Lump on doggo

Hello, just today I noticed that my lab has a big lump on his left hind leg. Doesn’t seem to cause him pain when I touched it. Any help as to what it could be would be very appreciated 

Hello! - as with all lumps, the main thing is that this is very difficult to diagnose by looking, or even by palpation.  We all tend to be tempted to have a feel during the clinical examination, but the majority of the time vets will reccommend either biopsy or complete removal before giving a definite answer as to whether a bump is sinister or benign.  Rarely, a lump could turn out not to be a lump at all but a hernia or an oddly descended testicle.  This is where palpation (feeling) can help to differentiate.  Therefore your vet may well ask to palpate the lump, then do tests (ultrasoud and / or sampling depending on their suspicions) before coming up with a best-guess and reccommended plan for each lump.