1. H1.1 Horse Care H1.8 Parasite Control
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2. Parasite Control Overview
Life Cycle of a Worm
Common Internal Parasites
Effective Parasite Control Measures
De-Worming
Using a Paste Wormer
Parasite Control Introduction
Parasites are organisms which live in or on a host (i.e. horse) and gains nourishment from the host. That means that viruses, bacteria, fungi are all parasites however in this workbook worms will be covered.
Effective worming strategies and management practices will help to keep you horse and paddocks or pastures healthy.

3. Life Cycle of a Worm
Each type of worm will have a slightly different life cycle in regards to how long the process takes and where they will end up in the horse’s body however the overall cycle is the same.
Adult worms already present in the horse lay eggs which get passed out in the manure.
The contaminated manure is passed onto the pasture with the worm eggs
The eggs then hatch into larvae on the pasture
Whilst grazing the horse picks up and ingests the larvae which then migrates to wherever that particular type of worm inhabits in the horse’s body systems
The larvae mature into adult worms, which lay eggs and the whole process starts again.
The life cycle of a worm can be subject to seasons (climate, weather). Some worm eggs will only hatch under certain environmental circumstances (i.e. warm weather) or at a certain time of year.

4. Common Internal Parasites
The vast majority of horses have worms and there are a few different types, all of which will affect different body systems. Below are common types of internal parasites you will be worming against.
Strongles
There are large and small strongles and they are also referred to as redworms and bloodworms. These worms burrow into the walls of the blood vessels. Heavy burdens can cause death and they are also a common cause of colic.
Blood clots form from where the larvae have buried into artery walls, these blood clots then break away and can clog up arteries which can lead to the intestines or hind legs.
During infestations, these parasites may become visible in water troughs and in manure.
Thread worms
Most likely found inhabiting the small intestine of foals up to 6 months of age. They are transmitted to the foal through the mares milk. They are uncommon after that age.
Diarrhoea, dermatitis and weakness are signs of infestation and in severe cases death.
Strongles
(Redworm/bloodworm)
Threadworm

5. Common Internal Parasites (cont.)
Pin worms
Found in the large intestine, here they can cause ulceration, the eggs are released into the rectum and anus which causes irritation to the horse. This can be apparent from the horse rubbing its tail. The eggs are then transferred onto pasture or water.
Severe infestations can cause anorexia and nervousness. Chronic infections will lead to horses which are poor in appearance.
Pin Worms

6. Common Internal Parasites (cont.)
Bots
Bot Fly
Bot Eggs
Bots
There are bot eggs and bot flies. One leads to another. Bot flies lay bot eggs on the hairs on the horse. The eggs are small and yellowish in colour, the flies are large an sometimes look like bees. The horse ingests the larvae when it rubs against the eggs with its mouth. The larvae remain in the mouth for 1 month before migrating to the stomach where they can cause haemorrhage, intestinal blockage, ulcerations and perforation of the stomach. Here they will stay for 12 months living off tissue and blood. Then they are passed out in manure where they will pupate and emerge as flies and the process starts over.
Bot Knife

7. Common Internal Parasites (cont.)
Roundworms (ascarids)
Common in young horses they can cause coughs, rough hair, slow growth and pot bellies. Of course in large numbers they can cause death.
These worms are carried to the blood supply to the lungs where they break through blood vessels to migrate into the trachea. Here they are coughed up and swallowed again to end up in the small intestine, where they mature. Strangely enough this is where the process starts because to gain entry into the blood stream they first burrow through the intestinal wall
Onchocerca
The microfilariae (early larval stage) of Onchocerca are found just beneath the skin. They can invade the eye and cause blindness and the adults are found in the neck and flexor tendons. Heavy infestations can restrict movement.
They are spread through biting midges which transfer the microfilariae by biting an infected horse then biting a non infected horse.
Roundworm
(Ascarids)
Onchocerca
(Invading the eye)

8. Common Internal Parasites (cont.)
Tapeworms
Tapeworms
Tapeworms take up residence in the digestive tract. When the end of the worm fills with eggs, it separates and is expelled from the body in manure. They can cause colic, poor growth and lethargy
Most of the damage inflicted by worms is internal however there are some visible signs which may indicate an infestation.
Signs of worms or the need for worming may include:-
itchy tail
poor coat condition
loss of weight
poor weight gain
presence of worms in manure or water troughs (redworms)
summer sores
diarrhoea
lack of energy
hair loss
colic

9. Effective Parasite Control Measures
Pick up manure regularly
Within your management of your property or paddock there is some effective management practices you can do to help minimise worm populations. Small properties and paddocks are more likely to have higher populations due to high stocking rates in a small area (i.e. many horses on a small piece of land). This doesn’t mean the operator of the small property is negligent or irresponsible in their horse care, it is just that where there is a higher population of horses there is more likely to be a higher population of worms.
Cross-graze pasture

10. Effective Parasite Control Measures (cont.)
Other than regular worming schedules there are a few more things you can do to help control parasites.
Picking up and removing manure regularly (twice a week). Completely clearing a paddock of manure will reduce the number of eggs in the paddock therefore reduce numbers of reinfestation.
Prevent overgrazing by reducing stock numbers on pasture. More horses mean more manure which means higher contamination.
Keep feed off the ground. Put feed and hay into feeders.
Cross graze (to alternate grazing of paddocks between species) paddocks with sheep or cattle. By cross grazing it will interrupt the life cycle of equine parasites.
Spell (give the paddock a break from grazing) paddocks regularly. Mowing and harrowing pasture whilst giving the paddock a ‘rest’ will break up manure piles and expose eggs to the environmental elements.
Remove bots eggs from the horse’s coat. Knives are available designed specifically for this purpose.
Your veterinarian will be able to do faecal egg counts which will help you to be able to monitor the effectiveness of your worming program.
Feed horses off the ground
Avoid over grazing

