Rabies is a common disease in Southeast Asia but in our personal, unqualified, non-medical opinion, the chances of you being bitten by a rabid animal in Southeast Asia (assuming you’re not provoking wild monkeys or poking dogs with sticks) are virtually nil.
Yes, there is rabies in Southeast Asia (particularly in India and Bangladesh) and it’s carried by dogs, cats, monkeys and other animals.
BUT, most of the dogs in the region are incredibly laid back. This is not Turkey, with fierce sheepdogs at every turn. Dogs in Southeast Asia tend to barely lift an eyelid from their afternoon nap as you pass by. Occasionally it’s disconcerting to see a dog start to move towards you but almost always the dog is heading for another dog across the road and not in your direction at all.
If there’s any risk, it might come from businesses with guard dogs. This is rare, but these guard dogs may come out and bark or show their teeth but we’ve never been chased by a dog in Southeast Asia or had to resort to our techniques for dealing with aggressive dogs. More often than not, the owner will come out and chase the dog with a broom if it gives you any trouble.
You do have to be a little careful walking around some cities at night. Many houses have guard dogs and together with the strays they form packs. They can be aggressive but usually just pretending to throw a rock at them does the trick.
Despite the low risk of being bitten, you may want to get a rabies injection for peace of mind. This is very expensive in Europe and North America but if you have the time in Bangkok you can get it done cheaply there.
If you are unfortunate enough to be bitten, you’ll need medical treatment as soon as possible. Being vaccinated beforehand buys you more time to get treated and simplifies the process. If you are in Cambodia or Laos, get yourself to Thailand as quickly as possible to get proper treatment or at the very least to the capital cities of Vientiane or Phnom Penh. Doctors in smaller towns may not have the correct treatment on hand.