Leptospirosis and embryo recovery rate in mares.

This research investigates the link between Leptospirosis, a bacterial disease, and low embryo recovery rates in mares (female horses) in Rio de Janeiro, Brazil. The researchers did not find a significant association between the disease and embryo recovery rates.

Study Overview

• Of reproductive significance in horses, leptospirosis can cause stillbirth and abortions. However, its influence on the embryo recovery rate in mares remains largely unexplored, motivating this study. Embryo recovery refers to the process of collecting embryos from a donor mare, crucial for horse breeding – optimizing superior genotypes and facilitating the birth of more foals per year from a single mare.
• Mares from nine different groups in Rio de Janeiro, Brazil were studied. The 80 mares selected had a history of low embryo recovery and were not vaccinated against leptospirosis. However, they had received veterinary care and individual reproductive monitoring, and were vaccinated against equine rhinopneumonitis virus.

Methodology and Findings

• Blood samples from the mares were taken, and a serological survey was performed for leptospirosis. Serology involves studying blood serum to investigate immune responses to pathogens.
• The standard test for detecting leptospirosis, known as the Microscopic Agglutination Test (MAT), was used. A reactive titre or concentration of 200 or more was considered positive for leptospirosis.
• 62.5% of the mares were found reactive to Leptospira species, the bacteria causing leptospirosis. The most common variety detected was Bratislava (76%), while Copenhageni was seen in 24% of the positive mares.
• A failure rate of 26.2% in embryo recovery was observed in mares with normal ovulation and no clinical signs of endometritis, an inflammation of the uterine lining.
• Despite the high prevalence of leptospirosis, no significant link was found between the infection and embryo recovery failure.

Study Limitations and Recommendations

• The MAT test used in this study may not always provide a clear interpretation, particularly in chronic or subclinical infections.
• Researchers suggest that paired serology or direct methods, such as culture or PCR testing, may be necessary to confirm the infection.
• Although the researched mares didn’t undergo these tests, it is worth to mention that leptospirosis is often subclinical in horses.
• Therefore, it is recommended that animals exposed to areas endemic to leptospirosis should be tested for the disease, even if they have low titres.