The lump could be many different things, not necessarily cancer. I have forgotten the statistics now, but the percentage of lumps that are cancerous (in both animals and humans) are lower than we think. But it's natural to be concerned, and only a check-over at the vet's can put your mind at rest.
Was the id chip put in recently? There is a possibility there might be a reaction. If the lump came up really quickly, it is possible it might be an abscess (?) Even more likely if it is very sensitive or painful, or looks inflamed. If it's a very soft, round lump, it might be a lipoma, which is benign, but if it grows too big, and affects the nerves or muscle-function, may need to be taken off, (a lipoma is made of fatty tissue) If it is firm, but smooth and very rounded, there is a possiblity it could be a fluid-filled cyst. That could be drained. But don't try and do too much guessing, or second-guessing. Go and get this checked out.
Sounds like it could possibly be a dermoid sinus, it is quite uncommon and more typical with Rhodesian Ridgebacks but also occurs in other breeds.
A couple of months ago my dog had the exact same lump in the same place and we also thought it may be a reaction to the chip. The vet initially put her on antibiotics which knocked out the infection and all was good for almost three months and then the lump reappeared. The vet decided to operate and removed a fibrous mass, she went back on antibiotics for 30 days and 7 days after the final antibiotic dose the lump reappeared. Upon consultation from another vet a dermoid sinus was mentioned. I looked up dermoid sinus on the net and it fit to a tee.. I noticed the hole with hairs coming out of it near the bump during the first visit to the vet and even asked the doc about it but he was not concerned with it.. Not very many vets have ever even seen or heard of a dermoid sinus.
You can diagnose this by pinching the skin between your fingers and rolling it back and forth to check for a sinus, it is difficult to do once there is a bump and it has abscessed but antibiotics should knock it down temporarily. Here is a couple of links to info.
I HAVE A 11 YEAR OLD SCHASHER/SHELTIE MIX I FOUND A SOFT MOVABLE LUMP ABOUT 2INCHES LOND AND 1 INCH WIDE UNDER HIS SKIN ON HIS BREAST BONE. HIS EYES ARE CONSTANTLY RUNNING, THERE IS AN ODER ABOUT HIM ( JUST HAD HIS TEETH CLEANED BY VET) AND HE FELL DOWN OUR FRONT HARD WOOD STEPS BACKWARDS YESTERDAY HITTING HIS HEAD. WHAT COULD THIS LUMP BE. FAT, CYST, TUMOR, OR WORST OF ALL CANCER?
Poor thing. He sounds like he's having a hard time right now. Have you asked the vet about this lump? That would be a good idea. Plus, you need to have the other problems looked at, the running eyes/peculiar smell about him/lack of co-ordination. I don't know what those things are, but if you can get to the bottom of that, his general fitness might improve greatly.
DON'T take my word as gospel! Please do get him seen by the vet, but a soft, movable lump does not necessarily suggest a cancer to me. I have a very lumpy dog, she has some lipomas (fatty tissue) which are soft and movable, and gets cysts (fluid-filled smallish ones) now and again, which come and go. EVERY single new lump gets checked out professionally, but I am becoming a lump-connoisseur (is that how you spell it?) with my dog, and have got used to how all these different lumps feel.
My 13 y.o doberman, has a growing lump on his neck, his liver enzymes were elevated. Could this be a lipomsw, or lymphoma?
My 3yr ols am. Bull dog / pit has allergies his last reaction was pretty bad he has a small hard bump on his neck where he always reacts. With benadryl his skin is getting better the bump seems to have dried up some to me. I looked up on a pet MD we site about it and it said it was associated with allergies. Had anyone ever seen this. Well it go away with allergy medication or with he need something stronger?