206 GESERAL ARTICLES.

the pleura, especially in upper parts of lung; tracheal mucous mem­brane red and inflamed. Lymphatic glands of chest swollen, inflamed, and cedematous. Spleen, liver, and kidneys little altered. Ollly a little effusion in abdomen. First three stomachs normal; fourth inflamed, its mucous membrane swollen, red or bluish-red in colour, and with one incipient ulcer. Small bowel acutely inflamed, its mucous membrane a little swollen, and all blood vessels injected; large bowel much less so, and worst at c~cum. Mesenteries injected and blood-stained; all lymphatic glands swollen, cedematous, in­flamed, and pinkish in colour. Spinal fluid much increased, spouted briskly when tapped; cord normal throughout, but inner covering of brain highly injected and ventricles full of fluid. The lining mem­brane of the nasal chambers was bluish-red and congested. Mouth and throat normal; bones, marrow, and joints normal.

Many other strains of virus have been tested by means of experi­mental inoculations into goats and sheep, death ensuing more or less rapidly, according to the age and purity of the cultures used. The post-1Ilortem appearances are almost identical with the two above described, and vary a little only according as the germ exerts its virulence mostly upon the thoracic or upon the abdominal viscera. The micro-organism is readily picked up again from their tissues, and maintains its virulence for fresh animals.

THE ETIOLOGY AND PROPHYLAXIS OF EQUINE OSTEOPOROSIS.

By HAROLD B. ELLIOT, M.R.C.V.S., Hilo, Hawaii.

IN a previous article contributed to this journal l I discussed this disease from a strictly clinical standpoint. Although nearly ten years have elapsed since then, and the disease has been described by several careful and scientific observers in various and far apart countries, and de'ipite much excellent laboratory research, the solution of the etiological problem involved is so little advanced that this method of treatment is still the only possible one. 111 this article the theory of infective causation was, for the first time, argued in extenso and logically presented, and because it has been frequently quoted in current veterinary literature it seems desirable, in the light of a more mature experience, to correct and amplify some of the statements and opinions expressed therein.

Osteoporosis is of almost world-wide distribution, is the source of a large annual mortality, and inflicts severt' economic losses in those areas in which it is prevalent. The consultant is exposed to an apparently insuperable difficulty, and is compelled to the most distasteful task of admitting his inability to advise sllccessful measures either of prophylaxis or therapeutic treatment. It is, therefore, very necessary that every hint, every fragment, however small, of knowledge should be published and made common property.

"The result of my clinical observations has convinced me that the theory of the dietetic origin of osteoporosis is erroneous, and founded

1 Yol. XII., Part 4, p. 300.

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upon a mistaken conception of the pathology of the disease, and my opinion is that it is primarily and wholly one of locality, in other words, a climatic disease." 1 The latter statement requires modifica­tion, both in a general sense and in its relation to these islands. The progress of modern science has considerably qualified our use of such words as ., climatic" in connection with disease; we now know that other factors are usually needed to complete the disease-cycle; that excess of heat or cold, humidity or dryness, are merely contributory causes which encourage the propagation and growth of these factors. My correspondent (the late Captain M. H. Hayes), W. Robertson, and others have noted the existence of osteoporosis in countries where the atmospheric conditions are dry and the rainfall very slight. Also, since the establishment of a veterinary department by the Board of Agriculture in this territory, we have learned that, if this disease is most frequent in the wet belt on the island of Hawaii, severe outbreaks may, and do, occur in those drier districts which were formerly supposed to be exempt. Exceptionq,l humidity, there­fore, is not an invariable, or even a necessary, factor in the production of osteoporosis. So far as locality is concerned, we can only say that a well-marked local preference is one of the attributes of this disease, and that in this, and in other respects, it exhibits undoubted analogies with the infective disease, tetanus.

