If your small dog suddenly hops or skips a step on a back leg, then trots on normally as if nothing happened, the most likely culprit is a luxating patella — a kneecap that slips out of its groove. It is one of the most common orthopedic problems in small and toy breeds, and many dogs are born with the tendency. Mild cases cause only an occasional skip and need no surgery, while more severe grades cause persistent lameness, pain, and early arthritis. Keeping your dog lean and catching the problem early are the most important things an owner can do.
Last reviewed: June 2026
What a Luxating Patella Is
The patella is the kneecap, a small bone that normally glides up and down in a groove at the end of the thigh bone as the knee bends. In a luxating patella, the kneecap pops out of that groove — usually toward the inside of the leg in small breeds. This happens when the groove is too shallow, the supporting structures are loose, or the alignment of the leg is off, conditions most dogs are born with. As described in Tobias & Johnston's Veterinary Surgery: Small Animal, patellar luxation is graded from one to four based on how easily and how often the kneecap dislocates, which guides treatment decisions.
The Grades, From Mild to Severe
Vets grade patellar luxation on a one-to-four scale. In grade one, the kneecap can be pushed out of place by hand but immediately pops back and rarely luxates on its own. In grade two, it luxates occasionally during activity and returns on its own or when the leg is straightened — this is the classic intermittent skipper. In grade three, the kneecap is out of place most of the time but can be manually replaced, and in grade four it is permanently dislocated and cannot be repositioned, causing significant lameness and altered limb conformation. The grade strongly influences whether a dog needs surgery and what its long-term outlook is.
The Signs Owners Notice
The hallmark sign is an intermittent skip or hop: the dog is trotting along, suddenly holds up a back leg for a stride or two or does a little bunny-hop, then carries on normally once the kneecap slides back into place. Some dogs stretch the leg backward to pop the kneecap in. Higher grades cause more constant lameness, a bow-legged or crouched stance, reluctance to jump, and signs of pain or stiffness, especially as secondary arthritis develops over the years. Because the wear and tear of a poorly tracking kneecap leads to progressive joint damage, the orthopedic screening approaches described by the COAST framework emphasize identifying and staging joint disease early (COAST Development Group, 2023).
Treatment and Long-Term Management
Treatment depends on the grade and how much the dog is bothered. Mild, occasional luxation (grade one and some grade two) is often managed without surgery through weight control, joint supplements, controlled exercise, physical therapy, and anti-inflammatory medication during flare-ups. More severe luxation, persistent lameness, or significant pain usually warrants surgery, which may deepen the groove, realign the attachment of the kneecap tendon, and tighten the surrounding tissues. Most dogs do very well after surgery with a structured recovery. Across all grades, keeping the dog at a lean body weight is one of the single most protective steps an owner can take, and ongoing wellness care helps track joint health over time (AAHA Canine Life Stage Guidelines, 2019).
When to See a Vet
Call your vet today if:
- Your dog intermittently skips, hops, or holds up a back leg then walks normally
- You notice a bow-legged stance or reluctance to jump and climb
- Your dog seems stiff or sore in the hind legs, especially after rest
- A small or toy breed puppy has an abnormal hopping gait
- Lameness is becoming more frequent or lasting longer
Go to the ER immediately if:
- Your dog suddenly cannot bear any weight on a back leg and is in obvious pain
- The leg looks deformed or there was a clear traumatic injury
- Your dog is crying out and refuses to move the limb
- There is significant swelling or an open wound near the knee
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Frequently Asked Questions
Why does my small dog skip or hop on a back leg?
An intermittent skip or hop that resolves into normal walking is the classic sign of a luxating patella, where the kneecap briefly slips out of its groove and then pops back in. It is very common in small and toy breeds, many of which are born with the tendency. While a single skip is not an emergency, a recurring skipping gait should be examined so the grade can be assessed.
Does a luxating patella always need surgery?
No. Many dogs with mild, low-grade luxation that only occasionally skip never need surgery and do well with weight control, joint supplements, controlled exercise, and anti-inflammatories during flare-ups. Surgery is reserved for higher grades, persistent lameness, significant pain, or progressive arthritis. Your vet grades the luxation one to four and considers how much it affects your dog before recommending surgical correction.
How much does luxating patella surgery cost for a dog?
An initial exam and orthopedic assessment run $50 to $200, with x-rays adding $150 to $400. Surgical correction of a luxating patella typically costs $1,500 to $4,000 per knee, including anesthesia, the procedure, and follow-up, with referral orthopedic surgeons at the higher end. Non-surgical management with supplements, weight control, and occasional anti-inflammatory medication is far cheaper for dogs that do not need an operation.
Can a luxating patella lead to arthritis?
Yes. A kneecap that does not track properly causes abnormal wear on the joint surfaces over time, which leads to progressive osteoarthritis, especially with higher grades. This is why even mild cases benefit from weight control and joint support, and why persistent or worsening luxation is often corrected surgically before significant arthritis develops. Catching and staging the problem early helps protect the joint for the long term.
How can I help my dog with a luxating patella at home?
The most powerful step is keeping your dog lean, since excess weight stresses the unstable knee. Provide regular, controlled low-impact exercise to maintain muscle without overdoing it, use ramps to reduce jumping onto furniture, and consider joint supplements and physical therapy as advised by your vet. During flare-ups, rest and prescribed anti-inflammatory medication help. These measures support the joint whether or not your dog ultimately needs surgery.
Still Not Sure if Your Dog Needs a Vet?
When you're not sure if this is wait-and-see or call-tonight, Voyage AI Vet triages in under 2 minutes. Describe what you're seeing in chat, share photos of your dog walking, the skipping gait, and how it holds the back leg, or hop on a live video call if you want a second pair of eyes. Every answer comes with citations to the actual veterinary literature it's pulling from — so you see exactly where the guidance comes from, not just a chatbot's word.