Definition. Distinction from rachitis. Process of rarefaction, cell
proliferation, congestion, solution of earthy salts and fibrous
matrix, osteoclasts, Howship’s lacunæ. Dried bone light, spongy,
friable, though enlarged in repaired cases, dense, heavy. Face
lesions. Dyspnœa. Dropping teeth. Causes: microbian hypothesis,
disturbance of bone nutrition, faulty food, lack of bone salts, cellar
stables, floor on ground, malaria, cold, damp soils, city life, early
life, breed, asses and mules, breeding. Nature. Symptoms: illness,
inappetence, lifelessness, early fatigue and perspiration, stiffness,
lameness, distortions, stumbling, knuckling, arthritis, tender puffed
joints, thickened softened bones, facial swellings, narrowing of
intermaxillary space, chisel teeth, difficult mastication, shedding
teeth, emaciation, marasmus. Phosphates in urine when disease is
active. Relation to exostosis. Prevention and treatment. Hygienic,
move from cellar stable, or ground floor, secure air space under
floor, ventilation, warmth, sunshine, grain feeding, pasture, change
food, rest, salicylates, salicin, salol, phenacetin, blisters,
phosphates, bone dust, phosphorus, bitters, iron, barium chloride.
_Definition._ A form of osteo-malacia occurring in the mature as well as
in the growing horse, characterized by the absorption of earthy salts
from the walls of the cancelli and Haversian canals with excessive
production of the organic basis and cell elements and enlargement,
softening, lightness and fragility of the bones.
It differs from rachitis essentially in this that while the latter
attacks the young growing bone at the chief seats of growth, under the
periosteum and in the epiphyseal ligament, and therefore especially on
the surface of the true bony tissue, osteoporosis attacks the formed and
often the mature bone in its interior, producing attenuation of the
walls of its vascular canals and cancellar cavities and increase of
their fibro-cellular contents. Both result in enlargement of the bone,
but in rachitis this is determined largely by deposition on the surface
while in osteoporosis it takes place by expansion from within. The
further distinction that rachitis appears enzootically and osteoporosis
sporadically applies only to localities in which the latter is not
common. At different points on Long Island, in New Jersey and on the
rich soils in the Mississippi valley and on the Atlantic and Gulf
coasts, osteoporosis often prevails enzootically and has its
recrudescences like rachitis.
The process of rarefaction and softening may be thus stated. In the
Haversian canals and narrow spaces there is an active proliferation of
cells and increase of vascularity, with a gradual solution and removal,
not only of the earthy salts, but also of the fibrous matrix in the
walls of these spaces. As in the normal changes in bone, the absorption
appears to be effected through the large cells or osteoclasts grouped
around the blood vessels. In the osseous tissue, which abuts on the
vascular tissue, are to be found excavations, simple or irregular,
(Howship’s lacunæ), containing granular cells and the larger
osteoclasts. In a similar manner bone is softened and absorbed in
connection with tubercle, or the pressure of tumors, aneurisms,
actinomycosis. In case of recovery, repair takes place by the
disposition of new bone, so that the enlarged and rarefied bone may in
the end become harder than before. This applies especially to the
cancellated bone. On the articular ends of the affected bones, the
granulation tissue makes its way into and through the cartilage of
incrustation with resulting active disease of the joint.
The condition of the bone is well illustrated in the dried or macerated
specimen. Taken from a bad case in the active stage of the disease, it
crumbles under pressure and weighs as light as a sponge, whilst from an
advanced or recovered case, it is hard and resistant, and weighs as much
more than the normal bone as it exceeds it in bulk. The morbid
rarefaction usually affects the whole skeleton more or less, yet in
perhaps the majority of cases; the change is greatest in the bones of
the face, and the resulting distortions are usually symmetrical on the
two sides. It may show mainly in the maxilla, which is thickened to
twice or even five times its normal thickness, it may show in rounded,
general swelling of the nasal and superior maxillary bones and those
around the orbit, or it may involve the turbinated bones, the vomer and
even the cartilaginous nasal septum. Loosening and evulsion of the molar
teeth is common and snuffling breathing may occur as in rachitis
affecting the nasal bones of dogs and swine.
