Common Internal Parasites in Pets: What You Need to Kno

Roundworms

Roundworms are parasites that primarily inhabit the small intestines and stomachs of pets. Under favorable external conditions, the eggs of these worms develop into infective stages. Once ingested by dogs, the larvae emerge in the intestines, burrow into the intestinal wall to mature, and then return to the intestinal lumen. After about three to four weeks, they grow into adult worms.

Common symptoms include vomiting, decreased appetite, weight loss, pale mucous membranes, and diarrhea. In severe cases, you may find worms in the vomit or feces.

Tapeworms

Tapeworms mainly reside in the small intestines of cats and dogs. There are various species, with the most common being the dog tapeworm (Dipylidium caninum) and the hydatid tapeworm (Echinococcus granulosus). Fleas and lice serve as intermediate hosts for the dog tapeworm, developing into cysticercoids within them. When cats and dogs are infested by these intermediate hosts, they become infected with tapeworms, which take about three weeks to mature into adults in the intestines. The larvae of the hydatid tapeworm, known as echinococci, can parasitize the livers, lungs, and other organs of various animals and humans. Dogs can become infected by consuming organs containing echinococci.

The primary symptoms are digestive disturbances.

Heartworms

Heartworm disease is a blood parasite transmitted through mosquito bites. It can infect dogs of any age and has also been found in cats and humans. Studies abroad have reported that up to 15% of stray cats are infected with heartworms. Due to their smaller hearts, cats have a higher mortality rate than dogs once infected. The intermediate hosts for heartworms in dogs include the Anopheles sinensis and Aedes albopictus mosquitoes. Dogs become infected after being bitten by mosquitoes carrying infective larvae. Adult heartworms reside in the right hearts and pulmonary arteries of cats, dogs, and humans, producing larvae (microfilariae) that circulate in the blood. When mosquitoes bite infected cats and dogs, they carry the larvae, which can then be transmitted to other cats, dogs, and humans through further mosquito bites. Dogs can be reinfected multiple times.

The primary symptoms are heart function damage, leading to systemic symptoms.

Hookworms

Canine hookworms parasitize the small intestines of dogs, particularly the duodenum, and can cause anemia and gastrointestinal dysfunction. The infection can occur through ingestion or skin penetration.

Giardia

Giardia is the culprit behind persistent diarrhea in cats and dogs. This microscopic parasite is not visible to the naked eye and requires laboratory testing for diagnosis. Infection occurs when the eggs of the parasite are ingested through feces or consumed from contaminated water sources.

Symptoms range from mild to severe diarrhea, with persistent or intermittent episodes.

Coccidia

Coccidia are also microscopic parasites that can cause coccidiosis, an illness caused by several species of coccidia that infect the intestinal mucosal epithelial cells of cats and dogs, primarily affecting young animals.

Primary symptoms include diarrhea, decreased appetite, anemia, and the presence of mucus and blood in the feces in young dogs. In adult cats and dogs, symptoms may include anorexia, constipation, and alternating diarrhea.

When going on outdoor trips, avoid letting pets drink untreated water or eat raw food. Adult cats and dogs should be dewormed every three months. If you notice symptoms like decreased appetite or diarrhea after returning from a trip, it's important to take your pet to a veterinarian for a checkup and treatment.