Canine Joint Health

By Randy Kidd, DVM, PhD Western medicine’s mechanistic theory regards the body’s joints simply as the anatomic sites where the lever action of bones enables body movement. However, joints are much more complex than this, anatomically, mechanistically, and functionally. And when disease exists within any joint, the result can be completely disabling – not only to the local area but also to the entire body. If we view joints as another of the body’s organ systems with a multitude of functions, we will have a better chance to see their importance in the holistic balance of the animal’s overall well-being.

For starters, it is important to appreciate that joints would have no function at all without their supporting cast of surrounding muscles, ligaments, tendons, nerves, shock absorbers (spinal discs and joint meniscuses), and lubricant-producing synovial membrane. Further, a joint’s functional surfaces are poorly supplied with blood and lymph vessels, and they are isolated from other tissues by means of a sturdy joint capsule – this lack of circulation and isolation makes healing of any disease process within joints much more difficult. A short list of some of the functions of joints (in addition to their mechanical function as motion-producing levers) includes: • Stability. Joint-stabilizing structures surrounding the joints include ligaments (fibrous tissues that join from bone to bone), tendons (fibrous cord-like extensions of muscles that attach the muscles to bones), and muscles. Dogs with a fit and healthy muscle mass surrounding the hips are best-protected against developing hip dysplasia. • Proprioception. The ligaments, tendons, and especially the small muscles surrounding the joints are rich in proprioceptive nerve endings – nerves that relay to the dog’s brain the position of all its body parts at any one time. Proprioceptive information is vital for body balance, especially when the dog is moving. • Lubrication. Synovial membranes (the inner lining of the joint capsule) produce a slippery substance that acts as lubrication so that joint surfaces can move freely against each other. • Shock absorption. Bone ends are composed of soft, cartilaginous tissue that acts as a shock absorber for moving and weight-bearing bones. In addition, some joints have additional padding – examples include the discs between the vertebrae of the spine and the meniscus of the knee (the knee’s meniscus is a crescent-shaped fibrocartilaginous pad located within the joint). The “shock” of lateral and rotational motions is held in check by the joint’s surrounding tissues: muscles, tendons, and ligaments. • Spring action. Tensions on ligaments and tendons create within the joint a spring-like action, in a mechanical fashion much like the tightening and loosening of a rubber band. In addition, the anatomical setup of the joint itself may be spring-like, offering protection during compression and extra oomph during its expansion phase. (Think of the hock here, with its amazing ability to compress down and then spring apart when the dog leaps.) • Whole-body flexibility. Joints are, of course, responsible for the body’s flexibility, but it is important that this flexibility is actively and persistently utilized through movement (exercise) and that it is maintained in balance. • Structural realignment. Joints are the primary sites for structural realignment of the skeleton’s supporting structure. Chronic trauma or excess structural pressures (from anatomically mal-aligned bones) start a process of inflammation and new bone growth, which ultimately creates an increased amount of bony tissue along the side of the joint that is responding to the pressure. This bone growth is often painful and may become so painful as to render the joint unusable. • Pain. Pain located in the region of the joint may become so severe the animal becomes reluctant to move, and as the joint becomes less and less active, it ultimately may produce enough compensatory bony tissue (exostosis) to completely fuse the area into an immovable joint. • Immune function. Scientists haven’t yet determined the exact extent of the immune function of an animal’s joints, but we do know that the joints can be severely affected when the immune system has gone amok – rheumatoid arthritis is our signifier here. It’s my guess that as we further evaluate the joints, we will discover their vital role in maintaining a healthy, whole-body immune system – joints are, after all, involved in every body movement (one of the factors that determines life itself), and they are in constant contact with some of the longest-lived tissues in the body (bone). Joint anatomy Simply defined, a joint is the site where two or more bones articulate with one another, creating a lever that results in motion of the corresponding body parts. There are many ways joints create this articulation, and various classifications of joints result from these differences. The most common classification corresponds to the structural geometry of the joint. This results in terms such as a “ball and socket” joint (such as the hip) and a “hinge” joint (such as the dog’s carpus, similar to the human wrist). Hinge joints typically move like a door hinge, in one line of direction only. A true ball and socket joint would be able to move in all directions: forward, backward, laterally, medially, and