Which parasite infection is characterized by severe anemia in pets?

Hookworm infection is characterized by severe anemia in pets due to the blood-feeding habits of these parasites. Hookworms attach to the intestinal lining and can consume significant amounts of blood from the host animal. This can lead to a rapid decline in red blood cell count, resulting in anemia. In cases of heavy infestations, the loss of blood could be substantial, causing symptoms such as pallor, weakness, lethargy, and in severe instances, it can be life-threatening.

In contrast, tapeworm infections typically do not cause anemia. Instead, these parasites lead to issues such as weight loss and gastrointestinal discomfort, mainly because they compete for nutrients rather than directly blood-feeding. Flea infestations can also lead to anemia, particularly in young or weakened animals, but it's more commonly associated with secondary issues rather than being a primary consequence of the infestation. Heartworm infections, while serious and capable of causing various health problems, do not typically result in anemia in the same direct manner as hookworms do; their primary impact is on the heart and lungs.

Thus, hookworm infections stand out for their direct and severe impact on red blood cell levels, clearly making them the key focus regarding severe anemia in pets.