There are two types of copper poisoning:
1. Acute poisoning: aThis occur when sheep are given copper for the prevention of copper deficiency.
2. Chronic poisoning: Occurs when copper accumulates in the liver due to intake of copper from the diet. Chronic copper poisoning is far more common.
There is no specific antidote to copper poisoning, and the condition causes much distress and is usually lethal once clinical signs are present. The diet has to be changed immediately to prevent further cases.
Possible Causes
Things that can trigger copper poisoning are not fully understood. It is thought that stressful activities like transportation, bad weather, rough handling, deprivation of food for a short period may precipitate cause it. Feeding too much of high-copper feedstuff like brewers’ grains, palm kernel cake, goat/cow/pig concentrate feed is bad. Concentrates and hay contains more available copper than fresh forage or root crops. Some sheep breeds are more susceptible to copper poisoning than others. Try to avoid using copper in areas where sheep are, including in footbaths, spray against snails (can transmit liver fluke), copper pesticides
Symptoms of Copper Poisonong
Wandering aimlessly, head pressing and generalized weakness. As jaundice and anemia set in, breathing becomes shallower. Urine is often dark in color due to hemolysis . Death is rapid. Diagnosis is based on housing and feeding history in combination with clinical signs and post mortem findings of a pale liver and black kidneys. Liver copper concentration will confirm diagnosis. (Sargison, 2016 ).
Control and Prevention
Copper poisoning is unlikely when sheep are fed mainly grass and less concentrate. Feedstuff low in copper must be used in housed flocks (<10ppm), especially where sheep susceptible to copper poisoning are kept. Cheap feeds high in copper, such as distillery by-products, should not be fed to purebred and crossbred sheep susceptible to copper poisoning. Food compounded for other species (Gough, 1991 ) or which contains the by-products of other species (e.g. poultry litter) must not be fed to sheep. Copper sulphate for snail control should be avoided.
Under circumstances where supplementation is needed to prevent copper deficiency, this should involve veterinary consultation. An accurate diagnosis should be obtained before any treatment or preventive measures are implemented. Only one source of copper should be made available and every effort should be made to avoid causing stress to animals during copper treatment and for a period afterwards. Anthelmintics and any period of food deprivation around the time of copper treatment should be avoided (Henderson, 1990 ).
There is evidence that the incidence of copper toxicosis in sheep may be controlled by increasing their dietary zinc intake (Bremner et al., 1976 ).
Treatment
Effective control of copper poisoning in sheep was obtained by subcutaneous injection of three doses of ammonium tetrathiomolybdate at 3.4 mg/kg bodyweight on alternate days. This caused a substantial reduction in liver copper content and in liver damage and reduced mortality rate in animals that had developed the hemolytic crisis. No adverse side-effects of the treatment were observed (Humphries et al., 1988 ). Intravenous injection is also effective ( Humphries et al., 1986 ) but less convenient. A combination therapy of tetrathiomolybdate and d-penicillamine (degradation product of penicillin that chelates copper) has also been identified as being useful to maximize copper removal from the body (Gooneratne and Christiansen, 1997 ).
Fresh seaweed offered to sheep with symptoms of copper toxicity appeared to be therapeutic, leading to a reduction in blood plasma copper level ( Wiener et al. , 1977 ).
Copper antagonists such as molybdenum or sulfur can be added to the diet to prevent further liver accumulation (Sargison, 2016 ).
Good Practice Based on Current Knowledge
•Do not feed excessive levels of concentrate to sheep.
•Do not feed concentrates high in copper levels to sheep, especially to sheep breeds susceptible to copper poisoning and housed sheep.
•Do not feed sheep food compounded for other species.
•Do not use copper sulfate for the control of snails in areas where sheep are grazing.
•When supplementing sheep with copper, make sure only one source of copper is available and avoid stress during copper treatment and for a period afterwards. Avoid anthelmintics and any period of food deprivation around the time of copper treatment.
•If cases of copper poisoning occur, immediately notify the named veterinary surgeon.
Kudos to:
https://www.farmhealthonline.com/US/dise...-of-sheep/