by Cheryl Smith, DVM
Arthritis in the simplest terms means the condition of inflammation of the joints. Any species of animal with an endoskeleton has the potential to develop or have arthritis. When most people are talking about arthritis in dogs and cats, they are usually talking about older animals with wear and tear issues, or after specific joint injury. To understand better, let’s talk a bit about different forms of arthritis and their causes.
If a joint between two bones develops a bacterial infection, this is called septic arthritis. This can affect one joint (penetrating injury through joint capsule) or multiple joints (through systemic infection). As one might imagine, this is an acute situation and very painful. Prompt identification and treatment can minimize long term problems, but often sets up those joints for problems in the future if the individual survives the illness resulting in the sepsis in the first place.
There are also immune mediated conditions that can result in hot, swollen, painful joints. Again, getting the inflammation under control is needed to minimize long term problems regarding the joint(s).
Trauma and resultant arthritis/degenerative joint disease
Any trauma that disrupts the normal anatomical structure of the joint, leading to a loss of stability, will result in arthritis. Incorrect anatomical alignment and laxity can both contribute to inappropriate movement which can then put a strain on the joint capsule and remaining ligament and tendon structures. This is what leads to chronic and persistent arthritis and resultant degenerative joint disease.
This type of trauma can happen because of an “accident” (e.g. blunt trauma, lower limb caught in something which torques the joint to point of trauma) or repetitive movements past the point of what that animal’s structure can handle.
And again, anything that results in joint instability and improper movement of the joint will result in tissue inflammation and arthritis.
Conformation of the individual animal has a lot to do with the development of degenerative joint disease. A dog with “perfect” conformation would be able to do the activities it was bred to do well into old age if no trauma occurred. Unfortunately, that is not normally the case. Dogs with good conformation and really good luck, do work well into old age with little problem.
Examples of this are the sled dogs running the Iditarod. Many run well past 8 and 9 years of age because they are expertly conditioned, fed and trained and monitored. Nearly the opposite is true of our overfed, under exercised, under conditioned pets that try to do the “weekend warrior” method of play and often present with acute joint strain, sprain or traumas.
The occurrence of cranial cruciate ligament disease in pet dogs across this country is of epidemic proportions. In this veterinarian’s opinion, there are many factors contributing to this epidemic. Number one is being over weight and under conditioned; other factors are lack of selection for structure and temperament for activity desired.
If a joint has sustained an injury that is repairable, the goal of repair is to return as close to pre-trauma anatomy as possible, with the joint function as close as possible to normal range. This presents many challenges depending on location and severity of injury, which means there will likely be some degree of laxity, inflammation, and over time, degenerative changes.
Congenital conditions leading to arthritis
Animals that have abnormal joint anatomy are on a pretty straight course to arthritis. Common conditions include luxating patella, hip dysplasia, chondrodysplasia, ununited aconeal process, elbow dysplasia and OCD (osteochondritis dissecans). All these conditions mean there is abnormal anatomy and therefore abnormal function or stability of the joint involved.
Wear and tear/aging
Dogs and cats, even with decent conformation and condition, will like all of us, eventually use their joints to the point arthritis may develop. Which joints are most affected will be related to their activities. Just like people, a combination of predisposition and how they use their bodies will lead to having knee, hip, shoulder or back (spine) problems or some combination of those.
When dealing with wear and tear or after minor trauma, anti-inflammatory agents and nutriceuticals are available and used in veterinary medicine. Like all medications, there are the potential for side effects. Adjunct therapies like chiropractic manipulations, acupuncture and physical therapy can all be used to keep animals up and moving. All programs should be developed for individuals; there are no correct protocols to fit all.
The biggest contributor to our pets having arthritis to the point of needing daily medication and other expensive treatment is overfeeding. If you want to prevent arthritis, don’t let your pet be overweight; this will prevent a large portion of daily overstress to joints and their ligaments. If you want a minor accident to not result in real injury, don’t have your pet be overweight. A well conditioned athlete is less likely to get hurt during normal activity.