white dandruff

Question
i have 2 cats ages 4 and 1 both females, the 4 yr old started a white dandruff on her fur going down her back and now my 1 yr old also started this white dandruff on her fur going down her back (its mostly on the lower back on both of them) ,the 4 yr old is grey and weighs approx 17 pounds and the 1 yr old is black and weighs approx 11 pounds! what causes this dandruff ? and should i be extremely concerned about this dandruff? both my cats are very well taken care of they see our veternarian on daily basis as recommended and more(shots, exams, grooming,etc.)i frontline both of them monthly all year round even though they are inside cats. they are very healthy cats and this dandruff doesnt seem to be bothering either one of them(it bothers me more cause i see the white specks) what could cause this white dandruff on their fur and is this common in cats?  

Answer
Dandruff is OK usually. It is the dead skin coming off.  I would recommend having the cats bathed and do good combing with a flea comb to remove the dead skin.  If it continues after the skin is cleaned, then I would recommend adding Omega3 fatty acids to their diet.