My cat is losing fur on his back and flinching when petted.

I recommend taking him to a veterinarian. If he is not on flea prevention I highly recommend using it as you may not always see fleas on cats. It looks like he has a skin infection and needs antibiotics so taking him to a vet is important. Thank you for using Petco Pet Education Center, formerly Petcoach

It looks like she may have a skin infection. Hard to know what exactly started it. Could something hot have dripped on her? She may need some antibiotics. I would encourage you to have her evaluated by a veterinarian. I hope she improves quickly!

This may due to an extremely severe allergy, a burn injury (so the skin which has fallen off died) but it could also be infection (bacterial or viral) or mites. An immediate check up is absolutely needed as antibiotic treatment and pain relief medications will be needed. Hope this answer was helpful, but please do not hesitate to contact us again on the forum or by requesting a consultation if you have any more questions or to discuss it any further.

Poor kitty. This looks like a really bad skin infection and could be due to an underlying flea allergy. Luckily veterinary hospitals are considered an essential business, so most are open even with the lockdown keeping other things closed. Your cat needs to see a vet to get this taken care of and also figure out what is causing him to limp? He will need at the very least antibiotics to help clear up this skin infection. I do hope that you are can find an open vet close to you soon. Best of luck and take care.

Based on the picture it appears that she may have had a lot of clumping debris on her fur? If her skin was irritated from debris encrusting the underside of her belly then it could cause enough irritation to cause hair loss. Also skin infection and ringworm are also possible causes. I would encourage you to monitor her closely for any other changes. If You feel the shelter vet if too busy then I would encourage you to consider having a second opinion. Best of luck and I hope she improves soon. Thank you for using Pet Coach.

Thanks for using Petco Pet Education Center, formerly Petcoach! This could be due to a number of reasons such as allergies, a bacterial infection, mange, among many other reasons. It does sound like you think he may be feeling sick as well so I highly recommend that you have him evaluated by a veterinarian for further assessment and treatment so that he can be started on the right therapy. Best of luck!

That is definitely an interesting pattern of hair loss. I suspect this has to do with some sort of trauma. A scrape if he was trying to get “through” something, a chemical or thermal burn down the back, even a reaction to a topical medication such as a flea and tick application. From the picture the skin appears pretty normal, but pictures can be deceiving. If the fur does not appear to be growing back soon, or if it looks to be spreading then I would encourage you to have him evaluated by your veterinarian as soon as possible. Best of luck and thank you for using Pet Coach.