Actinic disease: disease caused or worsened by sunlight.
Allergy, Allergen : see dedicated factsheets.
Alopecia: lack or loss of hair. It can be localized or widespread; focal (a single patch) or multifocal; spontaneous
(hair falls for the disease) or self-induced (coat is damaged by external trauma such as scratching).
Autoimmune disease : those in which the immune system rather than destroy external pathogens, is directed towards some normal component of the skin.
Biopsy: removal of a small sample of skin to perform a histological examination (but also cultures, PCR etc.).
Bulla: see vesicle, but larger.
Cultural examination: eg. bacteriological, mycological. A sample of hair or skin or other material is placed on a culture medium in order to isolate the pathogen.
Cyst: nodular lesion with an internal cavity lined with epithelium.
Comedone: so-called "blackhead". Hair follicle dilated and obstructed by a plug of keratin and sebum.
Cytology: through various techniques (swab, needle aspiration etc.) cells are taken from the affected skin. After being arranged on a slide and stained, they can be examined quickly with the microscope. Compared to histological examination is less precise but faster and easier to run.
Depigmentation: skin lighter in colour (white, gray) than normal.
Dermatitis: general term indicating inflammation of the skin. As such it is not a diagnosis.
Dermatoses: general term indicating a non-inflammatory disease of the skin.
Dips : topical application of a drug diluted in water. Generally they must not be rinsed.
Follicular casts: scales surrounding a tuft of hair. They are a sign of disease affecting the hair follicle.
Follicular dysplasia: congenital condition of hair follicles that are malformed.
Ectoparasites: parasites living on\in the skin (eg. fleas, mites, ticks etc.).
Endocrine diseases: involving the endocrine glands, that is those producing hormones.
Eosinophilic diseases: eosinophils are white blood cells involved especially in parasitic and allergic diseases. Frequent in cats.
Epidermal collarette : residue of a hollow lesion (pustule, vesicle), after the top broke. It consists of an alopecic center and a squamous rim.
Erythema: redness of the skin. If you press it with a finger it becomes pale.
Excoriation: superficial injury, often linear, due to trauma or self-trauma (scratching).
Exudate : pathological liquid, more or less dense, contained in a lesion or body cavity (eg. pus).
Fistula: opening to the outside of a nodule or plaque from which a pathological liquid is going out (eg. pus).
Folliculitis: inflammation of the hair follicles, the structures in which the hairs grow. The three most common causes are bacteria, Demodex mites and dermatophytes (fungi).
Granuloma: inflammatory lesion by which the body tries to isolate, to encapsulate a pathogen (eg. bacteria, fungi, foreign bodies).
Hyperkeratosis : thickening of the horny layer of the skin.
Hyperpigmentation: skin darker in colour (black, brown, bluish) than normal.
Hypersensitivity: synonymous with allergy.
Hypertrichosis: excessive growth of hair.
Hypotrichosis: hair reduction, in number or in length.
Lichenification: typical chronic lesion. On the thickened skin, it's possible to see clearly the skin typical tracks.
Macula: flat area of skin with lighter or darker color.
Nodule: solid lesion, more or less circumscribed, with size greater than 1 cm. It can be intradermal or subcutaneous.
Papule: small raised skin lesion, often reddish. It tends to evolve towards other lesions (pustule, plaque).
PCR: Polymerase chain reaction. Molecular diagnostic technique capable of detecting small amounts of DNA or RNA of a pathogen (bacteria, viruses, etc.) in an organic sample.
Plaque: circumscribed area of thickened, raised skin.
Prophylaxis: a synonym for prevention.
Pustule: small raised skin lesion, usually with yellowish apex, containing pus. In dogs and cats pustules break soon.
Scaling : detachment from the most superficial part of the skin of lamellae (scales, dandruff), generally whitish. If excessive, it is abnormal.
Scar: hairless area, usually whitish, shiny, residual of lesions that affected permanently the skin replacing it with fibrous tissue.
Seborrhea: a bit 'vague' term used to describe any situation characterized by excessive flaking or greasiness of the skin.
Self-limiting disease: that heals on its own.
Sensitivity testing : after isolating the pathogenic bacterium in a culture, various antibiotics are tested to understand which one works and which not.
Serological examinations: tests carried out on blood serum to diagnose infectious diseases.
Skin components: the skin is constituted, starting from the outside, from the epidermis (formed by a few layers of epithelial cells; without blood vessels), the dermis (vascularized, with support function) and the subcutis (containing the subcutaneous fat). Hair follicles are specialized structures in which hairs grow.
Skin glands : Sebaceous glands and apocrine sweat glands: are associated to hair follicles and produce a secretion that helps to protect the skin and keep it hydrated and soft. Eccrine sweat glands: in dogs and cats are found only in digital pads. Secrete sweat.
Skin scraping: diagnostic examination performed with a scalpel blade scraped on a lesion and then transferred onto a microscope glass in order to search for ectoparasites (eg mites).
Spot-on: pipette whose liquid is applied on the skin, usually between the shoulder blades.
Topical: drug for local use (eg. creams, spray, rinses etc.).
Trichogram: microscopic examination of hair shafts and roots. Plucking is the stripping of a tuft of hair for the trichogram.
Ulcer \ Erosion: loss of substance of the skin, superficial (erosion) or deeper (ulcer).
Vasculitis: inflammation of skin blood vessels (capillaries, arterioles).
Vesicle: small raised lesion containing a colorless liquid . In dogs and cats are rare.
Wheal: flattened, slightly raised, circumscribed lesion.
Wood lamp: a source of ultraviolet rays used to identify Microsporum canis (agent of dermatophytosis). If the test is negative, however, one can not exclude the disease.