Permabanned
So basically if you ring the RSPCA and they ask if he lets them out for exercise you have to reply you have no idea, but you hear him swearing at them? Can't see that getting very far, have you expressed your concerns to him directly as an initial move? Are they kept clean, fed and watered? Having nine or more dogs I have literally not been away on holiday for over 20 years, but that's my problem, such a large number precludes boarding kennelling them and I am happy to forego holidays in order to enjoy the pleasure of keeping them correctly. They come out two at a time to the (infamous) pubs three times a week and get virtually free run of 17 acres of well fenced fields and woodland three times a day. Some live in the house at night, the others have purpose built heated kennels outside. Others have different priorities when it comes to keeping animals I'm afraid. If you are genuinely concerned there are various paths to go down, but possibly / probably at the risk of inter neighbourly disputes. 3.15PM, time for another walk....
