Carpal hyperextension: palmigrade in a cat

Why will a cat walk with hyperextended front limbs? Will carpal hyperextension be secondary to a neurological problem? Is palmigrade and plantigrade the same? Let’s get into all these questions

Carpal hyperextension is caused by damage to the ligaments that stabilize the carpus. In the cat the palmar ligaments and palmar carpal fibrocartilage maintain the normal degree of carpal extension. The collateral ligaments also have some function in maintaining the carpal extension.

In a mild case of carpal hyperextension, the ligaments may only be stretched or strained; in a severe case, the ligaments may be completely torn. A lack of carpal stability leads the carpus to sag towards the ground, or become hyperextended, when the cat is bearing weight.

Carpal hyperextension is NOT secondary to a neurological disease! This is very important to remember. Plantigrade posture COULD BE, for example in cats from a neuropathy, which is commonly secondary to diabetes but here we’re talking about Palmigrade, not plantigrade.

Carpal hyperextension in cats is typically caused by trauma. Although this condition occurs with some frequency in dogs, it is rare in cats and usually only occurs in association with a fall from a high location.

So what was the clinical presentation of this cat? WHAT CAN WE SEE ON THIS VIDEO?

You can see the left front limb that is knuckling, the cat is managing to put weight on it, but sometimes struggles to do the carpal extension and when he does it’s exaggerated.

However, you don’t see any ataxia and the rest of the limbs are completely normal. Why we know this is not neurological? First because when we do the neuro exam we find normal proprioception on all 4 limbs and we can also see a normal carpal extension reflex. I know you’ll be thinking neurological because of the knuckling

But remember that if this was neurological, you will not see that hyperextension, but just dragging all the time and lack of spinal reflexes.

Diagnosis: Although ligaments cannot be viewed on X-rays, taking “stressed views” (in which the carpus is manipulated into various positions) can aid in the diagnosis of ligament damage by assessing the stability of the joint. X-rays are also used to look for fractures of the small bones within the carpus.

Treatment is partial carpal  or pancarpal arthrodesis…but for that I leave it to my friends the orthopedists