Pathology: Dermatology 1 + 2 + 3 Flashcards

Question

What are the possible routes of entry that can cause Pyoderma?

Answer 1

- Follicular openings - Hematogenous spread - Direct entry through damaged skin

Answer 2

- Disorders of keratinization (seborrhea) - Endocrine disease - Chronic dermatitis: allergy vs parasite etc. - Immunodeficiency - Anatomic predisposition - Common in dogs, compared to cats: dogs have a thin stratum corneum, they lack the lipid seal of hair follicles and have a high skin pH

Answer 3

- This is a superficial pustular dermatitis - Caused by Staph intermedius, which releases exfoliative toxins that cause intra-epidermal splitting - Common in prepubescent and pubescent dogs - Associated with poor environmental hygiene or poor nutrition - If found in adults, look for an underlying immunosuppression

Answer 4

- This is skin fold pyoderma - Commonly seen in brachycephalic breeds: skin folds of the face create frictional trauma and trap moisture, this allows for opportunistic bacterial infections +/- Malassezia

Answer 5

- Moist, alopecia, slightly raised, red, well-circumscribed lesions leading to ulceration + crusting = very painful - Hot spots are very common in dogs, especially with long hair and dense undercoats, and more common in hot humid weather - Pathogenesis: self-trauma, leading to bacterial infection+/- underlying pruritus such as flea allergy dermatitis

Answer 6

- Proper name for Greasy Pig Disease = etiological agent is Staph hyicus, but can be due to other Staph infections - This is a collection of small papules and pustules, which starts at the head and can become generalized in 24-48 hours - Smells bad, greasy exudate and is usually non-pruritic - Predisposing factors = other skin lesions, poor nutrition/ husbandry, lacerations from biting or sharp edges in the environment, wrong temp or humidity - Histopathology = Subcorneal pustules, neutrophilic exocytosis (neutrophils moving up through the epidermis), spongiosis (edema in the epidermis), intracellular edema - Can be fatal in neonatal pigs

Answer 7

- aka Rain Rot/ Rain Scald - Etiological agent = dermatophilus congolensis, which is a gram + filamentous bacteria - Predisposing factors: wet weather in humid climates, leading to prolonged wetting of the skin/ hair/ wool, allowing penetration of the epidermis by zoospores - Histologically: pustule formation + bacteria

Answer 8

- An autoimmune disease involving antibody-mediated reactions against cell adhesion proteins (desmosomes) - Pemphigus foliaceous is the most common and mildest form of pemphigus, and is reported in dogs, cats, horses, and goats - Can be spontaneous, drug-induced or associated with allergic skin diseases - Usually affects the face, ears, footpads and clawbeds, which leads to a pustular dermatitis, involving vesicles, pustules, crusts, and ulcerative lesions - Histologically: will see eosinophilic pustular dermatitis with intralesional acantholytic keratinocytes and non-degenerative neutrophils

Answer 9

1) Pemphigus vulgaris 2) Bullous Pemphigoid 3) Epidermolysis bullosa

Answer 10

- Very severe autoimmune disease affecting the deep layers of the skin, of the whole body, in particular areas of trauma (e.g. claw folds, underarms, groin and mouth) - Will see deep ulcers, itchy skin and pain, fever, lethargy, depression, anorexia - Can develop into bacterial infections which are common and fatal

Answer 11

- The most severe of the pemphigus diseases | - Will see deep ulcers, itchy skin and pain, fever, lethargy, depression, anorexia

Answer 12

- This is a mechanobullous or autoimmune disease Mechanobullous/ Hereditary form = congenital malformation of collagen Acquired/ Autoimmune form = Antibodies are produced against the collagen - In children, they are called the Butterfly children - Reported in Humans, dogs, cats and cattle - Histologically: will see loss of epithelial integrity, blister formation and sloughing of skin

Answer 13

- Erythema multiforme + Toxic epidermal necrolysis - Superficial necrolytic dermatitis - Photosensitization - Herpesvirus - Cowpox virus - Burns

Answer 14

- Toxic epidermal necrolysis is a more severe form of Erythema multiforme - They are both uncommon type 4 hypersensitivities towards antigens on the keratinocyte surface, which induces apoptosis - Cause: believed to be antigenic mimicry following drug administration, an underlying infection, neoplasia, dyes/ preservatives in pet foods - Will see widespread coalescing erythematous macules (target lesions), leading to vesicle formation and ulcers in the trunk, axilla and groin

