Tapeworms in Cats & Dogs: Symptoms & Treatments

How your pet might pick up tapeworms depends on the species they’re prone to. Most tapeworms require two separate hosts to complete their life cycle:

For example, Dipylidium caninum is the most common tapeworm species in cats and dogs. They are transmitted through fleas (their intermediate host). The immature tapeworm eggs live inside fleas, which are commonly ingested by pets who groom themselves during a flea infestation.  

This is why ensuring you treat your pet for fleas is an essential step in any worming routine.  

Below, we explore the places where pets can pick up each type of tapeworm and whether or not they’re zoonotic (transferable to humans). 

There are multiple taenia species, but the risk of your pet becoming infected depends on the parasite’s intermediate host and your pet’s access to it. The key tapeworms in the Taenia species include: 

The definitive hosts for these worms tend to be humans and dogs, but some can infect cats as well.  

The intermediate hosts for each of these worms vary, with some infecting livestock (such as cows, sheep, and pigs) while others focus on wildlife (such as rats, mice, rabbits, and deer). The intermediate hosts pick up the eggs from eating infected vegetation in their environment, where they can survive for months without a host. 

Once inside the intermediate host, the eggs hatch in the intestines before moving to the striated muscles to develop, where they can survive for years. 

Humans or pets become infected with this worm when they consume the infected meat or organs (depending on the worm). Once they reach the small intestine, the immature worm will grow into its mature life stage and begin its life cycle again. Depending on the type of Taenia tapeworm, the parasite can reach 2 – 7 meters in length.  

Pets that live on farms or are frequent hunters of wildlife are most at risk of becoming infected with these types of worms. Taenia tapeworms are also zoonotic, and humans who eat raw or undercooked infected meat are also at risk of infection.  

Echinococcus granulosus, also known as the dog tapeworm or hydatid worm, typically uses sheep as its intermediate host as it consumes the eggs released into the environment.  

The eggs of the Echinococcus granulosus hatch in the small intestines of the intermediate host. They then penetrate the animal’s intestinal wall and move through the bloodstream to various organs (particularly the liver and lungs) where they develop into a thick-walled cyst that continues to grow.  

Pets (and humans) become infected by consuming the cyst-containing organs. The immature worms then make their way to the definitive host's small intestines, where they mature into adult tapeworms within 32 – 80 days.  

This type of tapeworm typically only impacts animals in Wales, those along the Welsh borders, and those in the Hebrides. But it is zoonotic and may cause Hydatid Disease in humans.  

The Echinococcus multilocularis is a species of tapeworm that typically affects canids (dogs, foxes, etc) as their definitive host. The intermediate host is often rodents which become infested by ingesting the eggs in the environment.  

Dogs and foxes are the most common definitive hosts for this species of tapeworm. Wild foxes will consume the flesh of an infected rodent, allowing the immature worms to make their way into the fox’s small intestine, where they mature and restart the life cycle.  

Dogs can pick up Echinococcus multilocularis either by consuming the infected rodent, becoming infected by eating the faeces of an infected fox, or grooming themselves after rolling the fox poo.  

This type of tapeworm is zoonotic (can be transmitted from pets to people). If the Echinococcus multilocularis is accidentally consumed by a human, it could cause a condition called alveolar echinococcosis, which can be fatal if left untreated and rarely displays symptoms.