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1.
Malassezia spp. dermatitis, a rare disorder in cats, has previously been associated with immune suppression and internal malignancies. This study evaluates the presence and importance of Malassezia spp. in feline biopsy specimens submitted for histopathological examination. Five hundred and fifty haematoxylin and eosin-stained skin biopsy specimens received for histopathological examination between January 1999 and November 2000 were reviewed. Fifteen (2.7%) submissions contained Malassezia organisms in the stratum corneum of the epidermis or follicular infundibulum. Eleven of 15 cats presented with an acute onset of multifocal to generalized skin lesions. All 11 cats were euthanized or died within 2 months of the onset of clinical signs. Seven cats had dermatopathological changes and clinical signs supportive of paraneoplastic alopecia, and three cats had an interface dermatitis suggestive of erythema multiforme or thymoma-associated dermatosis. Histopathological changes were nonspecific in one cat that was euthanized 2 weeks following onset of severe pruritus and alopecia. In three cats, Malassezia spp. were found in localized sites (two chin, one footpads) and appeared inconsequential to their overall health status. One cat had Malassezia spp. in association with cutaneous demodicosis. These findings suggest that Malassezia yeast in dermatopathological specimens from multifocal or generalized lesions should prompt a thorough clinical work-up for internal neoplasia.  相似文献   

2.
Symmetrical alopecia, scaling and hepatitis in a rabbit   总被引：2，自引：1，他引：1  
A 5-year-old rabbit with inappetence, symmetrical alopecia and skin lesions was examined. No mites or Malassezia were found in skin scrapings and tape impressions and dermatophyte culture was negative. Trial therapy with ivermectin did not reduce skin lesion severity, and euthanasia was performed because of anorexia after 1 month. Histopathology of the skin showed hyperkeratosis, lymphocytic exocytosis, cell-poor interface dermatitis (lymphocytic infiltration and apoptotic cells in basal layer of epidermis), absence of sebaceous glands and lymphocytic mural folliculitis comparable to sebaceous adenitis and thymoma-associated exfoliative dermatitis previously described in rabbits. The liver exhibited an interface hepatitis, comparable to autoimmune hepatitis in man. The occurrence of morphological similarities to exfoliative dermatitis and sebaceous adenitis in rabbits, in association with an autoimmune hepatitis, has not been described before.  相似文献   

3.
Abstract Epidermal hyperplasia is one of the major histopathological features seen in dogs with Malassezia dermatitis. The aim of this study was to investigate the effects of extracts and culture supernatants from Malassezia pachydermatis on the proliferation of canine keratinocytes. Keratinocyte cultures were established from normal dog skin, and cell monolayers were co-cultured with Malassezia extracts (prepared either with or without protease inhibitors) and supernatants derived from organisms grown in liquid culture. The proliferation of keratinocytes was measured using a colourimetric assay. Neither the culture supernatants nor the Malassezia extracts had significant effects on the proliferation rate of canine keratinocytes, regardless of whether protease inhibitors were present or not. The results indicate that the epidermal hyperplasia seen in Malassezia dermatitis is unlikely to be caused directly by secretion of products from the organism.  相似文献   

4.
OBJECTIVE: To investigate the potential cell-mediated immune response of atopic dogs to the yeast Malassezia pachydermatis and to correlate it with the type-1 hypersensitivity (humoral) response of the same population of dogs. ANIMALS: 16 clinically normal dogs, 15 atopic dogs with Malassezia dermatitis, 5 atopic dogs with Malassezia otitis, and 7 atopic control (ie, without Malassezia dermatitis or otitis) dogs. PROCEDURE: A crude extract of M pachydermatis was extracted for use as an intradermal allergy testing reagent and for stimulation of isolated peripheral blood mononuclear cells in vitro. Flow cytometry was also used to assess cell surface antigenic determinants (CD3, CD4, CD8, CD14, CD21, CD45RA, surface immunoglobulin) on peripheral blood mononuclear cells. RESULTS: Atopic dogs with cytologic evidence of Malassezia dermatitis had an increased lymphocyte blastogenic response to crude M pachydermatis extract, compared with clinically normal dogs and dogs with Malassezia otitis. Atopic control dogs did not differ significantly in their responses from atopic dogs with Malassezia dermatitis or otitis. A significant correlation was not found between the lymphocyte blastogenic response and the type-1 hypersensitivity response to M pachydermatis within any of the groups. CONCLUSIONS AND CLINICAL RELEVANCE: Cell-mediated and humoral reactivities to M pachydermatis contribute to the pathogenesis of atopic dermatitis in dogs but are not directly correlated. Modification of the dysregulated immune response toward M pachydermatis may assist in the reduction of pathologic changes associated with an atopic dermatitis phenotype in dogs.  相似文献   

