Parvoviral myocarditis in puppies: sudden death

Question

At a breeder with no vaccination programme, a young, never-vaccinated bitch has a litter of 7 puppies. At 6 weeks, three die suddenly after a brief episode of dyspnoea, with no vomiting or diarrhoea. Necropsy shows cardiac dilation with pale streaks in the myocardium.

Which statement about this condition is correct?

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A. It is the typical form of parvovirus in vaccinated puppies over 4 months of age

The cardiac form only appears when infection occurs in utero or in the first weeks of life without maternal antibodies. In older puppies the typical form is enteric.

B. The most likely cause is canine herpesvirus, which causes myocardial necrosis

Canine herpesvirus mainly kills puppies under 3 weeks of age, with multiorgan petechial haemorrhages (kidney, lung, liver), not myocarditis at 6 weeks.

C. It is parvoviral myocarditis: the virus replicates in cardiomyocytes, which are still dividing in the first weeks of life

Correct. Parvovirus needs dividing cells. In puppies infected before ~8 weeks without maternal antibodies, it replicates in the myocardium and causes sudden death or heart failure weeks or months later.

D. The surviving littermates will be protected for life and do not need vaccinating

You cannot know which puppies were infected; some survivors may develop heart failure later and uninfected ones remain susceptible. They must be vaccinated and monitored.

lightbulb Key takeaway

Parvoviral myocarditis is rare today because almost all bitches have antibodies (from vaccination or infection) that protect the litter in its first weeks. If it reappears, suspect unvaccinated dams in breeding or group settings: vaccinating the bitch before mating is the prevention.

Which statement about this condition is correct?

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