Canine Hepatic Calodiosis with Cirrhosis

Abstract

Parasitic zoonoses from dogs are less frequent although dogs are reservoirs for many zoonotic parasites. The nematode parasite Calodium hepaticum (Capillaria hepatica) has a global distribution and is commonly reported in rodents (definitive host), dogs, cats and wild animals. Humans especially children are more susceptible to the parasitic infection. This paper documents an incidental finding of hepatic calodiosis with cirrhosis in a stray dog and discusses the zoonotic implications. A nondescript dog was brought for necropsy examination to the Department of Veterinary Pathology, Madras Veterinary College, Tamil Nadu, India. Liver appeared dark brown mottled with multifocal random variably sized, grey white flat firm areas. Histopathologically, liver tissue revealed multiple random encysted large collection of eggs surrounded by mild inflammation with a few lymphocytes, macrophages and fine fibrosis. The eggs had characteristic barrel shape, bipolar ends, bilayered wall, cross striations between the walls, and yolk. Periodic acid Schiff stain demonstrated the glycolic wall of ova. Marked portal to portal fibrosis was demonstrated for collagen by Masson’s trichrome and for reticulin by Warthin-Starry stains. The stage of parasitic infection was diagnosed as intermediate to chronic due to fibrosis. A need to study the prevalence of the disease in human and animals and attempts for early diagnosis is emphasized. A caution in general about the zoonotic threat to children/pet parents/ veterinarians/animal handlers caused by C. hepaticum infection which is poorly diagnosed and sporadically reported in India and worldwide.