Disease Alerts

Number Confirmed: 1; 
Number Exposed: 3; 
Facility Type: Boarding Facility; 

Horse 1: 
Age: 14; Gender: Mare; Breed: Thoroughbred (TB); Onset of Clinical Signs: 3/31/2026; Clinical Signs: This mare was found down in the field on Mar 31. She was assisted into the barn and then into isolation where she became recumbent with urinary incontinence. Her condition worsened and she was euthanized April 1. Blood and nasal swab samples were positive for EHV-1 by PCR.; Horse Status: Euthanized; 

Comments: The facility owner, working with their veterinarian, has instituted voluntary animal movement restrictions and biosecurity protocols. To see past and present EHV-1 neurologic (EHM) cases in Ontario go to: https://www.oahn.ca/resources/ontario-equine-disease-alerts/ and enter the disease surveillance portal;

Number Confirmed: 1; 
Number Suspected: 1; 
Number Exposed: 40; 
Number Euthanized: 1; 
Facility Type: Boarding Facility; 
Comments: A veterinarian contacted my office to report a geriatric horse with neurological signs at a 40+ horse boarding facility. There are multiple owners and multiple veterinarians have patients there. This horse was euthanized and sent for cremation so no testing was conducted. She then reported a second horse with milder signs. No other horses at the farm are clinically affected. Both affected horses shared the same paddock but there are multiple paddocks. Horses otherwise of sharing a paddock have limited access to each other. The second horse was tested for EHV-1 by PCR and was confirmed to be positive. The farm owner is not aware of any horses recently leaving or coming to the farm, but by her admission, she may not have known if there was any movement of horses. She said most of the horses there have been there for years and don't leave the premises. Upon receiving lab confirmation a state quarantine was issued. The horse that was tested had mild neurological signs and those signs resolved with supportive treatment.;

Number Confirmed: 10; 
Number Exposed: 25; 
Number Euthanized: 1; 
Facility Type: Private Facility; 
Comments: Quarantine was released on March 21.; 
Previous Alerts: 4905, 4904

Number Confirmed: 1; 
Number Exposed: 3; 
Number Euthanized: 1; 
Comments: No additional case were confirmed during the quarantine monitoring period. The quarantine period has been fully completed and is officially released.; 
Previous Alerts: 4898

Number Confirmed: 1; 
Number Suspected: 1; 
Number Exposed: 29; 
Number Euthanized: 1; 
Facility Type: Boarding Facility; 

Horse 1: 
Age: 19; Gender: Gelding; Breed: Thoroughbred (TB); Usage: Pleasure Riding; Onset of Clinical Signs: 3/7/2026; Confirmation Date: 3/9/2026; Horse Status: Quarantined; Vaccination Status: Unvaccinated;

Number Confirmed: 1; 
Number Suspected: 3; 
Number Exposed: 38; 
Number Euthanized: 1; 
Comments: Quarantine released, no further neurologic cases detected after index case.;

Previous Alert: 4852

Number Confirmed: 10; 
Number Exposed: 25; 
Number Euthanized: 1; 
Comments: Quarantine is still in effect for the premises.; 
Previous Alerts: 4904

Number Confirmed: 2; 
Number Euthanized: 1; 
Comments: Case was originally posted Feb. 24, 2026;

Number Confirmed: 1; 
Number Exposed: 3; 
Number Euthanized: 1; 

Horse 1: 
Age: 16; Gender: Gelding; Breed: Tennessee Walking Horses; Clinical Signs: ataxia, trouble urinating, recumbent; Confirmation Date: 3/2/2026; Horse Status: Euthanized; 

Comments: A 16-year-old Tennessee Walker gelding from Santa Barbara County displaying neurologic signs was confirmed positive for Equine Herpesvirus Myeloencephalopathy (EHM) secondary to Equine Herpesvirus-1 (EHV-1). The gelding was euthanized due to severity of clinical signs. Three (3) potentially exposed horses at the home premises in Santa Barbara County were quarantined with enhanced biosecurity measures implemented. There has been no history of horses on or off the property in more than 30 days. CDFA has been onsite and will continue to actively monitor the situation.;

Number Confirmed: 1; 
Number Exposed: 11; 
Facility Type: Private Facility; 

Horse 1: 
Age: 5; Gender: Gelding; Breed: Standardbred; Usage: Pleasure Riding; Clinical Signs: Neurologic, ataxic; Confirmation Date: 2/25/2026; Horse Status: Recovering; Vaccination Status: Unvaccinated;