Grazing animals in Australia are rarely free of worm infection, though effects on stock health and productivity vary widely. Clinical effects of enteric parasitism include ill thrift, diarrhoea, anaemia, and death in severe cases. The degree of damage is influenced by the numbers and identities of the parasites present, host age, immunity, general health, and nutrition.
Faecal egg counts (FECs) are used to monitor the effectiveness of worm control programmes, help in the differential diagnosis of cases of scouring and ill thrift, aid drench decision-making, and investigate suspected drench resistance.
Any statement regarding significance of FECs will only be a guide. Interpretation must take into account the age, class, origin, state of nutrition, environment, stage of season, and concurrent disease state of infected animals.
Horses
FECs are only an approximate guide to worm burden. Clinical history and knowledge of seasonal pattern of parasites in specific geographical regions will assist in interpretation of FECs. The following FECs may indicate clinical disease:
Up to 15 months of age – 100 epg
2-year-old – 200 epg
2-6-year-old – 400 epg
>6-year-old – 600 epg
FECs provide little information on the identity of the worm genera represented. This can be overcome by the use of faecal larval cultures in conjunction with FEC. FEC and larval culture are both necessary for the calculation of faecal egg count reductions to determine drench resistance.
Species:
Cattle, sheep, horses, camelids, deer, dogs, cats, birds
Specimen:
2-4 g faeces per animal
Container:
Plastic pot (the use of egg cartons is not recommended due to drying out and cross-contamination of samples during transport)
Collection protocol:
Collect samples directly from rectum of animal (not from the ground unless freshly passed onto clean yard)
Special handling/shipping requirements:
Submit fresh or store in a refrigerator* until transport to a laboratory. Do not freeze.
*It is important that faecal samples for larval cultures are not refrigerated at all. In cases where both FECs and larval cultures are required on the same set of samples it is recommended that a sub-sample be removed from each individual sample and pooled. The individual samples for FEC can be refrigerated while the pooled sample should be clearly identified as being for larval culture and kept at room temperature.
References:
McKenna PB. The diagnostic value and interpretation of faecal egg counts in sheep. New Zealand Veterinary Journal 29:139-32, 1981
Medina-Torres C. Ascarid infestation. In: Blackwells Five-minute Veterinary Consult: Equine, 2nd edition. Lavaoie JP, Hinchcliffe KW (eds). Wiley-Blackwell, Ames, pp96-7, 2008
Parkinson TJ, Vermunt JJ, Malmo J, Anderson N. Disease causing diarrhoea. In: Diseases of Cattle in Australasia: A Comprehensive Textbook. Parkinson TJ, Vermunt JJ, Malmo J (Eds). Vetlearn, Wellington, pp155-72, 2010