Dangers of Spot-On Pesticides for Fleas and Ticks

If you don't think it's worth it to stop using pesticides on your dog for flea management, consider these compromises as viable options.


Some people will never give up their use of spot-on pesticides, despite the health risks to themselves and their dogs. I know you’re out there, and I understand. Perhaps you have a dog with a flea allergy so severe – a dog who scratches and chews himself so badly that he develops severe hair loss, “hot spots,” and/or worn teeth – that taking time to reap the benefits of an integrated pest management plan seems unthinkable. Giving up these fast, effective flea-killing products may seem like a step back into the dark ages.

I don’t think it has to be that hard; there is certainly some middle ground you can explore, something between using spot-on products monthly and not using them at all. Consider the following as a compromise.

1. Don’t use flea-killing pesticides as your only form of flea control. Continue to use integrated pest management techniques such as frequent vacuuming, washing the dogs’ bedding weekly, and using flea combs and traps to monitor the flea population.

2. ALWAYS read the directions for the products and follow them explicitly. Many chemical product injuries result from misapplication. If a label indicates you should not administer the product to dogs of a certain age, or to dogs who are sick, don’t use the product. Don’t guess your dog’s weight to determine the dose; ask your vet if you can bring your dog into the clinic to weigh him. It’s important that you use only the correct amount of the product and no more.

3. Although the makers would like you to regard the monthly application of their products as a necessary monthly chore, it may not be needed that often. In many homes, once fleas have been eradicated, it may be months or even years before a new population is somehow introduced.

Try discontinuing use of the products, and keeping a close eye on all pets in the house. Check each animal for fleas visually and with a flea comb every few days. Don’t use the spot-on products as long as all animals appear flea-free.

4. Stretch the period between applications. I know people who treat their dogs two to three times a year with great success.

5. Make a note on your calendar every time you apply a spot-on product to your dog – but not to remind you to do it again next month! Do it so you can keep track of the total exposures you have subjected your dog to over time, and so you can track any reactions he may exhibit. Best of all, devote a small notebook to keeping a complete health history for your dog, noting use of flea treatments, major diet changes, veterinary treatments, and any unusual reactions you may see.

6. Try to limit the number of ways that new populations of fleas can be introduced to your home. I don’t take Rupert, my severely flea-allergic dog, to my friends’ homes because most of them have dogs, and in the mild climate of the San Francisco Bay area, most of us struggle with fleas.

More difficult is the issue of my friends’ dogs coming to my house. Although I edit this magazine from my home, and I love my friends’ dogs, too frequently, Rupert would break out in paroxysms of itching and chewing after dogs visited. Frequently, I could never find a flea on him; I assumed it was probably a single flea bite that set him off. Finally, I had to ask my friends to either leave their dogs at home or leave them in the car when they came over. And when it is necessary to have a dog over (boarding relatives’ dogs over the holidays, having the neighbor’s dog come over to relieve her separation anxiety), I check him or her for fleas before they get to the front door! If the flea comb turns up fleas, into the bathtub they go.

7. Say your situation displays all of the signs of the worst-case scenario: You live in a mild climate, where fleas are a year-round problem. You have multiple dogs, and you regularly take them to dog parks, daycare, beaches, or other areas where many dogs congregate. Maybe you have friends who bring their dogs over, too, so introductions of new fleas are more or less constant. The only way you have ever been able to achieve a flea-free household is to use spot-on products on your dogs.

If this describes your household, consider taking all of the following steps: Implement all the integrated pest management techniques you can (don’t rely on chemicals alone for control); extend the time between applications as long as you can; and treat healthy adult dogs more frequently than very young, old, or sick dogs. For example, treat the two healthy dogs and skip the immune-compromised individual, concentrating every nontoxic remedy that exists on that dog.

8. If your dog ever shows signs of a reaction following administration of a spot-on product, take your dog to your veterinarian. Report the reaction to the Environmental Protection Agency (EPA), which tracks adverse pesticide experiences. You can also report the incident to the product manufacturer; pesticide makers are required by federal law to forward any adverse experience reports to the EPA.

Another good resource is the National Pesticide Information Center, which provides information on recognizing and treating pesticide poisonings, and can make referrals for investigation of pesticide incidents.

Signs of pesticide poisoning include external reactions such as redness, swelling, or blistering. Signs of internal injuries include shortness of breath or rapid breathing, drooling, nausea, vomiting, diarrhea, excessive fatigue, or muscle twitching. If your dog displays any of these signs following pesticide application (even a week or weeks afterward), discontinue use and consult your veterinarian. And – seriously – don’t use that sort of product again.


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