[Study of the elimination of residues and local tissue injury following intramuscular injection of a solution of the combination trimethoprim/sulfatroxazole in pigs]

Two different studies are described. The first study deals with the elimination of residues of trimethoprim (TMP), sulfatroxazole (STX) and its main metabolite N4-acetyl-sulfatroxazole (N4-acetyl-STX) in pigs. Thirty -six pigs were treated with trimethoprim/sulfatroxazole IM in the nec k at a dosage of 16 mg/kg body weight for five days. Groups of four pig s were slaughtered at different time intervals. The study showed that concentration of STX, N4-acetyl-STX and TMP in edible tissues and at the injection sites were below 0.1 ppm on day nine after the last injection. S TX was eliminated the slowest, and STX can therefore be selected as a marker for residues of the trimethoprim/sulfatroxazole formulation in the tissues. The second study deals with irritation aspects of this trimethoprim /sulfatroxazole formulation. Four pigs of 32-35 kg were treated IM w with trimethoprim/sulfatroxazole and benzylpenicillin sodium. Each pig received the same injection volume, namely four trimethoprim/sulfatroxazole injections (16 mg/kg body weight per injection site), two in the back and two in the neck muscle, and two benzylpenicillin sodium injections (20,000 I.U./kg body weight per injection site), in the back muscle. All pigs were slaughtered 14 days after treatment and the extent of the irritation was compared. There were no differences between trimethoprim/sulfatroxazole and benzylpenicillin sodium with regard to irritation at the injection site in the back muscle. The irritation in the neck site was statistically less prominent than that in the back muscle and was considered not to affect the quality of the meat.

Field trial to determine the efficacy of two doses of 1 alpha-hydroxycholecalciferol in the prevention of milk fever

The efficacy of 1 alpha-hydroxycholecalciferol (1 alpha-HCC) for the prevention of milk fever has been tested in a controlled field trial using a total of 601 cows on 18 farms with a history of a high incidence of milk fever. The trial protocol proposed two doses of 1 alpha-HCC with the first injection seven days before the predicted calving date and a second injection five to seven days later if the cow had not calved. Of 301 cows receiving either one or two injections of 1 alpha-HCC, 70 had milk fever, and of 300 cows that received a placebo, 102 had milk fever. The difference in incidence between the two groups was statistically significant (P = 0.005) and indicated an overall efficacy of 32 per cent for treatment with 1 alpha-HCC. An improved efficacy was demonstrated in 67 cows that received two injections of 1 alpha-HCC with the second injection administered either on the day of calving or one day previously (60 per cent efficacy). For 42 cows that received a single injection of 1 alpha-HCC between two and five days before calving an efficacy of 79 per cent was achieved.

A field trial of 1alpha-hydroxycholecalciferol (1alpha-OH D3) in the prevention of milk fever

The efficacy of 1alpha-OH cholecalciferol for the prevention of milk fever has been tested in a controlled field trial using 597 cows on 19 farms all of which had previously had a high incidence of milk fever. Of 293 cows receiving 1alpha-OH cholecalciferol 34 had milk fever and of 304 control cows 51 had milk fever. Although there was an apparent efficacy of 31 per cent the difference in incidence was not statistically significant. There was no effect if 1alpha-OH cholecalciferol was administered less than 24 hours before the cows succumbed to milk fever. However, if 1alpha-OH cholecalciferol was administered more than 24 hours and less than one week before the occurrence of milk fever the efficacy increased to 61 per cent and the effect was highly significant.