Dourine

Managing Dourine

Do’s and Don’ts

Know the visual signs that indicate dourine.

Check the status of your horses. Get horses tested by IVM.

Contact your local veterinarian if you suspect dourine.

DON’T import horses without certificate of disease free – especially dourine.

DON’T use infected stallions for stud services.

Let’s Eliminate Dourine

Background

Dourine is a venereal disease of horses, locally sometimes called “horse HIV”. It is transmitted through mating and infects both mares and stallions.

The Mongolian name comes from… The English name “dourine” originates from Arabic meaning “unclean”. The disease is caused by Trypanosoma equiperdum – a single cell parasitic organism – and is related to diseases like sleeping sickness in Africa.

Although eradicated in North American, Australia and most of Europe, the disease is of growing important in Mongolia. Extensive research has been conducted by Dr. Battur Banzragch and experts at the Institute of Veterinary Medicine (IVM) at the Mongolian University of Life Sciences in Ulaanbaatar with experts from Obihiro University in Hokkaido, Japan with support of MULS and JICA. Their research shows that almost 1 in 12 horses (8%) on average are infected with dourine nationwide. From 3 million horses, this means about 240,000 horses are infected and likely to be spreading the disease. In some aimags, infection rates are very high – Tuv aimag was highest with 41.5% of all horses tested (Narantsatsral S. et. al. 2016)

There is no cure for dourine. Some treatments reduce the effects but do not eliminate dourine from the horses. According to Dr. Battur and his research team in 2016, up to half of infected horses are likely to die and abortion and infertility occurs.  Even if the no death occurs, the horse may still be infective.

The best management of the disease is to know the disease status of each animal and prevent mating with non-infected animals to stop spreading the disease. In some countries, infected animals are immediately euthanized. All imported animals should be quarantined and tested.

The Clinical Signs of dourine are the changes you can see from physical inspection. The time between infection from mating and seeing Clinical Signs is called the Incubation Period. The time of the Incubation Period is variable. It may be as short as 1-2 weeks or as long as several years according to research by William and Steven (2007). The Clinical Signs may also be visible for a while and then decline but return again. This can occur several times before the animal dies or appears to recovery. But the recovery is not complete as the animal is still with the disease and can still transmit the disease. Dourine can kill up to half the infected animals (up to 50% mortality rate) (Sidney et al. 2013). The Clinical Signs include:

 

Some researchers, as reported by Claes and others in 2005 (see also OIE), identified three phases:

 

Stage 1: Genital swelling and water retention (“edema”) manifesting 1–2 weeks after infection

Stage 2: Skin changes – thickening of the skin in round areas (cutaneous signs – edematous plaque) usually over the ribs although may occur anywhere on the body for 3 to 7 days. This is a clear sign for dourine (pathognomonic). Depigmentation of the genital area, perineum, and udder may occur

Stage 3: nervous system clinical signs including neurological disorders such as facial paralysis and partial paralysis (paresis) of the hind legs (hindquarters), with progressive anaemia and amaciation and abortions. Pyrexia (=fever) is intermittent; nervous signs include incoordination, mainly of the hind limbs, lips, nostrils, ears, and throat.

 

These signs are not always visible at different stages of the disease. Eventually dourine will kill the infected horse.

 

The best way to test a suspected animal is with a test from IVM with laboratory testing. The IVM and JICA team are preparing a rapid diagnostic tool for field use as well. This rapid diagnostic will allow identification of infected animals quickly and simply in field conditions. The expected cost of testing one animal is 3000 MNT..