Should my boyfriend help me pay??

So my dog is getting a procedure done for about $1700. I have been living with my boyfriend for about a year now and we are obviously serious. He treats the dog like his but the dog was mine before I got together with him. My question is should I ask him to help me pay for this a little bit? I’m not asking for him to foot the bill, or even half, just wondering if it’s accceptable to help. We are more than old enough to split bills and everything we have been doing for a year. And just for reference I pay for everything for the dog that he’s needed, and never ask or expected help..food, vaccines, anything. Now with this large bill I am wondering if this is acceptable to ask for help or opinions if he should help me anyway..