I brought home a friends cat that had just had 7 kittens the night before, 6 of them have died in the past 5 days. Many of which I believe staved due to lack of milk. May had white tongues with black on the tip?? The one left seems to be doing OK I've been helping with feeding kitten formula but now his tongue has black on the tip should I be worried?? I think they were born premature and moma didn't have enough milk to care for them all. He seems OK but the tongue worries me, black on the tip and it seems too big for his mouth, should I be worried or concerned?? Should I take him and moma to vet?? Can't really afford it but don't want to lose him please help

Black on a kitten's tongue could mean an immune deficiency, which makes sense. Would suggest a vet visit.