It is not recommended for cats to eat banana bread due to potentially harmful ingredients found in them.
Banana bread is a tasty treat typically consisting of overripe bananas, flour, butter, eggs, sugar, salt, baking powder/soda, and ground cinnamon. Other recipes include nuts (typically walnuts), milk, and chocolate chips.
ASPCA lists bananas as non-toxic to cats and dogs. Plain bread is similarly safe for cats to eat in small amounts. But because of all the other raw ingredients needed to make banana bread, it is not advisable to feed it to your cat. This is especially the case when the banana bread is store-bought, and you are unsure of all the ingredients and preservatives used.
Cats are obligate carnivores that need animal-derived protein. Banana bread is packed with sugar and carbohydrates, which are not needed by your cat. When fed too much of these, your cat may experience vomiting, diarrhea, and discomfort. Feeding her banana bread regularly can also lead to weight gain, diabetes, tooth problems, and other health conditions.
What to do if your cat accidentally eats banana bread: Take note of all the ingredients in the banana bread. If there are high amounts of lethal ingredients (particularly chocolate, walnuts, and cinnamon), contact your veterinarian immediately.
Common symptoms of cat poisoning include the following: salivation, vomiting, diarrhea, twitching and fitting, breathing difficulties, shock or collapse, inflammation or swelling of the skin, depression or coma, and changes in drinking, urinating, and appetite.
In summary: Banana bread may seem like a healthy snack for cats, but feeding her this treat will do more harm than good in the long run. Instead of serving her banana bread packed with unnecessary nutrients, give her fresh fruits and vegetables. Limit these to 10% of her daily diet since her total calorie intake must consist mainly of animal-based protein.