Carpal Hyperextension

This joint supports a dog's weight and facilitates various movements. The carpus (front wrist joint) comprises of seven small bones. Ligaments on both the front and back of the wrist stabilise these bones.

As a result, the ligaments can no longer support the wrist joint structure in place. Carpal hyperextension in dogs - also known as dog carpal hyperextension / carpal laxity - is a condition that affects the carpal joint. 

These are the medial collateral, the palmar radiocarpal and the palmar ulnocarpal ligaments. When healthy, these ligaments hold the wrist joint in the correct position and at a normal angle. 

If there’s ligament damage, you’ll see an increased extension of your dog’s wrist joint. The joint drops much closer to the ground than normal. You may even notice the joint, or carpal pad, touching the floor.

You might have noticed your dogs wrists or carpal joint getting closer to the ground. It is possible they have carpal hyperextension. The most common signs of carpal hyperextension are:

• Limping in the front legs - or maybe favouring one leg in particular
• May display an unusual gait - an unusual hopping or rolling motion
• An affected puppy may have a gait more like a bear’s than a dog’s 
• The carpus (wrist) dropping towards the ground - it looks noticeably bent
• The standing angle of the joint - normally 140°-180° in dogs - reduces to as little as 90° (an abnormally flattened position)
• The wrist or carpal area can feel floppy
• As the condition progresses, the standing angle of the joint can gradually decrease further
• The development of dog carpal joint swelling and pain
• When viewed in profile, a dog with normal carpus will have straight legs and only a ‘small’ paw on the ground. When viewed in profile, a dog with carpal hyperextension will have a flat-footed ‘duck’ look.
• Your dog doesn’t want to go on longer walks anymore - even short walks or exercise may be a struggle
• Your dog may be reluctant to put weight on the affected limb
• There may be pressure sores or ulcers on the carpal pad where it’s rubbing against the floor

Your dog's carpal extension must be assessed by your vet or an orthopaedic specialist to determine the underlying cause. Sometimes it’s possible to diagnose through visual examination only. Your vet will likely do a thorough physical examination to also check for bone abnormalities in other joints.

For a clear diagnosis, it might be necessary for assessment under sedatives/anaesthesia. Diagnostic imaging, such as X-rays, CT scans or an MRI, follows.

An X-ray will show nothing wrong with the carpal bones and rule out medical conditions.

An MRI scan will show the ligaments have torn and lengthened.

Once the reason for carpal hyperextension in your dog is established, you can choose the appropriate strategy for your dog's condition.

There are various explanations for why your dog has got carpal hyperextension.

• Dog wrist injury - the most straightforward cause. Your dog has somehow sustained or traumatised their wrist joint. Maybe your dog jumped off something too high. This put excessive force on the carpal ligament and bent it beyond normal limits. The ligaments tore, and stability was lost.

• Developmental or congenital abnormalities in puppies (typically younger than 4 months) - particularly large breeds - can cause carpal hyperextension (e.g.Carpal Laxity Syndrome). These puppies don’t have normal strength in their ligaments. Laxity means loosening, therefore the wrist joint is loosening.

Sometimes this happens because your puppy’s experiencing a growth spurt. Their food isn’t giving them everything that they need nutritionally to keep up. Other times it might be because your puppy's worn a cast or bandage over a period of time. If that’s the case, only that specific joint is affected. 

At other times, the condition is idiopathic. In these cases, both puppy's front limbs will be affected for no apparent reason.

• Ageing - degenerative changes can happen over time through wear and tear in older dogs. Collie dogs seem particularly vulnerable to these changes. As a dog ages, the ligaments degenerate, stretching and weakening. The carpus starts hyperextending, and the joint isn’t held properly. Other joints, such as the hock, may also be affected similarly. Sometimes the degeneration is a symptom of an immune-mediated joint disease. However, this is relatively rare.

Degenerative conditions are more likely in older dogs than in other age ranges. 

• Genetic predisposition - Male puppies are most at risk. Some breeds (large and giant breed, possibly dobermans and shar-peis) appear over-represented. Collies seem disproportionately affected by age-related degeneration.

Your vet will advise on the best way forward. Identifying the signs of carpal hyperextension in dogs is crucial for early intervention. Diagnosis may involve a thorough physical examination, X-rays, and possibly other imaging studies to assess the extent of joint and ligament damage.

Can I do anything to prevent my dog from developing carpal hyperextension?

Some factors leading to carpal hyperextension are beyond our control. However, there are steps you can take to minimise the risk:

• Regular exercise - maintain your dog at a healthy weight. Ensuring your dog gets regular, controlled exercise can contribute to overall joint health
• Consider adding a joint health supplement to your dog’s diet
• Avoiding traumas - supervise your dog to prevent accidents. Do what you can to lessen the risk of falls, collisions or jumping off from high surfaces
• Genetic screening - consider genetic screening, if you have a breed predisposed to joint issues. Consult with your veterinarian on preventative measures.

What breeds commonly get carpal hyperextension?

Collies seem vulnerable to age-related carpal hyperextension. Shar-pei and Doberman puppies may be more at risk to the developmental varieties.

What age does dog carpal hyperextension start?

