Kefir — Food safety facts
Feed with care · Cats · full breakdown on the linked food page
A small amount of plain kefir can help some dogs. Never the flavoured, sweetened kind.
Short answer
Yes, a tiny spoonful of plain, unflavored kefir can be offered to a cat. Give only a small amount and make sure it’s not sweetened or flavored. Most cats tolerate the probiotic drink, but some may develop mild stomach upset. Keep an eye for vomiting, diarrhea, or changes in appetite, and contact your veterinarian if any of those occur.