Host range — Among the animal species listed, which is classically considered most susceptible to rabies infection?

Introduction / Context:
Rabies affects all mammals to varying degrees, but practical public health emphasis is on species with high susceptibility and close human contact. Reservoirs and vectors vary by region, with dogs representing the dominant source of human exposures in many countries.

Given Data / Assumptions:

• All mammals are susceptible; birds (fowl) are relatively resistant and rarely infected.
• In endemic regions, domestic dogs constitute the principal reservoir and transmit most human cases.
• “Most susceptible” in basic MCQs usually contrasts mammals with avian species and highlights the dog’s epidemiological role.

Concept / Approach:
Between the provided options, dogs are both highly susceptible and epidemiologically central. Cats and cattle can be infected, but dogs contribute the majority of human rabies deaths worldwide due to frequency of bites and urban reservoirs.

Step-by-Step Solution:

Verification / Alternative check:
Global health data consistently attribute most human rabies transmissions to dog bites in endemic areas.

Why Other Options Are Wrong:

• Cat: susceptible but less central globally.
• Cow: herbivore; cases occur but do not drive human epidemics.
• Fowl: relatively resistant; not a typical host.

Common Pitfalls:
Confusing reservoir importance with mere possibility of infection; practical susceptibility and transmission risk point to dogs.

Final Answer:
dog