Water-flow variation and pharmacoepidemiology of tetracycline hydrochloride administration via drinking water in swine finishing farms.
OBJECTIVE
To evaluate variation of drinking-water flow rates in swine finishing barns and the relationship between drinker flow rate and plasma tetracycline concentrations in pigs housed in different pens.


METHODS
Cross-sectional (phase 1) and cohort (phase 2) studies.


METHODS
13 swine finishing farms (100 barns with 7,122 drinkers) in phase 1 and 100 finishing-stage pigs on 2 finishing farms (1 barn/farm) in phase 2.


METHODS
In phase 1, farms were evaluated for water-flow variation, taking into account the following variables: position of drinkers within the barn, type of drinker (swing or mounted), pig medication status, existence of designated sick pen, and existence of leakage from the waterline. In phase 2, blood samples were collected from 50 pigs/barn (40 healthy and 10 sick pigs) in 2 farms at 0, 4, 8, 24, 48, and 72 hours after initiation of water-administered tetracycline HCl (estimated dosage, 22 mg/kg [10 mg/lb]). Plasma tetracycline concentrations were measured via ultraperformance liquid chromatography.


RESULTS
Mean farm drinker flow rates ranged from 1.44 to 2.77 L/min. Significant differences in flow rates existed according to drinker type and whether tetracycline was included in the water. Mean drinker flow rates and plasma tetracycline concentrations were significantly different between the 2 farms but were not different between healthy and sick pigs. The plasma tetracycline concentrations were typically < 0.3 microg/mL.


CONCLUSIONS
Many factors affected drinker flow rates and therefore the amount of medication pigs might have received. Medication of pigs with tetracycline through water as performed in this study had questionable therapeutic value.
Dorr
Paul M
PM
Research and Development, Merial Limited, Duluth, GA 30096, USA.
Nemechek
Megan S
MS
Scheidt
Alan B
AB
Baynes
Ronald E
RE
Gebreyes
Wondwossen A
WA
Almond
Glen W
GW
D000822:Animal Husbandry / Q000295:instrumentation* / Q000379:methods; D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage* / Q000097:blood; D002851:Chromatography, High Pressure Liquid / Q000662:veterinary; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D004326:Drinking / Q000502:physiology; D004327:Drinking Behavior; D013552:Swine / Q000097:blood / Q000502:physiology*; D013752:Tetracycline / Q000008:administration & dosage* / Q000097:blood; D014867:Water / Q000737:chemistry*
D000900:Anti-Bacterial Agents; D014867:Water; D013752:Tetracycline