New Pain Management for Canine Arthritis

New pain treatments for dogs with arthritis are on the horizon.
By Sarah Wooten DVM, June 2017

According to experts from the University of Pennsylvania School of Veterinary Medicine (Penn Vet), 60 percent of dogs over the age of seven suffer chronic discomfort from degenerative joint disease, more commonly known as arthritis. It often goes unnoticed by the dogs’ owners, however, because they are not familiar with the signs. Humans talk about pain, and express it by crying or wincing. Dogs will rarely vocalize unless the pain is acute—a toenail cut too short, stomach distress, a broken bone.

Signs of chronic discomfort are subtle and can come on so gradually that the dog’s person often doesn’t notice until a veterinarian points out the changes. A dog who’s uncomfortable may slow down, reluctant to run as fast or walk as far as she once did. She may be stiff after lying down, or take longer to get up and moving when it’s cold or damp outside. An uncomfortable arthritic dog may be grumpier, sleep more and decline to take part in games she used to love.

Unsure if your dog is suffering from arthritis? One of the easiest ways to tell is with a trial of pain medication. Talk with your veterinarian about your concerns, and request a week’s worth of anti-inflammatory medication. While your dog is on the medication, keep a diary and note changes in her behavior. People are often amazed at how youthful their older dogs act once their discomfort is relieved.

Penn Vet assistant professor of small animal surgery Kimberly A. Agnello, BA, DVM, MS, one of the nation’s foremost researchers in canine pain management, has some advice on how people can help their arthritic dogs feel better.

According to Dr. Agnello, one of the easiest, most cost-effective and beneficial ways to reduce pain associated with arthritis is to maintain dogs at their healthy weight. She described a recent patient with hip dysplasia who came to her overweight and in pain from arthritis. The dog was scheduled for hip surgery, but first the dog’s owner was instructed to put the dog on a diet. Turns out that when dog lost weight, he improved so much that he ended up not needing surgery. The dog felt better and his owner saved money on food as well as on the procedure.

Once the pain is controlled, strengthening in the form of rehabilitation exercises is vital to maintaining strength and mobility; even one visit to a canine rehab veterinarian for instruction in how to do these with your dog can be useful. Dogs can also be helped by alternative therapies such as joint supplements (high quality fish oil is an excellent choice; check with your vet for the appropriate dosage), acupuncture and cold laser.

When it comes to medication, non-steroidal anti-inflammatory drugs (NSAIDs) continue to be the mainstay of pharmaceutical treatment for canine arthritis. These drugs are relatively safe, and generic forms are available. Dogs on NSAIDs long-term require annual blood work to check liver and kidney function.

As with humans, one size does not fit all when it comes to NSAIDs. Most commonly, a veterinarian will start by recommending carprofen, which has been around a long time, is highly effective, more affordable in the generic formulation and tolerated well by most dogs. It may sometimes provoke an upset stomach or diarrhea, and abnormal changes in blood work may also be seen. In that case, most veterinarians will reach for a second or third NSAID, such as deracoxib, meloxicam or firocoxib.

A new anti-inflammatory drug, grapiprant, was approved by the FDA last year for management of chronic canine arthritis pain. A prostaglandin receptor antagonist, it specifically blocks the EP4 receptor, which is the primary receptor involved in arthritis pain. It is considered safer than many of the other NSAIDs available because its mechanism of action is so specific, meaning that it does not affect other systems in the body like other NSAIDS might. Grapiprant is labeled for use in dogs as young as nine months of age, which makes it a good drug for those with early-onset arthritis from hip or elbow dysplasia, but should not be used for dogs smaller than eight pounds.

For Dr. Agnello, the most exciting and promising advances in the treatment of arthritis in dogs are likely to come from what are known as translational studies. Arthritic dogs are an almost perfect model for arthritic humans, which means that while researchers are developing new treatments for arthritis in humans, dogs also benefit (and vice versa). Treatments designed to resurface cartilage, partial joint replacements and transplanted ligaments are all being actively explored even as you read this article. Studies to improve blood supply to cartilage are also on the horizon, providing more options than ever before. It is truly an exciting time.

Dr. Agnello believes that joint-specific treatments are also the future of pain management. One such possibility is a compound called resiniferatoxin (RTX), a naturally occurring chemical found in red-hot sap produced by a Moroccan cousin of the chili pepper plant. When the chemical —which is about 1,000 times more potent than capsaicin, the active ingredient that gives chili peppers their kick—makes contact with pain-transmitting nerve cells, it spurs a rush of calcium into the cells, destroying them and providing relief from pain.

Presently, RTX can only be delivered by spinal injection, and patients must be anesthetized. When RTX is injected into the spinal fluid, pain cells are permanently ablated, or destroyed, and pain is eliminated. This selective deletion of pain-receptor cells has been coined “molecular neurosurgery” and has the advantage of sparing neurons that are in charge of other functions, such as gross motor movement and feeling. Consequently, the dog is pain free, can maintain coordinated movement, perform activities of daily living and experience a good quality of life.

The Penn Vet research team also studied RTX’s ability to reduce pain in dogs with bone cancer. Anyone who has ever watched a dog suffer from this disease knows that the pain can be debilitating. After receiving injections of RTX, dogs who were virtually immobile were able to run and jump almost as though they felt no pain at all. The cancer persisted—and eventually proved fatal—but owners reported weeks to months of happy times with their dogs. RTX could eventually provide veterinarians with another tool in the ongoing fight to relieve pain associated with arthritis. Other exciting advancements in arthritis treatment and prevention include research into joint-specific stem cells and long-lasting intra-articular treatments.

So, stay tuned: many new, exciting options will be available to veterinarians and pet owners in the near future.

 

Note: The interviews in this article were sponsored by Big Barker.

Sarah Wooten is a small animal veterinarian and certified veterinary journalist. She practices in Greeley part time at Sheep Draw Veterinary Hospital, and writes for multiple online and print publications.