Signs of Worms in Dogs… And How To PREVENT Your Dog From Getting Worms In The First Place!

Signs of worms in dogs are not necessarily easy to see to the untrained eye.  As humans and living in most first world countries, we simply do not have to deal with most parasites and worms nor the treatment that goes with living with these types of worms and their symptoms.

But most people do not recognize the signs of worms in dogs; and did you know that if your dog has worms that this can actually lead to these parasites infecting you and your family? The truth is that children and geriatric people; those with weakened immune systems are at highest risk for infestation, infection and the symptoms of worms.

A large majority of puppies and kittens are born with worms.  This is why veterinarians treat these parasites before any symptoms of worms or infections are likely to be seen.  It is better preventative medicine to deworm puppies and keep adult dogs on a monthly dewormer, than to wait for symptoms of worms to present and cause infection and intestinal distress.

Signs of Worms

The signs of worms can be different depending on what type of worm the dog may have and the type of infection, intestinal distress and symptoms he is showing.  We will discuss these parasites at length further in the article.

However there are some general symptoms that automatically denote a sign of worms or intestinal parasites that often live in the intestinal tract and present in your dog’s feces.  These signs are as follows:

  • Bloated Belly (dogs might look overweight)
  • Loss of Apetite
  • Weigh Loss (your dog might suddenly lose weight and look skinny)
  • Lethargy
  • Dingy Fur
  • Vomiting
  • Diarrhea
  • Bloody or Mucus(y) Diarrhea
  • Failure to Thrive
  • Actually Seeing Worms on the Anus or in the Feces

Types of worms vary greatly from intestinal worms to heartworms and heartworm disease.

Most of these worms can be diagnosed and treated by your veterinarian.  Your veterinarian and his or her skilled staff or the laboratory that they use are all well skilled in identifying types of worms.

20 years ago, as a veterinary technician I used to look at a lot of fecal samples that were brought in by owners to try and diagnose types of worms or worm infestation.  In veterinary medicine today (at least at most of the practices that I have worked in, in the past 10 years), most veterinarians prefer to send fecal samples out to see if the dog has worms.  The laboratory employs employee’s whose only job is to look for larvae or the eggs that are seen in fecal samples.  Instead of entrusting a new veterinary technician to evaluate your dog’s fecal sample for worms or worm eggs, when veterinary technicians are also busy tending to surgery and animals, and vaccinations; it is more probable that the laboratory that your veterinarian uses (Antech or Idexx diagnostics) is more skilled to ascertain if your dog has worms.

Once the worm or worms, parasites or infection has been identified the appropriate treatment and drugs will be recommended by your veterinarian.   These treatments and or drugs should kill the worms, but regular prevention must be taken to prevent new worm infestations and symptoms of worms in your dogs and cats!

First Let Us Talk About Intestinal Worms

The most common type of worms in dogs is a variety of kinds and types of intestinal worms found in your dog’s feces.

Although some dogs will excrete a live worm, most worms (as mentioned above) are diagnosed by evaluating your dog’s feces and looking for worm eggs.  Eggs are seen and evaluated by your veterinarian or his lab using a high powered microscope and other tools.

And, remember!  Some of these worms can be transmitted to you and your children!  So it is crucial to have your dog’s feces evaluated and checked each year and to provide preventative medicine and medication to prevent transmission of worms and disease.

Type of worm is important, so let us start there!


Let us start with hookworms, because I think that hookworms can be the most terrifying of the types of intestinal worm infection that a dog can have because this one is very transmittable to humans.

Hookworms as the name implies hook into your dog’s intestinal tract and filters the blood out of your dog to survive.  They are even referred to as an extremely dangerous parasite.

If left untreated these worms can often kill puppies and kittens and dogs with weakened immune systems.

Symptoms of Hookworms

  • Blood in feces
  • Diarrhea
  • Anemia
  • Coughing (severe hookworm infestation means that the hookworm can make their way to the lungs)
  • Pale lips, nose and ears

Because these worms are leaching blood they can cause serious and dangerous infection.  These worms can also move through the body if left untreated and travel to the lungs.  Severe infections will cause anemia and paleness because the dog is losing blood faster than they can make more.

