The skin and hair coat in pets have several roles and functions and depending on their condition it can be used as an indicator of a general health. As there are numerous reasons of skin diseases in pets the diagnosis is often difficult and response to treatment also takes time for evaluation. Pets, especially the dog and the cat are prone to a number of different skin diseases. All types of skin affections, particularly in the dog, they are often mistakenly referred to by laymen as either mange or eczema. Skin affections that affects the skin of pets can be positioned into two categories i.e., primary and secondary skin disease. Primary skin diseases are those which directly affects the skin, i.e. tick, flea and mange hypersensitivities. Secondary diseases are those which initially involve other organs and thereby it affects the skin i.e. hypothyroidism. The diagnosis and treatment of skin diseases can be difficult and time consuming. Thorough determination of the cause should be done by carefully recording history of the case and by using the modern diagnostic tools before treatment. Frequently many skin diseases require lifelong treatment.
The following are some of the common skin affections/diseases that affects the skin most commonly. The current review paper represents brief description, diagnosis and treatments of common skin affections.
Healthy pets do not easily develop skin infections. The host defence system -cutaneous barrier and the immune system, provide prompt protection but if an infection takes place, either one or both of these may be defective. Physical trauma is one of the most common cause for compromised barrier function and common consequences of such physical trauma are deep tissue infections and abscesses. In puppies and young dogs, the immune system may not be completely matured in puppies and young dogs which facilitate diseases like impetigo, mostly when nutrition is suboptimal or severe endo-parasitism occurs. Apart from these, stress is also one of the immunosuppressive factor and it can also contribute to the development of skin infections.
Superficial Skin Infections
Superficial bacterial infections of the skin are common affection, especially in the dogs. It can be classified as mucocutaneous pyoderma, impetigo and superficial folliculitis.
Mucocutaneous Pyoderma : It is a bacterial infection characterised by erythema, depigmentation, oedema and/or crusting of the mucocutaneous areas of skin. There may be the presence or absence of pruritus but it is not a useful clinical indicator for differentiation of possibility of hypersensitivities or endocrinopathies as predisposing factors.
Impetigo : Impetigo in the dog is caused by bacteria i.e. Staphylococcus organisms which is characterised by pustules and epidermal collarettes affecting the thinly haired ventral areas in young dogs.
Superficial Folliculitis : It is one of the most common bacterial infections of the dogs characterised by an infection of the upper part of the hair follicle with S. intermedius. The typical lesion is a small pustule with a hair protruding from its centre which is frequently preceded by a follicular papule. Subsequently, there is loss of hairs and pustules are converted into epidermal collarettes.
Deep Skin Infections : Deep pyodermas are serious bacterial infections which involves deeper tissues. Deep pyodermas may be a progression of a superficial infection that was inappropriately or insufficiently treated or did not receive any therapy. Causative organisms extends to the deep hair follicle of the skin and along with the inflammatory response, it causes a break through the follicular epithelium into the dermis and subcutis layer of skin. Deep skin infections are often found to be associated with an underlying disease that is responsible for a break down in the host immune defence system. Besides antimicrobial therapy, this disease must be identified and treated to attain remission of the infection. If at all, a deep skin infection is localised, the most common cause is trauma, i.e. a bite or a foreign body.
Folliculitis, Furunculosis and Cellulitis : These are usually an extension of a superficial skin infection. An underlying causative agent/disease is usually present which needs to be diagnosed and treated for achievement of good long term results.
Subcutaneous Abscesses : Subcutaneous abscesses are frequently found in cats and often d as a result of bite wounds. Subcutaneous abscesses are rare in dogs and apart from bite wounds they are often caused by foreign bodies.
Bacterial Skin Infections (Pyoderma) : Bacterial skin affection/diseases often reffered as “pyoderma” which are the most common cause of skin affection in dogs. Pyoderma includes a wide range of bacterial infections which often leads to the formation of pus. Pyoderma also vary in their severity. All areas of body can be involved, but most cases are confined to the trunk area. Pyoderma can be classified based on the depth of lesions and the distribution pattern along with the clinical and histopathological features which is necessary for establishing a prognosis and selecting a proper treatment. This classification (Table 1) allows us to distinguish surface pyoderma and superficial pyoderma from deep pyoderma.
|Surface/Superficial Pyodermas||Bacterial overgrowth syndrome Impetigo Folliculitis Skin fold pyoderma (intertrigo) Mucocutaneous pyoderma|
|Deep Pyodermas||Cellulitis Furunculosis|
|Pseudo-pyodermas||Pyotraumatic dermatitis Juvenile cellulitis Eosinophilic furunculosis Idiopathic sterile granulomatous panniculitis|
Causes: Staphylococci are one of the most common organisms found in pyodermas of dogs.
