Written by: Alexa Waltz
Have you noticed your best buddy walking stiffly, moving slower when rising out of bed, or hesitating to run and jump lately? They could be feeling the effects of canine arthritis, a very common problem causing discomfort and joint pain in dogs.
What Exactly ARE Joints, Anyways?
In order to understand why and how arthritis is a problem in your pet, it’s necessary to first understand how their body works! Joints act like hinges, linking together rigid bones and the corresponding muscles, which allows dogs to move around at will. When your pup tears across the yard after a squirrel, leaps off the couch, and even plops down to curl up for a nap, you can credit their healthy joints for his flexibility and ability to absorb all of those physical forces. There are several types of joints in a dog’s body, but we will focus on the main type of joint that is most often affected by arthritis. As a dog ages, the synovial joints in the hips, knees, elbows, and shoulders are the most common culprits for mobility issues due to arthritis pain. The vertebrae of the spine can be affected by arthritis and aging related changes too, but that is a subject for a different day!
In a healthy animal (humans included!) a synovial joint contains the smooth, slimy, “padded” surface between 2 or more bones. Each joint has similar components: the hard bones, soft cartilage, pocket of joint (“synovial”) fluid, and supporting structures such as ligaments and a meniscus. In order for your dog to move freely and without pain, every structure inside the joint needs to be healthy, shaped correctly, and located in the right place.
In health, your dog’s joints contain a lubricated and smooth sliding surface, which acts as a shock absorber, and also to maintain proper alignment allowing your dog the freedom of pain-free movement! These qualities are essential for stable and balanced joint function. Healthy joints ensure the best long-term, pain-free movement for your dog.
What is Arthritis?
Arthritis is also referred to interchangeably as “osteoarthritis (OA)” and “degenerative joint disease (DJD)”. These terms mean that one or more joints are inflamed and that the normal structures that make up that joint are no longer healthy.
If a joint is abnormally shaped or if it becomes damaged, then it will become unstable. Damage can happen due to a traumatic injury or can be due to degeneration of the joint itself over time. The instability eventually leads to inflammation and abnormal wear of surfaces within the joint, setting the stage for arthritis.
Once a joint becomes inflamed, then what happens? Your dog’s body is incredible at trying to heal itself, and microscopic changes begin to take place in a vain attempt to restabilize the joint. Blood vessels deliver inflammatory cells to try to wage war on the cause of the instability and start the repair process. Unfortunately, these cells only serve to continue the vicious cycle of inflammation and destruction! Because these inflammatory cells can’t “win” (like they could against, say, a bacterial infection), they keep coming and keep causing more damage.
In the beginning, the damage may be microscopic and involve thinning of the cartilage, depositing blood cells and inflammatory cells in the joint fluid itself, and thickening the lining that provides essential shock absorption. (This structure is called the “joint capsule”–you can think of it like a water balloon between two hard bones!) When the lining of the joint capsule becomes thickened, this contributes to further irritation when your dog is bending and extending the affected joint. This changes the way the surfaces of the joint come in contact with each other, causing further wear and tear.
Eventually, these abnormal forces within the joint cause the nice soft spongy cartilage to wear away, increasing contact between the hard bony surfaces of the joint. Sometimes, pieces of cartilage can even break off! The body will further attempt to try to stabilize the joint by depositing new boney material to form a type of scar tissue. Unfortunately, this attempt is misguided and causes MORE problems–since this changes the joint shape even further, causing more inflammation, more erosion of normal tissue, and more pain. Once a joint is damaged, you can see how the resulting inflammation can cause permanent, progressive, and irreversible changes over time.
When a joint suffers a traumatic injury, it is essential to identify the nature of the injury and assess if urgent treatment may help to minimize these inflammatory changes as much as possible. Sometimes, that treatment includes timely surgery and rehabilitation. By treating joint injuries promptly, stability of the joint is restored which can minimize and even prevent some damaging long-term changes.
When arthritis is already setting in and we do not have a treatable traumatic injury, veterinarians focus on managing the arthritis pain and slowing the progression in order to maximize comfort and mobility for your dog. Check this link for more about common treatments of arthritis in dogs. (LINK: Dog Arthritis treatments).
Predisposing Factors of Arthritis in Dogs
Although any dog can be affected by arthritis, the common “poster child” is a large breed older dog who is slowing down due to hip stiffness and pain (Goldens, Labs, Shepherds, etc, that are 8+ years old). Why are these large breed dogs so commonly affected by arthritis? What might cause a smaller dog to get arthritis?
