Hepatic microvascular dysplasia is also known as HMD or portal atresia, and refers to a condition in dogs where the liver's vessels are abnormal. This diagnosis is determined after a biopsy, and several small breeds of dog are more at risk to be affected.
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Cause
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As with any living creature, when the vessels in a dog's liver are missing or underdeveloped the liver gets smaller, or atrophies. An atrophied liver can't function properly--it can't process the body's toxins or make necessary proteins. Dogs with this condition receive a diagnosis of hepatic microvascular dysplasia.
Symptoms
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Hepatic microvascular dysplasia should not be confused with congenital portosystemic shunts. Most dogs affected with HMD are 3 to 4 years old before they develop symptoms, which include poor muscle development, seemingly abnormally quiet or less intelligent than their breed typically is, bouts of diarrhea and vomiting, loss of appetite, development of bladder stones, frequent infections, seizures and development of a fluid-filled stomach.
Risk
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The breeds most commonly affected are Cairn terriers and Yorkshire terriers, and other small breeds are at risk for developing the disease as well: dachshunds, Malteses, Shih tzus, cocker spaniels, West Highland white terriers, miniature poodles, and Lhasa apsos.
Diagnosis
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Before being diagnosed with HMD, the possibility of shunts must be ruled out. Because of this, the diagnosis comes after a liver biopsy and other tests, including portograms, CT angiograms and scintigraphies. Urine monitoring, bile acid measurement, and basic biochemical tests are also taken to come to a conclusive diagnosis.
Treatment
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No surgical treatment for HMD exists, and the condition is managed depending on its severity. Some dogs do not receive treatment at all, while most undergo a diet change, namely reducing protein intake. Additional dietary adjustments include adding more zinc and vitamin E.
Other treatment options: giving the dog yogurt, antibiotics, or lactulose syrup to decrease toxin production and absorption in the intestines; administering nutriceuticals; taking Denosyl or milk thistle to improve liver function.
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