Ewwww, Gross!

Even though I loved my professor, ( Dr. Hendrix, who interviewed me and called at 6 am one morning to inform me I had FINALLY been accepted after applying to that particular school, Auburn, 3 years in a row) parasitology was one of my worst subjects in school. The internal and external "hitchhikers" on animals (and humans-ewww, gross!) are just nasty. Even though a veterinarian is supposed to love all creatures great and small, worms and fleas and mites are just out of luck as far as I am concerned.

We often get calls from worried owners when they find a worm in their pet's feces or in their bedding. I don't know why, but we tend to describe the way worms look in food terms. I suppose they are just familiar references. "Does the worm look like a spaghetti noodle, round and long, or like rice segments, short and flat?" "Does the thing in the bedding or on his hind end look like a little dried up sesame seed?" We generally recommend that the owner bring in a sample of the pet's feces if there is any doubt so we can test it and see for ourselves. Fecal testing involves centrifuging (spinning) and floating a sample in a solution to allow eggs of worms and other microscopic organisms such as coccidia and giardia, to rise to the top. We then draw a bit of this top fluid off the sample and examine it under the microscope. We also take a smear of the fecal matter and look at that directly, often finding things not evident on the spun sample. Eggs of tapeworms, for example, are often shed in "packets," too heavy to float in most standard solutions. We rely on visual identification of the wiggling "rice-like" segments or the dried up "sesame seeds." in the bedding to make a diagnosis.

Tapeworms (Dipylidium caninum) are an interesting (though still gross-I'm not going back on my original claim!) creature due to the stages of their life cycle. The adult worms live in the small intestine of the cat or dog. Theoretically, they can also infest humans, but they aren't zoonotic or contagious from the pet. They hook into the intestinal wall, but do not "suck" nutrition as do hookworms. Instead, they absorb nutrition through their "skin" as the food passes by the worm on its travels through the digestive tract of the infested animal. All the segments are hooked together, end-on-end, sometimes reaching over 6 inches. There is another species of tapeworms, (Taenia Hydatigena) that can grow up to 5 YARDS long! That is just not right.

As the worm matures, the end segments, which are really just the egg packets we described at this point, detach from the rest of the worm. These are passed in the feces and observant owners see them, bright white, glistening, wiggly "rice." These packets break down and release tiny eggs into the environment or on the animal, usually in the same vicinity where there are fleas going through their life cycles. Larval fleas will eat the flea "dirt" or dried blood passed by adult fleas, along with the tapeworm eggs. When a pet grooms itself or chews its fur because it is itchy, it will often ingest one or more of these infested fleas. Once inside the host animal, the young tapeworm is released, ready to attach to the small intestine and start the cycle all over again. There is no other way a pet (or human) can get the Diplidium tapeworm-it had to eat a flea. The less common Taenia tapeworm is contracted through eating prey animals or rotting carcasses.

Fortunately, the treatment for tapeworms is easy and safe. Praziquantel is the drug of choice, given as a single dose. It can be expensive, but what isn't these days? It is also essential that good flea control is implemented or the pet will immediately become reinfested. The drug rarely "fails." Much more likely is the pet clearing the current adult parasites, ingesting another flea, and starting the life cycle again. It takes 3 weeks for a tapeworm to go from being swallowed by the pet inside the flea to shedding segments in the feces (and thus being seen by the owner.) It is not necessary to deworm all of the pets in one household just because one has the segments-that is, unless you see the segments on each pet or on all of their bedding. We only give medication like dewormers to the animals that need it.

We like to save some of the really "good" parasites that people have brought to us over the years for identification-we have a "chamber of horrors" on an upper shelf that is really popular with the school tours when they come through. All together now, "Ewwwww, gross!"

Peace,
DrReneigh