Seresto Killed My Dog

To prevent pests from infesting your furry friend, you chose to invest in a Seresto flea collar. However, while it was advertised to be effective in protecting your dog from fleas, your dog ended up passing away. It must be a devastating moment and you surely can’t have peace of mind until you understand how and why it happened. In this article, I will help you understand everything about the Seresto flea dog collar, how it might have contributed to the death of your dog, and much more.

What Is Seresto?

Seresto pet collars keep fleas and ticks away from your dog or cat. Over eight months, the collars gently and constantly release two active components (flumethrin and imidacloprid).

In dogs and cats, these active substances deter and eliminate ticks and fleas. Seresto repels and kills fleas, ticks, and chewing lice in puppies and dogs 7 weeks and older. Seresto can also be administered as part of a sarcoptic mange treatment regimen for dogs.

How Seresto Works

Seresto collars are formulated with 4.5% flumethrin and 10% imidacloprid. Over the course of 8 months, the collar gradually and continually delivers these ingredients onto your pet’s skin. The active components spread throughout the pet’s skin and haircoat, helping to defend against external parasites.

Seresto kills fleas on your pet’s body within 24 hours of applying the collar. If your pet wears the Seresto collar consistently for the following 8 months, any new fleas that land on him will be eliminated within 2 hours.

Since Seresto eliminates fleas before they may lay eggs, fewer flea larvae are present in the environment around the pet. Fleas can survive in the environment for up to six weeks as immature fleas or flea pupae because they are not affected

The Seresto label lists deer ticks, American dog ticks, brown dog ticks, and Lone Star ticks as susceptible ticks. Tick prevention begins within 48 hours of applying the collar. Following that, new ticks are repelled or killed within 6 hours.

Seresto Killed My Dog

Some of the predisposing factors that can lead to the death of a dog after using a Seresto collar include;

Underlying Health Condition

The pest-preventing substance in the Seresto collar is made to remain in your pet’s skin’s oils and oil glands, with no to very little absorption into your pet’s body. As a result, they are typically quite safe with rare systemic reactions. A systemic reaction could occur in a pet if there is an underlying illness or abnormality that allows for increased chemical absorption through the skin barrier. If not handled immediately, this could result in death.


Although the amount of active ingredients in the Seresto collar (imidacloprid and flumethrin) is low enough to be safe for your dog, the collar still poses a risk if it is placed improperly or if your dog ingests it.

Chewing on the flea collar can cause the chemicals to be discharged into your dog’s mouth and digestive tract. This may result in nausea, diarrhea, and other gastrointestinal problems. A significant amount of the chemicals in your dog’s system might cause more severe symptoms like seizures, tremors, and even death.

Fake collars

Fake collars, which are designed to look like the real thing and are typically priced lower than the actual product, may not only fail to protect pets from fleas and ticks but may also include substances that are harmful to pets.


The symptoms of an allergic reaction to a flea collar can vary, but often you’ll experience some redness, swelling, or itching where the collar is positioned. Additionally, your pet can scratch excessively or act uneasy.

More serious reactions, such as hives or respiratory problems, can occasionally happen and call for quick veterinarian care. If a dog has an allergic reaction to a dog collar and fails to receive immediate health attention, death can occur.

If you think your pet may be experiencing an allergic response to their flea collar, it is advisable to take the collar off and provide them with some comfort. You can also speak with your veterinarian for more advice. To help manage your pet’s symptoms, they might advise a different flea preventative or other treatment alternatives.

Seresto Safety

According to Elanco, more than 25 million collars have been distributed since 2012, and “as a globally marketed product, more than 80 regulatory authorities around the world, including the US EPA, rigorously reviewed the safety data collected over the course of Seresto’s development prior to registration and/or approval, as appropriate.”

Only 0.3% of the collars distributed cause adverse reactions. These concerns are frequently noticed in pets who are already known to be sensitive, and they resolve once the collar is removed. Seresto collars have never been proven to cause significant disease or death.

In 2021, the overall incident reporting rate was 17.26 reports for every 10,000 collars sold. That is less than a fifth of one percent. The great majority of these reports concern minor side effects such as temporary hair loss and mild skin discomfort near the treatment site.

Correlation vs. Causation

Pet owners need to distinguish between correlation and causation. Correlation occurs when two events occur at the same time. Causation is the process through which the first thing causes the second. When a pet dies, it’s usually terrible and painfully sad, and owners frequently opt not to perform a necropsy. A necropsy can help to confirm the cause of death, and many pet owners believe that a certain product killed their beloved pet without it, which is not always true. It is impossible to ascertain the true underlying cause of death without a necropsy and toxicology report.

So, while the Seresto collar may have been worn at the time the pet died, there’s no way of knowing if it was a factor in the pet’s death, it will still be listed as an “adverse event” by the reporting agency. This can lead to a pet owner blaming the Seresto collar when the dog may have been suffering from an unrelated health issue or had access to other toxins. There was no toxicology or necropsy performed on the pet in the majority of the reports of adverse effects, making it hard to tell if there was causation that the collar contributed to the pet’s death.