"The first stages of osteoporosis closely simulate the incubative period of microbic infection; it frequently follows accidental injuries and operath'e wounds __ it is endemic in certain stables and pastures without apparent cause; many circumstances support the belief of the laity regarding its contagious nature; the pathological lesions are not merely local but are generalised throughout the system; and the occurrence of the disease is practically uninfluenced by differences of diet, labour, stable management, hygienic surroundings, age, sex, or temperament. Only bacterial pathology affords us analogies like­wise independent of these extraneous circumstances."

In the above brief summary are contained the principal arguments for the infective, and against the dietetic, theory of the origin of the disease-the only theories that appear worthy of discussion at the present time. In the first sentence the word" latent" might be more correctly substituted for" incubative." The second sentence is pur­posely emphasised in order to draw attention to a fact that has seemingly been overlooked by all other writers upon this subject except one, the late William vVilliams. Speaking at a meeting of a local veterinary association in Great Britain, he instanced among pathological problems that awaited solution the relationship of wounds of the feet to osteoporosis. This remark will probably be found in an after-dinner speech reported in a number of the VeterinarJI Journlll about the year 1898; as many of my files are missing I am unable to verify my reference as to date or place, and it only lingers in my memory because, having previously noted the same thing, it was therefore deeply impressed upon my mind. I have seen in my practice, during the last thirteen years, very many cases in which symptoms of this disease have declared themselves immediately after recovery from wounds-cases where the connection was so apparent and unmistakable that it could not possibly be overlooked. In this

1 Vol. XU., Part 4, p. 300.

200 GENERAL ARTICLES.

respect injuries to the foot, particularly aggravated cases of" picked up" nails, are the most dangerous. Now, I do not say that this relationship is a necessary element in the production of osteoporosis. On the contrary, even an exhaustive examination into the past history of many cases does not reveal to us evidence of noticeable injury; nevertheless, it is well to remember that the development of the symptoms is comparatively slow, that minor injuries or abrasions are very liable to be forgotten by the time the disease is recognised; and we know also that, in other diseases dependent upon wound infection, the lesion which affords a gateway to the invading organisms is often so small as to be almost imperceptible.

Supposing we take this point as proved, are we then to assume that the identity of osteoporosis with the class of infective diseases is a necessary corollary? I t would be with extreme diffidence that I would take up this position, but, reasoning from analogy, it would seem to be a fair presumption. We do not know of any non-specific disease that arises from simple wounds unattended \vith the accom­paniments of shock or ha::morrhage; certainly we know of none that causes grave constitutional disturbance extending over a prolonged, chronic, and incurable course. Admitting that this is possible, we have to seek the cause in wound-irritation, enforced idleness, probable change of diet during this period, or a combination of these circum­stances. If this were the case the disease would surely be well known and of great frequency in every country, for these conditions do not show much material difference wherever we may travel. Further, in osteoporotic areas we would expect to find the disease common to all stables; but this is not so, some stables being entirely exempt from its ravages. If I dwell somewhat insistently upon a point so little recognised by other observers that, but for the support of so eminent a clinician as Professor Williams, I would hesitate to accept my own experience as evidence, it is because, if it exists, it must be recog­nised as a most important consideration in an examination into the etiology of this disease.

We have now to consider whether direct transmission is possible from one living animal to another. The evidence on this point is conflicting and unsatisfactory, but after a thorough and impartial review of my own experience I am inclined to the belief that the danger of such transmission is small, and very probably non-existent. I t is by no means unusual to see an osteoporotic wreck dragging out a painful and weary life in the midst of a crowded stable, feeding from the same mangers and drinking from the same watering­trough with the other animals, but without any spread of disease. On the other hand, we meet with many instances that suggest contagion; but there is always the haunting doubt that they are merely coincidences, and this appears to me to be the correct explanation.

Travelling along these lines, and taking a good deal for granted, we are gradually forced to certain logical conclusions :-

(I) That the exciting cause of osteoporosis is a toxic, ubiquitous bacterium, resembling the bacillus of Nicolaier in its habits, dwelling in the soil of pastures and the dust of stables.