Answer 15

- Skin disease associated with liver disease = Hepatocutaneous syndrome. In cats, it can be associated with neoplasias in the liver or pancreas - Pathogenesis: liver disease leads to issues with the metabolism of proteins, these proteins are needed for collagen in the skin

Answer 16

UV light is absorbed by photodynamic chemicals in the skin, leading to free radical damage, and epidermal necrosis of lightly pigmented or sparsely haired skin Type I (primary): ingested photodynamic substances, such as plants with photoreactive pigments, or mycotoxins, molds, chemicals and rugs (quinolones and griseofulvin) Type II (intrinsic): endogenous pigment accumulation due to a defective porphyrin metabolism Type III (Hepatogenous): abnormal build up of phylloerythrin due to liver disease or biliary obstruction (common in severe forms of liver fluke) - Histopathology (regardless of type): coagulative necrosis of epidermis, dermal edema, fibrinoid degeneration of vessel walls and thrombosis

Answer 17

- Bovine herpesvirus 2 (cattle): causes bovine ulcerative mammillitis, and pseudo-lumpy skin disease - Bovine herpesvirus 4 (cattle): causes bovine herpes mammary pustular dermatitis - Feline herpesvirus 1 (cats): feline facial dermatitis and stomatitis - Feline Cowpox virus (cats) - Ovine herpesvirus 2 (cattle): malignant catarrhal fever

Answer 18

- Ulcerative mammillitis: this is a self-limiting disease that affects the udder and teats - Pseudo-lumpy skin disease (PLSD): this is a generalized superficial skin disease, that leads to cutaneous nodules and plaques with central depressions (due to necrosis)

Answer 19

- Malignant catarrhal fever These animals usually present with fever, depression, ocular and nasal discharge, lesions of the buccal cavity and muzzle, swelling of lymph nodes, an opacity of the corneas, inappetence and diarrhea Some animals, when the disease goes systemic and to the brain tissue, it can cause neurological signs like ataxia, nystagmus and head pressing

Answer 20

- Feline herpesvirus ulcerative dermatosis Leading to upper respiratory tract disease such as rhinotracheitis and conjunctivitis Can get erosions and ulceration of the face (muzzle, periorbital regions and planum nasale) Histologically: Severe necrosis and ulceration of the epidermis and dermis, massive exudation to form large superﬁcial crusts, mixed dermal inflammation with numerous eosinophils, large amphophilic intranuclear inclusion bodies in the epithelium

Answer 21

- Ulcerating, red, crusted macules of the head, neck or forelegs. Believed to be from the bites of rodents, hence the areas that it appears - Is zoonotic - Histology: severe ulceration, serocellular crusting, ballooning degeneration of keratinocytes (epidermis and hair follicles) - numerous, large intracytoplasmic, brightly eosinophilic inclusions

Answer 22

- Acute severe UV light exposure leading to a sunburn - Gross: red, blistering/ vesicles and the sloughing of necrotic skin - Pathogenesis: direct cellular injury by ionizing radiation, leading to endothelial damage and cytokine production

Answer 23

- Chronic hyperplastic dermatosis - Acral lick dermatitis - Malassezia dermatitis - Pox virus/ parapox virus

Answer 24

This is a self-inducing traumatic skin lesion, usually of the dorsal distal extremity - Cause: strong psychogenic component (boredom), but must rule out allergy, bacterial or fungal disease, demodicosis, previous trauma and underlying joint disease - Gross: alopecic, firm and oval plaque - Histology: compact hyperkeratosis, severe irregular acanthosis (epidermal hyperplasia) +/- erosion or focal to extensive ulceration with exudation, inflammatory cells perivascular, perifollicular, or diffuse and often perihidradenitis +/- deep folliculitis and furunculosis

Answer 25

- Very common in dogs - etiological agent: Malassezia pachydermatis, often secondary to another underlying disease (rarely it is a primary event, unless the dog has a hypersensitivity to Malassezia) - Leads to excessive sebum production, moisture accumulation and disruption of normal barrier function - Gross: Focal, multifocal, or generalized; ventral neck, ventral abdomen, axillae, face, pinnae, feet, forelegs, and skin folds: erythema, greasy or waxy adherent scales and crusts, hair loss, hyperpigmentation, licheniﬁcation, ‘musty’ odour.

