Flea dirt is flea faeces containing digested blood. It can look like black-brown grit, especially around the lower back, neck and base of the tail, even when no live flea is immediately visible.
Comb over a pale surface
Use a fine flea comb gently over white paper or a pale towel. Check the comb after each pass and stop if the skin is sore. International Cat Care explains that fleas and their dirt may be found by combing; a negative quick check does not completely rule fleas out.
Use the damp-paper clue
Place collected specks on damp white paper. Flea dirt may dissolve into a reddish-brown halo because it contains blood. Ordinary soil may remain grey or black. Photograph the result and ask the veterinary practice if you are unsure rather than treating solely from an internet image.
Treat the cat and environment safely
Adult fleas are only part of the life cycle, so a control plan may also address bedding, carpets and other pets. Use only products appropriate for the species, weight and age. Never apply a dog flea product to a cat. Ask the clinic about timing when several products have been used.
Keep grooming tools separate
The Cashmere Comb contains coat-care tools, but it is not a flea-treatment kit. Clean any comb used for checking, launder bedding as advised and contact a vet about broken skin, marked hair loss or illness.
Sources and further reading
Guidance checked 13 September 2026.
