Dermatofitosis Pada Anjing

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Acta Scientiae Veterinariae. 34(2): 119-124, 2006.

ORIGINAL ARTICLE

Pub. 661

ISSN 1678-0345 (Print)

ISSN 1679-9216 (Online)

Dermatophytes isolated from dogs and catssuspected of dermatophytosis in Southern Brazil

Dermatfitos isolados de ces e gatos com suspeita de dermatofitose no sul do Brasil

Marina Venturini Copetti, Janio Morais Santurio, Ayrton Sydnei Cavalheiro,

Ana Aurea Boeck, Juliana Siqueira Argenta, Leila Canabarro Aguiar & Sydney Hartz Alves

ABSTRACT

Dermatophytosis which is characterized by a superficial infection confined to keratinised tissues, is the most common

fungal disease in small animal veterinary medicine. It is unreliable to diagnose dermatophytosis on the basis of clinical signsalone, not only for the variable nature of the dermatological findings but also because there are several other skin diseases whichmimic the typical fungal lesion (circular lesions with alopecia). The present study reports laboratory results of an extensive surveyevaluating fungal and parasitic aetiology of skin diseases through the analysis of 1,240 fur, nails and skin scraping specimensfrom dogs and cats with clinical suspicion of dermatophytosis. Samples collected in several veterinary clinics of the SantaCatarina, Paran and Rio Grande do Sul states, mainly of the Santa Maria city in Rio Grande do Sul, were processed at theMycology Research Laboratory of the Federal University of Santa Maria, Southern Brazil, between 1998 and 2003. Amongcanine and feline samples, the percentages of positive dermatophyte specimens were 10.2% and 27.8%, respectively. The mostprevalent fungalspecie in both cats and dogs wasMicrosporum canis, which was isolated in 68.5% of the positive cultures fordermatophytes in dogs samples, being the only species recovered from cats cultures.Malassezia pachydermatiswas the mostcommonly isolated yeast from the skin of dogs. Acari, mainlyDemodex canis, were found in 5.0% of all samples with suspecteddiagnosis of dermatophytosis.

Key words: dermatophytosis, cat, dog,Microsporum,Trichophyton.

RESUMO

Dermatofitose que caracterizada por uma infeco superficial confinada aos tecidos queratinizados, a doenafngica mais comum na medicina veterinria de pequenos animais. O diagnstico de dermatofitose com base apenas nos sinaisclnicos incerto, no somente pela natureza varivel dos achados dermatolgicos, mas tambm porque h vrias outras doenasde pele que mimetizam a leso fngica tpica (leses circulares com alopecia). O presente estudo reporta resultados laboratoriaisde uma extensiva pesquisa avaliando etiologia fngica e parasitria de doenas de pele atravs da anlise de 1240 amostras decrostas provenientes de unhas e pele de ces e gatos com suspeita clnica de dermatofitose. As amostras coletadas em vrias

clnicas veterinrias dos estados de Santa Catarina, Paran e Rio Grande do Sul, principalmente da cidade de Santa Maria noRio Grande do Sul, foram processadas no Laboratrio de Pesquisas Micolgicas da Universidade Federal de Santa Maria, Suldo Brasil, entre 1998 e 2003. Entre as amostras de caninos e felinos, a percentagem de espcimes positivas para dermatfitosforam 10,2% e 27,8%, respectivamente. A espcie fngica mais prevalente tanto nos ces como nos gatos foiMicrosporum canis,a qual foi isolada em 68,5% das amostras de ces, sendo a nica espcie recuperada de culturas de gatos.Malassezia pachydermatisfoi a levedura mais comumente isolada da pele de ces. caros, principalmenteDemodex canis, foram encontrados em 5,0%das amostras totais com diagnstico suspeito de dermatofitose.

Descritores:Dermatofitose, co, gato,Microsporum,Trichophyton.

Laboratrio de Pesquisas Micolgicas, Universidade Federal de Santa Maria (UFSM). CORRESPONDENCE: J.M. Santurio [[email protected]].