Answer 26

- Bovine Papular Stomatitis - Orf (Contagious Ecthyma) - Parapox of red deer - Pseudocowpox - Sealpox

Answer 27

- Parapox virus infection in sheep - Causes vesicular formation on the mucous membranes and teats of ewes - Is painful, common, contagious, zoonotic,

Answer 28

- Seborrhea (Seborrhea dermatitis, ear margin seborrhea) - Sebaceous adenitis - Nasodigital hyperkeratosis - Ichthyosis - Callus - Zinc responsive dermatosis

Answer 29

- This is a non-specific name for excessive scaling, crusting and greasiness - Primary vs Secondary causes - - Secondary: due to underlying endocrinopathies or allergies, and is commonly associated with superficial pyoderma, Malassezia infections and alopecia -- Primary: Idiopathic or inherited cause. WHWT, Cocker Spaniels and Labs are most commonly affected Primary Idiopathic Seborrhea: - - Pathogenesis: thought to involve hyperproliferation of the epidermis, hair follicle infundibulum and sebaceous glands - - Histology: marked epidermal and follicular hyperkeratosis + comedones Primary Inheritied Seborrhea: -- Pathogenesis: Inherited faulty keratinization, will see at a young age

Answer 30

- Commonly seen, affects the margins of the ears. Dachshunds are overrepresented - Cause: thought to be due to abnormality in cornification - Will see adherent keratinous deposits on both the lateral and medial margins of the pinna

Answer 31

- This is a heritable autoimmune disease of Standard Poodles and Akitas, that causes inflammation and loss of sebaceous glands - Leads to scaling and poor quality coat

Answer 32

- This is an idiopathic, non-inflammatory disease of the planum nasale and pawpads - Doesn't cause any real problems to the animal, more so aesthetically a problem

Answer 33

This is an inherited disease, where the animal is born with thickened and marked scaling of the skin (look like fish scales)

Answer 34

This is a pressure point granuloma, commonly found on bony prominences or pressure points of giant or large breed dogs

Answer 35

- This is due to a dietary deficiency in Zinc, or excess zinc-chelators (calcium, iron or phytates) - Pigs: usually present at 2-4 months, and show anorexia and reduced growth rates - Ruminants: several in a herd will be affected, and show anorexia, weight loss, decreased milk production, depression and diarrhea - Dogs: - - Syndrome 1: Siberian huskies, Alaskan malamutes <1 year of age - - Syndrome 2: puppies of any breed

Answer 36

- Perivascular and vascular dermatitis - Lichenoid dermatitis - Nodular/diffuse dermatitis - Degenerative, Dysplastic and Depositional Diseases

Answer 37

- Contains MANY diseases, but histologically it is non-specific Perivascular dermatitis tends to be Hypersensitivity/ allergy or Parasitic related: resulting in inflammatory cells around vessels of the dermis +/- hyperplasia of the epidermis Vascular Dermatitis tends to be more severe in nature

Answer 38

- Atopic dermatitis - Food allergy - Allergic contact dermatitis - Insect bite hypersensitivity - Feline allergic miliary dermatitis - Flea allergy dermatitis - Urticarial allergic eruptions (Urticaria or Hives)

Answer 39

- Canine sarcoptic acariasis - Feline notoedric acariasis - Psoroptic mange - Chorioptic mange - Cheyletiellosis

Answer 40

- Septic vasculitis - Immune-mediated vasculitis - Infarctions - Frostbite

Answer 41

- Atopy is the tendency to produce an exaggerated IgE immune response (type I hypersensitivity) and degranulation of mast cells to otherwise harmless environmental substances - While an allergic disease can be defined as the clinical manifestation of this inappropriate IgE immune response It is believed to be an inherited trait, although contact with the allergen or irritant must occur before the hypersensitivity reaction can develop - Potential allergens include: house dust mite proteins, plant pollen, mold spores etc.

