Da. Stoffregen et al., SUCCESSFUL THERAPY OF FURUNCULOSIS IN ATLANTIC SALMON, SALMO-SALAR L USING THE FLUOROQUINOLONE ANTIMICROBIAL AGENT ENROFLOXACIN, Journal of fish diseases, 16(3), 1993, pp. 219-228
An outbreak of furunculosis was diagnosed in an Atlantic salmon, Salmo
salar L., commercial sea-pen farm and treated with the fluoroquinolon
e antimicrobial enrofloxacin. The affected post-smolt, adult fish and
broodstock readily consumed pelleted feed impregnated with enrofloxaci
n at concentrations of 1000, 1300 and 2000 ppm, respectively, daily fo
r 10 days. Mortalities of infected post-smolts were reduced from an av
erage of 5.8% per month for the 2 months preceding therapy to 0.6% per
month for the 2 months following therapy. Infected adult fish had a 2
month mean mortality rate of 2-6% prior to enrofloxacin treatment and
0.3% over the 2 months subsequent to therapy. Apparently noninfected
(nonclinical) fish in the same farm exhibited an average monthly morta
lity of 0.4% over the 4-month study period. Sea water temperatures gra
dually rose from less than 2-degrees-C in March to approximately 12-de
grees-C in September. Mean antimicrobial tissue concentrations over th
e 10 complete days of medication were 4.58, 7.32, 4.58. 8-89 and 3.40
ppm for muscle, skin plus fat, liver, kidney and gill, respectively. W
ithin 24 h of consuming medicated feed. tissue concentrations of antim
icrobial were nearly 66% of the average concentrations for the medicat
ion period. Half-lives of elimination for the antimicrobial residues w
ere approximately 2 days for liver, 3 days for kidney, 6 days for gill
, 11 days for muscle and 22 days for skin plus fat. The producers repo
rted a successful harvest after a 180-day medication-free period.