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Routine Vaccination of Foals

Vaccination is a vital part of these equine health management programs for both mares and foals.

Vaccination of the mare to boost her immunity will ensure that her new foal also has an adequate level of protection, known as maternally-derived antibodies. These are immunologically active substances that are delivered to the foal in the mare’s colostrum during the first 24 hours of life.

To provide adequate protection against disease foals need to receive their vaccinations once maternally-derived antibodies begin to wane. This coincides with the foal being around 3-4 months of age. Therefore, it's important that foals have their own health management program to ensure that they are protected against disease and thrive. For convenience sake, many will start the vaccination program at weaning time, this being anywhere from 4-6mths of age.

Tetanus and Strangles

Clinical signs and transmission of Tetanus and Strangles were discussed in our previous article, Routine Vaccination in Horses - Tetanus and Strangles.

The following vaccine protocols are recommended for foals:

Then a Strangles Tetanus combined 2 in 1 booster annually.

Equine Herpes Virus-1,4

There are 5 strains of Equine Herves Virus (EHV) that affect domestic horses, of which EHV-1 and EHV-4 can cause respiratory disease, neurological disease and abortion in pregnant mares. EHV-1 being the highly contagious strain that can result in abortion storms and/or birth of weak, nonviable foals. EHV-1 is responsible for most late gestation abortions (>7months). You can learn more about EHV-1 disease and vaccination in our article on vaccinations for broodmares.

Clinical signs of EHV infection in foals include fever, coughing and clear nasal discharge. Some horses may develop neurological signs leading to lack of coordination, weakness, difficulty in urinating and defecating. They may even become recumbent and unable to stand. Infected horses can develop complications such as secondary bacterial infections.

Mares that abort due to EHV infection shed large volumes of virus into the environment via the foetus, placenta and foetal fluids. The virus can be transmitted through the air from horse to horse up to distances of 5 metres, usually through close contact and coughing. EHV can also be transmitted on clothing and yard equipment by people working with infected horses.

Horses can be asymptomatic carriers of the disease, shedding the virus that may infect other horses without appearing clinically ill at the time.

Vaccination of foals against EHV-1 and EHV-4 is recommended as it can help to reduce the shedding of the virus, its transmission to other horses and the severity of the respiratory form of the disease. It must be remembered that vaccination does not provide absolute protection and further preventative measures must be followed.

Equine Salmonella Vaccination

Salmonella is a highly contagious disease that causes severe life-threatening diarrhoea. It can be a difficult disease to treat and in foals can also result in osteomyelitis (bone infections). Salmonella is particularly difficult to control and prevent as it is widespread in the environment and in faeces of healthy horses. Infection and outbreaks are often dependent on the virulence of the particular strain.

Transmission can occur via contamination from the environment, feed, or water or by contact with animals actively shedding the bacteria. Animals who are experiencing some sort of stress are most prone to development of salmonellosis.

Hendra Vaccination

For foals born to mares who received Hendra Vaccine, start their vaccine program at 6 months of age, otherwise start at 4 months.

The vaccination protocols discussed here are a guide only. Your veterinarian is the best source of information for your unique situation. Once your foal reaches 12-18 months of age, they will need to move onto a routine vaccination program.

About the author

Dr Leigh Davidson BVSc, BApplSc

Director at Your Vet Online

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