Dealing with fleas is an annoying problem, but are spot on flea treatments bad for your chihuahua?

Monthly plans

A lot of chihuahua parents believe they are doing the best for their chihuahua by using monthly ‘spot on flea treatments’. By spot on flea treatments I mean any chemical flea treatment that is applied topically to your dog’s skin.

It is so ingrained in us that this is the right thing to do that many of us are on monthly plans at the vets that include flea & worm treatments and ‘booster’ vaccinations.

Firstly, booster vaccinations are not required read ‘Are we Over Vaccinating Dogs?’ But this article is about chemical flea control, so I’ll move on.


How do spot on flea treatments work?

The insecticide in spot on flea products blocks the adult flea’s nervous system and the flea should die within 24 hours. This reduces its opportunity to lay eggs.

The insecticide is mixed with a carrier oil that spreads over the skin and is absorbed into your dog’s bloodstream, it also kills intestinal worms and lungworms. If this doesn’t work, it may be worth checking out 25 Incredibly Easy Home Remedies for Worms in Dogs. It’s best to treat the issue before it becomes life-threatening.

Given the job it does, it is easy to see why so many pet owners will reach for their monthly flea control without giving it another thought.

The downside

I stopped using these products some time ago when I noticed an adverse reaction in Mika after the application. He would be unwell, vomit and shake.

Research shows that this is a common reaction to the chemicals in these flea control products, along with redness of the skin where it is applied. Reactions vary in intensity, but it has caused fatal seizures in dogs.

There are three main chemicals Fipronil, Imidacloprid and Pyrethrins in spot on flea products. According to Dogs Naturally Magazine these chemicals have arrange of side affects on your dog, from liver and kidney toxicity, thyroid cancer, heart disease. It was a long list, so I have put a link to the article below.

According to experts, topical chemical flea control contributes to the rise in canine cancer. It also contributes to allergies in dogs.

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Why chihuahuas & small dogs are more at risk

The application of topical flea control products can cause an immediate adverse reaction in your dog, one of the main reasons being that the dosage parameters are so wide and vague. The under 5 kgs dose instruction can be way over the top for a dog that weighs half that.

Do short coats even get fleas?

I have noticed something strange since we had Arlo who is a short coat. He never seems to pick up fleas. The other two, Mika and Minnie do pick the occasional jumper. But Arlo, never. Looking at his coat it is so much denser that the long haired dogs it is so thick at the base. So is this just not hospitable for a flea. I would love to know your thoughts.


Healthy Pets Mercloa writes:

  • Most adverse reactions were seen in dogs weighing between 10 and 20 pounds. (4.53 -9.09 kg)

  • Reactions in mixed breed dogs were most commonly reported, however, the Chihuahua, Shih Tzu, Miniature Poodle, Pomeranian, Dachshund, Maltese, Yorkshire terrier and Bichon Frise seem particularly at risk.

  • Products containing cyphenothrin and permethrin were especially problematic for small breed dogs.

  • Most incidents occurred in dogs under three years old, likely at their first exposure to a spot-on product.

  • Adverse reactions for both dogs and cats were primarily skin, GI tract and nervous system related. Skin reactions included redness, itching, hair loss, sores and ulcers.

  • Gastrointestinal symptoms included vomiting, diarrhoea and salivation.

  • Reported nervous system symptoms included lethargy, nervousness, ataxia (movement problems), tremors and seizure.

Only dealing with mum

Fleas are a nuisance and need to be dealt with, but the other problem with many spot on flea treatments is they are only dealing with the adult.

The adult flea is the tip of the iceberg. Killing the eggs before they hatch must be the target. Because once they are in the carpet or dog bedding, as soon as the product wears off they will hop straight back on again.

But again, don’t reach for the chemicals and spray them all over your house, they can be bad for you and your family contributing to migraines, asthma and eczema.

Go natural

We have several articles on dealing with fleas in the home and natural ways to keep your dog flea free.

But essentially, neem oil, diatomaceous earth, a good steam cleaner, apple cider vinegar and a hot wash for bedding should get you started on the path natural to flea control.

Article from Dogs Naturally Magazine

Please be aware that putting canine flea products on a cat can kill your cat.