Sarah J. Wooten, DVM
Theres a lot of crazy info out there when it comes to canine joint health and mobility. (Elk antler, anyone?) Arm yourself with the evidence and position your veterinary practice as the trusted source of reliable data.
Whether their dogs are old and stiff, young and developing, or couch potatoes, pet owners tend to be highly concerned about canine joints. They're searching online for information on mobility and arthritis, asking each other for recommendations, or going with what's been recommended by their own doctor.
Chances are they've already come to you with questions about things like hyper-immune milk factor and Boswellia serrata, but how do you begin to shed light on the veiled world of nutraceuticals? How much to give? How often? What brand? Glucosamine-enriched dog food or shark cartilage supplement? What is truth? What is a “claim”? So many questions.
Fortunately, when it comes to evidence-based use of joint supplements in dogs, CVC educator-now Fetch dvm360 conference-Matt Brunke, DVM, CCRP, CVPP, CVA, has the answers. You know pet owners are going to ask you for your opinion. Why not be the expert?
Dr. Brunke's guide to oral joint supplements
Here's a rundown of the joint supplements getting the most buzz in the pet world these days.
Glucosamine hydrochloride. Glucosamine hydrochloride is an amino sugar, but it's not involved in the glucose pathway. It's a building block of the cartilage matrix and stimulates growth of cartilage cells. Glucosamine is readily available, cheap and can be given safely to diabetic patients, Dr. Brunke says.
Notice that we're discussing glucosamine hydrochloride, here, not glucosamine sulfate. Although glucosamine sulfate is absorbed better, there have been no studies published showing that glucosamine sulfate actually shows up in synovial tissue after it's been ingested orally. A joint supplement doesn't help if it doesn't get where it needs to be.
A loading dose of two times maintenance for four to six weeks is required for glucosamine hydrochloride to reach therapeutic levels, Dr. Brunke says. Maintenance is 500 to 1,000 mg for a 75-lb dog, which works out to about 15 mg/kg.
Does it work? A randomized, double-blind, positive-controlled, multicenter trial assessed 35 dogs with confirmed osteoarthritis of the hip or elbow for their response to orally administered glucosamine hydrochloride and chondroitin sulfate. Carprofen was used as the control. Although onset of efficacy was slower than carprofen, dogs treated with glucosamine-chondroitin showed statistically significant improvements in pain scores, severity and weightbearing by day 70.1
Chondroitin sulfate. This supplement works by inhibiting cartilage-destroying enzymes, but it's difficult to source and extract, which raises the cost. Chondroitin is a large molecule with variable absorption, Dr. Brunke says, though some companies produce a low-molecular-weight version that can increase absorption from the gastrointestinal tract.
Chondroitin requires a loading dose similar to glucosamine, and the standalone dosage is the same as glucosamine. When given with glucosamine, chondroitin has a synergistic effect and has been shown to lessen inflammation if given before a joint injury in dogs, Dr. Brunke says.
Avocado soybean unsaponifiables (ASUs). ASUs protect cartilage matrix against damage by inhibiting key mediators of the structural changes that take place in osteoarthritis,2 and they stimulate healing of osteochondral defects in the canine knee, possibly by increasing transforming growth factor (TGF)-beta in the tissues.3 The dosage used in the studies referenced was one 300-mg capsule ASUs every three days, but Dr. Brunke recommends daily administration based on body weight. He adds that the efficacy of ASUs is similar to NSAIDs in dogs, but they have a delay in onset similar to glucosamine and chondroitin. When combined with glucosamine and chondroitin, ASUs modify and amplify the actions of each and reduce the amount of chondroitin required.
Omega-3 fatty acids. Omega-3s are known to support heart health and joints, improve kidneys and boost the immune system, but the dosage for each condition varies. For example, the dose needed for kidneys is one-fifth the dose needed for joints, Dr. Brunke says. When it comes to omega-3s, docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) from wild-caught coldwater fish is best. Farm-raised fish have low levels of omega-3s and high levels of omega 6s, Dr. Brunke says.
One study found that some dogs receiving carprofen for osteoarthritis pain that were also fed a diet supplemented with fish oil omega-3 fatty acids needed less carprofen.4 Dr. Brunke recommends a dosage of 100 mg/kg combined EPA and DHA for osteoarthritis. FYI-in case your clients ask, flaxseed does not provide sufficient amounts of DHA and EPA in dogs.
