Arthritis Due to Autoimmune Disease

Sometimes, an overactive immune system can lead to an arthritic condition. In these instances, immune complexes consisting of antibodies coalesce within the joints of the body, causing inflammation. The resultant polyarthritis can be very painful and debilitating. Fever and a generalized depression are also features of these diseases.

Dogs can get rheumatoid arthritis just as people can. In dogs, this autoimmunity-related disease is seen more frequently in the toy breeds than in any others. Another autoimmune disease in dogs that can cause arthritis is called systemic lupus. In contrast to rheumatoid arthritis, systemic lupus usually favors the larger breeds of dog, such as German shepherds and St. Bernards.

Many cats that suffer from immunity-related polyarthritis are also infected with the feline leukemia virus. As a result, other symptoms not related to the arthritis might be seen. Fever and a generalized depression are two of these that are seen quite consistently.

Special blood tests and/or tests on joint fluid are used to diagnose autoimmune disorders in pets. Treatment usually consists of high dosages of steroid anti-inflammatory medications designed to curb the body’s overactive immune response.

Hip Dysplasia

Hip dysplasia refers to an inherited arthritic condition involving one or both hip joints of affected dogs. It presents itself as a partial dislocation, or in severe cases, a complete dislocation of the hip joints.

With time, the cartilage lining the joint surfaces wears down as a result of the abnormal stress and strain placed on the joint, and arthritis results. Although hip dysplasia can be a problem in any breed, it is seen most often in larger purebred dogs, such as German shepherds, golden retrievers, Labrador retrievers, and St. Bernards. In German shepherds alone, the incidence is thought to be as high as 80 percent!

Because of its inherited nature, signs associated with hip dysplasia may appear as early as 4 weeks of age, although as a rule, most cases show up around 8 to 12 months of age. These clinical signs consist of posterior pain, unsteadiness on the hind limbs, difficulty in rising from a prone position, and a reluctance to move or exercise. Manipulation of the hip joints will reveal obvious pain. In less severe cases, signs might appear only after intense activity and exercise.

Diagnosis of hip dysplasia is achieved by radiographing (X raying) suspected joints and from a history of this disorder in the dog’s genetic bloodline. Several registries aimed at controlling genetic diseases in dogs have developed guidelines and testing procedures for veterinarians in an effort to detect this disease in puppies and young dogs before clinical signs even appear.

In otherwise healthy dogs exhibiting marked lameness due to dysplasia, a number of different surgical techniques can be employed to help relieve pain and lameness caused by the disease, and/or to actually reconstruct the hip joint(s). Total hip joint replacements using prosthetic devices can be performed as well in certain cases to afford a permanent cure. As a rule, the smaller the dog involved, the better the results achieved through surgical intervention.

In dogs that are poor surgical candidates, anti-inflammatory medications can be used to temporarily decrease pain and discomfort associated with hip dysplasia. A program of regular exercise and weight loss can also benefit these patients. Also, disease-modifying osteoarthritis drugs (DMOADs) such as the polysulfated glycosaminoglycans, glucosamine, chondroitin sulfate, and hyaluronic acid have been used with great success to stimulate repair of damaged cartilage within diseased joints, instead of just masking the pain caused by the arthritis.

Osteochondrosis

Osteochondrosis describes a condition characterized by abnormal development and growth of joint cartilage. It is seen in young dogs and usually strikes larger breeds. Thought to be caused by trauma and overfeeding, osteochondrosis can precipitate painful joint inflammation and lameness in these pets. The shoulder, elbow, knee, and hock joints are the regions most commonly affected.

Radiographic X rays are used to definitively diagnose osteochondrosis in a dog. In many of these dogs, healing will occur spontaneously over 4 to 6 weeks with strict cage rest. If the cartilage defect is extensive, or if pieces of cartilage have broken off and are floating freely within the joint, surgical intervention might be necessary to remove any dead cartilage and to stimulate healing. Anti-inflammatory medications can be used to temporarily decrease pain and discomfort associated with this condition. Disease-modifying osteoarthritis drugs such as the polysulfated glycosaminoglycans, glucosamine, chondroitin sulfate, and hyaluronic acid can be employed in the conservative treatment of osteochondrosis in dogs. As in hip dysplasia, these agents appear to satisfactorily set the stage for healing to take place within the defective cartilage.

