Dermatology Flashcards
Blastomyces dermatitidis
Blastomycosis- systemic fungal disease the primarily affects dogs, humans, and cats. It is a dimorphic fungus found in Mississippi, Missouri, and Ohio River valley, and mid-Atlantic states and Canada (Quebec, Manitoba, and Ontario). Infection occurs primarily through inhalation. This is a systemic infection that can cause damage to any organ or system including the central nervous system but the most common clinical signs and physical exam findings include: Depression, anorexia, weight loss, fever, lameness, lymphadenopathy, harsh lunch sounds, draining skin lesions, chorioretinitis, uveitis, and cough.
Definitive diagnosis depends on identification of the organism: round to ovoid yeast measuring 8-25 um. It is pale pink when stained with H & E with a refractile, double-contoured wall. They have single broad-based buds. Treat with systemic antifungal therapy, usually itraconazole.
Bullae
large blister containing serous fluid
Cheyletiella
“walking dandruff” genus of mites that live on the skin surface of dogs, cats, and rabbits
Collagenolytic granuloma (aka eosinophilic or linear granuloma)
usually occurs on the nose, chin, oral cavity, or caudal thighs. The lesions are typically raised and ulcerative or nodular.
Collarette
Characterized by a rim of peeling edges and a circular shape. Remnants fo previous primary lesions (vesicle, ballae, pustule, papule). The onset can be sudden and distribution may be widespread. Lesions are often superficial spreading pyoderma but may also be seen with some immune-mediated skin disease.
Cutaneous lupus
immune-mediated skin diseases in dogs
Cutaneous lymphoma
a disease of older dogs and cats with the most common breeds seen in our practice being Boxers and Golden Retrievers (see Photo 2). Cutaneous lymphoma can be epitheliotropic (usually T lymphocyte in origin in the dog) or non-epitheliotropic (usually B lymphocyte in origin). Sometimes referred to as mycosis fungoides, cutaneous lymphoma can have four presentations-exfoliative (see Photo 4, p. 5S) (the patient presents with erythema and a “peeling” of the skin sometimes resulting in large flakes), plaque (see Photo 5, p. 5S) (presents as nonraised, sometimes spherical shaped inflamed lesions), tumor stage (see Photos 6, 7, p. 5S) (usually varying sizes of erythemic raised, almost plateau-like lesions) and mucocutaneous ulceration/erythema.
Demodex
genus of tiny commensal mites that live in or near hair follicles of mammals
Dermatophytosis is caused by ____ and diagnosed with ____. Treatment includes:
infection of the hair, skin, or nails caused by a dermatophyte; Trichophyton, Microsporum or Epidermophyton genera. Dx with skin scraping/trichogram and identification of macroconidia. Treat with whole body therapy twice weekly (leave on lime-sulfur or eniconazole, or shampoo miconazole/chlorhex) and adjuvant local therapy (terbinafine, miconazole, ketoconazole), AND systemic antifungal therapy (itraconazole)
Eosinophilic plaques
Occur most frequently on the abdomen and medial thighs but can appear other places. They appear as single or multiple, raised, red, often ulcerated lesions of varying size (0.5-7 cm). They frequently have a cobblestone appearance and unlike eosinophilic ulcers, these are often pruritic. This condition is histopathologically similar to miliary dermatitis and is usually associated with underlying allergy.
Eosinophilic ulcer (aka indolent ulcer)
Typically occurs on the upper lip and may be unilateral or bilateral. They often have a characteristic central area of yellow to pink tissue with a slightly raised circumferential edge.
Folliculitis
Inflammation or an infection of the hair follicle
Furunculosis
Deep folliculitis resulting in a swollen, painful skin lesion
Macule
Change in surface color, without elevation or depression
Microsporum canis
Ringworm of domestic cats, also 70% of canine infections
Zoonotic. About 50% of strains fluoresce with ultraviolet light (Wood’s lamp). M. canis and M. gypseum can both present with white colony growth with a pH change at 5 to 7 days, but require different management strategies. Ultimate source of M. canis is a potentially asymptomatic cat.
Microsporum gypseum
Ringworm
Soil inhabitant - infects animals that are exposed during digging or rooting
Zoonotic
20% of canine infections
M. canis and M. gypseum can both present with white colony growth with a pH change at 5 to 7 days, but require different management strategies.
Microsporum nanum
Ringworm of pigs
Zoonotic
Mucocutaneous pyoderma
a common condition that may affect the nasal planum of dogs
Otodectes
surface mites. They are the cause of otodectic otitis, the most common mange of dogs and cats in the world. They are also found in the fox and the ferret. The mites inhabit the inner ear and feed on ear debris, they appear white in colour.
Pruritus is caused by irritation and the saliva of the mites, which is immunogenic. Secondary bacterial infection is common, resulting in purulent otitis externa which will require more treatment.
In cats, another presentation can be seen, which is that of an ectopic infection where signs are seen on other body parts such as the tail. This is due to contact e.g. cats sleeping in a curled position would allow mites to infest that area. Transmission of the mites can occur to kittens whilst they are suckling.
Papule
Circumscribed, solid elevations of skin with no visible fluid
Pemphigus foliaceus
generally a benign variety of pemphigus. It is an autoimmune skin disorder characterized by the loss of intercellular adhesion of keratinocytes in the upper parts of the epidermis (acantholysis), resulting in the formation of superficial blisters.
Pustule
small blister or pimple on the skin containing pus
Pyoderma
Term fo inflammation/infection of the skin and is often used to specifically imply bacterial skin infection, not a specific lesion.
Sarcoptes scabiei var suis
Scabies, sarcoptic mange. Main cause of mange in pigs. S scabiei var suis is highly contagious and zoonotic, though the pig is the definitive host. This parasitic mite burrows into skin causing intense pruritus and skin lesions. Tx involves avermectins at 2 week intervals for the pig. The people should go to the human doctor.