_Causes._ We are still in the dark as to the essential cause of
rarefaction of bone. There is a growing tendency to suspect a microbian
origin, and many facts are held to point in that direction. It seems to
have been unknown in England in the early part of the 19th century, and
is not noticed by Blaine, Youatt, Percivall nor other of the early
writers. In Varnell’s cases the same man had two farms not far apart and
equal in soil, drainage and stabling, stocked with horses bred from the
same parents with the same kind and amount of feed and work, yet on one
farm six cases of osteoporosis occurred, and on the other not a single
case. McNeil, in charge of street car stables, found the disease
destructively prevalent in the best appointed stables and absent from
others in the worst hygienic condition. In a superior stable with 220
horses he had 47 cases in two years, and in a fine stable with 100
horses he had 26 cases in the same length of time. In the poorer
stables, the horses bred in the same way on all kinds of soils and with
no difference in feeding nor management escaped. It is the common
experience in Europe and America that a farm or district, which has been
previously free from the disease suddenly has an outbreak in enzootic
form, and this will last for a year or two, then remit only to appear
with its old force after an interval of some years. Even during the
active prevalence of the disease on one or on several adjacent farms,
others in the immediate vicinity, and differing in no appreciable way,
geologically, hydrostatically, in buildings, food, water, general
management nor work, completely escape. Berus, Hoskins and other city
veterinarians have noticed, that it was almost the rule, that a fresh
horse put in the stall of one that had suffered from osteoporosis soon
contracted the disease.
W. L. Williams noticed on two different farms in Central Illinois, on
which the disease suddenly appeared, that for years after the
comparative subsidence of the affection there was an unusual prevalence
of spavins, splints, ringbones and other diseases of the bones. Meyer
has noticed that cases sent from Cincinnati into the country, and that
have got well, will succumb to the affection if brought back into the
city stables in which they originally contracted it.
All of this points very strongly to one of two things; either a
pathogenic germ in the system of the affected animal; or the presence of
a pathogenic microbe in the stable, water, or other part of the
environment, the toxic products of which are taken into the animal
system.
But as yet no specific pathogenic microbe has been demonstrated so that
this doctrine must still be held as a mere plausible hypothesis.
Many veterinarians with long experience in such cases absolutely deny
contagion. The hypothetical contagion undoubtedly extends slowly, and
uncertainly from animal to animal, probably, like actinomycosis, taking
place mainly through the soil, or some outside medium, rather than by
direct contact; or a special susceptibility on the part of the
individual animal may be necessary to render it effectual.
_Accessory Causes_ can be spoken of more confidently but even of these
no one, nor small group, can be advanced as essential. The process of
bone nutrition is readily disturbed by a variety of conditions, and such
disturbances may easily become the occasion of weakening the resisting
power and mayhap of admitting the hypothetical microbe to get in its
pathogenic work.
_Faulty food_ has been a favorite explanation. A lack of lime in the
soil and fodder seems, at times, to have had a baneful effect, if only,
in lowering the general tone and impairing the nutrition. Yet we see
osteoporosis on limestone soils (New York, etc.), and in animals
generously fed on grain. The same remarks apply to phosphorus and
phosphates. Their deficiency apparently contributes to the production of
the disease, and yet under other conditions, their abundance is no
barrier to its development. The excess of free phosphorus produces
osteitis and it is held by some that an over-abundance of phosphates
acts in the same way. It has been sought to incriminate a too
nitrogenous diet in some cases, and in others one too rich in fat or
carbohydrates. The many cases in Philadelphia and Pennsylvania were
mostly in animals that had been well fed and were in good condition when
attacked (Marshall).
Special food may be the direct cause, bran diet has been already noted.
Hinebauch found an acute osteitis with bone softening and arthritis in
horses fed on millet, green, partially matured and ripe. Horses
elsewhere have fed on millet, without such results, but not perhaps, in
the same environment, nor in presence of the hypothetical microbe.
