Last week I talked to the vet, and she had some answers about what happened to Rolo.
The preliminary investigation didn't indicate any obvious signs of death. There was nothing wrong with his internal organs or any signs of trauma, so they had to dig deeper and do a toxicology report and bacteria cultures.
Toxic Shock Syndrome (TSS). (This is a good article that explains the disease if you're interested.) They have no idea where he got the strep infection or why his body reacted the way it did, but that's what led to his death.
This type of reaction is extremely rare. It had nothing to do with his breeding, and it can't be transferred to my boys or the other pets. It was a freak occurrence. There was no way it could have been prevented, and no way to treat it. Even if they had known it was TSS when I brought him to the vet, they couldn't have saved him. Antibiotics wouldn't have helped. All they could have done was make him comfortable, and that's exactly what they did.
Even though this information won't bring him back or unbreak my heart, I'm glad to have it. I don't have to worry and wonder anymore. One of my biggest fears was that someone had poisoned Rolo and that substance was still in my yard, accessible to my kids and anyone else who visited. Thankfully, that wasn't the case.
I still miss him every day, but at least my questions have been answered.
I'm thankful for what the vet did for him, and for what the vet lab found out. I'm thankful for my family, friends, coworkers, and strangers that supported me in finding answers and continue to support me through a difficult time. I'm thankful that I can bring another dog into the house and not have to worry something bad will happen to it (although I'm sure I still will).
Most of all, I'm thankful for the short amount of time that Rolo was part of our lives. He made us so happy, and I spoiled him rotten. It still amazes me that a small furball could mean so much and make such an impact, but I'm grateful he did.