An arthritic dog tends to fall into one of two general groups: those who were born with their issue, and those that acquired their issue through their life. Let’s go through both scenarios:
Congenital Causes that can Lead to Arthritis
Genetic and developmental issues are among the predisposing factors for arthritis that we have little to no control over. Dogs will inherit conformation (body structural/shape) and skeletal (bone/joint) issues from their parents. Some of the most common heritable issues that can lead to arthritis over time are as follows:
-Hip Dysplasia and Elbow Dysplasia – abnormal formation of the hip and elbow joints
-Osteochondrosis – Abnormal bone/cartilage development
-Luxating Patella – Abnormally shaped femurs (thigh bones) which cause the kneecaps to slip in and out of place
-Bone and joint conformation – Abnormalities in the shapes of a dog’s bones which result in abnormal forces being placed on the joints
AskVet Tip: Some dog breeds are predisposed to congenital and developmental conditions due to the inheritance of traits from their parents. A goal of responsible and selective breeding of purebred dogs is to improve the genetics and physical traits that are passed down to further generations. Genetic testing, X-rays, and blood testing are among some of the ways of avoiding the perpetuation of undesirable health issues. If you are considering breeding your dog, we recommend a detailed discussion with your veterinarian and screening your pup for any congenital issues that may put their offspring at risk of a painful life due to arthritis!
Acquired Causes of Arthritis
Even if a dog was born with stable balanced joints and has strong genetics, there are some aspects of their lifestyle, daily activity, body condition, and environment that can increase their risk of developing arthritis:
-Obesity – Excess body weight can cause abnormal forces to be put on the joints
-Joint Injuries – Rupture of the cranial cruciate ligament in the knee, bacterial joint infections, trauma, immune-mediated and inflammatory conditions, bone fractures, etc
-Joint surgery – Any past surgeries involving the joints can disrupt the healthy surface and structures
-Diet – Lacking appropriately balanced nutrients for healthy growth, especially during puppyhood, can affect the makeup of bones and cartilage
-Strenuous exercise and joint usage – Repetitive high impact movements of performance, working, and sporting dogs
Common Dog Arthritis Symptoms
Dogs are very good at compensating and hiding their discomfort when arthritis is in its early stages. Typically, when dogs are no longer able to cope with the pain, pet parents will start to see some of the signs hinting at arthritis. We primarily see arthritis affecting middle-aged to older dogs, although some younger dogs can also be affected. Here are some of the more common symptoms of arthritis in dogs:
-Moving more slowly
-Hesitant to run and jump
-Slow to lay down or get up from bed
-Limping, or “bunny hopping”
-Swelling or thickened joints
-Difficulty standing on slippery surfaces
-Limited ability to flex or extend joints
-Less playful, reluctant to be active
-Grumpy behavior, sensitive to certain areas of their body being touched
-Depression and unusual behavior
-Postural changes, arched back
-Pacing at night
-Inability to get comfortable
-Sleeping more than normal
-Weakness in hind legs (fall over, legs give out, difficulty posturing to urinate and defecate)
What to do Next?
If your pup’s movement and behavior match some of the above descriptors, it may be time to take her to the vet for an orthopedic exam! Your vet will watch your pup move around the room prior to conducting a full physical exam. During the exam, your veterinarian will be keeping a close eye on your dog’s reactions, looking for areas that are painful or sensitive. They will also assess your dog for decreased muscle mass, thickening and swelling of joint capsules, a crunchy sensation when the joints are flexed, and decreased overall flexibility. Also, a series of special flexion techniques can help determine the presence of certain conditions like a ruptured cruciate ligament.
Your veterinarian’s orthopedic exam may be followed by x-rays to view the health of the bones and look for any obvious visual changes within the joint. Sometimes veterinarians will also recommend blood and urine testing to check the health of the internal organs as well, especially if surgery or daily and long-term pain medication is under consideration.
Your vet will then use all this information to discuss any therapies and a plan for your pup’s condition. Again, since arthritis changes cannot be reversed, management going forward mostly focuses on keeping the pain at the lowest level possible, supporting the current health of the joint structures, and preventing further inflammation and deterioration. Keeping your pup mobile and comfortable for as long as possible is the goal of arthritis management!
Our AskVet team is ready and waiting 24/7 to discuss your dog’s mobility issues, address any questions about arthritis causes, and share general info regarding treatment options. Whether you have an immediate need or are looking to improve your pet’s overall wellbeing, just sign into your account and one of our friendly and knowledgeable veterinary experts will attend to your needs, no appointment required!
Alexa Waltz, DVM
Dr. Waltz was raised near the beaches of Southern California but has spent her adult life living all over the beautiful United States while serving in the military and as a military spouse. She left California for the first time to pursue a career as a veterinarian at Louisiana State University School of Veterinary Medicine and graduated as a Doctor of Veterinary Medicine in 2006. She was accepted into the US Army Health Professionals Scholarship Program during vet school and upon graduation spent her military years as a veterinarian in San Diego working for the US Marine Corps and US Navy Military Working Dog programs as well as caring for pets of service members. After her military service, she became a civilian veterinarian and continued as a small animal general practitioner at clinics in California, Rhode Island, Colorado, and Maryland. Dr Waltz loves to see her “in person” patients just as much as communicating with and assisting pet parents virtually on AskVet. Dr Waltz is also a Mom to 3 humans, 2 guinea pigs, and 1 Australian Shepherd and in her spare time she loves traveling, adventures, exercising, and doing just about anything out in nature!