INFORMATION ON EQUINE VACCINATION COURSES
Equine Herpes Virus (EHV type 1 and 4)
Which horses should be vaccinated and what does it involve?
Any horse or pony can be vaccinated from 5 months of age onwards. An initial course involves an
intramuscular vaccination which is repeated after a 4-6 week interval. From then on a booster should
be given every 6 months to maintain immunity to infection. In the normal horse, the virus often goes
unnoticed, but it can cause a respiratory infection and present with fever, depression and clear nasal
discharge. It is therefore not essential to vaccinate every horse against Herpes virus, but there are
some high risk groups for which you should strongly consider vaccination.
Pregnant Mares : Pregnant mares which become infected with equine herpes type 1 and 4 are at risk
of abortion. They usually catch the virus when mixing with younger animals, which is why pregnant
mares should ideally be kept in small groups and away from young animals and any animals coming in
from other properties. Pregnant mares should receive a vaccination at the 5th, 7th, 9th (and 11th if not
foaled) months of pregnancy to help minimise the risk of abortion and severe illness in the newborn
foal.
Horses in Competition: Horses which are mixing with others at competition are at a
relatively high risk of picking up infectious diseases. When combined with travelling long distances
these viruses can make the horse quite ill and more prone to bacterial infection as well.
Some horses can show a fever and depression after vaccination, so it is advisable to monitor
temperature for 24-48hours after vaccination.
Rotavirus Vaccination in Pregnant Mares
Rotavirus is a common cause of scour and severe illness in the newborn foal. In the worst cases it can
Be fatal. Some properties will have a known Rotavirus problem, and these are the places where
vaccination is particularly important. Pregnant mares can be vaccinated at the 8th, 9th and 10th month
of pregnancy to help boost the immunity in the colostrum which will then be transferred to the foal.
The vaccination is effective, but cannot be given within 2 weeks of any other vaccination. As with most
Infectious conditions in the foal, the risk of exposure is minimised by ensuring the mare and foal
live in a clean environment.
Tetanus and Strangles
Both of these equine diseases can be vaccinated for once the horse/pony is more than 5months
of age.
Tetanus is a disease which is commonly fatal in horses. Normally the bacteria, which live in the
environment, gain entry through a wound, and then release a toxin into the blood which affects
nerve function. The nerve damage causes the horse to be stiff, often with a raised tail and locked jaw.
Eventually the disease progresses to affect the nerves responsible for breathing, and horses often do
not recover. Treatment is both expensive and often ineffective. For this reason we strongly
recommend vaccinating all horses against Tetanus. We recommend giving two vaccinations about
a month apart and then giving a booster every two years to maintain a high level of immunity.
Pregnant mares should receive a booster vaccination 4-6weeks before they are due to foal. This
boosts the levels of protection that are passed from the mare to foal in the colostrum.
Side effects to this vaccination are very rare.
Strangles is a bacterial disease which can present in a number of ways. Some horses show hardly any
clinical signs, others show a fever, thick nasal discharge and sometimes enlarged painful
abscesses within the lymph nodes around the throat and under the chin. This latter presentation is
fairly rare these days, but it gave the disease its name of ‘Strangles’ as the abscesses can get so large
that they can restrict the breathing. Vaccination reduces the severity of the clinical signs and
also the amount of bacteria shed from the infected horse, so vaccinated animals are less contagious
than non-vaccinated animals. Pregnant mares can abort if they get Strangles during pregnancy.
There are some side effects to watch out for with the Strangles vaccination. There is a risk of fever
and depression as with other vaccinations, but some horses can develop leg swelling and spots
on their gums as part of a more severe reaction. This latter condition is called ‘purpura
haemorrhagica’ and although it is rare it can make the horse extremely sick so seek urgent
veterinary advice if you suspect this type of reaction in your horse.
The primary course involves giving three strangles vaccinations, each 2-4 weeks apart. We can give
combined Tetanus and Strangles vaccination courses. From then on yearly boosters are given for
Strangles, but for high risk situations/yards we can give boosters every 6 months to try and maintain a
higher level of immunity.