Received: December 2005 Accepted: March 2006www.ufrgs.br/favet/revista


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Copetti M.V., Santurio J.M., Cavalheiro A.S., Boeck A.A., Argenta J.S., Aguiar L.C. & Alves S.H. 2006. Dermatophytes isolated

from dogs and cats suspected of dermatophytosis in Southern Brazil. Acta Scientiae Veterinariae. 34: 119-124.

INTRODUCTION

Dermatophytosis which is characterized by asuperficial skin infection confined to keratinised epi-thelium, is the most common fungal disease in clinical

veterinary medicine in small animals. The dermatophy-te agents mainly belonged to the generaMicrosporumand Trichophyton. These fungi produce keratinasesand others enzymes capable to digest the keratin pro-tein complex, allowing the dermatophyte to burrowdeeper into the stratum corneumin the host and there-fore to elicit an inflammatory reaction [7,11]. The degreeof inflammation, dependent of host-fungus interaction,determines the degree and significance of the clinicalsigns.

The diagnosis of dermatophytosis is unreliable

on the basis of clinical signs exclusively, not only dueto the variable nature of the dermatological findings,but also because there are several other skin diseasesthat mimic the typical dermatophytic lesion (circularlesions with alopecia). Demodicosis and dermatophy-tosis can be clinically indistinguishable, but can be re-liably distinguished by skin scraping. Moreover, su-perficial folliculitis, especially when the spreading ringsof erythema and exfoliation are also present, is of-ten mistaken for dermatophytosis [10].

This study reports laboratory results of an ex-

tensive survey evaluating fungal and parasitic aetio-logy of skin diseases in dogs and cats with clinicalsuspicion of dermatophytosis through the analysisof specimens addressed to the Mycology ResearchLaboratory, southern Brazil, between 1998 and 2003.

MATERIALS & METHODS

A total of 1,240 samples composed of fur,nail and skin scraping specimens were collected from1,089 (87.8%) dogs and 151 (12.2%) cats with clini-

cal suspicion of dermatophytosis in several veterinaryclinics, and submitted by veterinarians to the Myco-logy Research Laboratory of the Federal University ofSanta Maria, in Southern Brazil. Each sample cor-responds to an animal, and can be composed by subsamples collected from different lesions. All sampleswere examined by direct microscopy and were cultured.

Specimens were both examined for fungal ele-ments and acari by direct microscopy in 20% potas-sium hydroxide and inoculated on Micobiotic Agarand/or Sabouraud Chloramphenicol Agar slants. Cul-

tures were incubated at 28C and examined daily for15 days. Each developing colony, morphologically com-

patible with dermatophytes, was subcultured on Lactri-mel agar, under the same incubation conditions des-cribed above, for the induction of conidiation.

The laboratory identification of etiologic agents

was based on micro and macroscopic characteristics.In addition, the urease and the in vitro hair perforationtests, the evaluation of nutritional requirements in cul-ture, sugars assimilation, capability to growth at 37Cand the ability to produce germ tubes were also carriedout to differentiate fungal species.

RESULTS

Table 1 displays the list of fungal agents iden-tified in specimens collected from cats and dogs withclinical diagnosis of dermatophytosis and their relative

occurrence according to the animal species. A total of220 (17.7%) out of 1,240 samples were positive to my-cotic agents; among those, dermatophytes were iden-tified in 153 (12.3%) samples. Misdiagnoses with aca-riosis were found in 58 (4.7%) of all examined samples.

Direct microscopy of samples was positive in76 (68.47%) of 111 culture positive from dogs, andin 24 (57.14%) of 42 culture positive from cats. Thepercentages of samples positive for dermatophytes fromcanine and feline specimens were 9.8% and 27.2%,respectively. Microsporum canis was the most preva-

lent fungal species observed in those specimens. Itwas recovered from 68.5% of the positive cultures fordermatophytes from dogs, and was the only fungusto be recovered from cat specimens. In addition, M.gypseum and T. mentagrophyteswere also isolated inspecimens from dogs.

