What is Miscarriage ?
There are many possible causes of a miscarriage that include infections, such as from a bacteria or virus that can attack both the mare and the fetus, or a fungal poisoning, as in the case of tent caterpillar toxicity. Biological factors such as age, hormone levels and genetic abnormalities can also affect the reproductive system and cause a premature loss of a fetus.
A miscarriage is a spontaneous ejection of a fetus from the mare before it has fully grown. This can occur without any other indication of a problem in a seemingly healthy mare, or there may be accompanying symptoms such as breeding issues, vaginal discharge, or even general illness symptoms, like colic or appetite loss. It is important to discover the cause of the miscarriage, as some conditions can affect future pregnancies.
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Symptoms of Miscarriage in Horses
The main symptom of a miscarriage in horses is:
- Fetus that has been expelled from the mare prematurely
Symptoms associated with the causes of abortion can include:
- Premature lactation
- Vulvar discharge
- Premature separation of the placenta
- Thickened placenta
- Placenta that is heavy, edematous, bloody, or covered in brown mucus
- Retention of placenta after a miscarriage
- Fetal lesions
- Retarded fetus growth
- Swelling of mammary glands
- Swelling of the limbs
- Decreased appetite
- Nasal discharge
- Jaundice in mucous membranes
Causes of Miscarriage in Horses
There are many reasons why a mare could miscarry a fetus. They include:
- Uterine impairment due to aging
- Failure of the pregnancy signal between the embryo and uterus, causing the mare to cycle
- Insufficient hormone levels to maintain pregnancy
- Post-breeding endometritis
- Infectious endometritis, from bacteria such as Streptococcus
- Umbilical cord strangulation of fetus
- Congenital defects of fetus
- Equine viral arteritis
- Equine Herpes Virus
- Potomac horse fever, due to the Ehrlichia risticii bacteria
- Contagious equine metritis, caused by Taylorella equigenitalis
- Bacterial placentitis, caused by a Streptococcus species, Salmonella, Klebsiella, Escherichia coli, or Pseudomonas
- Nocardioform placentitis, caused by Rhodococcus rubropertinctus, Amycolatopsis spp, Nocardia spp, or Crossiella equi
- Equine mycotic placentitis, caused by species of Aspergillus spp, Histoplasma capsulatum, Coccidoides spp, Candida spp, Mucor spp, or Cryptococcus neoformans
- Mare reproductive loss syndrome, caused by tent caterpillar ingestion
- Fescue grass poisoning, caused by the fungi Neotyphodium coenophialum
- Reaction to certain drugs, such as corticosteroids
Diagnosis of Miscarriage in Horses
A diagnosis of miscarriage is made when a fetus has been spontaneously expelled from a mare. Giving the fetus and placenta to your veterinarian can be very helpful in diagnosing why your horse miscarried. Many tests can be performed to determine the cause, ensuring that the proper treatment and prevention of further problems can take place.
A physical exam and a history of any symptoms seen now or in the past can help your veterinarian come to a cause. Tissues of the fetus and placenta are examined, and the blood and stomach contents of the mare may be analyzed too. Other tests include PCR, staining, and fluorescent antibody testing on the mare, and tests on the fetal organs and serology. Several serum tests on the mare may take place and compared if an infectious agent is suspected.
Further tests specific to a suspected condition may also be needed to correctly diagnose the reason behind the miscarriage.
Treatment of Miscarriage in Horses
Treatment for a miscarriage in horses will focus on treating the cause, and can vary based on your horse’s needs. Some cases may not need treatment, such as with equine viral arteritis which can clear up without therapy. If an infection is present, antibiotics, antifungals, or antiparasitics are given as needed, and infectious animals should be kept away from the rest of the population to prevent spreading the infection. An ultrasound can be used to look for signs of infections or fetal abnormalities during pregnancies if your mare is at risk of developing placentitis. Any supportive care is given as needed. Prevention is the best way to ensure that your horse does not contract anything that could compromise pregnancy.
Recovery of Miscarriage in Horses
After a miscarriage, monitor your mare for any other signs of health conditions, taking note of her attitude and appetite. Some symptoms may be a signal of a reproductive problem that needs to be reported to your veterinarian and may affect future breeding for your mare.
Prevent your horse from contracting some of the diseases that can compromise her reproductive health with vaccines, such as for the equine herpes virus. Any infections should be properly managed with disinfectants and practicing good hygiene. Eliminate areas where problems can occur, such as standing water that can breed mosquitoes carrying viruses, or fescue infected grass.