Muscular and Skeletal Diseases

By | May 4, 2010

Arthritis
Disc Protrusion
Hip Dysplasia
Canine hip and Elbow Dysplasia
Scottie Cramp
Swimmer
Tetany
Fractures
Wobbler’s Syndrome, Surgical Success

Arthritis

Joint degeneration may be a result of deterioration with age, physical damage or infectious disease. Where changes occur in the cartilage which forms the articular part of the joint they are usually degenerative rather than inflammatory. Inflammatory changes occur with generalized infections or when one or two joints only are affected by an injury. The more inflammation the more pain with movement. Infection and injury, although more painful, may often result in eventual healing. With degenerative changes there is usually less inflammation, but more limitation of movement. Antibiotics are extensively used in the treatment of joint infections so as to prevent changes which will permanently incapacitate the dog. joint damage usually needs radiographic examination for a proper diagnosis and evaluation of the extent of damage. The commonest joints to show pathological changes are the stifle and the hip in the hindleg, and the shoulder and carpus in the foreleg.

Some hip problems can be resolved by completely excising the head of the femur where it sits in the hip socket; certain cases need an artificial hip joint, but others manage without any femoral head at all. All joint diseases, except for the mildest sprain, show symptoms of pain, swelling, local heat or restricted movement.

Hip Dysplasia

The hip is a relatively simple ball and socket joint, prone to inherited faulty development (dysplasia) in some breeds, resulting in various degrees of malfunction. The socket may be inadequate and too shallow for the head of the femur, the head of the femur may he misshapen, and bony outgrowths can develop round the joint itself.

Radiography is needed to assess the degree of dysplasia, but the extent of the damage to the joint may he quite disproportionate to the clinical picture. Dogs with apparently only slightly misshapen hip joints may be severely lame and in a good deal of pain. Others with extensive pathological changes may be sound for most of the time and be in no pain at all. Vigorous efforts are being made to reduce the incidence of inherited hip dysplasia, which is most prevalent in large breeds, particularly the German Shepherd Dog. Potential owners should always seek puppies from stock known to be sound. The English Kennel Club maintains a register of hip dysplasia score .

Various surgical procedures are used to alleviate the condition. They include removal of the femoral head and the use of artificial hip joints.

Causes of Hip Dysplasia

There are many theories regarding the cause of hip dysplasia and, from what one reads and hears it seems as if not too much is known about the cause. Some authorities claim that it is hereditary and polygenetic. Others claim that it is not congenital, but that it occurs during the later growth of the puppy, and that it may occur as late as its second year. It is surprising to find, along with many other defects, that hip dysplasia has been known in man for several thousand years. It is found in many animals, including horses, cattle and even in cats. It was first noticed in dogs in 1935. A great many breeds are affected, but it does seem to occur more frequently in the large, heavy puppies. The hip joint is a ball and socket joint, which simply means that the top of the thigh bone, or head of the femur, which should be round, fits into the deep socket of the pelvis, formed by the junction of the three pelvic bones. The bones normally fit each other perfectly, forming a stable ball-and-socket joint. But with hip dysplasia, instead of the femoral head being round, it loses its shape and becomes narrower, and the depth and shape of the socket are imperfect.

The bone no longer fits the socket snugly, and the socket in turn loses its shape and becomes too shallow. The strong ligaments which normally keep the ball-and-socket joint together do not work sufficiently well under the strain, and the malformed bone of the femur head moves about in the flattened socket. In severe cases there is complete dislocation of the hip, which causes a great deal of pain, and the dog is completely crippled. There are, of course, varying degrees of hip dysplasia, and in many cases it cannot be detected, except by X-ray, before the dog is a year old; but to be absolutely certain the dog should be at least two-year old. Dogs afflicted not too severely learn to compensate by developing and using particular muscles, and many dogs suffer no pain at all; but most dogs with even slight dysplasia tend to develop arthritis in old age. One of the worst afflicted breeds at the present time is the Alsation (German Shepherd Dog). It is worth watching the hind movement of Alsatians, since the dislocation of the hips is clearly visible in many of them.

