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A research protocol was designed to eradicate the virus in pigs sourced from a PRCV positive sow herd. The sow herd is a 150 farrow to finish herd, under one roof, and is PRRS and Mycoplasma hyopneumoniae negative. Forty piglets were weaned from nursing gilts/sows at 5 days of age and removed to a separate nursery which had been thoroughly disinfected and cleaned.
Piglets were treated with tulathromycin at label dose at weaning and again with Ceftiofur Crystalline Free Acid at label dose one week later. CTC/Tiamulin (1 kg/1.75 kg/tonne) was included in the first two weaning rations. Piglets were blood tested on entry and at intervals of one month for a total of 4 tests. Nasal swabs were taken on entry and again at the end of the study, when piglets were approximately 3 months of age.
Initial swabbing revealed that none of the piglets were PCR positive on nasal swabs for porcine respiratory coronavirus. 12 of 40 piglets were initially antibody positive on the July test (the first bleeding). These were assumed to be maternal titres. Of these 12, 4 remained positive in August on the second bleed, and by the third bleed all piglets were negative and remained so for the fourth bleeding in October. The final nasal swabbing in October showed that none of the piglets were positive for virus. A second trial is scheduled to begin in March of 2011.
Medicated early weaning of piglets at 5 days of age was successful in avoiding exposure of the piglets to PRCV virus. This implies that the virus was circulating at a later stage of production in the home barn; however, this project was not designed to determine where the virus was circulating. 12 piglets were positive on blocking ELISA for PRCV; this implied that their dams had been exposed and that antibody had been transferred to the piglet via colostral intake. During the first two months of the study, the maternal antibodies declined sufficiently that they were no longer detectable by blocking ELISA. The lack of seroconversion to positive status confirmed that the piglets were not exposed to live virus after the transfer to the nursery.
This technique demonstrates that it is possible to eliminate PRCV from swine using a segregated early weaning technique. However, it would be prudent to determine where the virus is circulating in a swine facility prior to attempting to eradicate the virus, as transferring piglets to a nursery after they have already been exposed to virus would require an extended period of time (up to one year) in the isolation barn in order to become seronegative.
Piglets were treated with tulathromycin at label dose at weaning and again with Ceftiofur Crystalline Free Acid at label dose one week later. CTC/Tiamulin (1 kg/1.75 kg/tonne) was included in the first two weaning rations. Piglets were blood tested on entry and at intervals of one month for a total of 4 tests. Nasal swabs were taken on entry and again at the end of the study, when piglets were approximately 3 months of age.
Initial swabbing revealed that none of the piglets were PCR positive on nasal swabs for porcine respiratory coronavirus. 12 of 40 piglets were initially antibody positive on the July test (the first bleeding). These were assumed to be maternal titres. Of these 12, 4 remained positive in August on the second bleed, and by the third bleed all piglets were negative and remained so for the fourth bleeding in October. The final nasal swabbing in October showed that none of the piglets were positive for virus. A second trial is scheduled to begin in March of 2011.
Medicated early weaning of piglets at 5 days of age was successful in avoiding exposure of the piglets to PRCV virus. This implies that the virus was circulating at a later stage of production in the home barn; however, this project was not designed to determine where the virus was circulating. 12 piglets were positive on blocking ELISA for PRCV; this implied that their dams had been exposed and that antibody had been transferred to the piglet via colostral intake. During the first two months of the study, the maternal antibodies declined sufficiently that they were no longer detectable by blocking ELISA. The lack of seroconversion to positive status confirmed that the piglets were not exposed to live virus after the transfer to the nursery.
This technique demonstrates that it is possible to eliminate PRCV from swine using a segregated early weaning technique. However, it would be prudent to determine where the virus is circulating in a swine facility prior to attempting to eradicate the virus, as transferring piglets to a nursery after they have already been exposed to virus would require an extended period of time (up to one year) in the isolation barn in order to become seronegative.
S. Burlatschenko and C. Arsenault. Elimination of Porcine Respiratory Coronavirus. 30th Centralia Swine Research Update, Kirkton Ontario 26 January 2011.
