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What Happens If You Give A Dog Too Much Wormer?

If your dog is exhibiting signs of worms, we are guessing that you, like any good pet owner, would no doubt do all you can to ease your dog’s suffering and remedy the condition.

And if you take your dog to the veterinarian for a checkup—and that checkup reveals the presence of intestinal worms—your vet will probably prescribe some type of wormer to clear up the problem.

These wormers, which are also referred to as de-wormers, consist of very powerful medicine designed to kill the crawly little creatures in your dog’s digestive tract.

This process can take a number of days or even weeks, so it is crucial that you use the medication only as prescribed and directed, as too little might be ineffective in addressing the problem, and too much wormer could potentially cause harm to your dog.

To elaborate on this subject, below we will briefly describe the various types of worms that can plague your dog, and explain how wormer medication works, how it is used, and why too much de-wormer can bring unnecessary harm to your furry little friend.

As a bonus, we will also outline some do-it-yourself home remedies for tackling and preventing worms from infiltrating your dog’s digestive system.

Types of Worms a Dog Can Get

Dogs can present with a number of different types of worms, each as disgusting as the next.

Most of these worms live in your dog’s digestive system and can enter through a number of different means.

Here is a closer look at the types of worms commonly found in dogs:


The hookworm, whose scientific name is Ancylostoma Caninum, is a parasite that is almost always found in the small intestines of dogs.

As its name suggests, the hookworm is shaped like a hook.

The top, rounded or “C” section of the hookworm has a diameter similar to that of a dime.

In comparison to other worm types, hookworms have very large buccal (mouth) cavities, within lies three sets of teeth.

This feature of the hookworm allows it to easily attach to the walls of the small intestine.

Hookworms then feed on the blood of the affected dog.

When they are present in large numbers, hookworms can cause dogs to suffer from anemia due to blood loss, a condition which results in fatigue and a myriad of other symptoms.


Oddly, roundworms are usually not round at all, but rather long and thin, somewhat resembling cooked angel hair pasta.

Roundworms are very common in dogs, especially in puppies whose immune systems are yet too weak to fight off the parasites once they reach the adult stage.

According to experts, “almost all dogs will deal with roundworms at some point in their lives, particularly in the early stages.”

The most common type of roundworm in dogs is known scientifically as the Toxocara canis.

This type of parasite can grow to be several inches in length once it reaches adulthood.

Like hookworms, roundworms also live in the small intestine of the dog.

There, instead of feeding on blood as the hookworm does, they munch on partially digested food as it makes its way out of the stomach and into the intestines.

This can be problematic, especially for young growing pups, as the parasite robs the canine of nutrition—the vitamins and minerals it needs to flourish.

While hookworms are typically picked up by contaminated soil and other causes, most roundworms come into dogs via their mothers, with the larvae being transferred either prior to birth or when the puppy is first nursing.


A tapeworm is a long, flat segmented type of worm that is parasitic to say the least.

These worms can live in almost any part of the digestive tract, from the stomach to the small intestine to the large intestine.

Tapeworms can be found in many different animals, ranging from dogs and cats to livestock to humans.

The doggie version of tapeworm is scientifically known as Dipylidium Caninum.

These parasites can range in size from almost microscopic to several inches long.

In fact, their growth is only aided by the amount of partially digested food they consume while lurking in your dog’s gut.

So how do dogs get tapeworms?  Actually, the process is quite simple.

Unfortunately, it is also rather cyclical, meaning the process can continue playing out over and over again.

When dogs ingest a host containing tapeworm larvae, usually a flea, that larvae then hatches in a dog’s intestine, where the tapeworm can continue to feed and grow.

The segments of the parasite will often breakaway and exit the dog through his stool.

But sadly, those segments can contain tapeworm eggs, which are then consumed by fleas and other creatures, restarting the cycle.


