Parasite control - Donkey

Parasite Control

The anthelmintic control programme operating at The Donkey Sanctuary is reviewed regularly to ensure that:

• it is effective in controlling pasture contamination
• it reduces the incidence of cyathostomosis
• it slows down the development of resistance to anthelmintics
• it is cost-effective. The reduced cost of anthelmintics has offset the increased laboratory costs.

Cyathostomin control

At The Donkey Sanctuary no donkey is given an anthelmintic unless it is deemed necessary by a clinician taking into account the animal’s history and recent FECs. Clinical cases presenting with cyathostomosis are treated with anthelmintics regardless of faecal egg count results.

This programme means regularly examining the faeces of all the donkeys, as opposed to administering treatment to the whole herd. Benefits include:

1. To reduce handling and stress to the donkey when the whole herd is dewormed
2. To reduce exposure of adult worms to repeated doses of anthelmintic and therefore development of drug resistance
3. To help create a ‘refugia’ of susceptible larvae on the pasture to compete with resistant strains
4. To avoid unnecessary environmental pollution with anthelmintics
5. To preserve drugs for the future

Other parasites

Any positive count for tapeworm, lungworm, liver fluke, ascarid or pinworm warrants anthelmintic treatment (see endoparasiticides for recommended drugs).

Pasture hygiene

It is claimed that 99% of worms occur on the pasture, whereas 1% occur in the horse (Rose et al, 2000). This statement is equally applicable to the donkey and so no worm control programme should depend solely on drugs. It should also include good pasture and stable management:

• Good stable and pasture hygiene
• Rotational grazing, proper pasture management and harrowing pastures (when weather conditions are optimal) is most important
• The use of a ‘biological vacuum’ (sheep³ ) is still pertinent to ingest larvae on the pasture and is used on the Donkey Sanctuary’s land both in winter and early spring.
• Removal of dung at least twice a week either manually or mechanically significantly reduces pasture contamination (Corbett et al)
• Faecal sampling should be conducted at least four times a year
• If donkeys are at pasture in the winter months then faecal sampling may need to be carried out throughout the year depending upon weather conditions
• Grazing pasture should be rested for as much of the year as possible
• Managing young stock, which has lower natural immunity to parasites, on separate pastures from older groups

³ The use of sheep may increase the incidence of the stomach worm Trichostrongylus axei, but the pathogenecity of this species in donkeys is rarely a problem.

The above principles can be applied to donkeys in most cases. Owners should always be advised to consult their veterinary surgeon regarding periodicity of faecal sampling/worming with regard to their own specific circumstances.

Working donkeys

Under tropical weather conditions in most developing countries, the dry season is not favourable for the development and survival of the free living and parasitic stages and so there is relatively little danger of acquiring infection at this time of year. Generally, animals have a high probability of acquiring infection from pasture during and immediately following wet seasons. Treating donkeys at the beginning and end of the rainy season therefore seems to be sufficient under such climatic conditions. This is usually practised in Ethiopia and other developing countries where the farmers cannot afford frequent testing and/or treatment for their animals.

The efficacy of worming strategies in any country should be carefully monitored by laboratory analysis and condition scoring. An epidemiological assessment of weight loss or anaemia should complement any monitoring process to determine the impact of dental disease and/or poor nutrition.

References

• Christopher J Corbett, Sandy Love, Anna Moore, Faith A. Burden, Jacqui. B. Matthews, Matthew Denwood. January 2014. The effectiveness of faecal removal methods of pasture management to control the cyathostomin burden of donkeys. Parasites and Vectors. 7:48.
• Rose, R.J., Hodgson, D.R. (2000). Manual of Equine Practice. W.B Saunders, Pennsylvania, USA.