Management of perianal fistulae in five dogs using azathioprine and metronidazole prior to surgery.
OBJECTIVE
To evaluate combination therapy with azathioprine and metronidazole in German Shepherd Dogs with perianal fistulae.


METHODS
Prospective study.


METHODS
Five 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.


RESULTS
Signs 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.


CONCLUSIONS
Azathioprine 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.
Tisdall
P L
PL
Department of Veterinary Clinical Sciences, University of Sydney, New South Wales.
Hunt
G B
GB
Beck
J A
JA
Malik
R
R
D000284:Administration, Oral; D000818:Animals; D000890:Anti-Infective Agents / Q000627:therapeutic use*; D001379:Azathioprine / Q000627:therapeutic use*; D004283:Dog Diseases / Q000188:drug therapy* / Q000601:surgery; D004285:Dogs; D005260:Female; D007166:Immunosuppressive Agents / Q000627:therapeutic use*; D008297:Male; D008795:Metronidazole / Q000627:therapeutic use*; D011300:Preoperative Care / Q000662:veterinary; D011446:Prospective Studies; D012003:Rectal Fistula / Q000188:drug therapy / Q000601:surgery / Q000662:veterinary*; D016896:Treatment Outcome
D000890:Anti-Infective Agents; D007166:Immunosuppressive Agents; D008795:Metronidazole; D001379:Azathioprine