Watery mouth disease is a colloquial term used to describe a collection of clinical signs in neonatal lambs which includes lethargy, unwillingness to search for the teat and suck, profuse salivation, increasing abdominal distension and retained meconium.
The condition is caused by colonisation of the small intestine by E. coli with rapid multiplication and release of toxin.
Initial contamination of the lambs' gut results from a high environmental bacterial challenge from dirty wet conditions in the lambing shed and pens, and ewes with faecal staining of the wool of the tail and surrounding the perineum. Colonisation of the gut and rapid bacterial proliferation is facilitated by inadequate and/or delayed colostrum ingestion especially in small weakly triplets, and poorly fed ewes in low body condition with insufficient colostrum accumulation.
Watery mouth disease is commonly encountered in twins but especially triplet lambs aged 12 to 36 hours kept in unhygienic conditions. Affected lambs are dull, lethargic, depressed and reluctant to suck. They frequently lie in the corner of the pen and show little interest in sucking when encouraged to stand. They rarely stretch themselves when they stand. Within 2 to 6 hours there is profuse salivation, a wet lower jaw and increasing abdominal distension although the lamb has not been sucking. The condition can quickly progress to coma and death.
Despite abomasal distension in lambs with watery mouth disease, oral electrolyte therapy at a rate of 50mls/kg four times daily is essential to prevent dehydration. During the early stages soapy water enemas, such as diluted washing-up liquid, are commonly used. Mild laxatives/purgatives also promote gut activity and expulsion of meconium. Oral antibiotics may be effective during the early phase of the disease; however, veterinary advice should always be sought to ensure appropriate treatment is administered.
Problems with watery mouth disease are almost invariably encountered in housed flocks towards the end of the lambing period caused by a build up of infection. All attempts must be made to improve hygiene standards in the lambing shed. Wherever possible, the remaining pregnant ewes should be moved to another building, or weather permitting, turned out to pasture. It is important to ensure lambs receive enough good quality colostrum to ensure adequate passive antibody transfer.
Antibiotic administration to prevent watery mouth disease in lambs must be carefully considered and is not routinely recommend. This is due to the potential risks of selecting for resistant bacteria which may transfer to humans. Discuss all use of antibiotics with your vet.
Navel ill is common in young lambs born into unsanitary conditions where there is inadequate navel treatment. It is more common during inclement weather and in male lambs presumably because urination delays desiccation of the umbilicus and removes some of the topical astringent/antibiotic applied by the shepherd.
Umbilical infections may remain localised and develop into a discrete abscess involving the body wall or extend to peritonitis, and liver abscessation. Umbilical infection with Fusobacterium necrophorum with subsequent spread to the liver causes the specific condition of hepatic necrobacillosis.
The consequences of nil/incorrect navel dressing include ascending infection to involve the body cavity, liver, and possibly more generalised infection to involve the joint, meninges (brain), lungs, kidneys, and endocardium (heart valves). Navel infection can be readily prevented; prognosis is largely hopeless. While infections gain entry through the undipped navel within the first few hours of life the dreadful consequences for the lamb may not be fully appreciated until some weeks later after a considerable period of suffering (hepatic necrobacillosis).
The clinical signs vary with the extent and nature of the peritonitis. Lambs which develop septic peritonitis within the first five days of life appear very dull and weak. They stand with their back arched and heads lowered and spend long periods lying in the corner of the pen. The rectal temperature may be subnormal. These lambs do not suck but increasing exudation in the peritoneal cavity, causing moderate distension, contrasts with the lamb's gaunt appearance and expression. Affected lambs rapidly become dehydrated and die within a few days of clinical signs first appearing.
Typically, affected lambs are first noted from 10 to 14 day-old when they appear dull and depressed, and in much poorer condition than their co-twin. They have an empty gaunt appearance and are too easily caught in the field. Affected lambs may not follow the ewe and co-twin and are found sheltering behind walls and hedgerows etc. Affected lambs stand with an arched back and all four legs drawn together.
Treatment of septic peritonitis and hepatic necrobacillosis is hopeless and lambs should be euthanased for welfare reasons.
The umbilicus (navel) must be fully immersed in strong veterinary iodine BP within the first 15 minutes of life and repeated at least 2 to 4 hours later. Antibiotic aerosol sprays are much inferior to strong veterinary iodine BP for dressing navels, and are much more expensive. All umbilical infections are a direct consequence of neglecting sound husbandry practice.
This essential routine procedure must be undertaken when the ewe and her lambs are penned soon after birth, and again 2 to 4 hours later when the shepherd checks that the lambs have sucked colostrum as outlined earlier. Note that all these procedures can be fitted into a routine such that none is overlooked.
Localisation of bacteria within joint(s) to cause an infectious arthritis with moderate to severe lameness is a major economic problem and welfare concern. Bacterial spread through the bloodstream in neonatal lambs results from entry via the gut, upper respiratory tract, tonsil, and perhaps the untreated umbilicus. Bacterial challenge is much greater when lambs are kept in poor sanitary conditions with delayed or inadequate colostrum intake.
Streptococcus dysgalactiae infections are acquired during the first few days of life with lameness visible from five to 10 day-old. The number of infected joints is variable; only one joint is affected in approximately 50 per cent of lambs with 2 to 4 joints in the remainder. The joints most commonly affected, with decreasing frequency, are the carpal joints, hock, fetlock, and stifle joints. The affected joint(s) are swollen, hot, and painful. Infection causes considerable muscle wastage. After only one week lambs with polyarthritis are smaller than their co-twin and in poorer body condition.
Lameness affecting a single leg may result from a foot abscess or interdigital lesion. Dog, fox, and possibly badger, bites are very uncommon. Trauma to joints may cause marked lameness; the stifle is the most commonly injured joint.
Diagnosis of an infected joint is based upon clinical findings although it may prove difficult to differentiate traumatic lesions from early infective conditions. In lambs less than one month-old all lameness and swollen joints should be considered septic until proven otherwise.
Procaine penicillin is the drug of choice for polyarthritis where S dysgalactiae and E rhusiopathiae are the most common joint pathogens accounting for over 90 per cent of positive joint fluid cultures. Penicillin administered once daily for at least five consecutive days during the early stages of lameness effects a good cure rate in many S dysgalactiae infections although dead bacteria and white blood cells within the joint may induce further inflammatory changes such that some degree of lameness persists.
Lambs with polyarthritis that continue to show moderate to severe lameness after two courses of antibiotic therapy do not grow well and represent a major welfare concern. These lambs must be euthanased for welfare reasons.
Every effort must be taken to reduce the risk of bacteraemia by ensuring timely adequate passive antibody transfer and reducing environmental bacterial challenge. The lamb must ingest sufficient colostrum (200 mls/kg) during the first 24 hours of life and 50 mls/kg within the first 2 hours, if not earlier. The umbilicus (navel) must be fully immersed in strong veterinary iodine BP within the first 15 minutes of life and repeated at least once 2 to 4 hours later. Change of lambing accommodation is rarely an option; turnout to pasture for the remainder of the lambing period has been reported to markedly reduce morbidity.
There are no specific recommendations for the control of S dysgalactiae polyarthritis. A single injection of procaine penicillin to all lambs at 36 to 48 hours-old is very effective in the face of a disease outbreak but must be considered as a last resort after all aspects of lamb management and husbandry practices have been reviewed. The use of prophylactic antibiotic injections to control diseases that can be controlled by good husbandry practices are coming under ever closer scrutiny by regulatory bodies.
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