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119 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 Dermatófitos isolados de cães 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 commonfungal 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, Paraná 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 fungal specie in both cats and dogs was Microsporum canis , which was isolated in 68.5% of the positive cultures fordermatophytes in dogs’ samples, being the only species recovered from cats’ cultures. Malassezia pachydermatis was the mostcommonly isolated yeast from the skin of dogs. Acari, mainly Demodex canis , were found in 5.0% of all samples with suspecteddiagnosis of dermatophytosis. Key words: dermatophytosis, cat, dog, Microsporum, Trichophyton . RESUMO Dermatofitose que é caracterizada por uma infecção superficial confinada aos tecidos queratinizados, é a doençafúngica mais comum na medicina veterinária de pequenos animais. O diagnóstico de dermatofitose com base apenas nos sinaisclínicos é incerto, não somente pela natureza variável dos achados dermatológicos, mas também porque há várias outras doençasde pele que mimetizam a lesão fúngica típica (lesões circulares com alopecia). O presente estudo reporta resultados laboratoriaisde uma extensiva pesquisa avaliando etiologia fúngica e parasitária de doenças de pele através da análise de 1240 amostras decrostas provenientes de unhas e pele de cães e gatos com suspeita clínica de dermatofitose. As amostras coletadas em váriasclínicas veterinárias dos estados de Santa Catarina, Paraná e Rio Grande do Sul, principalmente da cidade de Santa Maria noRio Grande do Sul, foram processadas no Laboratório de Pesquisas Micológicas da Universidade Federal de Santa Maria, Suldo Brasil, entre 1998 e 2003. Entre as amostras de caninos e felinos, a percentagem de espécimes positivas para dermatófitosforam 10,2% e 27,8%, respectivamente. A espécie fúngica mais prevalente tanto nos cães como nos gatos foi Microsporum canis ,a qual foi isolada em 68,5% das amostras de cães, sendo a única espécie recuperada de culturas de gatos. Malassezia pachydermatis foi a levedura mais comumente isolada da pele de cães. Ácaros, principalmente Demodex canis , foram encontrados em 5,0%das amostras totais com diagnóstico suspeito de dermatofitose. Descritores: Dermatofitose, cão, gato, Microsporum , Trichophyton . Laboratório de Pesquisas Micológicas, Universidade Federal de Santa Maria (UFSM). CORRESPONDENCE: J.M. Santurio [
[email protected]]. Received: December 2005 Accepted: March 2006www.ufrgs.br/favet/revista 120 Copetti M.V., Santurio J.M., Cavalheiro A.S., Boeck A.A., Argenta J.S., Aguiar L.C. & Alves S.H. 2006. Dermatophytes isolatedfrom 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 clinicalveterinary medicine in small animals. The dermatophy-te agents mainly belonged to the genera Microsporum and Trichophyton . These fungi produce keratinasesand others enzymes capable to digest the keratin pro-tein complex, allowing the dermatophyte to burrowdeeper into the stratum corneum in 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 unreliableon 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 of Santa 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 28ºC 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 agentswas 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 37°Cand 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 relativeoccurrence according to the animal species. A total of 220 (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. mentagrophytes were 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 Candidaalbicans isolated from pets in this survey were relatedto a history of interdigital dermatitis.Acari were found in 4.7% of the samples withclinical suspicion of dermatophytosis, mixed infec-tions with Demodex canis and M. canis were observedin 4 (0.4%) specimens collected from dogs. Likewise, Notoedres cati was associated with M. canis in 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 121 Copetti M.V., Santurio J.M., Cavalheiro A.S., Boeck A.A., Argenta J.S., Aguiar L.C. & Alves S.H. 2006. Dermatophytes isolatedfrom dogs and cats suspected of dermatophytosis in Southern Brazil. Acta Scientiae Veterinariae. 