Seresto Collar Allergy Symptoms in Dogs

Below are signs to look out for after using Seresto collar on your do;

  • Runny nose
  • Watery eyes
  • Sneezing
  • Coughing
  • Wheezing
  • Respiratory distress
  • Skin inflammation
  • Loss of hair

These side effects are usually observed between a few hours to a few days after wearing the collar. Call your veterinarian if you experience any of these signs; you will likely be advised to take the collar off and give your pet a bath. It is unlikely that the medication from the collar will be absorbed into circulation because it is kept in the oil glands. A different class of preventatives may need to be taken into account if any of these reactions occur.

Can Seresto be used with Frontline?

Both Seresto collars and Frontline Plus treat fleas, ticks, and chewing lice. Seresto is also used to treat and control sarcoptic mange. Because both medications treat the same parasites, treatment with both products may not be necessary. Consult your veterinarian to determine which product(s) are best for your pet. When one flea and tick medication is ineffective, vets may give more than one.

 Are Seresto collars safe for dogs?

Consult your veterinarian before using this product in sick, debilitated, geriatric, pregnant, breeding, or nursing pets. Counterfeit Seresto collars have been discovered on the market; these goods are unsafe; thus, please check that you are purchasing your Seresto collar from a certified distributor.

Can Dogs Still Get Fleas With Seresto?

Yes, the answer is “Yes.” The Seresto Dog Flea and Tick Collar are quite effective. It is, however, not the ideal solution. The whole procedure is dependent on fleas biting into your pet’s skin. They will not consume the insecticide if they do not.

As a result, even if your pet is wearing Seresto, it may still have fleas and ticks on its fur. But that would continue for no more than a few hours. The fleas will eventually get them to bite, and when they do, they’ll be dead for sure.

Is Seresto dog collar water-resistant?

When a dog bathes or gets wet, Seresto doesn’t have to be taken off. The matrix of the collar contains active substances, which won’t leak into the water. Even if this lipid layer is partially wiped off by bathing the dog, the active components in Seresto will swiftly replenish, providing the dog with protection once more. They spread via the lipid layer of the dog’s skin and hair

The length of the activity may be shortened, thus prolonged, severe exposure to water or intensive shampooing should be avoided. Dogs should not be bathed more than once every month to maintain an eight-month duration.

For dogs who swim once a month or more, the control duration is shortened to five months for flea control and seven months for tick control.

Alternatives to Seresto

There are a variety of products available for protecting dogs from pests. Among these are dog flea and tick collars, topical flea and tick treatments, and oral flea and tick medications. You can talk to your veterinarian about the following choices if your dog is not responding well to the Seresto dog collar:

Oral Flea and Tick medications for Dogs

Spinosad (insecticide): Trifexis and Comfortis

Trifexis and Comfortis are flea medications for dogs that use the active ingredient spinosad to fight fleas. Spinosad is an insecticide based on chemical components present in certain bacteria.

It is crucial to remember that these items are only available as dog flea medications and are ineffective against ticks.


Bravecto offers tick and flea protection. This medication’s active ingredient and component, fluralaner, kills adult fleas and ticks. This medicine should only be administered to pets with a prescription from your veterinarian.


The active ingredient of Nexgard is afoxolaner. The oral medication begins killing fleas in 30 minutes and ticks in 24 hours after application. Additionally, it shields dogs from tick-borne illnesses including sarcoptic mange.  

Sentinel (lufenuron)

Sentinel is an insect growth regulator, which means that it stops flea eggs from hatching. Ticks are not effectively controlled by Sentinel.

Sentinel does not kill adult fleas; instead, it stops any eggs from hatching, which eliminates the flea population.

Topical Flea & Tick Treatment for dogs


Advantix is a monthly topical treatment for dog flea and tick infestations. It also functions as a repellent for 30 days in addition to destroying fleas and ticks. Advantix effectively breaks the flea life cycle by eradicating all flea life stages, including eggs, pupae, larvae, and adults. This prevents any other infestations from happening. Advantix delivers mosquito-borne heartworm disease defense in addition to all of the above.

Frontline Plus

Frontline Plus contains the active chemicals fipronil and (S)-methoprene, which are used for fighting fleas and ticks at all phases of development. It also eliminates ticks and aids in controlling flea outbreaks. 

Tick and Flea Collar for Dogs

Zodiac Flea and Tick Collar

The active ingredient in this collar is tetrachlorvinphos, which kills and repels adult fleas and ticks and begins functioning on contact, giving full-body protection to your dog.

Puppies as young as 12 weeks old are suitable candidates for the Zodiac Collar. Each collar has a seven-month effectiveness and cannot get wet thanks to its water-resistant design.

Hartz UltraGuard Pro Flea & Tick Collar  

The Hartz UltraGuard Pro offers complete body defense against ticks and fleas. Tetrachlorvinphos and methoprene are combined to kill and repel fleas in all phases of development, including adults, larvae, and eggs, and to stop flea eggs from hatching. It also protects against ticks, making it an excellent summertime defense against Lyme disease.


Unfortunately, the likelihood that a pet would become seriously ill from tick disease and suffer needlessly from flea allergy outweighs the likelihood that they will react negatively to flea and tick preventatives.

Although they are uncommon, allergic reactions to the Seresto collar are a possibility. If you see any itching, scratching, or redness where the collar has been placed, keep an eye out for indications of an allergic response. Also, remember to buy your flea and tick preventives from a recognized seller to avoid buying counterfeits which can do your pet more harm than good.

Before using any flea and tick remedies, do your homework so you can make an educated choice for your pet’s safety and well-being.

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