Table 2.
Assignment of DDDbovCA and DCDbovCA values for antimicrobial agents used systemically through the oral route for cattle in Canada.
| Antimicrobial agent | Combined with another antimicrobial agent in products? | Antimicrobial class | Category according to Health Canada | dddbovCA (mg per kg per day) | dcdbovCA (mg per kg per course) | DDDbovCA (g per animal per day) | DCDbovCA (g per animal per course) |
|---|---|---|---|---|---|---|---|
| Antimicrobial agents used in oral products other than medicated premixes | |||||||
| Benzylpenicillin (Penicillin G) | Combined with streptomycin | Beta-lactamase sensitive penicillins | II | 5.3 | 13.2 | 0.53 | 1.32 |
| Monensin | No | Ionophores | IV | 0.52 | 49.8 | 0.34 | 32.40 |
| Neomycin sulfate | No | Aminoglycosides | II | 16.3 | 48.8 | 1.63 | 4.88 |
| Neomycin sulfate | Combined with sulfonamides or tetracyclines | Aminoglycosides | II | 14.1 | 51.1 | 1.41 | 5.11 |
| Oxytetracycline | No | Tetracyclines | III | 12.3 | 48.3 | 2.43 | 10.23 |
| Oxytetracycline | Combined with neomycin | Tetracyclines | III | 12.7 | 57.0 | 1.27 | 5.70 |
| Streptomycin sulfate | Combined with benzylpenicillin | Aminoglycosides | II | 27.3 | 68.1 | 2.73 | 6.81 |
| Succinylsulfathiazole | Combined with neomycin | Sulfonamides | III | 57.6 | 144.0 | 5.76 | 14.40 |
| Sulfaguanidine | Combined with neomycin and sulfathiazole | Sulfonamides | III | 29.8 | 104.2 | 2.98 | 10.42 |
| Sulfamerazine | Combined with sulfonamides | Sulfonamides | III | 4.5 | 27.7 | 1.35 | 8.31 |
| Sulfamethazine (Sulfadimidine) | No | Sulfonamides | III | 101.6 | 406.1 | 30.47 | 121.85 |
| Sulfamethazine (Sulfadimidine) | Combined with neomycin or sulfonamides | Sulfonamides | III | 59.0 | 195.8 | 13.57 | 44.35 |
| Sulfanilamide | Combined with sulfonamides | Sulfonamides | III | 91.4 | 91.4 | 27.42 | 27.42 |
| Sulfapyridine | No | Sulfonamides | III | 179.2 | 537.5 | 53.76 | 161.25 |
| Sulfapyridine | Combined with sulfonamides | Sulfonamides | III | 24.8 | 99.1 | 7.44 | 29.73 |
| Sulfathiazole | Combined with neomycin and sulfaguanidine, or sulfonamides | Sulfonamides | III | 44.2 | 142.6 | 12.67 | 40.69 |
| Tetracycline | No | Sulfonamides | III | 10.4 | 60.0 | 1.04 | 6.00 |
| Tetracycline | Combined with neomycin | Tetracyclines | III | 13.3 | 60.0 | 1.33 | 6.00 |
| Antimicrobial agents used in medicated premixes | |||||||
| Chlortetracycline | No | Tetracyclines | III | 0.66 | 59.4 | 0.09 | 8.10 |
| Lasalocid | No | Ionophores | IV | 0.89 | 79.8 | 0.27 | 23.94 |
| Monensin | No | Ionophores | IV | 0.53 | 47.5 | 0.21 | 18.77 |
| Oxytetracycline | No | Tetracyclines | III | 1.1 | 99.0 | 0.09 | 8.33 |
| Salinomycin | No | Ionophores | IV | 0.33 | 30.0 | 0.10 | 9.00 |
| Tilmicosin | No | Macrolides | II | 12.5 | 175.0 | 3.75 | 52.50 |
| Tylosin | No | Macrolides | II | 0.22 | 19.8 | 0.07 | 5.94 |
dddbovCA, Canadian Defined Daily Dosage for cattle (in mg/kg/day); DDDbovCA, Canadian Defined Daily Dose for cattle (in g/animal/day); dcdbovCA, Canadian Defined Course Dosage for cattle (in mg/kg/course); DCDbovCA, Canadian Defined Course Dose for cattle (in g/animal/course). Dosages and doses were not determined for combined chlortetracycline and sulfamethazine (1 premix), and for combined neomycin sulfate and oxytetracycline (1 premix) (see Supplementary 1.2).