TAENIA SPECIES TAPEWORMS
Caption: Example of a Taenia Tapeworm (this one is a human species that comes from eating undercooked beef)
After gaining some pet owning experience, the average pet owner has heard of tapeworms transmitted by fleas and knows to watch for sesame seed-like segments around their pet's nether regions or on the surface of stools. In fact, there is a part two to this story as there is another type of tapeworm to which dogs and cats are vulnerable. These other worms are members of the Taenia genus.
There are several members of the Taenia genus with which one may come to be aquainted:
To keep things simple, we will stick to the term Taenia to refer to all them. There are, as you might guess, other Taenia species that infect animals other than dogs and cats but we will leave them out of this discussion for simplicity.
THE TAENIA LIFE CYCLE
The life cycle of Taenia tapeworms starts in the host’s intestine, the host being a dog or cat. The worm can be unbelievably long (up to 5 yards for Taenia hydatigena) and is made of segments. Each segment contains an independent set of organs with new segments being created at the neck and older segments dropping off the tail. As segments mature the reproductive tract of the segment becomes more and more prominent until it consists of a bag of tapeworm eggs. These segments, called “proglottids” are passed with the feces into the world where an unsuspecting intermediate host (mouse, rabbit, deer, sheep etc.) swallows one while feeding.
The young tapeworm hatches in the new host’s intestine and escapes into the blood supply with the next stop being the liver. (Remember, this new host is a prey animal such as a mouse, rabbit, deer etc. We have not gotten to the dog or cat predator yet). The larval tapeworm wanders through the liver, leaving bloody tracks behind it and ultimately falls into the abdominal cavity where it forms a sac and waits. After about 2 months of development in this location, the larval tapeworm is ready to continue its development but it will need a new host to do so. When the host dies or is killed a predator, the sac and its young tapeworm inside may be consumed accidentally.
About 2 months later, inside the predator, the young tapeworm is now mature and is beginning to shed its first segments and the cycle begins again.
HOW DO YOU KNOW WHAT KIND OF TAPEWORM THE SEGMENTS ARE FROM?
The tapeworm on the right is a member of the Taenia genus while Dipylidium is on the left.
In most cases, tapeworm segments seen are from Dipylidium caninum, which is not called “the common tapeworm” for nothing (i.e. it is very common). The segments of Dipylidium are longer than they are wide and are said to look like grains of rice. The segments of a Taenia tapeworm are wider than they are long.
IS IT IMPORTANT TO RECOGNIZE WHICH TYPE OF TAPEWORM IS PRESENT?
The good news here is that the same medication, Praziquantel, kills both types of tapeworms efficiently. Where it becomes useful to know one type of worm from another is when it comes to prevention. Dipylidium comes from swallowing a flea; Taenia comes from swallowing carrion or hunting prey.
For more information about Praziquantel click here.
For more information about Dipylidium caninum click here.
Tapeworms do not cause significant symptoms
If you see tapeworm segments on your pet’s fur or feces,
Page last updated: 7/30/2019