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| ==Introduction== | | ==Introduction== |
− | Seborrhea is characterised by a defect in keratinisation or cornification. This results in increased scale formation, a greasy skin and hair coat and often secondary inflammation and infection. | + | Seborrhea is characterised by a '''defect in keratinisation or cornification'''. This results in increased scale formation, a greasy skin and hair coat and often secondary inflammation and infection. |
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| There are large amounts of free fatty acids and cholesterol and decreased amounts of diester waxes in surface lipids which lead bacterial populations to become pathogenic [[:Category:Staphylococcus species|coagulase positive staphylococci]] | | There are large amounts of free fatty acids and cholesterol and decreased amounts of diester waxes in surface lipids which lead bacterial populations to become pathogenic [[:Category:Staphylococcus species|coagulase positive staphylococci]] |
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− | It is a chronic disease affecting mainly dogs, but also sometimes cats and horses. | + | It is a '''chronic disease''' affecting mainly dogs, but also sometimes cats and horses. |
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− | ===Primary idiopathic seborrhea===
| + | ==Primary idiopathic seborrhea== |
− | This is a common inherited skin disorder seen most frequently in Cocker Spaniels. Basal epidermal cells in affected dogs undergo accelerated cellular proliferation and turnover. | + | This is a common '''inherited skin disorder''' seen most frequently in '''Cocker Spaniels'''. Basal epidermal cells in affected dogs undergo accelerated cellular proliferation and turnover. |
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− | There is an increase in the number of actively dividing basal cells, a shortened cell cycle, and a decreased transit time to the stratum corneum (7-8 days compared with 21-23 days). Hair follicles and sebaceous glands are also affected. | + | There is an increase in the number of actively dividing basal cells, a '''shortened cell cycle''', and a decreased transit time to the stratum corneum (7-8 days compared with 21-23 days). Hair follicles and sebaceous glands are also affected. |
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| + | Abnormal keratinisation begins from a '''very early age''' and tend to worsen with time. |
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− | *Microscopically:
| + | ==Secondary seborrhea== |
− | **Hyperkeratosis distending follicular ostia causing papillary appearance
| + | Secondary seborrhea occurs due to an '''underlying disease''' predisposing to excessive scale, crusting and oiliness. |
− | **Parakeratosis at edges of follicular ostia
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− | **Congested, oedematous dermal papillae
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− | **Spongiotic epidermis with leukocytes
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− | ===Secondary seborrhea=== | + | The most common causes are endocrinopathies and allergies, but other diagnoses should be considered. |
− | *Develops secondarily to many types of disease (''e.g.'' [[:Category:Integumentary System - Parasitic Infections|ectoparasites]], [[:Category:Integumentary System - Mycotic Infections|fungal infections]], [[Endocrine effects on the skin - Pathology|endocrine disease]], internal disease or allergy)
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− | *Microscopically:
| + | For animals '''under the age of 1''': demodecosis, cheyletiellosis, scabies, nutritional deficiencies, icthyosis, epidermal dysplasia, food hypersensitivity and atopy. |
− | **Hyperkeratosis and/or parakeratosis of follicles and epidermis
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− | **Lesions relevant to the other disease
| + | In animals up to 5, '''allergy''' is the most common cause of seborrhea. |
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| + | In animals over the age of 5 an '''endocrinopathy''' or neoplasia become more likely. |
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| + | ==Clinical Signs== |
| + | Clinical signs are very similar between primary and secondary seborrhea cases. |
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| + | Mild forms of seborrhea show: '''greasy scales''' around the nipples, lips folds and external ear canal. |
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| + | More severe forms show: more severe and generalised lesions, with multiple coalescent scaly or crusty pruritic patches, digital hyperkeratosis and dry, brittle claws. '''Otitis''' can be a prominent feature in some cases. |
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| + | The degree of pruritus is useful in ruling out certain diseases. |
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| + | If the '''pruritus''' is minimal, endocrinopathies, neoplasia and demodecosis should be considered, and allergies and scabies become less likely. |
