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This article was published in 1962
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INSTITUTE OF INSPECTORS OF STOCK OF N.S.W. YEAR BOOK.
Toxic Jaundice in Pigs
P. S. GREEN, B.V.Sc., Veterinary Inspector, Dubbo
Between May and September, 1961, an unusual mortality in pigs was experienced on at least two holdings in the Dubbo District. The pigs ranged in age from 3 to 5 months and whilst they were in reasonable condition, they were not particularly well grown, On one property a balanced ration of crushed wheat and oats, meatmeal, lucerne meal and antibiotic supplements was fed, whilst the other owner fed only uncrushed oats. Pigs on each holding had access to grazing; on the first property this was mainly lucerne, sub clover and medics, and on the second it was grazing oats. In both cases there was a high proportion of Paterson's Curse, mainly in the rosette stage. The pigs had been observed eating this weed.
CLINICAL SIGNS
Clinical signs were limited. Some animals were found dead, with no prior sickness being observed. It was more usual for the pigs to be obviously sick for up to 5 days before death. Affected pigs were depressed and refused to eat. There was usually marked humping of the back and the gait was often inco-ordinated (sic). The hind legs, in particular, often appeared to be stiff. Icterus of the visible membranes was rarely seen; in the terminal stages there was sometimes a general reddening of the skin of the ears and the underline of the body. No cases of high fever were observed, but several affected pigs had a resting temperature of 104 deg. F. The majority of the sick pigs died, but a few recovered. Recovery was slow and it seems as if they may remain unthrifty.
POST-MORTEM FINDINGS
Post-mortem findings have been variable. At times, icterus, varying from slight to marked, was the only change observed. In some cases there was up to a quart of golden-yellow fluid in the abdominal cavity: similar fluid was seen occasionally in the pericardial sac. Livers varied from slightly yellow to a marked ochre colour. Lungs were sometimes very congested, but pneumonia was rare. Petechial haemorrhages of the atria and the ventricles of the heart and subcapsular and cortical haemorrhages of the kidney were observed in some cases. Slight to severe gastritis was a common finding. The intestines were generally normal, but the mesenteric vessels were noted to be engorged in one case.
A full range of specimens, including pipettes of heart blood, liver, kidney and urine, smears of urine and kidneys, portions of liver and kidneys in formal saline, defibrinated blood, serum samples and turbinates, were forwarded to Glenfield Research Station for examination.
Examination of urine deposits and kidney with both Gram and Fontana staining failed to reveal the presence of Spirochaetes or other organisms. Cultural examination of the kidney, urine, liver and heart, failed to reveal the presence of any significant organisms. Examination of the serum for leptospiral agglutinins eliminated the possibility of leptospirosis as the cause of the mortality. The turbinates showed changes suggestive of Infectious Rhinitis, while the kidney showed general hyaline changes. The liver showed changes which were considered to be consistent with Toxic Jaundice, such as occurs following the ingestion of pyrrolizidine alkaloids and Paterson's Curse (Echium plantagineum) which is known to contain these alkaloids.
Glenfield has advised further as follows:
"Liver changes considered typical of Toxic Jaundice include megalocytosis and lysis of parenchyma, infiltration by small round cels, and proliferation of bile ducts."
In the liver submitted:
"Megalocytosis was recognised but was somewhat masked by lysis of parenchyma and dilation and enlargement of unsupported sinusoids, Leucocytic infiltration included many polymorphs and bile ducts showed virtually no regenerative activity. The peculiarities in this case could suggest a rapidly developed hepatopathy."
In the Young District, similar mortalities have been observed in pigs 4 to 8 months old, in the period June to September since 1954. This period coincides with the growing period of Paterson's Curse. As this weed is widespread in the pig raising districts of New South Wales it is possible that it has been responsible for many obscure mortalities in pigs.