- Itchy, yellow pustules are often observed early in the disease
- Reddened and ulcerated skin.
- Dry, crusted areas appear as the condition progresses
- Loss of hair in the affected areas and an odour.
- Based on the case history and appearance and location of the lesions.
- Culturing the skin scrapping and conduct sensitivity tests to determine which antibiotic will be effective in treatment.
- Most bacterial skin infections in dogs are secondary to another disease such as parasitism, allergies, endocrine (hormonal) disorders or abnormalities in the immune system.
- It may also be necessary to do blood tests, allergy tests or skin biopsies to achieve a complete diagnosis.
- Initial treatments may involves removal of the hair in and around the lesions
- Washing of the whole dog with antibiotic shampoos such as benzoyl peroxide
- Careful drying and the application of an antibiotic ointment to local lesions
- Bandages or a protective collar which prevents the dog from mutilating the lesions may be applied.
- Some pyoderma involving skin folds can require corrective surgery.
- It may be necessary to continue treatments such as antiseptic shampooing, antibiotic ointment applications and giving antibiotics orally at home.
Fungal Skin Infections (Ringworm): Fungal skin infections involves Malassezia spp., Dermatophytosis (Ring Worm) and dermal coccidioidomycosis.
Cause: The fungal skin infections are caused primarily by two major species of fungi: Microsporum and Trichophyton. The fungal skin diseases resulting from these fungi are commonly called as ‘ringworm’. The most commonly affected area are head and legs, although the disease may spread over other parts of the body if not properly treated.
- Most commonly in young dogs.
- The fungi live in dead skin tissues, hairs and nails.
- Hair loss, usually in circular patches may appear.
- The center of the patches may have a dry, crusty appearance.
- Diagnosis can be done by culturing of the organisms, microscopic examination of skin scrapings and blood tests which identify antibodies to Coccidioides immitis.
- Diagnosis is done on the basis of appearance of the lesions, the history of their development and the age of the dog are all helpful in diagnosing ringworm.
- A Wood’s Lamp Test (ultraviolet light) can be used to help diagnose the Microsporum species only.
Treatment: Treatment involves topical and systemic antifungal drugs and antifungal shampoos and antifungal rinses. The hair around the lesions is clipped and special fungicidal shampoos or fungicidal rinses are used for bathing the dog. Topical lime sulfur and mandatory systemics should be administered for the treatment.
Allergies: An allergy is a hypersensitivity reaction to ‘allergens’ or ‘antigens’ (allergy causing substances). Allergies in dogs are common. Dogs (like people) can develop allergies at any age and the signs can appear quite suddenly. The most common allergy that dogs develop is the flea saliva. The presence of even single flea on these allergic dogs causes intense itching. Most allergens are inhaled but a very few are the contact type i.e. an allergy to wool. Some allergens are found in food (most commonly in corn, wheat, soy, beef, and dairy products).
- Allergens or antigens.
- Flea Bite/saliva
- Atopy (atopic dermatitis, allergic inhalant dermatitis) is a pruritic (itchy) skin disease dogs develop in response to inhaled particles such as house dust, molds and pollens.
- Contact allergy: Rarely, dogs can be allergic to chemicals contained in soaps, waxes, carpets and flea collars.
- Also, some dogs are allergic to insect bites and stings.
- Itching – the primary sign of allergic skin diseases in dogs.
- Red and moist in patches called ‘hot spots’ in the affected areas of the skin.
- Itchy skin, nasal and eye discharges and sneezing
- Digestive disturbances
- Pus and dried crusts are apparent if a bacterial infection is also present.
- Red bumps and pimples.
- Based on case history
- Intense itching
- Response to treatment (flea control) is often useful tool of diagnosis of flea allergy.
- Allergy testing is also used to help choose immunotherapy.
- Allergies can be controlled in most cases with few ‘cured’.
- Antihistamines and corticosteroids may be used by your veterinarian to give your dog relief from the intense itching.
- In most cases this will stop the self-mutilation.