rotationally. However, some ball and socket joints are limited in their totality of movement somewhat by the structures surrounding the joint. Surrounding structures Many (but not all) joints are surrounded by a thick and fibrous capsule, which effectively protects the inner workings of the joint and creates a barrier to injury and infections. The joint capsule’s inner lining, the synovial membrane, produces a thick, gelatinous fluid that acts as lubrication for the joint. Most of the nutrients needed for the joint and cartilaginous tissues at the ends of bones come from the synovial fluids – an important consideration since cartilage and the joint surfaces are poorly supplied by blood vessels. Synovial tissues react to trauma and invading infections; the result is an increased thickness of tissue along with increased production of the components of inflammation. This inflammatory synovial reaction can be assessed via needle biopsy. Tendons are fibrous extensions of muscles that attach the muscle to bone; when the muscle contracts, it moves its attached bone across the “lever” of the joint. Ligaments are attached across the joint, bone to bone; their primary function is to stabilize the joint. Both ligaments and tendons are sturdy structures that, when they are healthy, have enough strength (almost as much as bone itself) to withstand many times the forces that a joint would normally be exposed to. Ligaments and tendons are primarily composed of fibrous and cartilaginous tissues, but both also contain some elastic tissue to allow for a certain amount of stretching. Fascia is a fibrous connective tissue that surrounds tendons and ligaments, dividing larger muscle masses into smaller muscle “bellies.” Fascia also protects blood vessels as they course through the muscles. In fact, the contraction and relaxation of the blanket of fascia surrounding blood vessels acts as a secondary blood pump that enhances blood flow through tendons and into joints whenever the dog is active – yet another reason to make sure your dog gets enough exercise. Muscles that surround the joint are also an important component of stability and proprioception. The more fit the muscles, the more stable the joint. There is some evidence that exercise helps develop proprioceptive nerve centers in the smaller muscles around joints, thus providing fit individuals with a better sense of balance. Joint function Proper functioning of the joint depends on several factors, including: • Anatomy that creates proper alignment of the joint surfaces – skeletal alignment that allows the joints to move in the direction(s) they were meant to move in • Surrounding tissues that provide flexibility as well as stability • Articulating surfaces that are relatively smooth and that are lubricated for ease of motion • A functioning proprioceptive nervous system that connects the joints to the brain and that relays an accurate positioning of the body parts involved • A balanced, whole-body immune system that can maintain an immune response to fend off minor infections or injuries AND can do so without creating an overactive immune response (as seen with rheumatoid arthritis, for example). Joints and joint surfaces There have been a lot of recent studies on the physiology of joints, probably because we now recognize that they are a prime site of disease in both dogs and humans. Nearly 70 million people suffer from arthritis or some form of chronic joint pain, and joint conditions – especially chronic conditions – may be the number one disease entity seen by holistic veterinarians. When joint physiology is good, the smooth surfaces where the bones come into contact with each other articulate with ease and their weight-bearing forces are cushioned on impact. The functional health of joints is achieved by a balance of cartilage regeneration and degeneration, coupled with an adequate production of lubricating substances. The cartilaginous ends of bones are mostly water (some 65 to 80 percent of the total matrix), with most of the balance of the matrix being a mixture of collagen and proteoglycans. Within the mix are a small number of chondrocytes, the cells responsible for repair and regulation of cartilage tissues. Collagen is a primary connective tissue that exists in various forms and performs many different functions. It acts like an adhesive or glue-like substance throughout the body, helps maintain structure, and in cartilage, provides a framework to hold the proteoglycans in place as well as providing elasticity and shock absorbency. Proteoglycans are complex molecules composed of sugars and proteins. They interlink with collagen fibers, helping to make the cartilage resilient so it can stretch and spring back into place. Proteoglycans also trap water, acting like a sponge, which gives cartilage the flexibility needed for the constant motion of the joint. Proteoglycans link to core proteins to form glycosaminoglycans (GAGs), which are important components used for joint healing. Any excess demand – in the form of wear and tear, or as a result of infection-induced and/or immune-mediated degenerative processes – can be cause for erosion of the bone’s cartilage. Once again, we have created the most common reason for excess wear and tear of the joints; dogs with skeletal structures that are unnatural for the species are certain to be more susceptible to abnormal wear and tear of their