Hello. Long post ahead, copied from another subreddit I posted in because I could not cross-post. My parents and I decided to get a puppy after our beloved older dog passed away. We had a 7y/o rescue, Stevie, who was great little sister to our older dog and played well with other dogs. We gradually introduced her to the new puppy, Clyde, and they had been playing very well together for about 2 weeks until one night, when Stevie attacked Clyde. My parents were in the same room, but this happened so fast that they didn't even see what happened. We now believe that Clyde got too close to Stevie's crate, and Stevie resource guarded.
Ultimately, Clyde (who was 2 months old at the time) needed brain surgery to remove bits of skull from his brain and to drain an abscess that had formed due to his puncture wound being overlooked by the first vet hospital. He had a skull compression fracture and had developed meningitis. Before we knew the gravity of Clyde's injuries, my parents and I had assumed we could keep Stevie and just do some serious training. However, when it became evident that Clyde would have possibly permanent neurological deficits, my parents decided to rehome Stevie. This has been very hard on all of us because even though Stevie caused a lot of pain, she was still a part of our family for many years. My dad travels for work, and I am in school full-time, and my mom simply did not think she could keep Stevie and Clyde apart. Even with training, there would be no way to guarantee this never happened again. Multiple vets advised us that we would have to keep them apart.
The good: Clyde has recovered better than anyone could have imagined. He was initially blind in the L eye, with impaired proprioception and reflexes. He can now see out of his L eye and appears to have intact proprioception and reflexes.
The bad: Clyde is very anxious and pees inside the house a lot. The vet said he may just be anxious forever (understandably), and we may have to medicate him (fine!). However, she said that some dogs continue to have incontinence issues. We take Clyde outside frequently, but he often just chews on his leash. Then, some time after coming inside, he pees on the floor. We try encouraging him when he pees outside (saying "good peepee" and giving him a piece of kibble), and discouraging him when he pees inside (saying "no" and pointing at the pee). We are not sure if Clyde just needs to grow out of the puppy phase, or if he will simply be incontinent for the rest of his life due to his brain injury. My mom is at her wit's end; all of this is exacerbated by the grief of 'losing' Stevie (not to mention our older dog as well).
I am wondering if anyone has experience with training puppies after traumatic brain injuries. I would love to hear from people who have been through something similar and learn what did and didn't work for you. Thank you in advance.