Legg-Perthes Disease

Legg-Perthes disease, or ischemic femoral head necrosis, is an orthopedic condition involving the hips of smaller breeds of dogs, such as Yorkshire terriers and miniature poodles. This condition is characterized by a degeneration of the head of the femur bone—that portion which fits into the socket of the pelvis to form the hip joint.

Hereditary in nature, Legg-Perthes disease usually appears around 3 to 9 months of age. Clinical signs associated with this disease include lameness and painful hips. On radiographic diagnosis, treatment for Legg-Perthes disease involves surgical removal of the head of the affected femur(s). Most dogs, because of their light weight, can return to normal locomotion and activity within a matter of days to weeks after such a surgery.

Patellar Luxation (Dogs)

Patellar luxation is an orthopedic condition in which the patella, or kneecap, “slips” to one side of the knee joint, causing pain and loss of the joint function. Medial patellar luxation, in which the patella slips to the inside surface of the joint, is most often seen in the toy breeds, such as Yorkshire terriers, poodles, and Pomeranians.

Lateral patellar luxation, where the kneecap migrates to the outer surface of theknee joint, shows no true breed disposition, with larger dogs sometimes affected. Regardless of the type, patellar luxation can occur secondary to direct trauma to the joint, or can be caused by an abnormal anatomic development of the bones comprising the knee joint.

Signs of this problem can occur as early as 6 months of age in affected dogs. Milder cases often go unnoticed for years until arthritis of the affected knee sets in. Symptoms associated with patellar luxation include intermittent lameness, with the dog often reluctant to put the affected hind leg on the ground. Dogs affected with this problem might seem fine one minute, and then suddenly let out a yelp and come up overtly lame. Many times, the patella will slip back into place by itself and the dog will seem fine again. However, if this condition continues for a long time, arthritis of the knee joint eventually occurs, and the lameness signs will fail to disappear. An easily displaced patella found on physical examination will confirm a diagnosis of patellar luxation. Radiographs are helpful as well to determine the extent of arthritis involvement, if any at all.

Surgical correction of patellar luxation is the treatment of choice in these pets. This involves altering the anatomy of the tibia (the shin-bone that makes up the lower portion of the knee joint) in such a way that the patella is not allowed to slip to either side. The prognosis after surgery is good to excellent for complete remission of signs. In those dogs that have problems with both knee joints, surgical repair of both legs may be necessary.

Torn Knee Ligaments (Cruciate Injuries)

The knee joints of dogs and cats (and of people) are held together by a fibrous joint capsule and a number of ligaments; the most prominent of these are the cruciate ligaments. Because of their configuration, the range of motion allowed the knee joint is limited to simple flexion and extension. If an abnormal force is placed on the joint from trauma or from planting the leg wrong on the ground, these ligaments could tear or rupture, leading to instability and pain within the affected knee joint. This instability, if not corrected in a timely fashion, will lead to arthritic changes and permanent pain within the joint .

As with humans, cruciate injuries seemingly affect active, athletic canines more than others do, but older, obese dogs and cats also have their fair share of this type of problem. Ruptured cruciates can also occur secondary to patellar luxation in toy dog breeds. Acute ruptures or tears involving the cruciate ligaments usually result in a sudden, non-weight-bearing lameness in pets so affected. Over time, a gradual return to function can occur even if the condition is not treated, but the lameness will undoubtedly return as the activity level of the pet increases or as arthritis strikes the joint.

A diagnosis of torn knee ligaments is made if a veterinarian can demonstrate an obvious laxity within the affected knee joint. Because of the pain involved with such a diagnostic procedure, sedation might be necessary in order to obtain an accurate assessment. Radiographs might be helpful, depending on the duration of the problem.

Treatment of this condition involves surgical repair and reconstruction of the torn ligaments in an effort to restore normal knee joint stability. Many techniques for such repair are available for use, depending on the extent of the injury and other circumstances involved. In general, cats and smaller dogs that do not have to carry as much weight around on their knee joints as do larger dogs have the most satisfactory postsurgical results. Following surgical repair, disease-modifying osteoarthritis drugs (DMOADs) can be used to speed the healing of any cartilage damaged as a result of the injury.

