I have worked with several cats and dogs, nursing them back to health. These are older animals and they seem to respond well, although I don't exactly know what they had to start with. They do end up a lot happier and healthier afterward.
I have not had any problem getting them to take MMS . I just follow Jim Humbles advice and keep the solution diluted down to where it has around 1 PPM free ClO2. There is a slight lemon after taste, but it doesn't seem to bother either the animals or me.
I add the MMS to their water dish, and test it frequently for free ClO2. I change the water out three times a day.
We introduced some friends of ours to MMS , and they had great results with it in their household (all but cleared up chronic ringworm in one of their daughters) - they have a dairy farm. My friend then started using it with their cows, specifically for treating newborn calves who have calf scours (bacterial problem). One dose does the trick ,using the drops per weight formula! This replaces multiple doses of a veterinary medication, which is also much costlier. Even her somewhat sceptic husband is convinced of its success! Rock on MMS!