Biology, diagnosis and treatment of Malassezia dermatitis in dogs and cats Clinical Consensus Guidelines of the World Association for Veterinary Dermatology.

BACKGROUND: The genus Malassezia is comprised of a group of lipophilic yeasts that have evolved as skin commensals and opportunistic cutaneous pathogens of a variety of mammals and birds. OBJECTIVES: The objective of this document is to provide the veterinary community and other interested parties with current information on the ecology, pathophysiology, diagnosis, treatment and prevention of skin diseases associated with Malassezia yeasts in dogs and cats. METHODS AND MATERIAL: The authors served as a Guideline Panel (GP) and reviewed the literature available prior to October 2018. The GP prepared a detailed literature review and made recommendations on selected topics. The World Association of Veterinary Dermatology (WAVD) Clinical Consensus Guideline committee provided guidance and oversight for this process. The document was presented at two international meetings of veterinary dermatology societies and one international mycology workshop; it was made available for comment on the WAVD website for a period of six months. Comments were shared with the GP electronically and responses incorporated into the final document. CONCLUSIONS AND CLINICAL IMPORTANCE: There has been a remarkable expansion of knowledge on Malassezia yeasts and their role in animal disease, particularly since the early 1990's. Malassezia dermatitis in dogs and cats has evolved from a disease of obscurity and controversy on its existence, to now being a routine diagnosis in general veterinary practice. Clinical signs are well recognised and diagnostic approaches are well developed. A range of topical and systemic therapies is known to be effective, especially when predisposing factors are identified and corrected.

Immediate hypersensitivity to leaf extracts of Callisia fragrans (inch plant) in a dog.

Contact with members of the plant family Commelinaceae, which includes wandering jew (Commelina spp. formerly called Tradescantia spp.) and inch plant (Callisia fragrans), can cause cell-mediated contact dermatitis in dogs. However, reports of canine IgE-mediated hypersensitivity to these plants have not been published. The purpose of this study was to discover whether IgE antibodies specific for extractable components of C. fragrans could be identified in serum from a dog that had anaphylactic shock after exposure to the plant and after skin patch testing with the sap from a leaf of C. fragrans. Separate aqueous extracts of leaves and flowers of C. fragrans were subjected to sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting. Serum from a dog with no history or symptoms of any allergies showed no specific IgE antibodies against the leaf extract. Serum from a dog with clinical symptoms of delayed, but not immediate hypersensitivity to leaf sap from C. fragrans, showed only minor IgE recognition of a single 65 k component in sap extracted from leaves harvested in summer but not in winter. However, IgE antibodies to a serum dilution of 1:200 specific for several components of the leaf extract were seen in serum from the dog that had anaphylactic shock after exposure to sap. The molecular weights of these molecules were in the range 51 k to 83 k. The bands on the immunoblots did not match with prominently stained protein bands in the gel, but instead identified molecules in a lightly stained area of the gel with diffuse bands. Testing for glycans indicated that the carbohydrate side chains of glycoproteins contributed significantly to the immunoreactivity of the putative allergens. All three dog sera failed to show any immunoreactivity against the extract from the flowers of C. fragrans.

A review of the biology of canine skin with respect to the commensals Staphylococcus intermedins, Demodex canis and Malassezia pachydermatis.

