Hello I am Dr. Joey. Thanks for trusting me to help you and your pet today. I am a licensed veterinarian with over 16 years of experience. I look forward to working with you.
I am pleased to hear this is not painful for her. There are many possible causes for this. Yes, this absolutely could be bursitis, although that usually IS painful in most dogs. The question is if this swelling is originating from the joint, itself, or coming from a subcutaneous mass. This is a very important distinction and not one I think could easily be made at home. Masses that change frequently in size are concerning, especially for something called a mast cell tumor. Alternatively, I have had dogs with moderate arthritis also have this type of variable swelling.
The safest route is for you to have your veterinarian examine Riley and then two test would be most useful to provide an answer for what this may be. First, is a needle aspiration of the swelling/mass which can then be submitted to a pathologist at the lab for evaluation (that will tell us if this is joint fluid versus if this is a mass/tumor). Second is to take a radiograph (X-ray) to confirm there is not actual bony involvement. If there is bone involvement then we need to know if this could be a bone based tumor or infection Both are usually painful, which makes either less likely. We do sometimes see non painful swellings from joints such as you have described which are not concerning. But some of the other items I have listed are very worrisome and require therapy as soon as possible.
Glucosamine? Sure. But not all supplements are created equal. I recommend one of these dog supplements as I trust these will have in them what is claimed on the label: Tri-cox, Dasuquin, Cosequin, Glyoflex.
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