Canine Coronavirus-Associated Puppy Mortality without Evidence of Concurrent Canine Parvovirus Infection

This report presents 2 cases in which puppy fatalities were associated with canine coronavirus (CCV), but no evidence of concurrent canine parvovirus (CPV-2) disease was observed. Case 1 involved a 7-week-old, male short-haired Chihuahua, which had become lethargic 24 hours after purchase from a pet store. Within 72 hours, the puppy began to vomit, had diarrhea, and was admitted to the veterinary clinic, where it was placed on IV fluids. The parvovirus Cite test was negative. The puppy died within 12 hours of admission and was submitted for diagnostic workup. Gross pathology revealed an enteritis suggestive of CPV-2. Histopathology on intestines showed scattered dilated crypts with necrotic cellular debris and neutrophils. There was moderate depletion and necrosis of lymphoid follicles. Electron microscopy (EM) on intestinal contents was positive for coronavirus and negative for parvovirus. Immunohistochemistry (IHC) on gut sections was positive for CCV and negative for CPV-2. Case 2 was an 8-week-old, male Shih Tzu, which was admitted to the veterinary clinic exhibiting symptoms of severe gastroenteritis with abdominal pain. The referring veterinarian euthanized the puppy, and the entire body was submitted for diagnostic evaluation. Necropsy revealed a severe ileo-cecal intussusception and segmental necrotic enteritis of the small intestine. Electron microscopy of the intestinal contents was positive for coronavirus and negative for parvovirus. Immunohistochemistry on sections of affected gut were positive for CCV and negative for CPV-2. These cases emphasize the importance of pursuing a diagnosis of CCV in young puppies when CPV-2 disease has been ruled out by IHC.