Infectious bovine rhinotracheitis (IBR) can be found in large parts of Europe. It is known to be a highly contagious and infectious disease. An infection of the upper respiratory tract, infectious bovine rhinotracheitis can cause large economic losses for cattle owners. Death is rarely an occurrence as a direct result of an IBR infection.
Infectious bovine rhinotracheitis is caused by a virus called the bovine herpes virus type 1 (BoHV-1) which, not unlike the human herpes virus, acts as a latent pathogen. The virus will rarely ever be fully eradicated from a cow’s system. Initially, upon entering the cow, the bovine herpes virus type 1 increases its numbers, multiplying in the respiratory tract. Next it travels via the blood into the cow’s foetus.
All unvaccinated cattle are susceptible to infectious bovine rhinotracheitis although calves can be more severely affected. This is because they have weaker immune systems than their older counterparts. Transmission can be a result of direct contact with infected animals or indirect contact with the contaminated surfaces. Care should be taken when moving from an area containing an infected cow to an area with unaffected cattle.
The signs and symptoms following infection include fever, nasal and ocular discharge. In some cases it can result in abortion and a decreased milk yield which contributes mainly to the reason for the economic losses on the farmer’s part. Calves can contract pneumonia as a secondary infection. It is usually in these cases of dual infections that the risk associated with fatalities become more likely. Vaccinations are available in different forms to prevent transfer or even to eradicate the disease.
Transmission of IBR
Transmission of infectious bovine rhinotracheitis can occur both directly and indirectly. Direct contact between infected cows and unaffected cows can generally result in the transfer of the bovine herpes virus type 1. As a latent virus, previously infected cows may shed the disease without showing any signs and therefore contribute to spreading it.
Stress can reactivate the disease. Infected bulls are able to transmit the virus via semen and so can infect many members of the herd in a short period of time. Additionally, humans are also able to act as a source of infection via contaminated clothes and footwear if they come into close proximity with an infected cow and then another cow. Embryonic transfer and sometimes aerosol droplets can also cause transmission.
Signs and symptoms of infectious bovine rhinotracheitis
As with most herpes viruses the bovine herpes virus type 1, which causes infectious bovine rhinotracheitis, results in latent infections. This means it remains in the cow and is shed by the animal when triggered by certain circumstances such as it experiencing stress. Signs and symptoms include possible abortions and a drop in fertility. There will be signs of fever, a loss of appetite, nasal and ocular discharge as well as increased breathing. Redness in the whites of the eyes and conjunctivitis are also a result of infection in some cows. Calves infected with the virus can become more susceptible to, and catch, pneumonia.
In more severe cases, a decrease in milk yield is observed which have economic consequences for dairy farmers. Cattle herds previously unaffected by the disease are prone to be more severely affected and a higher incidence of abortions and pneumonia is observed. Severity also increases if other secondary infections are contracted.
Treatment of infectious bovine rhinotracheitis
Unfortunately, there is no cure against infectious bovine rhinotracheitis and so mainly supportive therapy is used. For example, antibiotics are administered to prevent or treat secondary bacterial infections such as pneumonia. An anti-inflammatory is occasionally given for respiratory relief. Where many cows are infected, progressive culling is sometimes an option.
Prevention against IBR
Vaccinations are available against infectious bovine rhinotracheitis and many vaccines can be squirted up the nose rather than via injection. These forms are given to pregnant cows since the weakened vaccine can result in abortion. Calves are commonly administered the vaccine as early as three months old. Twice yearly or annual boosters are then required depending on the area to provide the cattle with long term immunity.
Calves vaccinated before the age of the three months for transport purposes are given their second dose two months after the first. Heifers should be vaccinated thirty to sixty days before introducing any impregnation techniques or introducing a bull. By fully vaccinating herds, farms and even whole countries can work towards eliminating the virus completely or at the very least, reducing its circulation.
If an animal is found to have the disease then, to prevent transfer, quarantine measures are put into place. Footbaths should be used if visitors are absolutely necessary, though ideally they should be prevented from entering, and vehicles should be restricted from entering the farm. Infected carcasses should be kept away from live cattle. In some cases culling is the preferable or only remaining option.
Diagnosis of infectious bovine rhinotracheitis
Infectious bovine rhinotracheitis can be initially diagnosed by observing the signs and symptoms which are presented or if there is past history of the disease. However confirmation is required and this is made in the form of taking samples of blood and milk. If antibodies for the bovine herpes virus type 1 are present then this results in a positive test. Nasal and ocular swabs may also be taken, so long as the discharge is still serous, to find the virus. Necropsies can be performed in some cases for a positive diagnosis. The ELISA test is a favoured method in some laboratories.
Prognosis for IBR
Infectious bovine rhinotracheitis is not a disease which usually leads to death. Despite this, if the animal is infected by a secondary bacterial infection then there can be fatal consequences. Cows with reoccurring signs and symptoms are often culled to protect profits. Due to a significant loss in the yield of milk, in some cases, then it is highly unfavourable in terms of the economics of a farmer. This is also true for the growth of beef cattle.