This disease is specific to equids and develops generally in a benign way with the symptoms of influenza. The infection is dreaded in the equids's breeding areas because it releases an epidemic abortions.
The infected stallions can excrete the virus in their sperm over many years even their whole life.
In France the rate of infected equids is estimated at 2%.

Contamination

The mode of transmission for arthritis is the infectious sperm, or direct contact or aerogene. Blood, urine, faeces, lachrymal and vaginal secretions also contribute to the propagation of the disease.
The infected stallions play a central epidemiologic part, as virus stock; as they can excrete the virus during a very long time, the stallions used for artificial insemination must be particularly supervised.

Symptoms

In the majority of the cases, the donkey infected by the virus will not present any symptoms, and only the examinations in laboratories can diagnose the disease.

When the animals are more fragile (ex: age), or original cell is stronger, certain clinical signs can appear, sometimes resulting in death for the oldest animals or very young foals:
- strong fever over several days
- intense tiredness
- loss of appetite
- oedemas on the hind limbs, around the eyes and on the abdomen
- nasal secretions and/or eyes, conjunctivitis, rhinitis
- urticaria

But the most serious consequence of this disease is that it can involve an abortion of the foal (between 10% and 70% cases). If the infection takes place at the end of the gestation, the foal develops an acute respiratory form of the disease.
The stallions having contracted the disease can excrete the virus in their sperm over weeks, even years, and thus contaminate the mare during the covering.

Prevention

There are no specific treatments for this disease, apart from the treatments which must be applied according to the symptoms.
The prevention and the isolation of the sick animals can help to avoid the infection propagation.