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This article was published in 1964
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INSTITUTE OF INSPECTORS OF STOCK OF N.S.W. YEAR BOOK.
Some Observations on Neoplasia in Meat Animals in North Western N.S.W.
PETER T. DIPLOCK, B.V.Sc., Veterinary Inspector, Warialda.
As there appears to be little reference in Australian veterinary literature to neoplastic conditions observed at slaughter in cattle and sheep, a limited survey was conducted to determine the approximate incidence of various types of neoplasia in these species, and also to correlate the Meat Inspector's macroscopic assessment with histopathological findings.
Investigations were carried out at North West Abattoirs, a privately owned killing works located at Inverell, N.S.W., where, during the three month period of this survey from 27/6/63 to 21/9/63, a total of 74,760 sheep and lambs and 4,324 cattle were inspected by State Meat Inspectors, the total number of sheep including 21,161 lambs.
PROCEDURE.
When a suspected neoplastic condition was detected macroscopically by the Meat Inspector, a record was made of the origin, breed (cattle only), sex, age (if possible), weight of carcase, location and macroscopic appearance of the tumour, and a sample collected where possible for subsequent histopathological examination.
Samples were numbered serially and the histopathological findings subsequently checked against the tentative diagnosis made macroscopically.
Accurate determination of age was impossible in most cases as the system in use at this abattoirs leads to the head being removed from the carcase before it is received by the Meat Inspectors.
A. ORIGIN OF ANIMALS.
The supply of cattle and sheep to North West Abattoirs, Inverell, during the three months of this survey was largely drawn from the Pastures Protection Districts of Moree, Warialda and Inverell with smaller numbers from the Narrabri, Tamworth, Tenterfield and Armidale districts.
B. SPECIES INCIDENCE.
During the three months of the survey 20 samples were obtained from cattle and 42 from sheep, excluding lambs, representing an incidence of 0.46% and 0.078% respectively.
There were no condemnations among the lamb portion for neoplasia during the period.
C. TYPES OF NEOPLASM IDENTIFIED
Of the total of 62 samples collected, 11 were not submitted for histopathology, for various reasons, but the remaining 51 specimens showed the following incidence in the two species:
1. SHEEP.
| Type of Tumour | Location of Tumour | No. of Cases | % Age of Total Examined Histologically |
|---|---|---|---|
| Fibroma (?) | Liver and spleen, duodenal wall, adrenal gland, thoracic cavity, tibia | 6 | 16.1% |
| Adenocarcinoma (?) | Mesentery, bowel, liver, abdominal wall | 5 | 13.5% |
| Carcinoma | Kidney, thymus, mammary gland, vulva & perineum, liver & lung | 4 | 10.8% |
| Haemangioma (?) | Liver and spleen | 3 | 9.1% |
| Round Cell Sarcoma | Mediastinum, thymus | 2 | 5.4% |
| Spindle Cell Sarcoma (?) | Heart, adrenal gland | 2 | 5.4% |
| Lymphosarcoma (?) | Lung, inguinal canal area | 2 | 5.4% |
| Sarcoma | Kidney & spleen | 1 | 2.6% |
| Fibrosarcoma | Intestinal wall | 1 | 2.6% |
| Neurofibroma (?) | Omentum | 1 | 2.6% |
| Malignant Lymphoma | Liver | 1 | 2.6% |
| Thymoma | Thymus | 1 | 2.6% |
| Osteogenic Chondroma or Chrondrosarcoma | Spinal column | 1 | 2.6% |
| Lipoma | Anus | 1 | 2.6% |
| Undetermined | - | 1 | 2.6% |
| Inflammatory, Necrotic or Fibrotic changes | Mammary gland | 5 | 13.5% |
| 37 | 100.0% |
(?) - Suggestive, but identification not positive in every instance.
