China recently issued a one dog per family rule and no large dogs or "dangerous dogs."  The reason supposedly is rabies.  Only 3% of China’s dogs are vaccinated against rabies and rabies killed over 300 people in September alone in China.

Beijing issues 1 dog per family rule – Yahoo! News.

[Note that my SO and I would not have been able to move in together for years after we did, if this rule was in effect in the US.  Neither one of us would have given up our dog!]