Caracterización macroscópica y microscópica de la Pythiosis gastrointestinal de perros en Venezuela / Macroscopic and microscopic characterization of dog gastrointestinal Pythiosis in Venezuela

RESUMEN

La Pythiosis es una enfermedad granulomatosa crónica que afecta a humanos y a varias especies animales, causada por el oomyceto Pythium insidiosum. En Venezuela, la pythiosis en perros ha sido reportada en su forma gastrointestinal mostrando una marcada frecuencia de diagnóstico compatible en pacientes con diarrea hemorrágica crónica. Por tal motivo, este estudio se planteó como objetivo caracterizar macroscópica y microscópicamente la pythiosis gastrointestinal en perros del estado Lara, Venezuela. Para ello se desarrolló una investigación de campo, de tipo descriptiva. La muestra consistió en 46 perros con diagnóstico histopatológico compatible con pythiosis gastrointestinal, referidos al Servicio de Diagnóstico Anatomopatológico del Hospital Veterinario “Dr. Humberto Ramírez Daza”; periodo enero 2001- julio 2007. El estudio macroscópico evaluó las lesiones de aspecto tumoral ubicadas en el estómago e intestino de los perros en estudio. Para la evaluación microscópica, se tomaron muestras de las lesiones, las cuales se fijaron en formol buferado al 10% y fueron sometidas al procesamiento histológico de tejidos para ser finalmente coloreadas con Hematoxilina y Eosina, Metenamina de Plata de Grocott. Posteriormente, cada corte de tejido se observó al microscopio óptico en toda su extensión. Los resultados de esta investigación arrojaron que la pythiosis gastrointestinal se caracteriza macroscópicamente por ser una lesión multinodular, de aspecto tumoral que involucra estómago e intestino. Histopatológicamente presenta gastritis y enteritis piogranulomatosa multifocal extensiva, en la cual el agente etiológico conforma micelios constituidos por hifas largas, pobremente septadas, de 3 a 5 µm de diámetro y ramificadas en ángulo de 90°.

ABSTRACT

The pythiosis is a fungal, chronic, granulomatous disease that affects humans and several animal species. The pythiosis is caused by the oomycete Pythium insidiosum . In Venezuela, dog pythiosis has been reported in its gastrointestinal form, showing a marked frequency of gastrointestinal diagnosis, compatible with that seen in patients with chronic hemorrhagic diarrhea. The purpose of this investigation was to characterize from the macroscopic and microscopic standpoint, gastrointestinal pythiosis in dogs of the State of Lara, Venezuela. A descriptive field research was conducted. A total of 46 dogs with a histological diagnosis compatible with gastrointestinal pythiosis were chosen. The dogs had been referred to the Pathological Diagnostic Service of the Veterinary Hospital “Dr. Humberto Ramírez Daza”, from January 2001 to July 2007. Gastrointestinal samples were submitted for macroscopic evaluation of tumorous lesions located in the stomach and intestine of dogs under study. For the microscopic assessment, samples were taken and fixed in 10% buffered formaldehyde. The samples were subsequently subjected to histological processing and stained with Hematoxilin and Eosin and Grocott Methenamine Silver. Then, cuts of tissues were obtained and observed in its entire extension under a light microscope. The results of the present investigation show that gastrointestinal pythiosis is macroscopically characterized by a tumor-like moltinodular lesion that involves both the stomach and intestine. Histopathologically, the lesions showed multifocal gastritis and extensive pyogranulomatous enteritis where the etiological agent forms mycelia with long hyphae, few septa, branched in 90º angles, and a diameter of 3 to 5 µm.