MSM/DMSO. There has been no published research on the use of these supplements in dogs, Dr. Brunke says.
Eggshell membrane. Eggshell membrane contains high concentrations of glucosamine, chondroitin, collagen and hyaluronic acid, Dr. Brunke says-but absorption of these nutrients is unknown. There are some good human studies that demonstrate the efficacy of eggshell membrane in treating osteoarthritis, he adds, and while there are no published studies in dogs, Virbac recently launched a veterinary product called Movoflex.
Green-lipped mussels. The mechanism of green-lipped mussels has not been determined, Dr. Brunke says, but a 2013 study found increased concentrations of plasma omega-3 fatty acids and improvement of peak vertical force in dogs fed a diet enriched with green-lipped mussel.5 Still, studies do not demonstrate consistent improvement, and there are some concerns about the efficacy of farmed mussels and the sustainability of harvesting wild-caught mussels, he says. Standard dosage is 77 mg/kg.
Boswellia serrata. This tree extract is said to have an NSAID-like effect. A 2004 study showed statistically significant reduction of severity and resolution of the signs of osteoarthritis in dogs, such as intermittent lameness, local pain and stiff gait, after six weeks of treatment with Boswellia serrata.6 Note that the study was unblinded, based on subjective data and not placebo-controlled, Dr. Brunke says. Standard dosage is 50 mg/kg.
Your clients might ask you about …
Arm yourself for the next round of client questions with info on these substances.
Curcumin. One study showed that curcumin inhibited macrophage proliferation related to a strong downregulation of TNF-alpha and fibrinolysis activation, suggesting that curcumin offers anti-inflammatory support for osteoarthritis treatment in dogs.7 But standard extracts are not well-absorbed in dogs, making this a less-effective joint supplement. And turmeric, from which curcumin is derived, is not safe or efficacious for pet health.
How to evaluate products
When it comes to nutraceuticals, Dr. Matt Brunke is concerned with two things: safety and efficacy.
In veterinary medicine, a nutraceutical is defined as a nondrug substance produced in a purified or extracted form that is intended to improve health and well-being. Nutraceuticals are not drugs; they are considered food and regulated as such. This can lay the groundwork for contamination and variability because there is no direct regulatory oversight and no requirement for studies to prove efficacy and safety. Be cautious, Dr. Brunke says, when evaluating product labels and claims. Last year alone there were more than 22,000 human trips to the ER directly related to consumption of joint supplements alone.
Labels can be confusing, Dr. Brunke says. Just because a nutraceutical label claims something doesn't make it gospel. Look for evidence that a product works, like double-blind placebo studies, studies done by an independent third party, prospective studies or studies published in peer-reviewed journals. Dr. Brunke recommends calling the company and asking for research-if they can't give you any, that's a major red flag.
Elk or deer antler. Yes, you heard that right-have you seen NFL players chewing on antlers on the sidelines? A 2004 study showed improvement in dogs diagnosed with osteoarthritis when administered high-quality elk velvet antler powder supplement.8 The mechanism of action is not known and a dosage has not been established, Dr. Brunke says. This probably goes without saying, but the antler chew toys from the pet store do not contain the active ingredient.
Hyper-immune milk factor. Duralactin reduces inflammation by blocking neutrophils from entering the endothelial wall. This supplement has been studied extensively in people but is yet to be determined efficacious in dogs, Dr. Brunke says.
Muscle recovery and strengthening supplements
Does your patient need to build muscle, and you are thinking a muscle-building supplement might help? Are clients asking you about creatine and whey protein for their dogs? Here's the lowdown.
Creatine. Creatine is used by people for muscle building and recovery. The kicker is that creatine requires anaerobic activity, such as weightlifting, to be effective. In other words, Dr. Brunke says, if you put creatine in your protein shakes and you aren't doing weightlifting exertion within 30 seconds, all creatine does is make you fat. In general, creatine is probably OK for gym rats and maybe for flyball dogs, but do we really want our canine athletes jacked out like Arnold Schwarzenegger? Dr. Brunke doesn't think so.
Whey protein. Whey protein is derived from milk. The dosage and efficacy is unknown in dogs, Dr. Brunke says.
Chromium. Chromium is marketed to build muscle in people, but there are no studies in dogs. While chromium supplementation has been found to help people with diabetes, it does not help diabetic dogs, Dr. Brunke says.
Dimethyl glycine. This supplement is marketed to decrease lactic acid buildup. There is no research in dogs.
