CHAPTER 16 Immediate Care of the Postpartum Mare and Foal

EXAMINATION OF THE NORMAL POSTPARTUM MARE

The initial examination of the postpartum mare should be simple, as intervention beyond absolute necessity may disrupt the adaptation processes that are under way during this time. The examination should consist of evaluation of the mare’s behavior including attitude and interaction with her foal and her general condition including character of pulse and respiration, color of mucous membranes, degree of alertness, and responsive reaction to stimuli. The udder also needs to be carefully examined for consistency of mammary secretions and patency of the teats. Further evaluation of the systemic condition, such as rectal and vaginal examination, blood counts, and clinical chemistry tests, are not indicated unless a specific problem is suspected based on the general examination.

The placenta should be thoroughly examined and weighed once it is passed. A normal equine placenta weighs approximately 14% of the mare’s body weight or between 10 and 18 lb. A placenta weighing greater than 18 lb is edematous and indicates that the foal may not have received adequate gas exchange in utero. Foals from excessively heavy placentas need to be considered at high risk for neonatal problems. The chorioallantoic and allantoamnionic surfaces and the umbilical cord need to be examined. Irregularities in color, thickness, length of villi, and the presence of any secretions should be noted. If placental abnormalities are found or the foal is born before 325 days of gestation, a blood sample from the foal should be obtained and a complete blood count performed. Foals that experience in utero stress may have either a low white blood cell count (<5000 cells/μl) and low fibrinogen level (<200 mg/dl) if the stress was of short duration leading to premature delivery, or if the stress was prolonged, a high white blood cell count (>8000 cells/μl) and a high fibrinogen level (>400 mg/dl).¹ Premature foals or foals that experience in utero stress have a greater chance of survival with appropriate nursing care.

CARE OF THE NORMAL POSTPARTUM MARE

Mares should foal in a clean, dry, draft-free area that has protection from excessive sun and wind. If the climate permits, a small, clean grass paddock is best; otherwise, a well-bedded dry stall that is at least 12 ft by 12 ft will do. Mares housed in paddocks can be grouped with either one or two mares or be left by themselves. The number of mares in the paddock should be minimal to decrease competition among the mares for food and space and to allow the mare to bond with her foal.

During the postpartum period mares need exercise to promote uterine involution and to stimulate appetite and gastrointestinal function. Leaving a mare in a stall for prolonged periods is detrimental, as the mare may accumulate intrauterine fluid leading to metritis or septicemia. If the mare must remain in the stall because the foal is ill, the mare’s uterus should be evaluated daily for fluid accumulation. If fluid accumulates, lavaging her uterus with large volumes of warm saline until the efflux is clear followed by administration of 10 to 20 units of oxytocin has been helpful in preventing metritis.

For the first few days after foaling, feeding should be light to moderate, and laxative feeds such as bran mashes are appropriate to reduce the incidence of constipation.² Routine care of the mare post partum should include essential preventive medicine procedures. In the ideal situation, mares will have received routine vaccinations for the common infectious diseases during the last month of gestation. This allows maximum protection for the foal by way of colostrum. When vaccination history is vague or absent, the mare should be simultaneously vaccinated with tetanus antitoxin and toxoid, at different sites.

Most broodmares on well-managed farms are on a parasite control program whereby antiparasiticals are given every 45 to 60 days. If the mare is not on a bimonthly program and has not been dewormed during the last 2 months of gestation, she should be dewormed within a few days of foaling. Broad-spectrum antiparasitical compounds such as ivermectin are best. Then, an intensive parasite control program, preferably deworming every 45 days, should be implemented.

Mares with a history of a Caslick’s operation as an essential part of infertility management should be resutured as soon as practical. If performed within 15 minutes of parturition, local anesthesia is not required. If the mare tears the dorsal commissure of her vulva and it is not sutured immediately, it is best to keep the area clean until it is sutured in 3 to 4 days. If it is sutured when inflammation is maximal, 24 to 48 hours after parturition, it will likely dehisce.³

COLOSTRUM MANAGEMENT

As the foal depends on absorption of adequate quantities of colostral immunoglobulin for protection against disease during the first month of life, the quality and quantity of colostrum needs to be assessed. Colostrum with a high immunoglobulin concentration is thick and sticky with either a yellow- or gray-tinged appearance. Immunoglobulin content can be estimated by measuring the colostral specific gravity. However the equine colostrometer (Lane Manufacturing, Loveland, CO) developed for measuring specific gravity is difficult to obtain commercially. A colostral specific gravity of 1.06 or greater correlates with a colostral IgG content of greater than 3000 mg of IgG/dl (30 G/L). Foals that suckle colostrum with a specific gravity over 1.06 rarely exhibit failure of passive transfer and have serum IgG concentrations above 400 mg/dl at 24 hours of age.⁴ Colostral quality can also be estimated with a sugar (Bellingham & Stanley, Inc., 5815 Live Oak Parkway, Suite 2C, Norcross, Atlanta, GA 30093) or an alcohol refractometer.⁵ The alcohol refractometer is used to measure the percentage of alcohol in wine by wine makers and is readily available. Colostrum with a level of 6000 mg of IgG/dl (60 g/L) read 16% with the alcohol and 23% with the sugar refractometer.

