Horses are susceptible to a variety of parasites. It is crucial for the health of your horse to put a worming program in place to avoid the harmful effects of a worm burden on your horse. While horses can get several types of worms, we will focus on lungworms, what they are and how to avoid them.
What Are Lungworms
The lungworm is a type of roundworm, officially called Dictyocaulus arnfieldi. One of the rarer types of worms to affect horses as its preferred host is the donkey. A Donkey can live with lungworm without showing any signs. The donkey puts the horse at the most risk for lungworm infection if they share grazing land.
When a horse becomes infected with lungworm it can cause a respiratory infection. This infection can sometimes be severe.
How Do Horses Get Lungworm
Horses get lungworms by grazing on infected pasture. The larvae then move through the intestinal walls and migrate to the lungs to lay eggs. This triggers the cough, which pushes the eggs into the windpipe, so the horse swallows them. They then pass from the infected animal through its feces, and the cycle goes on.
This whole process can take as little as a week. Within a few days, the eggs from the poo can hatch into larvae and re-infect the animal.
Since donkeys are the preferred host of the lungworm, they are the most likely culprit if your horse becomes infected. That is if your horse shares grazing land with donkeys.
Signs Of Lungworm Infection In Horses
An infected horse can have mild symptoms such as moderate coughing to something more serious, such as bronchitis or pneumonia. The horse can also lose condition, such a losing weight, and have a dull coat. Older and weaker horses can suffer more severe symptoms, while foals might not show any signs at all.
When a horse gets bronchitis from lungworm, it is often accompanied by pneumonia. These horses can also have secondary bacterial infections and pulmonary edema. Mucus production increases, which can lead to difficulty in breathing. Severe infection is serious, especially in foals, as it can block airways and cause death.
Diagnosis Of Lungworm In Horses
If you suspect lungworm, it is best to consult a vet. The vet will carry out a series of procedures to confirm a diagnosis. First, they will ask you about your horse’s living conditions. They will ask if your horse shares grazing with Donkeys or if the pasture is particularly wet.
One step will be to carry out a fecal sedimentation test and microscope evaluation. This is sometimes not conclusive, as an infected horse does not always pass lungworm eggs. The vet may also carry out an endoscopy to examine the airways and take X-rays. They may also look for eggs in the trachea by carrying out a Bronchoscopy.
Avoiding Lungworms In Horses
Even though donkeys are the main risk for spreading lungworm to horses, it does not mean they cannot share grazing land. With careful pasture management and a good worming program in place, these two equines can live happily side by side.
#1. Poo Picking
The easiest and most important way of avoiding lungworms in horses is regular poo picking of their pasture. This is because the eggs of the worms pass from the infected equine through its feces. The larvae from these eggs then climb up the grass, which the horse ingests.
By poo picking regularly, you break the lifecycle of the worm. It can’t hatch and climb the grass to infect the horse. This should be done at least twice a week.
#2. Don’t Overgraze
Another way to prevent lungworm is to avoid too many equines on the pasture. This situation will increase the possible infected areas when the horse or donkey poos increases the risk of contamination. Ideally, you should limit it to two animals per acre.
#3. Rest Your Pasture
Always rest your pasture for three to six months of the year. If the larvae aren’t ingested, they will die. Frost can also kill off a good portion of worm larvae. However, neither of these management rules will completely eliminate pasture contamination but will significantly help you reduce the risks.
#4. Cross Grazing
Cross graze your pasture with sheep. Sheep will clean the grass of lungworm before putting horses back in the pasture. However, sheep are still susceptible to lungworm infection, so they will need their own worming program.
#5. Harrow Your Pasture At The Right Time
The best time to harrow your pasture is during a spell of the hottest days of the summer, as the sun will help kill the larvae. Harrowing spreads the larvae around the pasture. So if you do this during the rest of the year, you are only making the contamination worse.
#6. Isolate New Horses
If possible, keep any new horse or donkey that comes onto your property in its own area until you carry a fecal egg count and appropriate worming. This prevents any horses with a high worm burden from contaminating your pasture.
#7. Put A Worming Program In Place.
Carry out regular fecal tests to check egg counts for both horses and donkeys on your property. This should be done every three months. Keep in mind that it is common for lungworm egg levels in feces to be low. Also, if you are testing for all types of worms, which you should, the tapeworm is only detectable using a saliva test.
Treating Horses And Donkeys For Lungworms
In addition to good pasture management and a solid worming program, it is still possible for your horse to get infected with lungworm. Two different wormers will help treat the infection; these are ivermectin and moxidectin. If you treat a donkey, check with the vet which ivermectin and moxidectin wormers are safe for them, as not all of them are.
When you treat the horse, take it off the pasture to a stable where you can monitor for any ill effects and prevent the shedding of eggs. Foals should not be wormed with ivermectin, and neither foals nor young horses with moxidectin.
Conclusion
The best way of avoiding lungworms in horses is prevention. Keep your pastures clean, keep your herds ‘closed’, and manage a good worming program. If you are unsure what type of program to put in place, talk to your vet, especially if you also have donkeys. With careful management, you can successfully avoid lungworms and keep horses with donkeys happily.
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