My dog's poop is liquid, mushy, and looks like olive oil. Should I worry?

Hi, I would not worry if Pogi is well in himself apart from this runny poo. As you say, sometimes it can vary quite a bit according to what they have eaten or for other factors, perhaps feeling a bit under the weather etc. Keep an eye on his next poo. If he does more of these feaces, I would recommend to have him checked over and at least have a feacal test done. Try to feed him his usual diet and keep an eye on his appetite. If his next toilet looks the same you could try to offer him a bland, easy to digest diet such as chicken and rice, fish and rice or Hill’s I/D. Hope he does not give you any more worries !