Ultrasonographic diagnosis of peritoneal cestodiasis caused by Mesocestoides SPP in dogs.

Canine peritoneal larval cestodiasis (CPlC) is a parasitological infestation of the peritoneal cavity of wild and domestic carnivores with Mesocestoides spp. larvae. Mesocestoides spp. are considered zoonotic, although many aspects of the biology of these worms still remain unknown and despite hypothesizing a foodborne origin, no evidence for the route for human infection has been shown (fuentes et al., 2003. am J Trop med hyg, 68:566–67). Several recent surveys have shown evidence of new genetic variants within this genus, thus requiring further investigations (varcasia et al., 2018. Parasit vectors, 11: 619). adult Mesocestoides tapeworms reside within the small intestine of carnivores, while their larvae occasionally penetrate the host’s intestinal wall, causing a potentially life-threatening peritonitis. Severity of infection as well as the host age and response influences the prognosis significantly, and early diagnosis and treatment are essential. however, due to the lack of specific symptoms, this condition is underdiagnosed. abdominal ultrasonography (uS) had a crucial role in the CPlC, since it allows a suspected diagnosis that can be confirmed trough the parasitological or molecular identification, but there are just few studies including uS examination of affected dogs (venco et al., 2005. vet radiol ultrasound, 46: 417-22; Carta et al., 2021. Parasitol res, 120: 1727-35). The findings during abdominal uS include often the presence of abdominal effusion characterized by echogenic and particulate fluid and several rounded to cylindrical anechoic, cystic structures measuring from 1–3 mm in diameter up to 3-4 centimeters. Several forms of metacestodes can be observed free-floating in the abdominal fluid or enclosed in small cysts and/or adherent to the serous surfaces, which appeared roughened and irregular. uS allows to distinguish on the serosal surface the well-formed tetrathyridia, clearly hypoechoic with enlarged heads and a slender tail, or the so-called acephalic larvae that appear as rounded anechoic fluid-filled cystic structures. The omentum and the mesenteric fat can appear hyperechoic with a coarse and irregular echostructure. visualization of these features allowed a presumptive diagnosis, but all the diseases causing abdominal distension and ascites must be considered as differential diagnosis. uS is also used for the ultrasonographic-guided collection of abdominal fluid and specimens for confirmation, and for therapy management and follow-up. In conclusion, it is essential to promote the development and application of early diagnostics, for which uS is considered crucial, in order to prevent severe clinical manifestations and thus for the probability of recovery from disease, since anthelmintic treatments may result in a rapid resolution of clinical manifestations and a reduction of parasitic infestation, even not fully effective in eradicating the infection and preventing the disease recurrence.