Breeding Season Biosecurity
For horse breeders, August heralds the excitement of the beginning of a new foal crop arriving but sometimes the unexpected happens. Not all pregnancies end with a lovely healthy foal. Irregularly mares can abort, or give birth to a stillborn or weak foal. Infection of the mare with equine herpes virus or leptospirosis are two potential reasons for this outcome. Herpes and Lepto are both common organisms circulating in New Zealand and if your mare has aborted or if your foal is weak or dies early then this is when good biosecurity practises as listed below can prevent you or other horses also getting infected. During this period, people are more likely to come into contact with birthing fluids and unwell mares and foals and leptospirosis can cause severe illness and even death in people so horse handlers should be extra vigilant with their hygiene. This period also sees increased movement and interaction among horses. This increased mingling heightens the risk of disease transmission especially if one of the individuals is actively shedding equine herpes virus.
At least a quarter of all horses in New Zealand have evidence of exposure to leptospirosis. Not all strains of leptospirosis make horses sick, but some can.
Most mares were first infected with Equine Herpes Virus in their early years, however after overcoming this spell of early infection the virus migrates into nervous tissue and remains latent in the body until the virus is activated in times of stress such as late pregnancy, travel, adverse weather or during the stress of mixing with new paddockmates
Here are some key points to consider, focusing on personal protective equipment (PPE) for horse careers, biosecurity around horse-to-horse contact, and horse movement.
Personal Protective Equipment (PPE)
Diseases that can be transmitted between horses and people, like leptospirosis, are called zoonosis. So practising good biosecurity not only limits you spreading disease to other horses but prevents you becoming infected.
Using appropriate PPE is essential for anyone handling horses during the breeding season. Best practice includes wearing gloves, disposable footwear, and coveralls to prevent the spread of disease. People should change gloves and wash their hands thoroughly between handling different horses to avoid cross-contamination. Foot baths with disinfectant can be used to clean footwear before entering and exiting stables or paddocks.
Adding additional PPE to your normal routine during the breeding season can protect you and your horses from disease.
Movement of Horses During Breeding Season
The breeding season often involves increased movement of horses, whether it is mares travelling for foaling, or for mating, or the importation of shuttle stallions. This increased movement can elevate the risk of disease spread.
It is important to consider the biosecurity measures associated with horse movement to manage this. Horses should be transported in clean, disinfected horse floats or trucks. Mares should be in good health before they travel, including being up to date on vaccinations.
It is advisable to avoid mixing horses from different farms during transport. Direct horse-to-horse contact is a significant route for disease spread, with nose-to-nose contact a high risk.
Upon arrival at a new location, where possible, mares should be isolated for a period of time to monitor for any signs of illness. Mares should be kept in separate paddocks to prevent nose-to-nose contact. Alternatively, keeping mares in smaller herds based when they arrived on the farm can reduce the risk of disease spread beyond a small group. Shared equipment, such as buckets, brushes, and halters, should be thoroughly disinfected regularly or, ideally, each horse or group of horses should have its own set of equipment. Horse carers should be vigilant for any signs of illness after transport and take immediate action if any symptoms are observed.
Case study: Protect yourself (and your horse) during the breeding season
Early one spring morning, Anna was helping her mare, Bella, deliver a foal. The birth went smoothly, and soon a beautiful, healthy foal was standing on wobbly legs. As Anna cleaned up the afterbirth and tended to the foal, she noticed a small cut on her hand. She didn’t think much of it and continued her work, ensuring both Bella and the foal were comfortable.
A few days later, Anna started feeling unwell. She had a high fever, severe headaches, and muscle aches. Initially, she thought it was just the flu, but her symptoms worsened. Concerned, Anna visited her doctor, who ran some tests and diagnosed her with leptospirosis.
The doctor explained that leptospirosis is a bacterial infection caused by the Leptospira bacteria. People can contract leptospirosis through direct contact with infected animals or their bodily fluids, including urine and reproductive fluids. Handling horse afterbirth or a foal can pose a risk if the horse is infected with Leptospira. In Anna’s case, it was likely she got infected while handling the afterbirth and the foal, as horses can carry the Leptospira bacteria.
Bella and the new foal did not seem to be unwell, as the symptoms of leptospirosis in horses can be subtle. However, following her diagnosis Anna called her vet to test Bella and her new foal for lepto, and Bella was positive! The symptoms of lepto can cause placentitis (infection of the placenta) or abortion, but luckily these hadn’t occurred in Bella’s case. Other symptoms can include a fever, lack of appetite, uveitis (inflammation of the eye), blood in the urine, jaundice (yellowing of the skin and/ro eyes), and in extreme cases, kidney and liver failure.
Anna was prescribed antibiotics and advised to rest. She also learned the importance of wearing protective gear, like gloves, when handling potentially contaminated materials in the future. After a few weeks of treatment, Anna recovered fully and returned to her horses, now more cautious and informed about the risks.Like Anna, Bella and her foal received treatment for the infection from the vet and are now back to normal and not infectious to other horses or people.
If you suspect that you have been exposed to leptospirosis, it’s crucial to seek medical attention promptly for appropriate testing and treatment.
If your mare aborts during her pregnancy, it is important to be aware that the birthing fluids can be a risk to human health, and that abortion may be an indication of an infection with a disease like lepto, or a virus like EHV-1. NZEHA recommend that all abortions are investigated by your veterinarian and request samples are analysed for Herpes or leptospirosis.
Conclusion
Implementing biosecurity measures during the breeding season is essential to protect the health of horses and people. By using appropriate PPE, preventing direct horse-to-horse contact, and carefully managing the movement of horses, the risk of disease transmission can be significantly reduced.
Feel free to contact the NZEHA for support and advice around biosecurity during the breeding season
