What clinical sign would suggest a parasitic infection in goats related to Haemonchus contortus?

The presence of anemia is a significant clinical sign that suggests a parasitic infection in goats, particularly when considering Haemonchus contortus, commonly known as the barber pole worm. This particular parasite is a blood-feeding nematode that resides in the abomasum of ruminants, leading to the significant loss of red blood cells and subsequent development of anemia.

Infected goats may exhibit pale mucous membranes, lethargy, and weakness, all of which can be attributed to the reduced red blood cell count resulting from the parasite's feeding. Monitoring for anemia is crucial in managing goat herds, especially since Haemonchus contortus is prevalent in many regions and can lead to severe health issues or even mortality if not addressed promptly.

While other clinical signs such as excessive shedding of fur, respiratory distress, or abnormal appetite may be associated with different health issues in goats, they are not as specifically indicative of an infection with Haemonchus contortus as anemia is. Thus, anemia is a key indicator of this parasitic infection, making it the correct choice in identifying potential issues stemming from this particular parasite.