Congenital erythropoietic protoporphyria and protoporphyric hepatopathy in a dog

CASE DESCRIPTION A 6-month-old sexually intact male Clumber Spaniel was evaluated because of small stature, recurrent dermatitis of the head, and progressive pigmentary hepatopathy. CLINICAL FINDINGS Clinicopathologic findings included nonanemic hypochromic microcytosis, hypocholesterolemia, persistently high serum liver enzyme activities, and anicteric hyperbilirubinemia. Histologic examination of liver biopsy specimens collected when the dog was 6 months and 2 years of age revealed expansion and bridging of portal tracts, occasional centrilobular parenchymal collapse, scattered lymphoplasmacytic infiltrates, and dark red to brown pigment within large aggregates of macrophages, engorged bile canaliculi, and hepatocytes. The pigment failed to stain for the presence of iron, copper, bile, and glycoprotein and, when examined with polarized microscopy, emitted a yellow to green birefringence with occasional Maltese cross configurations. Further analyses confirmed marked porphyrin accumulation in blood, urine, feces, and liver tissue; protoporphyrin accumulation in RBCs and liver tissue; and a signature porphyrin profile and fluorescence peak consistent with erythropoietic protoporphyria. Advanced protoporphyric hepatopathy was diagnosed. The chronic dermatopathy was presumed to reflect protoporphyric photosensitivity. TREATMENT AND OUTCOME Management was focused on avoiding conditions known to induce heme synthesis and catabolism, administrating ursodeoxycholic acid and antioxidants Sadenosylmethionine and vitamin E, and avoiding sunlight exposure. At follow-up at 4 years of age, the dog was stable without evidence of jaundice but with probable persistent erythropoietic protoporphyria–related solar dermatopathy. CLINICAL RELEVANCE Clinical and histologic features of congenital erythropoietic protoporphyria and resultant protoporphyric hepatopathy, the diagnosis, and the successful management of a dog with these conditions over 4 years were described. Veterinarians should consider porphyric syndromes when unusual pigmentary hepatopathies are encountered.