Among yeasts, Malassezia pachydermatis indogs, and Cryptococcus neoformans and Candidaalbicans in cats, were the most prevalent agents iso-lated from animals with skin diseases. Most Candida

albicansisolated from pets in this survey were relatedto a history of interdigital dermatitis.Acari were found in 4.7% of the samples with

clinical suspicion of dermatophytosis, mixed infec-tions withDemodex canisandM. caniswere observedin 4 (0.4%) specimens collected from dogs. Likewise,

Notoedres catiwas associated withM. canisin 1 (0.7%)cat specimen.

DISCUSSION

Fungal skin disease is considered to be clini-

cally overdiagnosed in veterinary medicine, especiallyin dogs [15]. Studies evaluating the aetiology of skin


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SETYHPOTAMRED 701 )8.9( 14 )2.72( 841 )21(

sinacmuropsorciM 27 )6.6( 83 )2.52( 011 )9.8(

sinac.M .rav mutrotsid 1 )1.0( 3 )0.2( 4 )3.0(

muespyg.M 33 )0.3( 0 - 33 )7.2(

setyhporgatnemnotyhpohcirT 1 )1.0( 0 - 1 )1.0(

STSAEY 36 )8.5( 4 )6.2( 76 )4.5(

snaciblaadidnaC 6 )6.0( 2 )3.1( 8 )6.0(

snamrofoensuccocotpyrC 0 - 2 )3.1( 2 )2.0(

sitamredyhcapaizessalaM 14 )7.3( 0 - 14 )3.3(

deifitneditoN 01 )9.0( 0 - 01 )8.0(

IGNUFSREHTO 6 )6.0( 0 - 6 )5.0(

iikcnehcsxirhtoropS 6 )6.0( 0 - 6 )5.0(

IRACA 15 )7.4( 7 )7.4( 85 )7.4(

sinacxedomeD 43 )1.3( 0 - 43 )7.2(

itacserdeotoN 0 - 6 )0.4( 6 )5.0(

sitonycsetcedotO 1 )1.0( 0 - 1 )1.0(

ieibacssetpocraS 61 )5.1( 1 )7.0( 71 )4.1(

)SETYHPOTAMRED&IRACA(DEXIM 4 )4.0( 1 )7.0( 5 )4.0(

sinac.D + sinac.M 4 )4.0( 0 - 4 )3.0(

itac.N + sinac.M 0 - 1 )7.0( 1 )1.0(

EVITAGEN 468 )3.97( 89 )9.46( 269 )6.77(

Table 1.Laboratory results of cutaneous scrapings from dogs and cats with dermatophytosis suspicion.

diseases in dogs and cats by fungal cultures indicatedthat the prevalence of dermatophytes might be as lowas 2% of all dermatologic cases [10]. However, the ratio

of positive cultures in relation to the samples exami-ned present a great variation when the specimens un-der evaluation are originated from animals clinicallysuspected of dermatophytosis, which can be easily re-cognized by assessing reports of surveys carried outin a number of countries (Table 2). This variation alle-gedly occurs due to differences in temperature, clima-te, relative humidity and precipitation among the geo-graphical regions where the surveys were executed[13], along with the degree of experience of clinicianscollecting the samples.

The prevalence of dermatophytes in dogs withsuspected lesions of dermatophytosis is relatively low,

usually ranging between 4% and 15% [2-5,9,12,13,16,17,19,20,21]. These data are in accordance with the resultsobtained in our laboratory, but considerably higher va-

lues have been reported elsewhere [6,8,14]. In cats, theprevalence of dermatophytosis is usually higher thanin dogs, with values higher than 20% being reportedin most cases [3-6,12,14,17,20].

Most studies indicated thatMicrosporum canisis the most prevalent dermatophyte isolated from theskin of suspected animals, which is in agreement withthis survey.Microsporum canis, along withM. gypseumand Trichophyton mentagrophytes, are the fungal spe-cies responsible for more than 95% of all dermatophy-tosis cases in pets. Geophilic dermatophytes were just

isolated from dogs. This selective predominance canbe explained considering the most frequent associa-


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yrtnuoC doireP srohtuAsgoD staC

