Besnoitiosis Benetti – An Emerging Parasite in Miniature Donkeys
Below is a very basic overview of the ailment. Besnoitiosis Bennetti is often referred to as a skin disorder impacting horses and donkeys. For some reason, Donkeys seem to be more susceptible to the disorder. The disorder was first discovered by S.C.J. Bennett while on an expedition to Sudan when he found 4 horses with cysts. The first case of Besnoitiosis Bennetti in the United States was found in a herd of Mexican Burros in 1973 owned by the USDA.
In 2005, 14 Miniature Donkeys in a mid-Michigan herd of 38 presented with clinical signs of Besnoitiosis. Inspection of the Donkeys resulted in the findings of ocular sclera (or cysts), nasal sclera and dermatitis in various areas of the body. We had a discussion with one of the researchers, Charles Mackenzie who stated that he personally took the worst-case Miniature Donkey home and over a very extended period of time, the animal recovered.
In 2011, an 18 month old Miniature Donkey jack and a 2 year old Poitou jennet, afflicted with Besnoitiosis Bennetti were donated to Cornell University to conduct clinical trials.
Besnoitiosis Bennetti is not ONLY a “skin” disease that is a mere nuisance or causes cosmetics changes to the epidermis. This disease starts at the epidermis and has the ability to travel further through the body. It is believed this single-cell parasite enters the donkey’s system through grazing, similar to EPM (equine protozoal myeloencephalitis). There also has been evidence that the disease may be transmitted between animals, source of transmission unknown.
EPM has a complex life cycle. The Opossum is the definitive host, which sheds infective sporocysts in their feces. Intermediate hosts are skunks, raccoons and cats who can become infected and develop sacrocists in their muscles. Horses ingest the infected sporocyst which matures and migrates to the horses’ central nervous system damaging tissue.
The life cycle for Besnoitiosis Bennetti in unknown, Despite numerous experiments over the years, researchers still are unable to isolate which animal(s) are the definitive host.
What we do know:
- Besnoitiosis Bennetti shows in a variety of ways; sclera or white cysts on the white portion of the eyes, sclera on the eyelids, small sclera in the nasal passages, crusty abrasions in many cases, located in the genital area, white cysts appearing in the esophagus when scoped, and presented in a jack in the testicles when gelded.
- Besnoitiosis Bennetti seems to afflict younger animals who have not reached maturity, typically weanlings to 3 years of age.
- There have been cases that as the immune system develops, the body has been able to fight off the parasite.
- Researchers have used EPM treatments for a limited period of time: Ponazuril (Marquis), Diclazuril and Sulfadiazine/Pyrimethamine and did not conclude that these medications helped in the treatment of Besnoitiosis Bennetti.
- It is believed it can be transmitted between animals, source is not known. A couple of researchers feel it could be insects.
- In 2020, the first record of Besnoitiosis Bennetti in the UK was reported.
