Parasitic disease found in British donkeys

A chronic and potentially debilitating parasitic equine disease which causes cystic lesions in the skin and eyes, has been found in donkeys in the UK for the first time.

The study was carried out by experts from the University of Nottingham and the Donkey Sanctuary. A full report is published in the journal Parasites and Vectors.

Equine besnoitiosis is a disease of donkeys, horses, zebra and mules. Affected donkeys develop multiple nodules in the skin, over the nostrils, ears and face. Cases may show tiny cysts on the surface of the eye. Some infected animals remain otherwise healthy, while others become thin and debilitated. 

The condition has been identified in a growing number of countries. The USA, Africa, Spain, Belgium, Italy, and Portugal are among countries reporting cases in donkeys. In horses, it is found especially in the tropics.

The disease is caused by Besnoitia bennetti, a protozoan parasite whose life cycle is poorly understood. 

The first UK case was identified in 2013, when a donkey at the Donkey Sanctuary was presented with skin lumps. They were initially presumed to be sarcoids, but microscopic examination revealed the presence of cysts typical of those caused by Besnoitia bennetti, along with tissue changes associated with sarcoids.

This case triggered a collaboration between a team of clinicians from the Donkey Sanctuary and a veterinary parasitologist from the School of Veterinary Medicine and Science at the University of Nottingham. Since then 20 clinical cases of this emerging parasitic infection have been identified and studied.

Other than one donkey that had come from Ireland, none of the donkeys included in the study had been abroad.

Dr Rebekah Sullivan, co-author of the report and a vet at the Donkey Sanctuary, said: “Given the relative proximity to other European countries, where clinical besnoitiosis is apparent, our findings will inform British vets of the potential for this emerging disease so that they can better recognise the pattern of clinical signs during clinical examination.”

 “It is absolutely essential – particularly now – that vets in the UK learn more about besnoitiosis, so they can identify and protect donkeys potentially at risk” said Dr Hany Elsheikha, lead author of the study and Associate Professor of Parasitology at the University of Nottingham. “Knowledge obtained in this study should improve our response to this emerging parasitic disease in donkeys in the UK, especially with the few treatment options and the unknown routes of transmission.”

The research team also developed serological and molecular screening methods, which allow earlier diagnosis of the disease.

Gereon Schares from the Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Germany, and co-author of the report,  added: “This study is particularly important because by using a suite of molecular methods we were able to confirm for the first time in Europe that the parasite agent involved in these cases is specifically Besnoitia bennetti and infection can be shown by serological methods.”

The correct identification of Besnoitia cysts in skin biopsies taken from UK allows veterinarians to give a more accurate prognosis. 

“It can no longer be assumed that skin masses are either neoplastic in origin or inflammatory, such as eosinophilic granulomas, for example,” said George Paraschou, co-author and pathologist at the Donkey Sanctuary.

For more details, see:

First record of besnoitiosis caused by Besnoitia bennetti in donkeys from the UK

Hany M. Elsheikha, Gereon Schares, Georgios Paraschou, Rebekah Sullivan and Richard Fox

Parasites Vectors (2020) 13:279

https://doi.org/10.1186/s13071-020-04145-8

Investigating the Arabian genome

A study involving Arabian horses from 12 countries found that some populations maintained more genetic diversity and that the breed did not contribute genetically to the modern-day Thoroughbred, contrary to popular thought.

An international team of scientists was led by the University of Florida’s Samantha Brooks, of the University of Florida, and Doug Antczak and Andy Clark at Cornell University.

The group collected and examined DNA samples from 378 Arabian horses from Qatar, Iran, UAE, Poland, USA, Egypt, Jordan, Kuwait, United Kingdom, Australia, Denmark and Canada. The research is published in the journal “Scientific Reports.”

Other than the horse’s location and whether it was used for endurance, racing or showing, the samples were anonymised for data analysis purposes.

The researchers also incorporated information gained in previous studies, which included breeds such as Thoroughbreds, Persian Arabian, Turkemen and Straight Egyptians.

“The Arabian horse has a special mystique due to the long-recorded history of the breed,” Brooks said. “Arabian horse breeders, in particular, know their horse’s bloodlines many generations back. What we found was that in the area where this breed originates – likely the near East region, but we don’t know exactly – there’s a healthy level of diversity. This is particularly evident in populations from Bahrain and Syria, which suggests these are some pretty old populations.”

The Arabian is prized for characteristics like heat tolerance and endurance, as well as its unique appearance, with a dish-shaped facial profile, wide-set eyes, an arched neck and a high tail carriage. It has been exported from its ancestral homeland for centuries, with some modern lineages drawn strictly from these smaller genetic pools, giving the breed a reputation for inbred disorders. While this was true for some groups they tested, Brooks noted, they also found remarkable diversity when considering the breed as a whole.

Brooks contrasted the discovery of more diverse populations with the samples they received from racing Arabians. Another longstanding myth says that the Arabian contributed genetically to the modern Thoroughbred, but the racing Arabians’ DNA told a different story. The research team found little influence of the Arabian in the modern Thoroughbred’s DNA

“What we found in these samples was not that much Arabian ancestry was part of the Thoroughbred line, but the opposite: that Thoroughbred DNA exists in most of the modern racing Arabian lines, indicating a more recent interbreeding within this group,” Brooks said. “I can’t speculate on the how or why, but this is clearly the story the DNA is telling us.”

Another implication of this study, Brooks said, is the potential to identify the genetic regions that determine some of the Arabian’s unique traits, like their facial profile. This could be expanded to identify the marker for other horse breeds’ head shapes, for example.

The study has a long list of co-authors, with contributors from the University of Tehran, Iran; Weill Cornell Medical College in Qatar; the University of Kentucky; the University of Agriculture in Kraków, Poland; the Hong Kong Jockey Club; the Equine Veterinary Medical Center in Doha, Qatar; and the University of Veterinary Medicine Vienna, Austria. Elissa Cosgrove from the Clark lab and Raheleh Sadeghi, a visiting scientist from Iran in the Antczak lab, shared first co-authorship of the study.

“An exceptional aspect of this project was the wonderful level of open collaboration and sharing of resources by veterinary geneticists, equine scientists, and horsemen from around the world,” Antczak said. “It was a great pleasure to conduct this global study for the benefit of the horse.”

For more details, see:

Genome Diversity and the Origin of the Arabian Horse

Elissa J. Cosgrove, Raheleh Sadeghi, Florencia Schlamp, Heather M. Holl, Mohammad Moradi-Shahrbabak, Seyed Reza Miraei-Ashtiani, Salma Abdalla, Ben Shykind, Mats Troedsson, Monika Stefaniuk-Szmukier, Anil Prabhu, Stefania Bucca, Monika Bugno-Poniewierska, Barbara Wallner, Joel Malek, Donald C. Miller, Andrew G. Clark, Douglas F. Antczak & Samantha A. Brooks

Scientific Reports (2020) vol 10, Article number: 9702 (2020)

https://doi.org/10.1038/s41598-020-66232-1