Abstract Skin disease associated with the cutaneous commensal organisms Staphylococcus intermedius, Malassezia pachydermatis and Demodex canis is frequently encountered in veterinary medicine. In treatment the aim is elimination of the commensal, but recurrence of skin disease is not unusual. In this review, these potentially pathogenic commensals and their ecology are discussed with particular reference to skin biology and the surface ecosystem. The strategies employed by the micro-organisms for survival and the defence mechanisms of the host are considered. Disease occurs when the virulence of the commensal overwhelms the resistance of the host. It is hoped that an understanding of the complex nature of the skin and its commensals will lead to a better understanding of those diseases associated with commensals and in consequence more effective treatment. Résumé- Les dermatoses associées aux organismes commensaux cutanés Staphylococcus intermedius, Malassezia pachydermatis et Demodex canis sont fréquentes en médecine vétérinaire. Le traitement vise àéliminer le commensal, mais les récidives sont fréquentes. Dans cet article, les commensaux potentiellement pathogènes et leur écologie sont discutés avec une référence particulière à la biologie cutanée et à l'écosystème de surface. Les stratégies employées par les microorganismes pour survivre et les mécanismes de défense de l'hote sont présentés. La pathologie se développe lorsque la virulence du commensal outrepasse la résistance de l'hote. Il faut espérer que la compréhension de la nature complexe de la peau et de ses commensaux, permettent une meilleure compréhension des pathologies associées à ces commensaux et par conséquent un traitement plus efficace. [Mason, I. S., Mason, K. V., Lloyd, D. H. A review of the biology of canine skin with respect to the commensals Staphylococcus intermedius, Demodex canis and Malassezia pachydermatis (Une revue de la biologie de la peau concernant les commensaux Staphylococcus intermedius, Demodex canis et Malassezia pachydermatis). Veterinary Dermatology 1996; 7: 119-132.] Resumen En medicina veterinaria son frecuentes las dermatopatías asociadas a los microorganismos comensales Staphylococcus intermedius, Demodex canis y Malassezia pachydermatis. El tratamiento busca la eliminatión del comensal, aunque no son raras las recidivas. En esta revisión se discute la ecología de estos comensales potencialmente patógenos, con especial énfasis en la biologia cutánea y el ecosistema superficial. Se tienen en cuenta las estrategias para la supervivencia utilizadas por los microorganismos y los mecanismos de defensa del huésped. La enfernedad se desarrolla cuando la virulencia del comensal supera la resistencia del huésped. Se espera que el mejor conocimiento de la naturaleza compleja de la piel y de sus comensales llevará a un mejor conocimiento de las enfermedades asociadas a los comensales y, consecuentemente, a un tratamiento más efectivo. [Mason, I. S., Mason, K. V., Lloyd, D. H. A review of the biology of canine skin with respect to the commensals Staphylococcus intermedius, Demodex canis and Malassezia pachydermatis (Revision de la biologia cutánea con respecto a los comensales Staphylococcus intermedius, Demodex canis y Malassezia pachydermatis). Veterinary Dermatology 1996; 7: 119-132.] Zusammenfassung- Hauterkrankungen in Verbindung mit den kutanen, kommensalen Organismen Staphylococcu intermedius, Malassezia pachydermatis und Demodex canis werden in der Veterinärmedizin häufig angetroffen. Das Ziel der Behandlung ist die Elimination der Kommensalen, aber die Rezidivierung der Hauterkrankung ist nicht ungewöhnlich. In dieser Übersicht werden diese potentiell pathogenen Kommensalen und ihre Ökologie mit speziellem Bezug zur Biologie der Haut und des Ober-flächenökosystems diskutiert. Die Überlebensstrategien dieser Mikroorganismen und die Abwehrmechanismen des Wirtes werden berücksichtigt. Eine Erkrankung tritt auf, wenn die Virulenz des Kommensal die Widerstandskraft des Wirtes übertrifft. Man hofft, daß das Verstehen der komplexen Natur der Haut und ihrer Kommensalen zum besserem Verständnis dieser mit den Kommensalen verbundenen Krankheiten und damit in der Folge zu wirksamerer Behandlung führt. [Mason, I.S., Mason, K.V., Lloyd, D.H. A review of the biology of canine skin with respect to the commensals Staphylococcus intermedius, Demodex canis and Malassezia pachydermatis (Übersicht über die Biologie der Haut des Hundes mit Berücksichtigung der Kommensalen Staphylococcus intermedius, Demodex canis und Malassezia pachydermatis). Veterinary Dermatology 1996; 7: 119-132.].

