Dog World, September 17 1999 – A Vet’s View, by Steve Dean

When I am desperate I always turn lo Jane Lilley, or rather to Living With Dogs, for inspiration. Recently she has been writing about cheyletiella. Looking back over past ramblings in AVV, I note that I have mentioned this parasite on occasions but I have never really devoted a whole week to describing this problem. Somewhat surprising really for I have been waging an ongoing battle with these mites for many years.

Jane called it ‘creeping dandruff’. I know it as ‘moving dandruff”, others call it ‘walking dandruff’ but whatever the term used the description is very accurate if you have experienced this infestation.

For all these terms are derived from observation of the brushings (or dander) that falls out of the coat when grooming. If you groom your dog on a large sheet of paper (good old brown paper is best), then fold it so all the brushings congregate together and then look at these bits of dried skin and detritus you may be surprised. If your dog has cheyletiella, this dandruff will move before your very eyes. It literally heaves and undulates.

Now you may not believe me, or you may think your dog cannot possibly have such an infestation, but it is more common than we think and there is a fair chance your dog is infected, especially if it is long-coated or thickly-coated. You will not see the mites in the coat for they are only just visible as specks to the naked eye.

The prevalence of this parasite is proven by Jane’s mountain of notes and correspondence on the subject. Jane is in the process of offering advice on treatment and I will comment on this subject later but first a few more facts on the mites themselves.


Cheyletiella is a parasite of cats, dogs and rabbits and collectively they are ‘fondly’ referred to as ‘Katies’ in our house. Each species has their very own type of mite but I strongly suspect that each will live happily on any of the hosts.

You may care to know the names of these pests for they are quite fascinating. Firstly cheyletiella parasitovorax infests rabbits, C blakei infests cats and C yasguri is the one we expect to find on dogs.

The parasite lives in the coat, having specially adapted feet to succeed in this environment, and goes to the skin surface only to feed. The mites live on the dead cells on the skin surface and therefore cause very little irritation. The eggs laid develop rapidly and each new generation takes about two weeks to turn into egg-laying adults. The theory is that the miles cannot survive off the host but I believe strongly this is untrue and bedding in particular can carry live mites for several days. It is thus important to clean, change or treat bedding as a part of any control programme.

When you wish to fight an enemy you need to know how it lives and survives. So now we know that the effects on the skin are minimal we cannot expect to identify infestation by symptoms alone. Put simply, many dogs carry significant numbers of these mites with no symptoms whatsoever.

Some dogs respond by producing copious amounts of dandruff, while a minority actually do react to the mite and itch, scratch and may even chew sore spots in their coat. So in any group of dogs some will appear to be badly afflicted and others will seem to have no infestation at all. Do not by fooled by this. If one dog in a pack has cheyletiella they all have it. Try the brushing test and see for yourself.

So if it causes few problems, why bother? Well one of the main group of dogs at risk is young puppies. They do tend to scratch a lot and they can look very scurfy, even though they are otherwise healthy. In adult dogs the coat may lack lustre or be relatively poor quality; not a good tiling for a show dog.

But, the real reason for dealing with cheyletiella is the effect they can have on you. If your pet has cheyletiella, so do you and your family.

Red rash

To be fair, the mite does not like living on humans for long and will leave soon after invading your skin but while they are there they can cause a nasty red rash. This is normally seen on the inside of the arms, across the belly or on the thighs – all those places where a dog or cat likes to lie. I have known many doctors look at me with astonishment when they realise the skin problem they have been treating for months in their human patients is nothing more than a transient mite infestation from the family pet.

It is true that each dog reacts differently to the mite. Some scratch, some produce a lot of dandruff, others have no symptoms at all. I have had bitches apparently unaffected but by three weeks of age their puppies resemble a snowstorm novelty like those we buy at Christmas with a winter scene in them.

So now we have established it is a good idea to rid our dogs of this infestation but there in lies a problem: what to use? Regrettably the flea dominates our attention as far as skin parasites are concerned, with ticks and mange coming second and third.

Cheyletiella has escaped the attention of those developing treatments for dogs. For it is one of the most underestimated parasitic infestations in dogs. So there are no authorised treatments for this parasite.

Jane has detailed some; from experience this parasite is sensitive to many, but not all, antiparasitic shampoos and sprays, but it is difficult to get rid of entirely. That is until the spot-on products arrived.

Since I have been using these in my dogs the incidence of cheyletiella has dropped dramatically and my three-week-old puppies no longer look like snowstorms. However not all can be expected to kill this mite.

I have just one closing message on treatment. Please try to use products that are recommended for treating other skin parasites in dogs and do not risk home remedies, human lice products or products designed for cattle and sheep. Your vet is the best person to advise you on the best choice of product for your breed of dog. Please be careful, as some of the human remedies Jane has mentioned could be very toxic for dogs, as could those for use in farm livestock.