Friend, as you may already know the limping is secondary to the swelling of the toe. The big question is then: Why is the toe swollen? This can be caused by many different medical conditions. It will not be possible for me to determine the exact underlying cause without a hands-on examination and some testing, I am sorry. But, common causes are a soft tissue injury, a fracture, an insect sting, tumor, an infection, etc. to name a few causes. This is what you can do:
1- Do not let her lick the toe or she will make it worse. If she does lick pick an e-collar (cone) in your local pet store to stop her from licking.
2- Soak the affected paw in warm water with epsom salt for 5 minutes 3-4 times a day.
3- Rest her; no running or jumping. Activity should be limited to urinate and defecate on a leash.
4- If no significant improvement within 1-2 days after doing the above I would have her checked by your family veterinarian for a hands-on examination.
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