FOOT-ROT

Press, Volume LXXI, Issue 21464, 4 May 1935, Page 20

FOOT-ROT

AMERICAN EXPERIMENTS MOST EFFECTIVE TREATMENT The results of a three-year study of foot-rot in sheep are contained in a bulletin Issued recently by the Montana Experiment Station, with the Montana Livestock Sanitary Board co-operating. As the trouble is so general in New Zealand flocks the American investigations should be of value.

While foot-rot is an old disease, recognized for nearly 250 years in fact, and previous experimental work has been done on it, its appearance during the last ten years in certain sections of the range country, where control is difficult due to the large numbers of sheep involved, led to its further study by the Montana Station. The experiments were conducted along three lines: (1) to develop further knowledge as to the cause: (2) to find out how long pastures, corrals, etc., remain infected with the disease; and (3) to determine the most effective treatment, especially under range conditions. Foot-rot develops, as is well known, in sheep running in continuously wet pastures and corrals, but the Montana experiments proved that such an environment is only a "predisposing factor" in the development of the disease. The moist earth tends to make the feet of the sheep soft and susceptible to infection, and the mud getting between the toes creates an irritated area, which opens the way to infection, but it takes something more than wet pastures to cause footrot; there must be present in the soil an "infective agent." A previous study conducted by Mohlcr and Washbun ot the U.S. Department of Agriculture resulted in the conclusion that the bacterial cause of foot-rot was Actinomyces necrophorus. The deduction made from the recent Montana work is that while this is the primary cause of the disease, there is also an other factor involved which they have been unable to discover. This conclusion was based on the facts that A. necrophorus is constantly found in foot-rot lesions; that pure cultures of it were obtained from lesions on the foot of a lamb that developed the disease after being placed in a wet pasture with sheep affected with footrot; but on the other hand the disease could not be reproduced in sheep either by direct inoculations or by exposure to soil that had been repeatedly inoculated with cultures of A. necrophorus. Infected Soil From the second part of the experimental work, that of determining the persistence of the infection in the soil of pastures and corrals, the following deductions were made: Healthy sheep regularly develop foot-rot when placed in a heavily infected wet pasture, after an incubation period of 10 to 14 days. Open corrals on well-drained land lose their int'ectivity within 15 days, it the soil is allowed to dry. and within 30 days where the soil is cont:.nuously wet. In a well-drained irrigated pasture, the infection will not persist through an ordinary Montana winter, that is, four months of freezing weather. In a heavily infected sub-irrigated swamp pasture, the infection may persist from one season to the next. A heavily inflected, well-drained, irrigated pasture loses its infectivity

• very rapidly when allowed to become > dry. , The object of the experimental work in treating foot-rot was to find out which of the several methods of ' treatment was the most effective and to establish some standard form of ' application under both range and farm ; conditions. Tests were made win, three medicinal agents: (1) A cold saturated (30 per cent) solution of cop- > per sulphate; (2) antimony trichloride [ (butter of antimony); and (3) a 1 per 1 cent, solution of sodium hydroxide, i Of the three, the saturated copper suli phate solution was found to be very much superior to the other two and entirely satisfactory in the treatment \ of the disease. However, because such large amounts of the 30 per cent, cop--1 per sulphate solution would be ro- ' quired in treating range flocks, experi--1 menls were also made with a 10 per 1 cent, solution, but the results showed [ that it could not be depended upon to : cure in one treatment. While a 20 1 per cent, solution was not tested, the authors of the bulletin suggest that i probably a solution of this intermedi- • ate strength might prove as effective . as the saturated solution. 1 Method of Treatment The saturated copper sulphate solu- [ tion was used cold and the results

fhow that it is not necessary to keep the solution hot when using it, as lias heretofore been the practice, which eliminates one of the difficulties attending this method of treating the disease in range sheep. The investigators also recommend that the treatment be applied by having the sheep stand in a trough containing the solution, instead of dipping each foot separately into the solution. The use of tlie trough not only saves time but adds to the effectiveness of the treatment because the weight of the sheep spreads the foot out and ex-

poses more of the diseased area to the solution. The bulletin emphasises the necessity for the proper surgical preparation of the feet before treatment is administered. The necrotic tissue should be removed and all the affected area exposed even when it involves the removal of a large amount of horn, for, the bulletin states, "where there are extensive lesions, the operator need not hesitate to remove a large amount of the horn and expose the sensitive tissue of practically the whole foot," because "within a week or less sufficient healing takes place to enable the sheep to use the foot." ELECTRIC STUNNER FOR PIGS TRIAL IN CANTERBURY FREEZING WORKS An electric stunner for use in the killing of pigs is to be given a trial at the Kaiapoi freezing works of the North Canterbury Sheep Farmers' Cooperative Freezing Export and Agency Company. Ltd. This announcement was made by Mr J. H. . Blackwell, chairman of directors of the company, during an address to a gathering of farmers at the works yesterday afternoon. This method of stunning is already in use in at least two other South Island freezing works. Various methods have been used over a long period of years, perhaps the best known being shooting, and stunning with a hammer. The electric method of stunning is a modern development which has been strongly advocated in some quarters. Apparatus resembling earphones are used. This is placed over the head of the pig, and through it 'an electric shock is passed. The only drawback to the system is that care has to be exercised in the power of the shock given. Too little or too much affects the pig's condition for later handling. The electric stunner is to be given a trial at this works at an early date.