Deworming Horses 101

Deworming Horses 101 | Big Dee's Tack & Vet Supplies

Deworming guide

Have you ever been in a tack store staring at the wall of dewormers wondering “what should I give again“? Hopefully a savior (in the form of a store associate) arrives to tell you what to give. Then one arrives, but they are full of questions you just can’t remember the answers to! What did you de-worm your horse with last? , How often do you de-worm?, Have you had a fecal sample taken?  Since most of us have been there, here is an overview that we hope is helpful when planning your horses deworming schedule this year.

Let’s start with some basics –

What types of worms cause trouble?

Encrusted Small StrongylesMost susceptible are young and older horses. The larva can embed in the intestines. Large numbers of small strongyles can cause weight loss, colic, diarrhea and overall poor condition.

Ascarids (roundworms) – Dangerous to foals and horses under the age of two. Once ingested the larvae move through the veins into the liver, heart and lungs. Larvae in the lungs will eventually get swallowed to develop in the small intestine. Because the larvae migrate through the lungs a young horse could develop respiratory disease, have poor weight gain and colic.

Large Strongyles (bloodworms) – These worms can be dangerous to organs and can weaken abdominal artery walls. Common symptoms – diarrhea, weight loss and colic.

Pinworms – Not as dangerous as the other worms listed here – these worms typically cause itching around the horse’s rectum and tail.

Threadworms – Dangerous to foals and young horses. Foals can become infected by nursing from a mare with the larvae. They live in the intestinal tract. Common symptoms – diarrhea and weakness.

Bots In the warm seasons bot flies swarm around horses with the main purpose of finding a place on the horse to lay its eggs. After the eggs are laid – the horse can ingest them. Once inside the horse, they implant themselves in the mouth or intestines. While living in the intestines they can cause poor overall condition and mild colics.

Tapeworms – These are probably the least worrisome worm of them all. Tapeworms reside in the intestine and just live off of the food that comes to them. Mild colic and diarrhea are common symptoms of a horse carrying many tapeworms.

Now that we know about the worms… let’s find out how to treat them!

What types of dewormers are there?

Ivermectin Paste &  Praziquantel – For the removal & control of large and small strongyles, pinworms, hairworms, threadworms, stomach worms, lungworms, ascarids (roundworms) and bots.

Moxidectin Paste & Praziquantel – For the removal & control of large and small strongyles, ascarids (roundworms), pinworms, hairworms, stomach worms and bots.

Fenbendazole – For the treatment of large and small strongyles, ascarids (roundworms) and pinworms

Pyrantel Pamoate – For the removal and control of large/small strongyles, roundworms and pinworms

Daily Dewormers – Pryantel Tartate – Provides continuous protection against large and small strongyles, ascarids (roundworms) and pinworms.

Many veterinarians recommend fecal exams every three months. The exam will determine how much your horse sheds parasite eggs. Horses can range from heavy, to moderate to light shedders. Some horses have a high immunity to the parasites while others don’t. Horses that are in the pasture with other horses have a higher risk of becoming infected with roundworms and strongyles. A horse needs to ingest the eggs to become infected. Horses that are kept in well cleaned stalls are less likely to become infected. There are other factors as well – age, environment, climate, etc.

Your vet will most likely come up with a proper deworming program for you that will last a year. After a year, you will need to reevaluate and come up with an updated program.

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