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Symptoms of Flea Collar Poisoning in Dogs (And Treatment)

Flea collars can cause problems for some dogs, even though they are considered safe. Dogs that are sensitive to the active ingredients in flea collars can develop local or general allergies. If the product or the residues left on their skin and fur are ingested, they can become intoxicated.

When you have a dog, external parasites are a constant problem. 

To prevent them, you have to apply antiparasitic substances every month or every few months, depending on the product.

Among the most popular antiparasitic products are flea collars. Although they are very effective against fleas and ticks, they can be dangerous for your dog.

In this article, you will learn if flea collars are toxic to dogs, the symptoms of flea collar poisoning in dogs, the causes of poisoning, and how to treat flea collar poisoning in dogs.

What Is a Flea Collar?

A flea collar is an effective antiparasitic product against fleas and ticks on dogs. It can last up to eight months, depending on the product. As with other antiparasitic products, flea collars have different concentrations depending on your dog’s weight.

Flea collars work by gradually releasing active ingredients, creating a reservoir. These ingredients spread throughout the dog’s body through the oils on the fur and skin.[1]

Flea collars are effective against several parasites, depending on the product and the active ingredients: [2]

  • Fleas
  • Ticks
  • Mites
  • Lice
  • Black flies
  • Gnats
  • Sandflies
  • Mosquitoes

Their effectiveness can last from four to eight months.

A flea collar is placed on the dog’s neck and tightened until it comes in contact with your pet’s skin. Leave enough space to insert two fingers under it.

What Is a Flea Collar
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Are Flea Collars Toxic to Dogs?

Flea collars are not toxic for dogs if you apply them properly. Poisoning can occur if your dog reaches the collar and licks or chews it. Dogs can be sensitive to the active ingredients and develop a local or generalized allergy.

While most flea collars are safe for dogs, some products can leave chemical residues on your dog’s fur and in the house for a few weeks.[3]

The active ingredients commonly used in flea collars are:[4]

  • Amitraz
  • Organophosphates (e.g. tetrachlorvinphos)
  • Carbamates (e.g. propoxur)
  • Pyrethrins/pyrethroids

Tetrachlorvinphos and propoxur are among the most dangerous pesticides. These pose a risk to pets, children, and adults.

Some flea collars can leave residue levels up to 1,000 times higher than those approved by the Environmental Protection Agency (EPA). These high levels can lead to cancer and damage the neurological system.

Are Flea Collars Toxic to Dogs

What Is Flea Collar Poisoning in Dogs?

When flea and tick collars are accidentally ingested or improperly applied to pets, they can cause severe symptoms that can endanger their life. While generally considered safe, these collars can cause harm.

A great number of substances can lead to poisoning in dogs, including pesticides in flea collars. 

These substances can be extremely powerful, with aggressive effects on a dog’s body. If your dog licks or swallows a piece of a flea collar, it can lead to severe poisoning.

The residues these products leave on your pet’s fur are also dangerous. They can persist for weeks and you and your family members can get sick if you accidentally ingest them.

Amitraz and propoxur are two substances that can be extremely toxic if ingested and can lead to severe poisoning.

Be aware of the toxic potential they have in dogs and humans, especially children if you decide to use these kinds of products.

Causes of Flea Collar Poisoning in Dogs

Flea collar poisoning in dogs can occur due to accidental ingestion of the product. Flea collars should not cause intoxication in dogs if used properly. If your dog shows signs of intoxication, contact your veterinarian immediately.

The residues these pesticides leave can remain in a dog’s fur for a few weeks. The risk of a dog becoming intoxicated increases when the flea collar is not applied properly as your dog may lick or chew it.

You and your family members can also get sick. 

If you touch the area where the collar is placed, and then put your hands in your mouth or on your food, you may be ingesting harmful chemicals.

Causes of Flea Collar Poisoning in Dogs

Do the following to minimize the potential toxicity of these products:

  1. Make sure you apply the collar properly. The product should be in close contact with your dog’s skin and you should be able to insert two fingers under it.
  2. Try as much as possible not to touch the collar.
  3. You should wash your hands after applying the flea collar or petting your dog in that area.

