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Bleeding disorder

Bleeding disorder is one of the many hereditary diseases the dog has in common with human beings. It has been already studied and described in a great deal of breeds. Of the Japanese breeds the Akita and the Shiba have been affected.

A defect in the haemostasis, i.e. in the process of blood clotting and stanching, is referred to as bleeding disorder. Normally when a blood vessel is damaged, mechanisms are started up which seal the wall of the damaged vessel to prevent a larger loss of blood. If a blood clotting factor is missing or impaired, continued bleeding is the result.

Typical symptoms of bleeding disorder are frequent haematomae, bleeding of the joints, very strong bleeding when the bitch is in heat, bleeding problems with injuries or during surgery, internal bleeding.

The three most common types of bleeding disorder are:

Haemophilia A
is the most common hereditary blood clotting defect in human beings as well as in animals. The reason is a deficiency or lessened activity of the factor VIII which plays a decisive role in blood clotting.

The affected Aktias and Shibas were suffering from this kind of the disease. [1]

Haemophilia B (Christmas Disease)
is diagnosed clearly less frequently. The animals fall ill because of a lack of factor IX which also has a key role in blood clotting.

Von Willebrand Disease
is the second most common bleeding disorder. The von Willebrand disease is a blood clotting dysfunction of varying severity resulting from a defective or missing von Willebrand factor (vWF) in the blood. The vWF is an important factor in blood clotting having the function of stabilising factor VIII in the blood. There are three variations of this disease (type 1-3).

How is blood disorder inherited?

The inheritance of haemophilia A and B is recessive with the peculiarity that this disorder appears only in a specific sex (so-called gonosomal or sex-linked heredity).

Haemophilia develops if an X chromosome has a special defect. In bitches this occurs normally in combination with an intact X chromosome and does not entail any symptoms. Only in the combination of a defect X chromosome with a Y chromosome (i.e. only in males) does the dysfunction become manifest in the lack of a clotting factor. For this reason haemophilia is also referred to as an "X chromosome-linked" disorder.

The von Willebrand disease is inherited autosomal-recessively. With type 1 a dominant heredity disposition is also possible.

Diagnosis and therapy

The symptoms of haemophilia A and B are very similar due to their closely related causes. They often appear at an early stage. Affected whelps can often be identified by continued umbilical cord bleeding immediately after birth. Also during second dentition these animals keep bleeding extraordinarily heavily and enduringly.

There are several techniques available for recognising the causes of defects in the blood clotting system. In recent times due to DNA tests a very reliable determination of carriers, wholesome and hereditarily insane dogs has also been possible. With some breeds testing for bleeding disorder is mandatory, e.g. for the Scottish Terrier.

Depending on the severity of the disease the prognosis for affected dogs tend not to be favourable.

Because presently there are no methods of treatment available for dogs suffering from bleeding disorder the spread has to be limited by excluding affected dogs from breeding. Very important is the recognition of bitches which are not affected themselves but are carriers.

Reference

[1] M. Brooks: A review of canine inherited bleeding disorders: biochemical and molecular strategies for disease characterization and carrier detection, The Journal of Heredity 90 (1999), pp. 112-118.