Overview

• CCoV-sporadic outbreaks of vomiting and diarrhea in dogs; worldwide distribution.
• CRCoV-associated with canine infectious respiratory disease complex (“kennel cough”); worldwide distribution.
• Infection with CCoV-usually inapparent; mild to severe enteritis may occur, from which most dogs recover; death reported in young pups; restricted to the upper two-thirds of the small intestine and associated lymph nodes; unlike CPV-2 infection, crypt cells spared.
• Simultaneous infection with CPV-2 may occur; more severe; often fatal.
• Coronaviruses undergo rapid evolution, are highly variable, and differences in virulence between individual isolates are likely.

Signalment

• Only dogs susceptible to disease.
• CCoV may cause inapparent infections in cats.
• CRCoV infections more common in the winter.
• All ages and breeds.
• Disease more severe in young animals.

Signs

• Vary greatly. Rarely virulent isolates that cause systemic disease can occur.
• Adults-most infections inapparent.
• Puppies-may develop mild to severe, occasionally fatal enteritis.
• Incubation period 1–3 days.
• Sudden onset of vomiting, usually only once.
• Diarrhea-may be explosive; yellow-green or orange; loose or liquid; typically malodorous (characteristic); may persist for a few days up to >3 weeks; may recur later.
• Coughing; CRCoV associated with canine kennel cough complex.
• Young pups-may suffer severe, protracted diarrhea and dehydration.
• Anorexia and depression common.
• Fever rare.
• Mild respiratory effects.
• Signs included pyrexia, anorexia, depression, vomiting, hemorrhagic enteritis, respiratory distress, and leukopenia that persisted >1 week. Ataxia and seizures also occurred in pups, with deaths in 2 days after onset of symptoms.

Causes & Risk Factors

• CCoV-closely related to FIP virus, feline enteric coronavirus, and transmissible gastroenteritis virus of swine; pig and cat viruses not known to cause natural illness in dogs; readily inactivated by common disinfectants.
• CRCoV-genetically and serologically distinct from CCoV; more closely related to bovine coronavirus and human coronavirus OC43.
• Stress (e.g., intensive training, crowding)-greatest risk; sporadic outbreaks have occurred in dogs attending shows and in kennels where introductions of new dogs are frequent; crowding and unsanitary conditions promote clinical illness.
• For CCoV, feces primary source of infection; virus shed for about 2 weeks.
• For CRCoV, respiratory secretions and fomites are likely sources of infection.

Differential Diagnosis

• Infections caused by enteric bacteria, protozoa, or other viruses and other agents associated with kennel cough complex.
• Other causes of mild to moderate upper respiratory disease.
• Food intoxication or intolerance.

CBC/Biochemistry/Urinalysis

Normal; lymphopenia with more virulent CCoV isolates.

Other Laboratory Tests

• Serologic tests-available; not standardized.
• Antibody titers-generally low; may not indicate recent infection because of high rate of asymptomatic infection.

Diagnostic Procedures

• Viral isolation for CCoV-from feces in feline cell cultures at onset of diarrhea. Viral isolation for CRCoV is difficult and not recommended.
• PCR-using type-/strain-specific probes.
• Immunofluorescence of the small intestine-fatal cases; may reveal viral antigen in cells lining the villous epithelium.

Pathologic Findings

• Gross-may be dilated loops of small intestine filled with gas and watery green-yellow material.
• Bowel loops may be congested or hemorrhagic; mesenteric lymph nodes usually enlarged and edematous.
• Typical microscopic changes-atrophy and fusion of intestinal villi; deepening of the crypts; increased cellularity of the lamina propria; flattening of epithelial cells with increased goblet cells.
• Lesions-commonly obscured by post-mortem autolysis.
• The “Pantropic” strains described in Europe caused hemorrhagic lesions in the lungs, small intestines, kidneys and lymph nodes, and serosanguineous abdominal fluid.

Drug(s)

Antibiotics-not usually indicated, except with enteritis, sepsis, or respiratory illness.

Prevention/Avoidance

• Vaccines-controversial; inactivated and live viral vaccines available; appear to be safe; efficacy unknown, except for brief periods (2–4 weeks) after vaccination. Not recommended. Vaccines for CCoV do not cross-protect against CRCoV.
• Strict isolation and sanitation are essential in kennels.
• CCoV and CRCoV-highly contagious; spread rapidly.

Possible Complications

Diarrhea with CCoV-may persist 10–12 days; may recur.

Expected Course and Prognosis

• Prognosis-normally good, except severe infections of young pups.
• Majority recover after a few days of illness.

Associated Conditions

• Infection with canine parvovirus or other agent may occur concurrently.
• Infections with other respiratory pathogens are commonly associated with CRCoV.

Abbreviations

• CCoV = canine enteric coronavirus
• CPV = canine parvovirus
• CRCoV = canine respiratory coronavirus
• FIP = feline infectious peritonitis
• PCR = polymerase chain reaction