What is it?
Equine Influenza is a highly contagious infectious disease which affects the upper respiratory tract of horses. There have been sporadic outbreaks in the UK in recent years.
What are the clinical signs?
Horses exhibiting clinical signs should be isolated immediately until the cause can be determined.
Clinical signs and symptoms:
- Fever, over 38.5 0C, lethargy, anorexia (off feed), muscle pain/weakness (stiff gait).
- Dry, harsh to hacking cough usually precedes fever. Cough can last up to 6 weeks after all other clinical signs have abated. Influenza should be suspected when multiple horses in a group develop a sudden onset of hacking cough with at least some of the horses having a fever.
- Nasal discharge is initially serous (clear, watery) but occasionally may become mucopurulent (yellow or white) with secondary bacterial infections.
- Secondary bacterial infections are common in horses with influenza.
- Slightly enlarged and mildly painful lymph nodes around the head and neck area.
- Rarely, clinical signs can include swelling of the lower legs and decreased heart function.
How is it spread?
Similar to human flu, equine flu is very contagious. It spreads rapidly by airborne transmission when the virus is released into the atmosphere as droplets by infected animals coughing or snorting. The virus can spread over longer distances than some other diseases, so any infected animal needs to be isolated by 100m to reduce the risk of airborne spread. The flu virus can also live on surfaces and objects that have been contaminated by these droplets. Humans can spread the virus from horse to
horse by contaminated hands and clothing. Using disinfectants can help to manage the risk of spread in this way.
The incubation period can be short as 24 hours and may be up to 3 days. The clinical signs usually appear within 1–5 days of exposure to the flu virus and they can last for 3–6 weeks. Respiratory shedding typically lasts for 7-10 days post infection in horses who were infected for the first time or were unvaccinated. Shedding period is much shorter in partially immune horses (previously infected or vaccinated). Horses rarely shed virus after the resolution of clinical signs.
What should I be doing?
Be vigilant for any of the above signs and call Fellowes Farm immediately if you have any concerns. 01487 773333
Vaccinate. If your horse has not had a flu vaccination in the last 6 months, one should be given now.
Isolate any new horses on a yard for 14 days.
Reduce movement of horses in accordance with advice from authorities such as BHA, BE, BD etc
Primary mode of prevention is vaccination. Horses with ongoing risk of exposure should be vaccinated every 6 months.
Maintaining good hygiene on your yard can help to prevent the spread of equine flu. This includes:
- Taking your horse’s temperature regularly so that you can tell when it is higher than normal
- Isolating new horses
- Disinfecting vehicles and ensuring horses do not share haynets, feed bowls and other equipment.
Having a yard health plan for everyone to follow will reduce the risk of equine flu and other infectious diseases being introduced to the premises, and good hygiene can minimise the risk of infections being spread between horses.
Treatment and management:
The prognosis is good and only rarely does an equine influenza infection result in a fatal outcome. Supportive care and rest are the chief treatments. Non-steroidal antiinflammatory medications are used to control fever, pain, inflammation and improve feed consumption. Antibiotics are often indicated as secondary bacterial infections are common. However, the recovery time for mildly affected horses is usually 2-3 weeks, whilst the recovery period for severely affected horses can be as long as 6 months. Horses affected with Influenza should be restricted from all strenuous activity for at least three weeks in order to allow healing of the respiratory epithelium (tissue that protects the respiratory tract). During that time, horses are extremely susceptible to development of secondary bacterial complications such as pneumonia. If horses are not given adequate rest and appropriate management they can develop chronic reactive airway disease which can compromise their future performance.