[quote=esprinter]As long as your Jack Russel does not have small dog syndrome, there are plenty of "Molossers" that would no doubt love to play with him... Not all of them are tough guys. Far from it. English Mastiffs, Bullmastiffs, St Bernards, Great Danes, Irish Wolfhounds, and Newfoundlands are all Molossers and they are mostly gentle giants. In fact, I have seen the Newfoundland referred to as the worlds most gentle breed of dog.[/quote] I don't think she has SDS, although she can be quite a pushy little broad. She has the "give her an inch" syndrome, for sure, and, while she isn't aggressive toward big dogs, she has no fear of them (or anything else for that matter, which can be dangerous). Her main objective with other dogs is to get them to run from her so she can chase them. She is aggressive sometimes with small dogs, but that's not an issue for this discussion (she once "shark-shook" a Chihuahua at a dog park, like it was a rag doll so no more dog park - I would be devastated if she killed or seriously injured somebody else's beloved pet). I have always liked Irish Wolfhounds - they seem just glorious to me, but I understand that guarding is not their strong suit, although its size would give any would-be robber pause. I like Newfoundlands, too, and know what loyal, gentle family dogs they are while being hard workers and good guard dogs. Their sort of doofus look is part of their appeal. That could be a good choice. Are they any good at hunting - do they have any interest in that or at least enough hunting instinct that they can be field trained? Of the breeds you named, which do you think would be a good guard dog with some hunting ability that is calm and gentle enough to not get irritated by a bouncing Jack Russell? Since the Jack joined our pack (family) first, she's going to want newcomers to be lower down the totem pole than she is. We would probably have the guard dog sleeping outside at night in warmer weather, inside with a doggy door in winter. The jack sleeps with us under the covers and there is no way she would ever give up her position as top dog, and that could become a deadly problem with the wrong molosser because of their size and jaw capacity. My husband doesn't like Great Danes for some reason but the two I discussed above or the EM I think he would consider and grow to love. I'm the one more interested in getting a guard dog than he is when the time comes, but if it could hunt fairly well he'd be fine with it, too. As Platz said, he could take them both hunting (the molosser and the JRT). Will a Newfoundland retrieve? With field training, maybe? I guess what I would want is a dog who will play nicely with or at least calmly tolerate one or more JRTs, tolerate/ignore some outdoor barn cats, show an interest and ability to hunt game or retrieve fowl, lay by the fire and have a good snore during an afternoon nap, rip the throat out of an intruder in about 10 seconds and be intelligent enough to know the good guys from the bad guys.