What is the most likely cause of a pruritic cow?

The most likely cause of pruritus in a cow is pseudorabies, which is a viral disease caused by the pseudorabies virus (PRV). This disease is known to affect swine primarily but can also infect cattle, particularly when they are in close proximity to infected pigs. One of the hallmark signs of pseudorabies in cattle is severe itching or pruritus, which can lead to aggressive behavior as the animal tries to relieve the discomfort.

Pseudorabies can lead to neurological symptoms, respiratory issues, and, in some cases, death in affected animals. The pruritus results from the virus's impact on the nervous system, which drives the cow to exhibit this behavior as a reaction to the irritation caused by the infection. Additionally, the presence of pruritus associated with pseudorabies can distinguish it from other diseases, such as foot and mouth disease, which is more characterized by lesions and not primarily itching.

While conditions like rabies and bovine leukemia virus exist, they typically present with different clinical signs, such as neurological dysfunction in the case of rabies or lymphosarcoma in the case of bovine leukemia. Therefore, pseudorabies stands out as the most probable cause of pruritus in