Glossary
(some terms explained)
Egg count - various methods which can help to show the level of worm burden carried by a goat or sheep whereby the appearance of parasitic worm eggs in the faeces of the animal is indicative of the presence of adult worms shedding eggs as part of their life cycle.
EPG - eggs per gram. This is how the results of each count is presented and basically shows the number of eggs found in each gram of faeces at the time of the test.
Egg count reduction test - also known as the faecal egg count reduction test. An important test in the assessment of resistance to worming chemicals. The test consists of an egg count performed before worming and at a certain number of days following administration of the chemical, depending on which wormer is being used. It is done on animals with counts of at least 300epg and the degree by which the number is reduced is indicative of the degree of resistance to the chemical being used. This test is essential if you have been worming regularly and suddenly get inexplicably high worm egg counts, or if you are concerned about your strategy.
Host - in this instance, an organism which carries and supports one or more of the developmental stages of the parasites.
Life cycle - the stages an organism passes through from egg to sexually mature adult.
Parasite - an organism which needs another organism (host) to complete its life cycle, acquire food etc, but which does so to the detriment of the host.
Resistance - a term often interchangeable with 'tolerance', in this case denoting the ability of an organism to survive levels of chemicals which would normally bring about its death or removal from the host.
Subclinical disease - where disease is present yet signs of it are not obvious by visual assessment and the animal appears normal.
Selection pressure - where a force (eg chemical) acts on a population of individuals such that some individuals which are not adversely affected by the force can continue their life cycles and produce more offpring with the ability to thrive in the adverse conditions. This leads to a gradual alteration in the population so that numbers of 'resistant' individuals increases and the force has less effect on the general population.
Worms - nothing to do with the harmless wiggley things found in the compost heap but another name for 'nematodes' which include a number of parasites important to goats and sheeps and discussed here.