It is worrying that your dog is losing control of his bladder. My first thought is that it may be a urinary tract infection which is causing his symptoms, this would also explain the shaking - just like us humans, dogs also get feverish urinary tract infections.
What you should do if your dog is breathing heavily and shaking
Honestly, I would get him to the vet, to get him checked out - as something is certainly not right and he is obviously distressed.
It's the urinating that I find the most worrying, as a healthy dog doesn't do this, and I doubt he has developed incontinence so suddenly.
Other signs of a urinary track infection are:
- Cloudy urine
- Blood in the urine
- Lack of bladder control
- Pain passing urine
- Lethargic behaviour
- Not eating properly and losing weight
- Licking genitals
Dogs are like kids in a way aren't they? We can't help but worry about them and it's like having a baby in that they can't tell us how they are feeling or what part hurts.
Let me know how he is now, I really hope it was something that could be easily cured. what breed of dog do you have?