Answer 42

The patient must have 3 of the 5 following: 1) Corticosteroid-sensitive pruritus 2) Erythema of the pinnae 3) Bilateral cranial erythematous pododermatitis 4) Cheilitis (inflammation of the lips) 5) Appearance of first signs between the ages of 6months and 3 years of age Diagnosis of atopy is based on clinical signs, physical exam, intradermal skin testing, and the use of RAST (radioallergosorbent test) and the ELISA for elevated allergen-specific IgE

Answer 43

- Clinical signs include PRURITIS: of the face, paws, distal extremities, ventral abdomen - - Skin lesions are due to self-trauma, secondary bacterial pyoderma, Malassezia dermatitis and secondary seborrhea - Gross: Alopecia, salivary staining of hair excoriations, papules, pustules, crusts, hyperpigmentation, lichenification, pyotraumatic dermatitis - Histology: Perivascular infiltrate of macrophages, lymphocytes, mast cells, few eosinophils and neutrophils Epidermis: erosions, hyperplasia, exocytosis of lymphocytes, eosinophils, subcorneal pustules

Answer 44

Location of the lesions! - Flea Allergy Dermatitis: dorsal lumbosacral area, groin and caudal thighs - Food allergy: the head and distal extremities - Allergic contact dermatitis: glabrous, exposed areas such the muzzle, groin, axillae, ventral interdigital webs and perineum. - Insect bite: Face, nose, eyes (mane and tail)

Answer 45

- You get mast cell degranulation in response to IgE production - Histopathology: Dermal edema, mast cell degranulation, eosinophilic infiltration, capillary dilation

Answer 46

Parasite: Sarcoptes scabiei or Notoedres cati in cats Dogs are affected at the ears, elbows, extend to ventral abdomen, face and legs Complete life cycles in tunnels burrowed into and under stratum corneum = VERY ITCHY +/- Allergic reaction: Acute/chronic perivascular dermatitis typical for allergic disease and continued scratching

Answer 47

Parasite: Psoroptes spp - Affects sheep (sheep scab) in the scrotum, testis, ears, inguinal and perianal folds - Affects cattle at the poll, ithers, base of tail - Affects horses in their ears - Affects Rabbits in their ears - Affects goats in their ears - Causes intense prurutis, leading to marked decrease in weight gain + reduced milk production - Histology: Superficial perivascular dermatitis with eosinophils, mast cells, lymphocytes, spongiosis, exudative, hyperplastic

Answer 48

Parasite: Chorioptes spp -- Most severe in winter, causing itching, erythema, alopecia, lichenification, wrinkling of skin - Affects cattle: perineum, tail, scrotum, udder and hindlimbs - Affects horses: lower limb and fetlock - Affects sheep: distal extremities

Answer 49

Parasite: Cheyletiella mite -- A zoonotic mite, causing mild itch - Affects dogs: mainly truncal scaling and mild crusting, lesions may be generalized in chronic cases. Itchiness is usually mild or absent - Affects cats: mild scaling and crusting, dorsal trunk but may be generalized, can see alopecia and poor haircoat. Itchiness is usually mild to absent

Answer 50

- This is a rare secondary bacterial infection to sepsis - Caused by a severe deep pyoderma or a defect in the host immune response - Associated with bacterial endocarditis, with the release of septic emboli - Gross: Swelling, erythema, purpura, erythematous plaques, haemorrhagic bullae, necrosis, and ulceration: it can be generalized or localized (less extensive collateral circulation such as the distal extremities and pinnae) Septic vasculitis always is life-threatening; can go into coma and death as possible sequelae. - Histology: neutrophils traveling through the walls, and causing damage to the vessel wall, leading to fibrinosuppurative or hemorrhagic exudation, vascular necrosis + fibrin thrombi, and leading to severe hemorrhage, edema and dermal necrosis

Answer 51

- Reddened areas (hyperaemia/hemorrhage) - Edema development - Lesions follow a linear pattern and geometrical shapes (mapping to vascular supply) - Vascular lesions resulting in ischemia → then see features of degeneration/necrosis - Lesions can become inflamed secondarily to bacterial infections e. g. Purpura hemorrhagic - - Type III hypersensitivity, creation of antibodies that attack the proteins in endothelial cells (because they are similar to Strep. equi proteins)

