Go to the dogs
Definition 1 of 2
Pro Tip 1/3Negative Connotation
The phrase suggests a decline with a sense of regret or disappointment. 
The local library has gone to the dogs, it's quite sad.
Pro Tip 2/3Not for People
Typically used for places or institutions, rather than individuals. 
It's a shame how the old theater has gone to the dogs.
Pro Tip 3/3Informal Usage
It's commonly used in casual conversations, not in formal writing. 
Their customer service has really gone to the dogs lately.