Hello, I am reaching out for help/advice in regards to my two dogs, specifically about some sudden aggression.
Apologies in advance for the length of the post, but I want to set the scene / give as much detail as possible.
(1) Franklin. 6 years old. Male. Neutered. Beaglier. 10kg. Have raised him since he was 8 weeks old.
(2) Zorro. 3 years old. Male. Neutered. Bull Arab X. 27kg. We adopted him from a shelter when he was 18 months old.
When we introduced Franklin and Zorro (first on neutral territory, then in Franklin's backyard), they got along famously. Ever since then, they have basically been inseparable. My husband and I work full time, so they are home alone together in the backyard throughout the day. They play together, snuggle together, and have never had an issue. We do separate them for meal time, bones, and sleeping. Franklin sleeps indoors in his armchair in the laundry and Zorro sleeps on the back deck in a kennel.
When we adopted Zorro, he was very shy and timid. He is a very submissive dog. Franklin has always been the dominant dog in the relationship, but he is very gentle, placid and calm (he's also a trained therapy dog). Both dogs are very well socialized with people and other dogs. We take them to an off-leash dog park on a daily basis, out and about with us, on car rides, etc.
On Saturday night, we left both dogs at my parents house for the evening. My mum said Franklin suddenly became very upset and went at Zorro. She didn't see what caused the argument. She separated them very quickly, however Franklin didn't calm down all evening. My first thought was that Zorro had perhaps eaten one of Franklin's poos (Zorro is a bit of a poo-eater!), as Franklin has mildly reacted to that 1-2 times in the past. However, everything was fine the next day, so we didn't think anything of it.
Then yesterday, we were doing our normal before-work routine. I was getting their daily toys, filling the water bowl, etc. Zorro was on one side of the yard (doing absolutely nothing at all), and Franklin trotting around on the other. Then completely out of the blue, Franklin ran at Zorro barking, snarling and nipping at him. This time Zorro fought back; not to his full strength, but enough to tell Franklin he wasn't going to put up with it. I managed to separate them, and took Franklin into the house, where he continued barking furiously. Since I had to go to work, I separated them for the day (left Zorro at home and took Franklin to my parent's house).
I thought the day apart would be enough to calm everything down, but when we reunited the pair in the evening, both dogs were still visibly upset; hackles raised, Franklin barking/growling. Usually both dogs snuggle on the lounge after dinner / before bed. Franklin refused to hop on the lounge with Zorro, was very restless and agitated. When we encouraged him to hop up, he started shaking uncontrollably. Separated them again for the night (like usual), and then this morning, STILL tension. Hackles raised again, Franklin didn't want to go outside to wee as Zorro was out there. Again, have separated them for the day.
In conclusion, I don't know what to do! It seems like nothing has changed / sparked Franklin's aggressive behavior. It's extremely out-of-character and quite worrying, as usually he is such a laid-back hound.
Any helpful suggestions would be very much appreciated. Thank you.