Colostrum with a specific gravity above 1.07 or with a 16% reading from the alcohol refractometer or 23% with the sugar refractometer may be saved for a colostrum bank. Two hundred fifty milliliters can be collected from the udder after the foal first sucks. The colostrum should be tested for isoantibodies to ensure that the foal that receives the banked colostrum does not develop neonatal isoerythrolysis. Colostrum can be stored in clean labeled containers in a refrigerator freezer (−5° C) for approximately 18 months without degradation of the IgG. Frozen colostrum can be thawed in warm water or in a microwave on the defrost cycle.

TREATMENT OF MARES WITH POSTPARTUM COMPLICATIONS

Postpartum mares that are ill will usually exhibit signs of abdominal pain or depression. Examination of these mares must include a complete physical, transrectal palpation of the reproductive tract and manual vaginal examination. Transabdominal or transrectal ultrasonography can be used to identify a ruptured bowel or uterus, the presence of free blood or feces in the abdomen, or peritonitis. Ancillary clinicopathologic tests should include a complete blood count, serum electrolyte determinations, and in patients in which internal bleeding or compromised bowel function is suspected, abdominocentesis and cytologic evaluation of the fluid obtained.

Diagnosis is often difficult because the clinical signs of many postpartum problems are nonspecific. Abdominal pain is the most common clinical sign of periparturient mares experiencing difficulty. This sign frequently occurs in foaling mares undergoing normal uterine involution and expulsion of the placenta. However, because of the incidence of complications, the following differential diagnoses must be considered in mares showing signs of abdominal pain after foaling: internal hemorrhage from rupture of the uterine artery or uterus; rupture of the cecum, stomach, or right ventral colon; ischemic necro sis of the small colon; colonic torsion; uterine torsion; retained placenta; and rupture of the urinary bladder or diaphragm.

Depression may follow a course of abdominal pain and may be the only clinical finding, especially if the mare has ruptured a viscus or has septic metritis.³ These conditions can usually be differentiated by physical examination, complete blood count, and abdominocentesis.

Postpartum Hemorrhage

Hemorrhage from a uterine artery is common in older mares and is a cause of death in a significant number of aged broodmares.² Multiparous mares over 10 years of age are primarily affected; however, postpartum hemorrhage may occur in young mares as well. Hemorrhage from the artery is not always fatal. It may slowly dissect into the broad ligament or between the myometrium and the serosa of the uterus, forming a hematoma. The resulting clot stops the arterial bleeding and the mare may not exsanguinate. If the broad ligament ruptures or the serosal surface of the uterus tears during formation of the hematoma, the mare quickly bleeds to death.

Mares that bleed into the broad ligament display signs of colic. As tension increases on the broad ligament and the uterine serosa stretches, the mare sweats, the pulse rate increases, and the mucous membranes become pale. Signs of colic may go unobserved, if parturition has been normal and it is assumed that the mare is exhibiting pain from normal postfoaling uterine contractions. Many mares with postpartum hemorrhage are not discovered until they are weak or dead.

Hemorrhage into the broad ligament can be diagnosed by transrectal palpation of the uterus and ipsilateral broad ligament and ovary or by transabdominal ultrasonography of the caudal abdomen. Palpation causes extreme discomfort, and the degree of enlargement of the uterus indicates the extent of hemorrhage.

Mares that have uterine artery tears do not always have a low packed cell volume (PCV) early in the course of disease because the spleen may contract and thereby increase the number of red blood cells in the intravascular space. The PCV of peritoneal fluid may range from 15% to 50%, depending on the amount of blood that has leaked into the peritoneal cavity. Mares with a ruptured uterus may also exhibit blood in the peritoneal tap. Over time, these mares exhibit an increase in number of white blood cells and possibly bacteria in their peritoneal fluid.

The most successful treatment consists of confining the mare to a dark, quiet stall, using mild sedation if necessary. Blood transfusions, plasma volume expanders, and fluid therapy do not seem to alter the course of many cases and may even be contraindicated if the mare becomes excited by treatment procedures. Administration of naloxone (8–32 mg) or formalin (10 ml) in 500 ml of saline intravenously has gained popularity as a treatment for controlling hemorrhage in the postpartum mare, but the efficacy of these treatments is not clear. The recommended dose of naloxone is not sufficient to stop hemorrhage but at the low dose mares experience a profound relaxation.

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