Lecithin. Lecithin is an emulsifying agent marketed to support athletic performance. Again, there's no data available for dogs.
More tips from Dr. Brunke
Now that you've got an overview of which supplements might assist your canine patients, consider these helpful hints:
> Start chondroprotective agents as early as possible in large-breed dogs or dogs predisposed to development of osteoarthritis. Joint supplements can be given to puppies as young as 8 weeks of age that are predisposed to development of osteoarthritis due to conformation or injury. The main concern is gastrointestinal upset.
> The omega-3s in most maintenance diets are not high enough to treat disease states. If an arthritic dog is eating a maintenance diet formulated with omega-3s, the owner will need to administer an omega-3 supplement on top of that to attain therapeutic levels.
> Glucosamine hydrochloride and chondroitin sulfate work, but the onset of action is slow. Cover your patient's pain with an NSAID for two to three months, then titrate the NSAID down to the lowest dose necessary to control pain. Some dogs can come off the NSAID completely.
> Joint supplements are a waste of the client's money if the dog has end-stage bone-on-bone osteoarthritis in every joint. Don't bother. But if just one joint is affected, supplements may be given to protect the other joints.
> Many dog treats contain glucosamine and chondroitin, but look at the label! Most of these treats would require the pet owner to feed obscene amounts of treats to get therapeutic levels of glucosamine or chondroitin. Another waste of money.
> Speaking of wasting money, help your clients calculate whether they're really saving money on over-the-counter fish oil products. The dosage required for dogs with osteoarthritis is 5,000 mg/day EPA and DHA for a 50-kg dog. That's equal to three pumps of Welactin twice daily, three cups of Hill's J/D twice daily, or 25 capsules of omega-3s (depending on the brand) twice daily. At the dosages required to treat osteoarthritis, OTC products often are not cost-effective.
As veterinarians, we need to be advocates of disease prevention and judicious supplement use. There are a number of reputable products available, so it's essential for us to have good communication with the manufacturers, educate ourselves and then make informed decisions with our clients. They need us to help them wade through the plethora of information out there-we will build value in our knowledge, expertise and goodwill by helping them in this often-confusing area.
1. McCarthy G, O'Donovan J, Jones B, et al. Randomised double-blind, positive-controlled trial to assess the efficacy of glucosamine/chondroitin sulfate for the treatment of dogs with osteoarthritis. Vet J 2007 174(1):54-61.
2. Boileau C, Martel-Pelletier J, Caron J, et al. Protective effects of total fraction of avocado/soybean unsaponifiables on the structural changes in experimental dog osteoarthritis: inhibition of nitric oxide synthase and matrix metalloproteinase-13. Arthritis Res Ther 2009;11(2):R41.
3. Alt?nel L, Sahin O, Köse KC, et al. [Healing of osteochondral defects in canine knee with avocado/soybeanunsaponifiables: a morphometric comparative analysis]. Eklem Hastalik Cerrahisi 2011;22(1):48-53.
4. Fritsch DA, Allen TA, Dodd CE, et al. A multicenter study of the effect of dietary supplementation with fish oil omega-3 fatty acids on carprofen dosage in dogs with osteoarthritis. J Am Vet Med Assoc 2010 236(5):535-539.
5. Rialland P, Bichot S, Lussier B, et al. Effect of a diet enriched with green-lipped mussel on pain behavior and functioning in dogs with clinical osteoarthritis. Can J Vet Res 2013;77(1):66-74.
6. Reichling J, Schmökel H, Fitzi J, et al. Dietary support with Boswellia resin in canine inflammatory joint and spinal disease. Schweiz Arch Tierheilkd 2004;146(2):71-79.
7. Colitti M, Gaspardo B, Della Pria A, et al. Transcriptome modification of white blood cells after dietary administration of curcumin and non-steroidal anti-inflammatory drug in osteoarthritic affected dogs. Vet Immunol Immunopathol 2012;147(3-4):136-146.
8. Moreau M, Dupuis J, Bonneau NH, et al. Clinical evaluation of a powder of quality elk velvet antler for the treatment of osteoarthrosis in dogs. Can Vet J 2004;45(2):133-139.
Dr. Matt Brunke, a speaker at the CVC veterinary conferences, lives in Washington, D.C. Dr. Sarah Wooten is an associate at Sheep Draw Veterinary Hospital in Greeley, Colorado, a CVC (now Fetch dvm360 conference) speaker and a frequent contributor to dvm360.com.