Here's what we know:
* Brain weight: A Chihuahua's brain weighs around 0.5-1.0% of its body weight. This is significantly less than larger breeds, which have brain weights closer to 2% of their body weight.
* Relative size: While the Chihuahua's brain is small, it's not necessarily a sign of lower intelligence. Their brains are highly efficient and have a high density of neurons. This means they have a large number of brain cells packed into a small space.
Important Note: It's crucial to remember that brain size doesn't directly correlate with intelligence. Many factors, including genetic predisposition and environmental influences, contribute to a dog's cognitive abilities.