SPINAL CARIES. TUBERCULAR OR OTHER INFECTIVE DISEASE OF THE VERTEBRÆ.
Spinal caries in old horses, sprains, fractures, infections; caries often confined to articulating processes: anatomical form: Axoido-atloid caries from poll evil, concussions, fights, rachitis. Tubercle of bone and intervertebral cartilage in cattle. Symptoms: distortion, stiffness, rigidity; stands day and night, sensory and motor paralysis: localization of lesion; dyspnœa; spastic palsy back of lesion; effect on tail, sphincters. Diagnosis: progressive tenderness and stiffness of spine, distortion, localized exaltation or depression of nervous function, osteoporosis, rachitis, caries, tubercle, melanoma, abscess, infectious disease. Treatment: Sling in narrow stall, good food, pure air, sunshine, tonics, phosphates.
As seen in the human subject spinal caries is usually tubercular and is known as “Pott’s disease.” As seen in old horses it appears to be rather a result of other infections, especially purulent, and may have started in connection with traumatic or mechanical injuries to the bones and ligaments. In such cases I have seen it repeatedly in hollow backed horses in which the line of the spine descended abruptly and extremely from the withers and rose again to the sacrum. The distortion was so great that the back appeared as if it could barely sustain the weight of the animal and yet the patients were kept at work and proved useful for light driving. Post mortem examination showed extensive caries and suppuration of the vertebral bodies, confined, however, to one or two segments as if due to a mechanical lesion. In the region of the loins it is much more likely to affect the articulations of the vertebral rings, because of the manner in which these are wedged into each other when the spine is pressed downward. In the neck where the normal movement is so much freer such injuries are much less common. Caries affecting the articular surfaces of the axoido—atloid joint is by no means uncommon. It may follow poll evil, or injuries sustained when a horse runs against a wall, or in the fights of bulls or rams. Disease of the vertebræ may be of the nature of rachitis occurring in this case in early life.
In cattle the disease is liable to be tubercular in which case, not only is the bone invaded but the morbid process extends to the intervertebral cartilage and projecting, presses on the spinal meninges and cord. It may even encircle the entire spinal cavity and strangle the cord. If the pus should extend downward it may form abscess under the spine, and rupture into an internal cavity or externally.
Symptoms. Injuries and disease of the vertebræ may last for a length of time without implicating the spinal cord or nerves. They may then cause only distortion, with stiffness or rigidity of the spinal column. When, however, the displacement of the injured, carious or tubercular bones, the distension of the abscess or the increase of the hyperplasia leads to pressure on the nerve roots, the meninges or cord, nervous symptoms are likely to be developed. Compression of the nerve roots—sensory or motor—may cause sensory or motor paralysis or both, limited to particular areas the outline of which will point to the precise seat of the lesion. If in the recti of the head and other muscles of the neck, it points to the anterior cervical vertebræ. If in the fore limbs, it points to the posterior bones of the neck. The implication of the diaphragm would incriminate the fourth and fifth cervical vertebræ. If in the crural muscles or those of the quarter and thigh, the lumbar vertebræ must be looked to. The implication of the nerves of the back, while impairing the functions of the intercostal and abdominal muscles, produce less marked symptoms than when the limbs are involved.
When the disease extends deeper so as to implicate the meninges and especially the cord, there is evidence of impairment or interruption of conduction in the cord in addition to the simple involving of the nerves that emerge at that point. Thus serious disease or pressure on the cervical part of the cord in front of the fourth vertebra will make respiration difficult or impossible and speedy asphyxia may ensue. The paralysis of all parts behind the lesion is overlooked, in view of the fatal nature of the paralysis of the intercostals and diaphragm. If the interruption of conduction is incomplete there may be spastic paralysis and hyperæsthesia in the limbs and trunk back of the lesion.
If the dorsal cord is involved so as to render conduction imperfect there will be at first imperfect control of parts posterior to the lesion, and when still further implicated, flaccid or spastic paralysis, especially of the hind limbs and tail. When it implicates the lumbar region in addition to the paralysis named for the dorsal, there will be incontinence of urine and even relaxation of the anal sphincter. In a case of acute tuberculosis in a cow, supervening on an ancient tuberculous lesion, as seen by the author, there were imperfect control of the hind limbs and uncertain gait, with tenderness of the dorsal region as if the animal had sprain of the back.
Diagnosis of these cases of vertebral disease may not always be possible in the early stages, yet the symptoms of progressive tenderness and stiffness in the region of the spine, the distortion in some instances of the spinal column, the subsequent appearance of localized motor and sensory symptoms, and later still the spasms or spastic paralysis in all parts behind the seat of the lesion, will be strongly suggestive of such a disease. When indications exist of osteoporosis, rachitis, or tuberculosis, of caries, abscess, or infectious lesions of the cervical or dorsal spinal region, the inference is still stronger. Then if reaction occurs under the tuberculin test, or if the urine contains an excess of phosphates in the herbivora, the case may be diagnosed with certainty.
Treatment. This will rarely be admissible on account of the expense and uncertainty of result. Some meat animals may be killed for food. If otherwise, keep in narrow stall where the animal cannot turn even the head, feed from moderate level to avoid movement of the spine by the upward and downward movements of the head. Gentle brushing is useful as a means of cleanliness, and of toning up the muscular system. Nourishing food of an easily digestible kind is essential, and pure air and sunshine are important auxiliaries. A course of cod liver oil with bitters may be given to improve the general health, calcium sulphide may be tried in case of suppurative caries, and calcium phosphate will usually be desirable to improve the nutrition and consistency of the osseus system. In case of a valued patient which it is desirable to preserve for reasons of sentiment or affection, or for breeding purposes, one might be warranted in continuing a long and expensive course of treatment, but in the regular run of cases considerations of humanity and economy would counsel the prompt destruction of the animal.