Internal Parasites in Dogs and How to Treat Them
📝 Summary
Deworming isn't only for dogs that show worms in their stool — by then the body is already full of eggs. Common internal parasites include roundworms, tapeworms, hookworms, pinworms, heartworms, and toxoplasma, each with distinct symptoms and routes of spread; a vet confirms and prescribes the right treatment.
1 Roundworms
Puppies are more likely to be infected than adults, and it’s the most common parasitic disease in young dogs, mainly hitting them between three weeks and five months; severe cases can be fatal. Symptoms: gradual wasting, pale mucous membranes, poor nutrition, rough dull coat, poor appetite, vomiting, and worms seen in stool or vomit. Roundworms live in the small intestine and stomach, robbing the body of nutrients and releasing toxins.
2 Tapeworms
Tapeworms are made of segments; each dropped segment grows a new head that bites into the intestinal wall and extends backward into a long chain of about 120 segments. The segments gather near the anus and make it itch. If you see worm-like, wriggling bodies in the stool, it’s almost certainly a tapeworm. They spread via dog lice, fleas, and rats; heavy infection can cause intestinal blockage and anemia.
3 Hookworms
Hookworms peak in summer; their hooked heads bite the intestinal wall and feed on blood. Fecal tests show oval eggs. Severe infection brings loss of appetite or refusal to eat, vomiting, diarrhea, and the telltale sign of black, coffee-colored, or tarry stool. Pale membranes, wasting, dehydration, severe anemia, and even coma and death follow.
4 Pinworms
Also called threadworms, they hatch in the stomach and duodenum after infection and like to lay eggs near the anus, releasing dozens at a time. This irritates the skin around the anus and keeps the dog awake.
5 Heartworms
The dog heartworm (Dirofilaria immitis) is a pale-yellow, slender, thread-like worm. It spreads through mosquito bites: a mosquito draws in larvae, which become infectious after 10–48 days, and the bitten dog is then infected. Living in the heart, it damages it and gradually wears down the dog’s health; severe cases end in heart and lung failure, anemia, pulmonary edema, ascites, jaundice, and kidney or liver failure.
6 Toxoplasma
Toxoplasma needs no introduction — a worldwide zoonotic protozoan disease. It lives inside host cells; the cat is its definitive host and various animals are intermediate hosts. It breeds in the cat and passes oocysts in the feces, contaminating the environment. In infected dogs it destroys lymphoid and reticular tissue, leading to serious disease. Besides the digestive tract, it can enter through the eyes, nose, respiratory tract, skin, or even the embryo — which is why people say pregnant women shouldn’t be around cats and dogs. In reality, a person would have to eat fresh infected cat feces daily to catch it.
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