Osteoarthritis in cats and dogs

In the UK, around 10 million people suffer from arthritis. Did you know that animals get arthritis too? Here we will explain what arthritis is, what signs it causes, and how we diagnose

What is arthritis?

Osteoarthritis, often shortened to arthritis or OA, is a degenerative disease of the joints. The exact science of the disease is complex, and we are still finding more out all the time. Here’s what we know currently: Inside a joint, the ends of bones are capped by cartilage, a flexible tissue that protects the bones, reduces friction and provides shock absorption. Osteoarthritis starts when the balance between cartilage production and cartilage breakdown is disrupted. The cartilage starts to degrade and releases pro-inflammatory chemicals, which increase the rate of cartilage degradation. The cartilage softens, cracks and eventually wears away, exposing the bone underneath. Unprotected by cartilage, the bones will degrade too, with some parts of the bones eroding (sclerosis) and others forming new bone (osteophytes). Arthritis will also damage other parts of the joint too.

What causes arthritis?

There are many things which contribute to an animal developing osteoarthritis, and individual pets will often have multiple factors causing their arthritis.

Genetics

It is likely that there are genetics that affect the progression of arthritis, including those that affect collagen quality (collagen is a key component of cartilage), the immune system, growth and development. If any numbers of these genes are active, deactivated or missing, arthritis is more likely to develop. This means arthritis can be an inherited disease, and pets with severe arthritis should not be bred from.

As a result of their genetics, some pets are also born with skeletal abnormalities which predispose to joint disease and arthritis. These include elbow dysplasia, hip dysplasia and spinal malformations. Pets with these diseases tend to develop arthritis earlier than other animals and are prone to other problems in the joints, like ligament rupture. These are also inherited conditions that can be passed on to offspring. Any limb injuries in earlier life, like cruciate disease or broken bones can also lead to arthritis.

Breed

We know that some breeds of dog and cat are more prone to arthritis than others. Large-breed dogs, like Rottweilers, Golden Retrievers and Labradors, are more likely to develop arthritis than smaller dogs. Partly because they are heavier and thus more strain is put on the joints, and also because they are more prone to elbow and hip dysplasia. However, some conditions that can lead to arthritis are more common in smaller dogs, such as patella luxation in Pomeranians, Yorkshire terriers and French bulldogs. In cats, Maine Coons are prone to arthritis, again partly due to their large size, while others like Scottish Folds and Persians can develop arthritis as they can have cartilage disorders.

Obesity

Regardless of breed, overweight animals are more likely to develop arthritis. This is partly because they are carrying more weight that will put strain on the joints, but also because obesity increases pro-inflammatory chemicals in the body that degrade the joints. Obesity also increases the risk of conditions that then cause arthritis, like cruciate disease. Diet generally plays a part too, and studies have found that dogs with unrestricted diets when they are growing are more likely to develop joint disorders and arthritis later in life – keeping a dog lean reduces this risk.

Neutering Status

Multiple studies have shown that neutered dogs are more likely to develop arthritis, though it is unclear why. Partly, this may be because neutered dogs tend to live longer, thus are more likely to develop arthritis when compared to non-neutered dogs that may die earlier. It may also be linked to the tendency for neutered dogs to gain weight if not monitored closely, which can lead to obesity and arthritis as explained above. Neutered cats can also gain weight, so may also be more prone to arthritis in the same way. Neutering is generally a net-positive for most pets, but care must be taken to mitigate for arthritis.

There are likely to be many other factors that predispose a pet to arthritis, but these are the main causes owners should be aware of. Some are difficult to avoid, like genetic factors, while others can be prevented, like obesity and dietary-related.

What are the symptoms of arthritis?

There are many symptoms of arthritis. By far the most significant is pain. As the cartilage erodes, inflammation builds and the bones rub, pain signals are created. This can lead to a variety of symptoms including stiffness, lameness or reduced mobility, reduced interest in exercise, lethargy and associated weight loss, alternatively weight gain in some animals, grumpiness and other behavioural changes, difficulties toileting or accidents in the house, and loss of muscle mass over the painful areas. Cats and rabbits in particular struggle to groom themselves, leading to messy and matted back ends. In rabbits, this can mean they are unable to feed on their caecotrope poos, leading to malnutrition.

Physical inflexibility of the joints can also lead to lameness and muscle wasting. Whatever the cause, as the muscles waste away, the animal finds it harder to stand, the muscles continue to waste and often more weight is gained, creating a vicious circle. This immobility can lead to pressure sores, urine and faecal scalding if they become incontinent, and an inability to feed or drink. At this stage, there is often little that can be done to restore the animal’s comfort.

How do vets diagnose arthritis?

To diagnose arthritis, a vet will first want to ask the history of the animal – what makes you worry they are arthritic? What has changed? What symptoms have you noted? Though some early arthritic changes can be subtle and not noted by an owner, often you will have noted something is not quite right.

From here, your vet will want to examine your pet thoroughly. They will perform a basic exam, checking their eyes, ears, nose, heart, and so on, and then examine your pet’s musculoskeletal system. They will likely want to see your dog walk, to identify any lameness, then palpate the joints and bones. This can identify points of pain, stiffness, crepitus (joints rubbing) and other associated symptoms.

When a pet’s age, history and physical exam is taken into account, many vets will be able to presumptively diagnose osteoarthritis with this information alone. Though other diseases, such as acute injuries, neurological disease or even cancer can present similarly to osteoarthritis, treatment can often begin at this stage.

