RESUMO
The effect of ethyl-4-bromophenyl carbamate on different Rhipicephalus microplus stages implanted in cattle was evaluated using the pen test with infestation chambers. Twelve steers were distributed into four groups (n = 3), each with four chambers (12 chambers per group), where approximately 1,000 R. microplus larvae were placed in each chamber. The chambers of the first group were sprayed with a solution of ethyl-4-bromophenyl carbamate (0.668 mg/mL) on day 2 post-infestation (PI) (exposed larvae). The chambers of the second group were sprayed with the same solution on day 8 PI (exposed nymphs), and the chambers of the third group were sprayed on day 16 PI (exposed adults) with the same solution. The chambers of the fourth group were used as controls. The percentages of engorged females, egg laying, egg production and egg hatching were evaluated in all groups. The percentage of cumulative reduction of hatched larvae was 98.3, 96.1 and 94.4% when larvae, nymph and adult stages were treated, respectively. The average cumulative reduction of hatched larvae, considering the three treated stages, was 96.3%, whereby the reproductive potential of this tick was drastically reduced. In conclusion, ethyl-4-bromophenyl carbamate acted as an ixodicide (lethal effect) when larval stages were sprayed and as a growth regulator when nymphal and adult stages were sprayed. The sum of these effects had a direct impact on the efficacy of the product in the pen test, and future studies will indicate the potential use of this product for tick control.
Assuntos
Acaricidas , Doenças dos Bovinos , Rhipicephalus , Infestações por Carrapato , Feminino , Bovinos , Animais , Carbamatos/farmacologia , Larva , Oviposição , Doenças dos Bovinos/prevenção & controle , Ninfa , Infestações por Carrapato/prevenção & controle , Infestações por Carrapato/veterinária , Acaricidas/farmacologiaRESUMO
The effect of experimental infection by Taenia hydatigena metacestodes on different productive parameters in sheep was evaluated. Seventeen male Columbia lambs distributed in three groups were used. The lambs of the first group (n = 5) were orally inoculated with 1000 T. hydatigena eggs (low dose). The lambs of the second group (n = 5) were inoculated orally with all the eggs of the last proglottid of an adult cestode (high dose). The lambs of the third group (n = 7) only received a placebo and were used as a control group. All lambs were humanely euthanized at week 13 postinfection, and carcass yield and conformation were evaluated. The infection rates of the lambs from the high-dose infected group and the low-dose infected group were 100% and 40%, respectively, with a mean of 2.4 ± 0.6 and 1 ± 0.7 metacestodes of T. hydatigena in the abdominal cavity, respectively. In a first multivariate study (MANOVA) considering the under the curve (AUC) values of body condition, weight gain, and feed consumption, as well as the final feed conversion values, showed a highly significant (p < 0.0001) group effect (high dose/low dose/uninfected). In a second multivariate study (MANOVA) considering the AUC values of eosinophils blood count, packed cell volume and alkaline phosphatase showed a highly significant (p < 0.0001) group effect (high dose/low dose/uninfected). The increase in serum ALP is a consequence of liver damage that had a strong negative correlation (r = -0.63, p < 0.007) with the body condition of the lambs. Despite these findings, we did not observe obvious clinical manifestations in any of the infected lambs. In general, no differences (p > 0.1) were observed between the lambs of the control group and the lambs of the low-dose infected group in the parameters evaluated. The results of this study show that the infection of T. hydatigena metacestodes subclinically produces a decrease in productive efficiency, alterations of some hematological and biochemical values, and a slight deterioration in the general appearance of the infected lambs. The above aspects are rarely detected by most farmers, but they have a negative impact on the productivity of infected lambs.
Assuntos
Doenças dos Ovinos , Taenia , Ovinos , Animais , Masculino , Doenças dos Ovinos/epidemiologia , Contagem de Leucócitos , HematócritoRESUMO
The acute oral and dermal toxicity of two new ethyl-carbamates (ethyl-4-bromophenyl-carbamate and ethyl-4-chlorophenyl-carbamate) with ixodicide activity was determined in rats. The oral LD50 of each carbamate was 300 to 2000 mg/kg, and the dermal LD50 of each carbamate was >5000 mg/kg. Clinically, the surviving rats that had received oral doses of each carbamate showed decreased weight gain (P < 0.05) and had slight nervous system manifestations. These clinical signs were evident from the 300 mg/kg dose and were reversible, whereas the 2000 mg/kg dose caused severe damage and either caused their death or was motive for euthanasia. At necropsy, these rats had dilated stomachs and cecums with diffuse congestion, as well as moderate congestion of the liver. Histologically, the liver showed slight degenerative lesions, binucleated hepatocytes, focal coagulative necrosis, and congestion areas; the severity of the lesions increased with dosage. Furthermore, an slight increase in gamma-glutamyltransferase, lactate dehydrogenase, and creatinine was observed in the plasma. The dermal application of the maximum dose (5000 mg/kg) of each carbamate did not cause clinical manifestations or liver and skin alterations. This finding demonstrates that the carbamates under study have a low oral hazard and low acute dermal toxicity.
Assuntos
Rhipicephalus/efeitos dos fármacos , Pele/efeitos dos fármacos , Uretana/farmacologia , Administração Oral , Animais , Creatinina/sangue , Fígado/efeitos dos fármacos , Masculino , Ratos , Uretana/análogos & derivados , Uretana/toxicidadeRESUMO
Female and male Wistar rats were used to determine the subchronic oral toxicities of two new ethyl-carbamates with ixodicidal activities (ethyl-4-bromphenyl-carbamate and ethyl-4-chlorphenyl-carbamate). The evaluated carbamates were administered in the drinking water (12.5, 25 and 50 mg/kg/day) for 90 days. Exposure to the evaluated carbamates did not cause mortality or clinical signs and did not affect food consumption or weight gain. However, exposure to these carbamates produced alterations in water consumption, hematocrit, percentages of reticulocytes, plasma proteins, some biochemical parameters (aspartate aminotransferase, gamma-glutamyl transpeptidase, cholinesterase, and creatinine activities), thiobarbituric acid reactive substances, and the relative weight of the spleen. Histologically, slight pathological alterations were found in the liver that were consistent with the observed biochemical alterations. The nonobserved adverse effect levels (NOAELs) of the evaluated carbamates were 12.5 mg/kg/day for both the female and male rats. The low severity and reversibility of the majority of the observed alterations suggest that the evaluated carbamates have low subchronic toxicity.