The Control of Parasites in Horses with Techniques That Have Evolved from Human Demands.

The control of Parasites in Horses with techniques that have evolved from human demands.

A parasite is an organism that makes use of other animals as a home or source of food. They are a part of the natural world just as much as any other animal is and all animals host a variety of parasites that live on or in them. Some parasites are harmless i.e. good bacteria whilst others can cause serious disease leading to death, therefore they need to be removed for the host's well being. (Reference 1)

A specific example of this is the control of parasitic worms in horses. There are many kinds of "parasitic worms" but the name often refers to and "is commonly used, for the various worms (scientifically known as nematodes) that live in animals, mainly in the stomach and intestines". -Parasites and horses, NZ equine research, Page 5

These worms complete their life cycle within the equine host; being ingested as eggs, using nutrients engulfed from the intestines for completion of growth and then, after breeding, eggs are excreted through the faeces to begin the cycle again.

So why worm? We worm to keep an essentially expensive and often loved animal safe. The horse industry is worth millions to New Zealand each year, both form industry such as Horse Racing and as a leisure activity. "Racing generates more than $1.4 billion in economic activity each year and creates the equivalent of 18,300 full-time jobs. More than 40,000 people derive their livelihoods from the New Zealand racing industry"- http://en.wikipedia.org/wiki/New_Zealand_Racing_Board (Reference 4)

Sales exports of horses, from New Zealand, alone generate more than $120 million each year. By controlling worms, you decrease the ill health created by loss of nutrients which can result in increased food bills, increased vet bills, poor sporting performance and even death (Reference 8).

The recognised need to control parasitic worms has been around for centuries. There are a variety of techniques to remove parasitic worms from a host; some that have evolved through natural adaptations and some that are the result of scientific research. Natural techniques such as harrowing and cross- grazing have historically proven effects however these are not enough alone, especially as land is more intensively grazed and horses are kept in more confined communities. Harrowing involves the breaking and distribution of manure which is most effective when done so in hot climates, as this exposes the eggs to the sun which kills them, however "the climate in New Zealand is not suitable for this method, which could actually lead to increased pasture contamination and therefore is not recommended" - Massey University, Parasite control, Page 1 (Reference 5). Cross- grazing is a method in which another animal is used to "clean up" the paddocks after. i.e. Some parasites of horses do not effect cattle or sheep therefore when they graze after, the parasites are unable to survive within their intestines resulting in an elimination the reproduction cycle. However there are some exceptions of worms, which is why this method is unreliable and dependent on the parasitic cycle present at the time. (Reference 5 & 6)

This is why scientifically based man- made remedies are required as they are more effective. Each wormer (drug) acts