Dermatophytosis

Question 1

what is the growth requirement for dermatophytes?

Answer 1

require keratin to grow

Question 2

What are the 3 most common dermatophytes isolated in dogs and cats?

Answer 2

Microsporum canis, microsporum gypseum, Trichophyton mentagrophytes

Question 3

Which dermatophyte is most commonly diagnosed in dogs and cats?

Answer 3

M. canis

Question 4

What are the sources/reservoirs for each of the 3 dermatophytes that are common dogs/cats:

Answer 4

M canis- cats
M. gypseum - soil
T. mentagrophytes- rodents

Question 5

What are the different CS for dermatophytosis in dogs and cats:

Answer 5

Dogs- follicular infection, single to multifocal areas of alopecia and scales and crusts, papules, might have some slight pruritus, kerion (abscess caused by a fungal infection) (usually less than 1 yr)
cats- focal to multifocal irregular or annular alopecia with scaling/crusting, generalized dermatitis more common in cats (usually 1 yr old or less and long haired)

Question 6

which dermatophyte can be associated with acantholysis and mimic autoimmune skin disease:

Acantholysis is loss of coherence between epidermal cells due to the breakdown of intercellular bridges

Answer 6

Trichophyton mentagrophytes

Question 7

What are the different diagnostic methods that make us suspect and help diagnose dermatophytosis

Answer 7

Hx, wood lamp exam, Trichogram- check for arthrospores on plucked hair

Question 8

What is the most reliable test for diagnosis of dermatophytosis

Answer 8

Dermatophyte culture (DTM) is the most reliable test and can even identify species

Question 9

What is the common dermatophyte in dogs and cats that fluoresce

Answer 9

M. canis

Question 10

What percent of dermatophyte actually with fluoresce with wood’s lamp???

Answer 10

approx 50% of M. canis

Question 11

What are the tx goals of dermatophytosis

Answer 11

maximize patient’s ability to respond, reduce contagion, achieve resolution of infection efficiently

Question 12

What are the recommended systemic tx for dermatophytosis in the dog and cat?

Answer 12

Cats- Itraconazole
Dogs- Terbinafine, ketoconazole

both- can do fluconazole, griseofulvin

Question 13

How can you monitor for response to tx

Answer 13

clinical response, woods lamp, fungal culture (2-3 successive neg cultures usually within 2-3 weeks apart, PCR testing)

Question 14

How do you determine when tx can be discontinued?

Answer 14

**continue therapy until minimum of 2 sequential neg cultures (aim for 3 in multiple cat households and catteries)