"Carry-on" dermal baggage: a nodule from a dog. Pyogranulomatous inflammation with intralesional fungal agents

A 2-year-old intact female Australian Cattle Dog presented with a 1-cm diameter nonexudative dermal nodule on the medial aspect of the right thigh. Fine-needle aspiration revealed pyogranulomatous inflammation and many ovoid, 2-4 microm diameter, thin-capsulated, basophilic bodies that appeared to be fungal spores or yeast. Results of CBC, serum chemistry panel, lymph node palpation, and radiographs were unremarkable. Excisional biopsy and histopathology revealed pyogranulomatous folliculitis, furunculosis, and perifolliculitis. Rare fungal hyphae and spore forms were intimately associated with, and occasionally within, hair shafts. A morphologic diagnosis of dermatophytosis was made and Microsporum canis infection was confirmed by fungal culture. M canis is a common infectious agent found within the follicles and superficial keratin layers of canine skin. The kerion-type clinical presentation observed in the dog of this case is uncommonly observed with M canis. Additionally, the cytologic finding of multiple arthroconidia without hyphae is unusual. In the absence of hyphae, M canis arthroconidia may be confused with other fungal yeast bodies; therefore close scrutiny of a cytologic sample for arthroconidia associated with keratin, hair fragments, or hyphal structures is recommended.     

Diagnostic techniques for dermatophytosis

This article reviews the use of common diagnostic tools for the identification and isolation of dermatophyte infections in small animals. The use of the Wood's lamp as a screening tool is discussed, along with its usefulness as an aid in the microscopic examination of hairs for fungal elements. Tests for the definitive diagnosis of dermatophytosis are highlighted and include: direct examination of hair for ectothrix spores, fungal cultures, and skin biopsy. Sampling techniques, procedures, and interpretation of test results are also detailed.     

P-15 Identification of Malassezia spp. isolated from a cat and cattle, including a new species, M. nana

Preliminary studies showed that lufenuron inhibits chitin synthesis, a dermatophyte cell wall constituent, and may be effective in the treatment of dermatophytosis. Our purpose was to evaluate the efficacy of lufenuron in the treatment of feline dermatophytosis. Forty-six cats (Persians and mixed-breed cats from 1-month to 4-years old) naturally infected with Microsporum canis were included in this study. Fifteen cats were treated isolated in cages in the veterinary hospital and 31 were treated in their home environment (some with access to the outdoors). Dermatophyte skin lesions were seen in 29 animals while 17 other cats were asymptomatic carriers. Wood's lamp, direct microscopic examination of hairs, fungal culture and skin biopsies were used for the diagnosis. Affected cats and all in-contact animals received lufenuron at a dose of 120 mg/kg every 21 days for four treatments. Of the 29 symptomatic cats treated with lufenuron, 70% recovered within 21 days and 28% within 42 days of initiation of therapy. One cat had only partial recovery and another was euthanized. Negative fungal culture was recorded only after the fourth dose of lufenuron in 98% of affected cats and 100% of asymptomatic carriers. There was no difference in clinical response to lufenuron between the cats treated in their home environment and those treated in the veterinary hospital. Side effects were not observed, thus the drug proved to be safe and effective for the treatment of dermatophytosis.
Funding: Novartis.     

Development of an enzyme-linked immunosorbant assay (ELISA) for the serodiagnosis of canine dermatophytosis caused by Microsporum canis

