ARCHIVE FILE
This article was published in 1974
See the original document
Haemorrhagic Enteritis in Lambs
by M. R. Barry, B.V.Sc.
A problem came to notice on 20th April, 1966 in Lambs on a property at Holbrook. Three Lambs out of a flock of 118 had died. A ram lamb examined fourteen hours after death revealed congested muscle with gas and blood tinged gelatinous fluid in the subcutaneous tissue over the rump, flank, shoulder and neck. Petechiae were present on the heart wall and thymus and blood tinged pericardial fluid was present. These lambs had been grazing on a Lucerne pasture. The lambs had been vaccinated for entero-toxaemia in September, 1965 and again about 6th April, and put on green lucerne 3 days later.
Laboratory examination of smears from this ram lamb showed that a light clostridial flora was present and on fluorescent anti-body technique showed the bacterial flora to be predominately Cl. chauvoei with Cl. septicum and Cl. novyi also present in small numbers.
On 15/6/1966 a lamb observed by the owner to be standing on its own and then lying down for about one hour before death. Autopsy revealed intense haemorrhagic enteritis commencing distal to the abomasum and terminating at the rectum, Haemorrhages were present over most of the interior of the left ventricle but did not appear on the rest of the heart. The intestines were ballooned with gas.
There were 2,200 mixed sex lambs, 9 to 10 months old in the flock and approximately 50 had died.The lambs were put onto lucerne on 10/6/1966 and the first lamb died at 4.00 pm., 14/6/1966. The owner had observed that losses like this occur only on lucerne and only after the lambs have had a few days grazing the lucerne.
Laboratory examination of pipettes from the lamb autopsied on 15/6/1966 revealed non haemolytic coliforms in the colon and non haemolytic coli forms and Clostridium welchii in the smaller intestine.
Histopathology of the heart muscle revealed a mild localised subacute interstitial myocarditis.
Investigation at that stage appeared to indicate that the problem could be a septicaemia or entero-toxaemia, possibly due to coliform or clostridial bacteria. It appeared that grazing lucerne was a conditioning factor in the cause of the mortality but to alter management by grazing alternate pasture posed a problem as the lucerne had been sown particularly to graze Lambs on it during the dry autumn period in order to maintain maximum growth rate at a time when annual species provide poor grazing on the property.
On 4/2/1970, more lambs were dying in a similar way in a flock of 1,000 Merino lambs 5 to 6 months old and well grown. Some 30 lambs had died over 4 weeks. They were usually found dead and only an odd one was seen sick. Those which were sick showed distress and went down with rapid respiration rate, stopped breathing and died within an hour.
As in earlier years they had been grazing continuously on pure lucerne for the last six weeks. The Lucerne was in the stage of coming into flower to stalky. Losses started 3 to 4 days after change to a fresh paddock. The flock usually spent 8 to 10 days on a paddock before being moved to another lucerne paddock. All the effected sheep were bred on the property and only lambs were effected but the older sheep did not have access to the grazing lucerne.
A lamb seen to be sick at 11.30 a.m. on 3/2/1970 was closely observed by the owner and the intestines were removed 3 minutes after death and placed in a refrigerator. This material was presented to me the following morning. It was well preserved but showed intense congestion and haemorrhage along the small intestine and colon and also part of the caecum. The mesenteric vessels were congested. Blood oozed from the bowel wall and fibrin clots formed in stagnant fluid on a stainless steel sink.
Culture of contents from the colon and small intestines (4 sites) revealed a heavy growth of non-haemolytic coliforms and alpha, haemolytic streptococci. Multiple smears of small intestine, colon and caceum revealed no significant organisms.
Histopathology of mesenteric lymph node revealed diffuse oedema and congestion with areas of haemorrhage in lymphoid follicles. Histopathology of the small and large intestine revealed intense mucosal congestion and haemorrhage but as the enteric epithelium was largely still intact, little haemorrhage had occurred into the lumen.
On 1/5/1970, a further Lamb was examined. The flock was still grazing on lucerne and 15 had died in the previous 10 days. Laboratory examination of pipettes of intestinal contents revealed a moderate growth of non haemolytic coliforms in one pipette and a heavy growth of non haemolytic coliforms, a few haemolytic coliforms and a haemolytic streptococci in the second pipette.
In April, 1971 the possibility of fungal infection on Lucerne was considered as the common leaf spot fungus, Pseudopeziza medicaginis on lucerne had been found by overseas workers to increase the coumestrol content of lucerne. As there were haemorrhagic lesions in the Lambs which died it was decided to submit samples of lucerne for examination for this or other fungus species.
Accordingly on 24/4/1971, 3 plastic bags of lucerne plucked at the stage when the first death had occurred in that paddock were forwarded to the laboratory at Glenfield for examination. The animals at that stage were well grown Merinos, 6 to 7 months of age.
Two deaths occurred in the weeks ending 10th April, 1971, 7 deaths in the week ending 17th April, 1971 and 2 deaths in the week ending 24th April, 1971. The owner had observed that there had been a tendency for bloating just prior to death. The samples of lucerne were negative to the DPB test for nitrate and produced no ill effects when fed to guinea pigs over a period of 5 days.
No physical abnormality was evident on microscopic examination of the plant material.
On 13/3/1974, the Holbrook property was visited and it was found that no deaths had occurred in lambs which had been grazing lucerne continuously since early December, 1973.
It is interesting that in the autumn of 1973 when surplus lucerne was available for grazing the owner attempted to induce deaths in older sheep by grazing them on lucerne similar to that on which lambs were dying. No deaths occurred however in the older sheep.
The problem of lambs dying from haemorrhagic enteritis on lucerne in the Holbrook area was reported by Barry (1971) and it was subsequently learnt that similar deaths had occurred in South Australia, where deaths occur when the lucerne is young and vigorous. Deaths occur sporadically from July to December in sheep usually under the age of 18 months and post-mortem examination reveals haemorrhagic enteritis. Hodge, 1972). It was later reported to be occurring in several areas of South Australia. (Collard, 1973).
Investigation of such a problem is made difficult by the intermittent nature of the losses, the relatively low incidence of the problem and the usual finding of a dead animal, partly decomposed.
It has been reported by Gumbrell and Jagusch (1973) that sporadic deaths in young sheep grazing lucerne in New Zealand present a "red gut" syndrome. Trials have been conducted at Lincoln College since 1969 and losses of 1 to 2% have been recorded in the experimental flocks.
In a trial conducted at Lincoln College from September 22, 1972 to January 12, 1973, 49 lambs died suddenly in an experimental flock of 575 animals growing at the rate of 0.3kg. per day. of 24 lambs examined post-mortem during this period, all showed lesions of "red gut", including intestinal torsions described by Gumbrell (1972).
Slaughter of clinically ill lambs confirmed the association of torsion of the intestinal mass with "red gut".
It will be of interest to examine any future lambs which die after grazing on lucerne paddock at Holbrook to see whether similar torsion of the intestinal mass is present. It was not specifically looked for in the past and may well have been present.
Acknowledgements.
My thanks are expressed to the Chief, Division of Animal Industry, for permission to use Departmental records and to Mr. D. Vickery of "Fairview", Holbrook for his interest and cooperation.
References
Barry, M.R. (1971) Aust. Vet. J., 47:220
Collard, J.A, (1973) Personal communication
Gumbrell, R.C. (1972) Paper presented to N.Z. Soc. Vet. Comp. Path. Abstract in N.Z. vet, J., 20:197 (1972)
Gumbrell, R.C. & Jagusch, K.T. (1973) - N.Z. vet. J., 21:178
Hodge, R.J.R. (1972) Personal communication.