Which of the following is NOT consistent with an outbreak of a foreign animal vesicular disease?

• A. Vesicles on the feet of pigs and cows
• B. Vesicles on the snout of pigs but not horses
• C. Pigs that are fed scraps only
• D. All of the above could be consistent with an outbreak of a foreign animal vesicular disease

Answer: (D)

The key idea is recognizing what signs and factors can occur in a vesicular disease outbreak and that many of these features are compatible with such outbreaks. Foreign animal vesicular diseases typically cause vesicles on mucous membranes and on feet in susceptible species; the distribution and which species are affected can vary with the specific virus and host.

Vesicles on the feet of pigs and cows fit the classic picture you’d expect in diseases like foot-and-mouth disease or vesicular stomatitis. Seeing vesicles on the snout of pigs but not on horses can also occur, depending on the virus strain and species susceptibility, so that pattern can be plausible in an outbreak scenario. Pigs fed scraps (swill feeding) is a well-known risk factor for introducing and spreading vesicular diseases, so that management practice can be associated with an outbreak as well.

Because each of these scenarios could reasonably occur during a vesicular disease outbreak, the statement that all of the above could be consistent with an outbreak reflects that there isn’t a single sign that would rule out such an outbreak. Therefore, the option stating that all of the above could be consistent is the best choice given the question framing.