Red lump

My dog is a multipoo, he is 9 years old, eating well, has a red lump on back feels hard doesn’t seem to hurt him or to annoy him at all. I am going to ring vet and get it checked out but do you think it is harmless. He is fine in himself but lump is hard and red. He has very curly hair and you can see it through his fur 

Hello!  This one could go either way, I'm afraid.  Many apparently painless lumps on the backs of animals are nothing to be concerned about;  cysts, old bites, benign tumours or follicles that have become inflamed, such as a reaction around a Demodex mite.  However, skin cancers can also answer this description - and not infrequently, even the vet checking the lump in person may not be able to tell, so they may try conservative treatments and monitor the lesion, or order sampling for histology.