(2) That the hypothetical intermediary host of Hutcheon, if it exists, is not a winged insect, and is incapable of moving beyond a

GENERAL ARTICLES. 209

very limited radius; osteoporosis, therefore, will not be found to be allied to the infective trypanosomiases.

(3) That the equine species are possibly accidental hosts, and are endowed with a certain degree of immunity, which may be lessened by conditions regarding which our knowledge is very incompJete.

(4) That infection in many cases takes place through wounds and abrasions, though we have reason to believe that there are other methods of transmission.

(5) That the difficulty in finding the bacteria in the animal body suggests that they are few in number, of feeble growth, or multiply slowly; and that their habitat may be discovered, not in fluid or osseous, but in nerve or connective tissues or some unexpected location.

(6) We may further speculate that the destructive changes in the bones are the result of pernicious activity on the part of the osteoclasts under the stimulation of toxic influences.

The reader who may be inclined to regard the foregoing paragraphs too seriously is. reminded that they are pure guess-work, incapable of proof in the 'present state of our knowledge of the pathogenesis of this disease, and that they are simply an attempt to frame a theoretical hypothesis that fits in as far as possible with the clinical evidence recorded, and presents the least difficulty in acceptance.

Mr W. Robertson,! a firm believer in ' the contagious nature of osteoporosis, finds the recoveries that result from change of sur­roundings an awkward obstacle to overcome. These recoveries are frequent, but by no means invariable or certain, and do not appear to be connected with dietetic changes. Moreover, we cannot look upon this as a decided argument one way or the other, because it is well known that both infective and non-infective diseases of great chronicity are benefited by such changes.

The history, from 1896 to the present time, of the larger stables in those districts in the wet belt of the island of Hawaii vividly illustrates the contradictory phases in the occurrence of osteo­porosis, and the difficulties which the clinical investigator has to con'tend with in endeavouring to formulate a reasonable working hypothesis.

The first of these, the Hilo Sugar Co., has two large main stables sheltering about ISO animals. These animals may be roughly divided into three classes-large imported mules used in waggons and for ploughing and cultivation, small native pack-mules, and a few harness and saddle horses. Up to the year I899 both of their stables were literally devastated by the ravages of this disease, a considerable percentage of the victim? being among the more expensive imported stock. About this time I made the unexpected discovery that bran was being fed in variable amount, depending upon the quantity of barley on hand, and that at times the ratio of bran to barley was as much as two of the former to one of the latter. This, of course, only happened occasionally and for a few days, but it seemed to be of sufficient importance to recommend entire discontinuance of the use of bran. This recommendation was adopted, and since then only one case of osteoporosis has been noted in their stables. In the years 1903-04 the stables were rebuilt on an excellent plan, and

1 "Journal of Comparative Pathology and Therapeutics," Vol. XVIII., Part 2.

210 GENERAL ARTICLES.

further changes in the feeding introduced-green forage, molasses, and about 3 per cent. of bran per diem being added to the food­scale, and the quantity of hay reduced. Here we have a duplication of Captain Lane's experience in South Africa, namely, a simple change of diet followed by cessation of disease. But the experts employed by the Colonial Government were unable to repeat the successes of the military veterinary surgeon, and, unfortunately, it must be confessed that I have not been able to repeat my own solitary achievement in this line.

Driving in a northerly direction along the coast we come to the stables of the Onomea Sugar Co., who own 200 animals of the same nature and employed in the same work as those described. The occurrence of the disease in their stables has followed a very typical course-isolated cases at varying intervals with occasional small out­breaks during which three or four animals become affected simul­taneously. Recently their cases have been of a more acute type than is usual in this country, with a tendency to spontaneous fracture. The erection of good stable buildings, perfect from a hygienic stand­point, has had no influence in checking the disease. For many years no bran was fed to their stock, but about 1904 larger quantities of green forage, molasses, and a limited amount of bran were added. The dietetic changes cannot be said to have made any difference one way or the other.