Answer 52

- Gross: Sharply demarcated geometrical shaped dark red to blue areas - - Chronic: firm, dry, sunken, darkened (necrosis predominates over haemorrhage) ``` Causes: - Vasculitis due to Erysipelothrix rhusiopathiae Gram negative septicemias - Salmonella, Pasteurella, E. coli Spider/snake bite Drug reaction Secondary to ulceration ``` - Frost bite - Toxins causing extreme vasoconstriction (ergot)

Answer 53

- Cause: exposure to cold temperatures - Pathogenesis: Formation of ice crystals which physically disrupt cells Vasoconstriction and endothelial damage →reduced blood flow →thrombosis →infarction

Answer 54

- Dense superﬁcial band-like or laminar dermal inﬂammation that is between the dermal-epidermal junction = interface dermatitis Examples: - Mucocutaneous pyoderma - Discoid lupus erythematosus - Systemic lupus erythematosus Histologically these diseases are difficult to differentiate and clinical correlation and response to treatment may be required for diagnosis.

Answer 55

- Gross: Erythema, swelling, and adherent crusts around mucocutaneous junctions - Depigmentation of the lips - Pruritus is mild to moderate, and pain may be present - The pathogenesis is not understood. (bacterial infection maybe) - complex immunologic pathogenesis Histology: Epidermal hyperplasia + exocytosis + spongiosis Basal cell apoptosis, erosions, ulceration Neutrophilic crusting Dermis – perivascular to lichenoid infiltrates – predominantly plasma cells Pigmentary incontinence (pigment present in the macrophages of the dermis)

Answer 56

- Autoimmune disease: Systemic Form vs Localized (Discoid) Form -- Systemic form (dogs, cats, horse) T-cell imbalances, altered immune regulation B-cell hyperactivity, production of auto-antibodies against a variety of membrane and soluble antigens (antinuclear antibodies) Type III hypersensitivity reaction; Antibody-antigen complexes under basement membrane zone and in dermal vessel walls UV light exacerbates Breeds: Collies, German shepherds, Persian, Siamese cats 1/3 cases skin affected. Also polyarthritis, pyrexia, anaemia, glomerulonephritis Mucocutaneous, ulcerative dermatitis on face, ears, nose, lips -- Discoid form (dogs) Photosensitive nasal dermatitis Nasal planum, perioral, periocular, pinnal skin Collies, German shepherds Gross: erythema, depigmentation, scaling crusting alopecia Histology: Lichenoid/interface dermatitis with basal cell apoptosis

Answer 57

- Actinomycosis - Mycobacteriosis - Acral lick dermatitis - Pseudomycetoma - Besnoitia and leishmania - Juvenile sterile granulomatous dermatitis and lymphadenitis - Foreign body reactions - Eosinophilic granuloma complex (feline and equine)

Answer 58

Pyogranulomatous osteomyelitis (lumpy jaw) Can cause pyogranulomatous dermatitis (mycetoma) Gram-positive bacterium Actinomyces bovis Primarily cattle but can affect other species Damage to the skin – crush, feeders etc Gross: large nodular often ulcerated lesions Histology: nodular to diffuse pyogranulomatous dermatitis with bacterial colonies surrounded by club-shaped brightly eosinophilic Splendore-Hoeppli material

Answer 59

Cats and dogs (cats more commonly affected) Granulomatous mycobacterial skin diseases Acid fast bacteria – hard to culture – PCR Feline leprosy - Mycobacterium lepraemurium Transmission unknown – biting insects? FIV/debilitation may be predisposing factors Numbers of mycobacteria in lesions can be low – might not see on histo

Answer 60

- aka Juvenile cellulitis, juvenile pyoderma, puppy strangles - Puppies (3 weeks to 6 months) - Dramatic response to immunosuppressive dosages of glucocorticoids →underlying immune dysfunction possible - Gross: acute swelling of the face, especially affecting the eyelids, lips, and muzzle. Lymphadenopathy. Bilaterally symmetric erythema, papules, nodules, and transient pustules and vesicles, usually within 24 hours. +/- Secondary bacterial infections - Histology: granulomatous to pyogranulomatous inflammation within the dermis – nodules May extend to the panniculus and subcutis