Known scientifically as Trichuris vulpis, whipworms join the previously three types of worms as being the most common parasites to infect the intestinal system of dogs.

Whipworms, which are small in comparison to the other three types we have discussed, typically measure less than a 1/4 -inch in length.

They tend to inhabit the large intestines of dogs, specifically the cecum and colon areas.

Whipworms attach to the mucosal lining of these areas and feed off blood.

When their numbers are large, they can cause a number of unpleasant symptoms in dogs.

Other types of worms that can be found in dogs include heartworms, ringworms, pinworms and threadworms.

Wormer:  What Is It and How It Is Used

When you hear the term “wormer” or “de-wormer,” what is really being described is an anthelmintic or vermifugal drug or agent.

These drugs have been used for decades to rid dogs of different types of worms, drugs that include:

  • Piperazine.  This agent is used primarily to treat roundworm in dogs.
  • Hexylresorcinol. Another drug used to combat roundworm is known as Hexylresorcinol.
  • Pyrantel Pamoate.  This particular drug is effective against many different types of worms in dogs.  These include hookworms, pinworms and roundworms.  It works by essentially paralyzing the worms, causing them to lose their grip on the intestinal walls and thus be eliminated through the waste process.
  • Ivermectin.  Ivermectin is used almost exclusively for the prevention of heartworm in dogs.  It can also be effective in the treatment of dog lice and ear mites.
  • Fenbendazole.  Fenbendazole is another multi-worm treatment option, effective against parasites like hookworms, roundworms and whipworms.  It is also be used by vets in the treatment of giardia.

Important to note is that anthelmintic and vermifugal drugs can be very toxic to your dog if used incorrectly.

For this reason, it is vital that you use them only by prescription and only as directed by your veterinarian.

Can You Give A Dog Too Much Wormer?

So, if a little wormer works good for treating worms in dogs, more should be better, right?

Absolutely not.  Only a qualified veterinarian should prescribe these de-worming drugs.

Moreover, de-worming products that are available over-the-counter must be used EXACTLY as directed.

Failure to do so can have negative consequences that range from bad to catastrophic.

Anti-worming agents contain very strong and extremely toxic substances aimed at ridding your dog of problem parasites.

Because they are so robust and potentially toxic, these drugs—in larger quantities than is recommended—can lead to a number of troubling symptoms in your dog, including vomiting and diarrhea, both of which can lead to dehydration and all the problems that come with that condition.

Too much of certain types of wormers can also bring about organ problems—even organ failure—and potentially even death.

Bottom line:  If you love your dog, always use deworming products exactly as directed, and NEVER provide more than is recommended for the treatment of these parasites.

Failure to heed this simple warning can have disastrous consequences.

A Few Home Solutions for the Treatment of Worms in Dogs

If worms have become a problem with your pet, there are some things you can do that might make your dog feel a little more comfortable and help him fight off the parasitic infection.

Giving your dog coconut, for example, is a good start.

Whether you use dried coconut or coconut oil, just a little bit of this wonder food can help soothe your dog’s digestive woes.

Coconut has antifungal properties, which collectively can help boost your dog’s metabolism.

This metabolic boost can strengthen his immune system, leaving him better prepared to fight off the parasites that plague him.

Grapefruit seed extract can also be helpful.

The acidic nature of this substance helps to reduce the amount of mucus in the digestive tract—the very mucus onto which worm larvae tends to cling.

This allows that larvae to be expelled more rapidly as waste, while improving the overall efficiency of the digestive process.

Like grapefruit seed extract, the hulls of black walnuts are also very acidic.

By the same process, a little bit of this substance in your dog’s food can help sweep away the larvae of hookworms, tapeworms, roundworms and whipworms.

These are just a few of the many home remedies you can try while waiting for your vet-ordered deworming product to do its thing.

These home remedies are safe and vet-recommended, and they will never harm your dog in the way an excessive amount of wormer almost certainly would.

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National Canine Research Association of America