joints. Excess joint erosion precipitates an inflammatory response, resulting in synovial membrane thickening and the release of white blood cells and other products of inflammation. As the erosion of the cartilage proceeds, the joint surface becomes rough and eventually the animal may begin to experience pain. Further erosion may remove the protective layer of cartilage, leaving bone to rub against bone. The body’s healing mechanisms interpret bone against bone as excess structural stress, and the body responds by producing more bone to counter the stress. This “new” bone often forms as disorganized clumps of bony tissue (exostoses) surrounding the joint, and these bony proliferations cause more pain (and more inflammation) as tender tissues rub against them. Without something to halt the process, it becomes ongoing, chronic, and progressively worse. Repair of damaged joint tissue can begin after the inciting cause has been eliminated or removed. Then, the few chondrocytes located in the bone ends can begin to (slowly) add new cartilaginous tissue. The key component to the synthesis of new cartilaginous tissue is the production of glycosaminoglycans (GAGs), for which glucosamine is the basic building block. Tendons and ligaments Tendons are the cord-like extensions of muscles that attach muscles to bones. It is through this attachment that the tendons move adjacent bones. This levering action depends on the tendon’s ability to slip and slide – an ability made possible by a slippery-surfaced sheath that surrounds the tendon. The tendon sheath is kept functional by a constantly balanced process of new tissue growth and tissue degradation, with the new tissues always being aligned with the tendon’s need to be slippery. Here’s the rub: If a tendon is severely damaged, the body tries to repair it by forming a scar, and the scar’s only purpose is to reunite damaged ends of the tear. As the torn tendon heals, the scar will likely fuse the ends without returning the normally slippery function of the tendon. There are several surgical methods to help maintain normal tendon function, but the caveat is that the surgical attempts must be done immediately (within hours) and that the surgeon be proficient in joint repair. The need for super precise joint movements is generally not so great in dogs as it is in humans (especially in human fingers), and adequate function can usually be retained after “normal” surgical procedures. Tendon repair takes about six weeks. During the first three weeks the opposing ends of the tendon need to be kept immobile; during the next three weeks the tendon needs to have some movement (through less vigorous external splinting) to allow for remodeling that will (we hope) include the addition of a tendon sheath to provide for slippage. Complete healing may take more than a year, and the completely healed tendon will likely be only 90 percent as strong as it was originally.

Ligament healing is not predictable; some heal, seemingly spontaneously; others are almost impossible to repair, even with the best of surgical techniques. For these problem ligaments, techniques have been developed to use transplanted fibrous tissues to repair the damage. Another potential problem arises when bone fragments or particles of cartilage flake off from areas of joint inflammation, and they become abrasive “floaters” that add to a joint’s pain and inflammatory process. Usually, the only cure for these floaters is to have them surgically removed. Whenever you suspect severe trauma to a joint – for example, when your dog experiences a sudden onset of limping, exhibits obvious pain when moving, or refuses to walk, climb stairs, jump up on or down from furniture, or rise from a sleeping position – see a vet as soon as possible, and consider getting a second opinion from a board certified veterinary surgeon. Diseases of joints and surrounding tissues • Osteochondrosis is a disturbance in the formation of normal cartilaginous tissue; it’s considered a congenital or inherited disease. Immature articular cartilage separates from the underlying bone and floats free in the joint cavity, causing pain, inflammation, and eventually excess bone growth within and around the joint. The disease may affect the shoulder, elbow, stifle, or hock joints. Osteochondrosis typically develops in large breed dogs, and the lesions occur during the maximal growth phase of the skeleton – when the dog is four to eight months of age. Limiting the growth phase of large breed dogs may help prevent the disease. Floating bits of cartilage (also called “joint mice”) need to be removed surgically, and joint fluid modifiers such as glucosamine may also help with repair and prevent further damage to the articular surfaces. Acupuncture may also speed healing. Prognosis for recovery is excellent for shoulders, good for the stifle, and fair for the elbow and tarsal (hock) joints. • Elbow dysplasia is a generalized term that describes several entities, all of which result in abnormal elbow joint function (some of which seem to be genetic). Elbow problems typically develop in young, large, rapidly growing dogs – affected animals demonstrate abnormal bone growth, joint stresses, or cartilage development. The joint is painful, causing the dog to limp, and radiographs are often needed to confirm the various conditions. Treatment is the same as for osteochondrosis, discussed