Evaluation of tetracycline in milk following extra-label administration of topical tetracycline for digital dermatitis in dairy cattle
Notice bibliographique
Résumé
Digital dermatitis (DD) is a painful infectious foot lesion commonly treated topically with extra-label tetracycline. Our objectives were to determine the concentrations of tetracycline in milk and plasma and to calculate a withdrawal interval following topical application at various doses. Another objective was to evaluate agreement between tests for measuring tetracycline in milk. A randomized block trial was conducted on 2 farms, where 50 cows with active DD lesions on 2 feet were allocated to 1 of 5 treatment groups (n = 10 cows per group). Treatment groups consisted of topical applications of tetracycline hydrochloride, in a paste or as a powdered form under a bandage, at 3 different dosing levels (2, 5, and 25 g) on each of the 2 affected feet. Following enrollment and treatment, samples were collected from milk, teat skin, and blood every 8 to 24 h for up to 7 d postdosing. Concentrations of tetracycline were measured by liquid chromatography-mass spectrometry and milk samples were further tested using the Charm ROSA TET test (Charm Sciences Inc., Lawrence, MA). Tetracycline was present in milk, plasma, and teat skin from all treatment groups. Tetracycline concentrations varied depending on time of sampling, method of application, and dosing level. At 8 h post-treatment, 11% of cows had tetracycline present in milk higher than 100 ng/mL (ppb) but none higher than 300 ng/mL. The 25-g treatment group had the longest estimated withdrawal interval, the highest observed concentrations (210-244 ng/mL) of tetracycline present in milk, and the longest observed consecutive period of tetracycline presence (from 8 to 72 h) among all treatment groups. Compared with liquid chromatography-mass spectrometry, the Charm test had a sensitivity of 77 and 100% for measuring tetracycline in milk at ≥30 and ≥100 ng/mL, respectively. Post-treatment samples of the teat skin were taken from 15 cows on 6 occasions, and every cow had tetracycline present in at least 1 of those 6 samples. This confirms an association between topical DD treatment with tetracycline and contamination of the teat. A total of 22% of blood samples had detectable tetracycline, and the majority (63%) occurred at 8 h post-treatment. At 100 ng/mL, the estimated cow-level milk withdrawal interval ranged from 0 to 70 h. At 300 ng/mL, the estimated cow-level withdrawal interval ranged from 0 to 34 h, and was 0 h at the bulk tank level. We recommend that conservative measures be adopted after extra-label use of topical tetracycline for DD treatment, including using a low dose and strategic post-treatment testing for tetracycline-class drugs in milk.
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Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,002 | 0,001 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,001 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».