H.—29.

Gkass Tetany. While fewer blood samples were received for diagnosis of grass tetany, this disease has been given extended laboratory study during the year, particularly from the magnesium viewpoint. The results are summarized in the reports of Dr. Cunningham and Mr. Josland appended hereto. As a result of their work, Messrs. Marshall and Blake tried magnesium sulphate in drinking-water as a preventive on several farms in the Waikato, but they were not able to say whether the method was successful or not in the one season. They also carried out magnesium-sulphate inoculation in grass-tetany cases, and in the Waikato, curiously enough, Mr. Blake was successful in curing a number of cases of a subacute type, while Mr. Marshall had only indifferent success. Magnesium sulphate apparently acts as a sedative, but when acute oases do not respond to treatment as do milk - fever cases to calcium, one must conclude that magnesium deficiency is not the actual cause of the disease. So many healthy cows at that time of the year are deficient in serum magnesium that it might seem that magnesium deficiency is being given too much prominence. Biological Examination op City and Town Supply Milk Samples. Five hundred and eighty-seven samples were received throughout the year, and fourteen were repeated, mainly in an attempt to find whether affected animals had been eliminated. Number of samples received once, 587; eleven T.B. positive; 1-87 per cent. Repeat samples, 14; three T.B. positive. Johnb's Disease. Nineteen positive specimens of Johne's disease were received during the year. Twenty-five infected farms are now known. Testing with Dunkin Johnin has been attempted with some success by Messrs. Stephens and Marshall, but owners of affected cattle do not, as yet, seem to have become aware of the dangerous nature of the disease. Actinomycosis and Actinobacillosis. The field staff is taking advantage of the agglutination test for actinobacillosis, the importance of the test being clearly realized. Blackleg. Specimens were not as numerous as in past years, and the formalinized culture is proving of material benefit in conferring immunity on calves ; 42,850 doses were issued, more than half going to the Waikato. Anthbax. Anthrax was diagnosed in a farm adjoining the farm of the previous year's outbreak. Only one death occurred. SHEEP DISEASES. Three hundred and three specimens were received for the year, 163 being samples of blood for agglutination test for arthritis. Caseous Lymphadenitis. During the year the palpation of flocks commenced three years ago has been continued. While the South Island flocks under trial showed a considerable reduction in numbers affected down to the vicinity of 2 per cent, below which it is difficult to reduce the disease, the North Island flock under investigation has risen from last year's 2-7 per cent, almost to its first-flock percentage of just over 3 per cent. There has been a change in glands affected in the North Island flock, for the majority of the abscesses palpated this year have been found in the supramammary glands. This fact, taken in conjunction with a very much lessened incidence of caseous lymphadenitis in dry ewes, suggests that two factors operating in the North Island flocks under observation are of greater importance than the shearing factor. These are crutching and lamb carriage of the disease from ewe to ewe by mismothering at docking. Crutching wounds must become infected in places other than yards and sheds, and possibly in the more heavily stocked areas some consideration must be given to sheep night camps. Enzootic Ictektjs. Liver elimination tests in this condition have shown that the liver is not functioning as it should. Manv sheep have died recently from enzootic icterus in the Waikato, and in each case there has been some suspicion of eating of ragwort. In a few of these icterus cases there is a tendency for soreness of the lips and legs to occur, evidently from the action of sun's rays on the bile sensitized skin. Pulpy Kidney and Ciecling Disease. Pulpy kidney and circling disease specimens have been received for diagnosis, but no experimental workhas been undertaken since Mr. Gill's departure. Circling disease has been much more noticeable this autumn, due possibly to the abnormally dry conditions. Contagious Ophthalmia oh Pink-eye. This disease in sheep was given attention, but no definite organism could be shown to produce the condition. Every organism culturable was tried with negative results. Tears were of course able to produce the disease in other sheep, but filtered tears were negative. Tears, unfiltered or filtered, placed intravenously into sheep did not produce the disease. Sheep sprayed up the nostrils with diluted tears 1-100 became infected. Sections of cornea showed a gram positive diphtheroid type of organism, which appeared in culture but which did not set up inflammation experimentally. No richsettia bodies could be demonstrated. It was noticeable that the weather conditions were such as to produce a dry pasture, with a deficiency of accessory food factors such as Vitamin A, which it is suggested may be a factor in the spread of this disease. Calves and rabbits did not become infected experimentally.

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