Unit 3 - Dermatology 1

Question 1

What causes infectious folliculitis?

Answer 1

Dermatophilosis, dermatophytosis, and pyoderma

Question 2

What does pyoderma result from?

Answer 2

A break in normal physical defenses such as surgical incisions, allergies, endocrine disorders, keratinization disorders, wounds, and trauma

Question 3

What are the causative agents of pyoderma?

Answer 3

S. aureus (most common), S. pseudintermedius, and S. hyicus

Question 4

What clinical signs are associated with pyoderma in the horse?

Answer 4

Multiple small papules, pustules, or crusts that are focal or widespread - they have a tendency to coalesce

Question 5

How is pyoderma diagnosed?

Answer 5

Cytology of the pustules and under crusts, culture, and biopsy

Question 6

How is pyoderma treated?

Answer 6

Topical or systemic antimicrobials, and address the underlying cause

Question 7

Is topical or systemic therapy preferred in the treatment of pyoderma? Why?

Answer 7

Topical therapy is preferred because systemic drugs can cause GI upset

Question 8

What are the options for topical pyoderma therapy?

Answer 8

Chlorhexidine, Benzoyl peroxide, and SSD cream

Question 9

What are the options for systemic pyoderma therapy?

Answer 9

TMS, enrofloxacin, doxycycline, and ceftiofur

Question 10

What is dermatophilosis also known as?

Answer 10

rain rot

Question 11

What causes rain rot?

Answer 11

Dermatophilus congolensis

Question 12

Why are the crusts caused by rain rot a serious problem?

Answer 12

They are contagious and are the infectious agent

Question 13

What are the keys to developing rain rot?

Answer 13

Break in the normal skin barrier and moisture

Question 14

What clinical signs are associated with rain rot?

Answer 14

Papules that progress to thick, painful crusts with an erosive underside

Question 15

How is rain rot diagnosed?

Answer 15

History and clinical appearance, cytology, and biopsy

Question 16

What does rain rot look like under the microscope?

Answer 16

railroad tracks

Question 17

How is rain rot treated?

Answer 17

Place the horse in a dry environment, crust removal, topical chlorohexidine, and potentially systemic therapy (TMS has less GI signs)

Question 18

What are the etiologic agents of dermatophytosis in horses?

Answer 18

T. equinum, T. verrucosum, and M. equinum

Question 19

What clinical signs are associated with dermatophytosis in horses?

Answer 19

Very variable, but lesions tend to enlarge with a erythemic, crusted margin - they are not symmetrical
Localize on the head, neck, and forelimbs

Question 20

How is dermatophytosis diagnosed?

Answer 20

The best option is a fungal culture

Question 21

How is dermatophytosis treated?

Answer 21

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

Question 22

Where does psoroptic mange localize in the horse?

Answer 22

Head, mane, and tail

Question 23

How long does psoroptes survive off the host?

Answer 23

14-21 days

Question 24

How is psoroptic mange treated?

Answer 24

Ivermectin, moxidectin, or eprinomectin

Question 25

Where does chorioptic mange localize?

Answer 25

the leg and the tail

Question 26

How long does Chorioptes survive of the host?

Answer 26

70 days

Question 27

How is chorioptic mange treated?

Answer 27

lime sulfur and fipronil spray

Question 28

How are parasitic dermatoses in horses spread?

Answer 28

Direct and indirect contact -they are very contagious

Question 29

What may be required to contain the spread of parasitic dermatoses?

Answer 29

Quarantine of a barn because of the prolonged off-host survival time

Question 30

True or False: Pastern dermatitis is due to a single etiologic agent.

Answer 30

False - it is not a single disease, it is a reaction pattern - think of it as a syndrome not a diagnosis

Question 31

What clinical signs are associated with pastern dermatitis?

Answer 31

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

Question 32

What history is important to obtain when addressing pastern dermatitis?

Answer 32

``` 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 ```

Question 33

How is pastern dermatitis diagnosed?

Answer 33

Skin scrape, cytology, DTM culture, biopsy +/- culture, and blood work

Question 34

What are the general treatment recommendations for pastern dermatitis?

Answer 34

``` 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 ```

Question 35

What is chronic progressive lymphedema?

Answer 35

Progressive swelling and thickening of the distal extremities

Question 36

What breed is chronic progressive lymphedema commonly found in?

Answer 36

draft horses

Question 37

When does chronic progressive lymphedema typically occur(signalment)?

Answer 37

Early onset of 2-4 years of age

Question 38

What clinical signs are associated with chronic progressive lymphedema?

Answer 38

Progressive scarring and ulcerations of the lower extremities and secondary complications

Question 39

How is chronic progressive lymphedema diagnosed?

Answer 39

Clinical findings, radiographs, and biopsy

Question 40

How is chronic progressive lymphedema treated?

Answer 40

``` Clip the feathers Topical antimicrobial therapy Clear Chorioptes Light exercise Daily skin care Hoof care Decongestive therapy ```

Question 41

What age is pastern leukocytoclastic vasculitis associated with?

Answer 41

mature horses

Question 42

How is pastern leukocytoclassic vasculitis diagnosed?

Answer 42

History, rule out other cause of photosensitization, and biopsy

Question 43

How is pastern leukocytoclassic vasculitis treated?

Answer 43

Treat the secondary infections - chlorhexidine spray, decrease UV exposure, steroids, pentoxifylline, and prevent subsequent flares