Abstract In dogs, dermatophytosis should be considered in any case of alopecic, papular or pustular lesion. The aim of this study was to develop an enzyme-linked immunosorbant assay (ELISA) as an aid in the diagnosis of canine dermatophytosis. The antigen used was a whole fungal extract obtained from an isolate of Microsporum canis cultured on a liquid medium from the parasitized hair of a cat with patches of alopecia. To assess the ELISA performances, sera from 18 dogs with dermatophytosis caused by M. canis (group A, n = 18), 20 dogs with skin diseases other than dermatophytosis and 22 healthy dogs (group B, n = 42) were tested. Four further animals were tested: three with dermatophytosis caused by M. gypseum and one by T. mentagrophytes. A significant difference (P < 0.01, Wilcoxon's test, w = 364) was found between IgG-specific levels of sera of recently M. canis-infected dogs (infection < 15 days) and controls (although three dogs had negative titres at this stage). A highly significant difference (P < 0.001, w = 462) was noted between controls and dogs with infection of longer duration (> 30 days). All dogs had positive titres at this stage. A highly significant correlation (P < 0.001, Spearman's test, rho = 0.86) between duration of infection and IgG concentration was noted. The test has good sensitivity (83.3%) and high specificity (95.2%) but some dogs retained positive titres after elimination of infection. The sensitivity is higher than that of direct microscopic hair examination and similar to that of fungal culture with DTM (dermatophyte test medium).     

Efficacy of pre-treatment with lufenuron for the prevention of Microsporum canis infection in a feline direct topical challenge model

Oral lufenuron is reportedly an effective treatment for some cats with dermatophytosis. The purpose of this study was to determine if lufenuron, when used as a pre-treatment prior to challenge exposure, would be protective against the development of infection after the direct topical application of fungal macrocondia (Microsporum canis spores). Three groups (n = 6/group) of juvenile cats were treated with either monthly oral lufenuron (30 or 133 mg/kg) or placebo. After 2 months of treatment, kittens were challenged using 10(5)Microsporum canis spores applied to the skin under occlusion. Cats were examined weekly and the following data collected: Wood's lamp examination; scoring for scale/crust, erythema and induration; lesion size; and the development of satellite lesions. Fungal cultures were performed bi-weekly. All cats became infected; the infections progressed, and then regressed, in a similar fashion in all groups. There were no consistent statistically significant differences in weekly infection scores between treated and untreated cats throughout the study. Treated cats did not recover faster than untreated cats. We conclude that oral lufenuron at the dosing schedule and conditions used in this study did not prevent dermatophytosis or alter the course of infection by direct topical challenge.     

Dermatophytosis caused by Trichophyton mentagrophytes in the southern chamois (Rupicapra pyrenaica) in the Eastern Pyrenees

Two free-ranging southern chamois (Rupicapra pyrenaica) - one 4-year-old male and one 3-year-old male - were diagnosed with clinical dermatophytosis in the French and Spanish Eastern Pyrenees respectively. Skin samples were collected for microbiological studies, Trichophyton mentagrophytes being isolated and identified in both animals. The first chamois was found dead at the base of a cliff, and presented with alopecia and scaling on the dorsum and left forelimb. The second chamois showed grey-yellow, rough to raised scaling and crusting skin lesions at the base of the horns, around the eyes, dorsum of the nose, sternum, tail and limbs. Histological examination was carried out only on the second animal. The main lesions were orthokeratotic hyperkeratosis with focal parakeratosis, irregular to papillary epidermal hyperplasia, intracorneal neutrophilic pustules, perivascular to diffuse dermatitis with neutrophilic folliculitis and furunculosis. In those follicles with folliculitis and/or furunculosis, fungal hyphae and arthrospores associated with the follicular keratin and hair shafts were seen.     

Use of lufenuron for treating fungal infections of dogs and cats: 297 cases (1997-1999)

