Worrisome Worms

Posted on by Christopher Bern, DVM

One of the most common things that we see in pets is intestinal parasites. Most puppies and kittens have them due to being passed from the mother through the placenta or the milk. But it’s also not uncommon to see them in adult pets, especially those who spend much time outside or are not on heartworm prevention (more on that in a moment). The question that often comes up is “how do you prevent or get rid of them?” I hope to address that today.

There are three important principles to keep in mind regarding intestinal worms.

  1. Some of them are zoonotic, meaning that they have the potential of being transmitted to people. This happens most commonly in younger children due to their tendency to put their hands anywhere and then in their mouths. Worms can migrate out of the intestines and cause serious problems elsewhere in the body, so we need to keep our pets properly dewormed to help prevent illness in the human family.
  2. There is no one single deworming medication that will get every parasite. You need to identify the specific organism and then give medication appropriate to that worm in order to kill it. If you give an over-the-counter dewormer, you have a chance of not treating the right parasite.
  3. Most worms are not visible in the stool, even if they have them, so it’s important to have a vet examine a stool sample under the microscope for the proper identification. However, even the best sample can miss worms 10-20% of the time, so it’s not foolproof. Even I can’t automatically tell whether or not a pet has worms or which kind they are just by doing a physical exam.

Let’s briefly look at the most common intestinal worms.

Roundworms are long, spaghetti-like worms and arguably the most common we see. If a dog has a high number of them, they may vomit some of them or have them come out in the stool. But the most common symptom is simply diarrhea, so a fecal exam is necessary in most cases. Other symptoms include a thin body condition and a distended abdomen. These are zoonotic parasites, through a “fecal-oral” route (you have to touch an area with eggs and then touch food or your mouth).

Another common parasite, hookworms are normally too small to easily see in feces, even if they’re passing out. This kind of worm drinks blood from the intestinal lining and can cause life-threatening anemia in very young or small pets. It is also zoonotic, but besides the fecal-oral route, the larvae can migrate through the skin from infected soil, meaning that an infested yard could be dangerous to people walking bare-foot.

Whipworms are often difficult to find in a stool sample and normally can’t be seen in feces. The most common symptom is persistent diarrhea and weight loss that doesn’t respond to other therapies. It may take several fecal samples before these worms are identified, but thankfully they are not considered zoonotic.

Tapeworms are the worm that sort of breaks the rules. Because they reproduce by releasing entire body segments rather than individual eggs, it is hard to find them on a microscopic fecal exam. However, the segments are easily seen in the feces, on a pet’s rectal area, or anywhere they have laid down. When fresh, the segments are white, flat, and mobile, measuring about an inch long. As they age outside of the body they shrink and turn an off-white to tan color, resembling grains of rice. This worm can be zoonotic if the segments are swallowed.* Though normally not considered life-threatening, they can cause weight loss and malnutrition by absorbing nutrients from the intestinal tract. The most common route of transmission is from swallowing fleas (a problem in flea-infested pets), though some rodents can also carry them (a concern for cats that hunt mice and other rodents). Because of the necessary intermediate hosts, good flea control will also help prevent tapeworms.

If you didn’t already know, all heartworm preventions will also prevent some types of intestinal parasites in addition to the heartworms. Most of them only cover roundworms and hookworms, but Interceptor and Trifexis will also protect against whipworms. If an adult pet is positive for one of these worms, it’s usually the case that they are not on heartworm prevention, or need a different type (if it’s a whipworm infection).

Another important method of prevention is keeping feces picked up and keeping the soil dry and sunny. Worm eggs thrive in dark, moist areas, so parts of the yard with mulch and heavy shade can allow them to live for longer than in sunny areas. Most worms need time to develop into an infective state, so removing feces from the yard multiple times each week is very helpful. 

As I said before, there is no single dewormer that will treat or prevent all of these worms. You can use medications that will get up to three of them, but not all of them. Additionally, there are single-celled parasites (coccidia, giardia, clostridium, etc.) that can cause similar symptoms and aren’t affected by most dewormers. To keep your pet in good health and to protect the rest of your family, it is important to get regular fecal exams on your pets and keep them on regular preventatives.

*Gross trivia of the day… Around the beginning of the 20th century tapeworm segments were sold as diet aids to humans, reducing weight by having the tapeworms absorb the person’s nutrients.

About Christopher Bern, DVM

Dr. Bern has been with the practice since 1999 and currently works as the Chief of Staff for the Woodstock, GA hospital. View all posts by Christopher Bern, DVM →

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