Bumps like this can be a form of cancer on your dog, here's a quick guide to the different types of externally visible tumours you might come across:
- blackish (melanomas),
- purplish (hemangiosarcomas),
- fleshy, inflamed and red (histiocytomas), l
- ook like a non-healing open sore (squamous cell carcinomas),
- be firm, hard and deeply attached (fibrosarcomas),
- or have any appearance (mast cell tumor, the great imitator).
However there is absolutely no way of telling without a closer examination and biopsy, so my advice would be to absolutely take your dog to the vet.
This is especially true when you notice any physical change in your dog coupled with a behavioural shift or abnormal tendencies.