Apart from parasites are there any other causes of skin disease in dogs?
Posted by admin in Dog Supplies Q&A, Dog Supplies Tips, tags: Diseases, Dog, Dog Advice, dog care, Dog Diseases, Dog Healths, Dog Operations, dog Q&A, dog supplies, dog supplies advice, Operations, Pet SuppliesApart from parasites are there any other causes of skin disease in dogs?
Yes indeed, there can be a number of other causes. Itching (pruritus) is one of the most obvious signs of skin disease, and although frequently caused by parasites (e.g. fleas – responsible for 90% of itchy dogs, lice, Sarcoptes, ear mites, harvest mites and some infestations with Cheyletiella or ticks), itching occurs whenever the skin is damaged or inflamed. For instance itching is one of the major signs of allergic skin diseases which develop when a previously sensitized individual encounters a particular allergy-provoking substance (an allergen). Important allergies in dogs are due to inhalation of pollens (particularly ragweed), moulds or house dust, insect bites and stings and direct skin contact with chemicals in soaps and detergents, carpets (usually the dyes), flea collars, plastics etc. Although foodstuffs are often blamed they are rarely responsible. Some dogs even develop an allergy to components of their own skin (an autoimmune disease) which frequently starts with reddening and ulceration of the mouth, lips and tongue.
Although healthy skin is very resistant to bacterial infection any damage or inflammation facilitates infection, chiefly by the pus-producing organisms staphylococci and, to a lesser extent, streptococci. Any area which is inflamed by an allergic reaction, lacerated by barbed wire or clipper blades, or which the dog bites or scratches at vigorously (e.g. following insect bites or impacted anal sacs) soon becomes infected, producing a moist, reddened area, popularly called wet eczema, that results in further itching, damage and infection. This is particularly common in breeds with a woolly undercoat .
Where the skin is thrown into folds the rubbing together of the folds and the higher moisture content within them encourages bacterial growth. Areas commonly involved are the lip folds (e.g. in Cocker Spaniels), folds on the face (e.g. in Pekingese and Pugs), screw-tail folds (e.g. in Boston Terriers and Bulldogs) and folds alongside the vulva (in obese bitches). Actual pus formation within the skin may be:
1. Superficial (= impetigo), with the formation of small pus-filled ‘ spots’ (pustules), usually on the underside of the belly in puppies.
2. Deep (= furunculosis). Although this deep infection can occur in any region, favorite sites are the chin (acne, seen especially in short-coated breeds), the head (puppy-head disease, affecting short-coated pups under four months old), the nose (especially in Collies and German Shepherd Dogs), the pressure points on the elbows and hocks of large breeds,around the anus (chiefly in German Shepherd Dogs) and between the toes of short-coated breeds. In the last-named condition, the delicate skin between the toes responds to being punctured by the coarse hairs by forming large fluid-filled swellings termed ‘interdigital cysts’ (something similar in humans is seen on hairdressers’ hands). Severe cases are associated with minute cuts inflicted by sand, gravel, clinker or metal turnings (e.g. suffered by guard dogs in factory yards).
Although itching is common there are some skin disorders in which it is characteristically absent. In certain hormonal disorders there is a loss of hair, which is identical on both sides of the body (i.e. they appear as mirror images), occurring without any skin irritation. This is seen in hypothyroidism (lack of thyroid hormones, especially in Retrievers), Cushing’s syndrome (excessive corticosteroid output – especially in small terriers, Poodles and Boxers), a markedly increased or decreased female sex hormone (oestrogen) output in bitches and oestrogen production in male dogs producing feminization. The usual cause of the last condition is an oestrogen-secreting tumour of the testicle, and it also results in enlargement of the nipples and makes the dog attractive to other males. These hormonal disturbances are not in any way contagious.
Skin can also be involved in the growth of tumours and at times is affected by very bizarre conditions. Examples of the latter include cutaneous asthenia (rubber puppy disease) in which the skin can be stretched to extremes but also tears very easily, and canine icthyosis (fish-skin disease) where much of the body surface is covered with grey scales and feather-like projections.
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