In dogs, as in humans, osteoarthritis (OA) is the most common form of joint disease recognized. OA often leads to physical incapacity and pain, leading to a reduction in the pet’s quality of life. Veterinarians are uniquely positioned to discuss potential changes in mobility with pet owners.
OA is a slowly progressive condition characterized by two main pathologic processes: degeneration of articular cartilage with a loss of both proteoglycan and collagen; and proliferation of new bone. Furthermore, there is a variable, low-grade inflammatory response within the synovial membrane. In North America, age-specific prevalence values range from 20% in dogs older than one year and up to 80% in dogs older than eight years, based on radiographic and clinical data from referral settings.1,2
Goals for managing OA are multifaceted
- Reducing pain and discomfort
- Decreasing clinical signs
- Slowing disease progression
- Promoting repair of damaged tissue
- Improving the dog’s quality of life
Therapy for dogs with mobility issues include a combination of anti-inflammatory and analgesic medications, disease-modifying osteoarthritis agents (DMOAs), nutraceuticals, weight reduction, exercise programs, physical therapy and therapeutic foods. Applying a personalized blend of these management options to each patient improves quality of life, which is the goal of therapy.
Obesity is epidemic in humans and in companion animals. The Association for Pet Obesity Prevention found nearly 56% of dogs to be clinically overweight or obese.3 The CDC estimates that approximately 42% of all adult humans suffer from arthritis.4 Similarly, 20% of the adult canine population is estimated to suffer from osteoarthritis (OA). One long-term study documented that the prevalence of osteoarthritis is greater in overweight or obese dogs compared to ideal weight dogs (83% vs 50%).5 Given these statistics, it’s reasonable to assume a significant portion of arthritic dogs will be overweight or obese and vice versa. Managing these co-morbid conditions presents a variety of challenges.
Assessment
The veterinarian plays an extensive role in assessing and managing joint disease. Diagnosis of osteoarthritis involves a combination of history, physical examination findings and radiographic evidence of joint disease. Historical clues—although essential to creating an index of suspicion—may be elusive and clinical signs may be subtle on routine veterinary examination. Owners don’t always recognize pain or may attribute various signs of OA to normal aging. Thus, they often neglect to report them, unless the veterinarian prompts them during the history.
Signs Associated with Joint Disease
The veterinary team should be aware of the most commonly reported clinical signs of joint disease: difficulty rising from rest, stiffness or lameness. However, a thorough history specific to joint disease may uncover evidence of subtle changes earlier; reluctance to walk, run, climb stairs, jump or play. Signs may be unassuming, like not keeping pace on walks. Pet owners are often unaware of the correlation between behavior changes and joint disease. Yelping or whimpering and even personality changes, such as withdrawal or aggressive behavior, may be indicative of the chronic pain of joint disease.
It’s important for veterinary teams to listen to owners as they describe their dog no longer wanting to walk on tile or hardwood floors, or go for rides in the car—once a favorite activity. This discussion lends clues to uncovering behavior that points to discomfort due to joint disease. The veterinary team may also discover discreet signs that the owner didn’t notice, like longer nails indicating the dog isn’t walking or walking as much, resulting in the nails not being “worn” by hard surfaces; or abnormal fur patterns over joints, indicating the dog has been licking the area—a sign of joint pain. Consistent use of an owner questionnaire (LEFT) may facilitate early detection of osteoarthritis.
Diagnosing obesity may seem inconsequential when dealing with joint disease, but documenting obesity leads to diagnostic, curative and preventive strategies that are omitted in the absence of a diagnosis. The first step to diagnosing overweight or obesity is consistent recording of both body weight and body condition score. The body condition score (BCS) is a subjective assessment of an animal’s body fat percentage, accounting for the animal’s frame size independent of its weight. It’s important for the veterinary team to align on the BCS protocol and ensure all members are following the protocol. The BCS puts body weight in perspective for each individual patient. In both human and veterinary medicine, timely identification of overweight or obesity by primary care providers remains the crucial initial step in their management.
