Canine Parvovirus

Introduction

Until 1978 Parvovirus enteriris was totally unknown in dogs - it was first seen in dogs in Australia where it appeared very similar but perhaps slightly worse than the disease seen in the cat. Research revealed a new and distinct disease, but the virus is very closely related to the feline virus; viral DNA is 98% homologous to the feline virus. Clinically, the virus causes enteritis mainly affecting the small intestine in young dogs over 6 weeks old and myocarditis in puppies. Vaccines are very effective, but the virus is hardy and survives for a protracted time in the environment.

Antigenicity

2 Canine viruses have been identified:
- Canine Parvovirus 1 (CPV1): avirulent and ubiquitous in the canine population
- Canine Parvovirus 2 (CPV2): a new virus that emerged in the late 1970's

Antigenic variants do naturally occur.

Signalment

The virus predominantly affects dogs, but CPV 2a/2b can cause clinical disease in cats.

Pathogenesis

Oropharyngeal infection is followed by viremia. Subsequently there are 2 distinct syndromes:

Myocarditis in puppies aged 3-8 weeks - the virus targets rapidly dividing myocardium leading to sudden death, or fading puppy syndrome. This is now rare due to widespread passive immunity.
Enteritis in puppies >6 weeks of age. The virus targets intestinal crypts, causing the villi to shorten and the destruction of cypt cells, leading to gray, persistent, foul-smelling diarrhoea or hemorrhagic enteritis. CPV has a high morbidity but low mortality (10%) rate.

Epidemiology

Transmission is by the Orofaecal route. The host range is controlled by only a few amino acids

Diagnosis

Haemagglutination or ELISA to confirm viral infection
Viral antigen can be detected in the faeces by the red cell agglutination test
Immunofluorescence
Serology

Prevention and Control

Vaccination, usually given in combination with distemper and hepatitis. With first vaccination at 8-10 weeks and the second vaccination two weeks after the first, 10-12 weeks. Earlier vaccinations can be given where breeders are known to have CPV on the premises.
Thorough disinfection after disease or removing dogs from that area for at least 9 months.