Answer 61

- Not a disease, a pattern of lesions. - Tend to be pruritic Several pathologies under one complex: 1) Indolent ulcer – ulcers on upper lips. 2) Eosinophilic plaque – discrete red to ulcerated plaques on the abdomen or medial thighs. 3) Eosinophilic granuloma – nodules (may be ulcerated) on thighs, face or mouth. - Commonly seen in cats with allergic skin disease. - Hypersensitivity pathogenesis suggested as they respond well to steroid treatment - Histology: Eosinophilic infiltration in dermis. Epidermal hyperplasia, spongiosis

Answer 62

- Common nodular skin disease. - Single/multiple, firm circumscribed nodules. - Commonly on the Neck back and withers. Idiopathic. - Non-problematic unless they are around the areas of the saddle, where rubbing can be painful Affects all ages breeds and both sexes. Eosinophilic granuloma with central area of necrotic collagen and calcification

Answer 63

- Calcinosis cutis - Calcinosis circumscripta - Ehlers Danlos syndrome - Feline acquired skin fragility

Answer 64

- This is an inappropriate mineral deposition in the dermis, epidermis, or subcutis. - Commonly due to iatrogenic hyper-glucocorticism or Cushing's Disease - Gross: Chalky, white-to-pink material with a feathery or blurry margin Firm, gritty yellowish-tan to dark red plaques evolve from coalescing erythematous papules. Ulceration and crusting occur as gritty mineral salts are extruded from older lesions (resemble sand) -Most common in the ﬂexural surfaces of the groin, back of the neck, and axillae. - Histology: Dystrophic mineralization of dermal collagen accompanied by granulomatous inflammation Occasionally osseous formation too

Answer 65

- A clinically distinctive subgroup of calcinosis cutis, with focal deposition of mineral salts in tumour-like nodules, usually in the subcutaneous tissue - Causes include: Idiopathic or dystrophic Site predilection is prognostically important Tongue, ears (post cropping), bony prominences, injection sites, paws - In the paw pads, it usually indicates renal failure, especially if multiple paws are affected Histology: granulomas centred on lakes of mineral – dermis and subcutis

Answer 66

- Cutaneous asthenia, dermatosparaxis - A Genetically and biochemically diverse disorder that encompasses multiple heritable, congenital defects of dermal connective tissue. - Histology: Collagen bundles irregular and haphazard arrangement

Answer 67

- Rare syndrome of multifactorial etiology - Skin is markedly fragile and thin skin, but without evidence of hyperextensibility - Minimal trauma leads to extensive tearing and shedding of the affected skin - Associated with iatrogenic and naturally occurring hyper-glucocorticism, diabetes mellitis, or the excessive progestational compounds - Less commonly associated with systemic diseases of the liver, kidney - Histology: Epidermal and dermal atrophy

Answer 68

- Pustular and Nodular Diseases without Adnexal Destruction - Pustular and Nodular Diseases with Adnexal Destruction - Atrophic Diseases of the Adnexa - Diseases of the Panniculus

Answer 69

- Superﬁcial bacterial folliculitis | - Dermatophytosis

Answer 70

- Common in Dogs and cats - Etiological agent: Staphylococcus pseudointermedius - Usually secondary to coexistent disease or other predisposing factors +/- immunosuppression - Gross: follicular pustules →crusted papules. Alopecia, hyperpigmentation Inguinal and axilla, interdigital webs - Histology: Pustules within the infundibulum (folliculitis)

Answer 71

- Superficial cutaneous, self-limiting - Caused by: Microsporum or Trichophyton Common calves, horses, cats Young animals or immunosuppressed - Fungi colonize keratin, do not need to invade tissue - Predisposing factors: Hot/humid environments - Zoonotic! Gross: Expanding circular patches of scaling and alopecia or stubbled hair Biopsy; to be taken within the expanding border - Fungal stains may be necessary PAS, Grocott Histology: Neutrophilic luminal folliculitis +/- Furunculosis (hair follicle rupture)

Answer 72

Deep bacterial folliculitis and furunculosis: - Post-grooming furunculosis - Acral lick dermatitis - Interdigital furunculosis - Callus pyoderma - Canine acne Feline acne Canine demodicosis Sebaceous adenitis

