Pink Dog = Prostitute?

I found the poem Pink Dog very intriguing. My first response to the poem was a kind of unusual one. Without really looking for symbolism, I thought that the dog seemed to represent a prostitute. I mainly found this in lines 7-9, and 19-24.
In lines 7-9, it first refers to rabies and scabies. I took these to represent STDs. Then it moves on to the topic of her children. She hides them while she goes on "living by [her] wits."
Then in lines 19-24, the speaker talks about the poor treatment showed to beggars. Then it implies that "sick, four-legged dogs" will get even worse treatment. What group is out casted more than beggars: prostitutes. Then it discusses how rare it is to be able to afford these 'dogs.' If these dogs are so sickly and out casted, why would they be so expensive? Because they offer 'special' services.