Hepatic microvascular dysplasia (HMD) or portal atresia is a histologic diagnosis, meaning it only describes the biopsy findings. In fact, there are many conditions that can cause these findings, including congenital portosystemic shunts; however, when the diagnosis is made without evidence of a congenital shunt, then the dogs are often given the diagnosis of HMD as a specific disease.
Clinical presentation of microvascular dysplasia in dogs
Dogs with HMD can present with signs similar to dogs with congenital portosystemic shunts; however, many dogs have no clinical signs at all. Often affected dogs are 3 to 4 years old before they have clinical signs. Some affected dogs are smaller than normal, with poor muscle development. They may seem less intelligent or quieter because of the toxins that depress their brains. They may have a loss of appetite or occasional bouts of vomiting and diarrhea. Some dogs may have a greater risk of infections or develop bladders stones. Severely affected dogs may be wobbly or act drunk or blind and can even seizure. Rarely, dogs will develop fluid filled bellies from liver failure.
Learn more about MVD from the surgical specialists at ACVS:
NB: I find that medical and dietary management of these patients in my practice to be very rewarding. Many MVD and portosystemic shunt patients can live normal lives. There is plenty of great info and support on the internet for the guardians of these patients.