)n(selpmaS )%(evitisoP )n(selpmaS )%(evitisoP

modgniKdetinU 65-5591 nipeP .late ]01[ 826 0.7 423 6.9

dnalniF 97-7791 ]11[ohA 602 9.3 16 3.12

lizarB 28-9791 orierreF .late ]21[ 532 5.41 72 6.92

yawroN 48-1891 ]31[gniwnetS 087 5.5 972 8.03

ylatI 78-5891 iggaF .late ]41[ 591 3.33 963 6.34

ASU 09-1891 siweL .late ]9[ 4281 8.3 804 9.41

modgniKdetinU 19-6591 sekrapS .late ]51[ 2494 6.9 7043 2.62

airtsuA 19-8891 ]61[grebsortS-reuerB 636 4.21 483 3.05

niapS 59-6891 seabaC .late ]71[ 501 3.41 65 9.33

ylatI 7891 atteraC .late ]81[ 861 7.92 39 4.36

ylatI s'0991 oisihcraM .late ]6[ 89 4.53 501 6.46

aitaorC 89-0991 retniP .late ]91[ 3533 3.51 838 7.04

ynamreG 59-3991 ]02[tdimihcS 59 12.4 87 35.11

narI 89-4991 ivarsohK .late ]12[ 79 8 681 55

lizarB 10-0002 etnahlirB .late ]22[ 981 3,41 83 8,63

Table 2.Occurrence of dermatophytes in dogs and cats with suspicion of dermatophytosis in different countriesaccording to literature.

tion of dogs with soil during traditional walks, in thehouses patio or living in rural areas. Cats are usuallykept inside the houses, restricting contact with theagents reservoir.

In contrast to others reports, especially fromEurope, no isolation of M. persicolorfrom dogs wasobserved in this study. There are no reports of theoccurrence ofM. persicolorin animals in Brazil; how-ever, in 1975, reported the first human case causedby this agent in this country [18]. It is inferred that thisfungus, has little epidemiological importance in this

country. On the other hand, the prevalence of M.gypseum in dogs in southern Brazil is considerablyhigher than values reported from Europe and UnitedKingdom (29.7% vs.15.0% or less, respectively) [2,3,5,6,8,14,16,17,19-21].

Comparing the relatively high occurrence ofM. gypseum in this study with other two reports docu-mented in Brazil, we found contrasting results depen-ding on the geographic area. In a study [9], also carriedout in Southern Brazil, but concentrated in a more me-tropolitan area, the prevalence ofM. gypseumin dogs

was relatively similar to our data (20.6%). Alternatively,[4]described a prevalence of 3.7% ofM. gypseumre-

covered from dogs in Northeast Brazil. These distinc-tions may be mainly explained by climatic and geo-graphic differences. However, the dermatophyte spe-cies (M. canis, M. gypseumand T. mentagrophytes)recovered from dogs and cats were similar among thosestudies, including this current. The rate of prevalenceof dermatophytosis obtained in our survey was slightlylower than in other reports from Brazil. Regardingthis issue, [13]indicated that when the number of sub-mitted samples increases, the percentage of positivecultures tends to decrease. In our case, as the sample

collection was at no cost for the pet owners, a fairlyhigh number of material samples were retrieved forthis study, which may have contributed to the relati-vely lower rate of dermatophytosis [13].

The positive values observed by direct exami-nation of allegedly positive samples were similar toresults obtained yet [4], but higher than the resultsfrom others authors [5,20](61.4%, 61.0%, 58.8%, and55.0%, respectively). Twenty-five samples from ani-mals under therapy turned positive on direct micros-copy, but remained negative in culture.

Generally, clinical signs of dermatophytosis arehighly variable and depend on the host-fungus inte-


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raction and the degree of the subsequent inflamma-tion. Consequently, clinical symptoms may vary fromasymptomatic, to patchy hair loss, a papulocrustouseruption, an exfoliative dermatosis, erythematous pla-ques, and to a suppurative nodular disorder (kerionreaction) [10]. As a result, this infection can mimic manyother diseases, such parasitism, bacterial infections,allergies, immunologic diseases, nutritional related der-matosis, hormonal disorders, some skin cancers andkeratinisation disorders [1]. These issues may justifyeither the relatively low rate of laboratorial confirma-tion of dermatophytes in dogs with suspected lesionsof dermatophytosis, or the misdiagnosis with acari,found in 4.7% of the samples. Since samples processedin this study were collected in distinct veterinary cli-

nics, and most clinicians do not usually disclose thecomplete clinical history of their patients, we did nothave access to the animals with skin disorders. Con-sequently, it became difficult to reconcile the clinicalsigns and the laboratory results to the misdiagnoses.

