Canine generalized demodicosis (also known as demodectic mange) is a skin disease caused by a parasitic mite, Demodex canis, which, although present in small numbers in the skin of almost all
dogs, in some individual multiplies too much, causing the lesions.
The reasons of this increase in the number of mites are not yet well understood but they are certainly related to a malfunction of the immune system of the affected dog. This defect is generally genetically based in the juvenile form (appearing before two or three years of life), while in adults is associated with debilitating diseases.
The disease is not contagious for other dogs nor for humans.
Demodex mites live in the hair follicles and damage them, resulting in hair loss (alopecia) in smaller or larger areas of skin. Other symptoms are represented by erythema, scaling, crusts and comedones.
Very common is the presence of a secondary bacterial infection (pyoderma) that greatly worsens the clinical picture.
The diagnosis is made by the veterinary surgeon through skin scraping, hair plucking (examination of the hair roots) or, rarely, biopsy.
Therapy: generalized demodicosis is a disease sometimes difficult to cure. It requires a long and challenging treatment (on average 3-4 months). However, in the last years a new family of oral drugs appeared in the market, simplifying a lot the therapy.
It 's a big mistake discontinue therapy too early (before two negative skin scrapings one month apart). Checks should be made regularly.
In addition to the acaricidal drugs, the secondary bacterial infection, if present, should be treated .
In adult-onset forms we must also search for any other underlying diseases.
In genetic juveniles- onset forms, dogs should not be mated to avoid the inheritance to the puppies.
If the therapy is not effective we can change the drugs protocol or switch to another drug.
After healing is appropriate to check the dog regularly (relapses).
Practical tips about treatment:
Amitraz dips : Long-haired dogs must be clipped. It is useful first to use an antibacterial and softening shampoo (to remove crusts), then the dog is rinsed and dried. The solution of amitraz must be freshly prepared. The environment must be well ventilated. People making the dip should wear gloves (people with diabetes and asthma must be excluded). The dog must be kept with his feet immersed in the solution. To avoid licking, put an elisabethian collar (essential if it is a cat) or a muzzle. It should not be rinsed. Dry the dog with towels. In the following hours keep the dog warm (especially if small ).
Ivermectin, milbemycin, moxidectin: before starting therapy rule out cardio-pulmonary filariasis. Ivermectin is a bit bitter > give it with something sweet.
NB: This group of drugs (especially ivermectin) can cause serious neurological side effects in certain breeds of dogs (eg. Collie). Always follow the directions of the veterinary surgeon and refer him promptly any problems arising.