Hip Luxation

One common sequela to car accidents and other types of trauma involving dogs and cats is dislocation, or luxation, of one or both hip joints. These pets usually have a non-weight-bearing lameness on the affected leg, and it is quite painful. Diagnosis can be made with a physical examination and radiographic X rays of the hips and pelvis.

Treatment usually involves surgical stabilization of the hip joint to restore function and to prevent recurrence. In cats and small dogs, the head of the femur may actually be removed to allow a false joint to form at the site.

Fractures

Most bone fractures in dogs and cats are trauma-related. In isolated instances, metabolic diseases, such as nutritional osteodystrophy and bone cancers, can also be underlying causes. A fracture will present itself as a non-weight-bearing lameness, with noticeable swelling and pain in the region of the affected bone. Crepitus, or the grinding feel made by broken ends of bone rubbing together, and an anatomical distortion of the site, such as a shortening of an affected limb, might be seen as well.

Diagnosis of a fracture is based on physical exam findings and radiographic X rays. Treatment depends on the type of fracture and the region involved, and it consists of any combination of cage rest, bandaging or splinting, and surgery to reduce and stabilize the fracture. Minor fractures involving the pelvis will often heal nicely with cage rest alone, whereas displaced fractures of one or more limbs might require surgical fixation using orthopedic pins, screws, and/or bone plates. In general, uncomplicated fractures usually heal quite readily in dogs and cats.

Osteomyelitis

Infections involving bony tissue within the body are termed osteomyelitis. Bacterial osteomyelitis in dogs and cats can occur secondary to a deep bite wound or some other type of penetrating trauma.

Open fractures can also predispose to bone infections. Furthermore, fungal organisms, such as histoplasmosis and blastomycosis, can also spread from other areas of the body via the blood and infect bony tissue in pets. Dogs and cats with osteomyelitis are lame and feverish, and usually feel considerable pain at the affected site. These signs, combined with the localized swelling that often occurs, can easily be mistaken for a fracture and must be differentiated from one. To do this, radiographic X rays should be taken of the suspected skeletal region. In addition, bone biopsies might be necessary to differentiate some cases of osteomyelitis from bone tumors, and to collect samples for bacterial or fungal cultures.

Because infections that become embedded in bone can be difficult to clear up with antibiotics alone, surgery is usually needed to actually remove those portions of bone severely affected. Drain tubes are placed as well to allow for postsurgical drainage and flushing of the site with medicated solutions. Following surgery, antibiotic therapy might be required for 1 to 2 months. If a fungal organism is involved, medications might need to be given for 4 to 6 months.

Spondylosis Deformans (Dogs)

Spondylosis deformans is a degenerative bone condition that seems to be related to the aging process in some dogs, especially the larger breeds. It is characterized by the development of bony spurs that originate from intervertebral disks and grow to bridge the gap between adjacent vertebrae. These spurs are evident on radiographic X rays. Most dogs afflicted with this disorder show no clinical signs whatsoever. However, in some dogs, pressure and pain originating from these bony growths can cause prominent hind-end weakness and reluctance to move.

Unfortunately, there is no cure for spondylosis deformans. Discomfort associated with the condition can be temporarily relieved with anti-inflammatory medication.

Metabolic Bone Disease

Metabolic bone diseases are characterized by a thinning and loss of bony mass, predisposing the bone to fractures and growth deformities. The most common metabolic bone disease seen in dogs and cats is hyperparathyroidism. This condition is characterized by a calcium deficiency within the body that leads to abnormal bone growth and bone resorption as the body tries to correct the low calcium levels in the bloodstream. Hyperparathyroidism can result from feeding pets all-meat diets (which are naturally low in calcium), or it can result secondary to kidney disease.

Dogs and cats afflicted with metabolic bone diseases exhibit lameness, weakness, bone and joint deformities, and spontaneous fractures. Diagnosis is based on radiographic X-ray findings and on blood calcium measurements. Treatment for nutritionally related bone disease obviously involves changes in the diet and calcium supplementation. Treatment for kidney-related hyperparathyroidism is geared toward counteracting the kidney disease itself.

