Click on the image for an explaination or
Read more about the fleas that bring common tapeworms to pets here
Tapeworm parasites are quite a common in dogs and cats. Luckily, the symptoms they cause are not severe and your veterinarian has excellent ways to help you eliminate them.
Unlike the other common intestinal worm of pets, like roundworms and hookworms, tapeworms require two different types of animals (hosts) to complete their complicated life cycle. One (the intermediate host) does no more than carry the parasite around to a new home. The second type of animal (the final host ie, your pet) is the one in which the tapeworm can mature in the intestine and develop its eggs. Fleas are the intermediate host of the most common tapeworm of pets, Dipylidium caninum, and dogs and cats are its final host. There are other, less common tapeworms, there is a bit about them at the end of this article.
Tapeworms do not have a mouth. They feed through their skin (cuticle). All tapeworms are segmented – like a long string of pearls. Some are many feet long, other types, only a few segments long. The common tapeworm, Dipylidium is about 12-18 inches long when it is mature. You can click on the link next to the picture at the top of this page or here to expand it and see the tapeworm and its life cycle close up.
Every tapeworm has an oval head (scolex) to which are attached a group of hooks – similar to fish hooks (its rostellum). These hooks anchor the tapeworm to the lining of the pet’s small intestine. Only the last pearls break off and leave the body when they are ripe (gravid) with, or after, a bowl movement. The telltale segments are generally found on the stool – not in it.
These pearls (proglottids) are really an egg case. They are filled with thousands of individual tapeworm eggs. When the egg case breaks open, these eggs are scattered about in hopes that a larval flea will eat one by accident. In the flea larva, the tapeworm egg hatches, forms a cyst and waits. Eventually, the original pet, or a new one, may eat some of these fleas and the parasite’s life cycle repeats. This can occur again and again.
There are many kinds of tapeworm. But over 98% of the pets I see are infested with a tapeworm called Dipylidium caninum or the cucumber `tapeworm. This was not always the case and is still not the case in other less developed parts of the World as well as in rural areas where dogs run free - particularly if the hunt or eat rabbits. (ref) A particularly dangerous one, Echinococcus, also passed to dogs through raw meat.
But back to the common tapeworm, Dipylidium, that is probably the one you are dealing with: The off-white grains of rice or sesame seed-sized granules you see surrounding your pet’s butt or on its stool are the egg cases (proglotid segments) of this parasite. They often writhe or flex slowly until they dry. Many of my clients think that these segments are the whole tapeworm, but they are really only the last few ripe segments of the tapeworm’s long body.
When the Dipylidium segments dry on your pet’s coat, they shower its fur with hundreds of eggs. Then, fleas that are present on the pet or in its environment ingest (eat) these eggs. In the flea, the new tapeworm (cysticercoid) develops. Then, when the pet catches and eats a flea while grooming a new tapeworm develops in the pet’s intestine.
There is nothing that looks quite like a tapeworm segment. Once or twice, I have been fooled by bits and pieces of grizzle in a dog’s stool but the segments are very distinctive. One could mistake fly maggots contaminating stale feces for tapeworm segments if one did not examine them closely. (tapeworm segments are flatter than fly maggots) The best thing to do is to pick them off of the pet with a long, fine stick, place them on a wet paper towel in some container and bring them to your veterinarian for confirmation. If there is any doubt, the veterinarian will tease the parasite apart under a microscope and look for its distinctive egg packets.
Occasionally, after a bout of diarrhea, long strings of segments are passed still connected and intact. That was the ancient way of ridding the body of tapeworms, but it was very difficult to get the head of the tapeworm to be expelled. If the head did not pass out, the tapeworm just re-grew. There are still internet outlets peddling these medications. They are all quite dangerous. If they can cause a severe enough diarrhea to expel tapeworm scolexes (the heads) they have to potential to cause intussusceptions , volvulus and anal prolapse as well.
Dogs and cats rarely if ever become ill from tapeworms. So signs of ill health, weight loss, diarrhea, scooting or vomiting are usually do to some other problems.
Some, long nosed pets are very efficient at snapping up a flea in an instant - before you ever notice it. Much like head lice on your kids, you rarely ever know.
