IBR is caused by infection with bovine herpes virus type 1 and is highly prevalent in New Zealand cattle. Approximately 90% of local dairy herds will have been exposed to IBR and it is the most common reason for China export heifers being rejected.

IBR causes herpes virus lesions in the respiratory tract and/or the reproductive tract. Typical of herpes virus, once an animal is infected it is infected for life. Infected animals can shed the virus on multiple occasions, especially when the animal is under stress and the immune system is overwhelmed.

Clinical signs of IBR are usually associated with an upper respiratory tract viral infection:

• High fever.

• Runny eyes

• Nasal discharge. This is highly irritating, and animals will often rub their nose on sticks which can become stuck up the nose.

• Coughing.

• Difficulty breathing.

• Anorexia occurs, as a result the animals are lethargic and appear ill thrifty with reduced milk production.

IBR can also cause vesicles on the vulva and penis, neither of which is desirable during mating. IBR tends to be a problem in herds when naive heifers enter the herd and are exposed to the herpes virus for the first time.

Treatment

While there is no direct treatment to eliminate the viral infection. Infected animals should be isolated from the rest of the herd and treated with anti-inflammatories and antibiotics.

Prevention

Vaccine is available to prevent herpes virus infection in cattle and can be used in herds where IBR is problematic. It is especially useful to vaccinate naive heifers prior to entering the herd.