Causes: Caries, vertebral diseases and lesions, neoplasms,
actinomycosis, tubercle, abscess, organizing exudates, parasites.
Melanoma, cholesteatoma, sarcoma, papilloma, lipoma, glioma,
chrondroma. Symptoms: advance insensibly, or by sudden leap with
exudate, spasm, paresis, transverse, senses clear, muscular atrophy,
advance from behind forward. Cervical, dorsal, lumbar lesions.
Bladder, sphincters, tail. Symptoms increased by movement. Treatment:
according to lesion. Tumors, hopeless. Blood clots, Actinomycosis.
Analgesics. Electricity.
_Causes._ Slowly progressive compression of the cord has been already
noted as resulting from caries and other diseases of the vertebræ. It
remains to notice such as result from the growth of tumors and other
neoplasms in the spinal canal. In the horse these are commonly melanoma
(in white horses), sarcoma, encephaloid, papilloma, cholesteatoma, and
osteoma; in cattle, beside tubercle and actinomycosis, have been found
sarcoma, lipoma, osteoma and glioma; and in dogs sarcoma and
chondro-sarcoma. Chronic abscesses may be met with in all animals
determining the same class of symptoms by slow pressure. In the same
manner exudates in process of organization contract, and are liable to
compress the myelon. Cadeac draws attention to a calcic degeneration of
exudates in the dura mater of the dog (ossifying pachymeningitis), and
of ossification of the intervertebræ cartilages with vegetations on
their surfaces. Parasites also exercise a growing pressure, especially
echinococcus, in cattle cysticercus mediocanellata, in sheep and dogs
cœnurus, and in pigs and dogs cysticercus cellulosa.
=Melanoma.= In gray and white horses, with disseminated melanosis, the
spinal canal is often involved, the pigmentary sarcoma appearing in
small formations and sometimes large enough to determine injurious
pressure. In the early stages these may cause stiffness and lameness
referable to particular muscles or groups, varying in situation, even as
to the limbs affected, at successive dates, and finally merging into
paraplegia.
=Cholesteatoma= is less common than in the encephalon, yet one is
reported by Dexler as attached to the pia mater and possessed of great
firmness, crisply crackling under the knife. It doubtless secures
accretions under meningeal exudates like those of the choroid plexus.
=Sarcoma= and =encephaloid= are usually found in connection with the
dura mater, and of small size, but numerous. They often surround the
roots of the spinal nerves, and here as on the cord exert sufficient
pressure to impair nervous function.
=Papilloma= has been found connected with the pia mater and of marked
vascularity. The author has found one in the ewe in a case of the
neurasthenia of advanced gestation.
=Lipoma= is also rare. Osseous growths are common, being favored by
sprains and injuries. All show a marked predilection for the lumbar and
last dorsal vertebræ. This may be partly explained by the liability to
injury and to disease invasion through the interlocking of the joint
surfaces of the rings. _Osteophytes_ growing from the intervertebral
cartilage are common in the dorsal region as well.
=Glioma= has been found in cattle, occupying the substance of the cord
itself and growing to the size of a hen’s egg or even of the closed
fist. The cord is gradually atrophied and paraplegia is inevitable.
=Chrondro-sarcoma= has been found growing from the intervertebral fibro
cartilage of dogs.
The _Symptoms_ may be deferred for a length of time on account of the
accommodation of the myelon to the slowly increasing pressure. When they
do become manifest, it is usually at first by insensible gradations so
that for a time their existence is questionable. Yet a case will
sometimes reach a sudden climax, by reason of a blood extravasation or
inflammatory exudate, and the signs of sudden pressure or acute myelitis
or meningitis supervene. In the absence of sudden access of trouble, the
symptoms are those of a slow increase of _motor troubles_ (local
paresis, paralysis, paraplegia), or _sensory_ (hyperæsthesia,
anæsthesia). Spasms may occur early or even later in the disease. From
disorders due to cerebral lesions the morbid phenomena are distinguished
by being paraplegic rather than hemiplegic; sensori-motor rather than
sensory or motor; local rather than general; with intelligence and
special senses clear, rather than dull or abolished; associated with
marked muscular atrophy in the affected parts; advancing from behind
forward rather than uniform throughout the body.
The area of nervous disorder points more or less clearly to the seat of
the lesion. Early implication of the fore limbs, and then later of the
hind, suggests lesion of the cervical region. Dyspnœa tumultuous heart
action, or vertigo may coincide. Tardy movements of the hind limbs,
imperfect balancing, dragging, swaying, knuckling, involuntary flexions
of stifle or hock, flexor contractions, standing on toe, cramps,
paraplegia, indicate lesion in the dorsal or lumbar region. There may be
palsy of the rectum, anus, bladder, sphincter vesicæ, penis, and vulva.
Paralysis or other nervous disorder of the tail and sphincters ani and
vesicæ, without implication of the hind limbs or quarters, may bespeak
lesion in the terminal end of the spinal cord.
With paralysis of the bladder the penis may be pendent out of the
sheath, or being retained within it, the urine may dribble constantly
into and from that cavity, and the vulva may be soft and flaccid. When
the anus is involved, the adjacent part of the rectum usually
participates becoming overloaded, the sphincter is soft and lax and
allows a constant oozing, and the exposure of the mucosa. The paralytic
tail hangs between the thighs, limp and flaccid, and becomes saturated
with manure and in females with urine.
Even in the earlier stages the symptoms are usually greatly aggravated
by compulsory movements like turning in a circle, walking up hill, or
(in dogs) up a stair, the arched back, the pendent head, and hesitating
planting of the foot suggests walking on pins. For a more exact
localization of the lesion the reader may consult the table indicating
the functions of the different parts of the spinal cord. The early
fatigue under exercise grows as in other progressive spinal lesions.
_Treatment._ In most cases this is hopeless. Tumors, bony and calcic
growths, tubercles, degenerations and absorption of nervous tissue are
practically beyond remedy. A blood extravasation may be largely
absorbed, leaving only the permanent changes in the nervous tissue. In
this time is the main element. Actinomycosis may sometimes be
successfully met by a course of potassium iodide, when, if the nervous
lesions are slight, a fair recovery may be secured. In the majority of
cases, however, the practitioner is limited to measures for palliation
of suffering by atropia, chloral, phenacetin, etc., or by nerve
stimulants like nux in small doses, or by weak currents of electricity.
In meat producing animals, it is often the best course to fatten
rapidly, or to turn over at once to the butcher.