5.
A recent study demonstrated that 47.7% of dogs with Malassezia dermatitis had a subepidermal linear alignment of mast cells (SLAM). A retrospective histopathological study was conducted on 419 canine skin biopsies to determine if a SLAM was present in other inflammatory diseases. Cases examined included dogs with demodicosis, sarcoptic mange, dermatophytosis, pemphigus foliaceus, pemphigus erythematosus, discoid lupus erythematosus, systemic lupus erythematosus, erythema multiforme, dermatomyositis, staphylococcal pyoderma, primary seborrhea, arthropod bites, contact hypersensitivity, flea bite hypersensitivity, atopy, and food hypersensitivity. Three cases (3/419, 0.7%) were identified with SLAM. The diagnoses for these cases were atopy (1/23, 4%) with a secondary bacterial folliculitis (1/136, 0.7%), pemphigus erythematosus (1/18, 6%), and discoid lupus erythematosus (1/16, 6%). Based on this study, SLAM is significantly more common in Malassezia dermatitis than in other inflammatory diseases.  相似文献   

6.
A 5-year-old rabbit with generalized scaling is presented. Multiple skin scrapings and acetate tape impressions were negative for mites and Malassezia. Culture for dermatophytes was also negative. Skin biopsies showed similarities with sebaceous adenitis described in rabbits (absence of sebaceous glands, perifollicular lymphocytic infiltrate at the level of the absent sebaceous glands, lymphocytic mural folliculitis, interface dermatitis). The owners refused any treatment and 2 months later the rabbit was euthanized due to anorexia. At necropsy a mass was found in the anterior mediastinum. Histopathology confirmed a diagnosis of thymoma. A possible paraneoplastic skin disease was suspected, based on similarities with thymoma-associated exfoliative dermatitis in cats.  相似文献   

7.
Facial dermatitis in cats is a poorly understood clinical problem observed in Persian and Himalayan cats. This report describes three cases of idiopathic facial dermatitis in the Persian cat controlled with cyclosporine. The syndrome was observed in a 5-year-old intact female, a 1.5-year-old intact male, and a 3-year-old neutered male Persian cat. The lesions developed over 2 years, 2 months and 18 months, respectively. Cutaneous lesions were mainly localized to the face. A black patchy waxy exudate matted the hair, especially on the chin. Mild crusts and black exudate were also noted on the vulvar folds in one case and on the ventral aspect of the neck in another case. Erythematous, ceruminous otitis was observed in one case. The histopathological findings were exactly the same for all three cases and compatible with idiopathic facial dermatitis of the Persian cat, or eventually an allergic reaction. All cases were managed with cyclosporine (Neoral® 6–7 mg/kg/day). Lesions were completely controlled after 4–6 weeks. During a 6-month follow-up for two cases, the lesions seemed to be more resistant to therapy. For these two cats, secondary infections with cocci and Malassezia occasionally occurred. No adverse reactions were observed in our three treated cats.
Funding: Self-funded.  相似文献   

8.
Isolates of Malassezia pachydermatis from healthy dog skin and from dogs with atopic dermatitis were molecularly characterized using internal spacer 1 (IGS1) region analyses, and their phospholipase A2 activity and pH growth profiles were then characterized in vitro. The percentage of isolates from healthy dogs that had the following IGS1 subtypes (isotype, %) were as follows: 1A, 6%; 1B, 27%; 1C, 11%; 2A, 6%; 2B, 6%; 3A, 11%; 3C, 3%; and 3D, 24%. In contrast, 9% of isolates from dogs with atopic dermatitis were isotype IB and 91% were isotype 3D, indicating that isolates of subtype 3D were the most prevalent in dogs with atopic dermatitis. Production of phospholipase A2 was statistically higher in isolates of subtype 3D than in the other subtypes. The subtype 3D isolates showed enhanced growth on alkaline medium compared with non-3D subtype isolates. The main clinical sign of canine Malassezia dermatitis is waxy exudates on the skin, which predispose the patient to development of a yeast overgrowth of the subtype 3D. Increased phospholipase A2 production may be involved in the inflammatory process associated with Malassezia dermatitis.  相似文献   

