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Dogs Acting Weird After Applying Frontline

Frontline in Dogs

Having dogs acting weird after applying Frontline may feel quite disheartening to dog owners. When dog owners apply a product to combat fleas on their dogs, they feel good about it as they're protecting their dogs from pesky parasites and certainly don't expect to see dogs acting weird after applying Frontline or any other products against parasites. Yet, a number of dog owners report that their dogs acting weird after applying Frontline, why is that? Unusual behaviors include restlessness, disorientation, itching and scratching, whining, chewing body parts or just acting weird or lethargic. It's important to always keep a watchful eye on dogs after applying products such as Frontline because some dogs may have adverse reactions.

frontline-side-effects, Dogs Acting Weird After Applying Frontline

Dog scratching after applying Frontline

Dogs Acting Weird After Applying Frontline

Frontline and other topical flea products using the same mode of action tend to get stored in the oil glands of the skin and remain there for up to a month, so if a problem is recognized, it's important to remove traces of this product as soon as possible.

It's important to recognize though that, shortly after applying Frontline, some dogs may scratch more as the fleas tend to become hyperactive before dying which can end up irritating the dog, according to Frontline's FAQ.

So dog owners should determine whether their dogs are dealing with a normal reaction due to the dying fleas scurrying around the dog's coat or some type of allergic reaction.

"The active ingredient in FRONTLINE (fipronil) kills fleas by affecting their nervous system, making them hyperactive before dying. These dying fleas often rise to the top of your pet's haircoat, so the presence of visible fleas after treating your pet is a sign that the product is working."~Frontline UK.

Dawn for Dogs

dog dawn detergent

For dogs acting weird after applying Frontline or having a reaction to Frontline, it's very important to take action quickly. One thing you can do is try bathing your dog in a dish soap, such as Dawn, a few times so to remove traces of Frontline and see if that gives the dog relief, suggests veterinarian Dr. John. 

Dawn in this case works particularly well because Frontline concentrates into the dog's sebaceous glands of the skin and stays put for a month, even if the dog is bathed or groomed. It is important therefore to bathe the dog within 48 hours of applying the product. After 48 hours, bathing is probably minimally effective as, by then, a great part has been already absorbed.

An effective product that cuts through grease is needed and Dawn is one of the preferred products used to remove oil spill residues from birds. More than one bath with Dawn may be needed to remove all residue.

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"The active ingredients of Frontline usually takes about 24 hours to be completely absorbed by the top layer of skin. I would recommend washing with the likes of Dawn dish soap, do this twice and rinse the area well each time."~Dr. Scott Nimmo, veterinarian

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Benadryl for Buddy

Dogs acting weird after applying Frontline such as appearing itchy may also benefit from an antihistamine. Plain Benadryl containing only the ingredient diphenhydramine is an over-the-counter medication often given to dogs who are having allergic reactions.

According to veterinarain Dr. Christian the Benadryl would give relief and make the dog a bit sleepy, however, if there is no improvement after an hour or two, affected dogs may need a steroid shot to stop the reaction to the Frontline. Consult with your vet before giving any over the counter products to your dog.

Benadryl can be given at a dose of 1 mg for 1 pound of body weight. Now, Benadryl comes in different forms and sizes. It is best to avoid the liquid form as in large dogs you would need to give too much of it. Tablets are far better. A 25 pound dog will therefore get a 25 mg tablet or half of a 50 mg tablet, explains veterinarian Dr. Andy

A Word About Toxicity 

Mucus in dog's stool

Owners of dogs acting weird after applying Frontline may be wondering about the safety of this drug. Fipronil is the active ingredient of Frontline and research has shown that fipronil has a wide margin of safety.

When applied to the skin, fipronil is not found to be significantly absorbed by the dermis; rather, it remains confined on the hair and superficial skin layers. More specifically, fipronil accumulates in the dog's sebaceous glands and follicular ducts, from which it is gradually released over the course of several weeks.

Adverse side effects to the skin have been occasionally seen in sensitive dogs, with skin irritation and hair loss affecting the site of application. Most of the time, cases of fipronil poisoning occur in dogs from accidental ingestion.

Ingestion of fipronil may result in neurotoxic symptoms such as tremors, convulsions, seizures, and death. It would take though quite a significant dose to cause such problems. If you suspect your dog ingested a significant amount, consult with your vet immediately or contact the Pet Poison Helpline at 855-764-7661. Have your credit card ready as a $59 per incident fee applies.

"Frontline is pretty harmless when ingested. The stomach acid breaks down the product and leaves it ineffective. It would take a whole boatload to cause any toxic side effects- those effects would be muscle tremors, hyper sensitivity and seizures."~Dr. Gary

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  • Chemical Watch Fact Sheet: Fipronil
  • Science Direct: Fipronil

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