Dogs and Rats? As landlords, who pays for sealing a house?

[Charles T Grimes]

This is a question about an issue I'm having with my landlord but also as a prospective landlord. 

Do dogs attract rats? 

If a rodent company inspects a house for rats and says the house needs to be sealed and they can't guarantee their work if it's not, who's responsible for paying those fees?

Back story: I just came back to California from a week and a half vacation and found rat poop in my kitchen. (I reported a rodent problem to my landlord shortly before I left and got a rodent company to look around. He put out some traps but said unless we got the house sealed they couldn't guarantee their work.) Now that I am back I got a different company to come out and look. He did a better job looking and found three areas where the rats look like they're coming into the house. He said the house needed to be sealed and it would cost $900 (Which I thought was bit high). He then said they would have to clear out the nest and clean all the poop from under the house. They are going to send me a full estimate tomorrow. I talked to my Landlord about it and he said it's because of my dog that we have rats. 

So my question is

1) Do dogs attract rats? We clean his poop daily and even spray down the rocks where he poops weekly.

2) Who should be expected to pay for the sealing of the house (the $900)? Should this fall on the tenant or landlord?

3) Who should pay for the rat removal? 

In the 7 years I've had this dog I've never had a rat infestation in my home. I've rented for 5 of those 7 years and never a problem. The 2 years I owned a home with him in it, I didn't have a problem. 

I just want to get you guys opinions.