Unit 3 - Dermatology 1 Flashcards
What causes infectious folliculitis?
Dermatophilosis, dermatophytosis, and pyoderma
What does pyoderma result from?
A break in normal physical defenses such as surgical incisions, allergies, endocrine disorders, keratinization disorders, wounds, and trauma
What are the causative agents of pyoderma?
S. aureus (most common), S. pseudintermedius, and S. hyicus
What clinical signs are associated with pyoderma in the horse?
Multiple small papules, pustules, or crusts that are focal or widespread - they have a tendency to coalesce
How is pyoderma diagnosed?
Cytology of the pustules and under crusts, culture, and biopsy
How is pyoderma treated?
Topical or systemic antimicrobials, and address the underlying cause
Is topical or systemic therapy preferred in the treatment of pyoderma? Why?
Topical therapy is preferred because systemic drugs can cause GI upset
What are the options for topical pyoderma therapy?
Chlorhexidine, Benzoyl peroxide, and SSD cream
What are the options for systemic pyoderma therapy?
TMS, enrofloxacin, doxycycline, and ceftiofur
What is dermatophilosis also known as?
rain rot
What causes rain rot?
Dermatophilus congolensis
Why are the crusts caused by rain rot a serious problem?
They are contagious and are the infectious agent
What are the keys to developing rain rot?
Break in the normal skin barrier and moisture
What clinical signs are associated with rain rot?
Papules that progress to thick, painful crusts with an erosive underside
How is rain rot diagnosed?
History and clinical appearance, cytology, and biopsy
What does rain rot look like under the microscope?
railroad tracks
How is rain rot treated?
Place the horse in a dry environment, crust removal, topical chlorohexidine, and potentially systemic therapy (TMS has less GI signs)
What are the etiologic agents of dermatophytosis in horses?
T. equinum, T. verrucosum, and M. equinum
What clinical signs are associated with dermatophytosis in horses?
Very variable, but lesions tend to enlarge with a erythemic, crusted margin - they are not symmetrical
Localize on the head, neck, and forelimbs
How is dermatophytosis diagnosed?
The best option is a fungal culture
How is dermatophytosis treated?
It is a self-limiting illness that typically only lasts 1-4 months so selective isolation is important
Topical therapy and systemic therapy can be used
Where does psoroptic mange localize in the horse?
Head, mane, and tail
How long does psoroptes survive off the host?
14-21 days
How is psoroptic mange treated?
Ivermectin, moxidectin, or eprinomectin
Where does chorioptic mange localize?
the leg and the tail
How long does Chorioptes survive of the host?
70 days
How is chorioptic mange treated?
lime sulfur and fipronil spray
How are parasitic dermatoses in horses spread?
Direct and indirect contact -they are very contagious
What may be required to contain the spread of parasitic dermatoses?
Quarantine of a barn because of the prolonged off-host survival time
True or False: Pastern dermatitis is due to a single etiologic agent.
False - it is not a single disease, it is a reaction pattern - think of it as a syndrome not a diagnosis
What clinical signs are associated with pastern dermatitis?
Localized on the caudal aspect with rear legs affected more commonly
Usually bilateral
Edema, erythema, and scaling which quickly progresses to exudation and crusting
Failure to treat secondary infections and address primary cause leads to chronic changes
What history is important to obtain when addressing pastern dermatitis?
Age of onset seasonal/non-seasonal Pruritic? What has been applied - response? Environmental conditions Are they turned out - what time Other horses affected? How many legs affected? Pigmented vs. non-pigmented Vaccine history Travel? Farrier
How is pastern dermatitis diagnosed?
Skin scrape, cytology, DTM culture, biopsy +/- culture, and blood work
What are the general treatment recommendations for pastern dermatitis?
Attempt to identify the primary cause and provide specific treatment Clean and dry housing Release horses once dew has dried If an irritant or contact allergy is suspected eliminate source Clip the pasterns Frequent cleaning Topical glucocorticoids Systemic antibiotics
What is chronic progressive lymphedema?
Progressive swelling and thickening of the distal extremities
What breed is chronic progressive lymphedema commonly found in?
draft horses
When does chronic progressive lymphedema typically occur(signalment)?
Early onset of 2-4 years of age
What clinical signs are associated with chronic progressive lymphedema?
Progressive scarring and ulcerations of the lower extremities and secondary complications
How is chronic progressive lymphedema diagnosed?
Clinical findings, radiographs, and biopsy
How is chronic progressive lymphedema treated?
Clip the feathers Topical antimicrobial therapy Clear Chorioptes Light exercise Daily skin care Hoof care Decongestive therapy
What age is pastern leukocytoclastic vasculitis associated with?
mature horses
How is pastern leukocytoclassic vasculitis diagnosed?
History, rule out other cause of photosensitization, and biopsy
How is pastern leukocytoclassic vasculitis treated?
Treat the secondary infections - chlorhexidine spray, decrease UV exposure, steroids, pentoxifylline, and prevent subsequent flares
