If you have a male dog and your bringing another male dog dont introduce them on your yard. Your first male will try to defend his territory and could end up getting in a fight with the other one. Introduce them somewhere else so they are not on either ones territory, if you do this it is less likely they will be aggressive toward each other. If you are bringing a little puppy than your other male dog wont see the puppy as a threat. It worked with my dogs.
If you are having the dogs work together or live in the same house, they need to be introduced.
there might be something wrong with your other dog. Dogs can sense things we cannot.
were dogs use the bathroom
From eating bad food and dead animals. there might be other reasons that i don't know though.
W.C. Fields
Actually most dogs do NOT do this; a dog that does this might have a dietary issue, an emotional issue, or be suffering from pica. A vet exam is in order, first, and then some behavioral analysis and training suggestions for how to eliminate the problem.
Providing the French Mastiff is used to being around small dogs then it should be fine. Always introduce dogs to each other on neutral ground to reduce the possibility of a fight. Never attempt to introduce dogs if you think it might cause trouble.
If you introduce them when they are both small they might. Other than that the dog (if older) may think it is a running toy and try to chew on it.
if you introduce him with other dogs from a young age, then yes
You might contact a licensed/registered breeder in your area and ask his advice.
try going to a dog park or taking him on a walk. you should see other dogs then.
That would depend on whether your 4 year old is socialised with other dogs and used to other dogs, and also how you introduce them and make them used to each other. It is best to introduce them on neutral grounds and then see how they react to each other.
Providing both dogs are used to other dogs being around them, yes. However, NEVER introduce the two dogs insde a house - introduce them somewhere that is neither of them's territory (a park etc.) before putting them in the same house together. Remember that an entire male and female will almost certainly breed so you might want to consider spaying/neutering if you don't want to breed.
well some times they are not very good with each other but introduce slowly and let them mix!!
It all depends on the dog. Example: Shih-Tzus love other dogs while pugs might hate other dogs.
there might be something wrong with your other dog. Dogs can sense things we cannot.
never introduce dogs to a hampster
They might be mating.