Another type of metabolic bone disease that can affect cats is called hypervitaminosis A. This condition is seen in those cats fed an exclusive diet of liver, which contain high levels of vitamin A. Musculoskeletal changes seen in cats experiencing chronic vitamin A toxicity include bony deformities, outgrowths, and fusion involving the vertebral column, especially in the region of the neck, and bony fusion of the joints of the limbs, resulting in pain and immobility.

A history of an all-liver diet, combined with clinical signs and radiographic analysis of the spine and limbs, can reveal conclusive evidence of hypervitaminosis A. If detected early in its development, this condition can often be reversed by switching the cat to a balanced diet. However, in advanced cases, the bony changes that occur are usually permanent, and anti-inflammatory medications are usually required for the remaining life of the cat to help ease the pain associated with the disease.

Mucopolysaccharidosis (Cats)

Mucopolysaccharidosis is an inherited disorder that has been documented in Siamese cats. It results from an enzyme deficiency that allows polysaccharide carbohydrates to accumulate within the cells of the body.

The skeletal system is particularly affected, with stricken cats suffering from bony spurs on the vertebrae, arthritis and abnormal formation of the joints, and a generalized osteoporosis, or thinning of the bones themselves. These cats also have a characteristic “flattening” of the face, resulting from a widening of the facial structure, and, at an early age, can suffer from opacities or cloudiness involving the corneas of both eyes.

Diagnosis of mucopolysaccharidosis is made by physical examination, blood tests, and radiographic X rays of the skeletal system. A special test that detects mucopolysaccharides in the urine can also be employed in diagnosing this disorder. Unfortunately, because of the inherited nature of this disease, there is no known treatment. Future generations should be protected by neutering those pets affected to prevent passage of the trait.

Myositis and Myopathies

Myositis is inflammation of muscle tissue that results in pain, weakness, and muscle atrophy (shrinking). Dogs and cats suffering from severe bouts of myositis are reluctant to move and can actually appear as if they are paralyzed as a result of the inflammatory effects on the muscles. Myositis can be caused by a number of different disease entities, including toxoplasmosis, leptospirosis, bacterial infections (abscesses), low blood potassium (see text below), and autoimmune disease. One special type of myositis, called masticatory myositis, affects the facial muscles of affected dogs, causing atrophy and the inability to chew normally. This autoimmune disease is seen most frequently in German shepherds.

Myositis is diagnosed using clinical signs and blood tests designed to detect increased levels in muscle enzymes within the blood. In especially elusive cases, biopsy samples taken from suspected muscle tissue can help veterinarians obtain a definitive diagnosis.

Treatment for myositis is aimed at the underlying cause. If infections are to blame, appropriate antimicrobial or antiparasitic therapy will help relieve the myositis. Anti-inflammatory medications can also be used to relieve the pain and discomfort associated with the inflammation until the underlying cause is treated.

Autoimmune myositis, such as masticatory myositis, is treated with high levels of glucocorticosteroids (such as prednisolone) in an effort to suppress the immune response causing the inflammation in the first place. The prognosis for complete recovery with autoimmune myositis is poor, yet with medications, the signs associated with the disorder can be kept under control.

The term myopathy refers to abnormal anatomy and/or function of skeletal muscle tissue within the body. Most myopathies in dogs are inherited. Chow chows, golden retrievers, and Irish terriers are examples of breeds that can suffer from inherited myopathies. Dogs suffering from myopathies exhibit abnormal postures, stiff gaits, and generalized shrinking or atrophy of the muscles. Because of the inherited nature of these diseases, the onset of clinical signs usually occurs within a year of age. Unfortunately, there is no effective treatment to stop the progression of these myopathies.

Hypokalemic Myopathy (Potassium Depletion) in Cats

As an electrolyte, potassium serves a variety of functions within the body, including maintaining proper fluid volume and pH. Potassium is also necessary for normal muscle contraction. Many illnesses in cats can also produce deficiencies in this electrolyte, or hypokalemia, within their bodies. This is especially true for those cats suffering from kidney disease, liver disease, or diabetes mellitus. Actual signs of hypokalemia can include weight loss, loss of appetite, constipation (due to poor motility of the muscles lining the gastrointestinal tract), muscle weakness, muscle pain, and incoordination. As the condition progresses and respiratory muscles become affected, breathing difficulties might be noted. In severe cases, death from respiratory paralysis could result.

