small lump at injection site

We are at the in-laws for the memorial day weekend, but I was rubbing down Oscar and noticed a firmer than usual bit of tissue about the size of a marble where I usually give him his insulin injection. We inject on his side just behind his left arm-pit. It isn't rock hard or anything, but it is firmer than it should be. There is no matching bit of tissue on the right side. I do alternate the sides some, but I use the left side more often. I try not to get the exact same area each time, but it looks like it was close enough together each time to effect something.

Is this normal? Benign? Something to take him to the vet over as soon as we get back?

 

You do need to alternate injection sites or the skin gets scarred and can go hard. I did left, middle,right of the scruff.

Try doing it in a square.

Would keep an eye on it, if worried then a vet trip to put your mind at rest.

 

Not an emergency but definitely have the vet look at it when you get home.

Two of my cats have had lumps -- one was malignant and one was a benign fatty tumor. Neither was at an injection site - Both were removed (not at the same time).

 

Thanks for the replies so far. My mother-in-law is diabetic and uses levimir. She told me she noticed a similar lump on her thigh where she shoots and her doctor told her its her tissue's reaction to the insulin being so cold while being injected :?:

 

Interesting about the insulin being cold! We injected Left in morning, and Right at night after I began to feel little lumpies happening. I like the Square shooting idea.