About Bots
The Botfly, or Gasterophilus, lays its eggs on the forelimbs, chest and head regions of horses between May and October and these can be seen as small yellow dots in the horse's coat.
Horses find the Botfly particularly annoying and this causes them to lick and bite themselves. Unfortunately this action stimulates the bot eggs to hatch and the larvae then burrow into the mucous membranes of lips, gums, cheeks and tongue of the horse. Although this does not appear to cause any discomfort to the horse, the larvae incubate for 3-4 weeks before migrating to the stomach where they grow and attach themselves to the stomach wall of the horse.
Large quantities of bot eggs in the stomach can cause loss of condition, a dry coat, increased temperature, restlessness, kicking at the belly and lack of appetite. This may be accompanied with intermittent diarrhoea or constipation. The larvae can cause gastritis, stomach ulcers and in severe cases perforation of the stomach causing fatal peritonitis.
The larvae remain in the stomach until the spring when they pass with the faeces, pupating on the ground to emerge as adult flies one or two months later to repeat the cycle.
In order to control Botfly infestation it is necessary to worm the horse regularly with a suitable wormer that will ensure that larvae in the stomach are killed and Ivermectin is highly effective against all stages of Bot fly larvae. Although the Bot is not a "worm" an increasing number of wormers are effective against Bot larvae infestation.
Bot eggs should be removed from the horse's coat daily either by hand requiring "pinching" the eggs off or using a Bot knife.
Turning horses out after dark and bringing in early in the morning or providing a darkened shelter will also help.
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