North American Veterinary Licensing Examination (NAVLE) Practice Test

The primary differential diagnosis for a litter of pups in which two have died and the others are exhibiting neurological signs is canine herpes virus. This virus is particularly notorious for causing significant mortality and morbidity in neonatal puppies. Canine herpes virus can lead to severe systemic illness, especially in newborns, resulting in clinical signs such as lethargy, poor nursing, and neurological abnormalities. The distribution and severity of clinical signs can vary widely, but the sudden loss of puppies coupled with neurological manifestations in the survivors aligns with this viral infection.

This diagnosis is especially relevant in cases where the mother has not been vaccinated against the virus or if the puppies are exposed to it during the early days of life when they are vulnerable. In contrast, other conditions, such as parvovirus, mostly cause gastrointestinal issues and often affect older puppies rather than neonates directly. Neonatal septicemia could also be a consideration, but it typically presents with more generalized signs rather than solely neurological symptoms. Likewise, transplacental roundworm infections may cause health issues but are less frequently associated with acute neurological signs in this specific context.