OBJECTIVE: To evaluate use of lufenuron for treating cutaneous fungal infections in dogs and cats. DESIGN: Retrospective study. ANIMALS: 156 dogs and 201 cats with dermatophytosis or superficial dermatomycoses. PROCEDURE: Medical records were reviewed for dogs and cats that had been treated for dermatophytosis or other fungal infections by administration of lufenuron and 18 dogs and 42 cats that were not treated and served as a control group. RESULTS: Dogs were treated once by oral administration of lufenuron tablets at doses ranging from 54.2 to 68.3 mg/kg (24.6 to 31.0 mg/lb) of body weight. Samples of skin, scrapings, and hair were obtained daily from 14 dogs with dermatophytosis; mean durations from time of treatment to time of negative fungal culture results and resolution of gross lesions were 14.5 and 20.75 days, respectively. In all treated dogs, gross lesions resolved within approximately 21 days. Cats were treated once by oral administration of lufenuron suspension in doses ranging from 51.2 to 266 mg/kg (23.3 to 120.9 mg/lb). Samples were obtained daily from 23 cats; mean durations from time of treatment to time of negative fungal culture results and resolution of gross lesions were 8.3 and 12 days, respectively. Time to resolution of lesions in most untreated control animals was approximately 90 days. Adverse effects of treatment were not detected. CONCLUSIONS AND CLINICAL RELEVANCE: Results of this study suggest that lufenuron provides an effective, convenient, and rapid method for treating fungal infections in dogs and cats.     

Dermal mass aspirate from a Persian cat

A 1-year-old spayed female Persian cat with alopecia and weight loss had numerous variably ulcerated dermal nodules. Cytologic examination of an aspirate of one of the nodules revealed pyogranulomatous inflammation along with septate hyphae and basophilic round bodies, 0.5–1.0 μm in diameter, surrounded by a thin clear halo (arthrospores). The cytologic diagnosis was dermatophytic pseudomycetoma. Histologically, there were dermal granulomas containing poorly staining, septate hyphae with bulbous spores embedded within abundant amorphous eosinophilic material (Splendore-Hoeppli reaction), and the histologic diagnosis was pseudomycetoma-associated chronic multifocal severe granulomatous dermatitis with lymphocytic perifolliculitis and furunculosis. Microsporum canis was cultured from the lesion. Pseudomycetomas are distinguished from fungal mycetomas, or eumycotic mycetomas, by the findings of multiple lesions, lack of a history of skin trauma, an association with dermatophytes, most commonly Microsporum canis , and, histologically, lack of true cement material and a more abundant Splendore-Hoeppli reaction in pseudomycetomas. Additionally, pseudomycetomas differ from dermatophytosis, in which lesions are restricted to epidermal structures. Persian cats have a high incidence of pseudomycetoma formation, suggesting a heritable predisposition. The prognosis is fair with systemic antifungal therapy. When examining cytologic specimens from Persian cats with single or multiple dermal nodules, especially if pyogranulomatous inflammation is present, a diagnosis of pseudomycetoma should be suspected and is warranted if arthrospores and refractile septate hyphae are present.     

Chronic dermatophytosis due to Microsporum persicolor infection in three dogs

Microsporum persicolor, a rare zoophilic dermatophyte, was isolated from three dogs with skin disease of between three and five years duration. Skin lesions consisted of scaling with minimal alopecia or erythema. Severe inflammatory changes were not observed clinically and pruritus was absent or mild. The face was affected in all three cases and more widespread lesions were found in two. The diagnosis of dermatophytosis was confirmed in each case by the demonstration of fungal hyphae in the epidermal stratum corneum on examination of skin biopsies. However, hair shaft invasion was not observed in either skin scrapings or histological sections. Of the three dogs, one partially improved following repeated courses of treatment, a second completely recovered with 11 weeks of combined topical and systemic therapy. Response to therapy could not be assessed in the remaining case.     

Mycologic disorders of the skin

Cutaneous tissue can become infected when fungal organisms contaminate or colonize the epidermal surface or hair follicles. The skin can be a portal of entry for fungal infection when the epithelial barrier is breached or it can be a site for disseminated, systemic fungal disease. The two most common cutaneous fungal infections in small animals are dermatophytosis and Malassezia dermatitis. Dermatophytosis is a superficial cutaneous infection with one or more of the fungal species in the keratinophilic genera Microsporum, Trichophyton, or Epidermophyton. Malassezia pachydermatis is a nonlipid dependent fungal species that is a normal commensal inhabitant of the skin and external ear canal in dogs and cats. Malassezia pachydermatis is the most common cause of Malassezia dermatitis. The diagnosis and treatment of these cutaneous fungal infections will be discussed.     

