Dermatophytosis (Ringworm)

stef artMarina-Ştefania Stroe, DVM



Dog, yorkshire terrier, F, 6 years old, spayed, vaccinated, dewormed and with fleas and ticks treatment done, 2 kg. She has been scratched for 2 weeks. A new cat was brought home three weeks ago. The cat present areas of alopecia on the tail.


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fig 1

Circumscribed lesions on the shoulder (Fig. 1) and on ventral cervical region (Fig. 3), areas of round shaped alopecia with erythema, scaling.

Remaining hairs may appear broken off.

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fig 2

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fig 3

Positive Wood’s lamp examination – apple green glow associated with the root of each hair (Fig. 2)

Matt fur examined with Wood’s lamp:

auricular pavilion (Fig. 4) and cervical ventral (Fig. 5) positive, fluorescent hairs.

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fig 4


fig 5

A true dermatophyte infection reveals an apple green fluorescence on the roots of the hair.




Fig. 6: Microscopic examination – hair with modified structure of medulla and cortex.

Dermatophytosis (Ringworm)

Other differentials (ex. demodicosis, superficial pyoderma).

Wood’s lamp examination: typical yellowish-green fluorescent hair shafts that can be given by Microsporum canis strains; only Microsporum canis fluoresces and in only about half of cases. The Wood’s lamp is useful in establishing a tentative diagnosis of dermatophytosis in dogs and cats but false-negative and false-positive results are common. Definitive diagnosis is established by DTM culture.

Trichogram: misshapen hair shafts infiltrated with hyphae and arthrospores.

Deep skin scraped: negative


Topical antifungal treatment applied on whole body twice a week, for 6-8 weeks until the result of the DTM culture is negative. Bathing are recommended to be done with shampoo containing chlorhexidine and an antifungal (ex ketoconazole) after the animal has been clipped. Ointment containing clotrimazole applied locally in thin layer, daily.

Environment: Decontamination measures in the house, where the animal stood (changed and washed carpets, bedding, beds, pillows), taking all measures to remove spores.

Supplements based on Omega 3 and Omega 6, which will help reduce pruritus and inflammation.


The prognosis is good. However, it should not be forgotten that dermatophytosis is a contagious disease that can be transmitted to other animals and humans.