9.
Two recent case reports described a congenital keratinization defect (congenital follicular parakeratosis; CFP) in Rottweiler and Siberian Husky dogs. Skin biopsy specimens revealed marked parakeratosis targeting the hair follicle and numerous intracorneal vacuoles. A retrospective histopathological study was conducted on skin biopsy specimens from 111 dogs with diseases associated with parakeratotic hyperkeratosis to determine whether intracorneal vacuoles were present. Additional criteria evaluated were the size and location of the vacuoles and the degree of parakeratosis. Cases examined included dogs with primary idiopathic seborrhoea, necrolytic migratory erythema (NME), Malassezia dermatitis, zinc-responsive dermatosis, hereditary nasal hyperkeratosis of Labrador Retriever dogs, thallotoxicosis and CFP. Thirty-seven cases (37/111, 33%) had intracorneal vacuoles, including nine cases of primary idiopathic seborrhoea (9/29, 31%), 10 cases of NME (10/18, 56%), five cases of Malassezia dermatitis (5/19, 26%), five cases of zinc-responsive dermatosis (5/36, 14%), five cases of hereditary nasal hyperkeratosis (5/5, 100%) and three cases of CFP (3/3, 100%). If present, intracorneal vacuoles were found throughout all layers of the parakeratin. The sizes of intracorneal vacuoles varied among diseases, but large (> 5 microm) vacuoles only were present in CFP. Biopsies with a larger degree of parakeratosis were significantly more likely to have intracorneal vacuoles (P = < 0.001). Based on this study, intracorneal vacuoles are a common finding in many parakeratotic skin diseases of the dog, but large (> 5 microm) vacuoles are found only in CFP.  相似文献   

10.
The prevalence of cutaneous Malassezia spp was evaluated in a semiquantitative fashion at 3 sites on 98 dogs examined because of various dermatoses. Thirty (10.2%) of the sites and 19 (19.4%) of the dogs had Malassezia spp amounts higher than that found on grossly normal skin. The prevalence of higher than normal amounts did not correlate significantly with sample site, sex, or age. The factors associated with an increased prevalence of increased Malassezia spp counts were seborrheic dermatitis, recent antibiotic treatment, and breed.  相似文献   

11.
Histopathology submissions from 28 goats with dermatological disease were identified in an archival search of pathology files. Microscopic sections of skin biopsy specimens were examined for the presence of Malassezia spp. organisms. Six cases with many Malassezia yeasts were identified histopathologically. Based on the extent of clinical disease, three cases were regarded as localized and three were generalized infections. Clinical findings included alopecia with dry seborrhoea (four cases), greasy seborrhoea (one case), and no clinical findings specific to localized Malassezia infection when concurrent bacterial infection was present (one case). Mild pruritus was reported in two cases of generalized infection. No breed predilection was apparent. Three cases were male and three were female. Malassezia dermatitis occurred in goats from 10 months to 13 years of age. Three of six cases had concurrent bacterial infection. Skin lesions resolved following topical antifungal therapy in the two goats that were treated. Histopathological findings in all cases were severe follicular and epidermal orthokeratotic hyperkeratosis with minimal epithelial change and mild superficial perivascular to interstitial nonsuppurative inflammation. Numerous budding yeasts were visible within the stratum corneum of all cases; however, Malassezia was not isolated in the three cases in which culture was attempted. Based upon these findings, the authors suggest that the diagnosis Malassezia dermatitis in goats is most likely to be made by cytological examination of skin impressions or by examination of skin biopsy samples.  相似文献   

12.
Abstract Macroscopic and cytological aspects of anal sac content were evaluated in 40 normal dogs and 10 dogs each with pyoderma, Malassezia dermatitis associated with atopic dermatitis and uncomplicated atopic dermatitis. Bacteria isolated from anal sacs were compared with those from abdominal skin and hair in 20 normal dogs and 10 dogs with pyoderma. There was no difference between the groups in anal sac dimension, or in the colour, consistency or presence of granules in their content. Extracellular bacteria were found in higher numbers in diseased animals, whereas intracellular bacteria were observed in 40% of dogs with pyoderma and in only 2.5% of normal dogs. Malassezia spp. were present in 15.7% of dogs, with no difference between groups. Neutrophils were observed in 12.5% of normal dogs, 30% of dogs with Malassezia dermatitis with underlying atopic dermatitis and in 70 and 80% of dogs with pyoderma and uncomplicated atopic dermatitis, respectively. Seven bacterial species were isolated from anal sacs, with no difference between normal dogs and dogs with pyoderma. In five normal animals and in four dogs with pyoderma the same bacterial strains were isolated from anal sacs and from abdominal skin and hair.  相似文献   

