Understanding and Managing Hepatic Microvascular Dysplasia in Dogs
Hepatic microvascular dysplasia (MVD) is a congenital or inherited disorder affecting the liver’s microscopic blood vessels. Also known as portal vein hypoplasia, MVD is most commonly seen in small-breed dogs and can vary significantly in severity. While this condition is not curable through surgery, it is often manageable with careful medical attention and lifestyle modifications.
What Is Hepatic Microvascular Dysplasia?
Hepatic MVD involves underdeveloped or absent portal veins within the liver. These veins are crucial for carrying blood rich in nutrients from the intestines to the liver for detoxification and metabolism. When these microscopic vessels are malformed or missing, the liver receives reduced blood flow, which can impair its function.
Breeds at Risk
Some breeds show a higher predisposition to MVD. These include:
- Yorkshire Terriers
- Cairn Terriers
- Maltese
- Miniature Poodles
- Shih Tzus
- Lhasa Apsos
- Cocker Spaniels
- West Highland White Terriers
- Dachshunds
- Bichon Frises
While rare in large breeds and cats, isolated feline cases have been documented.
Symptoms
Many dogs with MVD show
no signs at all, especially in mild cases. However, some may experience:
- Poor weight gain or growth
- Lethargy or reduced alertness
- Vomiting or diarrhea
- Increased thirst and urination
- Urinary tract issues including stones or infections
- In serious cases, neurological symptoms like seizures or disorientation
Diagnosis
Diagnosing MVD involves a multisystem approach:
- Blood Tests: May show anemia, low albumin, or increased liver enzymes
- Urinalysis: Can reveal dilute urine or ammonium biurate crystals
- Serum Bile Acid Test: Measures pre- and post-meal bile acids; mild to moderate elevation suggests MVD
- Protein C activity test: Typically normal in MVD, reduced in larger shunts
- Imaging: Ultrasound, CT, or MRI may rule out larger portosystemic shunts
- Liver Biopsy: Confirms diagnosis with evidence of microscopic vascular changes
Needle biopsies are avoided due to the small sample size and limited diagnostic value. Collecting samples from multiple liver lobes improves diagnostic accuracy.
Treatment Options
There is no
surgical cure for MVD. However, various treatment strategies help manage symptoms or prevent complications.
For asymptomatic or mildly affected dogs:
- No specific treatment may be required
- Periodic monitoring of liver function and health status
For dogs with more pronounced symptoms:
- Dietary Management: Low-protein diets with digestible, high-quality protein sources like soy or dairy
- Lactulose: Helps reduce intestinal ammonia absorption
- Antibiotics: Metronidazole or other antibiotics may help in short-term management
- Supplements: SAMe, vitamin E, milk thistle, and others may offer liver support
- Probiotics and yogurt: Used to support gut health, although efficacy is uncertain
Prognosis
Many dogs with MVD lead
normal, full lives. The condition is often non-progressive, especially in the absence of overt signs. Regular check-ups, including liver function panels and symptom monitoring, are recommended. Bile acid levels, once elevated, may remain stable for long periods and don’t need constant retesting.
Breeding Considerations
Since MVD is believed to be hereditary and follows a
polygenic inheritance pattern, breeding affected dogs is strongly discouraged. Even dogs with normal bile acids may carry genes linked to MVD and pass them to offspring.
Key Takeaways
- MVD is a congenital liver disorder common in small breeds
- Symptoms vary widely, and many dogs may remain asymptomatic
- No surgical correction exists, but medical management is effective
- Regular health checks and dietary management support long-term well-being
- Breeding avoidance is crucial to reduce future incidence
MVD demands knowledgeable care and attention, but many dogs still enjoy healthy and active lives with proper management.
