Can Fleas Make Cats Aggressive?

Oh, no, there's another one!
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If crawly pests have taken residence on Kitty's skin, you can expect some moodiness to come around too. After all, who can deal with all the itchiness and still keep a purr going? Fleas can cause some behavior and mood changes -- until you deal with the problem.

Mood Changes

You can't blame Kitty for becoming irritable if he has a flea infestation. And who can blame him? After all, all that scratching and itching is bound to drive anybody crazy. According to Cat Channel, cats with a serious flea problem might become restless and agitated. Although they might not necessarily be aggressive, they could be on edge, ready to dart off or react suddenly to things going on around them.

Behavior Changes

Cats with a serious flea infestation can become obsessive groomers. This can take the form of repeated licking or it can cause Kitty to bite or scratch himself until he bleeds. In a way, this self-aggression is the result of desperation -- the itching simply becomes too much to handle and anything, including hurting himself, is better than enduring it.


If the flea problem is not addressed, it can lead to anemia in cats. As anemia progresses, it can cause Kitty to feel really tired and lethargic -- especially if he's really or really old or has a previous health issue. This would be the opposite of being aggressive: a cat who's too tired or too weak to react to things around him.

Sleeping Habits

A cat who has fleas might suddenly have a change in sleeping habits. For starters, he might have trouble sleeping at all -- especially if he has so many fleas that the itching is too much to bear and won't let him relax and fall asleep. Because fleas are more likely to hide in rugs and carpeted rooms, you might suddenly find Kitty avoiding any soft surfaces -- and instead choosing to sleep on tile or hardwood floors.

Always check with your veterinarian before changing your pet’s diet, medication, or physical activity routines. This information is not a substitute for a vet’s opinion.

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