13.
Significant numbers of humans with atopic dermatitis develop Malassezia-specific IgE. Immediate skin-test reactivity to Malassezia has been demonstrated in atopic dogs. The aim of this study was to compare the serum IgG and IgE response to Malassezia in atopic dogs with and without clinical evidence of Malassezia dermatitis and/or otitis, nonatopic dogs with clinical evidence of Malassezia dermatitis and/or otitis and healthy dogs. Cytology was used to diagnose clinically significant Malassezia dermatitis and otitis. Contact plate cultures confirmed the validity of this technique. Reproducible enzyme-linked immunosorbent assays for Malassezia-specific IgG and IgE in canine serum were established. Atopic dogs had significantly higher serum IgG and IgE levels than either healthy dogs or nonatopic dogs with clinical evidence of Malassezia dermatitis and/or otitis. There was no significant difference in IgG and IgE levels between atopic dogs with and without clinical evidence of Malassezia dermatitis and/or otitis. The implications of these findings in the pathogenesis and management of canine atopic dermatitis are discussed.  相似文献   

14.
The purpose of this randomized, single blinded clinical trial was to evaluate cytologically and clinically the efficacy of oral cephalexin alone and its combination with terbinafine or ketoconazole for the treatment of Malassezia dermatitis in dogs. Twenty-two client-owned dogs with Malassezia dermatitis completed the 3-week study. All received cephalexin (generic, 250 mg or 500 mg) at 22-30 mg kg(-1) twice daily. Eight dogs received terbinafine at 30 mg kg(-1) once daily and seven dogs received ketoconazole (generic, 200 mg) at 5-10 mg kg(-1) twice daily. The remaining seven dogs received cephalexin alone. At week 0 (visit 1) and week 3 (visit 2), mean yeast counts were determined from three affected areas using tape-strip cytology, a clinical index score (CIS) was assigned to the affected areas, and owners evaluated pruritus using a visual analogue scale. All groups showed reduction in mean yeast counts, CIS and pruritus. There was an 86.8%, 80.2% and 28.8% reduction in mean yeast counts from visit 1 to visit 2 for the terbinafine, ketoconazole and cephalexin-only groups, respectively. However, within treatment group comparisons a significant reduction in mean yeast count was only evident for the terbinafine (P < 0.002) and ketoconazole (P < 0.01) groups. Pruritus reduction was only significant for the terbinafine group. These preliminary results suggest that terbinafine should be further assessed for the treatment of canine Malassezia dermatitis.  相似文献   

15.
This double-blinded noninferiority clinical trial evaluated the use of oral fluconazole for the treatment of Malassezia dermatitis in dogs by comparing it with use of an accepted therapeutic agent, ketoconazole. Dogs presenting with Malassezia dermatitis were treated with either fluconazole or ketoconazole in addition to cephalexin for concurrent bacterial dermatitis. Statistically significant improvements in cytologic yeast count, clinical signs associated with Malassezia dermatitis, and pruritus were seen with both antifungal treatments. There was no statistical difference between the treatments with regard to the magnitude of reduction in these parameters. These results suggest that fluconazole is at least as effective as ketoconazole for the treatment of dogs with Malassezia dermatitis.  相似文献   

16.
OBJECTIVE: To investigate the direct interaction between canine keratinocytes and live Malassezia pachydermatis and thereby determine the role of these organisms in the pathogenesis of epidermal hyperplasia associated with Malassezia dermatitis in dogs. SAMPLE POPULATION: Primary canine keratinocyte cultures established from skin samples obtained from clinically normal dogs. PROCEDURE: The proliferative response of keratinocytes co-cultured with Malassezia organisms for 1, 2, or 3 days was assessed by use of direct manual counting (to determine the number of keratinocytes in both the monolayer and the medium) and immunohistochemical staining techniques involving antibodies against proliferating cell nuclear antigen (PCNA) and another cellular proliferation marker, Ki-67. The potential cytotoxic effect of Malassezia organisms was investigated by use of an apoptosis detection kit to label keratinocytes co-cultured with M. pachydermatis that underwent apoptosis. RESULTS: No stimulatory effect of Malassezia organisms on canine keratinocyte proliferation was detected via cell counting and immunohistochemical techniques. However, there was a significant increase in dead keratinocytes in the medium with increasing numbers of Malassezia organisms in the co-culture. More apoptotic cells were observed in keratinocyte monolayers co-cultured with high numbers of M. pachydermatis than there were in monolayers cultured without Malassezia organisms, and the number increased after prolonged incubation. CONCLUSIONS AND CLINICAL RELEVANCE: M. pachydermatis did not stimulate canine keratinocyte proliferation in vitro. The results suggested that the epidermal hyperplasia observed in dogs with Malassezia dermatitis is unlikely to be caused by a direct effect of the organism on the keratinocyte cell cycle, but is likely to involve other mechanisms.  相似文献   

