Animal Health Focus JULY 2018 IBRandAI Bulls William Fitzgerald, Member of the IBR Technical Working Group, Animal Health Ireland. Infectious Bovine Rhinotracheitis (IBR) is caused by a bovine herpes virus, specifically BoHV-1, though more commonly it is known as IBR virus. As IBR virus is a herpes virus, it shares many of the herpesvirus characteristics, specifically its ability to become latent or hidden following infection. Research has shown that, most animals, once initially infected, recover but do not eliminate the virus. Instead, the virus enters a sleeping state, most commonly in the brain, and is not re-awakened until episodes of stress occur. Stress can have many causes but some of the more common ones include transport, calving, nutritional stress or mixing of animals. This re-activated source of infection leads to further spreading of the virus and, in turn, more animals will become carriers of the disease. Most commonly, IBR virus causes respiratory disease particularly affecting the nose and upper airways of cattle. The windpipe is commonly affected and the tissues lining it are commonly destroyed during infection. Animals experiencing IBR usually present with fever, dullness, a clear discharge from the nose (which can become yellow when a secondary bacterial infection develops), rapid breathing, and milk drop in dairy cows. IBR virus is very contagious. After the initial infection occurs by inhaling the virus, facilitated by close contact, a susceptible animal can shed high levels of virus in fluid from their eyes, nose and mouth for anything up to 14 days. It is worth noting that in 2016 IBR was detected in 12 per cent of all bovine carcases over 12 months of age presented to the Regional Veterinary Laboratory network where respiratory disease was recorded as the cause of death. IBR virus can cause abortion in pregnant animals and most commonly causes abortion from four months onwards. Occasionally, IBR virus can infect calves at a very young age, typically 2-3 days old and can cause a systemic viral infection which allows the virus to a ack vital organs like the liver and often leads to the death of the calf. IBR virus can also be shed by semen and genital contact. Genital infection by IBR virus causes a lesser known illness, infectious balanoposthitis (IBPV, in bulls) and pustular vulvovaginitis (IPVV, in cows), whereby infection leads to blister-like lesions on the penis or the lining of the vulva and vagina. This can lead to a temporary loss of Due to its many manifestations, it is imperative to control this highly infectious virus, which can be achieved by a mixture of vaccination and biosecurity. 34 fertility in bulls and endometritis in cows. Outbreaks of IPVV have been recorded around the world where frozen semen containing the virus was implicated as the cause. For all of these reasons, IBR is seen as a disease with serious consequences. As a result, the entry of bulls that have evidence of exposure to IBR virus (including as a result of vaccination) to AI centres is prohibited. A number of European countries have either eradicated IBR or have embarked on programmes to eradicate it. Due to its many manifestations and as many of the animals affected by respiratory IBR succumb to secondary bacterial infections, it is imperative to control this highly infectious virus. This can be achieved by a mixture of vaccination and biosecurity. Both inactivated and modified live (marker) vaccines are available in Ireland. This was originally printed in the Animal Health Ireland’s Bulletin