I agree with Dave. You may want to have Otis checked for Lyme disease. Its actually not so far fetched to think it may be Lyme disease. Our mastiff Molly started having problems with limping and lameness in her front shoulder. Fortunately, our vet suggested we treat her for Lyme disease when the x-rays showed nothing because she tested Lyme positive.
Most all dogs in our area end up testing positive for Lyme at one point in their lives because Lyme is prevalent in this area. Just because they test positive does not mean they have the disease though (our old girl Emma (RIP) was Lyme positive for 12 years never showing any clinical signs of the disease), but if they start showing symptoms, treatment with antibiotics is the rule out this way. Molly was two years old when she started showing clinical signs and it came on fast. She woke up lame one day and went down hill from there with her limping getting worse with each passing week. She started sleeping a lot more too. Not wanted to play like she used to. Once treatment was started, she began feeling better and stopped limping after only three days on the Doxycycline, but we kept her on it for four weeks. She has had a complete recovery because she was treated in the early stages.
Please don't rule out Lyme, especially if the x-rays are not showing anything. If not treated early Lyme disease can lead to long term joint destruction/arthritis. Keeping my fingers crossed that you get a diagnosis on what is ailing Otis and that he have a complete and speedy recovery.
Most all dogs in our area end up testing positive for Lyme at one point in their lives because Lyme is prevalent in this area. Just because they test positive does not mean they have the disease though (our old girl Emma (RIP) was Lyme positive for 12 years never showing any clinical signs of the disease), but if they start showing symptoms, treatment with antibiotics is the rule out this way. Molly was two years old when she started showing clinical signs and it came on fast. She woke up lame one day and went down hill from there with her limping getting worse with each passing week. She started sleeping a lot more too. Not wanted to play like she used to. Once treatment was started, she began feeling better and stopped limping after only three days on the Doxycycline, but we kept her on it for four weeks. She has had a complete recovery because she was treated in the early stages.
Please don't rule out Lyme, especially if the x-rays are not showing anything. If not treated early Lyme disease can lead to long term joint destruction/arthritis. Keeping my fingers crossed that you get a diagnosis on what is ailing Otis and that he have a complete and speedy recovery.