Yeast infections in dogs are usually the resultof Malassezia pachydermatis. This is considered anormal resident of the skin and an opportunistic patho-gen, thus only cultures presenting high number ofcolonies were accounted in this study. Malasseziosiscan be a primary problem but is more commonly seenas a secondary infection and tends to complicate otherproblems, especially allergies, keratinisation disor-ders, skin fold dermatitis, immunodeficiency and pre-vious antibiotic administration. Candidosis is rare inpets, and predominantly causes mucocutaneous disea-

ses and interdigital dermatitis, being typically associa-ted with immune dysfunction and antimicrobial the-rapy [1]. It is assumed that S. schenckiiwere isolatedfrom dogs presenting initial development of disease,since the lesions in this stage resembled dermatophy-tosis. Diseases that cause imunosuppression have beenassociated with cryptococcal infections; however wedid not performed further analyses for concurrent viralinfectious diseases in the subject cats used in this study.

Since yeast isolation from dogs and cats provi-des only supportive evidence of infection, histopatho-logic studies are required to confirm the diagnosis [1,10].Hence, in cases where Candida orMalassezia wereisolated from skin scrapings, we have emphasized toveterinary clinicians that such findings do not necessa-

rily imply that the yeasts were the primary cause of theskin disorder.

Considering that only 12% (148/1,240) of allsuspected samples directed to our laboratory were po-sitively confirmed, it becomes evident that many ani-mals presenting skin lesions by the clinical examina-tion are misdiagnosed with dermatophytosis. This em-phasizes the difficulty to perform an immediate diagno-sis of dermatophytosis, which may lead to mistreat-ment in a number of cases. Consequently, we conclu-de that the laboratory diagnosis of dermatophytosis isnecessary for the most efficient treatment or manage-ment decision to be made in a case-by-case basis.

Acknowledgements. The authors thank all LAPEMI memberswho have cooperated with the processing of specimens, andall veterinarians that provided material for this study.

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2 Aho R. 1980.Studies on fungal flora in hair from domestic and laboratory animals suspected of dermatophytosis. I. Dermatophytes.Acta Pathologica et Microbiologica Scandinavica. 88: 79-83.

3 Breuer-Strosberg R. 1993. Reported frequency of dermatophytes in cats and dogs in Austria.Deutsche Tierarztliche Wochen-schrifte. 100: 483-85.

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5 Cabaes F.J., Abarca M.L. & Bragulat M.R. 1997.Dermatophytes isolated from domestic animals in Barcelona, Spain.Mycopathologia. 137: 107-113.

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9 Ferreiro L., Ferreiro C.L.R. & Soares H.C. 1982-83.Etiologia das dermatomicoses de animais domsticos, com especialnfase nas dermatofitoses. Levantamento durante um perodo de 3 anos (1979-1982) no Laboratrio de Doenas Infecciosas,da Faculdade de Veterinria da UFRGS, Porto Alegre, RS, Brasil.Arquivos da Faculdade de Veterinria UFRGS.10-11: 85-92.

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11 Jungerman P.F. & Schwartzman R.M. 1972.Microsporosis and Trichophytosis. In: Veterinary Medical Mycology. Philadelphia:Lea & Febiger, pp.3-28.

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State University 1981-1990. Veterinary Dermatology. 2: 53-58.14 Marchisio V.F., Gallo M.G., Tullio V., Nepote S., Piscozzi A. & Cassinelli C. 1995. Dermatophytes from cases of skin disease

in cats and dogs in Turin, Italy.Mycoses.38: 239-244.15 Moriello K.A. 2004.Treatment of dermatophytosis in dogs and cats: review of published studies. Veterinary Dermatology.

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