Hi there! I am doing a long term house sit for about 11 weeks and I have been cat sitting two wonderful cats for over 3 weeks now. A week after I started my house sit, my host asked how I feel about taking care of her dog for 3 weeks towards the end of my sit. The dog is currently being taken care by her partner. During our interview before the sit there was no mention that it would be my responsibility to take care of the dog, and it wasn’t in the listing. I feel obligated to say yes and I feel bad to say no. But also it is an apartment, so there is no backyard for the dog to freely use the bathroom. And I just don’t have the time to walk the dog as much as I would like to because of my work from home schedule being quite busy. I told her that I feel someone else would do a better job taking care of him than I could and that at this time I prefer to take care of cats, but I did say I could take care of the dog if she couldn’t find another sitter.
Has this happened to anyone else before? What did you do if so?
This has happened to us a couple of times and your right, you do feel obligated to say yes. We are more experienced now and I’m not sure we would be so accommodating. In your circumstances though having a dog when you’ve agreed to care for cats is a lot to ask especially when there’s no back yard! I would tell the host that after giving it some consideration you feel it would be too much for you with your work schedule.
Awww thank you so much for your input! 
Personally I sit mainly for cats and for a good reason and they are the sits I mostly apply for. If I was halfway through a sit and put in your situation, I would without a doubt politely tell the homeowners that you sit for cats for a reason also and that sorry, I cannot take on your dog. You must stand your ground and not get taken advantage of and the HO must comply by the original deal. Might be inconvenient for them but twice as inconvenient for you. They will just have to make other arrangements. A deal is a deal.
Thanks for taking time to respond to my post! I really appreciate what you said 
You are not obliged to agree with the request. This is a big change to the terms of the sit and you can - and should - refuse if you don’t want to do it.
I would say no I am very sorry but work commitments don’t allow the time the dog needs. Be firm
I wonder if the owner has tried this before, and why she doesn’t put a dog in her listing anyway. Really cheeky of her.
You’ve accepted this sit with cats as you’re working. I can understand you’d feel uncomfortable refusing but, you must refuse. I hope she understands and isn’t rude to you.
You should feel free to say no.
If you really want to say yes, then make sure the HO has a dog walker stop by twice a day to walk the dog (make clear that you can’t due to work requirements).
But really dogs are a lot of work and you shouldn’t feel bad about just saying no.
@hippiechickpea123 it was my pleasure to give my opinion on this 
It’s fine for owner to ask and it’s fine for sitter to decline/refuse .
It should really be in the original listing , although it has happened to us that sits agreed well in advance the owners acquired additional pet before the sit . When they informed us about it we withdrew and they found another sitter .
These things should be discussed before the sit is agreed and definitely before a sit starts . Like any request that you are not comfortable with, be firm and stick to your boundaries .
If a sitter doesn’t communicate with the owner honesty about how they feel - they will feel that they are being taken advantage of . Meanwhile the hosts will be oblivious to this since they asked and the sitter didn’t express how they honestly felt.
Not sure where the situation is at currently but the sooner you contact the homeowner the better.
You may want to say something like “you know I have thought about it a little bit more and although I would like to say yes I’m going to have to decline. It’s not something I plan for in my personal schedule or my work schedule and I chose this sit for the cats.”
Completely agree with everyone! Ugh. That is rude of the Owner to even ask you to do this.
Your work gives you a perfect excuse!
Just say NO! No way. Not possible. Where does the partner live? He should get a Sitter to stay at his home with his dog!
There is a chance that this is all she heard.
It has been 2 weeks since the HO asked so it would be good to get back to her now if you are going to decline.
We have been asked on 2 occasions if we will look after a new puppy.
We did not hesitate to decline.
Owners made other arrangements and we received excellent reviews from both parties.
Be assertive and don’t feel bad
Hmmm, on re-reading your post , you made the very grave mistake of saying “you would take care of the dog if she couldn’t find another sitter”. Big mistake 
I think you have backed yourself into a corner and need to now reach out to the HO and tell her exactly what you are going to do so she can make other arrangements. By basically offering, even though you did say if she couldn’t find another sitter, she can now say well I couldn’t find another sitter and you DID say you would under those circumstances.
Be very careful in making such statements if you can’t carry through I’m afraid.
@hippiechickpea123 As others have said, you do not have to take the dog. Politely inform them that it’s a change in the agreement made and you prefer to stick to the original agreement.
Are these new homeowners?
Wouldn’t work for me as much as I love dogs many cause an allergic reaction that triggers my asthma. Hence choosing cats sits as cats don’t trigger my allergies.
I was caught out like this a couple of years ago. We specifically applied for a cat sit because we knew we would be out a great deal with a competition going on in the area. We chose a sit where the cats used a cat flap and didn’t want much contact - food, an occasional lap to sit on, someone to listen to their story for five minutes. Couple of days before it started the daughter’s dog was sprung on us. A very arthritic old dog who needed taken out at least every couple of hours. The daughter didn’t live with them. It was just convenient for her to have us look after her dog as well. We explained why we applied for their cat sit but ended up trailing this old dog around the airfield. He couldn’t have been comfortable or particularly enjoying himself but they said it was ok. We explained fully what we would be doing (husband was a judge) but they decided it was going to be ok. Never, ever again. Next time, I will say no. Yes, we pet sit. Yes, we love animals but sometimes we choose animals that are convenient for what we are doing in that area at that particular time.
I would be really peeved if this happened, and I could see leaving early. But I’d probably agree if and only if the host agreed to having a regular walker at regular times that would work with your schedule up to twice a day during that time.