my friend has a puppy of 5 months who has been to the vets ,and has been told that the pup has white cystals in protein
what does this mean

Does the vet mean crystals in the urine?

Is it crystals and protein in the urine? The latter is due to infection caused by the bladder not emptying properly due to the former. Very young to be suffering? Is it a breed prone to this condition?

I have heard there are dog foods available that cut down on production of crystals in the urine.

do you know what food this is please and i can pass it on

Its a prescription diet...Urinary S/O...it breaks down existing crystals and stops new ones forming. Know a cat thats on it for the same problem, I presume they do a canine version. :)