May-Hegglin Anomaly Pug Dog Type (MHA)
May-Hegglin Anomaly Pug Dog type (MHA) is a hereditary blood disorder reported until now only in Pug dog breed. May-Hegglin anomaly belongs in group of disorders known as thrombocytopenia, a medical condition characterized by low blood platelet count in affected animals. Except in pugs, May Hegglin anomaly is affecting also human beings. It is named after German physician Richard May, and Swiss physician Robert Hegglin.
Platelets, or thrombocytes, have a key role in bleeding prevention through clumping of blood vessel injuries. Platelets are produced in the bone marrow and then released into the blood stream. At a site of vascular injury, platelets are exposed to surface which is not from blood vessel, and they initiate to aggregate to each other, which results in formation of a hemostatic plug that will seal the defect.
Characteristics and symptoms
In May-Hegglin anomaly affected pugs, platelets appear to be bigger and their count lower than normal. Changes in neutrophils have been observed as well. The disorder may cause prolonged bleeding time and bruising, which can cause problems post operation. Other than that, no additional clinical signs are usually observed. In human patients, renal disease, hearing problems and cataracts are common, but these symptoms have not been reported in Pugs. Usually, May Hegglin anomaly requires no treatment, except in extreme cases when platelet transfusions may be necessary.
May-Hegglin anomaly pug type (MHA) is caused by mutation of MYH9 gene. The disorder is inherited as an autosomal dominant trait. It is needed one copy of the mutated gene for dog to develop symptoms. When mating healthy, unaffected dog with a heterozygous affected dog, chances are 50% that the cub will be affected as well. The disorder equally affects both female and male dogs.