Canine Parvovirus

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Source: Wikimedia Commons; Author: ZaldyImg (2008)

Introduction

Until 1978 Parvovirus enteritis 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. The virus is transmitted orally. 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, these are Canine Parvovirus 1 (CPV1): avirulent and ubiquitous in the canine populationand Canine Parvovirus 2 (CPV2): a new virus that emerged in the late 1970'. Antigenic variants do naturally occur.

Pathogenesis

Oropharyngeal infection is followed by viremia. Subsequently there are 2 distinct syndromes depending on the age of the animal:

1. 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.
2. 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.
   

Diagnosis

Often the clinical signs plus history, signalment and lack of vaccination is very indicative of the virus. Haemagglutination or ELISA to should be performed to confirm viral infection. Viral antigen can be detected in the faeces by the red cell agglutination test. Immunofluorescence and serology can also be used to diagnose this disease.

Treatment and Control

In an outbreak, affected dogs need to be kept isolated. Supportive care needs to be given such as intravenous fluid therapy. Antibiotics are sometimes given to protect against or treat any seconday bacterial infections that may ensue.

Vaccination is widely avaliable and is recommended by all vets for puppies. The vaccine is given in combination with Distemper, Hepatitis and Parainfluenza viruses. First vaccine is given 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.

References

Ettinger, S.J. and Feldman, E. C. (2000) Textbook of Veterinary Internal Medicine Diseases of the Dog and Cat Volume 2 (Fifth Edition) W.B. Saunders Company
Nelson, R.W. and Couto, C.G. (2009) Small Animal Internal Medicine (Fourth Edition) Mosby Elsevier.
Tilley, L.P. and Smith, F.W.K.(2004)The 5-minute Veterinary Consult (Third edition) Lippincott, Williams & Wilkins.

Literature Search

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Canine parvovirus: an emerging, re-emerging, significant pathogen of dogs. Kapil, S.; The North American Veterinary Conference, Gainesville, USA, Small animal and exotics. Proceedings of the North American Veterinary Conference, Orlando, Florida, USA, 17-21 January, 2009, 2009, pp 650-651, 3 ref. - Full Text Article