HORSE WORMS
Horses are commonly infected with gastrointestinal nematodes, trematodes and cestodes.
1. Gastronintestinal Nematodes (Round Worms)
The most important worms found in horses are:
- Large strongyles (Strongylus spp.)
- Small strongyles (Cyathostomes)
- Large roundworms (Ascarids)
Other common worms are listed in Table 3.1 and include:
- Intestinal threadworm (Strongyloides westeri)
- Stomach worms (Trichostrongylus axei)
- Pinworm (Oxyuris equi)
2. Trematodes (Flukes)
- Liver fluke (Fasciola hepatica) is an important parasite of horses in certain areas where conditions are suitable for the intermediate host, an aquatic snail.
- Stomach fluke (such as Paramphistomum spp or Calicopheron spp) occasionally cause disease, mainly in coastal areas.
3. Cestodes (Flatworms)
- Tapeworm (Anoplocephala perfoliata)
4. Bots (Gastrophilus spp.)
- Bots are the larvae of a fly not worms. They will not be detected during a WEC.
5. Coccidia (Eimeria)
- Coccidia are microscopic protozoal parasites not worms..
COMMON HORSE WORMS (Table 3.1)
| Common Name | Scientific Name |
|---|---|
| Most Important Roundworms | |
| Large strongyles | Strongylus spp. |
| Small strongyles | Cyathostominae |
| Large roundworms | Parascaris equorum |
| Intestinal threadworm | Strongyloides westeri |
| Stomach worms | Trichostrongylus axei |
| Pinworms | Oxyuris equi |
| Cestoda (tapeworm) | |
| Tapeworm | Acocephalia perfoliata |
| Trematodes (flukes) | |
| Liver fluke | Fasciola hepatica |
Source: Beveridge, I., Gasser, R., Sangster, N. (2015). Horses. In: Beveridge, Ian, and Emery, David, (eds.) Australasian Animal Parasites: Inside & Out. Australian Society for Parasitology, pp. 792-841
GUIDE TO WORM EGG COUNTS IN HORSES – Table 3.2
| Worm egg count (epg) | Interpretation / comments |
|---|---|
| 0 - 100* | A good result. There would be few situations where you would contemplate drenching at this level. Check egg counts in 4-6 weeks after significant rain. |
| 100 - 200* | Low egg count result. Treatment may be required in younger animals or animals under stress. If not treated check egg counts in 4 weeks time. |
| 200 - 500* | Moderate egg count result. Treatment would be advisable in most cases. |
| Above 500* | High egg count result. Treatment required. |
*strongyle eggs per gram of faeces (epg)
Source: Anne Oakenful, (2008). Revised by Stephen Love, September 2013. NSW DPI Faecal Egg Counts for Worms Manual.