A 13 yr old w/ arthritis who always holds his head down and trips/slips makes me think that he is indeed showing signs of pain. If he wasn't in pain, he wouldn't be holding his head funny. Remember too that dogs mask a *lot* of pain...
If it were me, I'd be wanting to give something daily to manage both inflammation and pain for this little senior kiddo. He probably needs it and will need it for the rest of his life. I'd get him into the vet soon
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