Untitled Flashcards Set

Deep Pyoderma

• Prevalence: Common in dogs, especially short-coated breeds (e.g., German Shepherds).

• Risk Factors:

  • Allergic skin disease.

  • Trauma (e.g., grooming injuries, calluses on bony prominences).

  • Poor hygiene, overweight animals, or inappropriate bedding.

  • More severe in dogs with immunosuppression or chronic allergies.

Blastomycosis

• Geographic Distribution:

  • Mississippi, Ohio, and St. Lawrence River valleys.

  • Midwest (e.g., near beaver dams, decaying wood).

• Risk Factors:

  • Hunting or sporting dogs.

  • More common in young, outdoor dogs exposed to waterways.

Sporotrichosis

• Geographic Distribution:

  • Worldwide, but common in Michigan, Brazil, and temperate areas.

• Risk Factors:

  • Cats > Dogs or horses.

  • Exposure to puncture wounds (e.g., rose thorns, plant material).

  • Zoonotic risk is significant, especially from infected cats.

Cryptococcosis

• Geographic Distribution:

  • West Coast of the USA (associated with pigeon feces and Eucalyptus trees).

  • Worldwide prevalence in urban and rural areas.

• Risk Factors:

  • Cats > Dogs.

  • Immunocompromised animals are more susceptible.

  • Inhalation of spores from contaminated environments.

Atypical Mycobacterium Infection

• Geographic Distribution:

  • Worldwide but more common in tropical/subtropical climates (e.g., Brazil).

• Risk Factors:

  • Cats > Dogs.

  • Obesity increases susceptibility due to preference for fat tissue.

  • Puncture wounds, particularly cat bites.

Sterile Nodular Panniculitis

• Geographic Distribution:

  • No specific geographic association.

  • Rare in cats; more common in dogs.

• Risk Factors:

  • Possible triggers include vaccines, trauma, or drug reactions.

  • Predisposed breeds: Dachshunds, Miniature Schnauzers, and other small breeds.

Reactive Histiocytosis

• Geographic Distribution:

  • Seen worldwide but not common.

• Risk Factors:

  • More common in young to middle-aged dogs.

  • Breeds predisposed include Bernese Mountain Dogs, Collies, and Shetland Sheepdogs.

Plasma Cell Pododermatitis

• Geographic Distribution:

  • No specific geographic association.

  • More common in cats than dogs.

• Risk Factors:

  • May be associated with immune dysregulation or allergic conditions.

Interdigital Furunculosis

• Geographic Distribution:

  • No specific geographic association.

  • Common in dogs, especially large breeds with short coats (e.g., Bulldogs, Boxers, Labradors).

• Risk Factors:

  • Abnormal weight bearing, rough terrain, or inappropriate bedding.

  • Underlying allergies or conformational predispositions.

Neoplastic Nodules

• Geographic Distribution:

  • Depends on tumor type; many are seen worldwide.

• Risk Factors:

  • Older animals are more predisposed.

  • Genetic predispositions for certain tumors (e.g., Mast cell tumors in Boxers).

Lipoma

• Very common in older dogs, particularly large and overweight breeds.

• Rarely seen in cats.

• No breed or sex predisposition.

Intermuscular Lipoma

• Occurs most commonly in older dogs.

• No strong breed or sex predisposition.

Infiltrative Lipoma

• Rare but locally aggressive variant of lipoma.

• Occurs in dogs; incidence in cats is extremely low.

• No breed or sex predisposition.

Soft Tissue Sarcoma (STS)

• Accounts for 15% of all cutaneous and subcutaneous neoplasms in dogs.

• Typically affects middle-aged to older animals.

• May be more aggressive in younger animals.

• No breed or sex predilection.

• Often linked to trauma, parasites (Spirocerca lupi), previous radiation therapy, or foreign bodies.

Non-STS Sarcomas

• Rare.

• Includes specific subtypes like hemangiosarcoma, lymphangiosarcoma, and osteosarcoma, which have their own unique patterns of occurrence.

Feline Injection Site Sarcoma (FISS)

• Incidence: 1 per 1,000 to 30,000 vaccinated cats.

• No age, sex, or breed predisposition.

• Strongly associated with killed vaccines (e.g., Rabies, FeLV), possibly due to adjuvants like aluminum.

• Cats may develop tumors 3 months to 3 years post-vaccination.

Malassezia

·       Caused by Malassezia pachydermatis, a lipophilic, nonmycelial yeast.

·       Found as normal flora on canine skin, external ear canal, and mucous membranes.

·       Predisposed by heat, humidity, and concurrent primary skin diseases (e.g., allergies).

·       Breed predisposition: Basset Hound, West Highland White Terrier, Cocker Spaniel, etc.

Atopic Dermatitis

·       Genetic predisposition; barrier dysfunction; IgE to allergens

Food Allergy

·       Unknown; may involve IgE or non-IgE mechanisms

Environmental Allergies

·       Seasonal allergens (pollen, dust mites)

Epidemiology of Otitis Externa, Media, and Interna

1. Otitis Externa:

• Incidence:

  • Common in dogs (affecting approximately 20%) and less common in cats (less than 7%).

• Breed Predisposition:

  • Dogs with pendulous ears (e.g., Cocker Spaniels, Basset Hounds) and narrow ear canals (e.g., Shar Peis).

  • Breeds with increased cerumen production (e.g., Labrador Retrievers).

• Risk Factors:

  • Dogs exposed to moist environments (e.g., swimmers).

  • Underlying allergies (most common cause in dogs).

  • Cats with outdoor exposure or living in shelters are more prone to Otodectes cynotis infestations.

• Etiology:

  • Multifactorial, with predisposing, primary, and perpetuating factors.

