The dimensions of a stable will, of course, depend upon the number of horses to be kept in it, and the amount of cubic space necessary to ensure health. Nothing in the whole range of horse management, next to a proper allowance of food and water, or even on an equality with it, is so important as a sufficient supply of good air in stables, and this can only be secured by efficient ventilation and a due allowance of cubic space. Without a sufficiency of pure air health cannot be long maintained; and the number of diseases which are caused by breathing foul air, as well as the predisposition to other most serious disorders incurred from the same influence, is notorious. The gases given off in the act of expiration through the lungs and skin, as well as those generated in the decomposition of urine, faeces, etc., in the stable, are poisonous when breathed, and are irritating to the air-passages and eyes; while the food is also tainted with them, and is, consequently, less liked by the horses.

Horses kept in the foul air of imperfectly constructed stables, or in over-crowded dwellings, are never so strong or healthy-looking as those inhabiting roomy and airy places; they require more food to perform a given amount of work, are easier fatigued, and their circulation is weak. Consequently, they suffer from swelled legs, are often affected with a chronic cough, and are particularly liable to colds; and if a contagious disease, as glanders, for instance, appears among them, it spreads rapidly, and is most difficult to eradicate. And when influenza visits such stables, it always manifests itself in a more severe and fatal form, attacking a larger number of their inmates. This was well demonstrated some thirty years ago, during an outbreak of influenza at Boston, U.S.A., when the disease assumed a rather serious form. At the instigation of a medical authority - Professor Bowditch - every stable in the city was inspected and reported upon, being classified as "excellent/' "imperfect," or "wholly unfit," in respect to ventilation, cleanliness, dryness, warmth, and light. It was found that in the first-class fewer horses were attacked, and the disease was milder, and more rapidly recovered from; in the second class more were affected, and recovery was longer; while in the third class every horse was seized with the fever, the symptoms of which were most aggravated, and the rate of mortality was very high. So that, in summing up, it was found that in respect to the numbers attacked, the three classes stood to one another as 1, 3, 5.

The horse is a large animal, comparatively, with very capacious lungs and active respiration, and adapted by nature to live and thrive best in the open air. In proportion to his activity is the amount of tissue waste, and therefore of worn-out and deleterious matter thrown off from his body. There-fore, there is all the more necessity for an abundance of fresh air, and the speedy removal of that which has become deteriorated. It is in over-crowded, badly-ventilated stables, where sanitary rules are ignored, that diseases are most prevalent, and horses are shortest-lived; and when such insanitary conditions are combined with hard work, and bad or insufficient food, then we have present everything required to diminish efficiency, induce disease, and curtail existence.

It must not be forgotten that a hot stable may not be a foul one, though it very often is; nor a cold stable a well-ventilated one. On the contrary, a stable may be warm, and even hot, and yet contain less foul air than one which is cooler. But there can be no doubt that hot stables are generally foul, as the higher temperature not only usually implies insufficient cubic space and an inadequate supply of fresh air, but it also indicates more rapid decomposition of urine, litter, and other matters, and the consequent disengagement of hurtful gases, and diffusion of these in the limited atmosphere.

And even when there is ample cubic space, and the means for ensuring ventilation are present, there is often a strange tendency on the part of grooms and horse-keepers to ignore or nullify these, by excluding, in the most careful and laborious manner, the entrance of the uncontaminated air from without. They seem to have a most unaccountable and perverse liking for a hot and foul-smelling stable atmosphere, and to obtain and enjoy it they will keep windows and doors rigidly closed, shut down ventilators, or choke them with bundles of straw, pack every crevice through which air may chance to enter, with the same material, and even obstruct the keyhole. The hot, damp, and sickly smell they seem to revel in, and it is all the more enjoyable if it be so impregnated with the fumes of ammonia as to tickle the olfactory nerves of the chance visitor, and bring tears to his eyes. Such a sweltering, suffocating atmosphere cannot be good for man or beast. And as evidence that it is pernicious to the mistaken individuals who indulge in it, we have but to look at their pale, pasty countenances, and the general unhealthy condition of many of them; while as to their unlucky charges, the proof that they suffer much more is to be found in the fact, that they are the most remunerative patients the veterinary surgeon has, as they most frequently, and for the longest periods, require his attention.

The amount of gaseous and organic impurity in the air of stables can only be determined by chemical analysis. The most dangerous of the gases is the carbonic acid given off by the lungs and skin, and which, when more than a most minute percentage is present in the atmosphere, is injurious, and even poisonous; while the amount of it in stables is also an indication of the likewise hurtful organic matter suspended in the atmosphere of these places. The carbonic acid in well-ventilated stables should not amount to more than .6 per 1,000 cubic feet of air; if it exceeds this, then ventilation is defective, and the horses are inhaling an impure atmosphere. How impure and destructive this may be, in some instances, is shown by the fact that 1 per 1,000 renders the air of a room "odious and unwholesome," and offensive and oppressive to the persons breathing it; while in some stables, the air of which has been examined, it has been found as high as 2.65 per 1,000, and even 7, 8 1/2, and 17 per 1,000 in stables on the Continent.

It is astonishing that horses can exist at all in such places; and doubtless they escape speedy death by being out at work in the open air for some hours, in the course of the day.

The other objectionable ingredients in the air of stables are the ammonia, organic matter, and moisture exhaled from the lungs and skin, or evaporated from the urine, etc.

The amount of cubic space necessary for each horse in a stable will depend to some extent upon the construction of the stable and the means for ventilation, as well as the size of the horses. It has been estimated as high as 2,000 cubic feet per horse, and sometimes it is found to be as low as 500 feet. But while it may be taken at about 1,200 to 1,500 feet, it certainly should not be less than 900 cubic feet per horse.

Too much cubic space, while it is very advantageous in summer, and even in winter if the stable can be kept warm by artificial heating, or the horses made comfortable by clothing and leg-bandaging, is yet objectionable at the latter season if warmth cannot be ensured.

It has been laid down for guidance, in building stables for draught horses, that the internal measurements should allow at least a distance of 18 feet between the front and rear walls, and a width of not less than 6 feet for each single stall, to provide sufficient air space (about 1,200 cubic feet per horse). If the stable has a loft overhead, the height should be 12 feet, but if open to the roof, sufficient capacity may be afforded within the angles of the slopes.

As to the internal arrangement of the stable and the ground area per horse, this again must depend upon circumstances, to some extent. The ground area has been estimated at from 90 to 100 feet; but for large draught horses it should be a little more than the latter dimension.