping the foal on its ventrolateral aspects, optimally the forelimbs and some part of the body. Small arcs of rotation are begun, in the direction opposing the torsion. Wider and wider excursions are created, until the fetus and surrounding uterus have partially or fully derotated. It may require several cycles of the procedure before the uterus is restored to the normal position. This technique should be attempted only in torsions less than or equal to 270°.
Once the uterus is derotated, the foal should be delivered vaginally. If a term mare with torsion has a closed cervix, or uterine wall compromise is suspected, this technique cannot be used and the mare should be referred for ventral midline celiotomy.
The second nonsurgical correction method involves rolling the mare, and has been well described.
This maneuver exploits the mass and inertia of the pregnant uterus and aims to rotate the dam’s body 360° over the stationary uterus. The technique is to roll the mare, while anesthetized, in the same direction of the torsion while a plank is placed on the abdomen directly over the uterus, and weighted. By rotating the mare in the same direction in which the uterus is rotated while holding the latter in place, the mare’s body catches up with the uterus. Accurate determination of the direction of torsion is necessary before starting his procedure. For a clockwise torsion (uterus rotated toward the right when viewed from behind), the mare is anesthetized with routine intravenous anesthesia and positioned in right lateral recumbency. A long wooden plank is placed on the paralumbar fossa, running perpendicularly to the mare’s long axis.
An assistant sits or stands on the plank, weighting and holding the uterus in place while ropes are used to pull the mare into dorsal recumbency, over into left lateral recumbency, into sternal recumbency, and back to right lateral recumbency. Rectal palpation with the mare pulled into sternal recumbency will indicate whether the uterus has returned to the normal position. For a counterclockwise rotation, the mare is positioned in left lateral recumbency and maneuvered through a 360° roll using the same technique. If torsion persists after rolling, the procedure can be repeated, but failure to correct the torsion with 2 attempts should prompt consideration of surgical methods of resolution.
The rolling technique necessitates general anesthesia of the mare, but has the advantages of being feasible to attempt at most farms, being associated with a reasonable to good chance of success, and being inexpensive, compared with the costs of hospitalization and surgery. The rolling technique is most appropriate for light-breed mares in months 7 through 10 of gestation in which the owners prefer not to pursue surgery and in which no concurrent gastrointestinal tract disease is suspected.
The technique is not without the potential for complications, including all the possible complications attending general anesthesia and recovery, plus uterine rupture, premature placental separation, and abortion.
Mares that are close to term are more likely to experience significant complications with the procedure and are better candidates for surgical resolution. Mares in which gastrointestinal disease is suspected should also be managed surgically to permit both reduction of the uterine torsion and evaluation of the gastrointestinal tract.
Surgical options for resolving uterine torsion include standing flank laparotomy, recumbent flank laparotomy, and ventral midline celiotomy. Standing flank laparotomy in mares that are less than 320 days gestation and that have no concurrent gastrointestinal involvement appears to yield the best outcome for mares and foals,
although recumbent flank laparotomy and ventral midline celiotomy can also resolve the torsion and result in delivery of a live foal. Uterine torsion in mares later than 320 days in gestation is likely to be met with more complications, irrespective of the method of resolution. After 320 days, the method of correction has less effect on outcome, and the risk of complications is higher. Foals delivered at the time of torsion correction should be managed as high-risk neonates for neonatal asphyxia syndrome or sepsis. Mares in which the fetus is alive at the time of correction have a good prognosis for delivering a live foal.
Factors affecting the prognosis for uterine torsion: the effect of treatment based on measurements of serum progesterone and estradiol concentrations after surgery.
Future fertility in the mare is likewise favorable: stage of gestation, correction method, direction or degree of torsion, and postoperative wound complications had no influence on subsequent fertility.
Surgical correction of uterine torsion is best done at a surgical facility. If the surgical expertise and technical assistance are available, standing flank laparotomy is possible at a farm with a dedicated area for veterinary work that is clean, has horizontal work surfaces, and includes stocks. The reader is referred to recent excellent descriptions for details of the surgical procedure.
