Banca de DEFESA: MARISA BEATRIZ DA SILVA ROCHA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : MARISA BEATRIZ DA SILVA ROCHA
DATA : 05/03/2020
HORA: 15:00
LOCAL: Sala Prof Laerte Grisi - LQEPV
TÍTULO:

Therapeutic and persistent efficacy of 1% fipronil “pour on” in horses against the Dermacentor nitens tick and associated pharmacokinetics

PALAVRAS-CHAVES:

control; ectoparasites; equine;

PÁGINAS: 57
GRANDE ÁREA: Ciências Agrárias
ÁREA: Medicina Veterinária
RESUMO:

The main species of tick to develop economic losses and significant health damage to equine production in Brazil is Dermacentor nitens. However, control studies of this tick in experimental models "in vivo" with evaluation and construction of a plasma concentration curve are scarce. This reduces the options of chemical bases available for an efficient control of this parasite. Currently the options employed are cypermethrins in paste or parasiticide bath emulsion. Fipronil, belonging to the class of phenylpyrazoles, is widely used in veterinary medicine to control ectoparasites with its proven tick effectiveness in different species of ticks and hosts. The objective of this study was to use fipronil applied topically to “pour on” in horses of the Brazilian pony breed, at a dose of 1mg / kg, in the control of D. nitens, using studies of therapeutic and residual efficacy as evaluation criteria. , and construction of the plasma concentration curve by bioanalytical method of both fipronil and its active metabolite, fipronil sulfone. To carry out the study, 14 horses were housed in individual stalls on day -34 and from day -31 onwards, they were infested with approximately 1750 D. nitens larvae on alternate days until day -1. After excluding two animals from the study and randomization based on the falls of engorged females on days -3, -2, -1, two experimental groups were established with six animals each, treated and control. On day 0, also classified as treatment day, it was administered to the treated group 1% fipronil “pour on” at a dose of 1mg / kg to determine the therapeutic efficacy. In addition, horses were infested at weekly intervals for 3 consecutive weeks to determine persistent, or residual, effectiveness. Topically administered fipronil reached the systemic circulation (Cmax1 = 0.71 ± 0.30 and Cmax2 = 0.56 ± 0.27 μg / mL), being rapidly absorbed (tmax1 = 7.00 ± 0.00 and 15.00 ± 0.00 days) and eliminated slowly (t1 / 2 = 8.54 ± 2.03 days), while fipronil sulfone maintained a very linear concentration with slow release (Cmax = 0.27 ± 0.06 μg / mL and tmax = 18.00 ± 3.29) and elimination almost 5 times slower than fipronil (t1 / 2 = 42.06 ± 23.02) being quantified at significant levels even 48 days after treatment (0.140 ± 0.034 μg / mL). The results of the therapeutic efficacy of fipronil were significant (p <0.05) when compared to the control group, reaching an average of 91.83% from day +1 to +29 and 95.26% from day +8 to +29 . All parameters of evaluation of reproduction (RI) and nutritional (IN) indices had significant differences (p <0.05), except for the weight of the kenogen, but the average effectiveness on reproductive efficiency was only 30.97%. The persistent efficacy of fipronil was also significant (p <0.05) and remained high for 3 weeks after treatment, with its averages 98.69%, 99.19% and 99.32% respectively for challenges +7, +14 and +21. This high efficiency made it impossible to statistically analyze reproductive indices by insufficient samples from engorged females in the treated group. Both therapeutic efficacy and residual efficacy showed values greater than 90%, enabling the use of fipronil in the strategic control of D. nitens, but not in an eradication program, since the study demonstrated, even if low, the recovery of engorged females in both effectiveness tests, in addition to not inhibiting reproductive efficiency.

MEMBROS DA BANCA:
Interno - 124.088.737-03 - DIEFREY RIBEIRO CAMPOS - UFRRJ
Interno - 1173660 - FABIO BARBOUR SCOTT
Externo à Instituição - LICIUS DE SA FREIRE - FIPERJ
Externa à Instituição - LILIAN CRISTINA DE SOUSA OLIVEIRA BATISTA CIRNE - CESVA