34: 119-124. seicepSlaminA eninaC selpmas )9801( )%(enileF selpmas )151( )%(latoT rebmun )0421( )%(SETYHPOTAMRED 701 )8.9( 14 )2.72( 841 )21( s i n a c m u r o p s o r c i M 27 )6.6( 83 )2.52( 011 )9.8( s i n a c .M .rav m u t r o t s i d 1 )1.0( 3 )0.2( 4 )3.0( m u e s p y g .M 33 )0.3( 0 - 33 )7.2( s e t y h p o r g a t n e m n o t y h p o h c i r T 1 )1.0( 0 - 1 )1.0( STSAEY 36 )8.5( 4 )6.2( 76 )4.5( s n a c i b l a a d i d n a C 6 )6.0( 2 )3.1( 8 )6.0( s n a m r o f o e n s u c c o c o t p y r C 0 - 2 )3.1( 2 )2.0( s i t a m r e d y h c a p a i z e s s a l a M 14 )7.3( 0 - 14 )3.3( deifitneditoN 01 )9.0( 0 - 01 )8.0( IGNUFSREHTO 6 )6.0( 0 - 6 )5.0( i i k c n e h c s x i r h t o r o p S 6 )6.0( 0 - 6 )5.0( IRACA 15 )7.4( 7 )7.4( 85 )7.4( s i n a c x e d o m e D 43 )1.3( 0 - 43 )7.2( i t a c s e r d e o t o N 0 - 6 )0.4( 6 )5.0( s i t o n y c s e t c e d o t O 1 )1.0( 0 - 1 )1.0( i e i b a c s s e t p o c r a S 61 )5.1( 1 )7.0( 71 )4.1( )SETYHPOTAMRED&IRACA(DEXIM 4 )4.0( 1 )7.0( 5 )4.0( s i n a c .D + s i n a c .M 4 )4.0( 0 - 4 )3.0( i t a c .N + s i n a c .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 ratioof positive cultures in relation to the samples exami-ned present a great variation when the specimens un-der evaluation are srcinated 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 that Microsporum canis is the most prevalent dermatophyte isolated from theskin of suspected animals, which is in agreement withthis survey. Microsporum canis , along with M. gypseum and Trichophyton mentagrophytes , are the fungal spe-cies responsible for more than 95% of all dermatophy-tosis cases in pets. Geophilic dermatophytes were justisolated from dogs. This selective predominance canbe explained considering the most frequent associa- 122 Copetti M.V., Santurio J.M., Cavalheiro A.S., Boeck A.A., Argenta J.S., Aguiar L.C. & Alves S.H. 2006. Dermatophytes isolatedfrom dogs and cats suspected of dermatophytosis in Southern Brazil. Acta Scientiae Veterinariae. 34: 119-124. yrtnuoC doireP srohtuA sgoD staC )n(selpmaS )%(evitisoP )n(selpmaS )%(evitisoP modgniKdetinU 65-5591 nipeP .l a t e ]01[ 826 0.7 423 6.9 dnalniF 97-7791 ]11[ohA 602 9.3 16 3.12 lizarB 28-9791 orierreF .l a t e ]21[ 532 5.41 72 6.92 yawroN 48-1891 ]31[gniwnetS 087 5.5 972 8.03 ylatI 78-5891 iggaF .l a t e ]41[ 591 3.33 963 6.34 ASU 09-1891 siweL .l a t e ]9[ 4281 8.3 804 9.41 modgniKdetinU 19-6591 sekrapS .l a t e ]51[ 2494 6.9 7043 2.62 airtsuA 19-8891 ]61[grebsortS-reuerB 636 4.21 483 3.05 niapS 59-6891 señabaC .l a t e ]71[ 501 3.41 65 9.33 ylatI 7891 atteraC .l a t e ]81[ 861 7.92 39 4.36 ylatI s'0991 oisihcraM .l a t e ]6[ 89 4.53 501 6.46 aitaorC 89-0991 retniP .l a t e ]91[ 3533 3.51 838 7.04 ynamreG 59-3991 ]02[tdimihcS 59 12.4 87 35.11 narI 89-4991 ivarsohK .l a t e ]12[ 79 8 681 55 lizarB 10-0002 etnahlirB .l a t e ]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. persicolor from dogs wasobserved in this study. There are no reports of theoccurrence of M. persicolor in 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 thiscountry. 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 of M. 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 of M. gypseum in dogswas relatively similar to our data (20.6%). Alternatively, [4] described a prevalence of 3.7% of M. gypseum re-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. gypseum and 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 samplecollection 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-
