Osteoarthritis (OA), also known as degenerative joint disease (DJD), is a common problem in small animal patients. An estimated 80% of dogs >8 years old and 60% of cats between 6 and 19 years old have OA.
The slow progressive degeneration of the articular cartilage leads to pain and disability. In severe cases, OA can significantly compromise quality of life. OA may be classified as primary or secondary. Secondary osteoarthritis is due to an identifiable cause and is much more common. Obesity, joint instability (i.e., cranial cruciate ligament rupture, carpal hyperextension), trauma/articular fracture, inflammatory diseases (i.e., septic/ non-septic arthritis), and congenital and developmental abnormalities (i.e., elbow and hip dysplasia, osteochondrosis) are some of the conditions that can lead to secondary osteoarthritis.
Many factors may contribute to the manifestation and progression of OA, including genetics, breed, conformation (low muscle mass), age, sex/neuter status, body weight, and activity. In cats, having outdoor access and having had a previous history of trauma are big risk factors for OA development. Successful management often requires a multimodal approach and regular follow-ups.
Analgesia
Non-steroidal anti-inflammatory (NSAID) drugs are the mainstay of analgesic medications, as they help to alleviate pain associated with inflammation. Initially, the dog or cat may need to be on NSAIDs continuously to control the pain. Dosage should not exceed the recommended dosage range and may need to be adjusted to the patient’s lean weight to avoid overdose. The dosage and frequency of administration can further be adjusted as needed once the pain is controlled and the patient has shown improvements through weight loss and increased mobility.
NSAIDs should be used cautiously in patients with renal disease, hepatopathy, gastrointestinal problems, and endocrinopathy. Geriatric dogs may be more prone to gastric ulceration with continuous usage of NSAIDs.
Cannabinoids (CBD) have increasingly become popular among owners seeking alternative analgesia. Endocannabinoid receptors are widely distributed in the central and peripheral nervous system and synovium, and they play a role in the modulation of pain and inflammation.
Although CBD administration resulted in decreased pain and increased activity level (these dogs were also receiving less gabapentin or had discontinued gabapentin) in some studies, a clinical study looking at ground reaction forces showed no significant difference between CBD products and placebo. CBD seems to be safe overall; however, reported adverse effects include elevated alkaline phosphatase (ALP), sedation (likely from the THC contaminant), and vomiting.
Additional pain medications, such as amantadine, gabapentin, and amitriptyline, can be used to help manage chronic pain via different pathways in dogs. Although not as effective in dogs, tramadol could be considered in cats with OA.
Weight Loss
Orthopedic problems and arthritis are exacerbated by having increased weight/force being placed on the already abnormal joint. Unsurprisingly, weight loss is one of the most effective ways to manage OA. Animals with orthopedic conditions and even normal animals greatly benefit from having a normal to slightly low body condition.
It is important to communicate realistic goals with the owners and make sure everyone involved in the animal’s care is on the same page. Complete omission of treats is often not well-received; however, the amount of treats should be limited to <10% of the total calorie intake. Clear instructions that include specific daily calorie goals and measured amounts of food can help simplify the process and increase compliance for the family.
In a controlled, life-span study in Labrador retrievers by Purina, puppies on a restricted diet (25% fewer calories) not only had less severe clinical signs of OA over time, but they also had ~2-year delayed onset of clinical signs and lived 2 years longer (increased lifespan by 15%). Prescription foods formulated to contain fewer calories and/or higher protein (i.e., Hill’s r/d, Hill’s Metabolic, Purina OM) may allow owners to feed a larger quantity of food while feeding fewer calories. Weight loss should be intentional at a rate of no more than 1% to 2% body weight per week.
Supplements
Numerous supplements claim to provide. OA support, and the options can be overwhelming and costly over time. Among the supplement categories, omega-3 fatty acids, specifically eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), have consistently been shown to result in decreased inflammation in arthritic joints.
Studies looking at omega-3 or lower ome-ga-6:omega-3 polyunsaturated fatty acid supplementation revealed less cartilage degeneration and osteophytes, decreased denatured type II collagen, decreased inflammatory markers, improved subchondral bone parameters, and improved performance and lameness.
Aside from the positive effects on arthritic joints, omega-3 fatty acid supplementation can also enhance wound repair, improve skin barrier and hypersensitivity reaction, promote cardiovascular health, and provide neuroprotection of the brain. High dosages are needed to achieve the desired joint benefits, and diarrhea is not uncommon with administration. Therefore, it is beneficial to start at a lower dose and increase the dosage incrementally until the desired dosage is achieved. (See Colorado State University’s Canine Fish Oil Dosing Chart.)
This supplement can alter the coagulation pathway, so it should be avoided in small animals known to have bleeding disorders. Avocado/soybean unsaponifiables and vitamin E may also reduce pro-inflammatory cytokines and improve pain. No strong evidence has been documented to prove the reliable benefit of glucosamine/chondroitin or other supplements (i.e., green-lipped mussel, turmeric-derived polyphenols). Generally, they are safe with minimal adverse effects and have anecdotal benefits.
By Dr. Monica Chen, DVM, MS, DACVS (Small Animal)
For Dr. Chen’s discussions of physical theraphy, intra-articular injections, and alternative therapies, such as monocloncal antibodies and acupuncture, as well as for references related to this article, please visit: Referral Services.
