Demodicosis is a skin disorder of dogs associated with higher than normal populations of demodectic mites. It is caused by Demodex canis, a host specific mite and a normal inhabitant of canine hair follicles. The mite is not spread from dog to dog but from the lactating bitch to sucking pups by direct contact during the first few days of a pups life. The mite will cause skin disease in some dogs but not
in others. The reason for this is unknown.
Possible causes include: (a) immunosuppression, i.e. unable to fight infection that may be hereditary, (b) changes in hormone levels as demodicosis frequently occurs around 6 - 9 months of age, a time when puppies are becoming sexually mature. Also we can see the disease after the first season
of a bitch.

Localised demodicosis
This form is mild with areas of non-itchy hair loss especially around the face and forelimbs 90% of these cases get better without treatment. This is common in young dogs.

Generalised demodicosis

Juvenile Onset
In about 10% of cases the condition becomes generalised affecting most or the whole of the body. These cases develop secondary bacterial infections which will cause the dog to scratch. The mite on its own doesn't cause itching. Dogs are frequently depressed and off their food. Between 30-50% of dogs with generalised demodicosis under a year of age recover spontaneously.

Adult Onset
This is a rare form of the disease that occurs in older dogs over 4 years of age with no prior history of demodicosis. Underlying causes include internal disease, for example cancer or dogs receiving cortico
steroid, used in allergic skin disease but they do depress the immune system allowing the mite to proliferate and therefore cause skin disease.

Treatment
First of all we don't want to use steroids as they depress the immune system making things worse, as I have already pointed out. Secondly, we should try to identify and, if possible, correct any underlying causes, such as steroid treatment or cancer. Because of the hereditary nature of the disease, dogs
with generalised demodicosis should be castrated or spayed. Some veterinary surgeons argue that even dogs with self curing localised demodicosis should not be bred from, but I strongly disagree for two reasons. First, these dogs will get better on their own and secondly, if we as Staffordshire Bull Terrier breeders were to do so, our gene pool would be so small that the breed would soon become extinct
as demodicosis is so common within our breed. I have a problem within my breeding but I have never had a case of generalised demodicosis!! I try to use stud dogs that have little or no history of
demodicosis to decrease the incidence of demodicosis within my breeding.

Localised demodicosis is not treated in most cases as 90 % get better on their own. In generalised demodicosis a solution called Amitraz (Aludex) diluted in 1 part amitraz to 100 parts water is applied to the dog's body every 7 days until skin scrapings have shown no mites. Prior to its use benzoyl peroxide
(Paxcutol) helps to remove scale, crust and pus. Ideally dogs should also be clipped allowing better skin contact. Oral antibiotics are given to treat the secondary bacterial infection. Treatment can last for
months especially when the feet are affected. Ivermectin is not licensed for use in dogs only on farm animals and some small mammals and can be fatal especially in Collies, Shelties and their crosses. However, if amitraz doesn't work then we will consider using ivermectin.

Diagnosis
History, i.e. age, breed and symptoms non itchy hair loss are helpful, but for a definite diagnosis deep skin scrapings or even multiple skin biopsies are necessary so that the mites can be seen under a
microscope. In adult onset the demodicosis one always looks for an underlying condition.

To sum up. Demodicosis is a common skin disease in Staffordshire Bull Terriers. We should not breed from dogs where all or most of the body is affected. If we do see localised demodicosis in our litters, as
I have seen in mine, then we should try to use stud dogs that have no history of the disease or a very limited history. It is my professional opinion that if we stop breeding from dogs with mild self-curing
localised demodicosis then the gene pool within our breed would be so small that we would loose our best breeding lines, if not the breed as a whole. This is because the mite is a normal skin inhabitant of the vast majority of dogs.                                                         

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