Parasites & De-Worming

Parasites . Small Redworm (small strongyles)- these absorb themselves into the

gut wall. They are thin and up to 2.5cm long, and can range in color from white to red. Small redworm larvae are picked up through natural grazing.

Large Redworm (also of the Strongyles family and often called "blood worms") – These affect horses because of the migrating larval stage that damages the lining of the arteries. Most commonly seen in younger horses, these are also most often responsible for deaths if left untreated for any length of time. The are approximately 1/2inch - 2inches in length.

Tapeworms - these are present, in the majority of horses and can grow to be 3ft long. They wrap themselves around the gut, causing damage to the bowel, intestine and digestive tract. Tapeworm can affect horses at any time during the year.

Roundworms - these can be over a foot long and look like white or cream garden worms. They are often found in young horses who have not previously been treated. Most horses outgrow their susceptibility to these parasites by age 4-5.

Bots - these are the larvae of the Bot Fly. Tiny white eggs are laid on the horses coat (mainly neck, shoulders and leg areas) in early summer and are ingested by the horse when he licks his coat. The eggs can be removed by carefully scraping off with a Bot knife but routine oral worming will help to eradicate these larvae even if the horse ingests them.

Pinworms- Pinworm eggs are picked up by horses from contaminated feed, water, or bedding. These worms are irritating, causing the horse to rub its tail, resulting in hair loss and sometimes injury to the tail and rump.

Does my horse have worms? Horses that may have worms may have a

dull and unkempt looking coat, they might look thin but have a big hay belly, and they probably will have a big appetite but show no sign of weight gain.

A horse showing symptoms of having internal parasites.

A healthy, normal horse.

How to get rid of parasites Worms and parasites like warm, wet climates,

so minimizing turnout in wet, humid weather can help cut down on parasites infesting horses.

Cleaning paddocks regularly cuts down on the risk of your horse contracting parasites from another horse’s manure.

Having a de-worming schedule that everyone follows at your barn is a must.

When de-worming, make sure everyone at your barn de-worms at the same time to maximize effectiveness.

Fenbendazole-Based Wormers

Effective Against: Redworms, Pinworms, Roundworms,

Stomach hair worms, Large-mouthed stomach wormsFenbendazole is an extremely safe wormer, able to withstand overdoses of 100-200 times the standard dose without causing harm to your horse. For this reason

Fenbendazole is often used to clear immature parasites (which are particularly resistant to wormers due to their slower metabolism) from a horse by applying a dose twice a day for five days.

The most popular Fenbendazole-based wormer on the market is Safe-Guard.

Oxibendazole-Based Wormers

Effective Against:

Large roundwormsLarge strongylesPinwormsThreadwormsWhereas Oxibendazole may not target as many

parasites as others, its success rate against the above listed parasites is very impressive: 97 – 100% effective! In addition Oxibendazole is a safe wormer, able to withstand overdoses up to 60 times the standard dose without causing harm to your horse.

The most popular Oxibendazole-based wormer on the market is Anthelcide EQ.

Ivermectin-Based Wormers

Effective Against:

RedwormsPinwormsRoundwormsLungwormsStomach hair wormsLarge-mouthed stomach wormsNeck and intestinal threadwormsBots As you can see, Ivermectin is one of the most effective and well-

rounded wormers available, though as with all wormers it does have its weaknesses since it is ineffective against small encysted strongyle and tapeworms. A very safe wormer, Ivermectin can be given in doses up to 60 times the standard dose without causing harm to your horse.

The most popular Ivermectin-based wormers are Zimecterin and Equimectrin.

Praziquantel WormersEffective Against:

RoundwormsTapewormsPraziquantel is not effective against many

types of parasites, but it has been shown to target the above parasites very effectively when paired together with Ivermectin. As such, Praziquantel-Ivermectin blends are available in the forms of Zimecterin Gold and Equimax. These blends should be included in any rotation schedule as they are extremely effective.

Moxidectin-Based Wormers

Effective Against:

Encysted small strongyle larvaeBot fly larvaeMoxidectin has been the subject of controversy and for

good reason. It is the only horse wormer that is capable of killing the above larvae in a single dose, which is a very impressive feat. Its liability is that the overdose tolerance threshold is far less than other wormers; 5 times the standard dose can cause significant damage to your horse.

Whereas it may be difficult to give an adult horse an overdose 5 times the standard dose, it's extremely easy to make this mistake when worming a foal. As such, at no time would I recommend using this wormer on foals or weakened horses.

The most popular Moxidectin-based wormer is Quest.

Pyrantel Pamoate-based Wormers

Effective Against:

RedwormsPinwormsRoundwormsIntestinal ThreadwormsTapewormsNote that although tapeworms are listed above,

Pyrantel Pamoate will not prove terribly effective against them unless a double dose is applied. Pyrantel Pamoate wormers are safe for horses up to 20 times the standard dose.

The most popular Pyrantel Pamoate-based wormers are Strongid and Exodus.

De-worming schedule Vets recommend you de-worm your horse every two

months, rotating the types of de-wormer each month.

Rotation Deworming Schedule:

TIME OF YEARJanuary/February

March/April May/June July/Aug Sept/OctoberNovember/December

ROTATION 1 2 3 4 5 6

COMPOUND 

Pyrantel 

Benzimidazole 

Ivermectin 

Pyrantel 

Benzimidazole 

Ivermectin 

PRODUCT

Strongid Paste Safe-Guard Paste

Zimecterin Paste

Strongid Paste Safe-Guard Paste

Zimecterin Paste

Agri-Mectin Paste