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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.
AVIAN MONOCYTOSIS
B. SINKOVIC, Dr. Med. Vet., Veterinary Research Officer, Veterinary Research Station, Glenfield.
Recent haematological examination of 15 outbreaks of this disease in fowls at the Department of Veterinary Pathology, University of Sydney, confirmed the findings of American workers that relative and absolute monocytosis and moderate leucocytosis are the most significant changes observed. These findings appear to be characteristic and the name of "Avian Monocytosis" instead of the two commonly used names in this State, namely Uraemia or Pullet disease, is considered justified.
There has been a sudden increase in the incidence of this disease over the last 15 months. Records at the Veterinary Research Station, Glenfield, show that from 1943, when Avian Monocytosis was diagnosed for the first time, until 1954 only 19 outbreaks in fowls were recorded as compared with 26 in fowls and 3 in turkeys in 1955; and 12 in fowls and 1 in turkeys in the first three months of 1956. The majority of cases were characterised by urate nephritis, although some outbreaks revealed also necrotic foci in the liver, degeneration in skeletal muscles, misshapen egg follicles, chalky appearance of pancreas, haemorrhages on serous membranes and catarrhal enteritis. Some observations in the New South Wales outbreaks differed from those described overseas, these were:
1. Cases of urate nephritis usually belong to the subacute form of Avian Monocytosis and are characterised by a low incidence and prolonged course. In many outbreaks observed by us there was a high incidence, short course and high mortality; although urate nephritis was the only gross pathological change.
2. Avian Monocytosis apparently affects chickens as young as four weeks while some of our cases were only 7-14 days old.
3. In our experience it is not unusual to find lesions of only one type in any single outbreak; for example, autopsies of affected birds on one property may all show only misshapen egg follicles, while necrotic foci in the liver might be the common lesion in a second outbreak. In America, lesions involving the various organs apparently are seen in each mortality.
4. It has not been possible to associate occurrences of this disease with any change in feeding practice in most outbreaks in this State.
Two recent outbreaks in turkey poults and two in pullets revealed gross pathological changes not described elsewhere. Autopsy of turkeys revealed hydrothorax, ascites, pale liver and some also oedematous swelling of the lower beak. One outbreak in pullets was characterised by hydrothorax, ascites, gelatinous film over the liver surface and haemorrhages on serous membranes, and the second by necrotic foci in liver, urate nephritis, extensive haemorrhages on serous membranes and pale marrow of leg bones. The possibility of haemorrhagic disease being involved in the last outbreak must be considered.
TREATMENT: Molasses in the drinking water and occasionally also change of feed with reduction of protein content is found satisfactory in nearly every outbreak in fowls. Although some beneficial effect of molasses was observed also in turkeys, terramycin and, to a lesser degree, aureomycin in water or and mash with or without change of feed proved fairly effective.