Parasites That Cause Weight Loss in Cats

Weight loss is a common symptom of some feline parasitic infections
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It is not unusual for a cat owner to wonder if their pet has parasites. According to the Cornell University College of Veterinary Medicine as many as 45 percent of cats are afflicted with gastrointestinal parasites. If you notice your kitty is suffering from unexplained weight loss, parasites might be the culprit. Schedule a visit with your veterinarian to rule out the presence of parasites, such as hookworms, stomach worms, and Giardia.


Hookworms are strange looking creatures with skinny, thread-like bodies that live in the intestines of cats. Cats become infected either by eating the worms, or after the worms penetrate their skin. Hookworms attach to the walls of the intestines and cause blood loss that can lead to anemia. The symptoms that you might notice your kitty exhibiting are diarrhea and weight loss. Hookworms have an extraordinarily long life span and, if left untreated, they can live as long as your cat. Fortunately, hookworms are easy to diagnose and treated easily with medication.

Stomach Worms

Two species of stomach worms can affect cats: Ollanulus tricuspis and Physaloptera. Ollanulus infections are difficult to diagnose and treat, but luckily they also are very uncommon. Symptoms of this worm include chronic vomiting, loss of appetite, weight loss, and malnutrition. Physaloptera infections, while treated easily, also are uncommon. Symptoms of this parasite include vomiting, loss of appetite, and weight loss.


Giardia is an infection that most people are familiar with. It is a one-celled organism that spreads to cats through ingestion of cysts contained in contaminated food and water. Symptoms of Giardia include diarrhea, weight loss, dehydration, and lack of appetite. Detection and treatment are difficult, but not impossible. You might need to give kitty frequent baths during treatment to prevent reinfection.


As with any health concern involving a pet, consult with a veterinarian if your kitty experiences unexplained weight loss or if you suspect a parasite. Left untreated, parasitic infections can weaken a cat’s immune system and cause increased susceptibility to other diseases. Additionally, some parasites are transmissible to humans, so it is important to get rid of the parasites to protect the health of people who come into contact with your cat.

Always check with your veterinarian before changing your pet’s diet, medication, or physical activity routines. This information is not a substitute for a vet’s opinion.

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