I noticed it this morning when he came inside after his potty break and so I figured he stepped on something. I didn't notice anything in his paw pads so figured he may have just twisted/sprained/stepped wrong.
10 hours later and he's still limping. He holds his paw up and won't put any weight on it. I give him a tablet of Deramaxx (an pain med for dogs) to see if that helps. I'm a bit concerned giving him this medication because our dog Rose died because of a reaction to it (it ulcerated her bowel, and she died of internal bleeding). While I know that Rose's case was very unusual, and at recommended doses Deramaxx is a good drug, please believe me that I'm still a bit spooked by Rose's experience and I only gave it to him because Seamus was in pain.
However, an hour later, and the drug seems to have had no effect. He's still limping and won't put weight on his paw.
In my experience (what I call the "Year of the Three Rottweilers"*), an older dog that suddenly starts limping and the pain doesn't respond to a non-opiate pain med has meant only one thing. A really bad thing. Seamus isn't all that old (he's about 7 or 8) but old enough to fall into the "increased risk of osteosarcoma" category. Osteosarcoma is not really treatable. From what I understand, by the time it becomes obvious (a limp), the tumor is growing enough to have started to break the bone (which is what causes the pain). Also, it's likely to have metastasized by that time.
I will wait and see if his limp goes away. If it seems worse, I will take him to the vet and brace myself.
*The Year of the Three Rottweilers:
Rottweiler #1: Haida
When we found out that Haida was suffering the disease in her foreleg, our only options were euthanasia or amputation. We elected amputation, even though her chances of surviving more than a few months were only 50-50. (This should give you a good idea of how much we loved that dog to elect a procedure in which her prognosis was essentially a toss of the coin.) She did survive the operation, and was recovering quite nicely but the disease had spread to her brain and three weeks after her operation, she suffered a string of seizures and died.
Rottweiler #2: Carla
We adopted her a few months after Haida's death. In my grief, I was looking at Petfinder and came across her at the Humane Society in Kelso, WA. She had been in the shelter for a long time and had terrible calluses on her elbows and knees from sleeping on concrete. She was a total sweetheart. She turned out to be deaf, which wasn't a problem for us, but she also had a slight limp, which turned out to be a really big problem. In a single day, that slight limp turned into an inability to move without crying out in pain, so we took her to the vet and found she had a tumor in one of the vertebrae in her lower back. Amputation was not an option, so three weeks after we'd adopted her, we had her euthanized. It bothered me so much that her calluses hadn't healed; obviously, her time was limited anyway, and I'm still glad she spent her last three weeks with us instead of in that filthy kennel, but her calluses were healing nicely. The hair was starting to grow back, as the vet noted while she was injected that bright pink solution of death. I was very startled by her comment, and wanted to yell "What the frack are you talking about her calluses healing right now? You are euthanizing my dog!"
We got Rose a few months after Carla died when my friend who runs a pet shop in Seattle told me about a woman who came in with her two foster Rotties, and after interacting with the dogs, he thought Rose would be a perfect dog for us. It turned out, he was right. She was the third in a row of fantastically tempered and wonderful Rottweilers. After taking Rose in for shots, the vet staff asked us where we found such consistently wonderful dogs. (Every single one was rescued from a shelter. Rose came to the private rescue group from Spokane Animal Shelter.) But Rose did suffer from joint pain, which is not unusual for larger dogs which is why she went on the Deramaxx. And although she never exceeded the recommended dose, she reacted to it and died very suddenly a few months after we got her. (I made the vet perform a necropsy, which was admittedly very difficult for him but this is how we found out how she died.)