Parvoviruses (PV) can cause outbreaks with high morbidity and mortality in dogs and cats. Even if typical cases exist in puppies and kittens, PV infection (PVI) can have many different clinical presentations, making the laboratory support necessary. The aim of this work was to evaluate retrospectively the frequency of misdiagnoses, particularly missed diagnoses, of PVI in 144 suspected cases (88 clinical cases and 56 necropsies) involving 96 dogs and 48 cats. A nested PCR test was chosen as the gold standard. An index of diagnostic suspicion (IDS) for PVI, based on parameters reported upon submittal of the samples, was introduced to classify the initial diagnoses issued by veterinarians. The agreement between the IDS of PVI and PCR results was calculated. The effect of species, age and clinical versus necroscopic presentation was evaluated by logistic regression. In 63.6% of the cases, the IDS was confirmed by the PCR, whereas in 36.4% there was a missed diagnosis or a diagnosis wrongly attributed to PVI. More accurate results were obtained for dogs, animals aged < 1 year, and necropsies. Parvovirus infection should be better investigated in patients with atypical or few clinical signs, in particular in cats and animals over 1 year old.