My rogue de Assistant: What sort of animal are we talking

Hi there, you are through to Dr Linda. I do apologise that your question has not been answered more promptly and hope I can still be of some help.
I'm sorry Bruce seems to have injured himself after what sounds like a great and straightforward TPLO recovery.
Certainly, we can assume he had been putting more weight on his front limbs during recovery, to ease the strain. This can make dogs more prone to injuries on the limbs that have not had a surgery. With a history of OCD, we know that Bruce is more prone to the development of local arthritis and other issues.
As the injury was so sudden, he may well have strained himself. You have likely already done this, but it is worth to check all claws, in between toes, pads etc. We are looking for grazes, puncture marks or small foreign bodies. Move each individual joint, fully flexing and extending them, noting any resistance. Feel all along the limb for areas of heat or swelling.
Is he licking at any area on the limb in particular? This can help us localize the discomfort.
Does his lameness improve or get worse after rest?
Is he able to weight bear or is he constantly for touching (hovering the toes above the ground)?
If his lameness improves with rest and he has the ability to weight bear, we would hope that this truly is a strain. With such a large dog, they need Very strict rest (something which you have probably gotten used to recently!) and I would think a daily dose of Metacam is appropriate as long as he has no side effects e.g. stomach upset.
If you can localize the pain, consider using a warm pack on the area for 5 minute sessions three times a day.
He should improve daily and, if not, a vet visit will be in order.
Given his history of orthopaedic issues, it is always important to ensure he is lean and trim and joint supplements should be considered. In a similar vein, physiotherapy and hydrotherapy can be highly beneficial to build up any lost muscle and prevent further injuries.
In this recent cold weather we should prevent his joints from seizing up by keeping him warm and using a padded, orthopaedic bed.
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