Let me start by saying, im a vet tech. Ive seen this product work well for cats that are aggressive at the vet. Ive seen it turn cats that previously needed full sedation/anesthesia in order to be examined, into cats that were just grumbly/hissy but we were able to do everything we needed without the sedation. As a tech we expect cats to be grumbly/hissy so that's totally something we can work around as long as they aren't lashing out/attacking or significantly struggling to the point that it's detrimental to their wellbeing. At our office we dont like to give sedation/anesthesia unless we have to because it can be hard on the body. So this jacket is a real winner for the cats that it works for.

My cat on the other hand was a no go. I bought this for my cat for a car trip. When I moved cross country she meowed and was stressed the entire 3 days, even with anxiety meds for the car ride. She has to go on another 5 hour car ride so I thought this would help. After putting it on her I couldn't even get her into the carrier because she was flipping out. Literally, flipping and flopping all over and kicking. I took it off and she went into her carrier no problem, so we did not use it because of that. And we got to listen to meow-cat radio for another 5 hour car trip.

I've been skeptical of thundershirts for years, especially for cats. But when I caught this one on sale, I decided to experiment -- fully intending to return it if I did not see results. I expected nothing to happen and my 15-pound male kitty to hate it. I was not going to get my hopes up.

Well, I admit when I'm wrong. And this time, for my kitty, I have been wrong so far.

I experimented with the shirt for a few days. He didn't like having it put on, and did not like moving around in it (he walked low, belly close to the ground) and seemed generally displeased.

But then he laid down next to me on the couch and flexed his paws, purring. He stayed that way for a while.

The next day, he still was unhappy getting it on and moving around in it, but eventually laid in his bed, and later mine, and was content and calm.

I should say now, I did not purchase this for regular use around the house, but rather for travel. I wanted to see if it lived up to the hype and I could avoid the light sedation I had had to use in the past for hours-long road trips or flights.

The true test came on a 6-hour drive and return trip. I put the shirt on him, which he still does not love, put him in his carrier and buckled it in for the drive. He was quiet, calm and relaxed the entire trip. Even when sedated, he sometimes meows or shuffles anxiously in his carrier. None of that this time. And when we arrived at our destination, he had none of the grogginess or disorientation that can come with sedation. He was perfectly alert and ate/drank/used his litter box normally.

It was much the same on the return trip. He relaxed on his side and was perfectly alert, or napped, the entire 6 hours. He's used to traveling but has never done so well.

Maybe it's a coincidence. Maybe not. This was just one road trip for us, but based on the results I saw, it was worth the price I paid (when I caught the shirt on sale).

I purchased the large cat size and it fit my guy with room to spare. It's made of relatively soft, slightly stretchy material. I am a little concerned that the stitching will not hold up overtime. It's not reinforced and the material is not very thick, so durability is a bit in question. It's not the easiest to get on/off because of all the velcro, but once on, it is secure.

I was also concerned with it being so snug and becoming uncomfortable for him, but he displayed no signs of discomfort or distress beyond initially having it put on. I doubt that will ever change, though.

So take this all with a grain of salt -- all cats are different and what works for one will not work for another. But this worked for us and I'm happy with my purchase. I would recommend other cat owners give it a try, so long as you check ahead of time and know whether or not you can return it if it does not work for you.

UPDATE: After two years of using this thunder shirt for my kitty, mostly for long road trips (think 5+ hours), I still highly recommend it for all the reasons I listed, it still works just as well as I described and it has held up over time. Again, every cat is different but I highly recommend this shirt. I'm even considering purchasing a backup.

I bought a large for my 12lb cat. It's easy to get on. It calms him down almost instantly and stops him from attacking my other cats.

This really works for my anxious cat. Helps him a lot with stressful situations and on car rides. It really is like magic, even without adding any relaxing Feliway pheromones on the designated patch"” I find the Thunder shirt alone works well. I would give this 5 stars were it not for the fact that it shrank after I hand washed and line dried it. At the $20 price point this is currently at, that's fine, but not at the $40-50 price I paid for it two years ago. Since it was on sale for $20 I went ahead and got a replacement and am thinking about buying a back up in case the price goes up again. Anyway, I removed one star bc of the shrinkage "” otherwise it is really effective. If you're on the fence, just try it. I was skeptical and pleasantly surprised!

