Internal parasites in dogs and dog grooming

Bet you didn’t know these two things were related, now did you? Read on to find out why this is important for your dog groomer to know when your dog has internal parasites and how a groomer can help alert you to a problem. 

Internal parasites may not seem like a topic that would concern your dog groomer, but like so many other dog health concerns, it certainly is. Why? Because a healthy dog on the inside reflects on the outside. This topic isn’t for the faint of heart,  but it’s an important one that needs to be discussed. Let’s start by talking about what internal parasites in dogs are. 

Infographic of the life cycle of intestinal parasites. Picture is of a dog with information on how a dog gets parasites and how they then develop into a problem
The life cycle of intestinal parasites in dogs. Original can be found here.

Definition of internal parasites in dogs

According to the CDC, a parasite is an organism that lives on or in a host (rent-free, mind you!) and gets its nutrition either from the host or at the expense of the host. In other words, they are very unwelcome guests living in or on your dog. 

An internal parasite would be one that lives inside of your dog as opposed to external parasites like fleas or ticks. 

How dogs become infected with internal parasites

It’s easier than you may think for a dog to become infected with internal parasites. Some dogs are unfortunate to be born with internal parasites they get from their mother or the parasites are passed on through the mother’s milk. 

Often dogs contract internal parasites when they unknowingly eat eggs or spores which can be found in contaminated soil, food, water, feces, or eating an infected animal that your dog may have caught. Some parasites are passed on from infected fleas or mosquitos. 

Hookworms can burrow their way through your dog’s skin and lay eggs (you were warned that this isn’t for the faint of heart, weren’t you?)

Signs and symptoms of internal parasites in dogs

While different parasites have different symptoms, there are some general signs of your poor dog having an internal parasite. Unlike external parasites, these hazardous organisms are very difficult to see and their eggs and spores can be impossible to detect with the naked eye. 

Some internal parasite infections are asymptomatic until it’s too late or the symptoms are very vague. If you see anything that just doesn’t look right with your dog, you want to get him or her to the vet as soon as possible. 

Signs to be on the lookout for include 

  • Vomiting
  • Weight loss or a lack of weight gain despite getting plenty of food
  • A distended abdomen
  • Diarrhea 
  • Poor coat appearance
  • Fatigue
  • Blood in stool

Your dog doesn’t need to have all of these symptoms to indicate it’s an internal parasite. If in doubt, get thee to a vet! Internal parasites are very dangerous to dogs and some can even be passed to humans. 

Diagnosis of internal parasites in dogs

If parasites are indeed suspected, your vet will take a fecal sample and test it. Your vet will also be able to tell you the severity and kind of infestation your dog has and how to best treat it. 

How a dog groomer can help identify internal parasites in your dog

Since your dog groomer gets up close and personal with your pup on a regular basis (and if that’s not the case, check out our blog on why it should be the case), your dog groomer will notice any unhealthy changes in your dog. 

Changes may look like a dull or thinning coat or weight loss. Your groomer will be able to see more subtle changes in your dog’s coat as well, such as it lacking shine. 

A less subtle, more obvious, and definitely more disturbing sign your dog groomer may notice are parts of a worm coming out of your dog’s anus. This is usually a tapeworm, more on that below. 

Types of internal parasites in dogs

There are a few common unwanted critters infecting your poor dog. The most common internal parasites in dogs are worms and single-celled organisms stealing your dog’s vitality. 

Image of a dog and cat looking at pictures of different internal parasites.
These are something worth sweating about! Find the original image here.


Roundworms are the most common worm infestation in dogs. These worms can live in the intestines of your dog, but also in other parts such as the lungs or other organs. They can become several inches long and steal your dog’s nutrients. 

Roundworms can be passed on to unborn puppies or through the milk if the mother was infected at any point in her life. Why? Because they can lie dormant for years! Roundworms can also live in soil for years making anything your dog eats off the ground a potential transmitter. 

This kind of worm can be transmitted to humans as well. Children who put dirty hands in their mouths are especially susceptible (make sure to thoroughly wash their hands with soap and water after being outside)! 

