Treatment and deworming
Treatment and deworming
TREATMENT AND CONTROL
OF INTERNAL PARASITES.
Last week we discussed the three more common groups of internal parasites. We spent time with them in the digestive tract of the horse, exploring where they hang out and what they did while there. Of course, no discussion of parasites is complete without the gory details of the damage they cause, and we discussed that.
This week we will discuss their life cycle outside the horse. The large, round worms are seen mostly in young horses. The adult worms within the intestine lay eggs that are passed in the hostís stool. These indestructible eggs will be on the ground, or on any surface making contact with the manure. It is while nosing around that the foal makes contact and ingests them. Once inside, the acidity, moisture, and temperature work together to convince the egg to hatch, continuing the life cycle.
The good news is that just about any dewormer will destroy these parasites. We must be alert, however, for intestinal problems the day or two after treatment in the heavily parasitized foal. If the foal has an unusually large abdomen and is a little unthrifty, we should be especially alert to the problem of large numbers of large worms physically migrating through the intestine.
The stomach and intestinal worms usually spread by ingestion of larva. Eggs are passed in the stool after being laid by the adults living inside the horse. These eggs lay on the ground, usually within the horse manure, until conditions are right. These eggs are easy to please, and just a moist warm environment will stimulate them to hatch. They crawl to the nearest blade of grass and crawl up to a junction. Moisture will accumulate there from the dew, etc. This is where the larva will stay until the sun comes out, then it will crawl up the stem to increase its chances of being ingested with the grass. Once ingested, they immediately start their journey through the body.
One exception to the above is the Strongyloides. This little pest is a common problem in the foal, causing diarrhea at a very early age. The foals ingest these as larva when they are nursing. The larva have moved to the udder from between the mareís legs and the area under the rectum. They are ready to go to work irritating the intestinal tract of the foal and stimulating increased activity, resulting in diarrhea.
We discussed the bots last week, including their life cycle. To control the larva on the legs, we only have to use a warm, rough, wet cloth or sponge and wipe down the legs where we see the yellow spots. To the larva, this simulates the lips and tongue of the horse, and will stimulate the larva to hatch. This procedure should be repeated every couple of days. If you have problems looking at all the yellow spots, they can be scraped off with special blocks or pumice stones.
Deworming for the above, with the exception of the bots, should follow a few basic rules:
Rotation of dewormer products [using different brands] is always a good precaution.
We use a dewormer administered by stomach tube, specifically because it is a product not available to the breeder over-the-counter.
This adds another product to the rotation, which helps to prevent immunity within the worm population.
Next week we will discuss specific products, and how to decide the frequency of treatment for your group of horses.
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