Osteoarthritis in Dogs
Arthritis is a condition causing pain, inflammation and stiffness of the joints. When people talk about Arthritis they are usually referring to Osteoarthritis, the most common type. Other types of Arthritis can occur less commonly in our pets, such as Septic Arthritis due to infection, or Immune-Mediated Arthritis.
Often referred to as OA, or Degenerative Joint Disease (DJD), Osteoarthritis is a progressive condition and the most common cause of chronic pain in our pets. Any pet can be affected by Arthritis, including dogs, cats and rabbits. Some breeds are more likely to be affected, especially those with a predisposition to joint disease, such as Labradors. Any age pet can be affected, though it is more common in older animals. It is estimated that by eight years of age, four out of five dogs will be suffering from Arthritis in one or more joints.
Underlying causes include poorly formed joints (such as in elbow or hip dysplasia), trauma, instability (such as with Cruciate Disease or Patella Luxation) or other joint conditions. Once OA develops, cartilage that lines the joints becomes damaged and is not repaired or replaced. Damaged cartilage can no longer create thick, viscous joint fluid that helps to provide shock absorption. The entire joint becomes inflamed, and lack of cushioning from joint fluid and cartilage makes everything weaker and less stable. In response, scar tissue may form making the joint stiff and unable to move normally. Eventually new bone is deposited around the joint, which is visible on x-rays.
During this degenerative process, inflammation triggers nerve receptors in the joint to send regular signals to the brain to say something hurts. As Arthritis progresses, more nerve receptors are created, and they send signals more often. This phenomenon is called “wind up” and means the brain will receive a disproportionate amount of pain signals in chronic conditions than would be caused by a short-term inflammation of a similar level. A key part of management of OA is trying to prevent or reduce “wind up”.
Symptoms of Arthritis can, therefore, be subtle, but include:
- Lameness
- Unwillingness to walk/reduced enthusiasm
- Reluctance to climb or descend stairs
- Difficulty getting comfortable
- Sleeping more than usual
- Changes in temperament or behaviour
- Seeming lethargic or depressed
- Licking the joints
- Pacing at night
- Weakness of the hind-limbs
- Difficulty toileting
- Changes to posture or appearance
Arthritis can be considered very likely based on a history of compatible symptoms and a clinical examination by a vet. Some dogs have a known predisposition, such as Hip Dysplasia or a history of joint surgery. In affected dogs, the joints may be stiff, sore or swollen on examination.
Imaging, such as radiography (x-rays) or CT, is the ideal method of diagnosis as this allows changes in the joint to be directly assessed. Occasionally, a sample of fluid is removed from the joints for analysis (called a “joint tap”). Sometimes anaesthesia is not advisable due to other health problems, so an assumed diagnosis is made based on consistent symptoms. In these cases, a positive response to treatment can also help confirm the diagnosis.
Clinical Metrology Scoring is a validated system to grade a pet’s lameness in an objective and repeatable way. It can be used in an initial assessment to determine the degree of lameness present and therefore the most appropriate treatment plan, or to monitor response to treatment. The Liverpool Osteoarthritis in Dogs (LOAD) questionnaire is a reliable and repeatable way to identify if a dog has signs of joint disease and consists of 23 simple questions you can answer at home.
Older pets are prone to many other problems that can cause them to “slow down”, so it is important to rule these out before assuming a diagnosis of OA, especially where symptoms are more vague or non-specific.
Management at home
Weight management
Home adaptations
Exercise modulation
Complementary therapies
Nutraceuticals
Medical management
Most pets with Arthritis will benefit from some degree of medical management. This may include pain relief, anti-inflammatories, joint modulation or even surgery.
For some pets, a short course of medication may be suitable to reduce “wind-up" and allow the benefits to be felt from other changes, such as weight loss or physiotherapy. For other pets, medical management is likely to be required long-term. It is likely that your vet will want to review your pet at regular intervals to ensure any medications are still necessary and suitable.
It is important to remember that no medication is entirely without side effects. Our goal is to balance the impact of drug use against the benefits to the pet, especially in alleviating their discomfort and the impact this has on their welfare.
