Canine peritoneal larval cestodosis in a dog

Abstract

Mesocestoides spp. are parasites in intestines of birds and mammals, including humans (7, 9). Taxonomic classification of the cestodes belonging to the Mesocestoididae family is unclear according to recent morphological and genetical studies (12, 13, 17). This family may not take be part of the order Cyclophyllidea. In respect to biological (life cycle with three hosts), morpho-anatomical (the median location of the genital pore and vitellarium consisting of two compact masses) and sperm characters (rotation of flagellum, the number of axonemes and twisting of cortical microtubules), Mesocestoididae spp. differ from the other members of Cyclophyllidea (9, 13). Also, molecular analysis reveals that Mesocestoididae spp. are basal to the Tetrabothriidea (12). The three species of Mesocestoides taken into consideration are as follows: Mesocestoides vogae (syn. M. corti), Mesocestoides line atus and Mesocestoides leptothylacus (syn. M. litteratus) (10). M. vogae is found in the intestine of dogs (8) and bobcats (18) and M. lineatus in the small intestine of wild carnivores, dogs and cats. Final hosts of M. leptothylacus are foxes, cats and dogs (7). The complete life cycle of Mesocestoides spp. is still obscure (7). The infective larval stage (tetrathyridium) of Mesocestoides spp. is found in the abdominal cavity and on lungs and livers of intermediate hosts such as amphibians, reptiles, birds and small mammals (7, 10). The life cycle is completed in definitive carni vorous hosts by eating intermediate hosts. Adult cestodes develop in the intestine of definitive hosts following a prepatent period of approximately 2–3 weeks (7, 10). Infections with adult Mesocestoides spp. are reported with a quite different incidence in various carnivorous animals such as dogs (6, 19, 21), red foxes (6, 11), wolves (1) and jackals (6). Occasionally, synchronous presence of both the adult Mesocestoides spp. and its infective larval stages in the same definitive host occurs (19) and in these cases the more severe clinic and pathologic outcomes are reported (7, 19). Metacestode stages of Mesocestoides spp. in the abdominal cavity of dogs results in canine peritoneal larval cestodosis (20). Anorexia, peritonitis, ascites, leukocytosis, tissue damage, granuloma formation and encapsulation are observed in animals infected with metacestode stages (7). The infection of the definitive host is simply detected by observation of proglottids with a typical paruterine organ excreted with the faeces (7, 10). In contrast, the detection of peritoneal larval cestodosis in dogs is more complex. The possible methods used for diagnosis of peritoneal larval cestodosis are necropsy (19), ultrasonography (20), histological and cytological examination (3). These methods together with molecular tools are subsequently used for identification of peritoneal larval cestodosis (2, 4, 22). Data on Mesocestoides species responsible for peritoneal larval cestodosis in dogs are limited (2, 22). The aim of this study is to demonstrate a clinical case of peritoneal larval cestodosis in a dog combined with the determination of the parasitic larvae by mole cular diagnosis.