Signs of Parasite Infection of Cats & Dogs

Parasites are organisms that live on a host animal such as a dog or cat. These microorganisms cause illness and disease within the host animal by taking nutrients without giving back anything beneficial. The signs and symptoms of parasitic infections of dogs and cats varies depending upon the infection, but some signs are common across all infections. Speak to a licensed veterinarian if you suspect your dog or cat has a parasitic infection.

  1. Diarrhea

    • The most common sign of an internal parasitic infection in cats and dogs is diarrhea, according to the "Clinical Textbook for Veterinary Technicians." Most internal parasites live in the digestive tract. When parasites attach, live and breed within the digestive tract, regular bowel movements are disrupted. Slightly less common, but still possible, is constipation. Constipation usually only occurs when a parasitic infection is prolific enough to obstruct the dog or cat's bowels, according to the "Clinical Veterinary Advisor."

    Change in Appetite

    • Dogs and cats experiencing a parasitic infection can lose their appetite, according to the "Clinical Veterinary Advisor." Loss of appetite may be directly related to the parasite or a secondary effect caused by fatigue. Other dogs and cats experiencing parasitic infections may experience an increased appetite. This is particularly true of intestinal parasites, which sap nutrients from the animal's body. Dogs and cats with an increased appetite due to parasitic infection attempt to compensate for the nutritional deficit from feeding the parasites, according to the "Clinical Textbook for Veterinary Technicians."

    Lethargy

    • Dogs and cats may experience lethargy when suffering from an infection. The level of lethargy depends on the animal's overall health, age, nutritional status and the severity of the infection. Pediatric and geriatric animals are more likely to experience high levels of lethargy. So are cats and dogs with a severe parasitic infestation, according to "Pathology and Parasitiology for Veterinary Technicians."

    Physical Appearance

    • Dogs and cats suffering from internal parasites will often experience a change in physical appearance. Rapid weight loss or weight gain are possible. Tapeworms can cause a rounded, pot-bellied appearance, according to the "Merck Veterinary Manual." The condition of the animal's fur or skin can deteriorate due to a lack of proper nutrients. External parasites, such as fleas and ticks, may cause rashes, sores and itching. Severe external parasitic infections in dogs and cats can cause sores and itching so severe that the animal has open wounds, as stated by "Shelter Medicine for Veterinarians and Staff."