Diagnosis of hypokalemia in a sick cat is based on a history, clinical signs, and measurements of blood potassium levels. If hypokalemia is diagnosed, treatment consists of intravenous injections of a potassium supplement to correct the immediate deficit, followed by oral supplementation as long as deemed necessary.

Prognosis for recovery is good if treatment begins early on.

Hernias

A hernia results from a tear or defect in a muscular wall, allowing the contents contained behind the wall to protrude through the opening in the muscle. In dogs, the four most prevalent types of hernias include umbilical hernias, inguinal hernias, perineal hernias, and diaphragmatic hernias. In cats, diaphragmatic hernias are the types most commonly seen.

Umbilical hernias occur on the midline of the dog’s stomach at the location of the umbilicus, or the belly button. These usually result from trauma to the muscle wall in this area that occurs when the bitch severs the umbilical cord after birth. Umbilical hernias pose no real health problems, since fatty tissue is usually the only item that ever protrudes through the opening. These hernias can be sutured and repaired at the time of other elective surgeries.

Inguinal hernias occur in the inguinal region of the abdomen, or that region where the abdominal musculature meets that of the hind legs. They are seen as birth defects or secondary to trauma. These hernias are more serious than umbilical hernias, since the herniated material often includes intestines. As a result, normal digestive processes can be disrupted. Treatment involves surgical replacement of the herniated material back inside the abdomen and suturing the defective muscle.

Perineal hernias result from a weakening of the musculature in the region located beneath the tail on either side of the anus. Seen primarily in older male dogs that have not been neutered, perineal hernias can involve portions of the colon and cause impactions and elimination problems if not surgically corrected. Because the hormone testosterone seems to play a role in the development of these hernias, neutering these dogs is also recommended to prevent a recurrence.

By far the most serious type of hernia is the diaphragmatic hernia. The diaphragm is the thick wall of muscle that separates the thorax or chest cavity from the abdominal contents. Tears or ruptures occurring in this band of muscle, resulting either from inherited defects or from traumatic incidents, can allow liver, intestines, and/or other abdominal contents to herniate into the chest cavity. When this happens, the pressure applied to the crowded lungs and heart results in, among other things, breathing difficulties, weakness, and/or gastrointestinal disturbances.

Definitive diagnosis of a diaphragmatic hernia can be made by coupling history, clinical signs, and a physical examination with radiographic X-ray findings. Surgical repair of the torn diaphragm will alleviate the signs and usually result in a complete recovery.

Vestibular Disease

The vestibular system is a specialized portion of the nervous system found within the inner ear, brain, and spinal cord. Its duty is to maintain a state of equilibrium and balance. By communicating with the nerves supplying the eyes, limbs, and trunk, the body is able to coordinate the position and activity of these regions with movements of the head.

Peripheral vestibular dysfunction (PVD) is a disease that affects the nerves of the vestibular apparatus in the ears. PVD is characterized by a sudden onset of incoordination and loss of balance, which is often accompanied by a head tilt, involuntary twitching of the eyeballs, and in many cases, vomiting. The causes of this disorder can include trauma to the ears, skull infections, and tumors involving the middle or inner ear. Diagnosis of PVD is achieved using clinical signs and various laboratory tests to rule out other potential causes of the symptoms. Radiographs of the skull may be helpful in the detection of any masses or infections that may involve the inner portions of the ears. Treatment, of course, depends on the underlying cause and usually includes high doses of corticosteroid medications designed to reduce inflammation involving the vestibular apparatus.

Vestibular ataxia syndrome is seen in kittens born of queens stricken with feline parvovirus during pregnancy. Owners often are alerted to a problem when these kittens seem to have trouble in attempting to walk. The condition will not improve as these kittens mature, nor will it usually worsen.

Congenital vestibular syndrome is seen in Siamese and Burmese cats, with signs appearing anywhere from 2 to 4 weeks of age. Many of the Siamese cats affected are deaf as well. The prognosis for Siamese

cats with congenital vestibular syndrome is good, with clinical signs usually abating by the time the cat is 6 months of age. In Burmese cats, however, the prognosis is not as good, and the poor quality of life for most of these individuals will usually warrant euthanasia.

Date: 2014-12-28; view: 1065