  • Frequently associated with allergies (atopic dermatitis, food hypersensitivity).

2. Otitis Media:

• Incidence:

  • Less common than otitis externa but often develops as a sequela of untreated or chronic otitis externa.

  • Seen in both dogs and cats but tends to be undiagnosed due to lack of obvious clinical signs in early stages.

• Pathogenesis:

  • Can occur via:

    • Extension of otitis externa through a ruptured tympanic membrane.

    • Ascending infections through the eustachian tube from the nasopharynx.

    • Trauma or tumors affecting the middle ear.

• Risk Factors:

  • Chronic ear infections.

  • Breeds with a narrow ear canal or prone to hyperplastic changes (e.g., Shar Peis).

  • Cats are predisposed to middle ear polyps.

• Common Pathogens:

  • Bacteria: Pseudomonas, Staphylococcus, Proteus, E. coli.

  • Fungi: Rare, but can occur in immunocompromised animals.

3. Otitis Interna:

• Incidence:

  • Rare but represents a severe progression of otitis media.

  • More commonly diagnosed in dogs than cats due to clinical signs such as vestibular dysfunction.

• Pathogenesis:

  • Develops from:

    • Chronic otitis media.

    • Hematogenous spread of systemic infections.

    • Neurological extension of infectious agents.

• Risk Factors:

  • Untreated or mismanaged otitis media.

  • Prolonged use of ototoxic medications (e.g., certain aminoglycosides) in animals with tympanic membrane rupture.

• Common Signs:

  • Vestibular dysfunction: head tilt, nystagmus, ataxia.

  • Facial nerve paralysis and Horner’s syndrome can occur due to proximity of these structures to the inner ear.

Comparison of Epidemiology:

Epidemiology of Equine Dermatological Diseases

1. Insect Hypersensitivity

• Prevalence: Most common cause of pruritus in horses worldwide.

• Geographical Distribution: Common in regions with high populations of biting insects (e.g., subtropical, tropical, and temperate climates).

• Seasonality: Seasonal in late spring to fall, coinciding with peak insect activity.

• Breed Predilection: Familial predisposition in Welsh ponies, Icelandic ponies, Shires, Arabians, and Quarter Horses.

2. Atopic Dermatitis

• Prevalence: Relatively less common but increasingly recognized in young horses.

• Geographical Distribution: No specific geographic predilection; associated with allergen exposure in stable environments.

• Seasonality: Can be seasonal or non-seasonal, depending on allergen exposure.

• Breed Predilection: Higher incidence in Thoroughbreds and Arabians.

3. Food Hypersensitivity

• Prevalence: Rarely reported in horses.

• Age Group: More common in younger horses.

• Geographical Distribution: No specific geographic predilection; cases are sporadic.

• Associated Factors: Possible concurrent atopic dermatitis or insect hypersensitivity.

4. Alopecia Areata

• Prevalence: Rare autoimmune condition.

• Age, Sex, and Breed Predilections: No known predilections.

• Geographical Distribution: Sporadic cases worldwide.

5. Dermatophytosis

• Prevalence: Common superficial fungal infection.

• Geographical Distribution: Worldwide; particularly common in warm, humid climates.

• Seasonality: Higher incidence in fall and winter in temperate climates.

• Age Predilection: Young horses are more susceptible.

• Contagion: Variable; outbreaks can occur under crowded or unsanitary conditions.

6. Dermatophilosis (Rain Rot)

• Prevalence: Common worldwide.

• Geographical Distribution: Occurs in areas with prolonged wet weather.

• Risk Factors: Chronic skin moisture (e.g., rain, wet bedding), poor hygiene.

• Seasonality: Occurs during wet seasons or in persistently damp conditions.

7. Pemphigus Foliaceus

• Prevalence: Rare but the most common autoimmune skin disease in horses.

• Seasonality: Peaks between September and February; may be linked to hypersensitivity or insect reactions.

• Age, Sex, and Breed Predilections: All ages and breeds affected; no sex predilection.

8. Eosinophilic Granuloma

• Prevalence: Most common non-neoplastic nodular skin disease in horses.

• Seasonality: More common in spring and summer, likely linked to insect activity.

• Risk Factors: Associated with hypersensitivity, trauma (e.g., saddle pressure), or previous clipping.

9. Habronemiasis (Summer Sores)

• Prevalence: Common in warm climates with high fly populations.

• Geographical Distribution: Endemic to tropical and subtropical regions.

• Seasonality: Highly seasonal, occurring during the warmer months.

• Risk Factors: Poor manure management and fly control.

10. Pythiosis

• Prevalence: Rare but severe.

• Geographical Distribution: Endemic in tropical and subtropical areas (e.g., Gulf states of the U.S., Australia, and India).

• Seasonality: Associated with warm, wet conditions and exposure to water.

• Risk Factors: Damaged skin exposed to stagnant water or infected plant material.

11. Pastern Dermatitis

• Prevalence: Common syndrome with various causes.

• Geographical Distribution: Worldwide; associated with environmental or management factors.

• Risk Factors: Prolonged wet or muddy conditions, photosensitization, or parasitic infestations.

• Breed Predilection: Chronic progressive lymphedema variant is more common in Shires, Clydesdales, and Belgian Draft horses.

12. Hereditary Equine Regional Dermal Asthenia (HERDA)

• Prevalence: Rare; primarily affects Quarter Horses (28% of cutting horse bloodlines are carriers).

• Geographical Distribution: Linked to specific bloodlines, traced back to Poco Bueno and related stallions.

• Age of Onset: Typically manifests around 2 years of age, often during saddle-breaking.

• Inheritance: Autosomal recessive.