Ask a Vet: How Did a Natural Flea Prevention Product Almost Lead to a Cat’s Death?


I hate fleas.

Although I always have claimed to be an animal lover, and fleas are animals, I do not feel any cognitive dissonance about this apparent contradiction. Fleas are horrible creatures. I realize that they fulfill certain roles in the ecosystems in which they reside, but those roles are bad. Fleas cause agony and misery in companion animals. They spread diseases such as feline infectious anemia and bartonellosis (known inappropriately as cat scratch fever, when really it should be called flea feces fever). And let us never forget fleas’ role in the death of one-third of Europeans in the middle ages — fleas are the vector for plague.

Over the years I have treated many cats who died or nearly died as a result of fleas. Feline infectious anemia, caused by a bacteria in the Mycoplasma genus, has led to the near-demise of many a patient. And I have seen many cats nearly die (and a few actually die) from a different type of anemia caused by fleas. These cats had such heavy flea burdens that the blood sucking parasites sucked them near or to the point of death.

After an incident at work a few weeks ago, I have a new reason to hate fleas. They may lead to life-threatening intestinal obstructions.

Photo of Dr. Eric Barchas by Liz Acosta

A cat was brought to my clinic with a history of vomiting and weight loss. The owners had been struggling with a severe flea infestation in their house. They had used a natural product that, like all natural flea control products I’ve encountered, was absolutely ineffective.

Blood tests showed no cause for the gastrointestinal symptoms. Radiographs (X-rays) also did not provide an answer. An ultrasound of the abdomen, including the intestines, was performed. It showed a foreign object lodged in the intestines.

How, one might ask, could a foreign object show up on ultrasound but not on radiographs? Certain soft items such as fabric, hairballs, and some plastics are “radiolucent,” or invisible on X-rays.

The cat was rushed to surgery, and the foreign body was found within the intestines. The surrounding intestinal wall was devitalized and in the process of dying; fortunately, it had not yet burst open. The affected section was removed and the remaining sections of intestine were sutured back together.

While the cat recovered from surgery I opened the affected section of intestine to determine the nature of the foreign body. It was a hairball. The cat had nearly died from a hairball.

A cat coughs by Shutterstock

Although many people believe hairballs are normal in cats, in fact they are not. Hairballs don’t just happen. All cats (except for the hairless breeds) groom and swallow hair, and their systems are designed to move the hair through the intestines and out the rear end into the litter box.

Recent research has shown that a very significant number of cats who develop hairballs suffer from problems with their digestive tracts. These may among other things include inflammatory bowel disease, intestinal motility disorders, pancreatitis, and a nebulous condition called triaditis. The cat in question had no evidence of these disorders on any of her diagnostics (and she underwent the ultimate diagnostic event — exploratory abdominal surgery).

So why did the cat’s nearly fatal hairball develop? It is possible that a very mild (too mild to be observable on ultrasound or during surgery) case of pancreatitis or inflammatory bowel disease contributed to the matter. But in the end I wound up suspicious of her flea infestation.

The owners reported that the cat had been frenetically grooming during the time of the infestation. The cat’s hair was sparse and barbered (which is a way of saying that she had been biting the hair off with her teeth). I theorized that over-grooming and subsequent excessive hair consumption because of the flea infestation had contributed to the formation of the terrible trichobezoar.

Cat scratching by Shutterstock

Although I always have had bad things to say about natural or alternative flea preventatives, I should confess that these products are not alone in their inefficacy. Frontline Plus was applied in our hospital to the cat in question. (She could not take an oral preventative before or immediately after surgery because of her intestinal issues.) Twenty-four hours later she was still crawling with fleas that appeared to be alive and well.

Fortunately, 12 hours after surgery the cat’s intestines were sufficiently healthy for oral treatments. She received a dose of Capstar, which did the trick.

I counseled the owners extensively on how to address the home infestation. One stage of the flea life cycle, the pupa, is immune to all medicines, flea bombs, and other treatments. There will be millions of pupae in carpets, on bedding, and in every crack and corner by the time there is an active and visible flea infestation in the home. I recommended discarding bedding and cleaning as much as possible, but I warned the owners that millions of pupae would remain. The best option in such circumstances is to use an effective product (for now, Comfortis still seems to work very well) simultaneously and consistently in all pets in the house. After several months all of the pupae will have hatched into adult fleas that will have been killed by the effective preventative.

The cat in question went home to finish her recovery. But don’t let this happen to your cat. Stay ahead of the fleas with an effective preventative.

Other stories by Dr. Eric Barchas:

Got a question for Dr. Barchas? Ask our vet in the comments below and your topic might be featured in an upcoming column. (Note that if you have an emergency situation, please see your own vet immediately!)

2 thoughts on “Ask a Vet: How Did a Natural Flea Prevention Product Almost Lead to a Cat’s Death?”

    1. Hi there Kathy,

      Thanks for reaching out! We suggest contacting a vet with this question. You can also reach out to Dr. Barchas through this link:

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