27/10/2022
Bot fly season is here again
Gasterophilus intestinalis, also known as horse bot fly, is a species of insect of the family Oestridae, and is found worldwide. The adults, which have a skinny bumblebee-like appearance, are prominently active in the summer. G. intestinalis is primarily a parasite of horses, mules and donkeys.
The best treatment is of course prevention, which can be done with the use of various fly rugs, masks and sprays, as well as keeping stables and turnout clear of faeces, and providing a well balanced, species appropriate diet to support gut function. However sometimes you need to take stronger measures.
The eggs of the bot fly are typically found on the legs, chest, and stomach of the horse - anywhere they might chew at and be indigested. Although they can be found anywhere on the body. They are typically easier to spot on darker horses, but that doesn't mean they aren't present on lighter coloured horses
One of the most effective ways to tackle this problem is with a specialised bot knife. Usually slightly curved and serated, this tool can be used to swipe down with the lay of the hair to remove the eggs. Usually the knives have a short edge that can be used to get around any joints, chestnuts etc.
On top of this, a robust deworming regime can help take care of internal infestation. Typically ivermectin is used in the Spring and Autumn. Bot fly larvae cannot be detected with typical faecal screening.
