AETIOLOGY AND PATHOGENESIS

Parvoviruses are particularly resistant and can survive for up to six months in the environment, including on surfaces. Transmission is oro-faecal. The incubation period in cats and dogs is between three and seven days and virus can be shed in faeces for up to three days before the first symptoms appear, i.e. animals are contagious before showing symptoms.

Parvovirus has a preference for actively dividing cells such as those found in the intestines and bone marrow, and sometimes the heart (in puppies) and immune cells. By attacking bone marrow and cells of the immune system, the virus prevents the development of immune defences. This makes it very difficult for animals to fight off the infection.

In utero transmission from mother to foetus is possible. In kittens, this results in cerebellar hypoplasia (underdevelopment of part of the brain, leading to locomotor problems), while puppies are more likely to suffer from myocarditis (inflammation of the heart muscle), although this form is rare.

CLINICAL SYMPTOMS

In both species, the infection primarily affects young, unvaccinated animals, which may die as a result. In fully grown individuals, the infection is usually subclinical.

Kittens between 6 and 14 weeks old present with fever, vomiting and bloody diarrhoea. They quickly become lethargic, weak and dehydrated, and can eventually become hypothermic.

Puppies between the age of 6 and 16 weeks are especially vulnerable, presenting with vomiting, fever and profuse bloody, foul-smelling diarrhoea. Bacterial superinfections are common and death can occur within 48 to 72 hours. Lethality can exceed 70% in puppies with compromised immunity, but is no more than 1% in healthy, adult animals.

The course of the disease depends on many factors (the animal’s general health, comorbidities, promptness of care and form of the disease), with the outcome ranging from death within a few hours to recovery after a few days. After recovery, dogs continue to be carriers for two weeks; recovered cats may develop a chronic infection and remain contagious for longer.

DIAGNOSIS

Diagnosis is made on the basis of a typical profile: young dog or cat, not or only partially immunised, usually aged between 6 weeks and 6 months.

The symptoms mentioned above are typical and significantly inform the diagnosis. Blood tests show a lowered white cell count.

Rapid diagnostic tests are commonly available. These are reliable but must be carried out under optimum conditions to avoid false results. Other tests are available via laboratories.

The differential diagnosis should rule out alternative causes of acute diarrhoea, such as bowel obstruction, parasitic diarrhoea (coccidiosis) and other viral or bacterial diseases affecting the intestines.

TREATMENT

Immediate, intensive treatment is required. The animal is put on a drip to prevent dehydration and alleviate shock. Anti-vomiting medication is essential. The diarrhoea is stopped using Digest Regul™, which absorbs excess fluid, slows down intestinal transit and replaces lost NaCl.

Antibiotics are administered to combat secondary bacterial infections. A blood transfusion is sometimes necessary. Occasionally, if the animal is not eating, protein and nutrient losses should be offset by placing a feeding tube.

Energy Supp™ can additionally be prescribed, as it provides many amino acids and nutrients. It also contains spirulina, which stimulates the production of white and red blood cells and is very high in protein. Immune Supp™ can help boost the effectiveness of the immune system.

Other treatments can also be considered on a case-by-case basis, including deworming tablets and analgesics.

PREVENTION

Maternal immunity is conferred through antibodies in the mother’s colostrum, but maternal antibodies only protect newborns for a few weeks. Puppies and kittens between 8 and 12 weeks old are in a phase known as the “immunological gap”: the antibodies received from their mother no longer fully protect them against infection, but still interfere with vaccination, making it less effective.

Vaccination is the best way to protect your pet, in combination with hygiene measures while their immune system is still vulnerable.

Dr Isabelle de Grand Ry
DMV | GPCert In Small Animals Surgery
Vet Center l’ETOIL
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