If the vet is unsure, or you are quite keen for a formal diagnosis, then imaging may be recommended. Radiography (x-ray) is a good starting point, as this will show changes to the bones such as enlargement of the joint space, inflammatory fluid, osteophytes, sclerosis, and other changes. Some early arthritis may not have significant radiographic changes, however, as cartilage does not show up on radiograph very well, so subtle degeneration can be missed. The other limitation of radiography is that it is 2D, so some changes can be masked by overlying bones. In these cases, advanced CT scanning (a 3D x-ray) can provide better assessment of subtle changes, or in difficult areas like the elbow. Ultrasonography, MRI or arthroscopy (cameras placed into the joint) can be useful in some cases too.

Finally, if underlying disease is suspected, your vet may recommend blood testing. Certain inflammatory conditions can predispose a pet to arthritis, and many older dogs with arthritis suffer from other diseases too, like liver or kidney disease. Identifying these is important for management of arthritis, and having an idea of the overall health of the animal will identify which medications are most suited for that animal.

How is arthritis treated or managed?

Unfortunately, arthritis cannot be cured and will progress over time. This means that the mainstay of treatment for arthritis is pain relief and management.

Drug Therapy

There are many different drug options for pain relief for arthritis. One of the most common classes of drugs are non-steroidal anti-inflammatories (NSAIDs) like meloxicam, carprofen and robenacoxib. These reduce inflammation within the joints and are often the first drug of choice for managing arthritic pain. However, they can put strain on the body over time, and are not always suitable for any animals with underlying liver or kidney disease. Vets normally recommend regular blood testing to monitor these organs.

As second-line pain relief, drugs like paracetamol (dogs only), tramadol (dogs only) and gabapentin are often recommended. These often work best alongside NSAIDs, though can be used alone. They too carry side effects, in particular drowsiness at higher doses of tramadol or gabapentin. Care must also be taken in patients with underlying health issues.

A relatively new class of drugs for arthritis are monoclonal antibodies, such as bedinvetmab or frunevetmab. These advanced drugs work by preventing pain chemicals produced in the joints being taken up by the body. Because they are made up of antibodies, and work in a similar way to vaccines, they are considered the safest option for animals with underlying health conditions like liver or kidney disease. These drugs are administered via subcutaneous injection by a vet, on a monthly basis, and are currently available for cats and dogs.

Some vets will also administer other drugs for pain relief, such as regular subcutaneous ketamine injections, intra-joint steroid injections or oral buprenorphine. These are less common but may be an option for some pets with arthritis.

Weight Management and Exercise

As discussed , obesity can increase the risk of developing arthritis, while being arthritic increases the likelihood a pet will develop (or worsen) . This makes weight management critical in breaking this cycle – every kilo lost is less strain on the joints. Generally, diets are recommended for pets who are overweight, which might be as simple as reducing their portion size, or it may require prescription weight loss food. Weight loss should be gradual, especially in cats and rabbits. Many vets hold weight loss clinics to encourage weight loss in pets.

Many pets do not want to exercise due to pain, so pain relief is always recommended first to enhance mobility. Once your pet is more mobile, keep exercise gentle but consistent. Short but more frequent walks are best for dogs. Try to avoid excessive running, jumping or twisting motions that can aggravate joints. Using ramps, steps or picking your animal up can help prevent unwanted movement. Swimming is a great low-impact exercise for dogs (or cats!) that like water.

You may even want to consider taking your pet to a specialist physio- or hydrotherapy centre . Here, specific points of weakness can be identified, and an exercise plan can be made to help the muscles slowly build up to improve your pet’s mobility. When combined with regular vet visits, the muscle wasting associated with arthritis can be stopped or even reversed.

Joint Supplements

There are many supplements and diets that can support joint health. These often contain chondroitin, green lipped mussel, glucosamine, or vitamin D. When used alongside pain relief, or alone for pets at-risk of arthritis, they can help slow down degeneration in the joints. However, they rarely provide actual pain relief and should not be used as a replacement for more effective treatments.

Other Therapies

Some vets may recommend alternative, or adjunctive treatments. Like joint supplements, these are best used alongside traditional medication, or as a last resort when pain relief has failed. These include laser therapy, acupuncture, massage, and stem cell therapy. Some of these treatments have limited evidence for their efficacy, so results can vary. Speak to your vet if you are considering these options.

Regular Check-Ups

Our vets will want to review your pet’s disease regularly to determine if they are comfortable enough, if their weight is being controlled, if their arthritis is progressing, check for any side-effects of the drugs, and how you as the owner are managing the disease. These visits are important, and you should try and attend as many as you can. How often these occur is dependent on the individual patient and vet, but every 3-6 months for a pet with stable arthritis is common.

Surgery

In some cases of arthritis caused by underlying disease, treating the primary disease with surgery can help reduce the progression of arthritis. An example would be the various surgeries for cranial cruciate disease. There are even sometimes advanced surgical options for the treatment of primary arthritis, such as femoral head and neck removal in the hip, arthrodesis (surgical fusion) in places like the wrist, or complete joint replacement surgeries. These surgeries require specialist orthopaedic surgeons, and may not be suitable for your individual animal, especially if they are older, overweight or have advanced arthritis.

Euthanasia

Sadly, whatever we do, in most cases arthritis will progress to the point where pain cannot be controlled, the animal can no longer stand or do normal activities, or they just aren’t happy anymore. In these cases, once treatment has been exhausted, often the kindest option is to consider saying goodbye to your pet. Though this is a difficult decision to make, it can be the right thing to do to prevent suffering. You can talk to us about when the right time might be to say goodbye to your arthritic pet, and we can help you to decide or plan.