Four out of five dairy herds in Mayo could be positive for the highly infectious viral disease infectious bovine rhinotracheitis, according to the results of a survey carried out by leading veterinary practitioner Pat Kirwan.
The survey, which involved blood tests and bulk milk tests, was carried out last spring on a representative sample of 70 herds in the northeast. The results showed that 80 per cent of unvaccinated herds are positive to IBR. A classic symptom is sudden milk drop, and surveys have shown milk yield reductions of more than 170 litres in cows suffering from the disease.
The clinical signs include raised temperature, coughing, and conjunctivitis. Infected cows are prone to abortion in the second half of pregnancy and can suffer from poor fertility.
While over 20 per cent of the herds in Pat Kirwan’s survey were vaccinated against IBR, the level of vaccination in the national dairy herd is less than 10 per cent, according to Fergal Morris, veterinary adviser with Intervet/Schering Plough. Where an outbreak of IBR is suspected, he urged famers to seek immediate veterinary advice and to vaccinate against the disease.
Pat Kirwan said using a marker vaccine has the advantage of distinguishing between animals who are infected with IBR and those who are vaccinated. He said the best control of IBR will be got through bi-annual vaccination of the entire herd.