There are three groups of internal parasite which have the ability to damage the gut and cause disease in the horse in Guernsey. The information below will hopefully explain the importance of developing a sound worming regime, using the best products at the correct time.
Roundworms come in many different forms but to simplify the situation, in the adult, Guernsey field grazed horse, the group known as cyathostomes (red worms) are the principle problem. They are grazed off the pasture as microscopical larvae which bury their way through the intestines and over many months migrate around certain organs of the body and the arteries of the intestines, depending on the worm type. They then return to the wall of the intestine where they live for a while (encysted) before bursting out into the gut to form adult worms which produce eggs causing further contamination of your pasture. Land which has been grazed by donkeys at some point over the preceding few years may be contaminated with lungworms. These parasites appear to be unable to complete their life cycle in the horse but the larval form migrates to the lungs where it can develop into a ‘foreign body type pneumonia’.
There is increasing evidence that the horse tapeworm, Anoplocephala, which live at the iliocaecal junction (near where your appendix is sited) of the horse, can cause major disease such as repeated colic. Tapeworms have an interesting life cycle which cannot be completed without an ‘intermediate host’. In the case of Anoplocephala, this is the harvest mite found on the pasture during the summer and autumn and to a lesser degree in hay. The horse eats the mite, the tapeworm is liberated in an immature form and over many weeks changes to an adult tapeworm.
The Bot fly, Gasterophilus, is the fast moving, bee like fly which buzzes around stables and fields in the summer months. Eggs are laid by the fly on the horse which ingests them whilst grooming itself. The eggs hatch by this process, the larvae burry their way through the back of the tongue and all the way down to the stomach, where they erupt and form masses of large grubs which cling to the stomach wall. There is still debate on how serious a disease risk they are but some forms of digestive upset and colic are blamed on them. The adult flies can make horses bolt.
There are many different horse worming products on the market. Many have worm resistance developing and others are not very effective. New worm products and formulations over the past couple of years allows easy and thorough worming of your horse.
This is a new wormer on the market in the form of an oral dosing syringe containing Moxidectin (effective against encysted redworm larval forms as well as the adult roundworm, lungworm and bots) and Prazequantel (against tapeworms) . Ideally it is given directly into the mouth but it can also be put in a little ‘tasty’ food. Promax has no known parasite resistance and delays the reappearance of eggs for over three months.
Your worm control will only be as good as your management. Picking up droppings in the field, daily, not allowing the ground to go ‘horse-sour’ and keeping noxious weeds at bay are essential. Rotating cattle or sheep after the horses have grazed the land and ploughing, liming and reseeding every few years will help prevent worm infestation on the pasture. Any new horse introduced to a yard should be wormed with Equest and kept in a box or restricted paddock for a couple of days with collection and disposal of droppings prior to any introduction to communally grazed pasture. This particularly applies to horses brought in from outside the Island.
We advise the following worming protocol
Remember to either keep the horse in for 24hours after worming or to make sure that ALL droppings are picked up ASAP. No worm product kills 100% of worms, hence the necessity to follow the above protocol. Equest has no major environmental issues that may occur with ivermectin wormers.