above. • Hip dysplasia may be the biggest joint problem to confront dog owners and breeders in this country. This multifactorial disease affects a high number of dogs, and we don’t yet have a good handle on what causes it, nor what is an effective cure. Further, there is a definite genetic component to hip dysplasia, but the genetics aren’t clear-cut. Some dogs that aren’t supposed to be affected (according to statistical probability) are, and visa versa. While hip dysplasia is far too vast a topic to cover in this article, the following observations may be helpful. Excessive growth, exercise, nutrition, and hereditary factors all affect the occurrence of the disease. Dogs who grow too rapidly for the amount of muscle mass surrounding their hip joints are more prone to joint laxity, which in turn allows for excess movement within the joint. As the joint becomes increasingly unstable, its excessive movements lead to inflammation and ultimately degenerative joint changes – fibrosis, bony growths around the joint, flattening of the femoral head and the acetabulum (the socket joint of the hip that the “ball” of the femoral head fits into), and possibly subluxation or luxation of the femoral head. The changes of hip dysplasia tend to be progressive; however, dogs do not always have symptoms that correspond to the severity of the changes evident on radiographs. Some dogs are practically immobile with only slight changes; others might have severe changes but appear symptom-free. Dogs with symptoms have varying degrees of lameness that tend to get worse with exercise. The first sign of hip dysplasia is often a dog’s reluctance to climb stairs or difficultly when getting up or lying down. Some dogs with hip dysplasia may exhibit a rabbit-like, hopping gait when running. Radiographs help determine the amount of physical damage to the joint, but don’t always correlate with the dog’s symptoms. Prevention efforts are primarily aimed toward identifying potentially affected individuals (with screening X-rays and palpation) and removing them from the breeding pool. There is new interest in the potential of gene mapping. Each of the methods has its own strengths and shortcomings. Look for a board certified veterinary radiologist to do any final evaluations. Conventional treatments include pain relief and various forms of surgery. I’ve found alternative medicines to be especially helpful for hip dysplasia; I use a combination of acupuncture and chiropractic along with nutritional and nutriceutical remedies and possibly herbal support. • Septic or infectious arthritis can be from penetrating trauma (including surgery) or from a spread of infection from other parts of the body. Pain and swelling are common symptoms of infected joints. A needle biopsy of the joint may reveal increased numbers of white blood cells and possibly the instigating microorganism; X-rays may indicate inflammatory response and/or bony changes. Due to the lack of an abundant blood supply to the area, joint infections often require high doses of the specific antibiotic indicated for the microorganism involved. • Immune-mediated arthritis is the consequence of secondary deposits of immune complexes within joints, usually affecting all the joints of the body. These immune complexes cause an inflammatory response that may erode the joint surface (rheumatoid arthritis) or be nonerosive as with systemic lupus erythematosus (SLE). Joints swell and are painful, the dog becomes lame, and he may run a fever and refuse to move or eat. Treatments are aimed at eliminating the pain and rebalancing the immune system. The immune-mediated diseases are another area where I’ve had especially good results using alternative medicines. Most of the alternative approaches (especially acupuncture, homeopathy, and herbal remedies) can help balance the immune system while the remedies are being directed toward specific areas of disease. • Neoplastic arthritis is rare – fortunately, because it tends to be an aggressive neoplasia; the usual recommendation is to amputate the limb. • Trauma to joints is not uncommon. It may present itself in several ways: Joint fractures may occur in any joint, but they are most common in immature animals. They typically occur within the joint, at the growth plate (physis) of the bone, which is its weakest point. The goal for treating a joint fracture is to bring the fractured ends back together and to hold them there until healing takes place. Ligament tears and ruptures are also common. Pain and swelling are evident, and the intensity of the symptoms depends on the extent of the tear. The anterior/cranial and posterior/caudal cruciate ligaments help stabilize the knee joint by crossing from lateral to medial (thus the term “cruciate”) and spanning across the joint from the femur to the tibia. Rupture of the anterior cruciate ligament is a fairly common occurrence. It is caused by excessive trauma, weakened ligaments from immune-mediated causes, and/or poor conformation (straight-legged dogs). Diagnosis of a cruciate ligament is made through palpation (to discern the amount of abnormal movement of the knee) and x-rays. Some dogs recover without any treatment; others respond to weight reduction, immobilization of the joint, acupuncture, and physical therapy; still others will require surgical repair. Surgery typically grafts a tendon from another part