Which famous artist painted this Mastiff?

Here are three clues:

1. The artist was a Spanish Baroque painter from Spain.

2. This image s a detail from his most famous painting.

3. The painting hangs in the Prado Museum in Madrid..

Answer: Diego Velasquez, Las Meninas, 1656, oil on canvas

Source:

https://www.museodelprado.es/en/the-collection/art-work/las-meninas/9fdc7800-9ade-48b0-ab8b-edee94ea877f