Liz Buchanan BVSc MRCVS
Hello! Fat is laid down a little differently in all individuals but in some, it appears to be laid down in encapsulated lumps called lipomas. I'm not sure that the reason for this is well understood but it is true that in a lot of cases, weight loss can help considerably.
Of course, this only works for true lipomas; there are various lumps that may look and feel like lipomas but turn out to be cancerous. Testing may well be important here, but the most reliable tests are biopsies which can be expensive. The position of the lump can prove important because sometimes, even a lipoma can cause problems eg under the armpit, altering gait. Appropriate dental care is also important; it can have a huge effect on an animal's welfare.
Testing lumps is one way of dealing with this problem, but it is important to talk to your vet about how accurate / reliable that result would be.
In your situation, it may well help to ask the vet what they would do, given what they know, and X budget to use to the best effect.
Please do let us know what you decide.