Do combinations of fipronil, eugenol and carvacrol have synergistic effects against Rhipicephalus sanguineus?

The tick Rhipicephalus sanguineus is one of the main ectoparasites that affects dogs, causing direct and indirect damage to parasitized animals. Currently, infestation control is mainly carried out by using synthetic acaricidal drugs. However, a decrease in efficacy and an increase in resistance to the main therapeutic protocols against tick infestations have been increasingly reported and confirmed, a factor that has driven research into the potential acaricide activity of natural compounds, including in association with synthetic molecules. The aim of this work was to evaluate whether the combinations of fipronil (FIP) and eugenol (EUG), FIP and carvacrol (CAR), and EUG and CAR would have synergistic effects against immature and unfed adult stages of R. sanguineus through in vitro bioassays. Bioassays were carried out using the larval packet test (FAO 2004) adapted for nymphs and adults. The synergistic activity was explored by combining each solution, based on the estimated LC50, in a 1:1 ratio (FIP: EUG, FIP: CAR and EUG: CAR). CompuSyn software was used to evaluate the various pairwise combinations of FIP, EUG and CAR, checking if there was synergism or antagonism between them. FIP and EUG and FIP and CAR showed combination index (CIn) values above 1.45, indicating antagonism. The synergistic activity between EUG and CAR was verified against all unfed phases of R. sanguineus, since the CIn was below 0.70, a value that indicates synergism. The combination of fipronil with either eugenol or carvacrol presented antagonistic effects against R. sanguineus larvae. On the other hand, carvacrol and eugenol had excellent pharmacological synergism against all tick stages with mortality values in the range of 80 to 100%, including the adult stage, which is less susceptible than immature stages.

Pyothorax caused by Nocardia sp. in a cat - Case report.

Nocardiosis is an infection caused by ubiquitous opportunistic bacteria and is rare in felines. In retrospective studies of the infection in the species, pyothorax was found in only about 5% of the cases described, with the most frequent forms being cutaneous and subcutaneous. This report describes Nocardia spp. as an etiologic agent of pyothorax in a feline leukemia virus (FeLV)-positive female cat. A 10-year-old female mixed-breed cat, positive for FeLV, with chronic kidney disease IRIS stage 2, was examined with a severe dyspneic onset, suspected of pleural effusion. It also had skin lesions in the interscapular region. The patient underwent thoracentesis, and a dense, creamy, fetid, and flocculated liquid was collected. Radiography was performed after draining the pleural fluid, which showed images suggestive of atelectasis of the left lung lobes and pneumonia. The collected material was sent for analysis, which found that it was a septic exudate. In addition, it was referred for bacterial culture in a special medium due to suspicion of nocardiosis. Long-term treatment with amoxicillin + clavulanic acid resolved the clinical case.

A nocardiose é uma infecção causada por bactérias oportunistas ubíquas e é rara em gatos. Em estudos retrospectivos da infecção na espécie, o piotórax foi encontrado em apenas cerca de 5% dos casos descritos, sendo as formas mais frequentes a cutânea e a subcutânea. Este relato descreve Nocardia spp. como agente etiológico do piotórax em um gato vírus da leucemia felina (FeLV)-positivo. Um gato mestiço de 10 anos de idade, positivo para o FeLV, com doença renal crônica IRIS estágio 2, foi examinado com dispneia grave, com suspeita de derrame pleural. Apresentava lesões cutâneas na região dorsal entre as escápulas. Após sedação, tricotomia e antissepsia, o paciente foi submetido à toracocentese e coletado líquido denso, cremoso, fétido e floculado. A radiografia foi realizada após drenagem do líquido pleural, que mostrou imagens sugestivas de atelectasia dos lobos pulmonares esquerdos e pneumonia. O material coletado foi encaminhado para análise, que constatou tratar-se de exsudato séptico. Além disso, foi encaminhado para cultura bacteriana em meio especial por suspeita de nocardiose. O tratamento prolongado com amoxicilina + ácido clavulânico foi suficiente para a resolução do caso clínico.

Fluazuron orally administered to guinea pigs: pharmacokinetic and efficacy against Amblyomma sculptum.

BACKGROUND: Brazilian spotted fever (BSF), the most lethal tick-borne disease in the Western Hemisphere, is caused by the bacterium Rickettsia rickettsii and transmitted by the bite of Amblyomma sculptum. Capybaras are considered primary hosts of this tick and amplifier hosts of R. rickettsii, generating new infected lineages of A. sculptum in BSF-endemic areas. To define a possible treatment regimen for controlling the tick A. sculptum in capybaras, the aim of this study was to establish an effective fluazuron (FLU) dose to control A. sculptum larvae in artificially infested guinea pigs. METHODS: In Study I (pharmacokinetic and pharmacodynamic analysis), 24 guinea pigs were divided into four equal groups: control group (CG; untreated) and treated groups receiving FLU administered by gavage in three doses: G1-1 mg/kg, G2-5 mg/kg and G3-10 mg/kg, once a day for 15 days (d0 to d + 14). Blood samples were collected from the animals of the treated groups before and at d + 1, + 2, + 4, + 7, + 15 and + 21. The guinea pigs were artificially infested at d + 7 with A. sculptum larvae, and specimens were recovered at d + 11 to d + 14 and kept in a climatized chamber for 14 days. In Study II (evaluation of pharmacokinetic parameters), one group of eight animals received FLU administered by gavage in a single dose of 10 mg/kg, and blood samples were collected before and on day 0 (8 h after treatment), + 1, + 4, + 7, + 15, + 21 and + 28 after single FLU administration. FLU was analyzed in plasma samples by high-performance liquid chromatography with ultraviolet detection. RESULTS: FLU plasma concentrations increased quickly, indicating rapid absorption, and decreased slowly. Some larvae from all treated groups exhibited morphological and behavioral changes. FLU interfered in molting, and the efficacy obtained was 100% for all treated groups. CONCLUSIONS: The results offer promising perspectives for the development of a palatable feed cube containing FLU for free-living capybaras to control A. sculptum and also to prevent BSF in areas where capybaras have been shown to play a primary role.