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Monday, 11 May 2015

Diseases of New Born Lambs

Watery Mouth Disease
·         Colloquial term for the collection of clinical signs shown by lambs affected by this disease. The condition is caused by colonisation of the small intestine by E. coli with rapid multiplication, followed by death and release of toxin.
·         Initial contamination of the lambs’ gut results from a high environmental bacterial challenge from dirty, wet conditions in lambing sheds and pens; along with ewes with faecal staining of the perineum. Colonisation of the gut and rapid bacterial proliferation is facilitated by inadequate or delayed colostrum ingestion, especially in small weak triplets and poorly fed ewes with insufficient colostrum accumulation.
·         Affected lambs are dull, lethargic, depressed and reluctant to suck. They frequently lie in the corner and show little interest to stand or anxiety around humans. Within 2 – 6 hours there is profuse salivation and a wet lower jaw as well increasing abdominal distention even though the lamb has not sucked.  The condition can quickly progress to coma and death.
·         Treatment is more successful in the early stages. Soapy water enemas are commonly used as well as mild laxatives to promote gut activity and expulsion of meconium. Oral antibiotics can be given in the early stages of the disease; spectinomycin is the best drug of choice. Most severe cases often have bacteria in the bloodstream and should be treated with amoxicillin or similar drug intramuscularly. Oral electrolyte therapy should be used 4 times a day (50mls/kg) to help with general well-being.
·         Prevention/Control: as most cases are encountered towards the end of the season, bacterial accumulation is highest at this point. All attempts must be made to avoid contact with this bacteria; this may mean moving the last flock to lamb into a different building, using lime to put on old bedding before new bedding is put down or other techniques such as… using abundant, clean, dry straw; using paraformaldehyde powder on bedding; cleaning and disinfecting individual pens between ewes; collection and disposal or birth material like placenta or large faeces; ensuring short time gap between birth and colostrum intake; use of oral antibiotics within the 15mins of life.

Umbilical Infection (Navel Ill)
Commonly seen 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 antibiotic applied.
·         The infection can remain localised and develop into discrete abscess involving the body wall; however the infection can 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 incorrect navel attention include ascending infection to involve the body, liver and possible more generalised infection to involve the joint, meninges, lungs, kidneys and endocardium. The consequences of infection may not be apparent until some weeks later in the case of chronic severe infections. Prognosis is generally poor so prevention is essential.
·         The navel acts as a gateway entry for bacteria, viruses and infection into the body. These pathogens may cause a range of clinical signs depending on their specific effect or area of infection in the body. Some of the clinical signs and associated afflictions are…

1) Septic Peritonitis: the clinical signs vary with the extent and nature of the peritonitis. Lambs which develop this disease appear very dull and weak within the first 5 days of life. They stand with an arched back and their heads held lowered, lying down most of the time. They may show a subnormal rectal temperature. 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 first signs appearing.

2) Hepatic Necrobacillosis: these lambs also appear dull and depressed, easily caught in the field and look empty/gaunt. These lambs are usually found hiding behind shelter instead of following the dam. Often they are seen with an arched back with all four legs drawn together.

Treatment is largely unsuccessful and should be euthanized for welfare reasons.
Prevention is easily achieved. The umbilicus must be fully immersed in strong iodine within the first 15 minutes of life, in some conditions must be then be repeated 2-4 hours later.

Joint Ill (Infectious polyarthritis)
Localisation of bacteria within joints to cause 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 untreated umbilicus. Bacterial challenge is much greater when lambs are kept in poor sanitary conditions with delayed or insufficient colostrum intake.
·         Clinical presentation: Streptococcus dysgalactiae infections are acquired during the first few days of life with lameness visible from 5 – 10 days old. The number of infected joints is variable. The joints affected, in descending order are, carpal, hock, fetlock and stifle. The affected joints are swollen, hot and painful. Infection causes considerable muscle wastage. After a week the lambs with polyarthritis are smaller than the co-twin and have poor mobilisation.
·         Treatment: is based on procaine penicillin when S dysgalactiae and E rhusiopathiae are the most common joint pathogens. Antibiotic should be administered during the early stages of lameness, daily for at least 5 days. Lameness may persist when bacteria and white blood cells die within the joint and may induce further inflammatory changes.  After two courses of antibiotic and no improvement, the lamb should be culled.

·         Prevention/Control: to prevent this disease all measures should be taken to ensure timely adequate colostrum intake as well as reducing bacterial environmental challenge. The lamb must ingest the minimum amount of colostrum within the first 24 hours. The navel must be fully protected with iodine at 15mins then 2-4 hours later. Single injection of procaine penicillin at 2 days old is sometimes helpful in safeguarding against bacterial challenge.


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