There is a whole list of food toxic to German Shepherds or dogs in general. Most people have heard about chocolate and alcohol, but here are some others and their possible effects:

• Grapes and raisins – renal failure
• Macadamia nuts – muscle tremors, weakness or paralysis
• Tomato leaves and stems – heart arrhythmias
• Pear pits, the kernels of plums, peaches and apricots, apple core pits – cyanide poisoning
• Milk and dairy products – diarrhoea (in some dogs)
• Avocados – oedema in chest and heart, leading to difficulty breathing
• Onions – gastroenteritis, haemolytic anaemia, hepatic impairment
• Garlic is less toxic so would need to be ingested in larger quantities compared to onions. Garlic in small quantities can be used in certain dietary supplements