Can a Chihuahua eat pineapple?
Fresh only, and just a little.
How much: 1 small piece, never canned in syrup.
Why
Pineapple has bromelain (a helpful enzyme) but also a lot of sugar and acidity. Start with one small piece.
Pineapple in a Chihuahua's diet
Keep in mind how tiny the portions are for this breed: an adult Chihuahua eats roughly 1 to 2.3 ounces (25-65 g) of food a day depending on his weight, and treats shouldn't go over 10% of his daily calories. That's only a small fraction of an ounce. What looks like "a little bite" to us can be half a meal for him.
This information is for general guidance and is not a substitute for advice from a licensed veterinarian. Every Chihuahua can react differently; if in doubt, always check with a professional.