Carpal Hyperextension in Dogs

For many owners, the first symptom noticed is an unusual gait or refusal to weight bear on a forelimb. As further trauma can cause complications it is vital you contact your veterinarian if you suspect your pet may be suffering from this condition. The prognosis without treatment is poor, however for pets who receive surgery there is a good chance of full limb function recovery.

Carpal hyperextension is caused by excessive force on the carpus, leading to the tearing of the ligaments and fibrocartilage and collapse of the carpal joint. This can be caused by sudden trauma such as falls or injury during exercise or chronic conditions such as abnormal posture while weight-bearing.

The symptoms will vary but may include: 

• Pain and swelling on the forelimb
• Abnormal, hyperextending stance and gait 
• Crying or pain vocalisation
• Increased distal limb extension
• Joint instability

• Acute traumatic - Caused by excessive force on the carpus, leading to the tearing of the ligaments and fibrocartilage and collapse of the carpal joint; this is common following a fall and injuries while working or exercising 
• Inflammatory polyarthropathy - Arthritis that causes the immune system to activate an inflammatory response in the joints causing swelling, pain and joint laxity 
• Degenerative - This form is common in some Collie breeds and often causes spontaneous, bilateral carpal joint hyperextension

Your veterinarian will perform a full clinical examination on your pet and watch your pet’s gait to assess weight bearing and source of pain. It is likely that your veterinarian will perform radiographs on your pet under sedation. In order to visualise the carpus and assess it for hyperextension a series of radiographs will be performed to demonstrate weight bearing positions. This will allow visualisation of the ligaments and damage.

The best treatment for your pet will depend on the underlying cause of the carpal hyperextension. 

Conservative Care

If your pet is suffering from developmental hyperextension or a low-grade sprain he may be able to utilise rest and exercise restriction. Your veterinarian will provide a supportive splint for your pet and may recommend physiotherapy and hydrotherapy.

Surgery

If your pet is suffering from a fracture he will require orthopedic surgery in order to stabilise the fracture. In some cases, a partial carpus fusion is required, where the middle and carpometacarpal joints are fused together to reduce movement without the antebrachial joint. In cases of severe injuries and degenerative hyperextension a procedure called pan-carpal arthrodesis may be required. This immobilizes the carpal joint by fusing all three of these joints together using internal fixation. Your veterinarian will be able to discuss this procedure with you when viewing your pet’s radiographs. 

A general anesthetic will be required for this procedure, although there are risks involved with anesthesia a qualified veterinary nurse will carefully monitor your pet’s vital signs throughout the surgery. In order to reduce the anesthesia agent needed, and therefore reduce the risk of respiratory and cardiac depression, a brachial plexus nerve block may be given to your pet prior to the surgery. 

Post-operative recovery

To provide pain relief following the surgery a non steroidal anti-inflammatory will be given to your pet. Your pet will be placed in a warm, dark area to recover from the surgery and offered food once he is alert. To support the limb, a Robert Jones dressing will be applied until the swelling reduces.

Provide your pet with a warm, enclosed area to recover in. Although your companion may have a reduced appetite, ensure food is offered. It is important during this healing period that your pet is given excellent nutrition; high fat foods such as anchovies provide palatability while protein, which has a restorative effect on damaged muscle and connective tissue, promotes healing.

The prognosis following surgery is good with 74% of patients regaining full limb function within 4 months. Your pet will be discharged with a coaptation cast that will be required for 6-8 weeks, it is important that this is kept clean and dry, as infection is one of the known complications of this procedure. 

One of the main causes of surgery failure is unprotected weight bearing. With this in mind, you may need to restrict your pet’s activity during this time; ensure movement restrictions are discussed with your veterinarian and a clear plan is in place. 

Following the surgery, radiographs will be taken at 6 - 8 weeks to assess the the procedure and visualise the fusion of the joint. If the surgery was successful implant removal at 12 -16 weeks may be recommended.