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This article was published in 1974
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Johne's Disease in Cattle
by P.G. Honey, B.V.Sc.
In June, 1973, a Mullumbimby farmer lost six prime bullocks. Two died, two were slaughtered on the property and two were ordered to an abattoir for slaughter. Symptoms were a mild loss of condition and slightly watery faeces, Suddenly the animals would become bottle jawed and scour profusely. Once scouring began in earnest the animals would rapidly become emaciated, weak, bleached in the coat, dehydrated and finally recumbent. Death occurred about a fortnight after the onset of heavy scouring.
Small intestines contained copious brown watery contents which in some parts was bloodstained. Walls were thickened up to 6-7 m.m. and thrown into rugae like the surface of a brain. Inflammation occurred along the crests of the rugae giving the opened intestine a tiger striped appearance. Such lesions occurred generally from anterior to mid small intestine down almost to the ileo-caecal valve. There were no gross abnormalities of the ileo-caecal valves. Most visible lesions were confined to the small intestine although a few inflamed rugae occurred in the caecum, colon and rectum.
D.V.I. Wollongbar carried out bacteriology and histopathology. Smears of rectal scrapings showed up clumps of short acid-fast rods. In the small intestine the acid-fast rods were sometimes clumped and sometimes single. In the most distal part of the large intestine the organisms seemed to be fewer and less definite. Faecal smears showed clumps of acid-fast bacilli. Culture of rectal and colonic material yielded M. paratuberculosis.
Histopathology showed large numbers of organisms resembling Mycobacterium paratuberculosis infiltrating cells in the mucosa and sub-mucosa. Thickening of the lamina propria and submucosa was demonstrated with large numbers of epithelioid cells containing the organisms. Giant cells were present in the mucosa. Mesenteric lymph nodes were heavily infiltrated with epithelioid cells and some giant cells.
Some factors which may be of epidemiological significance were:- In the two animals slaughtered on the property a concurrent infestation of ostertagia was found. A property quarantined in 1937 and referred to in Seddon's "Disease of Domestic Animals in Australia", Part V., Vol 1, page 151 is adjacent to one of the properties owned by the person quarantined in 1973. The only cattle to suffer clinical symptoms were full grown adults.
Methods of diagnosis used were post-mortem, complement fixation test, bacteriology on rectal scrapings and bacteriology or faecal smears. The most accurate was post-mortem. None of the other methods was found completely consistent with post-mortem findings.