CHAPTER 76 Periparturient Infections and Structural Abnormalities
A variety of periparturient conditions may interfere with normal parturition or adversely affect the health or fertility of does after parturition. Fortunately, these conditions are not encountered frequently in goats but they are of grave concern to owners when they do occur.
Excessive accumulation of fluid in the amniotic (hydramnios) or the allantoic (hydrallantois) sacs are infrequent complications of pregnancy. They are common in cattle but are rare in other species,1 although there are two published reports of hydrops in goats.2,3 The underlying cause of this condition is not known, but hydrops is encountered in the latter half of pregnancy and is characterized by rapid and progressive abdominal distention. The distention is a reflection of the accumulation of excess fluid within one or the other of the placental compartments. Normal fluid amounts in the pregnant goat uterus are 0.5 to 1.5 L, which may be increased greater than 10-fold in cases of hydrops. Other clinical signs are the result of compression of other organs by the expanding uterus and include a decrease in appetite, tachycardia, tachypnea, dyspnea, generalized weakness, and, finally, recumbency.
The excess fluid that accumulates in hydrops has an electrolyte composition more similar to extracellular fluid than to amniotic or allantoic fluids. In cows, an abnormal fetus (hydramnios) or placenta (hydrallantois) is associated with excessive accumulation of fluids. In goats, the fetus may have congenital abnormalities, be underdeveloped, or be apparently normal but not viable. The placenta has gross and microscopic pathologic changes, most commonly edema and necrosis. The placentomes are reduced in number and are structurally abnormal.
Diagnosis is based on presenting signs and the results of a physical examination. Differential diagnosis includes intestinal obstruction, ascites, ruminal tympany, hydrometra, and normal multiple fetuses.2 Palpation and ballottement of the abdomen reveal the fluid accumulation, whereas ultrasonography shows that the accumulation of fluid is within a thin-walled uterus. Rectal palpation, as used for cattle, is impractical for diagnosis in goats. Ultrasonography can be used to demonstrate abnormal placentation in hydrallantois, abnormal placentomes, and a decrease in placentome numbers.
Treatment is directed at evacuation of the uterus by cesarean section or induced termination of pregnancy with prostaglandin. Uterine distention predisposes to uterine inertia, and assistance is necessary to remove the fetuses from the uterus. Cesarean section may be contraindicated in these cases as it risks uterine rupture, cardiovascular problems, and potentially fatal hypotension, all from the rapid loss of uterine fluids. Intravenous fluid therapy may be a useful adjunct therapy. Retained placenta and metritis are possible sequelae, requiring therapy after delivery.
Vaginal prolapse is fairly common, although not as common as in cattle or sheep. One author claims that it is seen most often in Saanens.4 The predisposing causes are thought to be similar to those in cattle or sheep and include heredity, increased intra-abdominal pressure from advanced pregnancy, excess estrogen in the forage, previous dystocia, and relaxed perineal tissues due to confinement. If left uncorrected, vaginal prolapse will progress in severity and ultimately result in dystocia.
Early or mild cases are seen only when the doe is recumbent. A small, egg-sized portion of the vaginal floor protrudes through the vulvar lips and disappears into its normal position when the doe rises. Treatment often is not necessary in these cases, although the owner should watch these does to determine whether the condition progresses. Oily antibiotic preparations can be applied to keep the tissues moist and the doe can be confined at night with her hindquarters elevated. Adequate exercise can also be beneficial.
Complete vaginal prolapse does not correct itself spontaneously. The floor and walls of the vagina protrude from the vulvar lips and often result in tenesmus, which further aggravates the condition. The exposed tissue is prone to trauma and may become lacerated and infected. Enlargement due to edema occurs because of disruption of the vasculature of the vagina when prolapsed. In some cases, the urinary bladder is trapped within the prolapse and cannot be emptied, and thereby causes further enlargement of the prolapse. A vaginal-cervical prolapse occurs when the cervix becomes exteriorized along with the vagina. The cervical seal may be dislodged with vaginal-cervical prolapse, exposing the uterus to possible infection.
Treatment of vaginal prolapse entails cleaning the exposed tissue, decreasing its size, and replacing it into normal position. Epidural anesthesia assists replacement of the prolapse and helps to relieve tenesmus after replacement. The vagina is cleaned with mild soap and lubricated with an emollient. Elevation of the exposed tissue assists in evacuation of the bladder. Application of diffuse pressure to the organ, such as with a towel, and elevation of the hindquarters can reduce some of the edema. The vagina is replaced, making sure that fingertip pressure, a potential cause of lacerations, is not used.
After replacement, the vagina is retained in some manner. A paddle-shaped ewe prolapse retainer can be inserted to hold the vagina in place. This instrument does not interfere with parturition but may be difficult to hold in place in goats. Various suture patterns have been used to restrict the vulvar opening, thus preventing a subsequent prolapse. These need to be monitored carefully and opened prior to kidding, or dystocia will result. A shoelace pattern has been advocated because it has the advantage of being easily opened by the owner during parturition but can be left in place to secure the vagina after delivery. A modified Buhner suture secured by a bow knot accomplishes the same goal. Nonsteroidal analgesics, such as flunixin meglumine (1.1 mg/kg IM, daily), may suppress straining after replacement of the prolapse.
Prevention of vaginal prolapse is based on culling previously affected individuals. Once a doe suffers a vaginal prolapse, the prolapse will be repeated during each subsequent pregnancy. Some owners may not want to cull these goats, so they should be advised to watch affected does carefully during late pregnancy. Sexual rest for several years may allow the vaginal tissues to heal. Adequate exercise and prevention of obesity are also important to reduce recurrence.