At what age does dog aggression usually start to come to the surface? Are keeshonds a breed that is prone to same-sex aggression? I ask because I am dogsitting for a pair of male Keeshonds, with one that has started to display random aggressive behavior towards the other, older dog. Granted, the older dog has epilepsy and occasional seizures, which may be contributing to the problem. However, since I don't know a whole lot about dog aggression in general, I was curious to know more. For the record, I have already called the owners about the issues and left a message, her phone turned off since they only left this mornign and are probably still on an airplane somewhere. In the meantime, I am keeping the two dogs completely separated while I'm dogsitting, just so I don't have to worry about further attacks. Still, it's information that I should be more familiar with. Thanks! Oh, and please feel free to grill me on this one. This is stuff I need to know if I am going to be serious about dog-sitting, and I'm sure there are factors at work that I don't even know to look for. I'll answer questions as best as I can, but my internet will be limited to my phone this evening, and I may not know all the answers about the dogs specifically since they aren't mine. Thanks again!