Section 520.2280 - Sulfamethizole and methenamine(a)Specifications. Each tablet contains 250 milligrams of sulfamethizole and 250 milligrams of methenamine mandelate.(b)Sponsor. See No. 054771 in § 510.600(c) of this chapter.(c)Conditions of use in dogs and cats - (1)Amount. Administer orally 1 tablet per 20 pounds of body weight 3 times per day until clinical signs are alleviated. To reduce the possibility of relapse, continue therapy for a week to 10 days.(2)Indications for use. For treatment of urinary tract infections such as cystitis, nephritis, prostatitis, urethritis, and pyelonephritis. As an aid in the management of complications resulting from surgical manipulations of the urinary tract such as removal of calculi from the bladder, in ureterostomies, and in instrumentation of the urethra and bladder.(3)Limitations. Federal law restricts this drug to use by or on the order of a licensed veterinarian.40 FR 13838, Mar. 27, 1975, as amended at 50 FR 13561, Apr. 5, 1985; 79 FR 28831 , May 20, 2014