Horse News & Views - March 2005

Ministry of Agriculture, Food and Rural Affairs

Ontario Association of Equine Practitioners

• Horses should never be fed or exposed to cattle or poultry feeds since these feeds may contain ionophores (monensin, lasalocid). The LD 50 (lethal dose where 50% will die) of ionophores for horses is low (1-2 mg/kg). Horse poisonings have occurred when horses consumed chicken feed containing 99 mg/kg of an ionophore, or cattle feed/cattle mineral, which may contain 2,500 mg/kg of an ionophore. Signs in horses include: lethargy, cyanosis, depression, pulmonary edema, liver failure, heart failure and death.

• Due to the recent outbreak of equine viral rhinopneumonitis (equine herpesvirus) at a racetrack in Michigan, the Ontario Racing Commission is implementing new procedures, effective immediately. All horses coming to Ontario from another jurisdiction must be examined by the Commission/Official Veterinarian prior to being allowed entry into the paddock or ship-in barn area at any Ontario racetrack. The examination will include, but may not be limited to, taking the horse's temperature. For further information, contact Dr. Bruce Duncan, Ontario Racing Commission, Tel. (416) 327-0520.

• Respiratory virus outbreaks are common among horses that are assembled for events, such as racing, showing and horse auctions. In many of these outbreaks, the clinical signs are not characteristic of a specific virus and confirmation requires laboratory testing. Any one of several viruses may be isolated: equine influenza virus type A subtype 1 (AE-1; H7N7) or subtype 2 (AE-2; H3N8); equine herpesvirus type 1 (EHV-1) or type 4 (EHV- 4); equine rhinovirus type 1 (ERV-1) or type 2 (ERV-2); equine arteritis virus (EAV) and equine adenovirus.

Related Links

• Preventing Disease Spread - Personal Hygiene and Disinfectants around Horse Barns
  
• Biosecurity for Horse Farms

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