The Use of Insect Development Inhibitors as an Oral Medication for the Control of the Fleas Ctenocephalides felis, Ct. canis in the Dog and Cat.

Résumé- Il existe deux inhibiteurs de croissance des insectes (ICI) sous forme orale pour le contrôle des puces. Le lufénuron s'administre une fois par mois à la dose de 10 mg/kg chez le chien et 30 mg/kg chez le chat. La cyromazine s'administre quotidiennement à la dose de 10 mg/kg en association avec la diethylcarbamazine chez le chien. Aucun des deux produits n'est actif sur la puce adulte, mais cause plutôt une interruption de la production de chitine normale par différents modes d'actions spécifiques. Ceci entraine la mort des formes immatures de puces. Par conséquent, les 2 produits contrôle l'infestation par les puces adultes sur l'animal par le biais de l'élimination des formes immatures présentes dans le milieu. Il existe un délai de 6 à 8 semaines entre 1'administration d'inhibiteurs de croissance des insectes (ICI) et la reduction du nombre de puces adultes sur les animaux traités. Cette période réfractaire est due à la survie de puces immatures présentes dans le milieu avant le traitement aux ICI; elle peut être réduite si l'on démarre le traitement oral par les ICI simultanément à un traitement insecticide du milieu environnant et de l'animal. [Shipstone, M. A., Mason, K. V. The use of Insect Development Inhibitors as an oral medication for the control of the fleas Ctenocephalides felis, Ct. canis in the dog and cat (Utilisation d'inhibiteurs de croissance des insectes sous forme orale pour le contrôle des puces Ctenocephalides felis, Ct. canis chez le chien et le chat). Resumen- Existen dos inhibidores del desarrollo de insectos (ICI) para el control de pulgas. El Lefenuron se administra una vez al mes a una dosis de 10 mg × Kg-1 en perros y 30 mg × Kg-1 en gatos. La Ciromacina se administra diariamente a una dosis de 10 mg × Kg-1 en combinación con citrato de dietilcarbamacina en perros. Ninguno de estos compuestos produce efecto en pulgas adultas, sino que causa una interrupción en la producción normal de quitina por distintos mecanismos de acción. Ello causa la muerte del parásito en estadíos de inmadurez y crecimiento. Así, ambos controlan la infestación por pulgas adultas en el animal mediante la eliminación de estadíos vitales de la pulga. Existe un espacio de tiempo de 6-8 semanas entre el inicio de la aministración de ICA y la reducción del número de pulgas en animales tratados. Ésto et debido a la supervivencia de pulgas inmaduras que se encontraban en el entorno antes del inicio del tratamiento con ICI; este periodo de tiempo se puede reducir iniciando el tratamiento oral con ICI junto con tratamiento insecticida de la vivienda y sobre el animal. [Shipstone, M. A., Mason, K. V. The use of Insect Development Inhibitors as an oral medication for the control of the fleas Ctenocephalides felis, Ct. canis in the dog and cat (El uso de inhibidores del desarrollo de insectos como medicación oral para el control de las pulgas Cenocephalides felis y Ct. canis en el perro y en el gato). Abstract- There are two oral Insect Development Inhibitors (IDI) for the control of fleas. Lufenuron is administered once a month at 10 mg × kg-1 for dogs and 30 mg × kg-1 for cats. Cyromazine is administered daily at 10 mg kg-1 in combination with diethylcarbamazine citrate for dogs. Neither compound exerts an effect on the adult flea, but rather causes an interruption in normal chitin production through different specific modes of action. This causes death of the immature, developmental life stages of the flea. Thus, both control the adult flea infestation on the animal via the elimination of the environmental life stages of the flea. There is a lag phase of 6-8 weeks between the initiation of IDI administration and reduction in the number of adult fleas on the treated animals. The lag phase results from the survival of immature fleas that were present in the environment before the onset of IDI treatment; it can be reduced by initiating oral IDI treatment in combination with premise and on-animal insecticide treatments.