Germain gives the above symptoms as characteristic of the mode of development of the disease in French and Algerian horses imported into Tonquin, and his description, written several years ago, is fully confirmed by more recent observations. Since Tonquin was taken over by the French, however, improved methods of culture have resulted in the production of better cereals and forage; the fodder plants have been vastly improved, to the great benefit of imported animals.
In the goat, the disease shows some slight peculiarities. Thus, in the second phase, during which goats and sheep suffer so markedly from lameness and pain in the bones, goats often walk on the knees. The disease, however, is uncommon in these animals. The phase of osteoclastia is also less marked and fractures are rare, because the animals weigh less and also because they are less exposed to falls and violent shocks. The bones, nevertheless, are extremely fragile and fractures may be produced at will.
Osteomalacia, on the other hand, is always well marked.
Regarding the development of the disease in pigs, we may repeat what has just been said respecting the goat. Walking on the knees is often one of the first signs, fractures are somewhat rare, and the period of softening and deformity is always very noticeable.
Course. The development of the disease is slow, lasting from one to three months as a rule, and is little influenced by hygienic conditions. Good milking cows, however, seem to be most frequently attacked, probably because of the great losses of nutritive material which occur through the milk. The calves borne by such animals are often rachitic. Oxen are less commonly attacked. Horses rarely suffer from the disease in France, but frequently in Tonquin. Pigs reared on very poor soil seldom escape attack.
Fig. 7.—Osseous cachexia: softening of the maxillæ.
If treated from the beginning, or even before the second phase has become well developed, the disease may be cured, but after this period little improvement need be expected.
Causation. The problem of why osseous cachexia occurs has naturally given rise to numerous explanations, some plainly inadmissible, others, however, of greater or less plausibility.
The fact which, from the earliest times, appears to have attracted most attention is the relation defective nourishment bears to development of the disease. In Norway, as early as the year 1650, the plant known as sterregraes (which renders animals dull and heavy) was thought to be the cause of the disease; two centuries later, in 1846, the Anthericum ossifragum was similarly regarded. Zundel, in 1870, claimed that the Germans first referred the development of the disease to chemically incomplete forms of nourishment. This opinion seems fully confirmed by the remarkable observations of Germain on European horses imported into Cochin-China, and it is finally placed beyond question by the work of Cantiget. Basing his researches on analysis of the soil, he proved that osseous cachexia only occurs in cattle depastured on land which is too poor in phosphoric acid and calcium phosphate, and that it can be banished by enriching the soil with suitable manures up to a point when the proportion of phosphoric acid becomes normal. In good land, suitable for raising cattle, the proportion of phosphoric acid, according to the best exponents of agricultural chemistry, should not fall below 4,000 kilograms to the hectare. Cantiget and Brissonet have shown that where the soil contains less than 1,500 kilograms to the hectare, osseous cachexia is almost permanently present. As soon, however, as this proportion is raised above 2,000 kilograms by suitable culture, the losses diminish, and the cachexia finally disappears.