Dermatophytes in clinically healthy dogs and cats

The hair and skin of 300 clinically healthy animals, 268 dogs and 32 cats, were examined mycologically. The method described by Mariat and Tapia (1966) was used for the examination, along with square pieces of the fitted carpet Kovral. The dermatophytes were isolated in 12 samples, all from the material taken from dogs. Trichophyton mentagrophytes was isolated six times, Microsporum canis four times, Trichophyton gallinae once, Trichophyton rubrum once. The origin of the dermatophyte Trichophyton gallinae, found in a village dog, was not determined. In one case of occurrence of the dermatophyte Trichophyton mentagrophytes in a dog the dermatophyte was probably transmitted from man to the dog. Microsporum canis was not proved to be the most frequent dermatophyte in dogs or cats in this country.     

Generalized Microsporum canis dermatophytosis in six Yorkshire terrier dogs

Six Yorkshire terrier dogs with generalized, chronic dermatophytosis caused by Microsporum canis were seen over a 3-year period. Specific tests showed that they also had concurrent leishmaniosis (four cases), leishmaniosis and ehrlichiosis (one case) or diabetes mellitus (one case). Although specific therapy for these infectious diseases was instituted and the dogs were treated systemically and topically with appropriate antifungal drugs, only partial clinical resolution of the dermatophytosis was achieved. M. canis infection resolved in the dog with diabetes mellitus after stabilizing the diabetes mellitus. Although immunological studies were not performed in these cases, it is theorized that the immune disregulation caused by leishmaniosis, ehrlichiosis or diabetes mellitus may have favoured generalization of the infection and prevented favourable responses to appropriate treatment of the M. canis infection.     

Dermatophytosis due to Microsporum persicolor (13 cases) or Microsporum gypseum (20 cases) in dogs

A retrospective study of 20 cases of dermatophytosis due to Microsporum gypseum and 13 cases due to Microsporum persicolor seen over an 8-year period is reported. These skin diseases are rare (1.3% of our canine case load) and pleomorphic, from localized erythematous and squamous or suppurative lesions (kerions) to extensive or generalized erythematous, alopecic, scaling, crusting and eventually papular and pustular dermatoses. Such dermatophytoses are diagnosed by fungal culture, and in some instances rapidly by dermatohistopathology with periodic acid-Schiff staining (3/3 cases of Microsporum gypseum infection and 5/7 cases of Microsporum persicolor infection). Therapy with topical and/or systemic azole derivatives (topical enilconazole, miconazole, econazole and systemic ketoconazole, respectively) was successful in all cases, with only two relapses, which were easily controlled.     

Efficacy of itraconazole as a combined continuous/pulse therapy in feline dermatophytosis: preliminary results in nine cases

This study evaluated the efficacy of itraconazole as a combined continuous/pulse therapy for feline dermatophytosis. Nine cats with dermatophytosis caused by Microsporum canis were treated with itraconazole at 10 mg kg(-1) orally once daily for 28 days and then on an alternate week regimen (1 week off, 1 week on) at the same dosage. Cats were re-evaluated by physical examination and fungal culture at days 28, 42, 56 and 70 if necessary. Treatment was stopped when two consecutive negative fungal cultures were obtained. Eight cats were cured after 56 days, with two negative cultures obtained at days 28 and 42. In one case, a positive culture was obtained at day 28, but negative cultures were achieved at days 42 and 56. This protocol appears to be effective in the treatment of feline dermatophytosis, although these preliminary results should be confirmed by a controlled study.     

