Management of perianal fistulae in five dogs using azathioprine and metronidazole prior to surgery

• Published in: Australian veterinary journal 1999-06, Vol.77 (6), p.374-378
• Main Authors: Tisdall, P.L.C, Hunt, G.B, Beck, J.A, Malik, R
• Format: Article
• Language: English
• Subjects: Administration, Oral; anal furunculosis; Animals; Anti-Infective Agents - therapeutic use; anus; azathioprine; Azathioprine - therapeutic use; combination drug therapy; Dog; Dog Diseases - drug therapy; Dog Diseases - surgery; Dogs; drug therapy; Female; fistula; German Shepherd Dogs; immunosuppressive agents; Immunosuppressive Agents - therapeutic use; Male; metronidazole; Metronidazole - therapeutic use; perianal fistula; Preoperative Care - veterinary; Prospective Studies; Rectal Fistula - drug therapy; Rectal Fistula - surgery; Rectal Fistula - veterinary; surgery; treatment; Treatment Outcome
• ISSN: 0005-0423; 1751-0813
• DOI: 10.1111/j.1751-0813.1999.tb10307.x

ObjectiveTo evaluate combination therapy with azathioprine and metronidazole in German Shepherd Dogs with perianal fistulae. DesignProspective study ProcedureFive dogs (31.5 to 36.0 kg) with perianal fistulae were treated with azathioprine (50 mg per dog orally every 24 h) and metronidazole (400 mg per dog orally every 24 h). Patients were re‐evaluated at 2 week intervals by inspection, palpation, photographs of the perineal region and assessment of white blood cell counts where possible. Treatment was continued until improvement in lesions reached a plateau. Surgical excision of residual fistulae and anal sac remnants was then performed, with medical therapy continued for an additional 3 to 6 weeks. ResultSigns attributable to anal irritation were reduced or eliminated in all dogs within 2 weeks, although visible healing of lesions progressed more slowly. Ulcerated lesions reduced in surface area and depth, and some fistulae healed completely. Non‐healing areas were usually associated with anal sac rupture or chronic fibrosis. Visible improvement typically reached a plateau 4 to 6 weeks after commencing treatment. Immunosuppressive therapy continued for 5 to 24 weeks before surgical intervention to remove anal sacs (four dogs) and/or residual fistulae (five dogs). All dogs remain disease free 7 to 10 months postoperatively. No important complications of treatment were encountered. ConclusionAzathioprine with metronidazole effectively reduced perianal irritation, and the severity and extent of lesions prior to surgery. Treatment was economical even in large dogs and associated with few untoward sequelae. The combined use of immunosuppressive and antimicrobial therapy followed by surgery minimised potential morbidity associated with aggressive use of either medical of surgical treatment alone.