My kitten pants when slightly hot outside. Is this a vet concern?

You're right that it can be normal to see short periods of panting after active play or other exercise, especially in young cats. But, this can also be a sign of heart disease or other problems. If your kitten sometimes pants, it would be best to have him examined be a vet to make sure that his heart and lungs are normal. If no problems are found, then you'll know there is no need to worry :)

Your kitten will need to have an exam by your veterinarian. She could be suffering from a congenital malformation of the blood vessels near the heart or have a hole in the septum of the heart. This would often not show when the kitten is resting, but when it exercises, runs and plays there is not enough oxygen being pumped to the lungs and muscles because oxygenated and used up blood mixes. Problems often do not occur until 3-4 months of age. Please make an appointment with your vet for an exam.

rapid breathing is not uncommon in kittens but if he is breathing fast with an open mouth it is definitely not normal, at this age it is usually caused by aspiration pneumonia (milk aspiration to the lungs). in such a case you would need to take them to the vet in order to get it checked and treated ASAP.

You can try keeping them indoors with a fan or increasing the shade they have. Sometimes doing slightly cool water by placing a few ice cubes in their dish is helpful as well. If they start having any sort of nasal discharge, become week are they have pale or discolored gums they need to be seen by veterinarian immediately.

Poor Kane! Given that he has calmed down, I am thinking that that panting was from stress; nevertheless, keep an eye on him just in case. If you see him start panting again, drooling, agitation (may be shown by pacing), a bright red tongue, or breathing distress, take him into a vet immediately. I hope this helps!

If he was really racing around after the toy last night, more than usual, it could explain his exertion, however, it wouldn't be a bad idea to get him in to see your vet for an exam just to be safe. You said Obi is a big cat, so there may be some Maine Coon in his background, and they have a greater risk for some heart conditions.

How lovely of you to take in feral cats! Yes, it certainly is possible Butternut could have a bad heart, but the only way to know for sure is to have him seen by a vet. It would be a good idea to have this checked out, as medications may help with any symptoms he is displaying. I would urge you to have him seen by a vet for at least a physical exam and chest x-rays. I hope this helps!