I've been adding 1/4 of a hard boiled egg yolk to my 2 civvies' shared wet food once a day since early July.
I did this in response to
http://www.felinediabetes.com/FDMB/...9-6-113-pmps-215-2-5-190.179363/#post-1992492
and on the recommendation of
@Susan G & Jimmy G
I think over the past 3 weeks each civvie has: (a) produced 1 big hairball; (b) thrown up food once (stress related perhaps).
I believe this is an improvement over their pre egg yolk behavior: I was cleaning up messes every day when I decided to try it.
I'm not 100% convinced yet. Maybe I don't have the dose quite right. One civvie sometimes eats with Yum instead of the other civvie.
Yum likes being brushed so she doesn't have hairballs and she doesn't get egg yolk. Egg yolks do contain some carbs, maybe .2g per yolk.