Sensitivity patterns to house dust mites and forage mites in atopic dogs: 150 cases

This study investigated intradermal test reactions to extracts of six species of mites in 150 dogs with atopic dermatitis. At least one positive reaction was seen in 120 animals (80%). Dermatophagoides farinae attracted the highest number of positive reactions (108 dogs, 90% of dogs and 72% of atopic dogs showing positive reactions). Positive reactions to other mites were not uncommon, with many dogs testing positive for Dermatophagoides pteronyssinus (32% of dogs tested), Acarus siro (35%), Tyrophagus putrescentiae (30%), Glycyphagus domesticus (27%) and Lepidoglyphus destructor (23%). Sensitivity to D. farinae alone occurred commonly (57% of cases), but multiple sensitivities were seen frequently with the other mites. Cases of sensitivity to only one mite were also seen: D. pteronyssinus (five cases), T. putrescentiae (one case) and G. domesticus (one case). Further studies are needed to appreciate more clearly the precise role played by the different species of mite in canine atopic dermatitis.     

Autoimmune mediated skin diseases

The clinical signs associated with non-bullous and bullous immune-mediated diseases are discussed, together with diagnostic procedures. The methods of treating, or suppressing, these autoimmune diseases are also outlined.     

Prospective study of bacterial overgrowth syndrome in eight dogs

Eight dogs with cutaneous lesions, clinical signs and cytological findings compatible with bacterial overgrowth syndrome were compared with four healthy dogs. The affected dogs were treated for 28 days with 30 mg/kg/day cephalexin. The results showed that the syndrome was a superficial cutaneous disorder characterised by marked pruritus, greasy seborrhoea, offensive odour, erythema, lichenification, hyperpigmentation, excoriations and alopecia involving principally the ventral aspect of the body, but no papules, pustules, epidermal collarettes or crusts; it was caused by overgrowths of Staphylococcus intermedius all over the body surface. Histopathological findings included a superficial, perivascular, hyperplastic and spongiotic dermatitis with a mixed inflammatory infiltrate, but no lesions suggestive of a true pyoderma. In the affected dogs, anti-staphylococcal immunoglobulin G levels were high, but anti-staphylococcal immunoglobulin E levels were low, suggesting that staphylococcal hypersensitivity is not the underlying pathogenic process. The antibiotic treatment improved the condition of all the dogs, but five of the eight had an underlying allergic skin disease.     

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.     

Therapy, control and prevention of flea allergy dermatitis in dogs and cats

This article reviews contemporary concepts underlying the design of control strategies for the management of flea allergy dermatitis in dogs and cats. The limitations of palliative symptomatic approaches are noted, as is the fundamental requirement to differentiate simple pulicosis from true hypersensitivity. In the latter case, eradication of fleas from the affected animal and its surroundings has to be an essential aim. The different biological properties offered by modern chemotherapy are defined and the range of techniques for applying active compounds to the animal and its environment described. Factors for consideration when formulating control strategies and selecting chemotherapeutic agents are discussed in the context of the complexities of the flea life-cycle, the host-parasite relationship and client concerns.     

Randomized controlled trial of the efficacy of cyclosporine in the treatment of atopic dermatitis in dogs

OBJECTIVE: To evaluate efficacy of cyclosporine A, administered at either of 2 dosages, in dogs with atopic dermatitis (AD). DESIGN: Multicenter randomized controlled trial. ANIMALS: 91 dogs with AD. PROCEDURE: Dogs were assigned to receive placebo (30 dogs), cyclosporine at a low dosage (2.5 mg/kg [1.1 mg/lb], PO, q 24 h for 6 weeks; 30 dogs), or cyclosporine at a high dosage (5.0 mg/kg [2.3 mg/lb], PO, q 24 h for 6 weeks; 31 dogs). RESULTS: After 6 weeks, mean percentage reductions, compared with baseline scores, in scores of lesion severity were 34, 41, and 67% for dogs treated with the placebo, cyclosporine at the low dosage, and cyclosporine at the high dosage, respectively. Similarly, mean percentage reductions in pruritus scores were 15, 31, and 45%, respectively. Percentage reductions in skin lesion and pruritus scores were significantly higher for dogs given cyclosporine at the high dosage than for dogs given the placebo. Treatment efficacy was significantly associated with whether dogs had a history of seasonal AD. Percentage reductions in skin lesion and pruritus scores were high for dogs treated with cyclosporine at the highest dosage that had a history of nonseasonal AD. Dogs in all groups with seasonal AD improved during the study period. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that oral administration of cyclosporine at a dosage of 5.0 mg/kg once daily is effective in reducing severity of pruritus and skin lesions in dogs with AD, especially those with nonseasonal disease.     

Detection of a novel papillomavirus in pigmented plaques of four pugs

Pugs are predisposed to the development of deeply pigmented, slightly elevated hyperkeratotic noncancerous plaques. Polymerase chain reaction amplification of a papillomavirus (PV)-like DNA fragment from such lesions suggested that PV may be responsible for them, although the predicted virus has not yet been identified. The goal of the present study was to make use of pigmented plaques from four pugs to identify and sequence the predicted virus. Taking advantage of the circular nature of PV DNA, the entire viral genome was amplified by rolling circle amplification and restriction enzyme analysis disclosed the same pattern in all four cases. Sequencing of one of the amplificates revealed a novel canine PV, termed CPV4, related to the recently described CPV3 but clearly distinct from canine oral PV and CPV2. Thus, a novel canine PV and a method for its future diagnosis are described.     

Current evidence of skin barrier dysfunction in human and canine atopic dermatitis

Atopic dermatitis (AD) is a multifaceted disease resulting from a complex interaction between environmental and genetic factors. Both of these factors can shape skin barrier function and the immunological response of predisposed patients. There is increasing evidence that an impaired skin barrier plays a role in both human and canine AD. Although many primary skin barrier defects had already been documented in the past in humans, the recent identification of the filaggrin mutations and the fact that such mutations are now considered the most important risk factor for development of AD have further emphasized the relevance of epidermal dysfunction in human AD. Much less is known in veterinary medicine, but evidence is rapidly building to support a role for skin barrier dysfunction in canine AD. Canine AD shares many clinical and immunological similarities with its human counterpart. The similar distribution of clinical lesions and the importance of the epicutaneous route of allergen exposure provided the incentive to investigate the role of skin barrier impairments in canine AD. The purpose of this comparative review is to present the current evidence of barrier dysfunction in both human and canine AD.