Also Known As – Endotoxicosis – Endotoxic shock – Endotoxaemia – Rattle Belly - Slavers
Caused By – Escherichia coli
Introduction
Watery mouth disease is a significant disease and cause of mortality in intensively reared lambs. The disease is often caused by the gram negative cocci ''Escherichia coli'' but can also be caused by other bacterial pathogens.
It is the unique patency and absorption of the neonatal ruminant gut, designed for immunuoglobulin absorption that allows the translocation of the bacteria into the blood from the gastronintestinal tract.
Signalment
Lambs are usually infected during the first 72 hours of life.[1] Newborn lambs are most vulnerable.
Lambs with poor colostrum intake or those born to ewes with poor body condition and mothering skills will be at greatest risk. This also applies to those born in larger litters of three or more lambs.
Clinical Signs
Affected lambs are markedly depressed, inappetant, hand their heads low and produce excessive saliva which often drools from the mouth in long strings. The mouth and face is often cold to the touch. As the disease progresses, lambs become hypothermic, have decreased rumenal motility and distended abdomens. Those that become hypothermic and dehydrated often hasten the onset of coma and death.[1]
When lifted or moved, their gaseous stomach contents often make the strange sound which affords the disease its other common name, “rattle belly”.
Lambs may have normal faeces, diarrhoea or may produce no faeces at all due to atony.
Morbidity in affected flocks can reach 24% of lambs and mortality may be as high as 80%.[2]
Diagnosis
Diagnosis is based on history of the flock and early clinical examination of infected lambs as signs become less specific as disease progresses.
Detection of bacteraemia and endotoxaemia is helpful but also occurs in many other neonatal lamb diseases.
On post-mortem, affected lambs have dehydrated carcasses often with retained meconium. Evidence of excess salivation is often present. The intestine and abomasum are distended with both fluid and gas but enteritis is not usually a feature. Clots of milk are often present in the abomasums and there is usually little or no food within the intestines. Mesenteric lymph nodes are enlarged.
Treatment
Parenteral antibiotics are often indicated, but may increase circulating endotoxins initially due to bacterial cell death. To counteract this, NSAIDs or corticosteroids should be given simultaneously.[1] Success rates are often disappointing in all but the earliest and mildest of cases.
Oral rehydration therapy is essential and can be replaced with intravenous fluid therapy in severe cases where budget is not prohibitive.
Control
Good management practices are vital, i.e. maintaining hygiene in lambing pens and holding pens by regularly disinfecting between batches, ensuring colostrum intake and monitoring ewe health and production. It may be beneficial to consider fostering lambs from large litters of three or more.
Scanning and appropriate management of pregnant ewes to ensure adequate birthweights of lambs will also help to minimise prevalence.
Antibiotics can be used prophylactically on farms where watery mouth is a problem but this should not be undertaken without consideration of resistance issues. Prevention via hygiene and biosecurity is preferred.
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References
Watery Mouth Disease in Lambs, Merck Veterinary Manual, accessed online at http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/22107.htm&word=watery%2cmouth on 21/07/2011.