In brief, the mare is restrained in stocks and started on standing intravenous sedation; a constant-rate infusion (CRI) of detomidine is useful for this purpose. A caudal epidural may also be placed but is typically not necessary. The lateral body wall on the side toward which the uterus is rotated is clipped and prepped for aseptic surgery. Local anesthesia is placed in a line block at the incision site, which will lie halfway between the last rib and the tuber coxa and follow a vertical line starting just above the dorsal margin of the internal oblique muscle and extending distad approximately 20 cm. The local anesthetic solution is infiltrated in the muscle and subcutaneous layers. Entry to the peritoneal cavity is made by a modified grid approach, in which, once the skin incision is made, the external abdominal oblique is incised vertically while a window is created through the internal oblique and transverse muscles by blunt separation of their fibers parallel to their orientation. The peritoneum is bluntly penetrated. The surgeon’s hand is advanced into the abdominal cavity and placed underneath the gravid horn. With the surgeon lifting and pushing on the uterus rather than pulling on it, the uterus is rocked back and forth, until the uterus and fetus have flipped back to their normal position. Correction can be confirmed directly by palpation of the broad ligaments and by rectal palpation. Closure of the body wall is routine; the peritoneum is not typically closed, and the muscle layers opened during the approach are reapposed with #1 or #2 absorbable suture placed in a simple continuous pattern. The subcutaneous layer may be closed with the muscle layer or can be sutured in a separate layer, also in absorbable suture, whereas the skin is closed in nonabsorbable suture.
Ventral midline celiotomy is the approach of choice if the uterus is ruptured, uterine wall compromise is suspected (eg, if the torsion is of several days’ duration and congestion and edema of the uterus is likely, making it friable), degree of rotation is greater than or equal to 360°, the fetus is deceased and the mare is preterm, the mare has gastrointestinal tract, the mare is intractably painful, or if attempts at standing correction are unsuccessful.
Postoperative care of mares should include analgesics, antimicrobials, and meticulous incisional care. Mares that undergo surgery, especially ventral midline celiotomy, close to term should be considered a high-risk pregnancy, as the abdominal press recruited during active labor will challenge the sutures and/or staples used in the surgical closure and can result in catastrophic body wall failure and evisceration. Outfitting such a mare with an abdominal support wrap (nonstretching adhesive wrap or a commercially available abdominal girdle) before parturition starts is recommended. In one study of 7 mares with uterine torsion that underwent midline celiotomy, postoperative monitoring including assaying for progesterone (P4) and estradiol (E2), and mares with hormone profiles suggestive of inflammation or compromise were managed medically with a combination of a tocolytic, synthetic progesterone, and antimicrobial.
Factors affecting the prognosis for uterine torsion: the effect of treatment based on measurements of serum progesterone and estradiol concentrations after surgery.
Fetal monitoring is also a part of postsurgical care in the pregnant mare.
Summary: Uterine torsion most frequently, but not exclusively, arises in mares in the last trimester of gestation and initially manifests as colic. The uterine torsion may incorporate gastrointestinal structures, in which case the colic will likely be more severe. The torsion should be corrected promptly for the best chance at mare and foal survival. Correction can be undertaken with nonsurgical means or with surgery. The prognosis for future fertility is good.
Clinics care points
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Injuries involving reproductive tract tissues are similar to those involving other body areas in that prompt recognition, thorough evaluation, and intervention underlie a favorable outcome
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In traumatic injuries, initial treatment to mitigate the peak severity and duration of inflammation and edema are particularly important in the external genitals of male horses
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Whether a practitioner will undertake full management of a reproductive tract emergency in the field or elects to evaluate and stabilize the patient and then refer, the first-line interventions provided can play the dominant role in outcome for the stallion, fetus, or mare
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Clear communications and management of client expectations are key skills for veterinarians managing reproductive emergencies
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Murchie TA, Macpherson ML, LeBlanc MM, et al. A microdialysis model to detect drugs in the allantoic fluid of pregnant pony mares. In Proceedings. San Antonio, TX: 49th Ann Conv Am Assoc Equine Pract 2006;49:118–21.
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Disposition of desfuroylceftiofur acetamide in serum, placental tissue, fetal fluids, and fetal tissues after administration of ceftiofur crystalline free acid (CCFA) to pony mares with placentitis.
Slovis NM, Lu KG, Wolfsdorf KE, et al. How to manage hydrops allantois/hydrops amnion in a mare. In Proceedings. Nashville, TN: 59th Ann Conv Am Assoc Equine Pract 2013;59:34–9.
Factors affecting the prognosis for uterine torsion: the effect of treatment based on measurements of serum progesterone and estradiol concentrations after surgery.
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