Dermatological and parasitological evaluation of infestations with chewing lice (Werneckiella equi) on horses and treatment using imidacloprid.

This study investigates the presence of the chewing louse Werneckiella equi in horses, the associated dermatological symptoms, and the efficacy of a treatment using a 10% solution of imidacloprid. While many horses with lice showed symptoms, a significant proportion without lice also did. After treatment, all horses were free of live lice and exhibited significantly reduced symptoms regardless of their original lice count.

Research Context and Methodology

• The researchers aimed to examine the extent of lice infestations in horses caused by the chewing louse called Werneckiella (Damalinia) equi, which is seen worldwide. They also assessed the effectiveness of a lice treatment made with 10% imidacloprid.
• Two groups of horses were selected, all naturally infested with lice. The groups received double applications of the treatment, either 4 ml or 8 ml, on the first day and again on the 28th day. The study also included horses with dermatological signs but without lice.

Findings

• The results showed that over 40% of the horses tested positive for lice. Among these, over 80% displayed clinical dermatological signs, such as itching or skin lesions related to the lice infestation.
• Interestingly, about 65% of horses that did not have lice still showed clinical symptoms. This indicates that lice infestation is not the only cause of these dermatological conditions in horses.
• Two days after the treatment was given, the lice count reduced on horses from both treatment groups. By the 56th day, no live lice were seen on any of the animals in the study.
• The reduction of dermatological lesions was significant in both lice positive and negative horses after the treatment was provided (with a P value 0.050).

Conclusion

• In conclusion, the study observed a high frequency of lice infestation in horses and its associated dermatological signs. The treatment using 10% imidacloprid proved effective for lice elimination and for decreasing dermatological manifestations. The presence of dermatological signs in lice-negative horses suggests other possible causes for these symptoms.
• The results provide valuable insight into understanding the impact of lice infestation on horses and the efficacy of potential treatments, demonstrating that the treatment approach used in this study can potentially be utilised for effective control of lice in horses and the corresponding dermatological symptoms.