My dog has started snapping

Most weekdays I visit my mum taking Robs my Yorkshire Terrier with me. She has a springer spaniel who is about 13 now and Robbie has started having a massive go at him, snapping and getting quite nasty with him. He has done it a couple of times but its just come out of the blue. Ged, the spaniel doesnt seem to do anything to provoke it, doesn't retaliate in any way and we have been visiting for over a year so there doesnt seem to be any reason for it? Any ideas?

She`s probably doing it because she can. The dog`s too old to do much about it so it`s up to you to stop it. I`d keep her on lead around the old dog, or use safety gates.

Thank you for the advice

I'd get the old dogs health checked. It could be yours is picking up on him having a medical problem. Dogs used to pick on my half blind one and several had a go at my other dog after he got sick but wouldn't have dreamed of doing so before.