Dogs and cats become infected with hookworms by ingesting infective larvae in soil or vegetation contaminated by feces containing the larvae. The worms can also penetrate the pet’s skin then migrate through the tissues of the gut. The majority of the larvae mature to adults within the digestive tract where they attach themselves with sharp teeth and suck large amounts of blood. Two weeks after ingestion, or four weeks after skin penetration, the adult hookworms begin to produce large amounts of eggs that are excreted with the feces. Within one week, the eggs develop into infective larvae.
When larvae have infected an animal, it can mature to an adult in the gut, migrate through tissues, or encyst themselves in skeletal muscles (become dormant). These cysts can be reactivated by pregnancy hormones and other stimulus. During the pregnancy, the reactivated larvae can travel to the mammary glands then become ingested by nursing puppies and kittens.
Hookworm larvae can infect humans as well by either penetration of the skin or ingestion of larvae-contaminated dirt and vegetables.
Dogs and cats become infected with roundworms by ingesting infective larvae in soil or vegetation contaminated by feces containing the larvae. Intermediate hosts such as rabbits or rodents infected with roundworms can transfer the worms and their eggs to pets if eaten. When larvae have infected an animal, it can mature to an adult in the intestines or encyst themselves in skeletal muscles (become dormant). These cysts can be reactivated by pregnancy hormones and other stimulus. During the pregnancy, the reactivated larvae can travel through the placenta into the lungs of the developing fetuses or to the mammary glands then become ingested by nursing puppies and kittens.
Each mature roundworm female can produce 200,000 eggs per day. These eggs are carried out with feces and can live within soil for many years. Humans can ingest roundworms via contaminated soils, fruits or vegetables.
Flea larvae serve as intermediate hosts for tapeworms by ingesting eggs on feces, bedding or soil. The eggs hatch and develop to cysticercoids within 1-2 days of the flea reaching the adult state. If a flea containing a cysticercoid is ingested by a dog or cat, that animal becomes infected and the tapeworm matures inside the dog or cat’s intestines. The tapeworms then begin producing many eggs. The eggs and/or segments of the tapeworms are passed with feces. Humans can become intermediate hosts if a flea is ingested, or if a dog licks their mouth after crushing a flea containing the cysticercoids.
Dogs or cats ingest infective eggs from soil or vegetation that has been contaminated by feces. The larvae hatch from the eggs after they are swallowed. When the larvae reach the cecum, they remain for one to three months until mature. Mature whipworms live and feed in the large intestine. Eggs are passed with feces and are very resistant to environmental conditions. Larvae develop inside the eggs to an infective stage after about one month. A human can ingest whipworm eggs from eating contaminated vegetation or soil.