Conclusion

The overall incidence of hepatic microvascular dysplasia will likely increase with acceptance of diagnostic criteria, and the disease should be included in the differential diagnoses of animals presenting with signs of hepatic encephalopathy or gastrointestinal disease. Generally, the long-term prognosis for dogs with hepatic microvascular dysplasia appears to be better with medical management when compared with that for dogs with a portosystemic shunt.¹⁰ Dogs in which the disease is diagnosed at 1 year of age or less tend to remain in excellent or good condition with medical treatment.¹⁰ As has been described in the literature and in this case report, the prognosis for dogs with hepatic microvascular dysplasia diagnosed later in life (2 or 3 years of age) is guarded to poor because of medically intractable, recurrent clinical signs.¹⁰ Although neurologic signs often respond well to dietary management (i.e. low protein, highly digestible diets fed long-term), as demonstrated in this case, they, like the gastrointestinal manifestations previously reported in the literature, may have a variable response to treatment, with some patients having refractory clinical signs resulting in marked morbidity.¹⁰

Peter J. Lotsikas, DVM*
John H. Rossmeisl Jr., DVM, MS, DACVIM (internal medicine and neurology)
Department of Small Animal Clinical Sciences
Virginia-Maryland Regional College of Veterinary Medicine
Virginia Tech
Blacksburg, VA 24061

REFERENCES

1. Center SA. Liver function tests in the diagnosis of portosystemic vascular anomalies. Semin Vet Med Surg Small Anim 1990;5:94-99.

2. Flatland B, Leib MS, Warnick LD, et al. Evaluation of the bromosulfophthalein 30-minute retention test for the diagnosis of hepatic disease in dogs. J Vet Intern Med 2000;14:560-568.

3. Rothuizen J, Meyer HP. History, physical examination, and signs of liver disease. In: Ettinger SJ, Feldman EC, eds. Textbook of veterinary internal medicine. Philadelphia, Pa: WB Saunders Co, 2000;1272-1275.

4. Nelson RW. Treatment of complicated hepatic failure. In: Small animal internal medicine. Baltimore, Md: Mosby, 1998;549-550.

5. Summers BA, Cummings JF, de Lahunta A. Degenerative diseases of the central nervous system. In: Veterinary neuropathology. St. Louis, Mo: Mosby, 1995;208-210.

6. Zawie DA, Gilbertson SR. Interpretation of canine liver biopsy. A clinician's perspective. Vet Clin North Am Small Anim Pract 1985;15:67-76.

7. Schermerhorn T, Center SA, Dykes NL, et al. Characterization of hepatoportal microvascular dysplasia in a kindred of cairn terriers. J Vet Intern Med 1996;10:219-230.

8. Phillips L, Tappe J, Lyman R, et al. Hepatic microvascular dysplasia in dogs. Prog Vet Neurol 1996;7:88-96.

9. Allen L, Stobie D, Mauldin GN, et al. Clinicopathologic features of dogs with hepatic microvascular dysplasia with and without portosystemic shunts: 42 cases (1991-1996). J Am Vet Med Assoc 1999;214:218-220.

10. Christiansen JS, Hottinger HA, Allen L, et al. Hepatic microvascular dysplasia in dogs: A retrospective study of 24 cases (1987-1995). J Am Anim Hosp Assoc 2000;36:385-390.

11. Baer KE, Patnik AK, MacDonald JM. Hepatic vascular dysplasia in dogs and cats (105 cases), in Proceedings. 42nd Ann Meet Am Coll Vet Pathol 1991;71.

12. Albillos A, Colombato LA, Enriquez R, et al. Sequence of morphological and hemodynamic changes of gastric microvessels in portal hypertension. Gastroenterology 1992;102:2066-2070.

13. Center SA. Pathophysiology of liver disease: Normal and abnormal features. In: Strombeck's small animal gastroenterology. 3rd ed. Philadelphia, Pa: WB Saunders Co, 1996;573-574.

14. Hopper K, Aldrich J, Haskins SC. Ivermectin toxicity in 17 collies. J Vet Intern Med 2002;16:89-94.

15. Plumb D. Veterinary drug handbook. 3rd ed. Ames: Iowa State University Press, 1999;230:358-361.

16. Mandel NS, Schneider EM, Bosler EM, et al. Intrathecal production of Borrelia burgdorferi-specific antibodies in a dog with central nervous system Lyme borreliosis. Compend Cont Ed Pract Vet 1993;15:581-589.

17. Bleck TP. Central nervous system involvement in Rickettsial diseases. Neurol Clin 1999;17:801-812.