Types of wormer

Not only are wormers known by a variety of brand names, but their active ingredients, even if different, may belong to the same group. Trade names may change and new wormers are constantly being marketed, so it is helpful to make yourself aware of the active ingredients in each.

The active ingredients in wormers can be divided into four different chemical groups: macrocyclic lactones (ivermectin and moxidectin), benzimidazoles (fenbendazole and mebendazole), pyrantel embonates and praziquantel.

Macrocyclic lactones treat bots, small redworms, large redworms and lungworms. Benzimidazoles treat roundworms, large redworms and small redworms. Pyrantel embonates treat large roundworms, large redworms, small redworms, seatworms/pinworms and tapeworms (all species); and Praziquantels treat all three species of tapeworm. Products based solely on Praziquantel do have a role to play in tapeworm control but must be used in conjunction with products based on the three main chemical groups to tackle other worms. Combination wormers are also available containing lvermectin and Praziquantel, and Moxidectin and Praziquantel. These products offer great convenience at times when tapeworm treatment is required along with routine worming.

Active chemical ingredients in common brands:

 

Marocyclic Lactones

 

Equest Oral Gel: Moxedectin
Eqvalan Paste for Horses; Ivermectin
Eraquell: Ivermectin
Eraquell Tablets: Ivermectin
Furexell: Ivermection
Noromectin: Ivermectin
Vectin Gel: Ivermectin
Vectin Tablets: Ivermectin

Benzimidazoles

Panacur Equine Paste: Fenbendazole
Panacur Equine Granules: Fenbendazole
Panacur 5 Day Guard: Fenbendazole
Telmin Horse Granules: Mebendazole
Telmin Horse Paste: Mebendazole

Pyrantel Embonates

Pyratape-P Paste: Pyrantel Embonate
Strongid-P Granules: Pyrantel Embonate
Strongid-P Paste: Pyrantel Embonate

Praziquantels

Equitape: Praziquantel

Combinations

Equest Pramox: Moxedectin + Praziquantel
Eqvalan Duo: Ivermectin + Praziquantel
Equimax Paste: Ivermectin + Praziquantel
Equimax Tabs: Ivermectin + Praziquantel

Herbal

 

Multiworm Herbal Liquid
Verm-X Herbal Powder

 

 

Resistance problems

 

Worming is difficult to get right due to the minefield of products available; this is why buying wormers from a trained SQP in a reputable shop is such a good idea as you can get full and complete advice when you buy your wormer.  The medicinal status of wormers may exclude some retailers from selling these products, but seeking out those with qualified staff does help to ensure that the correct wormers are used at the right time of year, thereby minimising resistance development. SQP’s are highly trained and a shop with an SQP on site can really help you ensure your horses are healthy. Alternatively, you can find plenty of advice online, but make sure you provide accurate information on your horses, such as weight and condition.

Despite more information being available, as well as tighter restrictions on sales, wormer resistance is still a growing problem. One way to fight this is to use more faecal egg counts. Testing your horses prior to worming could help reduce unnecessary use of wormers and perhaps limit resistance in the future.

Another way to tackle resistance is to ensure correct dosing. Under-dosing can make worms more resistant so it is vital that you know the body weight of your horses in order to correctly administer the dosage. One problem frequently come across is that horses do not like to be wormed and therefore spit out the product. This affects the dosage and could mean that the horse has not had the correct amount of product. To tackle this problem, wormer manufacturers have come up with the tablet form of wormers, which can be fed like treats to the horse. Palatable, clean and easy to administer, these have changed the way many people worm their horses, however, some horses are fussy and will not readily eat these either! Another way you can ensure correct dosage is by using a special ‘worming bit’. These ingenious contraptions fit on the horse’s head and through the mouth, guiding the syringe to the back of the tongue so that the correct dose is given.

 

Reported resistance

 

Benzimidazoles: widespread resistance in small redworms, reported in many countries around the world.

Pyrantel Embonates: a few reports of small redworm resistance in the UK, but more widespread in the USA where daily low doses are often given in the feed.

Macrocyclic Lactones: A few documented reports of ivermectin resistance in large roundworms, and of ‘reduced efficiency’ of moxidectin against large roundworms in the UK and Holland.

Praziquantel: No reports of resistance.

 

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