Commonly used medical treatments include:
Non-steroidal anti-inflammatory drugs (NSAIDs)
E.g. Meloxicam (Meloxaid, Metacam®), Carprofen (Rimadyl, Carprieve), Robenacoxib (Onsior®)
These drugs are highly effective at controlling pain and inflammation, and are usually the first medication prescribed for OA. NSAIDs can be used as a short- or long-term treatment and are suitable to be used after surgery. They come in different formats, such as tablets or liquid, and usually need to be given daily. Most NSAIDs can be easily adjusted to trial a lower dose if your vet feels this is appropriate.
The most common side-effect from NSAIDs is gastrointestinal upset (vomiting or diarrhoea) which stops when medication is withheld. Rarely, this can progress to gastrointestinal ulceration, bloody diarrhoea, or kidney damage. NSAIDs are metabolised by the liver or kidneys, so pets needing long-term NSAID therapy should have blood tests performed every 6-12 months to ensure there are no underlying problems that mean the drugs are no longer suitable.
Other Anti-inflammatories
E.g. Paracetamol, Gabapentin, Amantadine
If a patient doesn’t suit NSAIDs, or these drugs alone are not sufficient to manage symptoms of OA, other drugs can be used instead or as well. Most of these drugs are human medications, not licensed for pets, and are prescribed under the veterinary cascade. The law states that your vet should recommend licensed medications first; for this reason, in most cases your vet will recommend trying NSAIDs first.
Monoclonal Antibody Therapy (mAb)
E.g. Bedinvetmab (Librela®, Beransa)
These drugs work by targeting nerve growth factor (NGF), which has the effect of reducing pain and inflammation in arthritic joints. They work specifically in Arthritis so are not used for pain elsewhere in the body, or for conditions such as Cruciate Rupture (prior to surgery) where Arthritis is not the primary problem.
MAb drugs are given by injection, and last for approximately a month, so are a good option for pets that do not take oral medication well. They are typically more expensive than NSAIDs, and pets will have to attend the practice monthly to receive the injection.
MAb therapy has some recognised side effects. The most common is an increase in thirst and urine production while on treatment; particularly in older animals this may have an impact on their ability to hold their bladder. Other uncommon side effects include vomiting, diarrhoea, reduced appetite and incoordination (known as ataxia).
A condition called Rapidly Progressive Osteoarthritis (RPOA) is a known side-effect in humans treated with mAb therapy. In affected people, the condition of one or more joints worsens quickly and significantly after receiving mAbs and these changes are irreversible, even if treatment is stopped. Often, it leads to the need for invasive treatment, such as joint replacement.
RPOA is not currently known to occur in dogs. At the time of writing, there have been a number of veterinary cases reported in which similar changes to RPOA have been observed in dogs after mAb use. At the present time, this has not definitively been linked to mAbs, and affected dogs were often receiving other treatments at the same time. Research is being undertaken to better understand whether there is a direct link between mAbs and deterioration of Arthritis in dogs, and whether this should therefore be considered a possible side-effect of mAb use.
For many dogs living with Arthritis, mAbs offer a significant improvement in quality of life. It is recommended that mAb therapy is used following the manufacturer’s guidance, specifically it should only be used for pets with primary OA and should not be given at the same time as NSAIDs without careful consideration. Due to their effect on growth factors, mAbs should only be used in dogs over a year or age and must not be given to dogs used for breeding.
Regenerative medicine
Surgery
Most cases of Arthritis don’t benefit from surgery. If there is an underlying condition present, such as Cruciate Ligament Rupture, surgery may be recommended, and your vet will be able to advise if this is appropriate for your pet. Less commonly, salvage procedures are used to manage very severe Arthritis. These may include hip replacements or joint fusion, known as Arthrodesis.
There are a wide variety of treatment options available for OA, ultimately the choice of treatment should be based on what is best for you and your pet and guided by your vet. It is important to remember that what is right for one patient is not right for every patient.
For patients taking some medications long term, a written prescription can be requested from your vet enabling you to purchase medication from an online pharmacy.
