Tapeworms are the largest of the four most common intestinal parasites, which also include roundworms, hookworms, and whipworms. These flat white worms are made up of multiple small segments, with adults typically growing to 4 to 8 inches in length, though some species can grow considerably longer.
If your service dog becomes infected with tapeworms, they latch on to her intestinal lining with hook-like parts. They feed on partially digested food as it passes—not on their host’s blood like many other parasites. While tapeworm infections generally don’t cause serious problems (they’re more likely to do so in young puppies), heavy infections can cause discomfort and other effects that interfere with your assistance dog’s ability to carry out her important tasks.
How Dogs Contract Tapeworms
Dogs pick up most intestinal worms by directly ingesting eggs or larvae, but things work differently with tapeworms. These parasites require what’s known as an intermediate host—in the case of the most common type of tapeworm affecting dogs (Dipylidium caninum), it’s a flea—to complete its lifecycle; other types, including Taenia and Echinococcus species, use rodents or other mammals.
Tapeworm segments contain their own reproductive organs. As a tapeworm grows in its final host, segments break off and pass via the stool. When the segments die and dry out, they break open and release their eggs into the environment. Flea larvae eat the eggs and the tapeworm begins developing in the flea. When a dog ingests an infected flea, usually during grooming or when biting at the flea, the tapeworm is released into the dog’s intestine when the flea is digested.
Tapeworms can pass to humans, but still require the intermediate host, which must be ingested by the person. So, while it can (and does sometimes) happen, it’s not likely or common. Kids are most at risk.
Symptoms and Complications of Tapeworm Infections
Tapeworm infections don’t typically cause symptoms in adult dogs, though heavy infections can cause some digestive discomfort, increased hunger, unexplained weight loss, or nutritional deficiencies if left untreated over time. Puppies are far more vulnerable to anemia, stunted growth, intestinal blockages, and other complications.
There is, however, a common sign: tapeworm segments around your dog’s anus, in her feces, or on her bedding. Segments are visible to the naked eye, and are white or off-white and resemble pieces of uncooked rice or cucumber seeds. They move around at first, but once they die they become hard and more yellow in appearance. Your assistance dog may scoot her backside along the floor if irritating segments are stuck to her (but keep in mind this can be a sign of other problems, including an infected anal sac). If she ingests dead segments, it can cause vomiting.
Diagnosis and Treatment of Tapeworms
Your veterinarian can diagnose the infection in your service dog by finding tapeworm segments or eggs in a stool sample (or by seeing tapeworm segments around your dog’s anus). Sometimes, more than one sample is needed, as evidence isn’t expelled with every bowel movement.
Treatment is simple, safe (rarely causing side effects), and highly effective. A parasiticide is administered orally or by injection. Epsiprantel, fenbendazole, and praziquantel are commonly used de-worming agents. They allow the tapeworms to dissolve in the dog’s stomach acid, so don’t expect to see the dead worms come out. Your vet will prescribe a product and might recommend a follow-up dose about two weeks later to be thorough. However, tapeworm medications are very effective, and additional tapeworms are usually due to re-infection from other fleas.
Preventing Tapeworm Infections in Your Assistance Dog
Tapeworms are only contracted via an intermediate host, so keeping your dog away from them is the best protection against an infection. Since fleas are the source of the most common canine tapeworm in the US, ask your vet about a medication for regular flea control. You have lots of options, including various types of topical applications and collars.
Small rodents can be a source of intestinal worms, though not often tapeworms in the US. Other small creatures like birds and roaches also pose risks of other types of internal parasites. Keep your service dog away from mice and other small animals and arrange for pest control if you develop a problem in your home.
It’s generally suggested that adult dogs take a regular heartworm preventative, and many of these are also effective at killing tapeworms. Talk to your vet about a product and administration schedule.