Monday, December 4, 2023


Pests on your pets: The best meds to use to keep ’em off!

Ewwwww, pests on your pets like fleas, ticks and mosquitoes are gross and annoying. Your cats and dogs are exposed to these every day, even if they are indoors. When your vet urges you to keep your pets on flea and heartworm preventives, they are looking out for your pet’s long-term health and not just preventing itching and irritation. 

How do they make my pet sick?

Fleas, ticks and mosquitoes carry dangerous parasites – one bite can infect your cat or dog with a bug that you won’t even know is there until your pet gets sick. Fleas carry tapeworm eggs and both fleas and ticks carry a variety of blood parasites such as Hemobartonella,  Cytauxzoon, Hepatozoon canis, Anaplasma, Erlichia and Babesia. Ticks carry the bacteria Borrelia burgdorferi, which causes the dreaded Lyme disease. Many hunters are familiar with tick paralysis – ticks carry a toxin that can lay a healthy coon dog flat. Weird sounding names, but all of these can cause life-threatening anemia, respiratory disease, lameness and other serious illnesses.  

The pesky mosquito was often in the news – the Zika virus threatened to close the last Summer Olympics. In most regions of the U.S., mosquitoes carry a very dangerous worm – the heartworm. When a mosquito bites your dog or cat, it transfers the larvae into your pet’s blood where it travels to the heart and matures and replicates. After a period of time, when the heart fills up with worms and can no longer function, your pet dies of heart failure. It’s not pretty.

Photo Credit: American Heartworm Society

Medications that work!

Luckily, there are medications that can prevent these infections. Over the past decade, preventives have been developed that are safe and effective. Dusting your pet with toxic “flea powder” has been replaced with oral and topical medications. I consider these monthly treatments an insurance policy that can not only protect your pet but also save you a lot of money; a blood test for flea- and tick-transmitted diseases can cost up to $250, and then there is the cost of treating the disease.

A $15 per month pill or spot-on is a better option. Not all medications are created equal – some don’t work and some are downright dangerous. The new effective products are very specific in killing the flea, tick or worm; many older products are merely pesticides. Pesticides may be toxic to your pet and you if you come into contact with it.  

This product will kill your cat!

A very important thing to remember is NEVER USE A DOG PRODUCT ON A CAT! Look at the label carefully because some dog products can be FATAL if used on a cat. There are many products that you can buy at Walmart or even at the grocery store that may not work or may be dangerous to use on your pet (there is not a lot of regulation of pet products). Please consult your veterinarian about which products to use.

I am a big fan of the “multi-products” such as Revolution and Advantage Multi. These products work on fleas, heartworms, some intestinal worms and ear mites. There are no products that do everything. Frontline is not effective against fleas in North Carolina, but it is against ticks. Bayer now makes the Seresto collar that, unlike the old flea collars, actually works against both fleas and ticks for eight months. If using a Seresto collar, you will need to use a heartworm medication and use a general dewormer regularly to get full coverage. 

If you are unlucky enough to have a flea problem in your home or RV, it is important that you not only treat the pets but you must also treat the environment. Fleas lay millions and millions of eggs. Diligent cleaning and treating carpets, bedding, and floors will help keep them from multiplying. Your dog or cat, with their medication on board, is a walking exterminator – when the flea bites the dog, it dies. 

Flea poop = bad news

Oh, and by the way, flea poop can cause a nasty blood infection in people. It’s commonly called Cat Scratch Disease (CSD), but it also can be caused by dog scratches too. The nasty bug is a bacteria called Bartonella henselae. A cat or dog who has fleas scratches itself lodging flea poop under its nails. If your pet scratches you and breaks the skin, the bacteria infects your tissues. It can cause a minor infection or it can be more serious and spread via your blood making you very sick. 

Lastly, fleas are very diligent and patient parasites – their eggs can lay dormant for long periods of time waiting for a warm-blooded host to wake them up. It is not uncommon for families and their pets to move into a new home only to set off a “flea bloom” – the previous tenants had pets with fleas leaving behind millions of eggs. Winters can discourage fleas and mosquitos, but fleas can live under porches, in sheltered sheds and on the squirrels that hop onto your deck. These are reasons I recommend keeping your pets on flea preventives all year long. 

Scruffy is always protected from parasites!

Ask the Pet Vet

Fido feeling under the weather? Fifi been having some tummy troubles? Worried about ticks? What’s better, wet food or dry food? Wondering how to clip your pet’s nails? Ask veterinarian Dr. Karel Carnohan your questions over on her forum


Karel Carnohan DVM
Karel Carnohan DVM
After a long career in finance, Dr. Carnohan returned to school and graduated from the Kansas State College of Veterinary Medicine at the tender age of 50. She has worked in Canada and the United States in both small and large animal medicine. She retired in 2020 after selling her feline-exclusive veterinary practice in Asheville, NC. She currently lives in the Coachella Valley, CA and travels in her Newmar toy hauler with her multiple cats. Her interests include hockey (having played for many years), the brown bears of Katmai, cats and scooping litter boxes.



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Neal Davis (@guest_229277)
8 months ago

Thank you, Karel! We use NexGard for fleas and ticks. It seems to work, but our dog is an inside dog who ventures outside for walks and potty breaks. Oh, and sometimes he almost goes outside, but really just wants the glass door opened so he can see better.

Last edited 8 months ago by Neal Davis
Bob R (@guest_229243)
8 months ago

If an RV (or the home, for that matter) has a flea problem, you can also use 20 Mule Team Borax powder. Spread it on rugs and – especially – in cracks and seams of any and all upholstery where fleas like to hide. Despite their reputation as a pestilence, fleas are meticulous. When they get the powder on themselves, they ingest it when cleaning themselves. The crystal nature of the Borax slices up their insides. So long as you keep it dry, it can stay in place for years. Borax works great against fleas.

Marilyn M (@guest_158494)
1 year ago

For over a decade I’ve been giving my dogs Nupro. It’s a glucosamine supplement powder that stinks to high heaven that when mixed with a bit of water in their dry food makes a gravy – the girls love it! So their joints are happy which makes my wallet happy. But an added benefit (which is awesome) is it stops ticks and fleas! In all the years only 1 flea and it was just crawling on the top of the fur, not trying to latch on.

Dr. Mike (@guest_229206)
8 months ago

Making a necklace of garlic and doing a specific dance around the pet also works! This is a joke from a fellow veterinarian. I’m sure Dr. Karel gets it.

Dr. Mike (@guest_229216)
8 months ago
Reply to  Dr. Mike

Please use products that your veterinarian can provide to you. They are safe and effective.

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