Which parasite primarily affects the intestines of dogs and cats?

Roundworms are a common intestinal parasite that primarily affects dogs and cats. These parasites belong to the genus Toxocara and exist in the intestines of the host, where they can grow to several inches in length. Roundworms are especially concerning in young animals, as they can lead to significant nutritional deficiencies, stunted growth, and other health issues due to their ability to consume nutrients that the host requires.

Roundworms are transmitted through ingesting larvae from contaminated environments, feces, or through the mother’s milk to puppies and kittens. Their life cycle can also involve eggs that can survive in the environment for extended periods, increasing the exposure risk for young pets.

While other parasites like coccidia, whipworms, and tapeworms can also infect the intestines, roundworms are particularly prevalent and are one of the first concerns veterinarians have when dealing with intestinal parasites in dogs and cats, making this choice the most appropriate answer.