Chihuahuas and Pomeranians are more sensitive to flea products containing amitraz. Keep this in mind if you own one of these breeds.

Symptoms of Flea Collar Poisoning in Dogs

The symptoms that occur in flea collar poisoning are neurological and digestive. Some dogs may also develop local or generalized allergies. If your dog starts behaving strangely after applying the flea collar, contact your veterinarian.

Some pesticides in flea collars can lead to severe cases of intoxication if ingested. The most common ones are amitraz and propoxur.

Loss of bodily movement controlLoss of bodily movement control
Abnormal heart rhythm and rapid heart rateAbnormal heart rhythm
Excess salivationSalivation
High or low body temperatureNausea
DepressionMuscle twitching
DiarrheaAbdominal cramps
Urinary incontinence 
Low blood pressure 
Gastric dilatation 
Difficulty breathing 
Dilation of pupils 
Obstruction of the intestines due to paralysis of intestines 
Loss of appetite 

Propoxur may also cause a local skin reaction which is manifested through

  • Redness
  • Itching
  • Hair loss
  • Pupillary constriction

Regarding generalized allergies, some dogs may be sensitive to one of the active substances, and their body can react to them through:

  • Itching
  • Scratch
  • Irritation
  • Vomiting
  • Diarrhea
  • Tremor
  • Depression
  • Depression
  • Respiratory distress
  • Death (in very rare cases)

In mild allergies, your dog may present:

  • Hypersalivation
  • Vomiting
  • Diarrhea
  • Mild depression
  • Paw flicking
  • Ear twitching

If your dog shows any of the symptoms mentioned above after applying the flea collar, contact your veterinarian as soon as possible.

Symptoms of Flea Collar Poisoning in Dogs
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Diagnosis and Treatment of Flea Collar Poisoning in Dogs

A diagnosis of flea collar poisoning is based on symptoms and complementary tests. The sooner you get the dog to the vet, the faster they can initiate treatment. Severe cases of intoxication or allergy can lead to your pet’s death.

If your dog shows signs of intoxication or allergy, remove the flea collar from its neck immediately. If it has swallowed a piece of collar, go to the vet immediately. Do not induce vomiting on your own unless instructed by your veterinarian.

You need to provide as much information as possible for a proper diagnosis. These are things such as recent illnesses or how long your dog has been showing symptoms.

Your veterinarian may also perform complementary tests, such as blood tests, x-rays, or ultrasounds, but it depends on your dog’s health.

Blood tests show how damaged the internal organs are, while x-rays may show the location of the piece of collar your dog ate.

The treatment of flea collar poisoning is based on the severity of the intoxication. In severe cases, your dog’s blood pressure, heart rate, urine output, and blood markers can be monitored at regular intervals.

If your dog has swallowed a piece of collar, an endoscopic procedure may also be performed to remove it.


Flea collar poisoning happens when a dog ingests chemicals from a flea collar, a piece of the flea collar itself, or if the collar is applied improperly. 

If you notice nervous or digestive symptoms, redness, itching, or excessive salivation, do not hesitate to contact your veterinarian. The sooner you get to the vet, the better your chances of saving your dog’s life.


Can a Flea Collar Make My Dog Sick?

Yes, a flea collar can make a dog sick if it licks or chews the product. Usually, flea collars are considered safe, but for this, you have to apply them properly to your dog’s neck. Tighten the collar until you can insert two fingers under it.

Do Flea Collars Have Side Effects?

Flea collars do not usually have side effects unless your dog is allergic to the active ingredients or chews the product. If you see redness or itchiness at the application site, excess salivation, or neurological or digestive symptoms, contact your veterinarian as soon as possible.

About Iulia Mihai (DVM)

Dr. Iulia is a certified veterinarian with more than 10 years of experience in the field. With extensive knowledge of diet, care, and medication, she helps Misfit Animals provide readers with accurate knowledge on technical topics.

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