The information below is only our experience. We are not veterinary surgeons so please bear this in mind and seek help from a vet if you are at all worried.
Although some elderly birds develop some slightly rougher or raised scales on their legs usually the cause of this is a mite called Cnemidocoptes mutans or the "scaly leg mite". The nasty creatures burrow under the scales and live there. As well as the pheasant having raised scales the legs or feet may look crusty which is due to the build up of the mites droppings and also the bird's skin as the body produces an abundance of extra cells to try and heal. If the infestation is particularly bad the legs might bleed either from the damage done by the mite or because the bird has been pecking its legs to try and rid itself of the discomfort. If treatment is not carried out the bird will eventually become lame and extremely distressed.
There are a few remedies which can be bought specifically to kill or repel scaly leg mites. The ones I know of are:
Johnsons Scaly Lotion - This is sold for cage birds rather than poultry or game birds so may not be suitable if the bird's eggs are for consumption. We have used this lotion ourselves in the past and it worked very effectively. It is only a small bottle but there is plenty to treat a bird to a few treatments. We repeated the treatment a week after the first dose just to make sure the mites did not quickly return but the bird made a very quick recovery and showed no sign of irritation since the first dose was administered.
Net-Tex Just for Scaly Legs - This is a spray which is licensed for poultry and kills the mites on contact. Treatment should be repeated 5 or 6 days later to kill off any newly hatched mites before they mature.
Barrier Scaly Leg Spray - An effective repellent for game birds as well as poultry and cage birds. This will not taint eggs so is fine to use if the eggs are to be eaten. Like the other treatments the spray should be reapplied a second time to break the lifecycle of the mites.
Over the years we have read or heard many ideas for treating scaly leg but some old remedies seem to be rather severe. I would NOT wish to try diesel or creosote on our birds which I dare say will kill the mites but must be pretty awful for the bird. There are however some solutions which fare better and will be easily available. One of the methods of killing the mites is by suffocation (of the mites not the bird) and vaseline (petroleum jelly) seems to be the most widely used emollient for the job. Smeared on the affected areas it sooths the bird's skin and at the same time kills off the mites. I feel however that there are other creams and lotions which can do a better job than petroleum jelly mainly due to the fact that the vaseline does not last long before it needs to be reapplied. I have on many occasions used "sudocrem" antiseptic cream for us and some of our animals. It is a first class barrier and will stay on the bird's legs much longer than the petroleum jelly. It will also soften the skin and promote healing. This is meant for human use (it's sold among baby items for nappy rash among other things) and not for birds but compared with many other suggestions I have heard it would make a far better alternative.
It is always good practice to make sure the aviary is properly cleaned and the shelter (including the perches) dusted every now and then with an insecticidal powder. We always have "ecomite powder" handy. This can be used directly on the birds and in their pen. It will kill a selection of ectoparasites including lice, mites, ticks and fleas. The powder can be dusted on or mixed with water and brushed or sprayed. We have found this to be every bit as good as more expensive brands and we would certainly recommend it.
If anyone would like to share their own experiences dealing with scaly leg mites please don't hesitate to get in touch.
Matthew Robson has been in touch, with us, with the following tips for controlling parasites:
The best thing to do to clear Scaly leg is to put on a liberal coating of Swarfega and rub it well in. The condition will be totally gone and healed, within 2 weeks, with no sign it was ever there. I have also found that using Diatomacious earth against red mite on the roosts and in the sheds will clear up this problem completely. It can also be used to dust the birds against Red mite and lice and will clear up the severest of cases.