17.
Adhesive tape strip and dry swab sampling techniques were compared for the detection of Malassezia pachydermatis on the skin of dogs with chronic dermatitis. One hundred and four dogs were sampled by each of the techniques. Two methods, a culture method and a stain method, were used to assess the sampling techniques. By the adhesive tape strip sampling technique, M. pachydermatis was detected on 83 (80%) dogs using the culture method and on 45 (43%) dogs using the stain method. By the dry swab sampling technique, M. pachydermatis was detected on 55 (53%) dogs using the culture method and on 33 (32%) dogs using the stain method. The study showed that the adhesive tape strip sampling technique, using the culture method, detected Malassezia on the skin of significantly more dogs (P<0.001) than the same technique using the stain method and also significantly more than the dry swab sampling technique, using either the culture or stain methods. It was also shown that an adhesive tape sample could be used to transfer cells to a slide for staining and microscopy prior to being used for culturing Malassezia.  相似文献   

18.
A 6-year-old female goat was presented with a seborrhoeic dermatosis of 5 months duration. The condition developed following a severe enteritis associated with weight loss. Dermatological examination showed a generalized greasy seborrhoeic dermatosis, which spared the head and extremities of the limbs. Microscopic examination of impression smears of lesional skin revealed numerous yeasts typical of Malassezia sp. Culture on Sabouraud's dextrose agar yielded Malassezia pachydermatis growth. Histopathological examination of haematoxylin/eosin and safranin (HES) stained sections of biopsies showed mild lymphocytic superficial perivascular hyperplastic dermatitis. Numerous budding yeasts were visible both on the surface, and follicular keratin, in HES and periodic acid Schiff (PAS) stained sections. A dramatic response was observed after 1 week of a topical anti-Malassezia treatment, and the resolution of the condition was complete after 4 weeks.  相似文献   

19.
In 12 cases of lethal acrodermatitis (LAD), four sampling techniques (brush, swab, scrape and adhesive tape strip) were used to study the distribution of yeasts in various body sites and these results were compared with those from five cases of atopic dermatitis and those of 10 normal dogs. Malassezia was frequently isolated from lesional and non-lesional skin and haircoat, footpads, nails and mucous membranes from dogs with either LAD or atopic dermatitis, although, generally, more Malassezia organisms were isolated from LAD cases. In normal dogs, Malassezia was most frequently recovered from the ear canal and the perianal skin. Candida was isolated frequently from dogs with LAD, but only a single isolate of this yeast was found in the other two groups. Fungal hyphae and pseudohyphae, probably Candida albicans, could be detected in samples collected from the nails and footpads of dogs with LAD. Both Malassezia and Candida could be isolated using all four sampling techniques. The MacKenzie (toothbrush) technique and adhesive tape strip cultures proved simple methods for the semiquantitative evaluation of yeasts. The high recovery rate of Malassezia and Candida from dogs with LAD is probably related to immune dysfunction, particularly T-cell dysfunction, known to be present in these dogs. C albicans infection may in part be responsible for the pathogenic changes of the nails and footpads commonly seen in cases of LAD.  相似文献   

20.
Abstract We have previously shown that both atopic and normal dogs generate an IgG response to antigens of Malassezia pachydermatis . The aim of this study was to compare IgE responses to separated proteins of M. pachydermatis in 28 atopic dogs with Malassezia dermatitis and 22 clinically normal dogs using Western immunoblotting. Six different detection systems were evaluated in order to assess sensitivity and eliminate nonspecific binding and cross-reactivity. The protocol yielding the best results utilized a monoclonal mouse antidog IgE, an alkaline phosphatase conjugated goat antimouse IgG which had been passed through a canine IgG column 3 times, a chemiluminescent substrate and a digital imaging system. Proteins of 45, 52, 56 and 63 kDa were recognized by more than 50% of the atopic dog sera and thus represented major allergens. Only a minority of normal dogs showed faint IgE binding to these proteins. The results indicate that the majority of atopic dogs with Malassezia dermatitis have a greater IgE response than normal dogs, suggesting an IgE-mediated immune response may be clinically important in the pathogenesis of the disease.  相似文献   

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