Gave my dog a double dose of prednisone tonight . He seems a bit loopy- does he need to go to the emergency room

I accidentally gave my dog a double dose of prednisone tonight so instead of 10mg he got 20mg. He weighs 50 lbs. He seems a bit lethargic and off balance. Am I best to take him to an emergency vet tonight ?

• Species: dog
• Age: 15
• Sex/Neuter status: M fixed
• Breed: golden retriever
• Body weight: 50 lbs
• History: mast cell cancer
• Clinical signs: lethargic, wobbly
• Duration: had double dose 2 hours ago
• Your general location: denver, Colorado
• Links to test results, vet reports, X-rays etc.