Dermatophytosis and papular eosinophilic/mastocytic dermatitis (urticaria pigmentosa-like dermatitis) in three Devon Rex cats

PRESENTING SIGNS: Three Devon Rex cats were presented with multiple erythematous papules, occasionally associated with crusting and hyperpigmentation, with a linear distribution on the head, neck, chest and abdomen. One cat also had multifocal alopecia with hyperpigmentation on the dorsum. DIAGNOSIS AND TREATMENT: Clinical and histopathological features were suggestive of papular eosinophilic/mastocytic dermatitis (urticaria pigmentosa-like dermatitis). In all cases, dermatophytosis was diagnosed: in cases 1 and 2 there was histopathological evidence of dermatophytosis, while fungal culture was positive for Microsporum canis in cases 2 and 3. In all cats, lesions disappeared following antifungal treatment. CLINICAL SIGNIFICANCE: Papular eosinophilic/mastocytic dermatitis in Devon Rex cats may represent either an atypical presentation of dermatophytosis or a clinical and histological reaction pattern to various diseases, including dermatophytosis and allergic diseases. Clinical differentiation is crucial as there are important implications regarding treatment and, in particular, the use of glucocorticoids, which are contraindicated in cases of dermatophytosis.     

Isolation of Microsporum canis from the hair coat of pet dogs and cats belonging to owners diagnosed with M. canis tinea corporis

Microsporum canis has been frequently isolated from human cases of tinea capitis and tinea corporis. The infection may be acquired from infected animals with cutaneous lesions but also from asymptomatic carriers or from the environment. As asymptomatic M. canis carriers are considered to be a critical factor in the epidemiology of dermatophytosis in humans, this study investigated the relationship between the presence of dermatophytes on the hair coats of dogs and cats without cutaneous lesions and the occurrence of the disease in their respective owners. A total of 136 dogs and 248 cats were sampled from January 1999 to January 2005. Seventy-eight animals (22 dogs and 56 cats) belonged to individuals affected by tinea corporis caused by M. canis and 306 (114 dogs and 192 cats) to individuals without dermatophytosis. Age, sex, breed, habitat and season were recorded for each animal and examined as potential risk factors. Dermatophytes were isolated from 20.5% of the dogs and 28.2% of the cats. Microsporum canis was isolated from 36.4% of dogs cohabiting with owners diagnosed with tinea corporis but it was never isolated from dogs whose owners had no lesions. By contrast, M. canis was isolated from 53.6% of cats cohabiting with owners diagnosed with tinea corporis and from 14.6% of cats whose owners had no signs of the disease. These results clearly indicate that both cats and dogs should be considered as a major source of pathogenic dermatophytes for humans even when they do not present clinical signs of dermatophytosis.     

Terbinafine hydrochloride treatment of Microsporum canis experimentally-induced ringworm in cats

Cats represent the most important source of Microsporum canis infection to people. Terbinafine hydrochloride is commonly used in the treatment of microsporosis. Its fungicidal action permits short period of treatment. It was our objective to evaluate the effectiveness of this drug in treatment of microsporosis in cats. We treated nine experimentally M. canis infected cats with terbinafine at a dose of 10-20mg/kg SID (low-dose group, LDG), nine cats with 30-40mg/kg SID (high-dose group, HDG), and nine cats were left untreated (control group, CG). The drug's levels in cats' plasma and hair were measured by a reversed-phase high performance liquid chromatographic method (RP-HPLC) and the cats' cure was followed by Wood's lamp illumination, microscopic exam and fungal culture. We showed no difference between the clinical course in CG and LDG, but HDG were significantly differentiated from both other groups. Terbinafine levels in plasma at 120 days of treatment were not statistically different among LDG (4.13 microg/l) and HDG (5.48 microg/l), but levels in hair of LDG (1.24 microg/l) and HDG (3.62 microg/l) were significantly different. Terbinafine can be used for the treatment of microsporosis in cats in the dose of 30-40mg/kg SID.     