Millet is not the sole nor common cause of osteoporosis, but there is
reason to suspect that it is at times an important accessory cause.
Of all prejudicial conditions none is to be so dreaded as _unwholesome
stables_. Of 200 cases reported by Berus, in Brooklyn, almost all were
in cellar stables or those with floors laid on the soil. Meyer finds
that “most all cases can be traced to an unwholesome atmosphere, or
gases arising from vaults, sewers, cellars, filthy streams, or from a
hollow space under the floor.” Harbaugh says every case was stabled in
damp, ill-drained, unventilated and badly lighted buildings. The worst
outbreak was in a basement with a damp wall, on one side, and none
suffered except those that stood next to this wall. The horses standing
on the opposite side, which was on a level with the ground outside,
escaped. Removal from a cellar stable to the floor above, put a sudden
stop to the appearance of new cases. James, of St. Louis, found 20
successive cases in a stable on a dirt floor, and Jasme, of Charlestown,
finds nearly all his many cases on earth floors in malarial regions.
_Malaria_ has been blamed, especially by southern observers, accustomed
to see the disease on the warm alluvial seaboard and river bottoms. That
this environment predisposes to the disease, by undermining the health,
is doubtless the case, but in spite of occasional remissions in the
symptoms, malarial germs cannot be set down as the constant cause. One
of the worst cases I ever saw, with every bone in the body soft, spongy
and light, developed at Inglis Green laundry, Edinburgh, where malaria
is absolutely unknown, but where the brook received large quantities of
chlorine.
_Cold_ is an undoubted factor, though the disease is most prevalent in
our warm southern states. Many veterinarians have noticed its
coincidence with rheumatism, in which cold is so often the dominating
accessory cause. Some have even suspected that it is only a modified
type of the rheumatic condition. Hinebauch found his cases of _millet
disease_ in cold basement barns, or with leaking roofs, so that the
floor and bedding were constantly wet. He found that cold always
aggravated the disease, and bad air even more so, while salicylates
seemed to have a marked curative influence.
_Damp soils_ should be named in this connection. These not only chill
the air by evaporation, and condense the cold dews at night,
contributing to produce the extremes of hot noon day and cold night
temperature, with corresponding disturbances of the bodily health, but
they favor the preservation of the infinitesimal forms of life
(bacteria, protozoa) and therefore of the hypothetical microbe of the
disease.
_City life_ is a most potent cause. Berus tells us that hundreds of
horses die yearly in Brooklyn of osteoporosis, and that if sent early to
the country a large proportion recover. The same is true of New York
City and Philadelphia. Of Cincinnati, Meyer says that he has failed to
find a case more than five miles outside the city limits, and that cases
sent to the country make a partial or complete recovery. If returned to
their former city stables, nearly all contract the disease anew within a
year.
Many cases, however, are found in the country and often within a
circumscribed area. These indicate, as in the city cases, a localized
cause, bacteridian or otherwise.
_Early life_ predisposes, the majority of cases taking place before the
sixth or seventh year, yet the disease occurs at all ages up to twenty
years and over.
_Breed_ does not seem to make a material difference, and though Shetland
ponies have acquired a bad reputation, their propensity to become fat
and soft, their too often idle, pampered life, and the confined quarters
in which they are frequently kept, account for much of the mortality.
_Asses and mules_ habitually escape, even in the South, where the latter
animal is so numerous and often so poorly kept. In Hinbauch’s millet
disease, the mules suffered more than the horses.
_Breeding horses_, male and female, have often acute attacks and die
early. The drain on the system and confinement seem to act injuriously.
