Why Does My Cat Go Crazy After a Flea Treatment?

 You might be asking yourself — Why does my cat go crazy after a flea treatment? And while that’s a common question, the answers vary greatly.


More often than not, the cat will ingest flea medication by accident, and its body will react. That will result in flea treatment poisoning, or flea collar poisoning if you’re using a special serum-filled collar. 


Other times, your cat might simply have an adverse reaction to the serum because of a weak immune system. You might be the one at fault, as well; if pet owners use dog flea medicine on cats, or adult cat medicine on kittens, their pets are likely to behave erratically after their treatment. 


Other common reasons behind crazy post-flea treatment behavior include fear, anxiety, a reaction to the flea infestation, and even other health issues unrelated to flea bites. 


Why Does My Cat Go Crazy After a Flea Treatment?


Why does my cat go crazy after a flea treatment? This is a question I’ve heard crop up so many times among so many different cat owners. I was even more surprised that there weren’t enough articles out there addressing the problem. If you were to type the phrase why does my cat go crazy after a flea treatment into a browser, you’d get precious few results. 


As a cat lover myself, I felt like this article needed to be written. It’s not uncommon for animals, like humans, to suffer side effects after an important medical treatment. After all, improper medication use can lead to problems that are even worse than the condition you originally wanted to treat. So, if you want an answer to the why does my cat go crazy after a flea treatment conundrum, keep reading.


The Importance of Flea Treatments


Fleas are external parasites. They attach themselves onto the body of a host, usually a mammal, and bite their flesh. Most often, a flea will simply jump up from its natural habitat and attach itself to the host. However, animals (as well as humans) can also pick up larvae while walking through tall grass or wooded areas. The larvae will then develop on the host’s body until they mature into adult fleas.


If a flea bites a cat, it can cause itching. The cat will frantically scratch at the bite area to get rid of the itch. This scratching alone can lead to numerous problems, which include loss of fur, swelling, painful sores, and an infection of the bitten area. But the fleas are also carriers of various other parasites. 


For instance, flea larvae tend to feed on tapeworm proglottids. Each proglottid stays inside of the larva during the pupal stage. Once a cat ingests the pupa, the tapeworm can manifest inside the cat and continue its life cycle.


Flea-Related Diseases

Like many other carriers, fleas are responsible for some of the most serious diseases that affect mammals, including cats. A sample of those diseases includes:


  • Calicivirus
  • Feline leukemia virus or FLV
  • Rickettsial diseases 
  • Bartonellosis
  • Flea allergy dermatitis
  • Plague
  • Tapeworm infection


Most of these conditions can lead to life-threatening issues for the cat. That’s why it’s incredibly important to conduct proper flea treatment of your feline pet.


How to Perform the Treatment


Deworming and anti-flea treatments are crucial for your cat’s safety. Administering them is a bit uncomfortable for the cat, however. You have to take a pipette and apply the anti-flea serum onto the nape of your cat’s neck. 


The process is rather simple:


  • Have someone help you by holding the cat in place
  • Part the hair on your cat’s neck and expose the skin underneath
  • Squeeze out the serum onto the area and gently rub it in
  • Make sure that the serum is only applied at the neck, where the cat can’t lick it.


Most of these serums will provide protection for about 3–6 months. In other words, you won’t have to treat your cat very often, which saves you lots of time and effort.


So, Why Does My Cat Go Crazy After a Flea Treatment Is Done?


Unfortunately, lots of things can go wrong when you’re treating your cat for fleas. Sometimes, it all comes down to human error, while other times, it’s the cat’s behavior. So, in order to help you pinpoint the cause, I’ve compiled an overview of the potential reasons below.#


Flea Treatment Poisoning

Anti-flea products come in all shapes and sizes. Usually, pet owners use powders or shampoos and rub them into their cats’ fur. Other options include lotions and sprays. 


Each of these types of products has one fatal flaw, however. When you apply them onto the fur, the cat can ingest them by accident and get flea treatment poisoning. In fact, it doesn’t even have to do it consciously. For example, if I were to get an anti-flea spray, I could accidentally spritz some of it into my pet’s mouth.


And it doesn’t end with ingesting the product, either. If you were to use too much of it, the chemicals could affect your cat through skin contact alone.


In order to spot flea treatment poisoning, observe your cat and see if it exhibits the following symptoms:


  • Facial and/or ear twitching
  • Vomiting
  • Lethargy
  • Diarrhea
  • Seizures or muscle tremors
  • Excessive drooling
  • Agitation or anxiety
  • “Drunk walking.”


There are even cases of cats dying from flea treatment poisoning. However, those are few and far between.  


