Farm Ireland

Saturday 17 March 2018

Calf health: Mystery killer

A strange bleeding disorder which strikes at young calves has European scientists perplexed as to its origin and possible cure

Dr Ingrid Lorenz

A mysterious bleeding disorder in young calves has emerged across Europe and is claiming the lives of most animals affected with the disease.

The 'bleeding calf syndrome' was first detected in Germany in 2007 and has since been reported in Belgium, France, Italy, the Netherlands, and Great Britain.

Affected calves are born perfectly healthy but, soon after birth, they suffer from a total depletion of bone marrow. At present it is thought that some form of immunological reaction is responsible for the destruction of the bone marrow cells, which results in calves having very low blood counts of white cells and platelets.

Since white blood cells are necessary for a normal immune response to infectious diseases, these calves are more likely to develop common calf diseases, such as scours or pneumonia, than normal calves. In many cases the clinical picture of the bleeding disorder is only detected during treatment of the initial disease. Platelets are necessary for the process of blood clotting, and therefore the absence of platelets in the blood of affected calves explains the abnormal bleeding.

Affected calves often show prolonged bleeding from injection sites or after tagging, while another constant finding is the presence of variable amounts of blood mixed with normal or diarrhoeic faeces.

Spontaneous bleeding from tiny skin lesions leads to the most spectacular clinical picture and gave rise to the colloquial term "blood sweating". However, this form of the disease mainly occurs during the summer period and is thought to be linked to insect bites. Less common findings include point-shaped bleeding on the gums, bleeding within the eyes, and haematomas under the skin. Some calves develop only internal bleeding and are therefore only detected in post-mortem examinations.

Most of the calves developing the disease die, despite intensive treatment including blood transfusions.

Affected calves are often less than one month old, and of any breed, with both dairy and beef breeds represented. In most cases the disorder affects one or a few calves on each farm, but some farms have lost as many as 40 calves over a period of three years. Findings on these multiple-case farms point to the possibility of a genetic predisposition to the disease.

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BVD virus, which is known to cause a bleeding disorder, was ruled out as a cause of the condition early on, as was Bluetongue virus, the European spread of which coincided with the occurrence of the disease.

Calves usually show antibodies against BVD, since most of the dams have been vaccinated. The syndrome also appeared before vaccination against Bluetongue was introduced.

Current research indicates that the disorder is probably not caused by a single toxic or infectious agent, but by a combination of factors affecting the dam and the calf.

At present, no cases have been confirmed in the Republic of Ireland. However, as there is no difference between Ireland and the countries where the disease has been reported, it would be important to know if this reflects the true situation.

The regional veterinary laboratories and the herd health group of UCD are available to assist herd owners and veterinary practitioners with the investigation of suspicious cases.

Irish Independent