Gazette Vet: My Dog Has… Worms!


by John Andersen, DVM

If there’s one thing I see a lot of as a small animal veterinarian, it’s diarrhea. It has always held true that the two most common causes of diarrhea in dogs and cats are parasites and diet. So when my own 10-month-old Labrador Retriever woke us up at 1 a.m. last week to go outside and then had repeated bouts of diarrhea, we figured he must have eaten something he shouldn’t have.

It was a rough night for everyone, with bathroom requests about every hour (in 30 degree windy weather, of course). We treated him with a bland diet and some medication, but after a few days of improvement, he was still having loose stools. So I figured I would at least bring a fecal sample into work, just to rule out intestinal parasites of course. I mean, I’m a veterinarian, my dog is really well cared for, he couldn’t have worms, right?

It was certainly my surprise when the veterinary technician who read the fecal exam said “ummm, Dr. Andersen, your dog is loaded with roundworms…and a few whipworms too…and some coccidia too!”

Of course the other veterinarians and just about all the staff gathered around to take a look at my dog’s fully loaded microscope slide and had a good laugh at my expense. But it was actually a really good lesson on just how common intestinal parasites are, even in spoiled pets.

There are basically four types of intestinal worms we see in dogs (three in cats): roundworms, hookworms, whipworms, and tapeworms. All are disgusting to think about, and all can cause diarrhea, weight loss and other related problems. Heartworms, by the way, live inside of the heart and ringworm is actually a skin fungus, just in case anyone was wondering.

Intestinal parasites generally have a fecal-oral route of transmission–the adult worms live in the host’s intestine and produce eggs which are passed in the stool (it is these eggs they we detect on a fecal test). One way or another, a new dog or cat comes along and ingests these eggs and, voila–intestinal parasites! Did I mention that roundworms and hookworms can spread to people, mostly children?

I’m pretty certain my dog acquired his worms right here in Crozet by eating fox or coyote poop. We frequent the fields in Old Trail and the trails around Mint Springs park and we know it’s just a fact of life that he’s going to find some wildlife poop to eat–can you blame him? Foxes and coyotes are in the canine family and get most of the parasites that domestic dogs get. Unfortunately, their bathroom is my dog’s playroom and whipworm eggs are stable in the environment for years (as are hookworm eggs). So, really, intestinal parasite exposure is just part of having a good dog’s life. But we still love him, worms and all.

Many of our clients ask us if it’s really necessary to spend money on a fecal test on their dog who seems perfectly fine. If their dog’s poop is solid and they’ve never seen worms in it, they shouldn’t have anything to worry about, right? Unfortunately, the most common clinical sign of a healthy adult animal with worms is…nothing. That’s right, their immune system often helps to keep the worm numbers low and if their intestinal health is otherwise good, there may be no diarrhea, initially anyway. If clinical signs are present, they are usually intermittent soft stool, bad gas, and weight loss/thin body condition.

It is important to note that worms are almost never seen in the stool of adult animals, as they are perfectly happy staying put inside the intestines. Also, intermittent soft stool is easily missed if you have a fenced yard or have a dog who spends a lot of time off-leash. It’s usually not until the worm burden hits a certain point that they start to have bad, urgent diarrhea. I certainly wonder how long my poor dog had had parasites before I finally found them.

Fortunately, worms are generally pretty easy to treat with the appropriate dewormer. Some animals, however, can have some secondary inflammatory bowel problems that may warrant additional medications.

How can you prevent your dog from getting worms in the first place? Generally, keeping them on monthly heartworm prevention is the best thing you can do because most heartworm preventatives are also good intestinal parasite preventatives. I will often tell people that although heartworms are a disaster for a dog to get, the more significant benefit from keeping them on monthly heartworm prevention is keeping intestinal parasites away. Intestinal parasite prevention is also an important reason to keep dogs on heartworm prevention year round–those whipworm and hookworm eggs are just as potent in the middle of the winter and, as far as I know, foxes and coyotes still go #2 when it’s cold outside!

But nothing is 100 percent. My dog has been on monthly prevention since we got him as a puppy. But if they are getting heavily exposed or possibly have local immune system issues, the preventatives may just not be enough.

So, keep your dog (and outdoor cat) on a monthly preventative and make sure you get their poop examined at least once a year. And don’t worry, Crozet, I always pick up my dog’s poop, I hope you do, too!