My parson is white , and very thinly haired on his underside , he has a lovely pink belly with liver coloured blotches. If I absolutely have to I've just used Bob Martin Stay Fresh , seems OK . He has the rolling in muck habit too , and up here is Scotland we have some really black , smelly and very sticky bogs which he loves jumping into and getting a mountful as well . Unless he is completely covered |I just use and old flannel and some of the shampoo in warm water in the sink , wash of the stick bog muck , quick towel rub and a brush later.
I just use a cheapo dog brush , medium hard and a gents comb for grooming him , he loves it . I brsuh and comb him every other day as he drops a bit otherwise , and his coat looks great.He's been groomed since a pup so he will stand there all day if you'll indulge him.........
I.ve never used a sun screen product on him , he's never shown any discomfort in the sun yet.

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Properly trained, a man can be dog's best friend.