Vaccinations are available for a number of diseases but some are only appropriate for horses that travel overseas for racing and competitions. The two most important vaccinations that every horse should receive are influenza and tetanus.

There are also vaccinations against Strangles and Equine herpesvirus (EHV). EHV can cause abortion in pregnant mares, so contact your vet to discuss this if you are considering breeding from your mare.

Tetanus ('lock jaw')

Tetanus is caused by a bacterium, Clostridium tetani, which is found in soil and enters the horse's bloodstream via an open wound. Even small wounds can allow Clostridium tetani contamination and, because the incubation period is 7-21 days, the wound has usually healed by the time the first signs of the disease are apparent. Often owners are not even aware that their horse has received a wound, or thought it minor and of no importance and yet their horse develops tetanus.

The signs of tetanus are:

• Vague stiffness in the head and limbs progressing to reluctance to move.
• Spasms in the muscles of the head and neck resulting in difficulty chewing, nostril flaring and a wide-eyed expression.
• 'Sardonic smile' - the corners of the mouth are drawn back tightly.
• Erect ears.
• Trembling progressing to violent, whole body spasms in response to sudden movements or noise.

Approximately 90% of unvaccinated horses that develop tetanus die. In the small number of horses that do recover, intensive veterinary treatment and nursing care is required for a period of about 6 weeks.

Equine influenza ('flu')

This is a highly contagious, viral disease of the respiratory system caused by different strains of influenza virus. A horse contracts the virus either through contact with an infected horse, or indirectly by contaminated environments/air. Infected horses incubate the disease for 1-3 days before displaying any symptoms, which is why outbreaks of equine influenza spread so rapidly.
The symptoms of influenza include:

• A rise in temperature up to 41 degrees C (106 degrees F) for 1-3 days (often undetected).
• A harsh, dry cough of sudden onset that persists for 2-3 weeks or more.
• Clear nasal discharge progressing to thick, green-yellow discharge.
• Lethargy.
• Loss of appetite.

The disease can develop into life-threatening bronchitis or pneumonia. When horses recover from influenza, they can be left in a debilitated state making them more susceptible to secondary infections.

Outbreaks of influenza are most common when large numbers of young horses are brought together in stressful conditions, ie sales or shows.

Strangles

Strangles is a bacterial disease caused by Streptococcus equi, affecting lymph nodes. Signs of the disease include a fever, mucopurulent nasal discharge, swollen lymph nodes, depression, off feed. Most horses do recover.

Although vaccination is not 100% efficacious it prevents horses from developing the serious pathologic signs seen in unvaccinated horses, which can lead to death.

EHV

EHV is a highly contagious infection which is a common cause of abortion in pregnant mares. Infection is usually acquired via the respiratory route, either directly by respiratory aeorsols or indirectly via ingestion of infected feed sources/fomites. EHV also causes respiratory tract disease, neurological disease and disease of the neonatal foal. For further information on vaccination against EHV, contact your vet.