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NZ Horse Diagnosed With Novel Papilloma Virus

A 10-year-old Warmblood gelding in New Zealand was referred to a veterinary clinic with two masses on his left fetlock. The masses were each over an inch in diameter and had hard, rough surfaces. They grew rapidly in the three weeks since the horse's owner had discovered them. A piece of one of the masses was sent for microscopic evaluation and Drs. John Munday, Michael Hardcastle and Melissa Sim determined that a novel papillomavirus caused the lesions.

Papillomaviruses are double-stranded DNA viruses that tend to be host specific. There are nine equine papillomaviruses that have been sequenced; the first to be sequenced was Equus caballus type 1 (EcPV1), which causes papillomas in horses.

The masses the gelding had were most similar to EcPV1, but they didn't present in the same way: EcPV1 generally causes small masses around the face. Veterinarians treated the masses with imiquimod ad the lesions resolved in 14 weeks.

The study team noted that papillomas only develop when a host is infected by a papillomavirus for the first time, which is why warts (papillomas) typically develop in young horses. This is an additional indication that the virus that caused the lesions in the older horse is new.

Read the full study here.

Research Shows Horses More Susceptible To COVID-19 Than Other Species

New research shows that horses seem to be at greater risk of contracting COVID-19 than other species. Researchers believe their close relationship with humans may be to blame for a greater susceptibility.

Vanderbilt University utilized experts in virology, genetics, structural biology, chemistry, physiology, medicine, immunology and pharmacology worked together to create a tool that would predict animal susceptibility to COVID-19 infection. The scientists determined that horses and camels were most at risk and suggested that they be closely monitored and tested for infection.

The researchers identified five amino acid sites that indicate virus susceptibility or resistance; they then created an algorithm to predict susceptibility. Jacquelyn Brown, a staff scientist at the Vanderbilt Institute for Integrative Biosystems Research and Education, is an equestrian who initiated the project, noting that horses have a large respiratory system, and many are regularly have their mouths and nostrils touched by humans.

The research team is hopeful that their findings will help protect pets, food sources, wildlife and people. The algorithm the team created can be modified to predict susceptibility to other viruses; there is also hope that the research will be used to help develop drugs to inhibit virus transmission.

Drs. Matthew Alexander, Clara Schoeder, Jacquelyn Brown, Charles Smart, Chris Moth, John Wikswo, John Capra, Jens Meiler, Wenbiao Chen and Meena Madhur determined that there as an intermediate risk for COVID-19 susceptibility in cows, sheep and goats; the most susceptible animal is the rhesus macaque.

Read the full study here.

African Horse Sickness Outbreak In Malaysia

Five horses in Malaysia have been diagnosed with African Horse Sickness; the disease had never been confirmed in the country until this outbreak. The horses lived in Terengganu, located in the eastern part of the Malay Peninsula. On September 2, Malay authorities reported the outbreak, noting that the horses had been exhibiting signs of the disease since early August. The horses had difficulty breathing, were lame and had a fever.

The source of the virus is not known. There are nine different serotypes of African Horse Sickness, each with a specific geographic distribution. Identifying the serotype may indicate from which region the virus originated. AHS is transmitted by biting midges and the disease tends to be seasonal; it's generally associated with hot and humid weather.

The Malaysian outbreak follows on the heels of an AHS outbreak in Thailand, where 604 horses were affected and 562 died. Malaysia is approximately 550 miles from Thailand, but it is unknown if the occurrence in Malaysia is the from the movement of horses, the movement of infected vectors or is a new occurrence of the disease.

AHS affects all species of Equidae and the severity of clinical signs is dependent upon the virus strain and species affected. The fatality rate in horses can reach up to 90 percent. Though there is a commercial vaccine for AHS, none are approved for use in the European Union.

Virus Believed To Cause Equine Liver Disease Found To Be Innocuous

Theiler's disease, which has been recognized in horses for the last 100 years, has long been believed to cause transmissible hepatitis, though the pathogen that causes it has never been identified. New research shows that the virus originally blamed for causing liver disease doesn't appear to be the cause at all–and that the suspected virus is virtually harmless.

Researchers discovered two novel equine pegiviruses (EPgV); EPgV-1 was not associated with disease and the other was identified as the cause of an outbreak of serum hepatitis in horses. That specific EPgV was dubbed Theiler's disease-associated virus (TDAV).

Drs. Joy Tomlinson ,Raphael Wolfisberg, Ulrik Fahnøe, Himanshu Sharma, Randall Renshaw, Louise Nielsen, Eiko Nishiuchi, Christina Holm, Edward Dubovi, Brad Rosenberg, Bud Tennant, Jens Bukh,Amit Kapoor,Thomas Divers, Charles Rice, Gerlinde Van de Walle, Troels Scheel used more than 20 types of tissue from horses being screened for the viruses to learn more about EPgV-1.

They found high viral loads in bone marrow, serum and the spleen; some lymph nodes and blood cells were positive, but liver tissue was not. The researchers concluded that the equine pegiviruses cause infections in horses, but not hepatitis. Bone marrow was identified as the primary site of replication for both viruses.

The researchers also noted that a newly discovered parvovirus seems to be responsible for multiple equine Theiler's disease cases.