Sudden Aggression

I have a 9 year old lab/pit mix, a 4 year old lab/corgi mix and a 13 year old schnoodle who all live in my home. They have been together their whole lives. Suddenly my lab/corgi is been slightly aggressive towards my schnoodle. He growls at him every time he walks by him. They have always gotten along before. Any ideas what may be going on?

I would get your schnoodle checked by the vet in case of any health problems. Sometimes dogs pick up on problems from another dog.

As a matter of fact our Schnoodle is in renal failure and was very sick but doing much better now.

Ah well that probably explains it. Maybe you are thinking it is a growl, which it might be, but not a bad growl. It maybe a greeting from him to the other dog. If there is no malice eg: biting etc. then I would think on the lines of him saying something in dog language to the other dog. If you understand what I mean. Pleased to hear he is better now.

The showing of teeth is a sign to say beware you are being warned to keep your distance...As been said before if he isn't biting then I wouldn't worry too much...

Something that sounds silly but might be an answer. Have you bathed your dog since the vet visit? Whenever one of our cats or dogs has gone to the vet, when they come home the other animals act weird around them until the vet smell is gone. I don't know if that be a possibility.