_Nature._ Until we know the essential cause or causes of osteoporosis,
we must be in doubt as to its pathology. We are even debarred from
pronouncing authoritatively upon the essential identity or difference of
the various forms of softening, or rarefaction of bone. In obedience to
the clinical manifestations and structural changes, rachitis, fragilitas
ossium and osteoporosis have been separately described, but we cannot
positively say that they are not all due to one essential cause,
manifesting itself differently according to the activity of trophic
processes in the bones of the victim. In the growing foal the active
developmental processes in the epiphyseal ligament and periosteum may
determine that the symptoms shall be pre-eminently those of rickets, yet
we often see these complicated by the facial and other lesions of
osteoporosis. Both may be the result of one etiological factor, or there
may be a complex disease resulting from the presence of two. Again in
the pregnant cow in which the relaxation of the ischio-pubic symphysis
and pelvic ligaments means a profound change in the bone nutrition at
this point, the presence of the hypothetic microbe, or other essential
factor, may determine a decalcifying and fragility of the pelvic bones
generally. Again in the mature male and non-breeding female, in the
absence of the disturbing conditions of nutrition just named, the
vascular elements in the Haversian canals and cancelli may determine the
simple rarefaction and expansion of the bone which characterizes
osteoporosis. When present in the bone in any of these conditions, acids
doubtless fulfill an important rôle in the decalcifying and softening
process, but behind these it may be surmised that there is an unknown
cause or causes, which it is for the bacteriologist, chemist or botanist
to discover.
_Symptoms._ These are largely the same as in brain disease. There may be
first a period of illness, with poor appetite, lack of spirit and
energy, early perspiration and fatigue, or if at large, leaving the
herd, soon followed by some stiffness of gait and lameness, which may be
intermittent, disappearing under exertion, or shifting from one joint or
limb to another after the manner of rheumatism. Sometimes it shows in
stiffness of the neck, so that the patient finds difficulty in lowering
the head to graze; in others the back and loins are stiff and arched so
that the animal has difficulty in rising and turns slowly and painfully;
in still other cases the dorsal and lumbar vertebræ are depressed so
that the back is hollow. Even before the manifestation of lameness, the
affected limb may stand forward at the fetlock or knee, the gait is
clumsy and awkward, and the patient may suddenly stumble and fall,
showing little or no power of prompt recovery of balance. A horse, and
especially a young horse, with this habit of stumbling is always to be
suspected. The long bones of the limbs tend to enlarge or thicken, and
this is likely to be more uniform than in rachitis, and not to be
confined so much to the epiphysis. The implication of the stifle, hock
or other joint, with marked synovial distention, and mobility or
dislocation of the patella, is common and may be the earliest
manifestation of illness. The bones of the face usually show early
changes. The superior maxillary and nasal bones, beneath the zygomatic
spine and infra-orbital foramen and along the line of the molar alveoli
become especially bulging and rounded, the other facial and cranial
bones suffering to a lesser degree. In the lower jaw, also, the disease
predominates along the region of the molar alveoli, and the loosening of
the molars permits them to deviate inward so that the grinding surfaces
come perceptibly nearer to the median line, and the outer half of the
tooth is rapidly worn while the inner edge projects as a sharp cutting
ridge (chisel teeth).
For the same reason, the softening branches of the lower jaw deviate
inward, tending to still further destroy the due approximation of the
upper with the lower molars, and to diminish the breadth of the
intermaxillary space. The great thickening of the rami of the maxilla
tends still further to reduce the intermaxillary furrow.
Fractures and detachment of tendons and ligaments are common results of
the rarefaction, a portion of the bone often remaining adherent to the
tendon.
Cary gives the following statistics of fifteen cases: lame in the fore
limbs 11 (mostly shoulder), in hind limbs 11 (mostly hip and stifle),
stiff in loins 8, unable to rise without aid 3, had indented ribs 4, had
shifting lameness 8, had chronic indigestion 6; mares 5; geldings 8;
mules 2; ages were—_one_ 3 years, _five_ 6 years, _three_ 7 years, _one_
8 years, _two_ 9 years and _three_ 10 years.
When the bones are enlarged their softness and friability may be shown
by pricking with a needle, which will often freely penetrate the
rarefied bony tissue. It should be first rendered antiseptic by dipping
in strong carbolic acid.
