Veterinary Dermatology

Companion animal staphylococcal isolate antibiograms were screened retrospectively to determine the frequency of methicillin‐resistant (MR) infection byStaphylococcus aureus,Staphylococcus intermedius, andStaphylococcus schleiferi. Rates of MR were:S. aureus35%,S. intermedius17%, andS. schleiferi40%. Frequency of isolation of methicillin‐resistantS. aureus(MRSA) from dogs and cats was similar, whereas methicillin‐resistantS. intermedius(MRSI) and methicillin‐resistantS. schleiferi(MRSS) were significantly more common in dogs. MRSS was more commonly associated with superficial (skin and ear canal) infections, whereas MRSA was more commonly associated with deep infections. The MR strain resistance pattern to other classes of antibiotics was also investigated. MRSA was resistant to the most classes of antibiotics, followed by MRSI, while MRSS maintained the most favourable susceptibility profile. MR staphylococci may pose a significant risk to animal and public health. Therefore, to avoid selecting for resistant strains in cases of suspected staphylococcal infection, clinicians should consider culture and susceptibility testing early in the course of treatment.

The aim of this systematic review was to evaluate the efficacy of antifungal treatments forMalasseziadermatitis in dogs and, when possible, to propose recommendation for or against their use.

Electronic searches were carried out using PubMed MEDLINE®, CABDirect and CONSULTANT database. The volumes ofAdvances in Veterinary Dermatology, the proceedings of ESVD/ECVD and AAVD/ACVD congresses were hand‐searched for studies relevant to this review. All articles and book chapters discussing treatment ofMalasseziadermatitis were scanned for additional citations. Lastly, a request was sent to the Vetderm Listserv to share recent clinical trials. The analysis evaluated study design, methodology quality, subject enrolment quality, type of interventions and outcome measures.

The searches identified 35 articles, and 14 trials that fulfilled the following selection criteria: (i)in vivoclinical trials, (ii) dogs showing clinical lesions ofMalasseziadermatitis and (iii) enrolment of at least five dogs. Among these, only eight studies fulfilled the following additional criterion: (iv) prospectivein vivoclinical trials reporting clinical and mycological outcome measures. A total number of 14 different treatment protocols included four blinded, randomized and controlled trials (quality of evidence grade A), four controlled studies lacking blinding and/or randomization (grade B), five open uncontrolled trials (grade C) and one descriptive study (grade D).

This systematic review allowed us to recommend, with good evidence, the use of only one topical treatment ofMalasseziadermatitis (2% miconazole nitrate +2% chlorhexidine, twice a week for 3 weeks) and with fair evidence the use of two systemic treatments with azole derivatives (ketoconazole, 10 mg kg⁻¹ day⁻¹and itraconazole, 5 mg kg⁻¹ day⁻¹for 3 weeks).

Abstract  Although canine atopic dermatitis (cAD) is common, few models are available. The aim of this study was to evaluate high‐IgE beagles epicutaneously sensitized to house dust mite (HDM) as a possible model for cAD. Six high‐IgE beagles were environmentally challenged with HDM using various doses and protocols. Similar challenge protocols were used in positive and negative control dogs: three dogs with naturally occurring cAD and positive intradermal skin test (IDT) to HDM and three normal dogs without history of skin disease and negative IDT to HDM. All high‐IgE beagles and all atopic dogs developed severe cutaneous lesions and pruritus after challenge. Lesions were erythematous papules and macules in contact areas such as face, ears, ventral abdomen, groin, axillae and feet. They were first visible after 6 h and increased in severity over time. No normal dog developed pruritus or lesions. Biopsies of representative lesions in the high‐IgE beagles were taken for histopathology and immunohistochemistry. There was superficial perivascular dermatitis with mononuclear infiltrates and spongiosis. Lymphocytes and eosinophils accumulated in small epidermal micro‐abscesses with hyperplasia of epidermal IgE‐bearing dendritic cells. These findings suggest that this colony of high‐IgE beagles develops a dermatitis that clinically, histopathologically and immunologically resembles the naturally occurring canine disease. It is also concluded that this modality of challenge is not irritating to normal dogs but induces flare‐ups in hypersensitive atopic dogs.

AbstractMalasseziaspp. dermatitis, a rare disorder in cats, has previously been associated with immune suppression and internal malignancies. This study evaluates the presence and importance ofMalasseziaspp. 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 containedMalasseziaorganisms 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,Malasseziaspp. were found in localized sites (two chin, one footpads) and appeared inconsequential to their overall health status. One cat hadMalasseziaspp. in association with cutaneous demodicosis. These findings suggest thatMalasseziayeast in dermatopathological specimens from multifocal or generalized lesions should prompt a thorough clinical work‐up for internal neoplasia.

