Vet’s 2025 Guide to Hepatoportal Microvascular Dysplasia (MVD) in Dogs

Vet’s 2025 Guide to Hepatoportal Microvascular Dysplasia (MVD) in Dogs – Tiny Vessels, Big Impact🐾

By Dr. Duncan Houston BVSc

💡 What Is Hepatoportal Microvascular Dysplasia (MVD)?

Hepatoportal microvascular dysplasia (MVD) is a congenital liver condition in dogs where microscopic portal veins are underdeveloped, causing blood to bypass the liver's filtering system. This results in toxin accumulation and metabolic disturbances—even in the absence of visible shunts.

🧬 Breeds & Age at Risk

Breeds: Yorkshire Terriers, Maltese, Cairn Terriers, Shih-Tzus, Pugs, Chihuahuas, Bichons, and several terrier types.
Age: Detected as early as 4–6 months, but many cases present between 1–4 years.

🩺 Symptoms to Watch For

Vomiting and diarrhea
Reduced appetite or picky eating
Poor weight gain or muscle mass
Neurologic signs: confusion, tremors, seizures, "wobbly" gait
Bladder stones or frequent urinary tract infections

🔬 Diagnostic Steps

Bile acid testing: Pre- and post-meal bile acid levels—elevated values suggest reduced liver processing.
Bloodwork: Mildly abnormal liver enzymes, low albumin, low cholesterol, or low BUN.
Ultrasound: Small liver size and reduced portal vein visibility; Doppler can assess blood flow.
Liver biopsy: Confirmatory test showing underdeveloped microvessels without a macro shunt.

💊 Treatment & Management

Prescription diet: Moderate-protein, low-fat, highly digestible (e.g., Hill’s L/D or Royal Canin Hepatic).
Lactulose: Helps trap and eliminate ammonia in the colon.
Antibiotics: For dogs with signs of hepatic encephalopathy or recurrent infections.
Supplements: SAMe, milk thistle, zinc, and Vitamin E for hepatic support.
Avoid hepatotoxic drugs and ensure all medications are dosed appropriately for liver-impaired dogs.

📈 Prognosis

Most dogs with MVD can live normal lives with dietary management and regular monitoring. Severe neurologic or metabolic complications are rare with proper care. Lifelong follow-ups are necessary to maintain wellness and adjust treatment as needed.