6-Substituted 3-nitroimidazo[1,2-b]pyridazine for the control of hemorrhagic colitis in swine

A method of treating hemorrhagic colitis in swine which comprises, administering to the animals a therapeutically effective amount of a compound having the formula:

• ##STR28## wherein R is hydroxy, mercapto, alkoxy (C.sub.1 -C.sub.8), alkylthio (C.sub.1 -C.sub.8), phthalimidoloweralkoxy, phenylloweralkoxy, lower alkylaminoloweralkoxy, lower alkoxyloweralkoxy, hydroxyloweralkoxy, lower alkenyloxy, halobenzoylloweralkoxy, amino, alkyl (C.sub.1 -C.sub.8) amino, dialkyl (C.sub.1 -C.sub.8) amino, di(hydroxyloweralkyl)amino, hydroxyloweralkylamino, lower alkoxyloweralkylamino, lower alkenylamino, phenylloweralkylamino, pyridylloweralkylamino, cycloalkyl (C.sub.3 -C.sub.6) amino, diloweralkylaminoloweralkylamino, 1-piperidinyl, 1-pyrrolidinyl, 4-loweralkyl-1-piperazinyl, 4-lower alkoxyphenyl-1-piperazinyl, morpholino, imidazolyl, 4-carboloweralkoxy-1-piperazinyl or 4-diloweraminoloweralkyl-1-piperazinyl, sulfanilamido, alkyl (C.sub.1 -C.sub.4)-sulfanilamido;
• thiomorpholino-S,S-dioxide;
• p-chlorobenzoyl hydrazido;
• p-chlorobenzylidene hydrazino;
• nicotinylidene hydrazino loweralkylthioloweralkoxy and loweralkylsulfonyloweralkoxy or --NR.sub.4 --CO--R.sub.5 where R.sub.4 is hydrogen or alkyl C.sub.1 -C.sub.4 and R.sub.5 is alkyl C.sub.1 -C.sub.11, phenyl, 3,4-dichlorophenyl, 4-chloro-3-nitrophenyl, benzyl, mono and dihaloalkyl C.sub.1 -C.sub.4 or 2-phenoxypropionamide;
• R.sub.1 is hydrogen or alkyl C.sub.1 -C.sub.4 ;
• R.sub.2 and R.sub.3 are hydrogen or methyl;
• and the pharmaceutically acceptable acid addition salts thereof.