Contagious equine metritis: experimental infection in the donkey.

This research article investigates the infection of Contagious Equine Metritis (CEM), a sexually transmitted disease in horses, in donkeys. The study found that the donkeys were susceptible to the disease, showing similar symptoms to horses, and may potentially act as a source of infection.

Experiment Design and Results

• The study reproduced Contagious Equine Metritis in 3 out of the 4 studied donkey mares, using a strain of Haemophilus equigenitalis. This bacterial strain was isolated from an experimental case of the disease in a pony mare.
• The clinical response of the infected donkeys was found to be variable, showing amounts of vaginal discharge and inflammatory changes of the vagina and cervix, similar to symptoms observed in horses. However, the study did not find any evidence that semen enhanced the clinical severity of the infection in the donkeys.
• All infected donkeys made spontaneous clinical recovery and persistence of the bacterium H. equigenitalis in the genital tract was of limited duration. These findings suggest that the infection in donkeys is self-limiting, meaning the body can recover from it without treatment, in a certain time frame.

Diagnostic Methods and Serological Response

• Cytological examination of swabs was only of diagnostic value during the clinical phase of the infection. This means that tests done after this phase may not be able to detect the bacterium, limiting its diagnostic use.
• By conducting serological tests, which are tests carried out on blood sera, the study detected indications of the body’s response to the infection. However, these responses were described as “low magnitude” and short-lived. This implies that although the infection triggered an immune response, it was not intense or long-lasting.
• Despite limitations including low levels of non-specific reactivity and pronounced anti-complementary reactivity, the passive haemagglutination test was superior in demonstrating an elevation in antibodies and confirming infection.

Potential Role of Donkeys in CEM Transmission

• The overall conclusion of the study indicates that donkeys have the potential to act as a source of infection for Contagious equine metritis. This provides an important insight into the disease’s epidemiology, opening up possibilities for further research into how the disease is transmitted and propagated.
• The results of the study suggest that under certain circumstances, donkeys could play a role in spreading the disease. However, the exact factors leading to this potential role were not specified and might be the subject of further study.