Small Animal Dermatology Review

Flashcards from Small Animal Dermatology Lecture Notes

What is the skin?

Largest organ in the body

What are some key learner issues in small animal dermatology?

Factors important in creating a differential diagnoses list, signalment importance, lesion identification based on description, tests in the “minimum data base,” issues diagnosed with surface cytology, ringworm culture follow-up, skin biopsy considerations.

What is the 'bricks and mortar' analogy in epidermal anatomy?

Keratinocytes (structure, protection, dehydration prevention) and intercellular lipids/proteins (hold keratinocytes together, create water-tight seal, inhibit infection).

What are the major cell types of the epidermis and their functions?

Keratinocytes (keratin production, lipids, enzymes), Langerhans cells (immune surveillance), Melanocytes (pigment, solar protection, immune response, antioxidant).

What are the layers of the epidermis?

Stratum corneum, Stratum granulosum, Stratum spinosum, Stratum basale

What is the function of the Dermoepidermal junction?

Separates epidermis from dermis

What are the layers of the Dermoepidermal junction?

Cell membrane of basal keratinocyte, Hemidesmosomes, Lamina Lucida, Lamina Densa, Sublamina Densa

What are the components of the dermis?

Collagen, elastin, reticulin fibers; Glycosaminoglycans, mucin ground substance; fibrocytes, mast cells, macrophages cells; blood vessels, myelinated and non-myelinated nerves

What types of glands are epidermal appendages?

Sebaceous (holocrine, sebum secretion into hair follicle) and sweat (apocrine/epotrichial-merocrine for thermoregulation, eccrine/atrichial-merocrine on footpads) glands.

What are the functions of gland secretions in the skin?

Lubrication, water retention, pliability, bacteriostatic and fungistatic properties.

What are the phases of hair growth?

Anagen (growth), Catagen (intermediate), Telogen (resting).

How do hormones and deficiencies affect sebum secretion and hair growth?

Estrogen, glucocorticoids, and fatty acid deficiency decrease sebum and hair growth. Androgens increase sebum and hair growth. Progesterone can increase or decrease sebum and hair growth.

Why is an appropriate initial workup important in dermatology?

Decreases chances for chronic irreversible changes. Attention to detail. Consistent and practical initial approach.

How can staff be used wisely in a dermatology practice?

Receptionist collects history, technician does TPR and helps complete derm history, summarize findings, basic procedures with assistance, pharmacy items and instructions, initial phone call contact.

What historical information is important in dermatology cases?

Age of onset, sudden vs gradual, travel history, seasonal influence, body areas affected, initial presentation, itchiness, animal’s environment, contact animals/humans, related animals with skin problems, previous testing/results, previous treatment/results, flea control, diet, medical history, current medication.

What skin issues are commonly seen in young dogs?

Young dogs: ectodermal defects, puppy pyoderma, demodex, ringworm.

What breeds are predisposed to atopy?

Terriers, Labs, Golden Retrievers, Boxers, Setters.

What are the steps in a dermatological examination?

Complete a good general physical examination, examine skin and hair coat in systematic manner, examine mucous membranes, ventrum, interdigital spaces, nails, footpads, palpate lesions, inspect ear canals.

What are some primary skin lesions?

Macules, papules, pustules, plaques, vesicles, wheals, nodules, tumors.

What are some secondary skin lesions?

Crusts, epidermal collarettes, scars, ulcers, erosions, excoriation, lichenification, hyperpigmentation, comedones, hyperkeratosis, fissure, alopecia.

What are three broad categories of pruritus causes?

Infections, infestations, allergies.

What is included in the 'Minimum Data Base' for dermatologic issues?

Skin scraping, flea comb, ear swabs, Wood’s lamp, ringworm culture, surface cytology, cytology of exudate.

What should you evaluate during a therapeutic trial for a dermatologic condition?

Evaluate response to flea control, scabicidal therapy, antibiotics, steroids, topical therapy/bathing.

How is a skin scrape performed?

Clip hair, mineral oil on skin, use dull clean #10 scalpel blade, coverslip, 100x magnification

How should direct examination of hair and scale be performed?

Pluck hairs, arrange orderly, coverslip, examine ends and roots, examine for superficial fungi.

What stains are used for impression smears and aspirates?

Wright’s (cell morphology), Gram stain (pathogens), New methylene blue (wet mounts).

How do you perform a dermatophyte culture?

Select hairs at periphery of lesion, clip to within ¼ inch, prep with alcohol, pull hairs, inoculate on media, send to microbiology lab or check daily, perform macroconidia prep if media turns red.

What are the key dermatology MDB components?

Skin Scrapings, Cytology, Flea combing, Fungal Culture/Wood’s Lamp.

What anesthesia is needed for a skin biopsy?

For ears, face, mucous membranes, deep lesions – general anesthesia or heavy sedation. General skin – biopsy with local anesthesia, +/- mild sedation.

What considerations are important when performing a skin biopsy?

Choose a good primary lesion, choose many lesions in different phases, choose a good pathologist, give the pathologist as much information as possible.