A turn for the worse?

Gail here:

At times like these, ordinary domestic troubles can seem trivial compared with dreadful events reshaping our geopolitics, but small sadnesses at home are still all too real. 

"Behaviour changes observed in twelve year old dog, deaf and living with bladder cancer" is never going to make the headlines anywhere but this blog. 

So what's been happening with Bertie? 

First and most noticeable - during our morning walks in Duthie Park he often now seems disorientated - running off in random directions where formerly he would, more or less, follow a set circuit around the park perimeter. Also, he occasionally bumps into things, and I suspect that his eyesight, which long has been weak, has deteriorated further. But I also wonder what's happening in Bertie's brain. 

In the house, especially towards the end of the day, Bertie can be unsettled, agitated, often just standing there, head and tail drooping, looking unhappy. Last night, while I was preparing supper I heard Bertie barking in the study (unusual in itself) and found him yapping at the empty armchair, as if I was sat there and he wanted something. When Bertie lies down, he manoeuvres himself into position very, very tentatively, as if to avoid pain in his abdomen. He rarely seems relaxed in the car nowadays - I think the vibration causes him discomfort. 

Occasionally, when trying to pee, and at other times, a tremor in his rear legs starts up and persists for a minute or two. 

Bertie is still eating well, digesting his food and maintaining his weight. He's also still keen to go out for walks, and at night, wearing his 'male dog belly band' he sleeps peacefully on my bed. 

What best to do for my dear wee chap?