Limping Dog

Limping is mainly caused by pain or weakness, with pain being more common. If a dog is limping, I generally assume they are in pain, even if they aren't showing other obvious signs. It's very common for dogs to "push through" pain when they're doing something fun or rewarding, so I'm not surprised she's still running around.

Talk to your vet about getting a referral to a specialist. Depending on what's available in your area, this could be a rehab vet, a sports medicine vet, a rehabilitation therapist (essentially an animal physiotherapist, but I think "physiotherapist" is a protected term in the US so you can't use it if you work on animals), or a veterinary chiropractor. These are people with more specific training in assessing and addressing structural pain and weakness. General vets are wonderful, but they have to have a lot of broad knowledge, which sometimes means they need to rely on specialists for subtle or complex problems outside their expertise.

If a specialist isn't an option for whatever reason and your vet still can't find any cause for the limping, ask them about whether trying a trial of pain medication is possible. If the limping stops on painkillers, that's a pretty good indication that there's something causing pain, but at least you have a way to keep them more comfortable.