The other plantations within this area have all suffered more or less loss from this cause, but not to the extent of the two already mentioned.

I t is a remarkable fact that the only large stable in these districts that has escaped the ravages of the disease is also the only one that is riot a plantation stable. The Volcano Stables and Transportation Company are a large corporation whose main premises are situated in the town of Hilo. They employ about 250 animals, mostly horses, in the usual work of a livery and draying business. Of these animals, some were imported from the mainland, others purchased from the ranches on this island. The latter are fairly well bred, raised at an elevation of several thousand feet, and when brought to us are young and, as a rule, unbroken. The work demanded from these animals, old or young, is often excessive and very irregular. They have been exposed, during the period of my connection with them, to every conceivable variation of diet, within the limitations of the country, that could possibly be made. Long journeys over rough and danger­ous roads, under the whip of indifferent drivers, peculiarly subject them to all the vicissitudes and accidents of equine life. N everthe­less, in spite of susceptible type and age under what would appear to be a most provocative environment, and although every case of disease passes through my hands, I have yet to see the first case of osteoporosis among their animals.

Outside of the big stables osteoporosis is frequently met with among the horses of Japanese stage (char-a-banc) proprietors, animals belonging to plantation labourers, and in the private stables of white residents.

During an interval of four years (1902-06) we enjoyed a period of unusual quiescence, very few cases being presented, but since then there has been marked increase in number and severity of type. On

GENERAL ARTICLES. 2II

the whole, however, I see much less of this disease than in the early years of my practice here.

Spontaneous recovery is by no means rare-one of my own driving horses, a well-bred gelding, being a notable example of this. Diag­nosis of osteoporosis is reasonably certain in young horses exhibiting metastatic and intermittent lameness, progressive loss of condition, and easily induced fatigue. The majority of cases presenting these symptoms develop -pathognomonic enlargement of the facial bones eventually, but quite a number regain normal vigour and soundness. Even after considerable invasion of the osseous tissues recovery may take place. but is so unusual that I have only seen three instances in which this has happened. We have no knowledge of the circum­stances that govern these recoveries, and can only suppose that these individuals possess a high degree of resistance" or immunity.

We may also note that in serious outbreaks of osteoporosis we find concurrently very perplexing and apparently unaccountable cases of obscure paralysis and disease of the nervous system. As these are not met with at other times, we may attribute them to osteoporotic infection. Implication of nerve tissue is also detected in well-marked cases of osteoporosis, and is occasionally manifested by very peculiar symptoms. I can remember one aged, osteoporotic wreck who, when urged in a forward direction, would' subside upon his haunches, slightly elevate the fore part of his body, his forelegs moving with a rapid, circular, "tread-mill" action, the toe of the foot just brushing the ground at each revolution.

When we come to the question of prophylaxis we are reluctantly compelled to admit that we are but little wiser than we were fifty years ago. The following tentative suggestions are offered :-

(a) Proper disposal of carcases, preferably by cremation. (b) Thorough disinfection of premis.es, paying particular attention

to floorings. (c) Change of pasture. (d) Such alterations in diet as the consultant may deem advisable. I do not express any opinion as to the disposal of the living animal

infected with osteoporosis excepting that isolation is unprofitable, and that it is desirable, both on humane and economic grounds, td destroy cases showing evident incurability.

My therapeutic experience is that of other obseryers, namely, that no medicinal agent appears to exert any beneficial effect on the course of the disease. I have seen the development of the symptoms arrested twice in the same animal by change of location; but, now that we are aware that osteoporosis is not confined to any particular districts, the wisdom of advising this treatment is questionable. Whilst, as I have before pointed out, I do not attach much import­ance to the possibility of direct transmission, if an outbreak of the disease should occur in the neighbourhood of the place to which an affected animal has been sent it would be difficult to assert that it was merely coincidence.