Efficacy of an oxibendazole-trichlorfon paste formulation against third stage larvae of Gasterophilus intestinalis and its safety in horses.

This study investigates the effectiveness and safety of a paste formulation composed of 14.3% Oxibendazole and 44% Trichlorfon in treating larvae of Gasterophilus Intestinalis (equine stomach bot fly) in ponies and horses.

About the Study

• The test compound, a paste formulation, included 14.3% Oxibendazole and 44% Trichlorfon. This combination was administered to 33 ponies and horses as a potential remedy against Gasterophilus Intestinalis, a type of parasitic bot fly larvae that commonly infest horses.
• The dosage applied was close to 10 mg and 30 mg per kilogram of body weight for Oxibendazole and Trichlorfon, respectively. This treatment is stated to work by terminating the third-stage larvae of Gasterophilus Intestinalis, the most destructive stage of the parasite.

Findings of the Study

• After the treatment, 25 out of the 33 animals administered the drug expelled between one and 82 third-stage larvae through their feces, which indicates the effectiveness of the drug in eliminating the parasites.
• Later, these animals were given a dose of 0.2 mg ivermectin per kg of body weight. Ivermectin is another commonly used anti-parasite compound in veterinary medicine. Following this treatment, six animals expelled between one and four parasites.
• The overall effectiveness of the combined Oxibendazole-Trichlorfon paste appeared to be quite high, averaging around 96.2%.
• Lastly, this drug combination was deemed safe as it was well-tolerated by 52 ponies and horses administered the indicated dose rate. Furthermore, the drug was administered at twice the dose rate to six other ponies, who also tolerated it without any noticeable side effects. Only instances of transient stool softening in several animals and mild colic symptoms in two horses were observed which can be deemed as minor side effects given the context and the efficacy of the drug.

Significance of the Research

• This research indicates the potential use of a paste comprising Oxibendazole and Trichlorfon as a safe and effective deworming agent for horses. With the average efficacy of 96.2%, this can be a potent treatment against third-stage larvae of Gasterophilus Intestinalis.
• This new treatment, being safe and effective, could hugely contribute to equine health and could potentially reduce instances of infestation, thereby increasing the quality of life for horses and reducing medical costs.