My apologies for my delay in reply. As I am sure you can appreciate, my own patients keep me quite busy during the week.
Now collapse in older dogs is something we can see for a few different reasons. From what you have described in your reply, I'd be less worried about seizures and brain lesions but would be concerned about possible heart issues or that we have a severe/intermittent spinal or nerve issue. As well, I cannot exclude underlying arthritis playing a role but it sounds like it may be a side issue if present as opposed to the primary problem. And I would just note since his urine is concentrated, the dribbling is likely a side effect and not pathological itself.
With this all in mind, if he were my patient, I'd want an exam (not an emergency) to assess his heart alongside a neurological check to determine if there is any spinal or nerve involvement. At the same time, his joints cold be checked as well. That way we can pinpoint the root cause and that will allow us to target treatment to reduce these episodes for him. Any delay and we could at least try to reduce any arthritis component with OTC joint supports (ie glucosamine, chondroitin, omega 3 fish oils, Duralactin). And I'd note the omega 3's are natural anti-inflammatories which may also help with mild inflammation in the nerves/spine.
Overall intermittent signs of this nature do raise a few concerns. So, the above is what we'd want to be looking into at this stage .And its ideal to do that sooner rather then later since that way we can head off any risk of these signs progressing.
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