Chocolate, Onion and
Other Food Dangers For Dogs

There are some foods that we commonly eat and love which can cause illness and death if eaten by pets. 

Chocolate, macadamia nuts and onions are all good examples. Each of these foods contains chemicals which rarely cause problems for us, but for dogs and other pets, these same chemicals can be deadly. 

Should your pet eat any of these human foods no matter how little or big please contact your vet to ensure they have not eaten toxic amounts so they can stay happy and healthy. 


Chocolate toxicity

Chocolate contains theobromine and caffeine, which are both classified as methylxanthines.  Unfortunately dogs are sensitive to the effects of methylxanthines, making chocolate toxic for our pests.

After consuming chocolate out pets can become excited and hyperactive and also suffer from vomiting and diarrhoea. It is common for them to become unusually thirsty and pass large volumes of urine (diuretic effect). The effect of theobromine on the pet’s heart is the most dangerous effect. Theobromine will often increase the heart rate or may cause the heart to beat irregularly. Therefore death is quite possible, especially with exercise.

Sometimes after chocolate has been ingested, there are no obvious outwards signs that you as a pet owner may notice, and therefore you may assume that your pet is unaffected. However the signs of sickness may not be seen for several hours, with death following within twenty-four hours. Therefore, even if your dog has only eaten a small amount of chocolate, it is best to seek veterinary attention immediately. 

Usually the more bitter the chocolate the more toxic it might be. Cocoa powder and un-sweetened cooking chocolate are the most toxic forms, followed by dark chocolate, milk chocolate and then white chocolate being the least toxic. A chocolate mud cake could be a real health risk for a small dog. Even licking a substantial part of the chocolate icing from a cake can make a dog unwell. So even if you think they really want it – do not feed it or even offer a lick!

With Easter just around the corner, please take caution with chocolate in and around the house. If your pet consumes even a small volume of chocolate please contact your vet for advice on what to do. 


Onion poisoning

Onions belong to the genus Allium, along with garlic, chives, leeks and shallots. All these foods can be toxic to our pets causing sickness (and therefore should be avoided); however onions are the most toxic. The toxic component is n-propyl disulphide; this compound causes damage to red blood cells, resulting in a haemolytic anaemia, a very serious disease. 

Onion poisoning can occur with a single ingestion of a large quantity or with repeated meals containing small amounts of onion. 

All forms of onion can be a problem including dehydrated onions, raw onions, onion powder and cooked onions. Any left-over dishes/table scraps should not be fed to pets if they contain onion, no matter how small the amount of onion is.

Symptoms of onion poisoning may take time to develop. Initially you may see vomiting and diarrhoea, and may then become quiet and not interested in eating. With time, the colour of the urine may change and become dark and red. You may also see panting as the bloods ability to carry oxygen around the body can be markedly affected. 


The danger of macadamia nuts

While the toxic compound in macadamia nuts is unknown, they can be a real concern when eaten by our pets. Both raw and roasted macadamia nuts can pose a health risks for our pets. 

Symptoms of macadamia nut toxicity include depression, vomiting, weakness, muscle tremors and even paralysis.  Affected pets are often unable to get up, becoming quite stressed and will usually pant as they become quite hot. Pets can become affected by eating as few as six macadamia nuts, but the effect is variable. 

Luckily, the muscle weakness, while painful, seems to be of short duration and all pets normally recover from the toxicity. We suggest you seek veterinary attention if there is any cause for concern or suspicion that you’re pet has ingested macadamia nuts. 

It is important not to assume that human foods are always safe for pets. It is extremely important to never feed foods with chocolate, onions, garlic and macadamia nuts in them. Be sure that your pets can’t get into your stash of chocolates, that food scraps are disposed of carefully to prevent onion and garlic toxicity and that your dog is prevented from eating macadamia nuts if you have a tree in your garden. 


Other potential human food dangers


  • Pear pips, the kernels of plums, peaches and apricots, apple core pips (contain cyanogenic glycosides resulting in cyanide poisoning) 
  • Potato peelings and green looking potatoes 
  • Rhubarb leaves 
  • Mouldy/spoiled foods (keep garbage lid firmly on) 
  • Alcohol 
  • Yeast dough 
  • Coffee grounds, beans & tea (caffeine) 
  • Tomato leaves & stems (green parts) 
  • Broccoli (in large amounts) 
  • Raisins and grapes 
  • Cigarettes, tobacco, cigars 
  • Xylitol (sweetener often found in sugar-free gum) 
  • Cooked bones – they can splinter and cause gut perforation, as well as blockages in the intestine, tooth fractures, and cooked bones can get stuck across the roof of the mouth 
  • Corn cobs – a common cause of intestinal blockage requiring surgical removal 


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