From the first the general health fails, there is difficulty in
mastication, digestion is more or less impaired, nutrition is imperfect
and muscular flabbiness, weakness and wasting advance more or less
rapidly. In advanced cases emaciation is often a marked feature.
Examination of the urine gives valuable indications, though the results
obtained have been supposed to be contradictory. While rarefaction of
the bone is advancing rapidly the urine is charged with an excess of
phosphates in ratio with the activity of the morbid process. When on the
other hand the disease has come to a standstill and the process of
repair in the rarefied bones has begun, the absence of phosphates is no
less characteristic. A patient therefore may show greatly enlarged and
softened bones with persistent lameness, and yet the urine may show
little or no phosphate. The phosphaturia may, therefore, be made the
basis of a reasonable prognosis. Excess of phosphates indicates an
active pathological process, with an uncertain outcome, while the
absence of phosphates indicates an arrest of rarefaction and holds out
good hope of recovery.
I have long observed the same in cases of obstinate and intractable
spavins, splints, ringbones and other bone diseases. Phosphaturia
bespeaks a faulty nutrition of the bone and explains the failure of
remedial measures, while lack of phosphates in the urine, or a reduction
to the normal amount is likely to become a guarantee of improvement
under local treatment. The treatment however, must be first
constitutional to correct the condition of malnutrition and then local
to correct the osteitis.
_Prevention and treatment._ As in rachitis hygienic measures give the
most uniformly good results. The change of stable is especially demanded
from a cellar or basement stable, one with joists laid on the ground or
one with an earth floor saturated with urinary and feculent products. In
different cases an enzootic has been arrested, coincidently with the
removal of the stock to the floor above, and in others with the removal
of the filth saturated earth beneath a ground floor, and the laying of a
new floor with ample space beneath for the free circulation of air. In
the same line would be thorough drainage of the site and to carry off
liquid manure to a well ventilated receptacle. Exposure to cold and wet
is to be sedulously avoided as greatly favoring the onset of the
disease, and hurrying the milder cases into a fatal activity. Free air
and sunshine are all important and it is the universal experience that
city cases taken early and sent to dry, sunny pastures, mostly recover,
or at least undergo marked amelioration. The fact that certain cases
originate during an open air life does not invalidate this position but
merely shows that other pathogenic conditions may be too potent to be
overcome by this hygienic one.
A liberal allowance of sound grain is essential to success, even in the
case of patients sent to pasture. Those that have recovered or improved
at pasture, should be retained in the country and on no account returned
to the same city stables in which they contracted the disease. Even in
the country a different stable should be secured if possible.
Any food that has manifestly contributed to the disease, should be
withheld (bran, millet, musty or fermented food or that drawn from
particular fields).
Overwork must be forbidden, and indeed any work at all during the active
stage of the disease. The victim should also be withdrawn from breeding,
at least until it has fully recovered the normal consistency of its
bone.
In cases aggravated by cold or wet, or which show the rheumatic
propensity to shift from place to place, sodium salicylate in ounce
doses several times a day may appear to benefit, and as a germicide this
may be tried on all cases. Salicin, salol, or phenacetin may be used as
substitutes. Where the disease has been largely localized, blisters have
appeared to be beneficial.
Phosphates and phosphorus have been lauded by German veterinarians, but
in other hands, and when the morbid process was active they have proved
useless, or even hurtful. Bone dust or phosphate of lime or soda may be
freely used at any time and appears to act as a general tonic, beside
supplying lime and phosphoric acid which may possibly be availed of for
bone nutrition. Phosphorus and phosphorated oil in excess always softens
the bone and much more so when this process is already excessive. In
small doses (gr. ⅙ to ½) and after the process of rarefaction has
ceased, it is valuable in hastening bone consolidation and fitting the
patient to return to work.
Bitters, iron and other tonics are valuable in improving the general
tone and indirectly the bone nutrition.
Cary had prompt improvement in connection with intravenous injection of
barium chloride once a week for four weeks, and ½ oz. doses of sodium
salicylate thrice a day. It remains to be seen whether or not this is
generally applicable.