Worming your Horse

There are a number of different species of parasitic worms that infect horses. These include: ascarids (roundworms); large and small strongyles; tapeworms; pinworms; thread worms; stomach bots and lungworms.

Worms irritate the gut lining and lead poor digestion and absorption of feed. Most worms live in the intestinal tract and release eggs that are passed out into the paddock in manure. Eggs will then hatch and larvae develop in the manure and pasture.

Horses grazing grass that has been contaminated with infected manure will ingest the larvae, which then develop into mature adult worms and perpetuate the infection.

How can I tell if my horse has worms?

Horses that have a high worm burden may develop some or all of the following signs:

  • Poor coat condition
  • Poor weight gain or weight loss
  • Diarrhoea
  • Colic
  • Peritonitis

Tests can be run on faecal samples to assess the current worm burden of your horse and identify any resistance to worming products that may be occurring. Regular worming of all horses on your property with an appropriate type and amount of worming product in conjunction with good pasture management, will effectively control worm burdens in your horses.

Products Available from Bega & Cobargo Veterinary Hospitals

The following products are safe to use in all adult horses, mares at all stages of gestation and foals over the age of 6 weeks.

  • Equimax Oral Paste for Horses (Abamectin + Praziquantel)
  • Promectin Plus Allwormer Paste for Horses (Abamectin + Praziquantel)
  • Ammo Allwormer paste for horses (Abamectin + Morantel Tartrate)
  • Prazivec Oral Paste for Horses (Praziquantel + Ivermectin)
  • Equest Plus Tape Long Acting Horse Wormer and Boticide Gel (Praziquantel + Moxidectin)
  • Equiban Granules (Morantel Tartrate)

Basic Steps to good worm control

Below are some points to consider and suggested protocols for worming and pasture management.

  • Worm ALL horses on your property every 6-8 weeks (or as directed by the specific product label). This is especially important in Foals, Mares and yearlings, as these animals are most susceptible to infection. Foals should be first wormed at 6-8weeks of age.
  • DO NOT UNDERDOSE If possible, get an accurate weight on your horses by weighing them on scales or using a weight tape. If you are unable to weigh your horses, estimated weights should be rounded up to the nearest 50 kgs. All worming products have a wide safety margin, so it is safe to dose them a little higher. The use of sub-optimal doses of worming product will only promote the development of worms that are resistant to the worming products available. There are only a finite number of different worming product types. Once resistance is established, we will have no means of treating worm burdens.
  • Regularly alternate the type of worming product used This reduces the risk of resistance to particular products developing. When selecting products to alternate with, try and use ones that contain different drugs. E.g. If you used Ammo Allwormer paste for horses, which contains Abamectin & Morantel Tartrate, 8 weeks later try Equest Plus Tape Long Acting Horse Wormer and Boticide Gel, which contains Praziquantel & Moxidectin. Followed by Equimax Oral Paste for Horses, which contains Abamectin & Praziquantel.
  • Use feed bins This will prevent contamination of feed with infective larvae from the pasture.
  • Pick up manure from paddocks 1-2 times per week This will reduce the number of infective larvae available to contaminate pasture.
  • Spell Paddocks Where possible, rotate the paddocks grazed, allowing them to spell for at least one month – Spelling paddocks will reduce the number of infective larvae in the pasture. This helps break the cycle of re-infection
  • Harrow paddocks after removal of horses Infective larvae dry up and die when exposed to heat and sunlight. Harrowing paddocks breaks up the manure and exposes more of the infective larvae to the heat and sun. This helps to further reduce the number of infective larvae in the pasture and helps break the cycle of re-infection.
  • Rotation grazing with sheep or cattle This is another way of reducing the number of infective larvae in the pasture. Horses and sheep/cattle do not share the same types of parasitic worm species. By grazing cattle or sheep in paddocks, these animals ingest the infective larvae, but these larvae die and are therefore unable to reproduce. These animals therefore act to “clean up” the infective larvae from your pasture.
  • Conduct routine faecal egg counts Faecal egg counts can be performed on faecal samples collected from you horses. Egg counts allow us to assess the current worm burden and give us an indication as to whether the worming products and pasture management used are effectively controlling the worm burden in your horses. Regularly performing faecal egg counts (every 6 months) can allow you to strategically worm your horses, so may allow you to worm them less frequently.

By introducing as many of the above mentioned steps as possible, you will achieve good parasitic control, whilst minimising the development of resistance to worming products.

If you have any further questions about worming your horse, please contact us.