Osteoarthritis (OA) is a degenerative disease that affects one or many joints.
The condition is said to be « primary » when there is no predisposing factor involved, whereas it is said to be « secondary » when there is one.
In the first case, OA appears with the wearing down of the joints combined with aging. In the second instance, which happens more often, the joint deteriorates because of instability present there.
This instability occurs following a trauma or a change, progressive or sudden, in the internal structure of the joint (cruciate ligament tear, patellar luxation, hip dysplasia, meniscal injury, etc.).
This instability causes inflammation which induces progressive changes in the joint structures and function.
Unfortunately, the treatment of OA is palliative and not curative. However, it is possible to delay the progression of the degenerative changes happening in the joint and the pain felt by the animal.
The treatment aims to cover 4 main aspects:
- Reaching and maintaining an ideal body weight;
- Physical rehabilitation and exercice;
- The animal's environment;
- Pharmacological therapy.
By losing weight, an overweight or obese animal will see the load carried by his joints diminish, which will decrease his discomfort and the progression of the damages to his joints.
On the other hand, by increasing his muscular mass, an animal that is too thin will be better able to bear his weight and, once again, decrease the articular load.
Furthermore, since muscles absorb chocs transmitted to joints, reinforcing the muscles might help protect the joints.
Therapeutic exercices are beneficial to an animal suffering from OA not only because they help him reach his ideal body weight, but also because they improve the joints mobility and decrease the inflammation.
Also, moderate weight bearing exercices stimulate the production of cartilage and the diffusion of nutrients to the joints, and can even increase the production of endorphins which are natural pain killers.
Exercice programs should be personnalized and adapted to each animal's condition and preferences. Indeed, an inadequate program can worsen the state of the joints and speed up their deterioration.
It is important to be constant with the amount of exercices that is asked of the dog. For example, it is best to avoid him doing a lot of exercices on the weekends and just a few exercices during the week.
Furthermore, it is preferable that the dog exercice often but for short periods of time instead of sporadically and for long periods of time.
Additionally, strong impact exercices, like running on asphalt or games that require abrupt starts and stops, must be avoided.
Finally, a dog that is in a period of intense pain shouldn't be forced to exercice or to play with other dogs, as he might get hurt or the inflammation in his joints might worsen.
In the case of an animal suffering from moderate to severe OA, it is beneficial to modify his environment.
First, if he lives outside, he should be brought inside because the humidity and the cold worsen the symptoms of OA.
It is important to provide a soft bed to rest and a heating blanket, placed underneath him and under an ordinary blanket (to prevent burns), to decrease the morning stiffness.
To minimize the risk of falling on slippery floors, we can put boots on his paws or change the surface of the floor covering.
For the same reason, it is also advisable to avoid stairs.
To slow down the progression of OA and to minimize its long term effects, it is important to identify and correct, if possible, the underlying cause when there is one.
With time, periods of aggravation alternate with periods of improvement. As mentioned before, dogs must not be forced to exercice during periods of aggravation of OA.
It must be remembered that since OA is a degenerative, progressive and irreversible condition, the treatment must be maintained for the remaining duration of the animal's life. If rehabilitation is interrupted, then all the progress made will be lost.
Here are some symptoms frequently seen in an animal suffering from osteoarthritis.
Have difficulty standing or sitting up;
Spend more time lying down or resting;
Present stiffness after an exercice;
Be reluctant to exercice as long as before;
Have difficulty climbing the stairs, on sofas or in the car;
Have difficulty jumping, running or walking;
Change his posture (his back might be arched or curved, his head kept lower than usual, his ears might be drooping, etc.);
Be less hungry or interested in his food;
Become agressive or be tense when touched;
Hide when he didn't use to;
Lose interest in his toys or in playing;
Not greet his owner with enthousiasm when he comes home;
Squat to pee instead of lifting his leg (if the dog is a male);
Tremble when squatting to do her business (if the dog is a female).
The first change that occurs is a loss of proteoglycan, a molecule that is part of the composition of the articular cartilage, which speeds up its destruction and slows down its regeneration.
After that, the articular capsule (a thick fibrous sheath encircling and protecting the joint) becomes thin and the composition and quantity of synovial liquid (liquid present in the joint that lubrifies and nourishes it) change.
In response to all those changes, the bone that is located beneath the cartilage remodels itself inappropriately. Osteophytes then appear (bony prominences) on the edges of the joints which, in turn, perpetuate the changes in the joints.
A vicious cycle of pain and loss of articular function and protection then ensues. With time, the range of motion of the joints diminishes.
The changes are then irreversible.
Pharmacological therapy includes, mainly, anti-inflammatories and neutraceuticals.
Anti-inflammatories are indispensable during acute periods of pain.
Although the exact mecanism of action of neutraceuticals is unknown, clinical trials have demonstrated that most of them seem to help animals suffering from OA. They are not medication per se, but should be considered nutrients that support the normal structure of joints.
They should not be used alone to treat OA.