2. CATTLE
| Type of Tumour | Location of Tumour | No. of Cases | % Age of Total Examined Histologically |
|---|---|---|---|
| Fibroma | Mammary gland, cervix | 3 | 21.4% |
| Adenocarcinoma | Liver | 2 | 14.2% |
| Spindle Cell Sarcoma | Heart muscle | 2 | 14.2% |
| Neurofibroma | Heart | 2 | 14.2% |
| Round Cell Sarcoma | Abdominal cavity | 1 | 7.2% |
| Lymphosarcoma | Lung substance | 1 | 7.2% |
| Hepatoma | Liver | 1 | 7.2% |
| Lipofibroma | Skin | 1 | 7.2% |
| Papilloma | Eyeball | 1 | 7.2% |
| 14 | 100.0% |
D. BREED INCIDENCE.
The breed incidence in the limited numbers of cattle (20), from which samples were obtained, was as follows:—
| Breed | No. | % Age of Total |
|---|---|---|
| Hereford | 16 | 80% |
| Shorthorn | 3 | 15% |
| Jersey | 1 | 5% |
It is important to note, however, that no cases of "Eye Cancer" were included in this survey.
E. SEX INCIDENCE.
The sex incidence of the 42 samples collected from sheep was as follows:—
| No. | % | |
|---|---|---|
| Ewes | 24 | 52.4% |
| Wethers | 20 | 47.6% |
| 44 | 100.0% |
F. CORRELATION BETWEEN MACROSCOPIC AND MICROSCOPIC FINDINGS.
A fairly close correlation was obtained between the Meat Inspectors' original diagnosis and the subsequent histopathological examination, 84.6% of all suspected material submitted being found to be neoplastic. In 26% of these samples, however, the precise nature of the neoplastic change was incorrectly designated macroscopically.
DISCUSSION.
The rather low incidence of neoplastic change revealed in this survey is no doubt largely due to the fact, recorded by Belschner (1961), that, in general, our meat producing animals are slaughtered before many reach the "Cancer age" for their particular species, and this contention is further borne out by the fact that no suspected cases were detected among lambs during the course of this survey.
Although a slightly higher incidence was seen in female sheep, this was largely due to the fact that, in a limited number of cases, the genital organs were the site of the neoplastic change, suggesting that in this species at least the position is somewhat analogous to that in dogs (Moulton -1961).
The only case of Lymphosarcoma encountered in cattle was in a female, and Moulton (1961) states that this type of tumour is more common in that sex in the bovine. In the sheep series, however, one positive case of Lymphosarcoma and a second case suggestive of that condition were encountered in wethers.
The considerably higher incidence of neoplasia in cattle, as opposed to sheep, despite the rather limited numbers involved in this survey, is probably significant, particularly as "Eye Cancer" cases were not included.
Gibbons (1956) has stated that the most common tumour of cattle in the U.S.A. is Malignant Lymphoma, but this does not appear to be the case in this area of N.S.W.
As regards breed incidence in cattle, the limited figures suggest that, apart from "Eye Cancer", the incidence of Neoplasia in the three breeds represented is roughly parallel to their percentage of the total cattle population of the area.
CONCLUSION.
Results of a survey, involving the collection and examination of suspected neoplastic material from cattle and sheep in North Western New South Wales, are given and some tentative observations made in the light of these results.
ACKNOWLEDGEMENTS.
Thanks are due to the staff of the State Meat Inspection Service, attached to North West Abattoirs, Inverell, who collected the specimens, to the personnel of the Veterinary Research Station, Glenfield, who carried out the histopathological examinations, and to Mr. A. N. Harris, B.V.Sc., District Veterinary Officer, Armidale, for help and suggestions.
References:
- Belschner, H. G. (1961), "Sheep Management and Diseases". Angus & Robertson, Sydney.
- Gibbons, W. J. (1956), "Diseases of Cattle" by Fifty Seven Authors, American Veterinary Publications Inc., Evanston, III. P. 113
- Moulton, J. E. (1961). "Tumors in Domestic Animals". Univ. of Calif. Press, Berkeley & Los Angeles