My 10-year-old small dog is limping and won't walk. What's wrong?

Thank you for submitting your question regarding Osito. There are many causes of lameness in a dog. Start by checking his paw to ensure there is not something stuck in his fur or a broken toe nail. He would likely be licking the paw in this case. If not, then he could be experiencing arthritis. This is common in the hip and knee joints. Other possibilities are a displaced kneecap, a torn ligament in the knee, a fractured leg, a bone tumor or an autoimmune disease attacking the joints. He will need to see his veterinarian to determine where he is painful. X-rays will likely be recommended. In the meantime, keep him quiet to allow his body to rest. Do not give any over-the-counter pain medications as these can be toxic to dogs. I hope this information helps!