Pashu Sandesh, 17 July 2021
Vinay Waskel, Pratibha Yadav, Rahul Khatri, Daljeet Chhabra, Rakesh Sharda, Joycee Jogi, Rakhi Gangil and Ravi Sikrodia
Department of Veterinary Microbiology, Co.V.Sc. & A.H., Mhow
Canine Parvovirus (also called CPV, CPV2, or Parvo) was first discovered in 1978 and became one of the major health issues for domestic and wild canids. Canine Parvovirus is a highly contagious virus with high morbidity (100%) and frequent mortality up to 10% in adult dogs and 91% in pups. CPV-2 and CPV-1 are two distinct pathogenic strains. CPV-2 is responsible for causing acute haemorrhagic enteritis and myocarditis in dogs. Further CPV-2 has 3 variants namely CPV-2a, CPV-2b and CPV-2c.
‘Parvo’ means small (Latin), Canine Parvovirus comes under the family Parvoviridae and genus Parvovirus. It is a non-enveloped, single-stranded negative-sense DNA virus.
Canine Parvovirus is transmitted through the faecal-oral route or contaminated surfaces (eg. soil, shoes, dog toys etc.) from infected dogs. CPV is hardy and can remain on faeces contaminated surfaces for 5 months or more.
Through the oral route, the virus enters the body. After 3-7 days of incubation period dog starts to show the clinical signs and symptoms. After entering into the body, it replicates in the lymph nodes. After few days, a significant amount of the virus has been released into the bloodstream, causing viremia. This leads to the circulation of the virus to new organs (intestine, heart, bone marrow etc.). Within the bone marrow, the virus destroys the young immune cells, leads to immune failure. It is characterised by a drop in WBC count.
In the intestine, the virus causes heavy damage to intestinal cells, results in bloody diarrhoea. Diarrhoea and vomiting lead to extreme fluid loss and dehydration results in shock and death.
Signs and symptoms:
Diarrhoea occurs in dogs of any age but is more serious in the case of pups. Early symptoms are depression, loss of appetite, vomiting, high fever and diarrhoea. There is a slight rise in temperature in the initial stage of the disease but gradually drops to subnormal as severity increased. The consistency of the stool may not be the same, it may be watery, yellow in colour or tinged with flank blood in severe cases. Death occurs within 3-5 days after the onset of symptoms due to severe diarrhoea and vomiting.
6 months or below the age of pups are mainly affected by this form. Also known as a cardiac syndrome, or myocarditis. Acute heart failure causes sudden death in pups, less common in adult dogs.
Congenital anomalies may occur in newborn pups when the pregnant dog is infected with the CPV2 in case of mild to moderate infections. In severe cases fetus may die.
A tentative diagnosis of CPV can be made on the basis of clinical signs and symptoms (like bloody diarrhoea and vomiting) and history of dog etc.
Serological & Molecular Techniques used for Diagnosis:
It includes HA (haemagglutination), electron microscopy, latex agglutination, fluorescent antibody test (FAT), virus neutralization test (VNT), ELISA, real-time PCR, loop-mediated isothermal amplification and nucleic acid sequencing etc.
Control and prevention:
Primary vaccination should be done after 30 days of birth. A booster should be given after 1 month of primary vaccination and repeat annually.
Survival chances are as low as 9% if there’s no treatment and it depends on how quickly CPV can be diagnosed, the age of the dog and the course of treatment etc.
For restoration of dehydration fluid therapy should be started as soon as possible. Symptomatic treatment includes anti-viral, broad-spectrum antibiotics, anti-diarrheal and antiemetics.
Stomach cramps occur frequently due to severe enteritis in Canine Parvovirus infection. For pain management analgesic treatment should be given to the dog. Ice packs or a cold towel can also be wrapped around the belly region to reduce pain.