of the dog’s body to act as a replacement for the one torn. • Traumatic dislocation of the hip, or hip luxation, is often the result of being hit by a car. It results in lameness, pain when the leg is manipulated, and a shortened affected limb. Treatment either involves nonsurgical manipulation of the limb to reposition it, followed by the use of slings to maintain it in the joint, or surgical stabilization using pins or sutures. Treatment overview Treating any ongoing arthritic problem, no matter its cause, involves the following: • Halting the initial reason that caused the inflammatory process • Repairing the damage already present • Returning the joint (as much as possible) to normal function; without function, the joint will ultimately fuse • Enhancing the healing process. Repair of the damaged surface of a joint depends on several factors, including: • Removal of the inciting cause. Examples include removing exostoses and joint floaters, eliminating infection, or rebalancing the immune system in the case of immune-mediated arthritis. • Return to a more normal joint movement (if possible). • Pain control. Returning to normal joint movement usually requires some easing of existing pain, either via acupuncture, chiropractic adjustments, or herbal (or other) remedies. And, a joint will remain normal only if its functional way of moving has returned to near-normal. • Provide the necessary basics for healing, using nutrients and nutriceuticals Natural medicines for joints I consider chiropractic and acupuncture as the one-two punch for any problem involving the musculoskeletal system; both are especially effective for treating joint conditions. Chiropractic is used in an attempt to return the joint to its normal function – a necessary prerequisite for any long-term healing of the joints. Acupuncture is a proven therapy for alleviating pain and enhancing the immune system. Plus, it may offer a necessary “energetic” to enhance healing. Homeopathic remedies, especially when used in the classical way, may be curative for joint diseases, but I generally consider them to be more helpful as an acute therapy for pain. Remedies that I have found to be effective for my patients include: Arnica, used early-on for acute pain; Rhus tox for the “rusty gate” syndrome – the limp that gets better with use; Byronia for the limp that gets worse with movement; Hypericum for pain; and Ruta for deep pain. Massage and physical therapy can be vital therapies to help in the healing process. These methods help eliminate pain, and physical therapy, in particular, helps return the joint’s normal function by helping it move through its normal range. There are dozens of herbs that can be helpful for treating joint diseases, and they can be especially helpful for providing nontoxic pain relief and for balancing the immune system. In addition, there are some herbs that have been used to treat specific joint problems. Check with an herbalist who has some experience using herbs to treat animals for the appropriate herbs and their dosages. [Editor’s note: Also see Dr. Kidd’s book, Dr. Kidd’s Guide to Herbal Dog Care.] Nutrients and nutriceuticals. There has been much recent buzz about using nutrients and nutriceuticals for joint healing, and the interest has been for good reason – many, if not most, animals with joint conditions respond to varying degrees after a month or so of treatment. There are several of the glycosaminoglycans (GAGs) and proteoglycans that have been used. The most popular are glucosamine (the basic building block for cartilaginous tissue) and chondroitin sulfate, which prevents other body enzymes from degrading the building blocks of joint cartilage. Methylsulphonylmethane (MSM) is another substance that is often added to “joint-repair” mixtures. It supplies needed sulphur molecules and seems to provide additional pain relief. There are a variety of these products available commercially, and even some of today’s commercial dog foods contain them (although probably not in amounts that could possibly be therapeutic). My own experience would indicate that it will take your dog at least 30 days to respond to any of the nutriceuticals mentioned. Further, one product does not fit all; in my experience, some dogs respond to one product and not others, and visa versa. If one product doesn’t seem to be working after a few months trial, first try increasing the dosage for a month or so. If that doesn’t work, try another product. In every case I can think of, we have eventually come up with a product that seems to be helpful. Recent evidence indicates that the Omega-3 fats are beneficial for helping with the joint healing process. Manganese is needed for healthy cartilage formation and it is used in several enzymatic processes in the body. Supplemental vitamin C (especially in the form of sodium ascorbate) is also beneficial for tissue healing. For dosages and method of application of the nutriceuticals and nutrients, check with your holistic veterinarian. Also With This Article “Joint Supplements for Dogs” “Identifying Arthritis in Dogs” -Dr. Randy Kidd earned his DVM degree from Ohio State University and his PhD in Pathology/Clinical Pathology from Kansas State University. A past president of the American Holistic Veterinary Medical Association, he’s author of Dr. Kidd’s Guide to Herbal Dog Care and Dr. Kidd’s Guide to Herbal Cat Care.