My dog's thigh has a red, changing lump. What should I do?

Hello, this looks like a histiocytoma, a benign tumor. Fairly common in younger dogs, it usually spontaneously regresses without treatment. Have your veterinarian take a look to make sure that it is not anything else. Thank you for using Petco Pet Education Center, formerly Petcoach.

I'm not sure from the picture if it's just the mass the side a little bigger than your thumb nail, or if the entire 6 inch round area around the main bump is red. Either way, I would be worried about a growth first and then perhaps an insect bite if you've only noticed it today. Young dogs can have a type of mass called a histiocytoma that is benign and goes away on it's own eventually. I would recommend a vet visit if it's growing in size, just to be on the safe side.

I would recommend to take Atlas in to get that mass aspirated. Any red mass should always be checked as there is the concern for a malignant tumor called a Mast Cell Tumor. The aspiration will most likely be able to tell what kind of mass it is and if it needs to be removed. Do this sooner rather than later! Please post again if you have any further questions!

The photos are a bit grainy but I think what I am seeing is a lump that looks like a histiocytoma. It usually will go away on it's own within a few weeks to months. I suggest you leave it alone. If it bothers him or doesn't go away then you should have your vet take a look at it. ( https://veterinarypartner.vin.com/default.aspx?pid=19239&id=4952066 )

There are a few possibilities as to what this could be on Ruby. In a younger dog benign masses called histocytomas are possible. These generally regress with time. However, masses like mast cell tumors can also present this way. Mast cell tumors can be problematic and need to be surgically removed. Mast cell tumors also release histamine so please do not continue to try to squeeze this growth. Some other causes of this (although probably less likely) are cysts or infections. I recommend taking Ruby to see your veterinarian so that a sample of cells from the mass can be obtained. This will help in diagnosing the growth and in deciding if it needs to be removed surgically. Thank you for using Petco Pet Education Center, formerly Petcoach and I hope this turns out to be a benign issue for Ruby.

Hello, younger dogs get benign red tumors like that known as hemangiomas. Older dogs may still get them, however, the malignant version hemangiosarcomas would also be very possible. Its likely that to determine wether benign or malignant, the mass will have to be removed and submitted for biopsy. Once results are obtained, then your veterinarian will be able to guide you with the next appropriate step. Hops this helps and best of luck.

Unfortunately there is no way to tell what that is just by looking at it. It could be a benign or malignant growth. I am concerned that it could be a mast cell tumor and I recommend having Lexi examined by her veterinarian. They will take a sample with a needle and examine it under the microscope to determine what it is and what treatment is needed.