Risk factors for canines to develop osteoarthritis include age, large or giant breeds, genetics, developmental orthopedic disease, trauma and obesity. Risk factors for overweight or obesity in dogs include age, particular breeds, neutering, consuming a semi-moist, homemade or canned food as their major diet source, and consumption of “other” foods (meat or other food products, commercial treats, table scraps).
The radiographic prevalence of canine hip dysplasia, a leading cause of OA in dogs, has been reported to be as high as 70% in Golden Retrievers and Rottweilers.6 Veterinarians must be cognizant of the overrepresentation of obesity in certain breeds (Golden Retrievers, Rottweilers, Labrador Retrievers), and begin discussions about ideal body weight when these patients are young. Reiterate the fact that chubby puppies become overweight adult dogs and thus should be educated regarding the importance of lifelong weight management.
Studies show that dogs evaluated as overweight at nine to 12 months were 1.5 times more likely to become overweight adults.7,8 The incidence and severity of OA secondary to canine hip dysplasia can be significantly influenced by environmental factors such as nutrition and lifestyle. Understanding the correlation between maintaining their dog at a healthy weight and decreasing the risk of disease may be a powerful motivator for many owners.
In humans, the epidemic of obesity is largely attributed to changes in the availability, quantity and composition of food, and the decrease in the amount of physical activity needed for daily living. Physical activity levels of dogs often mirror their human companions. Veterinary teams should educate dog owners—regardless of the owners’ body condition—that dogs’ needs are not a constant request for food. If their dog approaches them while cooking, it’s not a plea for food, but attention. Pet, talk to or interact with the dog, but don’t give a food item for each interaction. Veterinarians have the ability to counsel owners on appropriate responses early in the dog’s life, and owners should be encouraged to respond with play activities or praise rather than food rewards.
Managing Mobility Nutritionally
As with many diseases, nutrition plays a role in managing joint disease. Nutritional factors can potentially modify some of the underlying processes involved in arthritis, including modulation of the inflammatory response, provision of nutrients for cartilage repair and protection against oxidative damage. Nutritional management may also help reduce or eliminate the need for conventional drugs— some which are associated with adverse, secondary effects.
Nutrients & Their Role in Managing Joint Disease
Amino acids, the building blocks of proteins, play a role in the structure of tissues and organs in the body. Methionine is a unique amino acid that produces several important molecules in your body which are essential for the proper functioning of cells. Methionine contains sulfur and can produce other sulfur-containing molecules in the joint, and is also involved in protein production. Manganese is an essential nutrient involved in numerous chemical processes in the body, including bone formation. Manganese supports the health and maintenance of bone and cartilage in joints. Manganese also supports collagen formation for joint strength. Methionine and manganese are building blocks for cartilage in joints.
A crucial amino acid which facilitates the body turning fat into energy is carnitine, which aids in maintaining muscle and transporting long chain fatty acids and their derivatives into the mitochondria of cells. The severity of joint disease may be lessened by strengthening skeletal muscle and turning fat into energy.
Hyaluronic acid (HA) is a principal component of synovial fluid. HA works in the joint to preserve joint viscosity, support lubrication of the joint and aid in shock absorption. Antioxidants and vitamins C and E neutralize free radicals to increase mobility. N-Acetyl D-glucosamine “shortcuts” the glycosaminoglycan pathway to maintain healthy joint structure and function.
Omega-3 fatty acids have been shown to aid in the management of dogs with osteoarthritis. Studies show, foods with high levels of total omega-3 fatty acids and eicosapentaenoic acid (EPA) can improve the clinical signs of canine osteoarthritis.9,10 In normal canine cartilage, there’s a balance between synthesis and degradation of the cartilage matrix. Consequently, in arthritic joints, damage to chondrocytes stimulate a viscous cycle resulting in the destruction of cartilage, inflammation and pain. Omega-3 fatty acids demonstrate clinical benefits, including the control of inflammation and the reduction of the expression and activity of cartilage degrading enzymes.
Cartilage degradation starts with loss of cartilage aggrecan followed by loss of cartilage collagens, resulting in loss of ability to resist compressive forces during joint movement. Eicosapentaenoic acid (EPA) significantly decreases the loss of aggrecan in canine cartilage by inhibiting the up regulation of aggrecanases by blocking the signal at the level of messenger RNA.
