Skin problems account for almost half of visits to the vet mainly because it’s easy to see when something is wrong. Parasites, and particularly the flea, are responsible for the majority of irritating skin conditions. You may never see it, but a single flea can lead to inflammation, scratching, licking, scaling, bleeding or crusting skin, erosions, ulcers, lumps, and hair loss. Your vet, however, may diagnose many other possible causes for these skin changes.
Diagnosing the Problem
Your vet will carry out a thorough examination and use a number of methods to help diagnose the specific cause of skin disease. The simplest way to do this is to see if a particular treatment works. Alternatively, your vet may want to examine the dog’s skin with an ultraviolet light to check for ringworm, take a smear or culture for bacteria or yeast, a scrape for parasites, or a biopsy for cellular changes. Skin and blood tests, and diet and environment changes may also be used to diagnose allergic skin disorders.
Signs of skin disease
There are many basic signs that indicate that a dog is suffering from skin disease. These include scratching hair loss, pigment changes, visible lumps, inflammation, scurfy, dry scales and crusts, and wet erosions and ulcers. Most forms of skin disease have a variety of these clinical signs.
There is always a good reason for a dog scratching, but sometimes is frustratingly difficult to determine exactly what that reason is. A consequence is that the “itching” gets treated rather than its underlying causes. As well as scratching, dogs respond to itchy skin by licking, nibbling or chewing, biting, rubbing, and rolling. Itchy skin may also lead to personality changes, including loss of tolerance, irritability, and aggression. Allergies and parasites, especially fleas, are the most common triggers for scratching. Many dogs are irritated by the minute amount of anti-coagulant saliva that a flea leaves when it takes a meal. Excessive scratching can then lead to the skin becoming infected . The skin’s oil glands may also become overactive causing a crusty, smelly condition. If one of your pets has fleas, mites, or ticks, examine and treat all of your dogs and cats . Treat your home too, to eliminate immature or resting parasites.
Pimples and erosions
Skin disease caused by bacteria (pyoderma) usually occurs when the surface of the skin is damaged – through allergy, for example – allowing bacteria to multiply. Skin infections can cause pustules and papules to form: a pustule is a small, elevated, pus-filled pimple, while a papule is a small, elevated pimple filled solidly with inflammatory cells. When pimples are damaged or burst they are called erosions, and if an erosion breaks through the full thickness of skin, it forms an ulcer. Erosions and ulcers can result from:
- Acute moist dermatitis (wet eczema, summer dermatitis, hot spot) – infection that causes the surface of the skin to become moist and oozing;
- Skin fold pyoderma – bacterial growth between folds of skin -common in Cocker Spaniel lip folds;
- Puppy acne and puppy impetigo;
- Cellulitis from a penetrating wound;
- Furunculosis .
Scaling and crusting skin
If the surface of the skin becomes scaly, it can flake off as particles of dandruff, or remain, building up as calluses. Scaling is often associated with seborrhoea, a condition that results from increased activity of the skin’s oil-producing sebaceous glands. Crusts are masses of serum, blood, and inflammatory cells, produced as a consequence of skin inflammation. There are several possible causes of scaling and crusting, including:
- Bacterial skin infection (pyoderma);
- Malassezia dermatitis;
- Sarcoptic mange (scabies), resulting from infestation with sarcoptic mites ;
- Acne or “folliculitis”;
- Cheyletiella mange, resulting from infection with Cheyletiella mites;
- Leishmaniasis ï¿½ an infection of the blood caused by the pathogenic protozoa Leishmania;
- Hereditary seborrhoea (Cocker Spaniel);
Shedding and Losing hair
A dog’s coat often sheds during warm weather and regrows during cooler weather. Central heating in our homes can upset this natural rhythm, with the result that many dogs shed their coats all year round. Shedding varies between breeds: Poodles, for example, have coats that constantly grow, shedding little, while Yorkshire Terriers shed little because they have rather thin, long topcoats and negligible undercoats. Females often shed more after a season, during pregnancy, and while lactating. Hair loss, or alopecia, is different from shedding because it causes local or partial baldness in a dog. It occurs because hair fails to grow, is scratched or licked out, or spontaneously falls out. Alopecia can have any of the following causes:
- Hormonal disorders: sex hormone imbalance; underactive thyroid gland (hypothyroidism); overactive adrenal gland (hyperadrenocorticism or Cushing’s syndrome) .
- Parasitic and fungal conditions: Demodectic mange caused by infestation with Demodex mites ; ringworm .
- Environmental: pressure sores; elbow calluses; burns; reactions at the site of an injection; clipping of the coat (in spitz breeds).
- Inherited conditions: pattern baldness in Dachshunds; colour-dilution alopecia in breeds selectively bred for unusual coat colour; sebaceous adenitis in Standard Poodles; zinc-responsive dermatosis in Nordic breeds.
- Behavioural: persistent licking of an area, often caused by boredom or stress, resulting in lick dermatitis (lick granuloma or acral dermatitis).
Skin lumps and bumps
Dogs can exhibit a wide variety of skin lumps. An accurate diagnosis is essential. as some types, such as warts, cysts, and tumours, require removal by a vet. Cysts feel like hard lumps just under the skin. Warts are pink, mottled, crusty around their roots, and may be pigmented. They are most common in elderly dogs. Older dogs can sometimes develop slow-growing, soft, fluctuating, egg-shaped masses under the skin – these are often benign tumours. Lumps in older dogs should always be examined by a veterinary surgeon, however, because the could be cancerous.