Unit 3 - Dermatology 2 Flashcards
What type of disorder is Heritable Equine Regional Dermal Asthenia (HERDA)?
Autosomal recessive disorder affecting collagen
What breeds is HERDA common in?
Quarter horses- specifically cutting horse lines
Why are some horses bred for the N/Hrd genotype of HERDA?
Because they have an athletic advantage
What is the age of onset of HERDA?
1.5-2 years of age - may not be observed up to 5 years of age
What clinical signs are associated with HERDA?
Excessive skin trauma and scarring begin at the time of training - temperature and UV light may worsen the condition
Where are lesions associated with HERDA commonly localized?
along the dorsal midline
What ocular issues are associated with HERDA?
Increased incidence of corneal ulceration
What musculoskeletal issues are associated with HERDA?
Increased joint laxity and risk of osteoarthritis
What immune issues are associated with HERDA?
Cyclophilin B mutation (related to T lymphocyte function) and possible increase in infectious disease and neoplasia
How is HERDA diagnosed?
Based on clinical suspicion and genetic testing
How is HERDA managed?
Minimize trauma, good wound management, limit heat and UV exposure, optimize diet for Copper and Vitamin C, joint supplementation
What is the recommended ‘therapy’ for severely affected HERDA animals?
humane euthanasia
What clinical signs are associated with non-inflammatory, non-pruritic alopecia?
No visible lesions other than hair loss
How is non-inflammatory, non-pruritic alopecia diagnosed?
A good history and physical exam will lead to a diagnosis
Biopsy in several samples
When do hair cycle alterations due to Telogen effluvium occur?
After a stressful event
What clinical signs are associated with telogen effluvium hair loss?
1-3 months after stressful event there is wide spread, symmetric hair loss
How is telogen effluvium hair loss diagnosed?
history, trichogram, and biopsy
When does telogen effluvium hair loss resolve?
within 1-2 months
When do hair cycle alterations due to Anagen effluvium occur?
When there is a systemic event
When does hair loss occur with anagen effluvium?
within days of the systemic event
How is anagen effluvium hair loss diagnosed?
Clinical signs +/- a trichogram
When does anagen effluvium hair loss resolve?
1 month
What autoimmune skin diseases do horses get?
Pemphigus foliaceus, pemphigus vulgaris, lupus erythematosus, bullous pemphigoid, erythema multiforme, and vasculitis
What is ‘attacked’ in pemphigus foliaceus?
the desmosome
Generally, what clinical signs are associated with pemphigus foliaceus?
Skin lesions with systemic signs that come in waves
What is the primary lesion of pemphigus foliaceus?
The pustule
What specific clinical signs are associated with pemphigus foliaceus?
Alopecia, scaling, crusting, pain, fever, depression, lethargy, and anorexia
What breeds are commonly affected by pemphigus foliaceus?
Appaloosas, quarter horses, and thoroughbreds
What should your differentials be along side pemphigus foliaceus?
Dermatophytosis, dermatophilosis, pyoderma, multisystemic eosinophilic disease, and sarcoidosis
How is pemphigus foliaceus diagnosed?
Cytology and biopsy
How is pemphigus foliaceus treated?
Immunosuppressive medications - glucocorticoids, injectable gold salts, or azathioprine
Can horses get prednisone?
No - like cats, they are unable to break it down so they should get prednisolone
What is the prognosis for pemphigus foliaceus?
guarded to poor
What can cause viral dermatoses?
Poxvirus, equine herpes, equine viral arteritis, vesicular stomatitis, and papillomatosis
What are the four presentations of equine papillomavirus associated disease?
Classic viral papillomatosis, genital papillomas, aural plaques, and sarcoids
What are aural plaques?
well demarcated hyperkeratotic, non-pigmented plaques that are located on the concave aspect of the pinna
What is the signalment for aural plaques?
any horse greater than a year of age
True or False: Aural plaques are always asymptomatic.
False - they are asymptomatic or may cause head hypersensitivity
Do aural plaques resolve on their own?
nope
How are aural plaques treated?
Cosmetic in most cases - imiquimod or acyclovir
What is the most common allergic skin disease of the horse?
Insect-bite hypersensitivity
What is known as the flea of the horse world?