11. De-Worming Measure the horse’s weight
There are many different worming products on the market. Worming compounds are available in paste or powder/granules form.
Pastes come in a plastic syringe and are inserted into the mouth over the back of the tongue. This type of compound can be brought from your local saddlery, produce or stockfeed store and is quick and fairly straight forward to deliver.
Powders or granules are mixed in with the horse’s daily feed. It is a less common method or delivering worming compounds. Some horses may sift the product out of the feed.
There is another method of delivering wormer and that is by stomach tube by your veterinarian. This method delivers the compound straight to the stomach and is used mostly for horses with heavy infestations. It should only be performed by a veterinarian.
You will need to rotate wormers regularly. This means choosing and alternating between wormers of different chemical compounds to ensure that the parasites don’t build up a resistance to one particular compound because they are always exposed to the same one, which will make the worming product ineffective. Some wormers will only treat certain parasites and at certain times of the year various parasite groups will pose a threat more than at other times of the year.
Over dosing with wormer to ‘be sure’ is not necessarily a good idea. It have serious health affects for the horse. Under dosing can lead to a build up in resistance to the product by the parasites, simular to the resistance mentioned when worming compounds/wormers aren’t rotated. Under dosing resistance is built up because the dosage of the chemical agent is not strong enough to kill the parasites.
Therefore it is important to establish the correct weight of the horse to be wormed (or de-wormed). This can be done without scales by using a weight tape.
Weight tapes usually have instructions on how to use them imprinted on the tape but to give you an overview you measure the length of the horse, from the point of the shoulder to the point of the buttock. The second measurement is taken from around the girth so the tape should lie just behind the wither and behind the elbow.
Then calculate the two measurements by:-
[Girth (cm) × Girth (cm) × Length (cm)] / 11,900 = Weight(kg)
[Girth (in) × Girth (in) × Length (in)] / 330 = Weight (lb)
It is important that the horse be standing still, on level ground and fairly square (the 4 hooves placed so that they would illustrate the 4 corners of a square or rectangle) to get an accurate measurement.
[Girth (cm) × Girth (cm) × Length (cm)] / 11,900 = Weight(kg) OR
[Girth (in) × Girth (in) × Length (in)] / 330 = Weight (lb)

12. De-Worming (cont.) Check the product label for advice when using on:-
There are some other factors which will influence the type or brand of worming product you use. Some wormers will be unsuitable to use on foals, pregnant and/or lactating mares and breeding stallions. It is a good idea to check the label on the product before purchasing or you can consult your veterinarian.
How often you worm your horses may depend a little upon your situation. A horses kept on large acreage by itself may require treatment less often than a horse kept in a smaller paddock or with numerous other horses. This is because the horse kept in the smaller area or with other horses will be exposed to worms in larger numbers.
Pregnant mares
Foals & lactating mares

13. Check the product label for advice when using on:-
De-Worming (cont.)
Check the product label for advice when using on:-
Breeding stallions
Weather will also play a part horses in climates where it is hot and humid may require worming every 6 weeks.
As a general rule horses which are kept on their own in a small paddock will require worming (de-worming) every 6 – 8 weeks.
Check the labelling on the worming product. The label will specify:-
how long it will stay active in the horse’s system before you need to de-worm again
what horses it is safe to use on (i.e.- whether it is suitable for pregnant mares etc)
what worms and parasites it works on
what chemical it contains (useful knowledge for when you are rotating wormers)
when to administer (i.e. before feeding or after feeding)
If in doubt consult your veterinarian.

14. Using a Paste Wormer How to administer a paste wormer:-
Restrain the horse with a halter and lead rope, if necessary you can have an assistant hold the horse
Measure the dosage required for that horse
If you have no assistant you will need to hold the lead rope whilst you stand to one side of the horse’s head
Insert your thumb into the corner of the horse’s lips. Remember there are no teeth in this area and by inserting a thumb or finger into this area will encourage the horse to open its mouth
Make sure the mouth is free from feed and grass. The best way to avoid this is not to worm immediately after feed times. If there is any food in the horse’s mouth it will mean that when you administer the wormer it will get onto the feed and the horse will spit it out resulting in the horse being under-dosed. Usually the horse will spit out any feed when you use your finger to in the corner of the lips to open the mouth. Do not attempt to remove feed from the mouth with your hand or fingers!
Insert the syringe into the corner of the mouth and aim it upwards towards the back of the tongue
Depress the syringe
Remove the syringe and raise the horse’s head. This is to help prevent the horse from spitting it out and encourage the horse to swallow
Finally release the horse
Dispose of the syringe as described by the labelling on the product
Some horses may be more difficult than others, if so handling the horse in a smaller yard can be effective in helping to control them.

15. After the Video Tutorial
View the Power Point Presentation and see if you can discuss each slide
View the Video Tutorial again, if necessary
Read the Workbook
Do the Homework/Extension Lesson
Complete the Online Quizzes
Complete the Practical Assessments
Join Phone Tutorials if available
Listen to Phone Tutorial Recordings

16. References Publication:- Author:- Websites:-
Feeding and Nutrition of Horses John Kohnke
Foot Steps Sally Hinton & Joan Ecclesshare
Storey’s Guide to Feeding Horses Melyni Worth
The BHS Veterinary Manual P. Stewart Hastie
Websites:-

17. References (cont.) Images:-
website.markjohnstonracing.co.uk/?page=10574

18. References (cont.) Images:- http://img.smartpak.com/product/15805.jpg