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| + | Seborrheic dogs are prone to developing '''secondary infections''' with bacteria and ''Malassezia'' and this can have a marked effect on pruritus, which can become severe. |
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| + | Other '''systemic signs''' may be present if a systemic disease is causing the seborrhea, such as polyuria/polydipsia, abnormal oestrous cycles, the influence of diet, the environment or the season. |
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| + | ===Diagnosis=== |
| + | The diagnosis of primary seborrhea is made '''by exclusion'''. |
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| + | A thorough physical and dermatological examination is made to attempt to identify an underlying cause. |
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| + | '''Cytology''' should be performed on the affected area to determine the bacterial and fungal load. This will help determine the best treatment. |
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| + | Other tests include: '''deep skin scrapings, fungal culture, impression smears and coat brushings'''. |
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| + | '''Haematology, biochemistry and urinalysis''' may be helpful in identifying any systemic problems. |
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| + | '''Biopsies''' are recommended, and for primary seborrhea, will show a hyperplastic superficial perivascular dermatitis. There is usually orthokeratotic or parakeratotic hyperkeratosis, follicular keratosis and apoptosis of keratinocytes. |
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| + | There may be inflammation, and parakeratotic caps overlie oedematous dermal papillae. |
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| + | Bacteria and yeast are numerous at the surface and evidence of secondary bacterial infection is common. |
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| + | ===Treatment=== |
| + | Primary seborrhea cannot be cured, but it can be managed in most dogs. |
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| + | In dogs with secondary seborrhea, the effort should be placed on curing or managing the underlying disease. |
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| + | In all cases, '''antibiotics or an antifungal''' may be necessary at first to cure secondary infections. Cytology can be performed during treatment to check for any recurrence of infection. |
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| + | Shampoos can also be used to decrease the bacterial load, aid pruritus and normalise the epidermal turnover rate. |
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| + | The mainstay of therapy is the use of '''antiseborrheic shampoos and moisturisers''': |
| + | :'''Keratinolytic''' products: salicylic acid, tar, selenium sulfide, propylene glycol, fatty acids, and benzoyl peroxide. These lead to sloughing of surface keratinocytes and reduce the scale. |
| + | :'''Keratinoplastic''' products: tar, sulfur, salicylic acid, and selenium sulfide. These slow down epidermal basal cell mitosis. |
| + | :'''Emollients''': lactic acid, sodium lactate, lanolin and oils. These reduce water loss from the skin and maintain hydration. |
| + | :'''Antibacterial''' agents: benzoyl peroxide, chlorhexidine, iodine, ethyl lactate. |
| + | :'''Antifungal''' agents: chlorhexidine, sulfur, iodine, ketoconazole, and miconazole |
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| + | Shampoos usually combine different agents, and the selection should be made on the basis of the scaliness and oiliness of the coat. |
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| + | Cleansing and emollient agents are usually sufficient in mild cases. |
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| + | Sulfur, salicylic acid and benzoxyl peroxide should be used in more severe cases needing agents with keratinolytic, keratinoplastic and antimicrobial effects. |
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| + | In most cases the '''prognosis is good''', but treatment is usually complex and involves alot of input from both the vet and the owner. |
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| + | {{Learning |
| + | |flashcards = [[Small Animal Dermatology Q&A 19]] |
| + | }} |
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| + | ==References== |
| + | Harvey, R. (2009) '''A colour handbook of skin diseases of the dog and cat''' ''Manson Publishing'' |
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| + | Muller, G. (2001) '''Small Animal Dermatology''' ''Elsevier Health Sciences'' |
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| + | Merck and Co (2008) '''The Merck Veterinary Manual''' ''Merial'' |
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| [[Category:To Do - Helen]] | | [[Category:To Do - Helen]] |
| + | [[Category:To Do - Review]] |
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| [[Category:Integumentary System - Pathology]] | | [[Category:Integumentary System - Pathology]] |