Equine disease alerts remind owners to be vigilant about vaccinations 

According to the Equine Disease Communication Center website, equinediseasecc.org/alerts, there are numerous diseases for horse owners to be aware of and have proper vaccinations for their animals.  

Equine Herpesvirus-Respiratory

One case was reported Aug. 9 in McIntosh County, North Dakota. One equine at a private facility was diagnosed and confirmed by the state veterinarian. No quarantine was issued. 

Equine herpesvirus is a family of equine viruses named by numbers including EHV-1, 2, 3, 4 and 5 with EHV-1,3,4 posing the most risk for domestic horses. EHV is a common DNA virus that occurs in horse populations worldwide. The two most common species are EHV-1 and EHV-4 and most often cause a respiratory disease, which is usually mild and self-limiting, and both can cause abortion. 

EHV-1 and EHV-4 (very rare) can cause the neurologic form of the disease (equine herpesvirus myeloencephalopathy (EHM)), which creates damage to the spinal cord and can be fatal. EHV-3 causes coital exanthema, a venereal disease which affects the external genitalia. Horses can be carriers of EHV with no clinical signs and can spread the disease to other horses. Testing and quarantining affected horses in isolation is the primary way to control the disease. Vaccines are available but do not completely prevent any form of the disease. 

Equine Infectious Anemia

On Sept. 4, it was announced a quarter horse in Montague County, Texas, and another in Midland County, had been confirmed with EIA by Texas Animal Health Commission. Both horses have been euthanized. The premises was quarantined and will not be released until TAHC’s requirements are met. TAHC staff are working closely with the owners and local veterinarians to monitor potentially exposed horses and implement biosecurity measures. 

On Aug. 9, in Dona Ana County, New Mexico, four racehorses were identified and quarantined on suspicion of EIA. The horses ranged in age from 2 to 9 and were primarily used for racing. Testing of additional horses is being scheduled. 

On July 18, Texas Animal Health Commission officials confirmed equine infectious anemia in a quarter horse on a Hunt County, Ellis County and El Paso County premises. The horses were ultimately euthanized. The premises have been quarantined and will not be released until TAHC’s requirements are met. TAHC staff are working closely with the owners and local veterinarians to monitor potentially exposed horses and implement biosecurity measures. 

The Nebraska Department of Agriculture confirmed a case of equine infectious anemia in a horse in Colfax County on July 5. This was the first confirmed case of EIA in Nebraska since 2013. The horses on the infected premises have been quarantined and will be released after state regulations are met. NDA staff are working with the owner and local veterinarian to monitor potentially exposed horses. 

On June 24, TAHC officials identified a horse in Starr County, Texas, with EIA. Ultimately this horse was euthanized. 

Equine infectious anemia is a potentially fatal blood-borne infectious viral disease that produces a persistent infection among equids nearly worldwide. 

EIA is diagnosed by testing antibody levels in the blood. The most common test used to diagnose EIA is called a Coggins test. Antibodies are detected by two tests, AGID (agar gel immunodiffusion) and ELISA. Both tests are available in many laboratories; the ELISA requires less time for to receive results. 

There is no treatment or cure for EIA and horses confirmed positive can be quarantined for the rest of their life but are usually euthanized. Horses can be subclinical carriers as they can shed the virus for the duration of their lifetime and are usually euthanized, if confirmed positive, for the disease. 

West Nile virus

On Aug. 30, a horse in Cooke County, Texas, was confirmed to have WNV. The yearling quarter horse filly exhibited signs including hyperesthesia, muzzle tremors, mild ataxia. The filly was unvaccinated.  

On Aug. 30, a horse in Weld County, Colorado, was confirmed by the state veterinarian to have WNV. The 8-year-old quarter horse gelding was used for racing and was unvaccinated.  

In Missouri, a Boone County horse was confirmed to have WNV on Aug. 23. The 16-year-old Arabian started showing signs on Aug. 12, with a seven-day history of neurologic abnormalities and ataxia. Upon presentation, the mare had a head tilt and vestibular abnormalities. She developed muscle fasciculations and became weak and laterally recumbent while hospitalized but remained afebrile. The weakness progressed and humane euthanasia was elected. The horse was vaccinated. 

Another horse was identified Aug. 22 in Larimer County, Colorado, to have WNV. The 3-year-old mare was vaccinated and showing signs including: ataxia hyperesthesia or inability to stand without help. The horse is recovering. Another horse in Larimer County was also confirmed Aug. 22. The 5-year-old gelding was unvaccinated but is recovering.  

Oklahoma state veterinarian confirmed one case of WNV at a private facility in Latimer County, Aug. 22. The 2-year-old filly was unvaccinated and showed signs of disease including depression, fever and mild stumbling. The horse has since recovered. No quarantine was issued. 

A horse in Pueblo County, Colorado was confirmed Aug. 19 to have WNV. The 2-year-old filly was showing ataxia, anorexia, abnormal mentation, unable to rise, and cranial nerve deficits. The horse was unvaccinated and ultimately euthanized. 

Another horse in McCurtain County, Oklahoma, was confirmed with WNV on Aug. 8. It too was unvaccinated, and had signs of stumbling, depression and blindness. The horse was born and raised in Oklahoma; however, had recently been at a training facility in Texas and had been back in the state for a week before showing clinical signs. The horse has since recovered.  

A horse in Harper County, Oklahoma, was confirmed with WNV July 25. The 3-year-old gelding had incoordination or ataxia on all four limbs. The horse was unvaccinated but has since recovered.  

West Nile virus is a mosquito-borne flavivirus. WNV primarily causes disease in birds, humans, and horses and is transmitted by many different species of mosquitoes. Since 1999, more than 27,600 U.S. horses have been confirmed with WNV neuro-invasive disease with an estimated average case fatality rate of 30 to 40%. There is no cure for the virus. 

Supportive care is administered to horses with clinical signs. To help prevent WNV, keep all horses up to date on vaccinations. Initial vaccination is followed in four to six weeks with a booster; yearly revaccination is recommended after. More frequent boosters (i.e. twice yearly) are recommended in areas with year-round mosquito seasons and in endemic areas. Practice vector management on all properties where horses are kept. 

Eastern Equine Encephalitis

Texas Animal Health Commission confirmed a case of EEE on Aug. 26, near Houston, Texas, in two horses. No quarantine was issued.  

On Aug. 2, a horse with EEE was confirmed by the Arkansas Department of Agriculture. No other horses were exposed to the infected horse. No quarantine was issued. 

Eastern Equine Encephalitis also known as sleeping sickness, is a viral disease that causes inflammation of the brain and spinal cord. It is transmitted by mosquitoes. There is no cure for EEE. Supportive care is administered in horses that show clinical signs. Vaccination for EEE is highly effective and is recommended as a core vaccination. 

More information about the diseases, alerts and outbreaks can be found at equinediseasecc.org/. 

Kylene Scott can be reached at 620-227-1804 or [email protected].