Flea Collar Poisoning

Sometimes, instead of applying a solution, pet owners buy flea collars for their cats. These collars can be effective, but they are dangerous if you don’t put them on your pet properly or if your pet licks them. 


An average collar contains lots of harmful chemicals. Some of them include:


  • Organophosphates
  • Amitraz
  • Pyrethrin
  • Carbamates
  • Pyrethroids


If any of these chemicals make it into your cat’s digestive system, they will cause flea collar poisoning. Therefore, if you notice that your cat is behaving strangely, remove the collar at once and contact the vet. The symptoms are the same as the ones for regular flea treatment poisoning, with the addition of dilated pupils and a drastic change in blood pressure. 


Ingesting Medicine by Accident


I’ve already covered ingesting products like powders, sprays, etc. Without a doubt, applying a gel on the nape of the cat’s neck is the safest option since it cannot reach that spot when it’s grooming itself.


However, there are still ways in which a cat can accidentally taste the anti-flea serum. For instance, if you leave the pipette lying around, the cat can look for it and give it a lick. The same can happen if you don’t dispose of a used pipette properly, or if you try to caress your kitty without washing your hands after applying the serum. 


Weak Immune System


Cats are similar to other animals (and humans) in various different ways. For example, each cat is allergic to something, and they all have different immune systems. In other words, one cat will have no problem with one type of processed meat, while another one might have severe health issues after a taste. 


The same goes for medication. Before you decide which brand of anti-flea serum to use, consult your vet about it. The product might contain ingredients that can harm your cat, or worse. 


Using Dog Flea Medicine by Mistake


Sadly, lots of pet owners like to cut corners when taking care of their cats. So, instead of buying a proper anti-flea medicine for cats, they get a dog-only solution. 


This is not only lazy on the part of the owner but also extremely dangerous. Most commercial anti-flea medications for dogs contain pyrethrin and pyrethroids. As we saw earlier, these chemicals can cause poisoning if a cat comes into contact with them. It should go without saying, but I’ll stress it anyway — do NOT use dog medication on a cat, ever.


Using Adult Cat Medicine on a Kitten


This section also falls under poor pet care. Newbie cat owners usually don’t pay attention to the label, whether it’s food, medication, or bedding. They see a picture of a cat and automatically buy the product without giving it a second thought. But taking care of a cat is not always the same as taking care of a kitten.


Kittens are delicate and frail compared to adult cats. They are still developing, so you can’t use any adult products on them. Even a regular dose of an adult cat anti-flea serum could harm the kitten by poisoning it. So, before buying anything, consult the vet. 


Why Does My Cat Go Crazy After a Flea Treatment? — Other Potential Causes


Anxiety and Fear

Put yourself in the cat’s position. Your owners took you to a vet’s office, a place you don’t know and have never been to. And soon after, someone unfamiliar to you is putting something cold and slimy on your neck while your owner is holding you down. 


That, in and of itself, is enough to cause fear and anxiety in cats. So, if your cat goes a little crazy after the flea treatment, it’s probably still startling from the procedure itself. In time, it will calm down and behave the same as usual.


Other Health Issues

It’s not uncommon for a cat to have fleas and suffer from another condition at the same time. For example, your pet might have gastrointestinal problems or an infection. 


Both of these conditions can cause the cat to behave erratically. If you suspect any other health issue, take the cat to the vet and have it examined.


Reacting to the Infestation


Having fleas is not pleasant at all. Cats who are infested with them tend to act erratically even before you administer the serum. That’s why it’s not uncommon for them to continue to act that way after the anti-flea treatment. All you have to do is give them time, and they’ll switch back to their default settings soon enough.


Why Does My Cat Go Crazy After a Flea Treatment? — A Few Final Thoughts


Treating a cat against fleas is as important as any other procedure. But as an owner, you have to be careful and approach the problem the right way. Keep in mind that you should always consult the vet and make sure that you get the right product. Hopefully, the dreaded Why does my cat go crazy after a flea treatment question never has to cross your mind again. 

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Michael Grover

About Me I have been a pet owner for most of my life. I am now retired and spend my days writing about problems relating to cats, dogs, and funeral poems. I am passionate to stop animal cruelty in any shape or form. My passion is to help people like you identify behavior problems in cats and dogs. That is what I do. Over the years of my life, I have always kept cats and dogs. About 4 years ago I retired and found I had a lot of time on hands so I started to write all about dog and cat problems. It was suggested to me that I should start up a website and publish my words to help people with their pet problems. I am still writing every day and hope you find my articles useful. Regards Mike Grover

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