In humans, hookworm larvae or immature worms can be transmitted through contaminated soil or can even be transmitted if your dog licks his anus and then licks you or your child in the mouth.  It is this fact that keeps me from allowing dogs to lick me in the face and mouth and something that also makes this worm more dangerous for children (who are more likely to accept face and mouth kisses).

The hookworm larvae can also travel through damaged internal organs and even the eye, which can cause blindness and severe complications.

Prevention is the most important aspect of avoiding these worms for you and your dog!


Whipworms can also live in your dog’s intestinal tract and be more dangerous than some of the other intestinal worms because if treatment is not completed these worms can form an immunity or resilience to some of the drugs used to kill them.

Symptoms of whipworms:


Roundworms can also be found in your dog’s intestines and intestinal tract.

Roundworms come in two forms, one is more dangerous because it can be transmitted to you and your children.

The eggs of the roundworms which can be found in the soil or transmitted fecal to oral (just another reason not to let a dog or puppy lick you on the face or mouth).  I think people think that fecal to oral will never happen to them… however many, many people allow their dogs to lick them and of course dogs often lick their anus; hence fecal to oral dog transmittance to humans.

Symptoms of roundworms:

  • In humans severe vomiting and pain in the abdomen or intestines
  • In dogs
  • Distended or swelled belly (often seen in puppies and kittens)
  • Weight loss
  • Diarrhea
  • Lethargy
  • Coughing
  • In severe cases, the distended belly can rupture.

Sometimes these worms can even be identified in the stool of the dog.


Tapeworms can be tricky little devils!

Tapeworms can also be transmitted to humans and they are also one of the only types of worms that are difficult if not impossible to identify through fecal samples and evaluations. They’re common because tapeworms are usually transmitted when a dog digests a flea.  So dogs that have fleas, or dogs that kill wild animals like rabbits (etc) can be easily infected by tapeworms.

The tapeworm’s body is made up of tiny segments.  Each segment of these tapeworms has it’s own digestive and reproductive system.  These worms are typically identified as white pieces of worm in feces or what looks like rice around the anus of your dog, or even in severe cases what looks like rice where the dog sleeps.

Tapeworm infections can be fatal.

Symptoms of tapeworms:

  • Biting at anus
  • Scooting or dragging his rear end

Avoid tapeworm infections by keeping your dog on flea and tick medication year round.  Also spray your yard for fleas.  Make sure that fleas are not a part of your dog’s life!


Giardia  is actually not a worm, but a parasite and protozoan that can also give your dog projectile diarrhea and weight loss.

This protozoan is easily passed to humans as well as several other animals.

We used to see a lot of this kind of infection in Colorado when I worked there as a veterinary technician.  The parasite and protozoan giardia is often carried by birds.  We used to explain to our clients that this is why people don’t drink from streams and other standing water.  However, many of the dogs did, and most had ingested the protozoan even if it was not in the cyst shedding cycle.

When giardia (almost impossible to completely get rid of) infects the host and is it’s infectious stage cysts are shed.  When feces are evaluated by your veterinarian or the laboratory the evaluation is looking for these cysts.

I saw a lot of giardia in Colorado when I lived and worked there and evaluated feces samples.  Giardia, interestingly enough is a tear drop shaped protozoan that kind of appears to have a smiley face when evaluated under and with the help of a high powered microscope.  They are also kind of translucent. Typically ,these protozoans are much smaller than the eggs we see when we are looking for worms in dogs.

Treatment of the giardia cyst is usually very effective.  But killing the protozoan entirely is, again, nearly impossible.  So the protozoan usually lies dormant in the intestinal tract of all those that are effected and infected.


Another type of intestinal parasite is called coccidiosis, it causes watery and mucous based diarrhea in dogs and can cause damage to the intestinal tract if not treated.

Causes can be as simple as stress from boarding or moving or really anything that your dog finds stressful once the parasite is obtained.   The parasite is spread by the fecal matter of other infected animals and again is fecal to oral transmission.

Coccidiosis is most frequently found in puppies who have developed the infection by being exposed to the feces of infected adult dogs.  Remember puppies put their mouths on EVERYTHING.  Unfortunately, it is also particularly dangerous to puppies and dogs with weakened immune systems.

