BACKGROUND: Toxocara canis is a zoonotic disease that commonly infects canids. Mammals and birds are sometimes infected with this disease as paratenic hosts. It can also cause accidental infection in humans. The increase in the number of stray dogs, the expansion of urban gardens, and the proximity of dogs to humans increase the risk of human infection with Toxocara canis.OBJECTIVES: This study aims to determine the prevalence of Toxocara canis infection in dogs and foxes in Zanjan province, Iran.METHODS: A total of 484 fecal samples of stray dogs (n=355), rescue dogs (n=49), guard dogs (n=50), and foxes (n=30) in Zanjan were randomly collected from June 2021 to February 2022. The microscopic examination was done following formalin-ethyl acetate sedimentation procedures. Finally, the PCR method was used to confirm the presence of Toxocara canis in positive samples.RESULTS: Microscopic study revealed that, out of 484 samples, 21 (4.3%) were positive for Toxocara/ Toxascaris eggs. Between these positive samples of dogs and foxes, only 6 samples from dog feces were confirmed as a Toxocara canis infection by the PCR method.CONCLUSIONS: There is an increase in the prevalence of Toxocara canis infection in stray dogs in Zanjan, Iran. Given the presence of dogs in parks and residential areas, there is a risk of human infection with Toxocara canis, emphasizing the importance of adhering to treatment and prevention protocols in dealing with stray dogs.

Microvascular circulation of the ascending colon in healthy horses was studied using microangiography, light microscopy, and scanning electron microscopy. The pelvic flexure with 30 cm of ventral and dorsal colon attached was removed from 14 adult horses immediately after horses were euthanatized. The lumen was flushed with warm water, and this section of the ascending colon was placed in a 37-C bath of isotonic NaCl. In sections from 8 horses, colic vessels were perfused with a radio-opaque medium for microangiography. After angiographic evaluation, tissue sections were prepared for light microscopic observation, using standard histologic methods. In sections from 6 horses, injection replicas were made by perfusing the vessels with 2 types of plastics. The results of microangiography, light microscopy, and scanning electron microscopy of vascular replicas were correlated, providing acomprehensive documentation of the microvasculature of the ascending colon at the pelvic flexure. Arteries branched from mesenteric colic vessels approximately every 2 cm toward the colonic tissue. Immediately after branching, arterial vessels formed an anastomotic plexus, the colonic rete. However, each branch from the colic vessel eventually continued into the colonic tissue. A second set of vessels originated from the colonic rete and supplied the mesenteric lymph nodes. Arterial vessels penetrated the tunica muscularis into the sub-mucosa 3 to 4 cm toward the antimesenteric border forming a submucosal vascular network. From the submucosal arterioles, branching took place at right angles to supply the mucosal capillaries. Capillaries surrounded the colonic glands and anastomosed at the luminal surface, forming a superficial luminal honeycomb-appearing vascular plexus. Venules, sparsely distributed, drained the superficial plexus. Arterial venous anastomoses were not observed within the mucosa.