Over Angulation of the Hind Limb

The normal dog has correct angulation of the joints in the hind limbs. Fashion unfortunately has decreed in some breeds a decided over-angulation of the joints. Over the years, in order to achieve this, certain changes have had to take place in the length of the main bones. The tibia has increased in length and the distance between the hock and the ground has become shorter. In the normal dog, the leg from the hock joint to the ground is inclined very slightly forward, whereas in most show breeds it is considered correct for the leg from the hock to the ground to be perpendicular. A serious fault is a sickle hock, which angles backwards. The diagrams of the hind limbs demonstrates what is known in show report terminology as a good turn of stifle. The angle at the rear of the stifle joint has been bred to become very much smaller than that found in the normal dog; the tibia, or lower thigh bone has become longer; and the leg from the hock to the ground has been made perpendicular. A serious fault is a sickle hock, which angles backwards. The diagram of the hind limbs demonstrates what is known in show report terminology as a good turn of stifle. The angle in the normal dog; the tibia, or lower thigh bone has become longer; and the leg from the hock to the ground has been made perpendicular. These skeletal changes of excessive angulation may possibly be a contributary cause of the pressure that now falls on the hip joint, where so much trouble is found. Perhaps for a period judges might refrain from putting up dogs with over-angulated hind limbs and not enthuse on beautiful turn of stifle, and slowly the breeds affected might return to the shape that nature intended.

Stifle Dysplasia

Stifle dysplasia, patella luxation, or slipping stifles as it is often referred to amongst dog people, is unfortunately far too common in a great many breeds. A slipped stifle is the dislocation of the patella, which is the equivalent of the dislocation of the knee cap in man. There are varying degrees of the abnormality. It seldom shows before the age of six months and may not show in the case of some bitches until after she has whelped her second litter. Dogs may develop partial dislocation in their old age. Obviously, the younger a dog is when partial or complete dislocation occurs, the worse it is for the dog, particularly when it occurs at about four to six months of age and evelops until about ten to twelve months of age. The patella is a small bone which lies in a shallow groove at the lower end of the thigh bones. Normally, when the dogs bends his knee the little bone moves along the shallow groove and is kept in place by the small ridges on either side of it, with the assitance of the ligaments. If the groove happens to be too shallow or the ridges too low, the knee cap slips out of the groove. The dog then ‘carries’ the affected leg and will run on three legs. It is more common for the patella to slip inwards from the mid-line.

There are at least six causes of styfle dysplasia. These are varied, and the majority are probably hereditary. Partial dislocation is what is most often observed in the ring in some breeds. The patella bone slides in and out of the trochlea depression on the femur with each step that the dog takes. When the dog is trotting, he may move astonishingly soundly. It is only when he is expected to stand that the slipping stifle may become obvious, since the joint becomes quite straight and, in order to compensate for this, the nearby joints are also affected. If the handler moves the dog slightly, the patella will return to the normal correct position. The more often that the patella slips out of the groove, the more strain is put on the surrounding ligaments and muscles. These become stretched and the general weakness at the joint increases.

If the dislocation becomes complete the patella over-rides the groove and the joint may lock. This is extremely painful, and if it occurs frequently an operation may be necessary. When the patella is locked, it slides over the outer edge of the trochlea groove, which acts rather like a pulley. The judge can feel the joint if it is grasped gently in the crooked fingers of the hand. The leg will often go straight and the joint above the foot becomes over-flexed. There is the tell-tale click, which can be heard quite distinctly in small breeds when the dog is picked up. Sometimes, a dog will perhaps be moving in the ring quite perfectly, when suddently he will give a little skip and hop along on three legs. The moment the patella returns to its correct position in the groove the dog continues to move soundly.

Judges may have gone over a dog throughly, seen him move correctly and with alcrity and, just as the dog is about to be awarded a first prize, he may stand for just a fleeting second with his hindleg in such a position that the judge knows that he has a slipping stifle. In breeds where the fault is rife, it is never fair for a judge to put a dog in a lower place because he has seen the dog previously and already knows his weakness. If the judge does not actually see the stifle go out at that show on that day, he has every right to put the dog up, provided he is the better dog. The judge may decide to play safe and put another dog up whose stifles looked stronger, but he may in fact be just as weak in stifle as the first dog. It is up to handlers to show their dog without allowing the fault to betray him.