However, it is easily diagnosed through the examination of a fecal by either your veterinarian or the laboratory in which he uses.  And, thankfully it is easily treated once effectively diagnosed.

Again, as with giardia, eradication is nearly impossible with this parasite.  This is why stress later in life can cause a flare up.  But treatment of the symptoms can be very effective.  Once your veterinarian has diagnosed your dog or puppy with coccidia often seeking treatment will be easy.  Although just remember that there are so many reasons that your dog might have diarrhea, with the worms etcetera as mentioned above, that he might want to evaluate a sample again anyway.

Treatment of Worms and Parasites

The treatment of severe infections of each type of worm and several other types of parasites will be different depending on the worm or parasite.

Thankfully there are a number of prescription drugs available to your veterinarian that will treat them and some that will totally get rid of them.

It is a good idea to get a fecal sample any time that your dog has diarrhea or is having other aforementioned issues so that a test can be run.  The good news?  It only takes a 1 gram size of sample for your vet to run an effective test.  You don’t have to pick up the whole pile or even much of it to have a fecal sample run!  Your vet can even give you an easy to use tube to touch it hands free.

This pretty much concludes the most common intestinal worms and signs of worms in dogs.  Most of the most common heartworm monthly (or otherwise) medications also treat your dog monthly for worms.  Heartworm medications like Heartguard and other such types of heartworm medications also deworm your dog each month or treatment.   These medications kill all or most on the list except for tapeworms.  Tapeworms require a special type of medication that isn’t as readily available.  You can always look into alternative therapies but we don’t recommend it.

And, all of these reason and symptoms and dangers are why your veterinarian deworms puppies and kittens regularly!  Worms are dangerous and can be transmitted by the mother of the puppies and kittens.

I have saved one of THE MOST DANGEROUS worms for last.


Heartworms are dangerous and deadly!

Heartworms are also COMPLETELY PREVENTABLE!  Unlike being born with intestinal worms or getting them from mom’s milk; heartworms are not transmittable at birth or by the mother.

Heartworms are transmitted by mosquitos.

A mosquito bites a dog, fox, coyote, or wolf with heartworm disease and the baby heartworm called microfilaria are ingested by the mosquito.  These baby worms or larvae then develop inside the mosquito into the “infective stage” of the worm (a period of 10 to 14 days).  Then, when the mosquito bites a dog or another susceptible wild animal the infectious larvae are transmitted to the new host via blood and the bite.

Once inside the new host it takes about 6 months to develop and sexually mature (this is why we test dogs over 6 months and recommend prevention starting when dogs are puppies).  Once mature these worms can live in the animals heart 5 to 7 years and create great complications and death.  Each mosquito season can provide more opportunity for infection and damage to a pet that already has heartworm disease!

Symptoms of heartworm disease

Most symptoms are not shown until the disease has developed to a heavily infected state.

  • Persistent cough
  • Fatigue
  • Loss of appetite
  • Weight loss

It can also progress to heart failure, and a sudden death of the worms can cause blockage of the heart and cardiac collapse which typically results in death.

And, let’s face it mosquitoes are everywhere!!  I have heard clients say “my dog doesn’t need heartworm prevention because he never goes outside”  and our answer is that it is simply impossible to keep all mosquitos from entering your home.  Dogs in all states are at risk and some higher than others.

Heartworm disease is easily diagnosed through a blood test run by your veterinarian.  And prevention comes in many forms these days from monthly pills to products that last several months (but may be more dangerous).  And prevention is generally cheaper and safer than heartworms.

Treatment can cost upwards of $1000+ and it’s also dangerous because some of the worms must be killed but to kill them all will cause cardiac collapse and death.  So treatments must be spread out over a few weeks.

Treatments are also VERY PAINFUL for your dog.  The injection and injection sight become painful for the majority of dogs.

And, treatment requires complete crate rest while the treatments are ongoing (for several weeks) because exercise during treatment can cause more strain on the heart and cause death.

So if we have learned anything about signs of worms in dogs, symptoms, diagnosis, and treatments; I hope that we have learned that prevention is WAAAAAAAY better and cheaper than treatment.

Interestingly as I sit here and write this article we had a new case diagnosed just this week in our clinic!  He is probably one of a handful of dogs just our clinic has seen in MD.

Talk to your veterinarian about prevention today!

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