Answer 73

Common – dogs and cats Traumatic furunculosis include acral lick dermatitis, interdigital furunculosis, callus pyoderma, post-grooming furunculosis, and canine acne Self inflicted – licking, rubbing, conformational, repeated trauma, severe back combing, back clipping or aggressive bathing Furunculosis: traumatically released hair fragments and remnants of follicular keratin – foreign body reaction Staphylococcus pseudointermedius, Proteus sp., Pseudomonas sp., and Escherichia coli Predisposing factors: Generalized demodicosis, hyperadrenocorticism, widespread actinic disease and immunologic defects Gross: Pustules, nodules, fistulas, haemorrhagic crusts, erosions, ulcers, alopecia, hyperpigmentation and licheniﬁcation Dogs – haemorrhagic bullae Pain and pruritus - self trauma Histology: +/- ulceration, neutrophils within hair follicles, follicle rupture, pyogranulomatous inflammation around keratin and hair shaft fragments within the dermis

Answer 74

Relatively common Comedone formation and secondary inﬂammation on the chin and skin adjacent to the lips - Not associated with young age. Poor grooming habits and defects in follicular keratinization Staphylococcus spp., Streptococcus spp., and Pasteurella multocida - Histology: comedones, rupture, furuncluosis, granulomatous

Answer 75

Noncontagious Overpopulation of demodex species Juvenile-onset and adult-onset forms Localized (self limiting) or generalized (life threatening) Familial - young dogs CMI defect Adult-onset – often associated with systemic disease such as neoplasia, endocrinopathy, or immunosuppressive therapy

Answer 76

- Hypothyroidism - Hyperglucocorticoidism - Hyperestrogenism - Post clipping alopecia - Feline psychogenic alopecia

Answer 77

- This is a non-inflammatory disease of the hair follicle - Typically associated with endocrinopathies: Hypothyroidism, Hyperglucocorticoidism and Hyperestrogenism Signs include: Bilateral symmetric alopecia Hyperpigmentation Hair coat dry brittle, dull, easily epilated Secondary pyoderma and seborrhoea are common

Answer 78

- Ortho-/ parakeratotic hyperkeratosis - Follicular keratosis - Decreased number of hair shafts in follicular infundibular - Mainly telogen hairs and follicular atrophy - Epidermal hypermelanosis - Dermal and sebaceous gland atrophy

Answer 79

- This is a lack of hair regrowth following close clipping to the skin. - More common in plush coated breeds Siberian Husky, Alaskan Malamute, Samoyed, American Eskimo, Chow Chow, Keeshond, and Pomeranian Cause unknown – think change in thermoregulation locally Haircoat may not return for as long as 6 to 12 months after clipping New coat may be darker Histology: hairs in telogen phase (arrest stage)

Answer 80

- This is a self-traumatic hair removal - Associated with Obsessive/compulsive disorder or anxiety disorders - Diagnosis of exclusion - Well-demarcated, partial or almost complete alopecia over the lateral trunk, caudal and medial thighs, abdomen, and dorsal forelegs - Faeces – hair in excess - Histology: normal skin +/- mild inflammation

Answer 81

- Vaccine-associated panniculitis - Traumatic panniculitis - Idiopathic sterile nodular panniculitis - Feline pansteatitis (rare) (vit E deficiency): most commonly reported cause is due to the feeding of red tuna as an exclusive diet or excessive cod liver oil supplementation - Pancreatic panniculitis (rare)

Answer 82

- Commonly have a multifactorial etiology - Major focus of inﬂammation is in the fat of the subcutis - -> Lipocytes, ﬁbrous trabeculae or septa, and blood vessels - -> Becomes a vicious circle, as inflammation of the lipocytes causes lipid release, which are pro-inflammatory, attract inflammatory cells and more lipocytes are damaged - Localized panniculitis is commonly initiated by local trauma or injection of foreign material: doesn't have to be infectious - Generalized or multifocal panniculitis reﬂects metabolic or systemic disease; or remain idiopathic

Answer 83

- Post-rabies – relatively common - -> can happen with any injection of any substance e.g. long-acting antibiotics - Gross: Focal alopecia – minimal gross inflammation, 2-3 months post vaccine Cause: Unusual idiosyncratic immunological reaction to rabies antigen targeting blood vessels - Long-haired or curly-haired dogs overrepresented - Revaccination not recommended when this does happen - Histology: Ischemic lesions of the dermis (pale and atrophy). Accumulations of lymphocytes, fewer histiocytes, and occasional plasma cells - lower dermis and panniculus - surround vessels +/- amorphous basophilic foreign material

