An outbreak of Neurotropic Equine Herpes Virus-1 has spread from the United States to Canada.
Horses became infected at a cutting horse event in Utah held from late April to early May. Cases have arisen across the northwestern United States and in British Columbia and Alberta.
B.C. has seen three cases and Alberta has one confirmed case of the neurological strain of the disease. In all cases, the infected horses have been isolated and are responding to treatment. Two horses in Idaho have died.
According to Dr. Chris Clark of the Western College of Veterinary Medicine in Saskatoon, the respiratory form of Equine Herpes Virus is common in horses. About 80 percent of horses carry the disease.
Infection often occurs within the first few years of a horse’s life. A portion of the virus lies dormant in nerve cells after symptoms subside and the disease can then break out if animals become stressed or if their immune systems become compromised. This type of recurrence is similar to the virus that causes cold sores in humans.
In rare cases, as has happened with the recent outbreak, the virus spreads from the respiratory system into the blood stream, eventually collecting in the spine and causing the more severe neurological variant of the disease.
Clark echoed advice delivered in letters to veterinarians and horse owners by Alberta’s chief provincial veterinarian, urging horse owners to remain vigilant and practice good bio-security.
Various cutting horse events have been cancelled as a precautionary measure. Clark maintains that overall, the situation appears to be well contained. He encouraged concerned horse owners to consult their veterinarians to determine what, if any, extra measures might be necessary.
Clark stressed that EHV-1 cannot be transmitted to humans.
