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Cautionary Tale

Before panicking, get a diagnosis, says Neo-loving vet Robin White

It started with a limp. Then there was a firm, painful swelling on the inside of the left paw.  

I was terrified.  

In a 4-year-old giant-breed dog like my Aurelia, those signs are classic for the dreaded osteosarcoma, or bone cancer.  


The arrow points to the mild bony protrusion caused by inflammation and swelling of the tendon attached to the dewclaw. The darker gray swelling by the arrow can also be seen, and corresponds to the firm soft-tissue swelling at the level of the wrist.


Bone cancer is commonly seen in older large- and giant-breed dogs; it can start as a limp, and usually is accompanied by a firm, painful swelling. Common sites for osteosarcoma in the dog include the distal femur, proximal tibia (large bones of the knee joint), the proximal humerus and the distal radius. My girl had swelling in the area of the proximal radius – the upper portion of her wrist.  

After putting Aurelia on some pain medication and a few days of observation, I bit the bullet and took radiographs. Instead of the moth-eaten, boney appearance commonly seen with osteosarcoma, what I saw was a pleasant surprise – and a good reminder that a full veterinary workup is the best place to start with any health issue.  

On close examination of the radiographs, I diagnosed my girl with tenosynovitis of the abductor pollicis longus muscle; essentially, she had inflamed the small muscle associated with her dewclaw (thumb), which in dogs is used to help stabilize the wrist. (De Quervain’s tenosynovitis is a similar condition in people.) While not common in dogs, when it is seen it usually involves large-breed dogs, often secondary to significant amounts of exercise, although the repetitive jumpers and pacers are also at risk. I suspect Aurelia got it from all the hiking we had done recently.   Treatments described for this condition vary from simple rest and pain meds to steroid injections and even surgery. Many articles commented on how the boney changes and mild swelling can be permanent.  

My girl just got extra rest and a reprieve from any future long hikes. Within a few months, the limp was gone, although a minor swelling still remains.   That was a hugely better prognosis and outcome than if it had been osteosarcoma. And it was a good reminder for me of the importance of following through and finding a definitive diagnosis for every limp – especially when my imagination fears the worst.  


Robin White, DVM, is a veterinarian and breeder of Neapolitan Mastiffs under the kennel name BluHouse Mastini. Robin is pictured here with her home-bred female, Aurelia, who at 5 is still going strong, although she now goes at a more leisurely pace.   


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