Recently I had to take my cat to the vet because he stayed out overnight and when he came back I could tell something was very wrong. He wasn’t able to walk straight and barely able to stand up. I noticed that he could put pressure on one of his back legs but could still barely stand on it when I let him out the day before he was completely fine and usually he loves to play and if you try to scratch his belly he’s going to be clawing at you. When I brought him inside he immediately just laid down and allowed me to rub all over him with no response. He wasn’t shaking and didn’t seem out of breath. I took him to the vet and they told me the flea collar was the problem but I was surprised it could get that bad in the 12hours he was gone and he’s had the collar on for weeks. This happened yesterday and today he’s about 80% better just slightly off balance. I would really love some input from someone who has had side effects from the collars before I am more concerned that this may have been something that he had eaten or was bitten by since it happened so quickly.