Culicoides spp.
What does Culicoides eat?
blood
What does the life cycle of Culicoides require?
free standing water
What is the signalment of Culicoides allergies?
Seasonal to non-seasonal
Onset of 3-4 years of age, worsens with age, and is genetic
What breeds are predisposed to Culicoides allergies?
Ponies, icelandic breeds, quarter horses, and arabians
What about Culicoides causes hypersensitivity?
Their salivary antigens
Where do lesions due to Culicoides localize?
dorsal or ventral midline
What clinical signs are associated with Culicoides allergies?
Intense pruritus, traumatic alopecia, papules, crusting, lichenification and scaling, eosinophilic collagenolytic granulomas (nodules)
What complications are associated with Culicoides allergies?
Secondary infections, severe self-trauma, behavior issues, body condition issues, and euthanasia
What should be ruled out before deciding that Culicoides is the cause of insect-bite hypersensitivity?
Parasites - Oxyuris equi, lice, and psoroptic or chorioptic mange
Non-culicoides insect hypersensitivities
Environmental allergies
How is Culicoides allergy treated?
Prevent additional bites, control itch (steroids), and treat secondary infections
What insect control can you use for horses?
Destroy their environment or move the horse
Repellent
Stabling
Fans or breezy patures
What itch relief/control can be used for insect-bite hypersensitivities?
Antihistamines, local anesthetics, glucocorticoids (topical or systemic), and long-term prevention
What are the antihistamines of choice for insect-bite hypersensitivities?
Cetirizine and hydroxine
When are horse and deer flies problematic?
Summer months
What do horse and deer flies require for their lifecycle?
vegetation around water
What are horse and deer flies vectors for?
EIA and papillomavirus
When do horse and deer flies feed?
during the day
What type of water do Simulium spp. (black flies, buffalo gnats, and sandflies) live by?
Running water
If a horse is allergic to Simulium, what else is it allergic to?
Culicoides - the salivary proteins are cross-reactive with this
Where do Simulium spp like to feed? When?
They feed on thin haired areas at the morning and evening
What are Simulium spp vectors for?
Onchocerca and papillomavirus
When is Simulium spp bites associated with death?
When they attack in swarms
What is equine ectopic disease?
A pruritic, inflammatory condition that is triggered by an environmental allergen
What other syndromes get lumped in with equine ectopic disease?
Recurrent airway disease, recurrent urticaria, and idiopathic head-shaking syndrome
What is the signalment for equine ectopic disease?
Young-middle age horses - possibly thoroughbreds
What is the primary clinical sign associated with equine ectopic disease? Where?
Pruritus of the face, legs, and trunk
How is equine ectopic disease diagnosed?
Clinical history and exclusion of other pruritic skin conditions - there is no definitive test
How is equine ectopic disease treated?
Topical therapy - rinse coat, hydrate skin, and treat secondary infections
Antihistamines
Glucocorticoids
Allergen-specific immunotherapy (ASIT)
What is recurrent urticaria?
Raised papules to plaques to patches that pit on gentle pressure
What breeds is recurrent urticaria commonly found in?
Thoroughbreds and Arabians
What length duration is acute recurrent urticaria associated with?
8 weeks or less
What length duration is chronic recurrent urticaria associated with?
8 weeks or longer
What are the 6 clinical forms of recurrent urticaria?
Conventional, papular, giant, exudative, gyrate, and linear
Describe conventional recurrent urticaria.
Classic wheals varying in size from 0.5-5cm - vasculitis
Describe papular recurrent urticaria.
Uniform small papules (3-8mm size) - associated with insects
Describe giant recurrent urticaria.
Excessively large wheals - vasculitis
Describe exudative recurrent urticaria.
Serum oozing, matting of hairs, and alopecia
Describe gyrate recurrent urticaria.
Bizarre shapes, erythema multiforme
Describe linear recurrent urticaria.
Zebra stripes
True or False: There are many causes of recurrent urticaria
True - I doubt he will make us list any because there are 15 categories
How is recurrent urticaria diagnosed?
History, clinical findings, and biopsy
How is recurrent urticaria treated?
Symptomatic - glucocorticoids and antihistamines
Specific based on underlying cause