Carpal hyperextension can happen to a dog at any age, particularly if it’s caused by an injury or trauma to the carpus (wrist). However, young puppies are more vulnerable to congenital or developmental abnormalities. Older dogs, on the other hand, are prone to degeneration. (See above).

Diagnosis may involve a thorough physical examination, X-rays, and possibly other imaging studies to assess the extent of joint damage.

How can I help my dog?

Reduce your dog’s activity until you’ve formulated a treatment plan. Not all dogs will show signs of being in pain. However, If your dog looks in pain, ask the vet about pain relief or explore pain-relief supplements.

Treatment Options: Is there a treatment?

Unfortunately, the palmar ligaments don’t tend to heal well. Your treatment will be determined by the severity of the condition, your dog’s age and the likelihood of the ligaments repairing themselves.

• Non-surgical management - rest, weight control, restricted activity and physiotherapy might help in mild cases. Your vet may prescribe NSAIDs, although it’s reported that they’re seldom helpful in relieving symptoms. In non-chronic, mild to moderate cases, long-acting corticosteroid injections into the area of the tendon sheath can make a difference.

• Physical therapy - Rehabilitation exercises might help strengthen the muscles surrounding the carpal joint, providing additional support. This approach, in combination with pain medication, is often recommended for dogs with age-related ligament deterioration.

• Conservative management - splints and support dressings can provide stability and promote healing. Generally, these are short-term solutions. They don’t help the ligaments to repair. Sometimes splints in puppies are recommended, but at other times, they can be contraindicated and worsen the condition. Get advice from your vet.

• Medical - in the rare instance of carpal hyperextension being a symptom of diagnosed immune-mediated polyarthritis, medication will probably be prescribed. Surgery might also be recommended in severe cases.

• Surgical Intervention - Severe, high-grade sprain injuries and many forms of degenerative hyperextension may require surgical correction to stabilise the carpal joint and address the underlying issue. 

Surgery is often the preferred treatment because of the unlikelihood of the ligaments healing through conservative treatment. There aren’t any procedures to restore the dog carpal joint, so arthrodesis surgery (fusing the joint) is often recommended. 

The veterinarian surgeon uses a combination of plates and screws to fuse the forelimb with the paw across the carpal joint. This immobilises the carpus in a functional position. 

The surgery allows your dog to weight bear normally and provides stability. It won’t, however, restore the joint’s previous mobility.

There are two main types of carpal arthrodesis surgery:

Partial Carpal Arthrodesis: There are 3 rows of carpal joints. If the two with minimal movement - the middle carpal and carpometacarpal joints (either or both) - are affected, they can be fused together. This is intended to preserve the movement of the joint. The risks of this surgery include the possible development of osteoarthritis or collapse of the main joint - the antebrachiocarpal. More surgery may then be necessary. There have been improvements in the implants used for partial carpal arthrodesis. Post-surgery, this may help maintain the joint for longer.

Pan Carpal Arthrodesis: When the antebrachiocarpal joint is damaged, this surgery fuses the entire carpus joint. It’s recommended as the carpus is likely beyond repair. The surgery allows your dog to use the limb again. Post-surgery, there’s also often a significant reduction in pain. A bone plate (sometimes two, plus screws) stabilises the carpus. Sometimes bone taken from the shoulder is grafted to the arthrodesis site to improve the chances of a successful outcome. This surgery allows dogs to have normal or near-normal function after the surgery. However, their gait will be permanently altered.

As with all surgery, there’s the possibility of complications - some of which may need further surgical management. Therefore, rigorous post-operative care is very important. This will help to minimise the risk of these complications occurring.

Post-operative care includes

• Wearing a splint for 6 to 8 weeks after surgery to provide additional stability to the carpal joint. The plate needs extra support as it’s not yet ready to support your dog’s full weight. 
• The splinted area will have to be monitored to check for rub spots. It will have to be kept clean and dry i.e. no swimming or grooming for 2 months
• According to the vet's post-operative care plan, there is a significant reduction in your dog’s activity levels. If your dog exercises as normal straightaway, the surgery will likely be a failure.
• Regular vet check-ups to keep an eye on healing and progress
• Generally, normal activities can be resumed after 12 weeks. Again, your vet will advise you on this.

Help around the house

Ensure your dog has a comfortable place to rest and sleep. Consider a ramp so your dog doesn’t have to jump on and off beds or sofas. A front lift harness can help you reduce the load on your dog’s forelimbs when walking or getting up and down stairs, into the car etc. Neoprene carpal support wraps around the house and gives light to moderate support to the ligaments and muscles. It’s also a good idea to ensure your dog has as much grip on the bottom of their paw as possible. This reduces the chance of further injury to the wrist caused by slipping on wooden or smooth floors. Socks with a rubber base, such as the Traction Socks, improve grip.  

Conclusion

Carpal hyperextension in dogs can be a challenging condition. Early detection and appropriate intervention can significantly improve outcomes. If you see signs of discomfort or changes in your dog's gait, consult a veterinarian promptly. By understanding the causes, symptoms, and treatment options, you can play a crucial role in ensuring the well-being of your dog with carpal hyperextension.