Can Worms Cause Hair Loss In Dogs

Can Worms Cause Hair Loss In Dogs?

Last Updated: August 18, 2023
correct answerThe Short Answer is:

Having worms in your dog should not cause hair loss by itself. Worms can cause considerable distress to a dog and its owner, but they do not cause hair loss.

In this article you will know the answer to the query “Can Worms Cause Hair Loss In Dogs?“.

Have you recently noticed that your dog is losing hair after having been treated for an infestation of worms?

Can Worms Cause Hair Loss In Dogs

Despite the fact that it is not impossible it is highly unlikely that this hair loss is caused by worms. 

Let me explain why.

Top Treatments Worms

Having worms in your dog should not cause hair loss by itself.

Worms can cause considerable distress to a dog and its owner but they do not cause hair loss.

In any event worms are commonly treated with a variety of medications so I wondered whether any of them might have any known side effects such as hair loss. 

I just browsed a list of the most popular medications used to treat dogs for worms. 

Here are their names:






In veterinary practice all of these medications have been used successfully for years and they are all considered to be safe.

However all medications have the potential for side effects so I dug deeper to learn about the side effects of each of these drugs. 

The only medication known to cause hair loss in dogs out of all of them is fenbendazole.

Itchy skin and hives are described as side effects of this medication which could lead to hair loss in dogs. However it is very rare for this medication to cause any side effects.

Any of the other listed drugs have no known side effects that could lead to hair loss in dogs. Aside from seizures muscle spasms and excessive drooling the side effects did not directly lead to hair loss. 

The case of moxidectin is interesting. The known side effects of this medicine are panting and muscle tremors in dogs but excessive grooming and scratching in cats. 

What do we mean by worms?

Did you know that dogs are commonly infected with 6 different types of worms? I was unaware of such a wide variety of types myself…

Just thinking about these things makes me disgusted

The roundworm

The tapeworm

The hookworm

The Whipworm 

A heartworm

The lungworm

Lets go over some of the main points about these worms.

These worms can be passed from dogs to humans so prevention is extremely important. 

The dogs intestine is home to all but two of these worms. Dogs can get heartworms which live in their hearts as well as lungworms which breed in their lungs. 

Among the most common worms are roundworms which puppies inherit from their mother when they are born. 

It is possible for dogs to become infested with many of these worms if they consume wild animals such as rabbits or birds dead or alive that become infested with them.

Due to the amount of blood they consume hookworms can be fatal to puppies. 

When they live in a dogs heart heartworms are by far the most dangerous type of worm.

Mosquitoes transmit these worms and they are more prevalent along the Atlantic and Gulf coasts of the United States. 

Six common symptoms of worms in dogs?

When examining worms in dogs there are two difficulties.

The symptoms are not limited to worm infestations. They include weight loss for instance. Your dog could be suffering from any number of diseases not just worms if its losing weight.

Additionally the best way to tell if your dog has worms is to see them in their feces vomit or on their bottom.

However you would not necessarily see worms on your dog if it has them. 

It is unlikely you will be able to see any other type of worm in your dogs stool since it can only be identified by examining a stool sample under a microscope.

Having said all that here are the six most important signs that your dog has worms.

  1. Worms in dog’s feces or on dog’s bottom
  2. Diarrhea and vomiting
  3. Weight loss
  4. Swollen stomach
  5. Lethargy
  6. Abdominal pain

[1] According to what we have already said this is your best symptom because a dog with worms will definitely have them.

The symptoms [2 3] [4] and [5] are all physically obvious – you can tell when they are happening just by looking at them. The only thing you do not know is whether they indicate worms collectively or individually.

[6] is a more difficult one to spot. It may be easy to recognize that your dog is in pain but it is more difficult to confirm that the pain is coming from the abdomen. 

How do dogs get worms?

Dogs can get worms in five different ways.

*Eating contaminated food

Its time to get gross again. 

In 2012 a study showed that 16% of dogs or one out of six of them ate stool regularly and 25% or one out of four ate stool at least once. 

A similar study found that female dogs are more likely to eat fresh stool than male dogs and on nine out of ten occasions dogs prefer to eat fresh stool over “older” stool.  

*Eating touching or ingesting soil contaminated with bacteria

As you can see it has to do with the fact that a patch of ground that has been infected by worms or fleas (via stool for example) can stay infected for months. Regardless of whether the dog walks on the soil and then ingests tiny particles as they clean themselves they are at risk. 

* Consuming infected grass

The grass is eaten by dogs. They might eat it if it has water on it and they are looking for a drink or even if they are trying to make themselves vomit or balance their diet by consuming plants.

*Lmbibing fleas while grooming

My first impression of this was somewhat frightening and I only realized it after doing some research.

Whenever a dog grooms itself it might accidentally swallow a flea if they have fleas. 

It almost seems like dogs chew their skin with their front teeth when they groom themselves does not it? 

Suddenly you realize yeah thats not so crazy after all. 

As a result the dog is at risk of contracting worms if those fleas are infected with worms.

Therefore flea treatment should be done on a regular basis

A type of worm that has been infected with wild animals (dead or alive). Rats rabbits and birds have been known to carry this worm.  

Unsavory option number two!

What percentage of dogs are guilty of this?

Right now my sister-in-law is struggling with something very similar. 

The dogs favorite pastime is to disappear into the hedgerows and come home with a dead rat or pheasant in its mouth. Yum!

The biggest risk of this would have been an upset stomach but now it seems that worms may be the biggest risk.

Do you ever want to let your dog out again after reading that list? 

It is all-encompassing and a little frightening. 

8 common causes of hair loss in dogs

Currently it is unlikely that an infestation of worms is the cause of your dogs hair loss.

What do you think it is?

These are the eight most common causes of dog hair loss

An infestation of parasites such as mites fleas or lice

Anxiety or parasites due to overgrooming

There are three types of skin conditions: eczema dandruff and hot spots

Nutritional deficiencies are also a concern

Food allergies are among the top five

Cushings disease and cancer tumors are complex conditions

There are seven types of scars or wounds

The eighth condition is inherited

Top treatments for hair loss

Due to the wide range of causes of hair loss in dogs there is also a wide range of treatments.

Here are some of the best and most common treatments

Infections and inflammations are treated with antibiotics antifungals and steroids

Allergic reactions can be treated with antihistamines

(with hydrocortisone) Medicated shampoos 

Medication for ticks and fleas

Overgrooming collar – Elizabethan

Natural/ holistic treatments

There are a few holistic solutions I can recommend for you to try if you want to go that route. You can use a humidifier apple cider vinegar or lemon juice. 


Therefore it appears that worms are unlikely to be the cause of your dogs hair loss. 

It is very unlikely that a medication used to treat your dogs for worms will cause hair loss but it is possible. 

I have discussed several of these factors in this article but the most likely cause of your dogs hair loss is not worms. 

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Amanda Dogs Trainer

Amanda (Author)

With over a decade of experience, Amanda is a distinguished dog trainer. Her expertise in canine behavior has transformed countless lives, fostering harmonious human-canine connections. Through compassionate and personalized approaches, she empowers owners to understand and connect with their furry companions, creating a legacy of joyful tails and transformed lives.

Osvaldo Maciel Dogs Trainer

Osvaldo Maciel (Content Reviewer)

Osvaldo Maciel, a stalwart in the field with 14 years of experience, is a revered dog trainer. His journey is defined by a profound understanding of canine behavior, shaping unbreakable human-canine bonds. Osvaldo guides owners to connect with their beloved pets, leaving an indelible mark of happiness and transformation. His legacy shines through the countless lives he has touched.

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