- The owner will be instructed to give corticosteroid tablets in decreasing dosages for a few months. Corticosteroids are potent drugs and should not be used carelessly or for long periods of time.
- Another approach to allergy control is hypo sensitization (immunotherapy).
Parasitic Skin Diseases : Parasitic Skin Diseases are mainly caused by ectoparasitic infestation. Parasitic Skin Diseases are also one of the commonly found skin affection in pets.
Cause: Ectoparasites (external parasites) include mites, fleas and ticks. Fleas are the most common parasitic skin disease found in dogs. Mange is another type of skin disease which is caused by mites. There are two severe types of mange: sarcoptic mange and demodectic mange. Ear mites, lice, and ticks are other parasites that affect dogs. Their presence irritates the dog which leads to self-mutilation. These parasites break the barrier formed by the skin and allow bacterial infections to occur. They also may lead to allergic conditions.
- Sarcoptic mange causes intense itching, loss of hair and crusting of the skin. A dog’s ears, front legs, chest and abdomen are most often affected by sarcoptic mange. Demodectic mange can cause itching.
- Reddened and scaly skin and hair loss occurs in round patches resembling ‘ringworm’.
- Scratching of ear as ear mites cause severe irritation in the ears.
- Ticks, lice and fleas may transmit other diseases in addition to causing irritation.
- Diagnosis is achieved with gross observation and microscopic examination of skin scrapings.
- A skin scraping test is always performed to aid in identifying parasites.
- Mange is often suspected on the basis of the case history and the appearance and location of the lesions. Ear mites, who are barely visible to the naked eye, appear as small white objects. The black debris commonly seen in the ears of dogs with ear mites is a combination of dried blood, normal ear wax and discharges from Inflammation.
- Lice, fleas and ticks can also be seen by close examination of the dog’s skin.
- Treatment depends on the parasites present and include antiparasitic drugs and antiparasitic shampoos, rinses and antiparasitic spot ons.
- Mange is treated by clipping the affected areas and washing them with an antiseptic.
- Antimite dips are often necessary and may be used weekly or biweekly for several months. The dog’s eyes should be protected with mineral oil or eye ointment and the ears plugged with cotton before dipping.
- Lice, ticks and fleas must be killed on the dog and in the surrounding environment of pets with insecticides. Dips, shampoos, flea collars, sprays, powders, foams and foggers containing insecticides are available in market can help to control these parasites.
Hormonal Skin Diseases : Skin diseases are also caused by hormonal abnormalities in dogs. Hormonal skin diseases are difficult to diagnose. The thyroid gland, adrenal glands, pituitary gland, testicles and ovaries all produce hormones. If it is excessive (‘hyper’) or deficient (‘hypo’) then these hormones may produce changes in the skin and hair coat of pets. Majority of hormonal problems that affects the skin produce loss of hair that is evenly distributed on each side of the body. The skin may be thicker or thinner than normal and there may be changes in the color of the skin coat. Hormonal skin diseases are usually not itchy. When any of the hormone-producing glands does not work properly then they affect other body functions besides the skin.
Hormonal skin diseases in pets may be much more serious than a ‘skin problem.’ Some causes of hormonal skin disease such as hypothyroidism and adrenal gland problems can be diagnosed by special blood tests and can be effectively treated. Others can be more difficult to diagnose and even to treat. Skin changes related to the sex hormones can be successfully treated with surgical manipulation.
Other Skin affections
Hot Spots or Acute Moist Dermatitis: Hot spots generally occurs as a result of self-trauma and they often result in infection that occurs as your dog tries to relieve itself from itch. Treatment involves thorough cleaning and application topical and systemic antibiotics and anti-inflammatory agents.
Autoimmune Skin Diseases: There are several autoimmune skin diseases and the basis of diagnosis of such conditions is surgical biopsy. Treatment includes combinations of dietary supplementation, steroids and immune modulation drugs.
Conclusion: A wide range of organisms like bacteria, mites, flea, ticks, lice as well as allergens cause skin infection, irritation and inflammation. In most cases dermatological cases amongst the most difficult and most expensive to diagnosis and treat. Prompt diagnosis of the skin affections and their effective treatment along with control strategies should be implemented to make animal free from any skin affections. In the end, the most important key is to maintain the utmost comfort and high quality of life for the pets, especially to the dogs and cats. By doing this we can maintain a good health of our pets.