Roundworms look like white, firm, rounded strips that can be from one to three inches long. Sometimes, these are seen in the dog’s feces or vomit. 


Also common in dogs, hookworms can wreak havoc on your dog. Infection can occur from swallowing contaminated soil or fecal matter, just like with ringworms, but also from hookworms burrowing into your dog’s skin. Yikes! As with ringworms, it can also be passed from an infected mother’s milk to her pups. This kind of worm cannot be seen in the feces. 

This is a parasite that can also affect humans by penetrating the skin and causing a rash. 

Hookworms drink the blood of their unwilling host. They can cause weight loss, bloody diarrhea, weakness, and anemia. 


I know, I know. This just keeps getting better. You were warned.

Whipworms live in your dog’s intestine where the small and large intestines meet. While they can’t be seen in the dog’s feces, a sign is the stool covered in mucous. A severe infection may result in bloody diarrhea. 

This kind of worm, like the others, can be passed to your dog through the eggs living in the ground, where they can lie for several years. These worms are approximately one to three inches long and very thin. 

Humans cannot get whipworm (phew!). 


Tapeworms can grow up to a few feet in length in your dog’s intestines (I hope you’re sitting down for this). This infection can come from eating an infected flea or other small animal such as a rodent.

As mentioned above, these can be seen coming out of your dog’s anus (really, I keep warning you!). 

While gross and not pleasant, tapeworms are not fatal in dogs, though you still want to get rid of them. They can be passed to humans but the chances are low.


Heartworms play a very serious game and can be fatal. They can be spread through an infected mosquito and can result in severe problems such as organ damage and heart failure. They look like long strands of cooked spaghetti and live in your dog’s heart, lungs, and blood vessels. 

Image shows the heartworm life cycle in dogs from mosquito bite to full full fledged infection.
Heartworm life cycle, original image can be found here.

Coccidia, Giardia, and Spirochetes

These non-worm, single-celled organisms also fancy stealing your dog’s nutrients. Some dogs become immune to them while others will suffer greatly. 

  • Coccidia is more commonly found in puppies and can be passed on from an infected mother. Dogs may also pick this up from infected soil or feces. Diarrhea or weight loss, as with other parasites, may be a symptom. 
  • Giardia is found all over the US and can be passed to your dog from other animals as well as the typical culprits, infected soil, food, or feces. Giardia can cause diarrhea, stomach pain, and vomiting. However, sometimes an infected dog will have no symptoms.
  • Spirochetes are bacteria that live in the bloodstream and get their name from their spiral shape. This bacteria can be found in areas with wet, still water. It is especially dangerous for dogs with compromised immune systems. However, it can also be dangerous for healthy dogs. 

Treatment and prevention of internal parasites in dogs

After reading all of that, you didn’t think we would leave you with nothing to do, did you? Prevention is of course ideal, who wants to deal with all of this terror?

Luckily, there are plenty of preventative medications that your dog can take. Talk to your veterinarian to find out what’s necessary to take in your area, as some internal parasites are more prevalent in some areas than others.  

Keep your yard feces-free as this is a way that some parasites are spread. 

On that note, don’t let your dog eat anything touching feces or standing water, which is a breeding ground for Giardia. 

Take your dog to the veterinarian regularly, where the vet will test their feces to make sure there are no internal parasites already present. 


Treatment will of course depend on the type of internal parasite your dog has and the severity. Prescription medication, either taken orally or injected, will likely be necessary. Additionally, you will need to make sure anything that’s contaminated is cleaned. You’ll have to be especially careful when handling your dog’s feces. 


Internal parasites in dogs are a nasty business! Rather than having to deal with them, it’s best to prevent them (an ounce of prevention…right?). Your dog groomer can help alert you to potential signs of a problem, such as a dull coat, but be sure to take your dog to the vet regularly and get a fecal test.

If this article had you squirming, you’re not alone! Prevent this from happening to your dog! 

What did you think? Let us know in the comments below. Is this something you’ve ever experienced with your dog? Has your dog groomer ever helped you identify a problem in your dog? 

Leave a Comment

Your email address will not be published. Required fields are marked *