Quick backstory:
-My orange cat is Sammy, he's two now, had him for about a year and a half, always happy and playful but developing fear of noises and things like that.

-He was so overly playful I decided he needed a friend and after a couple months looking around I got a hyper little 6 month old kitty who is nice to everyone, cats and dogs included.

-Sammy did not like her, however, and it took some time getting used to but they play together and are great friends.

-Now, problem is Sammy was so stressed from this new cat that he lost a ton of weight(I was scared for him and made sure to get all sorts of blood tests and things like that, he's fine physically). And on top of the weight loss he was also extremely anxious and scared of everything. Literal scaredy-cat.

-I did lots of things to try to chill him out but the pheromones did pretty much nothing(except for a spray one I use in his crate when he gets brought to the vet, which works well, but only in the crate).

-I always saw dogs wearing the anxiety vests and they looked like they worked pretty well. At this point I'm already thousands of dollars deep in medical testing and pheromones and I constantly have to be careful not to scare Sammy and stress him out further, let's try a vest.

-It WORKED the first wear but it works even better after a few more times. The instructions were pretty much to feed your kitty a few treats on the folded up vest so they associate it positively with food, then lay it on their back without strapping it on and let them walk around till it falls off(I did this twice)-all along Sammy seemed very unphased. I fed him about 5 treats up till now-any time he came into contact with the vest- and I then strapped him in. It was easy but I have well trained cats who (honestly) have never scratched me out of anger- sometimes accidentally during play but still rare. So this might not be super easy for everyone. Once I got him in it he did not do the flop that everyone talks about. He's psycho for the laser pointer so I had that out to distract him. Other cat locked in room so that he didn't stress out any. We played about 10-15 minutes and he was only confused two or three times(backing up like something was on him) and I just distracted him with play. Took the vest off after playing, no struggling, seemed very relaxed. Later that night we did the same thing. I left it on an extra ten minutes while he and my other cat played. I removed it again.

-We are at the point now where he just wears it most of the day. I have to say it's amazing. It's like I hit the off button on his anxiety. He was so spazzy that if I walked too quickly towards him when he was lying down, he would bolt away in pure fear until he realized he wasn't about to be murdered. Flight reaction 24/7. I should mention he's all indoor so he's never had a threat to his life to have this kind of fear. NOW seriously I could drive my car through the house and he'd be like "that's neat." (Not that he's apathetic or depressed lol, just that it's taking a lot more of a scary stimulus to make him jolt up or be afraid).

So, random pros and cons at the end here

CONS:
-Sammy kind of gets Hat-Hair when he wears it for a couple hours.
--- Solution: I give him a quick brushing when I take it off and he fixes it himself when I'm done.

-it MIGHT get hot in the summer. He is pure indoor but I live in California and sometimes the heat strikes. I feel like I should note that the material is shockingly breathable. I would compare it to a thick under armor shirt, that kind of sporty material. I really like the material, this is a very high quality vest, BUT it will probably be coming off if temps go above 80F inside.

-Slight risk of it getting stuck on something and slight choking risk because it has the neck strap(Velcro that most cats would be strong enough to kick off if they got adrenaline).
I haven't seen any risk truly but i am aware it is there, so I will simply take it off of him if I am leaving the house.

PROS:
-It worked and WELL.

-Material is high quality, looks like it will last a few years.

-It looks pretty adjustable if you have a fat cat. Sammy is skinny and I bring it pretty tight on him(two fingers still fit under every edge and he does not act uncomfortable).
---side note: Sammy is about 8 pounds but he should be about 10-11 when he gets fattened back up. See pictures for how it fit him.

-Sammy still has FULL mobility. Runs, jumps high, plays, poops, you name it. Took him a few times to learn how to jump up high while wearing it but no big deal.

Final picture is him sleeping next to me literally the entire time I was writing this review(about an hour lol)

Anyways, it worked for me. I will probably update this in a few months when Sammy hopefully fattens back out :) thanks for reading.
PS since it's not that easy to tell if a review on Amazon is real any more(including most of the thundershirt reviews lol) I purchased this vest cash and believe it's worth the 40$. It was NOT given to me free to review, and I do NOT work for thundershirt.