Horse Worms Life Cycle

The round worms life cycle :

Roundworms - generally affect young horses much more than older horses and there are several reasons for this higher rate of infection in young horses and more specificially 2 year olds.

Firstly foals and yearlings don't seem to be as particular about where or what they eat and they have a tendency to eat in areas where the number of round worm eggs may be greater.

It also appears that as a horse gets older it developes some immunity to the eggs or larva as they migrate through the tissues and that keeps them from becoming adult worms in the intestines.

Roundworm eggs can remain dormant for many years in the soil and can withstand great variations in temperature, which can be well below freezing for long periods of time, or very hot and still not kill the larvae inside the eggs.

The adults look very much like some of their close relatives, earth worms, they can grow to 5 inches or nearly 20 inches in length and are generally white to light grayish blue in color. They are usually described as looking like spaghetti and can cause the young horse to appear mal-nourished (rough hair coat and pot bellied). The larva are often responsible for fairly severe respiratory problems in weanlings and yearlings as they migrate through the lungs. Large numbers of these worms can also cause impaction colic in young horses.

The blood worms life cycle :

Bloodworms - Strongyles are responsible for the most damage done to horses by parasites. There are over 34 species of strongyles divided basically into 2 groups. The large and the small.

The large strongyle group has been the most damaging but the education of horse owners about the effects of internal parasites over the last 50 years, plus the development of new and more effective wormers has greatly reduced the harmful effects that strongyles have within the equine industry.

However, the prolific nature of the strongyle worms has allowed them to withstand the effects of these new worming medications.

Some horses pass as many as 5000 strongyle eggs per gram of stool and a drop of dew taken from a blade of grass in an equine pasture may contain as many as 100 dormant larvae.

Studies have also indicated that 80%-90% of colics in horses are caused by strongyles. Both large and small strongyles have been proven to cause colic. The larval stages of large strongyles migrate through many tissues in the body of the horse, such as the liver, arteries, and intestinal lining. Small strongyle larvae excyst in the lining of the intestine and cause colic when they exist in large numbers.

The Bot fly and its worms life cycle :

Bot flys infect horses in large parts of the country.

Bots have a varied and interesting life cycle and the adults resemble a honey bee.

The larvae in the horses stomach look similar to many free living grubs.

The larvae attach themselves to the lining of the stomach and can cause a very small ulcer.

When there is a heavy infection and a great many larvae present then the individual ulcers can join and form one large ulcer.

If the resulting ulcer is large enough it can cause colic.

The tape worms life cycle :

Tapeworms are generally not thought to be much of a problem to horses.

However, in the last few years there seems to have been an increase in the number of horses being infected with tapeworms and. normal deworming medications are generally not very effective at eliminating these worms.

Therefore, in areas where tapeworms are known to be exist, special deworming programmes and specific wormers must be used to specifically control tapeworm.

Fortunately at present tapeworms do not cause horses a great amount of difficulty.

However, in certain situations the worm can cause colic and determined efforts should be made to control them.

The pin worms life cycle :

Pin worms - when you hear someone say "My horse must have worms, it's rubbing it’s tail" then pin worms are usually the main culprit .

The glue that the adult female pinworm uses to attach her eggs to the horses external rectal tissue causes severe irritation to the horse.

This irritation is a major cause of tail rubbing.

However, due to major improvements in recent worming medications and the modern overall cleanliness of todays stables and yards pinworm problems have been greatly reduced.