I think your DM is both being unreasonable and reasonable here, as are you.
Your DM can feed her dogs what she likes, that's her choice as long as it doesn't contain too much salt, sugar and anything poisonous to her dogs (raisins, onions etc) BUT allowing her dogs to eat at the table or sit at the table is generally a no to me. Feeding a dog baby formula? Well, I guess it's made from cows milk anyway so to me it might be the same as feeding leftover milk/tea to the dog if you don't want to throw it away.
I would only be worried in relation to the dogs teeth and tummy with regards to this.
I don't think your unreasonable to be bothered by the above. Also you need to nyx that kissing business - dogs mouths are full of bacterias that they create antibodies for, but we don't. Your LO could get sick from this.
However, I think your very unreasonable to presume that you can place value on anyone's and any creatures life. Especially a pet. Your mother spends all of her time with these dogs and whilst there IS a line, because they are dogs, they are her family.
In fact, getting my two large dogs encouraged me to become vegan, simply because I couldn't bare the thought or anyone every hurting them and how valuable they are to me, and it started leading me to how horriblely people treat animals and view them as second class citezens. To me someone hurting a dog it akin to hurting a baby.
In a fire, I would save my dogs. However more than likely, they would be the ones to save me.
It was horrible that that dog got killed due to IS, no more and no less horrible than the people that were killed as well. No life is worth more or less than others here, it's not a competition.
And yes, I do have children also. Somedays I prefer my dogs because they don't have tantrums but I love them in different ways obviously.