These particular tapeworms are vile and disgusting, but they are not dangerous to your pet’s health in the numbers that they usually occur. It is common for newly arrived stray kittens and puppies to have diarrhea, vomiting and tapeworms. But the diarrhea and vomiting is probably not due to the tapeworms. It is just that the unsanitary conditions that allowed the tapeworms allowed various other diseases to occur.
Tapeworm segments are only passed intermittently, so there may not be any on the surface of the stool sample you bring in or the one your vet collects at the office. When they are there, these segments are on the surface of the feces, not mixed within it. So when your veterinarian examines the stool microscopically, it is rare for him/her to identify tapeworm eggs even if the pet is infected. When you can’t bring in a well-preserved tapeworm segment you find at home or when your vet cant find any when he examines your pet but you saw things that look like the things in my illustration – just assume the pet has tapeworms. Luckily, the medication that removes them is quite safe.
Not all pets in a household with tapeworms always have them. There are usually certain pets that are more efficient in catching fleas. Those are the pets that are more likely to get tapeworms. Not all veterinarians suggest that all the pets in the household be treated; but I generally do. That is because it is quite common to miss one infected pet in a multi-pet household, only to see the tapeworms return a month or so after treating only the one(s) on which tapeworm segments were seen. In really frustrating, persistent, recurrent infections, I always ask about the neighbors pets. If your neighbor’s chainlike fenced yard is adjacent to yours and his pets have tapeworms, they will get to your pets eventually. I often offer to worm the neighbors pets at reduced cost just to coax them in, or have the concerned owner supply them with medication. (That has to be done tactfully)
The most common tapeworm-specific medicine used in the USA is praziquantel. Fenbendazole (Panacur) will kill certain tapeworms, but it is not very effective against the common tapeworm of pets. Many pet owners assume, incorrectly, that the Hartz Once-A-Month wormer and products like it will kill tapeworms. It will not. You must use a medication that lists praziquantel as the active ingredient. I never suggest that pet owners act as their own veterinarians – it is rarely a good idea. When the tapeworms have been killed, you will not see them pass out in the stool. They will simply be dissolved by the pet’s digestive enzymes.
You either gave a medication that was not designed to kill Dipylidium tapeworms, you gave it in the wrong amount, tapeworms were not what you saw or your pet became re-infected because fleas were still present.
I have never known praziquantel, given in the correct dose, to fail to kill all the tapeworms. The most common reason for failure is that you were not successful in ridding your pet of all fleas. The second most common reason is that one of your other pets that was not treated is carrying the parasite. (It would still have required fleas to transmit it) There are monthly heartworm medications that also contain praziquantel. Those are the best solution for stubborn cases. This is one.
product to eliminate fleas are monthly selamectin
topical drops. I prefer topical to oral products. But effective oral products exist too. Read about them here. There are other effective ones, but fleas in
my area of the Southern USA have become resistant to many of them.
It may take a few months to sop up all the fleas in your pet’s environment, particularly if stray pets visit your premises or your pets are out and about.
If, for a single instant, there are no fleas and no adult tapeworms, the problem is solved – at least for now. If you don’t eliminate all mature fleas, within a month or so the tapeworms return. Some pets in a contaminated household may remain free of tapeworms. These are pets with “smushed” faces such as Persian cats or pug-like dogs, which cannot catch fleas.
Veterinarians like to please their clients. They are never happy when pet owners return telling them that their pet still has tapeworms. The vet knows that the reason they still have tapeworms is that the owners were not successful in eliminating fleas from their pet’s environment - but they may not tell you that. Instead, they have found that repeated injections or oral tapeworm medications are more likely to break the re-infection cycle. If you have absolutely no fleas in your pet’s life, and give it a single praziquantel injection or tablet, the tapeworms are gone. But that is easier said than done. Giving a second injection also gives you more time to battle the fleas successfully.
It does occasionally
happen. When it does, it means a flea got eaten by a human – usually
a child. I have never had this happen in a client’s family, but
I am told it does occur. Fleas are small, fleas hop and I do not suppose
there is much taste to a flea.
You can read about that potential problem here.