12/08/2026
With breeding season starting this month, now is the perfect time to refresh yourself about diseases that can affect broodmares🐴 🦠
Today we are going to focus on Equine Herpesvirus Type 1 (EHV-1) and Strangles (Streptococcus equi, subspecies equi).
EHV-1 is a serious threat to broodmares, known for causing late-term abortions, neonatal foal death, and neurological disease. Prevention is key, and that starts with vaccination, supported by on farm biosecurity.
EHV-1 can linger silently in horses and re-emerge under stress. Staying ahead with proactive care keeps your mares - and foals - safe.
While EHV-1 is particularly serious in broodmares due to the risk of late-term abortion, any horse under stress: whether from travel, illness, social stressors, or environmental changes, can shed the virus. This shedding can occur even in horses that appear healthy, making them silent carriers and a potential source of infection for others in the herd. That’s why biosecurity and vaccination protocols are essential not just for pregnant mares, but for all horses on the property.
Vaccination Matters - Broodmares should be vaccinated at 5, 7, and 9 months of gestation using a vaccine specifically labelled for abortion protection. Annual boosters for all horses on the property help reduce viral shedding and protect the herd.
Strangles is one of the most contagious bacterial diseases of horses and can spread quickly through breeding farms, agistment properties, sales complexes, and youngstock operations. Foals, weanlings, and yearlings are particularly susceptible, and outbreaks can lead to illness, disrupted training and sales preparation, and can have significant management costs.
Strangles spreads easily through direct horse-to-horse contact, as well as contaminated equipment, water sources, vehicles, clothing, and handlers. Good biosecurity practices, including quarantine of new arrivals, monitoring horses for fever, and prompt isolation of sick horses, are essential for reducing the risk of an outbreak.
While young horses are often most affected, any horse can become infected and some may continue to carry the bacteria after they appear clinically recovered. These silent carriers can unknowingly introduce infection into a herd, making veterinary testing and strong biosecurity protocols important for all horses on the property.
Vaccination can help reduce the severity of disease and decrease bacterial shedding, making it a useful tool for properties with a higher risk of exposure. Broodmares should have a strangles (and tetanus) booster four to six weeks before foaling.
