1.5 yr old male starting to show aggression to other animals
Hey all, this is my first post on here and sadly it is one asking for help/advice. I have a male GSD named Apollo who is 1.5 yrs old. I got him straight from a breeder who went over the pedigree with me for about an hour and I was able to meet the pups parents. He comes from working dog lines, with brothers from other litters serving as K9 and federal work dogs. We got him when he was 8 weeks old. Up until about three-four weeks ago I have had no issues with him. Now he has started showing aggressive tendencies to the other animals that are in the house. We have a five year old lab and two 3 year old cats (my wife's not mine). Every time an animal comes close to him, he growls at them. This has now progressed to him standing up and starting to approach the animal that is coming to them. This only occurs when it is towards the end of our day and are sitting at a table, the computer desk, or on the couch. When he does this, I firmly say no and step between him and whichever animal he is growling at and approaching. It has not escalated into snapping or fighting, but I am afraid that it will get to that point. I can let him and the lab outside and they will run and play all day long as if nothing is wrong but it is completely different when we are inside. I have called multiple trainers in the area and the ones that I actually got through to have said that they can not help me due to the fact that it happens in home and not when we are out and about.
Also, I have noticed that he absolutely has to be at my side every time I am in the house. I think it might be a form of possessive aggression. He growls both at my side and when I make him lay down in another room. If he is in another room, as soon as he is told no and made to lay down he tries to get up and come right to my feet. There has been absolutely no sign of aggression towards other people and I have been told many times that I have an amazing dog both from his looks and how he treats new people that he is just meeting. If it helps, he has not been neutered yet, because the breeder and vet told me to wait until he was 2 yrs old to have it done. However, after the recent attitude change, I have made an appointment for the 22 of this month to have him neutered. And he has grown up with the other animals in the house. We have had our lab since she was 9 weeks old and we rescued the cats from a shelter when they were tiny kittens.
I live in Illinois in the Quad City Area. If anyone has an advice on a reputable trainer or behaviorist that is either in the QCA or even Chicagoland area, that would be much appreciated. I do not want to send him away to someone to have him trained, if possible, because I want to know if I am doing something unknowingly to encourage bad behavior and I want to do everything I can to get him to stop being aggressive to the other animals. It is almost to the point that my lab and the cats give him a wide berth when they are walking around the house while he is laying down.
Thanks in advance to anyone who reads