outbreak | Horse Racing Free Tips

AAEP Publishes Contagious Equine Metritis Guidelines

Comprehensive guidelines to assist veterinarians with identification, diagnosis and control of Contagious Equine Metritis (CEM), a non-systemic venereal disease of equines that causes short-term infertility in mares and rare abortion, are now available on the AAEP's website.

Six outbreaks of CEM have occurred in the U.S. in the past 15 years, including a significant outbreak in 2008 to 2010 in which over 1,000 exposed horses in 48 states were required to be tested, resulting in 23 contaminated stallions and five infected mares ultimately identified and treated.

“Outbreaks in the U.S. have demonstrated the risk of incursions and the need for surveillance in the active breeding population to identify cases early and limit disease spread,” said guidelines co-author Dr. Abby Sage, Richmond staff veterinarian for the Virginia Department of Agriculture and Consumer Services. “Several of these outbreaks also demonstrated significant stallion-to-stallion spread of Taylor equigenitalis via fomites and inadequate biosecurity during semen collection and stallion handling.”

Dr. Sage and co-author Dr. Peter Timoney, the Frederick Van Lennep Chair in Equine Veterinary Science at the University of Kentucky's Gluck Equine Research Center, advise equine practitioners and stallion owners/managers to follow stringent biosecurity protocols when collecting and handling stallions and consider implementation of annual testing of active breeding stallions prior to breeding season as ongoing assurance of disease freedom.

CEM is an internationally reportable disease. When the carrier status of a stallion or infection of a mare is suspected, practitioners should contact their state and/or federal animal health official, who will provide current collection and response procedures for suspect cases.

[Story Continues Below]

The CEM Guidelines were reviewed and approved by the AAEP's Infectious Disease Committee and board of directors. View the guidelines or save them to your mobile device for future reference here.

Besides CEM, AAEP guidelines for 22 additional equine infectious diseases are available here.

Study: Thailand’s African Horse Sickness Outbreak Likely Started From Just One Animal

Scientists have found that the 2020 outbreak of African Horse Sickness in Thailand most likely came from just one affected animal entering the country. Hundreds of horses were killed in the country's first outbreak of the disease, which is spread by biting midges.

Dr. Napawan Bunpapong and a research team from Chulalongkorn University in Bangkok used molecular-based testing to help determine the disease's origin. They discovered that every blood and tissue sample taken from affected horses in Thailand contained the virus, and more specifically, contained unique amino acids, indicating a single, common origin. The researchers suggest that the virus may have come from an asymptomatic animal like a zebra.

[Story Continues Below]

The government of Thailand restricted movement and enforced quarantine, disinfection and vector control to try to staunch the spread of the disease. Mass vaccination was also completed in Thailand and neighboring countries.

Affected horses had a fever and swelling near their eyes; they became depressed and short of breath before dying suddenly within 48 hours.

Further Analysis Of March EHV-1 Outbreak Reveals New Variant Of The Disease

In March, eight horses housed at a Pennsylvania show barn were diagnosed with EHV-1 after having elevated temperatures but no other signs of illness. The cause of the outbreak has been found to be a new variant of the EHV-1 H752 genotype. The variant contains the same mutation as the EHV-1 outbreak in France.

EHV-1 can cause respiratory disease in young horses, early death in foals, abortions in mares and occasionally neurological disease. Neurologic issues are fairly uncommon, but can cause the death of the affected horse.

The 31 horses that lived at the affected barn were treated with valacyclovir, and ill horses also received flunixin meglumine and sodium heparin. The investigation team, led by Dr. Nicola Pusterla, believe that the early administration of valacyclovir may have prevented additional horses from falling ill with neurologic complications. Additionally, they note the lack of respiratory symptoms in these cases may be related to the recent administration of EHV vaccinations.

The distribution of the new genotype is not known.

Read the case report here.

Atypical Myopathy: Why Are Only Some Horses Affected?

Equine atypical myopathy is an unusual, deadly disease which is poorly-understood. If a group of horses is turned out together, only some will be affected by the debilitating disease, caused by the ingestion of the seeds or saplings of specific trees in the Acer family.

Equine atypical myopathy typically affects horses that live on pasture in the spring and fall. It has been seen in Europe since the mid-1990s. Some 2,500 cases have been reported in the last decade.

Researchers believe intestinal bacteria may play a role in why some horses get the disease while herdmates don't. Drs. Christina Wimmer-Scherr, Bernard Taminiau, Benoît Renaud, Gunther van Loon, Katrien Palmers, Dominique Votion, Hélène Amory, Georges Daube and Carla Cesarini hypothesized that fecal microbiota may play a role in whether or not horses became affected by the disease.

The study team used fecal samples from 59 horses with atypical myopathy that were referred to Belgian clinics: 29 horses that survived and 30 that didn't. The team also used 26 healthy horses that shared pastures with the affected horses during the outbreak periods.

The team concluded that horses suffering from atypical myopathy have different fecal microbiota than their healthy counterparts. The changes were more severe in horses that didn't survive the disease.

Horses impacted by atypical myopathy will suddenly become stiff and weak; they will have a rapid heart rate and dark urine. As the disease progresses, the horse may be unable to rise, experience breathing issues and eventually die. There is no cure and treatment of symptoms is often unsuccessful. The mortality rate is between 43 and 97 percent.

Read the article here.