No abstract

The aim of this study was to determine the time required by different anthelmintic agents to reduce strongyle egg shedding in horses. Fifty horses were divided into five homogenous groups based on faecal egg counts (FECs). Treatment groups received either ivermectin; moxidectin; fenbendazole; piperazine; or no treatment (control group). Faecal examinations were performed 4, 8, 12, 18, 24, 36 and 48h after the anthelmintic treatment. After this period, faecal samples were taken every 24h over the next 12days and finally on alternate days (48-h intervals) for another 14days until the end of the experiment (28days post-treatment). The faecal egg count reduction (FECR) was calculated based on the post-treatment mean FECs in the controls and treated animals. Eggs were absent from the faecal examinations beginning at 72h and 4days, respectively, following treatment with moxidectin or ivermectin. Piperazine showed an FECR greater than 95% from 48h up to 9days post-treatment, with the highest FECR value recorded at 7days post-treatment (98.1%). However, the FECR was lower than 90% in the last two samplings (26 and 28days post-treatment). The febendazole group presented the lowest efficacy with FECR below 90% in all samplings. The faecal cultures showed that at the beginning of the trial, all of the groups presented with mixed infections and were predominantly composed of cyathostomins (92.8%), followed by Strongylus vulgaris (5.6%) and Triodontophorus serratus (1.6%). Only cyathostomin larvae were identified following treatment with fenbendazole or piperazine. In conclusion, horses in the present study had a segment of the cyathostomin population with resistance to fenbendazole and piperazine. The strongyle population was susceptible to macrocyclic lactones, with cessation in egg shedding three and four days after treatment with moxidectin and ivermectin, respectively.

The objective of this study was to analyze the effects of anthelmintic treatment and supplementation of post-weaning Nellore calves. The parasitism degree, hematological changes and animal performance were analyzed, as well as the financial viability. One hundred contemporary Nellore calves were used. Animals were divided into four groups: CS+AT: supplementation with concentrate and anthelmintic treatment; CS: supplementation with concentrate; PS+AT: protein mineral supplementation and anthelmintic treatment; PS: protein mineral supplementation. Coproparasitological, hematological, and cost examinations were performed, and productive performance was also evaluated. A completely randomized design was used. Animals that received CS+AT showed greater weight gain. In females, there was significant difference in egg counts per gram of feces only between the CS and PS+AT. In males, animals receiving CS+AT, CS, and PS+AT differ from those receiving PS. No significant effects were observed for total plasma protein, packed cell volume, and eosinophils count. Females which received PS+AT and males who received CS+AT showed higher profitability. This study concludes that effective anthelmintic use is still viable, with higher profitability associated with concentrated supplementation in males, and mineral protein supplementation in females. Male calves show better return over investment when compared to females, due to the higher market value and higher potential performance.

The prevalence of helminths in horses may vary, depending on climatic factors and host susceptibility. The objective of this study was to evaluate the seasonal dynamics of helminth infection in grazing horses, from October 2015 to September 2016. In total, 104 crossbred horses of different age groups, males and females in a single herd, participated in this study. Individual fecal samples were collected every 28 days for counting of eggs per gram of feces (EPG) and fecal cultures. The horses were evaluated individually for weight, body condition score (BCS) and clinical status. Climatic information relating to the farm was also collected. The categories most affected by helminths were foals and senior horses, with EPG averages of 1271.9 and 1186.5, respectively. The EPG averages for all animal categories together, in the four seasons were: 1042.1 spring; 1508.9 summer; 817.8 autumn; and 571.1 winter. Through the body condition evaluation, it was seen that senior animals presented the lowest BCS in all seasons. It was concluded that the season in which these animals were most affected by helminth infections was the summer and that the most susceptible categories were foals and senior horses.