IBR

This disease occurs worldwide, including New Zealand. Studies have shown that IBR infections in adult dairy cows are very common, approximately 60-80% of dairy farms in New Zealand having the virus within them. Outbreaks commonly occur in heifers and IBR is more common in dairy herds, rather than beef cattle. This is to do with dairy cattle being in closer proximity to each other and entering the same shed, once or twice a day.  Once a cow has been infected with this disease, it may remain with them lifelong, remaining ‘dormant’ until the cow is put under pressure or stressed.

In New Zealand, most cows infected with IBR, do not show any signs. In more severe cases you may see nasal and eye discharge, coughing, loss of appetite and a drop of milk production. This disease can also affect the vaginal mucosa, which can cause swelling and pus-filled lesions. Cattle with these lesions may seem uncomfortable especially during urination and may have a reduced willingness to be mated. This would affect their fertility for several weeks until the lesions have healed.

IBR is transmitted (for respiratory signs) from cow to cow via coughing and discharges or with contact with surfaces contaminated with the virus. IBR is a very hardy virus and survives for extended periods on surfaces.

IBR will also affect bulls, causing temporary infertility and infected bulls will transmit IBR either by direct contact, or via infected semen during mating.

If you suspect clinical signs of IBR, it is best to talk to our vets. Depending on the signs displayed by your cows, we may take nasal swabs, and a series of blood samples. Other conditions, such as nasal catarrh, pink eye, facial eczema, and lung worm may display similar symptoms to IBR and that is why we are happy to provide advice.

There are other strains of IBR that occur overseas that we do not have here. These strains cause abortions, calf ill thrift and neurological signs.

IBR is also a significant disease for overseas live export markets. While the days may be numbered for live cattle exports, IBR is one of the diseases screened for by many export countries. Control of the disease is therefore essential within animals which are likely destined for live export to avoid hurdles and stock rejection. Discussion with your vet regarding mitigating IBR within export cattle is therefore essential.

How can you control the disease?

• Maintain a closed herd and isolate and test any cows that you may think are showing signs.
• Swab or blood testing of new stock brought onto farm, especially breeding bulls.
• Vaccination of bulls pre-mating.
• Vaccinate herd can be carried out on high challenge farms.
• Good hygiene, hosing down and disinfection of cow shed and bars.

If you are concerned about IBR being present within or being introduced to your herd, contact one of our veterinarians to discuss how to go about defining the status of your herd further. Testing can also be built into an existing biosecurity plan on farm to minimise the impact of possible ill health effects within your herd.