Extremely active small breeds seem particularly prone to patella luxation.

Scottie Cramp

Cramp occurs in dogs such as racing Greyhounds because of muscle fatigue, but a different condition seems to be peculiar to Scottish Terriers. It shows as a stiffening of the legs, usually the forelimbs; the condition appears to be inherited, but affects only young dogs, mainly under eighteen months old. As the dog ages, Scottie Cramp disappears and with patience the situation will resolve itself. Breeding from affected individuals is inadvisable. Treatment to alleviate the symptoms may be needed if the dog is unable to walk.

Swimmers

This curious condition is seen in some puppies about one to two weeks old. They are unable to walk properly but ‘swim’ around on their undersides, propelled by limbs held in a near-horizontal plane. The condition may affect any breed, but a particularly severe form involving irreversible brain damage has been observed in Irish Setters. A similar condition, found in some Labrador litters, appears to be more like uncoordinated growth, with the body growing too rapidly for the legs to support it adequately. If the puppies continue to feed, relieve themselves and do not sustain any injuries, they usually recover.

Tetany

Tetanus infection, causing tetany in dogs and other mammals, is relatively rare in dogs. The organism involved, Clostridium tetani, normally lives in the gut of many species, particularly horses, and its presence is widespread in the soil. Farm dogs are the most likely to be exposed to Tetanus infection. The organism may proliferate in deep wounds or where oxygen is in short supply. Puncture wounds are the commonest route of entry for the organism, which produces a toxin causing the animal to go into rigid spasms. Although an affected dog does not usually eat, it does not seem to be affected with ‘lockjaw’, though the pull on the muscles round the head can give the appearance of a sardonic grin (risus sardonzicus).

Death may follow if the muscles controlling respiration are in continuous spasm. Vigorous therapy can be successful if begun in time.

Fractures

Any bone in the body can be broken, but if the animal is healthy quite strong forces are usually involved in fractures. Bones lacking mineral deposit may break spontaneously, or with very little outside influence Such conditions most frequently in dogs fed on muscle meat alone. Fractures of the limbs are a common result of traffic accidents and similar trauma. The forelimb may break in the mid humerus, at the point of the elbow, bottom of the radius and ulna just above the carpus. The hindlimb is often broken at the lower end of the femur; the smaller the end fragment, the more difficult is healing of the fracture. The head of the femur may be snapped off, resulting in considerable pain. The tibia below the knee joint and the point of the hock are other common sites. The pelvis is often broken in traffic accidents, but, like the jaw, usually heals surprisingly well.

Less promising are fractures of the spine as the spinal cord is likely to suffer irreparable damage; paralysis is a common result, although the bone may well heal. Modern techniques of pinning and plating, as well as long-established standing methods such as plastering, can deal with most fractured bones.

Wobbler’s Syndrome, Surgical Success

The onset of Wobbler’s disease is usually slow and insidious. Probably the first sign to come to an owner’s attention is an asymmetrical gait in the hind legs. Similar faulty movement will follow in the forequarters. Although eventually the dog will both move and stand “wide” the feet may cross when rounding a turn. Swaying will develop in the hindquarters, lending the disease its name. The dog’s nails may click on stairs, as it misjudges the height of the stops. It may lower its head and extend its neck, relieving pressure on the spine.

