Strange muscle swelling?

This is my dalmatian mutt, Eve, and she's just over 10 years old. She has bad arthritis, and had surgery for a torn ACL a year ago (this is that same leg). I'm not sure what this strange muscle swelling is and am wondering if anyone has seen something similar? She is also covered in lipomas, but all her other lipomas are round and squishy, this is not.   Species: dog Age: 10 yrs Spay/Neuter status: spayed Breed: dalmatian mutt Body weight: ~65 lbs History: spayed, swallowed a needle (surgery), bladder stones, tail amputated b/c of a tumor, torn ACL, lipomas Clinical signs: hard swelling Duration: about a month General location: North Texas Test results/x-rays/vet reports: none

Hello!  I'm worried about this as I'm afraid that there may a tumour / cancer, eg of muscle, tendon, connective tissue or bone.  There might be other possibilities eg an enormous lipoma or dramatic overgrowth of muscle tissue / tendon sheath eg in compensation for an injury, or fluid filling such as an abscess (often accompanied by extreme lethargy), but if this were my dog then I would definitely want it checked out.  This may involve a biopsy, or some other method that the vet who can feel the area feels is appropriate.  Wishing you both the best of luck and please do come back and let us know what you find out.

If your dog experiences a sudden, unexplained swelling on any muscle, it is important to take him or her to the veterinarian as soon as possible. While this symptom may not always be indicative of a serious health problem, it is always best to rule out any potential issues. Some of the most common causes of muscle swelling in dogs include injury, infection, and inflammation. If your pet has recently been injured, experienced a fever, or shown other signs of illness, the swollen muscle could be due to one of these conditions. In order to determine the root cause of the swelling and provide appropriate treatment, your veterinarian will likely need to perform some diagnostic tests.

You might want to get her checked by your vet immediately. Maybe something went wrong with her previous surgery or she might have torn her ACL again. It really is best to consult with your vet to know the exact cause of this muscle swelling. I hope she is well now.

You can learn a lot about ACL on https://tploinfo.com/ . When my dog was scheduled for a surgery, I found a lot of information about the surgery and it really is quite helpful since they have guides for pre-op and post-op.