A veterinarian discusses three categories of causes of sudden hind leg weakness in a senior aged cat.

If your old cat has experienced sudden-onset weakness in its hind legs, there can be a serious medical cause for this.

Trauma As a Cause of Sudden Rear Limb Weakness in an Old Cat

Being hit by a car, falling from a height, or being accidentally struck or stepped upon can cause a senior cat’s back legs to suddenly become weak, says Dr. Jules Benson, BVSc, and VP of Veterinary Services at Petplan pet insurance.

“With appropriate veterinary treatment, sometimes full control can be returned, but the first 24 hours are critical,” says Dr. Benson.

If you suspect trauma, get your cat medical attention as soon as possible.

Saddle Thrombus Can Cause Sudden Back Leg Weakness in Older Cats

A thrombus is a blood clot, which can be common in cats with heart disease.

Dr. Benson explains, “A blood clot dislodges from somewhere in the body, then lodges at the pelvic end of the aorta where the blood vessels split to go down the legs (an area known as the saddle), resulting in lack of blood flow to the legs.”

The aorta is the largest blood vessel and begins at the heart, distributing blood throughout the body with each heartbeat.

The condition is called feline aortic thromboembolism, and it’s very painful with an often poor prognosis.

“Treatment is aimed at dissolving the clot and controlling pain,” says Dr. Benson.

“Cats with cardiac disease are usually prescribed an anti-clotting agent to reduce the chances of an embolism like this occurring.”

Infection May Cause Sudden Hind Leg Weakness in an Old Cat

Infectious disease can arise from a number of sources that affect the brain, including tick-borne diseases, Cryptococcus, feline infectious peritonitis and taxoplasmosis.

As you can see, cancer is not on the list of sudden rear leg weakness in an older cat.

However, this list is not complete; it represents only the more common causes.

“As with many conditions, the prognosis improves the earlier it is detected, so bring your cat to the vet at the very first sign of any hind limb weakness,” says Dr. Benson.

Dr. Benson is regularly consulted by many media outlets including ABC, NBC, FOX, The Wall Street Journal and The New York Times to provide pet health advice to pet parents nationwide.
Lorra Garrick has been covering medical, fitness and cybersecurity topics for many years, having written thousands of articles for print magazines and websites, including as a ghostwriter. She’s also a former ACE-certified personal trainer.  


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