The chemicals that are put into the flea and tick collars that many dog owners use to eliminate fleas from their pets can be harmful if eaten. Serious effects on the central nervous system resulting in neurological deficits are possible.  In addition, the ingredients in the flea collars can leave a residue on your dog's hair that remains for many weeks. Studies show that poisoning by some types of chemicals can occur by ingestion of the collar or by the licking of the residue found on the hair. Dog owners who use these products should also be aware of the potential dangers to other household pets and to children.

Flea and tick collars can contain ingredients that can be highly toxic to dogs if ingested. Amitraz and propoxur are two such chemicals, added to flea and tick collars during production. Accidental ingestion of a collar by your dog can result in severe toxicity.

With a skin irritation of propoxur, there may be evidence of redness of the skin, loss of hair, and a constriction of the iris of your pet’s eye.

Other than amitraz and propoxur, another chemical used in topical solutions for flea and tick control and for collars used to eradicate these pests is tetrachlorvinphos, an organophosphate also known to be toxic to your dog’s nervous system.

Flea and tick collar poisoning occurs when a pet ingests a collar or consumes the chemicals that are left on the skin and fur as a residual product. Studies have shown that chemicals that are harmful to both your family pets and children can remain (and are accessible each time the collar is touched) for a few weeks after the collar has been put on your dog. Caution should be used when putting the collar on your dog; wash your hands after attaching the collar and make sure it is secure enough that pets cannot easily remove it, ingesting it accidentally in the process. Studies show that puppies and toy breed dogs, particularly the Chihuahua and Pomeranian, are susceptible to severe poisoning upon ingestion of a flea and tick collar containing amitraz.

When diagnosing poisoning from a flea and tick collar or from the residue left on the hair and skin, the veterinarian will come to a conclusion based on the history and specifics that you are able to provide, if any, and the clinical signs. If you see that your pet is showing signs of a poisoning like loss of bodily movement control or vomiting, remove the flea collar right away, or in the case of ingestion bring the remains of the collar in with you when you go to the clinic or emergency room. Provide the veterinarian with as much information as possible, such as recent illnesses, changes in behavior that you may have noticed, and the approximate length of time that your pet has been exhibiting the symptoms. The veterinarian may order blood tests, urinalysis, and abdominal x-rays but the timing of these tests will depend upon the immediate condition of your dog.

Flea collar poisoning is treated with support therapy and medication. Vomiting may be induced by the veterinary team, depending on the timing and chemical in the collar, and whether your pet is in a depressed state (as there could be risk of aspiration pneumonia). Activated charcoal may be used to bind the poison.

Fluid therapy will likely be started, and your canine companion will be closely monitored. The veterinary team will check at regular intervals, your dog’s blood pressure, heart rate, body temperature, blood markers, and urine production. If your pet is dehydrated the fluid therapy will ensure that he is getting enough liquids. Medication to counteract the effects of the toxicity will be administered as well if possible

If the x-rays have shown the location of the collar in the intestine or stomach (or the absence, meaning the pieces did leave the body with the vomitus) an endoscopic procedure could be considered to remove it. In addition, your dog’s hair will be gently washed to remove all traces of the chemicals released by the flea collar.

While there are risks of toxicity if used inappropriately or eaten, veterinary approved flea and tick collars are generally quite safe if used properly.  With both amitraz and propoxur, the prognosis can be favorable with early treatment. This is why it is so important to visit a veterinarian immediately if you suspect that your dog has ingested a poisonous substance. Your pet may recover, but the length of time it takes for him to get back to normal will depend on the level of toxicity and his state of health at the time of the incident. When dealing with a flea or tick problem, always consult your veterinarian for advice on the best products to use.