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Parasite Control
Internal parasites are silent killers.
They can cause extensive internal damage, and you may not even realize your animals
are heavily infected. At the very least, parasites can lower resistance, rob
the horse of valuable nutrients, and cause gastrointestinal irritation and unthriftiness.
At their worst, they can lead to colic, intestinal ruptures, and death.
In terms of management priorities, establishing an effective parasite control program
is probably second only to supplying the horse with clean, plentiful water and high
quality feed. It's that important!
Identifying The Enemy
There are more than 150 internal parasites that affect horses, including several
major species. Among the most common and troublesome are:
Large strongyles (bloodworms)
Small strongyles
Ascarids (roundworms)
Pinworms
Bots
Tapeworms
Threadworms
Lungworms
Any or all of these parasites can
be present in the horse at one time, but they may be at different stages in their
life cycles. This will influence the deworming program needed to combat them.
Also, keep in mind that some species can lay more than 200,000 eggs a day, so parasite
loads can escalate quickly.
Parasite Damage
Different parasites harm the horse in different ways. They can damage tissues
and vital organs, including the major blood vessels to the intestines, lungs, liver,
stomach, and intestines, as they migrate through the horse's system to complete
their life cycles. They can cause obstructions and ulcerations within the
horse's digestive tract, and they can also cause intense irritation as they lay
eggs, such as pinworms do.
Signs Of Parasitism
Contrary to popular belief, many horses that have dangerous parasite levels appear
to be perfectly healthy. From the outside they may be fat, sleek and shiny,
while on the inside the worms are doing irreparable damage. But in other horses,
especially young horses, parasites can take a visible toll. Signs such of
infestation might include:
- Dull, rough haircoat
- Lethargy or decreased stamina
- Weight loss
- Coughing and/or nasal discharge
- Tail rubbing and hair loss
- Resistance to the bit due to mouth lesions
- Colic
- Summer sores
- Depression
- Loss appetite
- Unthriftiness or loss of condition
- Diarrhea
Fecal Examinations
One of the most under-utilized tools
in an effective parasite control program is the fecal examination, which merely
involves taking two to three fresh fecal balls to your veterinarian for laboratory
analysis. This simple process can identify the specific parasites infecting
a horse. Rarely are the worms themselves visible in the manure. But
by counting the types and numbers of parasite eggs present in the fecal sample,
your veterinarian can recommend the right deworming agents to do the job.
Fecal eggs per gram counts also tell an owner about the degree of parasite infestation
on a farm or within a herd.
The fecal exam is a cost-effective
follow-up to deworming to determine whether the dewormer has worked. It's
good practice to do a fecal egg per gram count within two weeks after deworming.
The Importance Of Rotating Deworming Agents
Parasites can develop resistance
to many of the chemicals used to kill them.
After a period, the deworming agents may therefore simply become ineffective.
To prevent this, it’s important to rotate
classes of drugs used in your program.
Be sure that you don’t simply change brand names, however, since many products contain
the same drugs but under different labels.
Although some manufacturers claim that certain products do not require rotation,
a good safeguard is to do it anyway.
That way, there’s no question about resistance developing.
With opinions varying as to how often dewormers should rotate, it is recommended
to consult your veterinarian for guidance.
By utilizing broad-spectrum deworming
agents and rotating them as recommended by your veterinarian, you should be able
to rid your horse of most worms.
Methods Of Administration dewormers.
They are:
Oral paste syringe
Nasogastric tube (tubing)
Feed additive
All three methods are effective.
The key is that the deworming product must
be given in the proper dose at the proper time, and that it is fully consumed and
retained by the animal.
Deworming pastes and feed formulations
have come into widespread use because of convenience and ease of administration.They are a good choice as long as the
horse ingests the entire dose.(The
dose must be calculated based on the horse’s weight.)The problem is that some horses may find them unpalatable and spit them out.
Tube deworming, once the method of
choice, is still a highly effective means of controlling parasites.The advantage of administering dewormers via a nasogastric tube is that the
veterinarian can ensure the proper dose is delivered directly to the horse’s stomach. The disadvantage is that it causes the
animal temporary discomfort when it is passed through the nostrils and down the
esophagus into the stomach.Because
of the skill required to safely insert the tube, this method of deworming should
be performed only by a veterinarian.
Deworming Schedules
The best way to set up a deworming
schedule is to consult your veterinarian.
Horses at different ages and stages have varying needs concerning parasite control.For example, young foals are especially
susceptible to ascarid (roundworm) infestation, and may require deworming at thirty-day
intervals until they build some natural resistance.Older horses turned out on a large acreage might do well on a semiannual
schedule.And some owners may prefer
to have their horses on a continuous control program whereby the horse is given
a daily dose of dewormer through a feed additive.Climatic conditions and season of
year can also influence parasite levels.
Your veterinarian may recommend that you concentrate deworming efforts when your
horse’s exposure to parasites is at its peak.Other veterinarians may prefer that you deworm at regular intervals, such
as every sixty to ninety days.Still
others may recommend that you prevent parasitism with a daily dewormer.
In any case, the goal is to keep parasite loads to a minimum.
A Complete Management Program
Importantly, chemical control is
just one part of a total parasite control plan.Since parasites are primarily transferred through manure, good management
is also key.You should:
Pick up and dispose of manure droppings on a regular basis (at least twice weekly)
Mow and harrow pastures regularly to break up manure piles and expose parasite eggs and
larvae to the elements
Rotate
pastures by allowing other livestock, such as sheep or cattle, to graze them, thereby
interrupting the life cycles of equine parasites
Group
horses by age to reduce exposure to certain parasites and maximize the deworming
program geared to that group
Keep
the number of horses per acre to a minimum to prevent overgrazing and reduce the
fecal contamination per acre
Use a
feeder for hay and grain rather than feeding on the ground
Remove
bot eggs quickly and regularly from the horse’s haircoat to prevent ingestion
Rotate
deworming agents, not just brand names, to prevent chemical resistance
Consult
your veterinarian to set up an effective and regular deworming schedule
Summary
With the many safe, convenient products
available today, establishing an effective deworming program is easy.
Discuss a plan with your veterinarian and implement it without delay.
A good parasite control program will
go a long way toward maximizing your horse’s appearance, performance and comfort.\
The net result will be an animal that’s
as healthy on the inside as it appears on the outside.
This information is provided by the
American Association of Equine Practitioners.
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