A case of Trichophyton mentagrophytes infection in a fennec fox (Vulpes zerda)

A 2‐year‐old male fennec fox presented with a 4 month history of nonpruritic, crusty skin lesions on the forehead, the pinnae and the tail tip. Initial investigations, including routine haematology, biochemistry profile, multiple skin scrapings, trichoscopic examination, Wood’s lamp examination and fungal culture, failed to reveal any abnormalities. Histopathological examination of a first set of skin biopsies showed an interface dermatitis pattern, with lymphocyte infiltration in the basal layer, a significant lymphocytic exocytosis and occasional apoptotic basal epidermal keratinocytes; periodic acid Schiff stain did not reveal any fungal elements. On further biopsies, there was a pustular neutrophilic dermatitis, with numerous crusts containing high numbers of arthrospores and fungal hyphae. Trichophyton mentagrophytes infection was confirmed on fungal culture and PCR. The fennec fox received oral itraconazole (5 mg/kg once daily for 6 weeks) combined with a miconazole and chlorhexidine shampoo applied on affected areas once weekly, followed with an enilconazole dip. The fox improved dramatically, and a fungal culture performed at 6 weeks was negative. Unfortunately, a few days later the fennec fox developed anorexia, icterus and died. To the authors’ knowledge, this is the first report of Trichophyton infection in a fennec fox and, although a postmortem examination was not performed, this is possibly the first report of fatal acute liver failure associated with itraconazole in a canid.     

Dermatophytes from skin lesions of domestic animals in Nsukka,Enugu State,Nigeria

Background – Dermatophytes are well‐recognized cutaneous fungi with public health implications. In Nigeria, several studies have been carried out on dermatophytosis in humans; however, data on dermatophytes in animals are lacking. Objectives – This study was conducted to determine the occurrence and species of dermatophytes in skin lesions in domestic animals in Nsukka Agricultural Zone of Enugu State, Nigeria. Animals – Forty‐six domestic animals (dogs, goats, sheep and pigs) presented for sale in the local markets in the study area and with suspected lesions of dermatophytosis were used for the study. Methods – Plucked hairs and epidermal scales from the skin lesions of affected animals were inoculated on Sabouraud dextrose agar slants containing 0.05 mg/mL of chloramphenicol and 0.5 mg/mL of cycloheximide. Inoculated slants were incubated at room temperature (27°C) for up to 4 weeks and examined at 2–3 day intervals for fungal growth. Laboratory identification of the fungal isolates was based on their colonial, microscopic and biochemical characteristics. Results – Of the 46 animals with suspected lesions of dermatophytosis, six (13.0%) were positive for a dermatophyte, and the following dermatophytes were identified: Microsporum gypseum, two of 12 sheep; Microsporum audouinii, one of 16 dogs; Trichophyton mentagrophytes, one of 16 dogs and one of 12 sheep; and Trichophyton schoenleinii, one of 13 goats. Conclusions and clinical importance – Anthropophilic dermatophytes are among the fungal agents associated with dermatophytosis in animals in Nsukka Agricultural Zone. These dermatophytes could constitute health risks to humans in contact with the animals.     

Environmental detection of Microsporum canis arthrospores in the households of infected cats and dogs

Microsporum canis is the dermatophyte most frequently recovered from canine and feline ringworm cases. The household environment can be contaminated both by symptomatic animals and through asymptomatic M canis carriage, resulting in a potential human health risk. The load of M canis arthrospores was determined in households harbouring infected pets, in order to evaluate the infectivity of the animals versus the environment. The environments inhabited by 30 symptomatic animals (21 cats and 9 dogs) infected by M canis were examined by sampling both surfaces and indoor air. The surfaces were examined by means of contact plates; the air sampling was performed with a Sas super-100 AIR SAMPLER (PBI, Italy). Environmental contamination was detected in all households with cats, while only four out of nine houses harbouring dogs were found positive. The frequence of isolation in each sampling, and the results in terms of colony forming units per plate in the different houses appeared to be quite homogeneous. Heavily infected environments harboured kittens only. Infected owners were observed in eight households, in all of which at least one infected cat was present. No history of human dermatophytosis in households harbouring dogs was found. On the basis of our results, infected cats appear to cause substantial environmental contamination, and provoke a substantial presence of viable airborne fungal elements. Dogs seem to be of lower importance in the spread of M CANIS: they contaminated surfaces, but they never contaminated the air. The results of this study confirm the potential leading role of the feline species in the environmental spread of M canis.