Visiting Veterinarian : Parasite control
Little Pal, a terrier mix, arrived recently from down South. "Cute puppy," I commented, perusing the pile of papers the breeder had given the new owner. It included a list of vaccinations and worming medications already administered and a schedule of what to do next.
Let's pause for a grammar tidbit, because language is fun. Some words can be used as both nouns and verbs in such a way that the verb means the action of removing the noun. For example, to pit a cherry is to remove the pit. When you weed the garden, you remove the weeds (unless you're Amelia Bedelia). To add to the fun, with some of these words, add the prefix "de" and it still means the same thing. You can bone a chicken or you can debone it. Same dinner. What's this got to do with Pal? It's all about worming - or, if you prefer, deworming. Either term is acceptable and means the administration of medication to remove the worms from the puppy.
Pal's dad had dutifully brought a fecal sample for his introductory visit. A common misconception is that worms are usually visible in the feces. Not. Most worms that infect dogs stay happily in the gut, never seeing light of day. They do, however, lay microscopic eggs. Using special concentrating techniques, veterinarians test for these eggs, which alert us to roundworms, hookworms, or whipworms hiding inside. Sure, Pal may occasionally barf a pile of roundworms (which look like spaghetti) or pass worms in the stool, but this is uncommon.
Just because you don't see worms doesn't mean Pal is parasite-free. Tapeworms have a different modus operandi and are the one worm we do usually rely on owners to observe. The adult tapeworm stays attached to the lining of Pal's gut but sporadically releases flat rectangular segments which are actually packets of eggs. Visible to the naked eye, these segments may squirm about when fresh, then dry to look like grains of rice. Segments may be found clinging to the fur around the anus, in the feces, or on Pal's bedding.
"The breeder gave Pal several wormers," I remarked, wondering if I would be wasting the owner's money running a fecal so soon after medication. The test depends on the presence of adult female worms in the gut laying eggs. Most wormers kill adult worms, but may not get the juveniles.
Standard procedure is to wait a month or so after treatment before retesting a fecal. This gives any remaining juveniles time to mature and begin laying eggs. "He passed a bunch of worms right after we got him," his owner offered. "The breeder said that was probably from the last worming."
I nodded, ruminating. Toss the sample and wait a month before retesting? Or run this one just to be sure? I didn't know the breeder. Dogs from the South have a high incidence of parasitism due to the warm climate. And none of the breeder's medications addressed the possibility of protozoal organisms that can also infect Pal's gastrointestinal tract. We ran the sample. "He's got hookworms," I informed Pal's dad later that day. "Also a protozoal parasite called coccidia."
Why hadn't the breeder's treatments eliminated these parasites? The coccidia were probably never diagnosed, since there was no record of the breeder having an actual fecal specimen tested. Treating protozoa like coccidia requires an entirely different class of drugs than intestinal worms. "I've got medication made up to treat the coccidia," I said.
But what about those hookworms? The wormers already used should have taken care of them. What happened? Maybe the dose was incorrect. More likely, Pal had been continuously reinfected from the environment. Hookworms, like most intestinal worms, are transmitted primarily by fecal-oral contamination. Fecal matter can disperse into the soil leaving a clean-looking environment, but worm eggs persist. Pal plays in the yard, comes in, licks his muddy paws, and voila! Worms!
One of the breeder's many handouts suggested that monthly heartworm preventive pills would take care of any remaining worms. This is only partially correct. Different types of heartworm preventive have different effects on different worms. For example, Heartgard Plus ® contains ivermectin and pyrantel, and is labeled "to treat and control ascarid and hookworm infections." (Ascarids are roundworms.) Notice the label makes no mention of whipworms.
Interceptor ®, on the other hand, contains milbemycin and is labeled "to control adult hookworm infection, and remove and control adult roundworm and whipworms. This technical wording can be unintentionally misleading. It does not say "remove adult hookworms." It says "control."
We're back to examining the vagaries (and legalities) of language. In order to be labeled with the term "remove," a single dose of product much cause greater than 90 percent reduction in adult worms. Interceptor misses that mark with hookworms. If you continue to give it month after month, it will eventually eliminate that 90 percent of adults. That's why they can legally say it "controls" adult hookworm infection.
But we don't want to leave 10 percent of those bloodsucking hookworms lingering inside Pal for a month until the next dose of heartworm medication. No way. We're gonna dispense additional wormers today and try to knock those suckers out. So, as you can see, relying on heartworm preventive as a blanket treatment for all types of intestinal worms is not adequate. "Good thing we ran the test," I thought. We prescribed wormer for hooks and sulfa drugs for coccidia, instructing his owner to clean all feces from the environment every day. We will repeat the hookworm medication in two weeks and recheck fecal samples based on the life cycle of each organism.
Intestinal parasitism is a serious problem. Left untreated it can lead to significant consequences, including severe or bloody diarrhea, intestinal blockages, anemia, poor nutrient absorption, and weight loss. Roundworms and hookworms can also infect people, with children being at the greatest risk.
Whether your vet calls it worming or deworming, it's the right thing to do. Bring those stool specimens and help keep your pals parasite-free.