Radiological diagnosis of rectocutaneous fistulas in a cat - a case report

Abscess and perirectal fistulas are common in humans but not so in animals. Fistulas located in tissues surrounding the anus are usually described in the course of furunculosis in dogs. This study presents the case of a one-year-old cat in which two rectocutaneous fistulas had formed. This process was a result of the chronic inflammation of tissues around the base of the tail due to the drainage of an abscess. The animal was referred for radiological examination with clinical signs of dyschezia. Faecal material was discharged only through the fistulas situated on both sides of the tail. The aim of the radiological examination was to preoperatively determine the course of the fistula tract and to identify their internal openings. Fistulography revealed that both fistulas were connected with each other and with the rectal lumen. Their external opening was located at the height of the 4th caudal vertebra, 1.5 cm (fistula on the right) and 2 cm (fistula on the left) from the wall of the rectum. The fistula located on the right side branched cranially. The rectal lumen in this area was significantly narrowed. Abscess formation resulting in the development of rectocutaneous fistulas has not yet been described in dogs or cats. In the present case, fistulography made it possible to identify directly the source and course of the fistula canal. This examination should be complemented by other diagnostic modalities, such as a contrast examination of the gastrointerstinal tract, ultrasound evaluation, and magnetic resonance imaging. Perianal abscess, perianal glands, rectum occlusion, fistula, fistulography Abscesses and perirectal fistulas are a common proctological disease in humans (Rickard 2005; Jander et al. 2006). They develop mainly as a result of the infection and inflammation of perirectal tissues, including the impaction and infection of the perianal glands (Hermann’s glands) located at the dentate line of the rectum, at the base of the anal crypts (Rickard 2005; Jander et al. 2006; Whiteford 2007; Abdul and Mosa Al-Rekabi 2009; Arendt et al. 2011). In animals, similar cases are rarely observed. In dogs and cats, numerous anal glands, significant in the etiopathogenesis of abscesses and fistulas in humans, are located in the intermediate zone of the mucous membrane of the rectum. They do not have much clinical significance in contrast to the perianal sinuses (sinus paranales), situated on both sides of the anus, between the external and internal anal sphincter (Duijkeren 1995; König and Liebich 2007). The wall of the sinus contains a number of large apocrine tubular glands (gll. sinus paranalis), the role of which is to secrete odoriferous substances of still unknown significance. The openings of the excretory ducts are located in the cutaneous zone of rectum mucous, and they are the most common site for the development of an inflammatory state and the formation of abscesses (Chomiak et al. 1996; Duijkeren 1995; König and Liebich 2007). Among the possible causes of perianal inflammation in animals are superinfection by faecal material, infection and impaction of the perianal glands or anal crypts with microabscesses formation, inflammation of the apocrine glands, and infection of hair follicles (Duijkieren 1995; Aronson 2003). Fistulas located in tissues surrounding the anus and connected with the anal canal are described in the course of furunculosis in dogs, ACTA VET. BRNO 2014, 83: 255–259; doi:10.2754/avb201483030255 Address for correspondence: Anna Lojszczyk-Szczepaniak University of Life Sciences, Faculty of Veterinary Medicine Department and Clinic of Animal Surgery Laboratory of Radiology and Ultrasonography Głeboka 30, 20-612 Lublin, Poland Phone: +48 (0) 814 456 155, +48 (0) 509 035 926 E-mail: [email protected] http://actavet.vfu.cz/ whose aethiology is related to multifactoral immune-mediated disorders (Jamieson et al. 2002). This study presents a radiological assessment of perianal fistulas that developed secondarily to the drainage of an abscess in the base of the tail in a cat. Similar cases have not been described in dogs or cats. Materials and Methods