Swine breeders who have herds that test positive for Porcine Respiratory Coronavirus (PRCV) may now be able to access live genetic exports markets that have been inaccessible, through segregated early weaning and stringent biosecurity protocols. “We decided to do this research project because interested Ontario swine breeders are missing out on some export opportunities,” says Dr. Sue Burlatschenko of Goshen Ridge Veterinary Services. The Tillsonburg, Ontario-based vet established the protocol at the encouragement of
Donaldson International Inc., a Canadian swine genetics exporting company. Burlatschenko’s study builds on an earlier PRCV pilot project carried out by Donaldson and Dr. Christa Arsenault of Tavistock Veterinarians.
“Some countries claim to be free of PRCV and require imported animals to test negative for the virus. This can be a difficult requirement for high-health Ontario herds that wish to export swine, buttest positive for PRCV antibodies,” she says. Her eradication protocol will make it easier for producers to manage the export limitations posed by the widespread virus.
Understanding PRCV
“Probably 90% or more Ontario herds are positive for it. But it’s really not a bad thing to be positive for,” says Burlatschenko, explaining that it is related but distinct from Transmissible
Gastro-Enteritis (TGE) virus, which causes vomiting and diarrhea symptoms to spread rapidly through a herd. In contrast, PRCV infections are usually not visible, rarely cause production
losses and confer cross-protection against TGE infection. Most pigs are infected after weaning as maternal antibodies (immunity passed from sow to piglet) decline. PRCV is transmitted by pig-to-pig contact or by airborne transmission. The virus is believed to travel some distance and, because of this, it is extremely difficult to keep herds free from it.
Successful eradication
Burlatschenko designed the eradication protocol using pigs sourced from a farrow-to-finish operation infected with PRCV. Forty piglets were weaned from nursing gilts/sows at five days of age and moved to an off-site nursery, which had been thoroughly disinfected and cleaned.
Because the piglets were weaned much earlier than normal, they were fed a special diet of milk and high-quality feed to get them off to a proper start.Piglets were blood tested on entry and at intervals of one month for a total of four tests. Nasal swabs were taken on entry and again at the end of the study when piglets were approximately three months old. A number of piglets demonstrated maternal antibodies, which declined rapidly during the course of the study.
“At the completion, all pigs were negative via blood test and nasal swab for PRCV indicating our eradication was successful,” says Burlatschenko, who replicated the study a few months later
Source: OntarioPork