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I would like to help you and your cat with this question, but need a bit more information in order to better assist you.
Both legs feel the same temperature. The paws both look exactly the same.
Sammy does go outside all the time, using a cat flap - he managed to get through the cat flap this morning but is not using the poor leg at all.
I have felt all up his leg again and the only place that I got a little "meow" from him was at the very top of the leg, The only way I could describe this area is like "the armpit" on a human. It is the front right leg and from checking out the paw there is nothing wrong with this or the nails, he just cannot bear any weight on that leg.
I also want to mention that there are NO human pain killers or fever reducers that you would have at home that are safe to give a cat. Aspirin, acetaminophen (paracetamol) and ibuprofen are all very toxic to cats and should never be given! You can read more about them here:
Given that this has been a couple of days now, I would strongly recommend that you take Sammy in to see his family veterinarian to have him examined. He may need to have the leg splinted for a few weeks in order for it to mend.
I hope that this helps you to help this kitty!
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The above is given for information only. Although I am a licensed veterinarian, I cannot legally prescribe medicines or diagnose your pet's condition without performing a physical exam. If you have concerns about your pet I would strongly advise contacting your regular veterinarian.