Yet, with all this, it does not appear to be suffering much pain. J. L. Tomlinson, DVM, University of Missouri College of Veterinary Medicine, is perfecting surgery to correct the form of Wobbler’s disease resulting from enlarged ligaments. This has come to the fore particularly in Doberman Pinschers although other large breeds may be affected and is primarily a problem of middle age. An other form, caused by bone deformity, is seen all too often in young Great Danes. “Sometimes an owner will claim to have seen no signs; the dog will just go down suddenly, unable to walk,” Dr. Tomlinson comments. “But in most cases, there’s a six-to- nine month progression. Often the symptoms are taken for those of hip dysplasia”. Original work on the technique was performed at Colorado State. Dr. Tomlinson has been interested in it for over three years. At the time of our interview, he had performed ten operations on Wobbler’s sufferers, and two more dogs were waiting in the wings. His first Doberman patient was an 11-year-old male which could take only a couple of steps before failing over. His ovvners felt they had to put him to sleep. After the surgery, he was so weak we had to put him in one of our walking carts. After a month, he could walk vvithout it. Two years later, Shadow is still doing well so you see, we can take on really severe cases.
In this form, generally only one disc is involved. The operation attempts to fuse the vertebrae on either side of the disc in linear extension, to relieve the pressure placed on the spinal cord by an enlarged ligament. Holes are drilled in the vertebrae, pieces of cortical (dense) bone are inserted, and the cavities packed with cancellous (spongy) bone. A plastic spinal plate may be inserted. As the patient grows new bone two vertebrae become fused together. This procedure has not been carried out long enough, of course, to determine whether or not the problem will reccur at the same or a different location over the long range. So far, the success rate has been better than 80% if the dog could walk before surgery; about 50%, if it was unable to get around. “Recovery time depends largely on the severity of the neurological damage,” according to Dr. Tomlinson. “The dog is placed in a body cast .for about three months, and must be fed and watered from an elevated position.

Usually by the end of a month the dog is dramatically improved, and at the end of three the owners think it’s normal except for being a little clumsy as a result of the cast.”Most patients returning for their six-month checkup reveal no neurological deficits. When Wobbler’s disease is caused by bony deformity, the bone extends into the spinal canal, often over the space of more than one disc, bringing pressure on the ligaments which then impact the spine. If surgical correction were possible, it would be far more radical. Dr.Tomlinson emphasizes that a myelogram is essential to establish the existence of Wobbler’s disease. At the same time, the special radiograph, enhanced by injection of a contrast dye, pinpoints the exact location of the problem. Traction views are most important; if pressure on the spinal cord can be thus relieved, the surgery is very likely to be of benefit. There are other surgical advances underway at Missouri. One involves a synthetic Dacron-ligament material of double-knit velour, woven in a double H-beam configuration. Within the patient the strong fabric provides a matrix into which fibrous tissue grows resulting in both strength and flexibility. The Dacron is non-reactive, and possesses a very high modulus of elasticity. Shoulders, hips, knees-virtually every joint in the body is a candidate for possible use. “The only present drawback for veterinary use is cost about 3/cm”. Dr. Tomlinson says. “On the other hand, surgical time is much shorter than that required for body grafts. This reduces operating cost, and also the danger to the patient from long periods under anesthesia”. Stryker Corp., marketer of this product, has donated approximately 1350 worth of the material to Missouri, and some individual clients also are helping fund this research, Traditional superglues, which break down into formalin and other toxic substances, obviously are unsuitable for surgical, repairs. Now a material from Japan “Aron Alpha,” shows Promise for a wide range of applications, Approved for human use(Iimited to emergencies) the product is iso butylcyanoacrylite – which breaks down slowly enough for the body to accommodate it, and so far shows no signs of being toxic. This “glue”, Dr. Tomlinson explains,. while not strong enough to be used alone, will secure important fragments in place which are too small for wiring. As the body’s own bone is utilized, it assimilates better for faster healing of the fracture. Sill in the research stages, the material should be ready for trial on clinic patients, within a year. The American Kennel Club has been supporting this work. Successes in both areas could have important ramifications in human-as well as ,veterinary-medicine, Dr. Tomlinson point out.

Nutrition a factor

Pups of the larger breeds are encouraged to grow too fast, Dr. Tomlinson is convinced. Many of the problems referred to him,’ such as osteochondrosis stimulated by over- supplementation with calories, protein, calcium and phosphorus. And when this is coupled with genetic predisposition, “the dogs grow monstrous.” Often the well-meaning owners are simply following the advice of breeders or their personal veterinarians. “I had one five-month old Great Dane which already weighed close to 130 lb. and could hardly walk,” he says.”In my opinion, show enthusiasts want members of giant breeds as big as possible. This leads to the largest being chosen as most desirable for breeding. To really get to the roots of this problem would be a very expensive long-term project. It would need to involve a lot of dogs, plus people from various disciplines-nutrionists and breeders, as well as veterinarians. “Nutrition is far more irnportant than is generally recognized in human or veterinary medicine.” He recommends keeping dogs lean.