Answer 84

- Focal ischemia caused by blunt trauma, chronic pressure, leading to a decreased blood supply - More common in obese cats and dogs - Gross: focal, ﬁrm subcutaneous nodule. Lesions are seen predominantly on the trunk, especially dorsally over the dorsal spinous processes, and over the sternum ventrally - -> Lesions are asymptomatic - Histology: large central focus of lobular fat necrosis. Ruptured adipocytes form large, cystic spaces. Foamy macrophages containing lipid debris. +/- hemorrhage or hemosiderosis. Marginal ﬁbrosis.

Answer 85

- This is a canine syndrome - Affects the nails, where separation of the claw from the clawbed, sloughing of claws. Regrowth of misshapen, dry, brittle, short claws. Usually, all claws, all feet are affected. - Cause: Idiopathic, but adverse reaction to food and drug administration - Large breed dogs predisposed. - Histology: Interface (lichenoid) inﬂammation obscuring the junction between clawbed epithelium and adjacent dermis. Apoptosis and vacuolation of basal cells. Pigmentary incontinence.

Answer 86

``` - Epithelial neoplasms: Epidermis Hair follicles Sebaceous gland Apocrine glands Nail bed ``` - Round cell: Histiocytic Mast cell Lymphocytic (lymphocytes and plasma cells) ``` - Mesenchymal neoplasms Fibrous Vascular Perivascular Lipocyte Muscle Neural Melanocytic Sarcoid ```

Answer 87

- Non-neoplastic or benign tumors: Dermoid cyst Papillomas - Malignant: Squamous cell carcinoma Basal cell carcinoma

Answer 88

- Occurs more in Dogs than cats - Cause: Developmental anomalies: focal reduplication of the entire skin structure, including dermis and adnexa Midline, solitary, dermal or subcutaneous nodule Small pore/ entry +/- hair - Occasionally extend into the spinal canal - Rhodesian Ridgeback are predisposed (can have single or multiple dermoid cysts)

Answer 89

- Caused by papilloma virus - 2 types of papillomas: Squamous and Fibropapilloma Common in cattle, horses and dogs - Pathogenesis: viral genes inactivate host tumor-suppressor proteins - Benign, spontaneously regress, rarely progress to SCC - Gross: horny cauliflower-like masses - Histology: hyperplastic epidermis, supported by a thin dermal stalk with dilated capillaries. Marked expansion of the stratum spinosum and ballooning degeneration. Eosinophilic cytoplasmic inclusion that represents aggregates of keratin +/- viral inclusion bodies

Answer 90

Common in cow, dog, cat, horse Sites; often lack pigment, sparse hair - Horse, cattle; eyelid, penis - Cat; pinna, planum nasale, eyelids - Dog; head, abdomen, limbs and digits Carcinogenic factors; sunlight – UVB – free radicals papilloma virus – not consistently identified genetics

Answer 91

- Benign: Nodular sebaceous hyperplasia - Benign: Sebaceous/ Meibomian adenoma / epithelioma - Malignant: Sebaceous carcinoma - Benign to Malignant: Perianal gland tumours – adenoma/ epithelioma/carcinoma

Answer 92

- These are common - Dogs > cats, older animals Gross: yellow-white, alopecic, ﬁrm, and dome-shaped or papillated nodules that are less that 5mm in diameter (pigmented Meibomian glands) Histology: multiple, enlarged, but otherwise normal sebaceous lobules clustered around one or more dilated sebaceous ducts and hair follicles → hyperplasia No orientation around ducts or follicles → adenoma Epithelioma: increased basal reserve cells, increased recurrence, very rare metastasis

Answer 93

- This is a nodular hyperplasia similar to sebaceous hyperplasia - Associated with androgens, and thus can see regression with castration (increase incidence in Entire Males) - Gross: Hyperplasia and adenoma – mm to 10cm +/- ulceration, rubbery, tan. - Histology: multiple enlarged lobules of well-differentiated hepatoid cells with a single peripheral layer of basaloid reserve cells - Perianal Carcinomas are rare, they tend to be more infiltrative, and metastasis is rare