TL;DR: Hind leg skipping in cats is typically caused by a luxating patella, which is not an immediate emergency but requires a veterinary evaluation to prevent long-term joint damage.
What causes my cat to skip or hop on their hind legs?
When a cat 'skips' or intermittently hops while walking, it is most commonly associated with a condition called a Luxating Patella. This occurs when the kneecap (patella) temporarily slides out of its natural groove. As the cat walks, the kneecap pops out of place, causing the leg to lock or skip, and then pops back in, allowing the cat to resume a normal gait. While it looks unusual, it is often a mechanical issue rather than a sudden injury.
Is my cat skipping a step a medical emergency?
- Urgency Level: Low. In most cases, a cat skipping a step is not an immediate medical emergency, especially if they are still eating, drinking, and behaving normally.
- Skipping indicates an underlying joint issue that can lead to long-term arthritis or ligament damage.
- You should schedule a routine veterinary appointment within the next few days to have the joint evaluated and to discuss management options.
How can a photo or video help my vet diagnose the skipping behavior?
- Capturing the behavior at home is vital because cats often hide pain and may walk normally at the clinic due to adrenaline.
- A video of your cat walking allows your veterinarian to visualize the frequency and severity of the skipping in action.
- Clear photos of your cat's standing posture can help the vet identify subtle swelling or muscle wasting that might not be obvious during a quick physical exam.
Clinical Context (Merck Veterinary Manual)
Lameness in cats, presenting as skipping a step with a back leg, can stem from various causes, including fibrotic myopathy of the semitendinosus muscle or restrictions from annular ligaments, adhesions, or severe fibrosis. It is critical to correctly determine the cause of lameness, as treatment varies greatly. In fibrotic myopathy, a mechanical lameness, the affected limb is pulled back and down quickly before the end of the protraction phase, giving the impression that the foot "slaps down" on the ground, most obvious at the walk. Arterial thromboembolism should also be considered, where the cat can often move the legs above the stifles, and the tail is commonly unaffected; in some cats, only one hindlimb is affected. Diagnosis of arterial thromboembolism is based on clinical signs, physical examination findings, and Doppler blood flow readings of the hindlimbs, with ultrasound potentially identifying the thromboembolus.
Chapter: Neurology, Orthopedics
Source: The Merck Veterinary Manual, 11th Edition (Page 1096)