Final answer:
The adjectives 'miniature' and 'appropriate' describe ponies in the context of acting as guides. The breeding of smaller pets like 'teacup' breeds, despite their associated health risks, is also mentioned.
Step-by-step explanation:
The question involves identifying adjectives in the sentence: "Miniature ponies show promise as guides for the blind. They perform well and are appropriate for those." The adjectives in this sentence are miniature, which describes the size of the ponies, and appropriate, which describes the suitability of the ponies for potential users.
Further discussing the role of animal size in domestication and their use as service animals, we can refer to the information given that describes the trend of breeding smaller animals. It highlights the popularity of teacup breeds in urban living environments, despite the health risks associated with extreme miniaturization like collapsing tracheas and heart defects.