Herpes Virus – To Vaccinate Or Not To Vaccinate?

Herpes Virus causes a number of different conditions. In humans it causes cold sores and in horses respiratory infections, neurologic disease and abortions. The virus is species specific, so if you have a cold sore you can’t give it to your horse and vice-versa. The infection is life long and over 80% of horses carry the herpes virus. The virus may remain latent for long periods of time and then during periods of stress the virus becomes active causing disease or is shed and spread to other horses. 3 Types of Equine Herpes Virus(EHV) are known to cause disease in horses:

• EHV1 – respiratory disease, neurologic disease, abortions and death in new born foals.
• EHV3 – Equine Coital Exanthema (a superficial venereal disease on the genitalia of affected horses)
• EHV4 – Rhinopneumonitis (upper respiratory disease in young horses). Rarely a cause of abortions and neurological disease.

Abortions usually occur in the last trimester of pregnancy and present a fresh foetus and placenta. The fluids and placenta contain high levels of virus and are prime sources of the virus spreading it to other horses. The abortions can be sporadic or occur as abortion storms. Foals can be born alive but with extensive damage to their organs, these foals rarely survive despite the best treatment.

Vaccination against EHV is available and it is relatively inexpensive compared to the cost of losing foals, treatment of affected horses, quarantine measures and lost breeding opportunities due to quarantine. The vaccine used most commonly in RSA against abortions is Pneumabort K (Pfizer). 2ml are given IM in the 5th, 7th and 9th months of pregnancy.

Against the rhinopneumonitis syndrome there is a vaccination called Resequin(Intervet). Resequin is an inactivated EHV1 and EHV4 combined with an Equine Influenza vaccination. This is used mostly in young horses in training or sales preparation to prevent the mild respiratory disease caused by EHV1&4. When using it be sure to vaccinate against Tetanus as it is not included in this vaccine.

It is important to note that like any vaccination the aim of the vaccine is to stimulate the animal’s immune system such that it is able to more effectively fight the infection when faced with it. It will not prevent every single EHV infection and abortions may still occur, but fewer of them and not as an outbreak. It is therefore important to continue to maintain good management practices. i.e. Quarantine new arrivals for 28 days, don’t mix mares unnecessarily, group new arrivals as a group and don’t integrate them into the other resident mares until the beginning of their next pregnancy. Minimise all forms of stress.

Bosch Hoek Equine Hospital is a state of the art Equine hospital situated in the beautiful Kwa-Zulu Natal Midlands of South Africa. Our primary goal is to offer clients and their horses world class care and expertise for both surgical and medical conditions with a rehabilitation centre to match.

If you require our services or would like to discuss anything please call one of us on the numbers below:

Dr Helen Tiffin 082 966 9324
Dr Jenny Lawrence 082 836 9897 (away until 14 March)
Dr Anna Bowker 082 849 3456 (away until August)
Dr John Hodsdon 072 165 7122

Dr Helen Tiffin Equine Veterinarian Born with a passion for horses, Helen worked in the equine industry for several years before studying to become an Equine Veterinarian. After qualifying in 2004, Helen began work with the Equine Research Centre in Pretoria. In 2005 she joined Dave Mullin’s practice in the KZN Midlands where she became a valuable asset to the equine community. In 2010 Helen took on partnership in Bosch Hoek Equine hospital where she is the resident veterinarian. Helen has continued riding throughout and competes regularly at local events when time allows.