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This article was published in 1956
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INSTITUTE OF INSPECTORS OF STOCK OF N.S.W. YEAR BOOK.
LIVER FLUKE INFESTATION (?)
An Unusual Syndrome
G. CHARLES, B.V.Sc., Inspector of Stock, Forbes.
The owner of a property situated at Ootha, approximately 50 miles northwest from Forbes, requested an investigation on 1st February, '56, as he had lost about 50 sheep over the preceding 14 days. The dead sheep were portion of a mob of 2,500 Merino ewes of mixed ages, running in a paddock subject to inundation by the Goobang Creek, which rises in the hills 60 to 70 miles to the east. The grazing was natural pastures consisting of Chloris spp. Danthonia spp., Eragrostis spp., Bassia quinquecuspis, Swamp grass, Ball clover (mostly dried off), "Nardoo" (Marsilea Drummondii) and some reeds. The timber was predominantly Eucalyt.
Affected sheep presented two different pictures and were designated arbitrarily as acute and chronic cases. The former were rarely seen to be sick and usually were found dead in the paddock. The chronic cases were readily distinguished as they exhibited laboured respiration and a marked oedema of the throat; often extending upwards and involving the face. Closer examination revealed injected conjunctivae, while other visible mucous membranes were slightly cyanotic. The oedema extended down the neck to the sternum.
Post-mortem examination of a so-called acute case, dead about 2 hours, revealed a carcase in good condition with no outwardly visible signs of oedema, and with engorged subcutaneous blood vessels. The abdominal cavity contained about 300 ml. of cloudy fluid containing some fibrinous clots. The omental fat was petechiated. The omasum was hard and the contents very dry, while the abomasum exhibited a catarrhal abomasitis. The full length of the intestinal tract showed minor inflammatory changes. The liver was enlarged and cirrhotic, with small yellow necrotic areas up to 5 mm. in diameter scattered throughout. The kidneys appeared normal. The diaphragm showed subserous oedema, especially on the pillars. The thoracic cavity contained about 500 ml. of clear fluid in which were flecks of fibrin, and the whole coagulated rapidly on exposure to air. The lungs were congested and fibrous. The pericardial sac contained 100 ml. of clear fluid and the heart appeared normal.
A &quto;chronic" case died while being examined, and the post-mortem examination revealed a generalised oedema. The abdominal cavity contained about 1500 ml. of cloudy fluid. The gastro-intestinal tract appeared normal apart from some oedema of the submucosal layer. The kidneys were slightly enlarged and on section the medulla was dark red and the pyramids were oedematous. The liver was enlarged, cirrhotic and friable and there appeared to be some interlobular distension. Numerous yellow necrotic areas were evident. There was no evidence of liver fluke. The thoracic cavity contained between 3 and 4 litres of clear fluid with clots of fibrin. The lungs were oedematous. The pericardial sac contained about 200 ml. of clear fluid. The heart was pale, flabby and enlarged and exhibited petechiae and ecchymoses on both surfaces.
The liver condition was common to both types of cases and was considered to be due to parasitic invasion, but no parasites could be discovered. Specimens were taken and submitted for examination. The owner was advised to remove the sheep from the paddock and to drench them with carbon tetrachloride, using large doses to remove possible immature fluke. However, this was not done and 5 weeks later losses had reached 330.
On 14th March, 1956, a further examination of a so-called "chronic" case was made, revealing the same picture, but with the important difference that about 30 liver fluke were found. The owner, now being convinced by the sight of the fluke, moved the sheep to another property in the Condobolin district and drenched them. Losses continued for a period and then ceased.
The Director of Veterinary Research suggested that the condition showed a distinct resemblance to the so-called "Jelly Disease" which had been fairly common in 1941, but which had been almost unheard of since that time. Various therapeutic measures were suggested but not adopted by the owner, even on a trial basis. The D.V.R. also stated that the general pathology of the condition was suggestive of Clostridial infection and that the presence of the extensive oedema indicated a possible Clostridium novyi (oedematiens) infection. However, cultures from pipettes of tissue taken from the periphery of the necrotic areas of the liver failed to reveal the presence of the organism; as also did guinea pig inoculation.
Fluke snails no doubt were carried on to the land by floodwaters over the past few years and although no known fluke infested sheep had been on the property and certainly no fluke had been seen in the ration sheep killed, cattle had been agisted on the property, and these could have been infested. Alternatively the possibility of infected snails being carried down by the floodwaters cannot be overlooked. There would appear to be no further explanation for the presence of fluke in an area where they do not normally exist.
The presence of Nardoo—Marsilea Drummondii—in the pastures is a further complication and may explain some of the deaths labelled "accute", insofar as these deaths were precipitated before the oedema developed. The presence of diffuse gastro-intestinal inflammation tends to support this.
Despite the failure to determine the cause of the oedematous condition, it is felt that a clostridial infection is the most likely explanation. This syndrome of oedema associated with liver fluke infestation has not been encountered previously and is consequently recorded as being of some interest.