Joel just weighed his dog and found out that it weighs 117 kilograms. The last time he weighed the dog he weighed 90 kilograms. What percent heavier is the dog now?
The increase in weight is 117 kg - 90 kg = <<117-90=27>>27 kg.
To find what percent heavier the dog is now, we divide the increase in weight by the previous weight and multiply by 100%: (27 kg / 90 kg) * 100% = 30%.
Therefore, the dog is now 30% heavier. Answer: \boxed{30}.