Omega-3 fatty acids result in a decrease in membrane arachidonic acid (AA) levels because omega-3 fatty acids replace AA in the substrate pool. This produces an accompanying decrease in the capacity to synthesize inflammatory eicosanoids from AA. Studies have documented that inflammatory eicosanoids produced from AA are depressed when dogs consume foods with high levels of omega-3 fatty acids. In addition to their role in modulating the production of inflammatory eicosanoids, omega-3 fatty acids have a direct role in the resolution of inflammation.
Shellfish supplements have been used to manage arthritis in humans, and, recently, interest has focused on the potential benefits of a nutritional supplement prepared from the New Zealand green lipped mussel, Perna canali culus. Green lipped mussel (GLM) is known to contain anti-inflammatory components and other nutrients which benefit joint health. Heat processing of GLM has been shown to destroy its activity. Therefore, the processing of whole GLM and incorporation of the GLM product into food and supplement products require special care and processing techniques to avoid destroying any efficacy of the final product.
GLM has been shown to contain a unique omega-3 fatty acid, eicosatetraenoic acid (ETA), which appears to act as a dual inhibitor of arachidonic acid oxygenation by both the cyclooxygenase and lipoxygenase pathways.11 GLM is a rich source of nutrients, including glycosaminoglycans (GAGs), such as chondroitin sulfates, vitamins, minerals and omega-3 series PUFAs.
Managing joint disease in dogs successfully requires a comprehensive approach including preventive measures and a multimodal management program. Early diagnosis of OA facilitates early intervention which will likely improve the long-term outcome for the patient. It’s important for veterinarians to use a thorough, disease-specific history as this may raise awareness of subtle changes early in the course of joint disease, as well as communicate the importance of nutritional management in the successful management of joint disease. +
References:
- Johnston SA. Osteoarthritis – joint anatomy, physiology, and pathobiology. Veterinary Clinics of North America-Small Animal Practice. 1997;27:699–723. doi: 10.1016/S0195-5616(97)50076-3.
- Anderson KL, O’Neill DG, Brodbelt DC, et al. Prevalence, duration and risk factors for appendicular osteoarthritis in a UK dog population under primary veterinary care. Scientific Reports. 2018. 8:5641, 1-12.
- https://petobesityprevention.org/ accessed April 24, 2020.
- Hales CM, Carroll MD, Fryar CD, Ogden CL. Prevalence of obesity and severe obesity among adults: United States, 2017-2018. NCHS Data Brief No. 360, February 2020.
- Kealy RD, Lawler DF, Ballam JM, et al. Evaluation of the effect of limited food consumption on radiographic evidence of osteoarthritis in dogs. JAVMA 2000;217:1678-1680.
- Paster, E. R., E. LaFond, et al. Estimates of prevalence of hip dysplasia in Golden Retrievers and Rottweilers and the influence of bias on published prevalence figures. JAVMA, 2005, 226(3): 387-392.
- Eby J, Colditz G. Obesity/Overweight: Prevention and Weight Management. In: Quah S, Heggenhougen K, eds. International Encyclopedia Of Public Health St. Louis: Elsiver, 2008:602-609.
- Kienzle E, Bergler R, Mandernach A. A comparison of the feeding behavior and the human-animal relationship in owners of normal and obese dogs. J Nutr 1998;128:2779S-2782S.
- Roush JK, et al. Multicenter practice assessment of the effects of omega-3 fatty acids on osteoarthritis in dogs. JAVMA, 2010; 236 (1): 59-66.
- Fritsch D, Allen TA, Dodd CE, et al. Dose-titration effects of fish oil in osteoarthritic dogs. J Vet Intern Med 2010;24:1020-1026.
- Treschow AP, Hodges LD, Wright PF, et al. Novel anti-inflammatory omega-3 PUFAs from New-Zealand green-lipped mussels, Perna canaliculus. Comp Biochem Physiol B Biochem Mol Biol 2007;147:645–656.
