Dear Dr Fox: We have two senior springer spaniels with a sensitivity to fleas, and I have reviewed your articles on flea prevention for dogs. We are currently giving them Bravecto as a flea treatment. Living in New Jersey, we only dose them twice per year.

While we don’t like using this, it is the only preventative that has not caused side effects (at least, that we can see). Frontline and Advantix caused vomiting and lethargy for a few days after application.

We almost lost our older girl to a hot spot that became infected, which our vet believes was caused by a flea bite. Any other suggestions? — B.H., Trenton, New Jersey

Dear B.H.: Many dogs get by OK with seasonal use of Bravecto, but I would never use it on my dog here in Minnesota. In India, we had to use Frontline all the time, and at least one dog had seizures.

I would rely on a flea comb after each trip outdoors; check for ticks at the same time, especially between the toes and ears. Best to avoid brushy areas where there could be ticks and fleas from other animals.

As a preventive measure, make a “tea” of one sliced lemon boiled briefly in 2 cups of water. Let cool and store in fridge. Apply to each dog with a sponge, getting the underbelly, legs, under the neck, and along the back, head and ear tips. This will repel mosquitoes, fleas and ticks. Essential oil of eucalyptus lemon is also excellent, and you can make a spritz out of it with water, but cover their eyes when applying.

These natural herbal products have been used effectively for centuries but their use has been supplanted, and even outlawed, by the big pharmaceutical companies, which are in the human and animal health business primarily to make a profit. Their reticence to take action and recall or relabel drugs that have adverse side effects is a matter of public record.

As for Bravecto and other insecticides widely sold in most veterinary clinics and some grocery stores, I am of the same opinion: These chemicals should only be used as a last resort. Eventually, insect tolerance and resistance to these insecticides will evolve, and using them year-round as prevention will accelerate this process.

Also, these products will not prevent biting insects from transmitting allergens, Lyme, heartworm and other diseases, as they only kill or sterilize the pests after they have bitten and fed off your dog or cat. For details, check my website (drfoxonehealth.com) for the article on this issue, “Companion Animal Risks of Flea and Tick Insecticides.” Dogs treated with such chemicals should be kept out of streams and lakes to avoid harming the life therein.

Dear Dr Fox: My 8-year-old neutered tabby, Samson, has been coughing up fur for some time, and I find bits on the floor. In the early evenings, especially, he starts to groom himself, licking and pulling out bits of fur. Later, he coughs and hacks something terrible. The veterinarian sold me some cat food that’s supposed to help stop furballs, but after two months, it’s made no difference, and he does not like to eat it.

What will help? — N.McC., Fort Myers, Florida

Dear N.McC.: It can be very distressing living with a cat suffering like yours, as I know from personal experience.

The latest instance was with our rescued “feral” cat Fanny, who left small tufts of fur around the house for several weeks. This stopped when she settled down and became attached to our dog, at which point she even allowed me to touch her when she was in her bed for the night.

My first question for you to consider is whether Samson is under some emotional stress. What, for instance, is going on in the home when he starts to pull out his fur? Either make it a quiet time or engage him in play to distract him.

Another two possibilities that your veterinarian should have discussed with you are food allergy/intolerance and thyroid disease. If a change in diet to one free of additives, fish, corn and soy does not help, then a blood test for hyperthyroidism would be in order.

Help veterinarians help animals worldwide: The mission of World Vets, a nonprofit based in Washington state, is to improve the health and well-being of animals by providing veterinary aid, training and disaster relief worldwide. Your donations will make a big difference for animals in many countries, as volunteer veterinarians donate their time and expertise in poor countries and communities where a few dollars make a big difference for animals in need. For more details about this excellent veterinary initiative, visit worldvets.org.

Visit Dr. Fox’s website at DrFoxOneHealth.com.