A 10‐year‐old castrated male Shih Tzu presented with severe generalized pruritus. Skin scrapings revealed the presence of Sarcoptes scabiei var. canis. A Yorkshire terrier in the same household simultaneously developed pruritus due to scabies. Both dogs were treated with 300 μg/kg ivermectin, at first orally and then subcutaneously at 14 day intervals. However, live mites were still found on day 35, and the skin condition deteriorated in both dogs. These findings suggested that the S. scabiei in these dogs was clinically refractory to ivermectin. The pruritus in both dogs rapidly and completely disappeared following topical fipronil administration. This appears to be the first report of canine scabies refractory to ivermectin treatment.

A series of 18 allergic cats with multifocal Malassezia spp. overgrowth is reported: atopic dermatitis was diagnosed in 16, an adverse food reaction in another and one was euthanized 2 months after diagnosis of Malassezia overgrowth. All the cats were otherwise healthy and those tested (16 out of 18) for feline leukaemia or feline immunodeficiency virus infections were all negative. At dermatological examination, multifocal alopecia, erythema, crusting and greasy adherent brownish scales were variably distributed on all cats. Cytological examination revealed Malassezia spp. overgrowth with/without bacterial infection in facial skin (n = 11), ventral neck (n = 6), abdomen (n = 6), ear canal (n = 4), chin (n = 2), ear pinnae (n = 2), interdigital (n = 1) and claw folds skin (n = 1). Moreover, in two cats Malassezia pachydermatis was isolated in fungal cultures from lesional skin. Azoles therapy alone was prescribed in seven, azoles and antibacterial therapy in eight and azoles with both antibacterial and anti‐inflammatory therapy in three of the cats. After 3–4 weeks of treatment, substantial reduction of pruritus and skin lesions was observed in all 11 cats treated with a combined therapy and in five of seven treated solely with azoles. Malassezia spp. overgrowth may represent a secondary cutaneous problem in allergic cats particularly in those presented for dermatological examination displaying greasy adherent brownish scales. The favourable response to treatment with antifungal treatments alone suggests that, as in dogs, Malassezia spp. may be partly responsible for both pruritus and cutaneous lesions in allergic cats.

The clinical and histopathological features of 13 Persian cats which presented with chronic skin disease primarily affecting the face are described. Lesions were characterized by black material adherent to the skin and hair, accompanied by erythema and variable degrees of excoriation. Concurrent ceruminous otitis externa was observed in 7 cases. Histopathological examination of skin biopsy specimens showed marked acanthosis with crusting, hydropic degeneration and dyskeratotic basal epithelial cells, a mixed diffuse superficial inflammatory infiltrate and sebaceous hyperplasia. Malassezia pachydermatis yeasts and various bacteria were isolated from the lesions in some of the cats but in no case was antimicrobial therapy curative. The response to glucocorticoids was variable and often poor. No satisfactory therapeutic regimen could be identified and the cause of the disorder is unknown although a genetic basis is possible.

Clinical, cytological, microbial and histopathological features of feline acne were investigated in 22 cats referred or volunteered to a veterinary dermatology practice in the south‐west region of the USA. For comparison, same parameters were evaluated in five unaffected pet cats. Additionally, all cats were evaluated by immunohistochemistry (IHC) for the presence of feline calicivirus (FCV) and feline herpes virus (FHV‐1) in acne lesions. The age of onset of acne in affected cats ranged from 6 months to 14 years with a median of 4 years. The most common dermatologic lesions were comedones (73%), alopecia (68%), crusts (55%), papules (45%) and erythema (41%). Pruritus was reported in 35% of the affected cats. Cytological evidence ofMalassezia pachydermatitiswas present on 4/22 (18%) of affected cats.Microsporum caniswas isolated from a single affected cat. Bacteria were isolated from 10 of the 22 (45%) affected cats; coagulase‐positive staphylococci and alpha‐haemolytic streptococci were most common. Histopathological features included lymphoplasmacytic periductal inflammation (86%), sebaceous gland duct dilatation (73%), follicular keratosis with plugging and dilatation (59%), epitrichial gland occlusion and dilatation (32%), folliculitis (27%), pyogranulomatous sebaceous adenitis (23%) and furunculosis (23%). In one affected cat from a household with five cats, simultaneously having feline acne, FCV antigen was detected in the biopsy of the chin by IHC. Chin tissue samples from all other affected cats, as well as the five healthy cats, were negative by IHC for FCV and FHV‐1 antigens.