Can Horses eat ...?
Food safety index

Macadamia nuts are considered toxic to horses, though the precise mechanism remains poorly characterized in equines compared to dogs. Even small quantities can trigger neurological and musculoskeletal signs in horses, making them an inappropriate feed item under any circumstances. Owners should treat any macadamia nut ingestion by a horse as a veterinary emergency.

Plain, cooked potatoes are not acutely lethal to horses, but they carry real risks that make routine feeding unwise. Raw potatoes, green-tinged skin, and sprouted tubers all contain solanine and other glycoalkaloids that can cause serious digestive and neurological problems. The starch load alone can disrupt hindgut fermentation even in toxin-free portions, so caution is firmly warranted.

Ice cream is not acutely toxic to horses, but it poses meaningful digestive and metabolic risks that make it a poor dietary choice. Most horses are functionally lactose intolerant as adults, and the high sugar content can trigger laminitis in susceptible individuals. Occasional tiny tastes are unlikely to cause serious harm, but regular feeding should be firmly discouraged.

Spinach is not acutely toxic to horses, but it contains notably high levels of oxalic acid and calcium oxalate, which can interfere with calcium absorption and contribute to urinary and gastrointestinal problems when fed regularly or in large quantities. Occasional, small amounts are unlikely to cause serious harm in a healthy adult horse, but spinach offers no nutritional advantage over species-appropriate forage and carries meaningful risks if fed habitually. Horses with kidney disease, calcium deficiencies, or metabolic conditions should avoid spinach entirely.

Apples are a classic, safe treat for horses when fed in moderation. Cut them into pieces to prevent choke, and limit the amount because they are high in sugar.