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Common foods toxic to dogs

Many common foods can make your pet ill. Some, ingested in sufficient quantity, can kill. If your pet eats large quantities of any of the foods listed here it’s critical that you call us and get your pet to the hospital quickly.

The ‘treat’ that’s toxic to dogs

At Alpine Animal Doctors we put chocolate at the top of the toxic foods list because it’s one food that dogs particularly crave, and will eat as much as they can get their greedy teeth into. You should never feed your dog chocolate. While a tiny piece is not likely to trigger toxicity it’s better for your pet if they never experience the taste at all.

Chocolate contains both theobromine and caffeine. These are methylxanthines and dogs are very sensitive to them. Depending on the amount ingested the effects of methylxanthines can include vomiting, diarrhoea, hyperactivity, increased heart rate, low blood pressure, seizure and tremors. We may also see increased thirst, more frequent urination, and lethargy.

These symptoms can lead to heart failure, coma and death within 12 to 36 hours of a dog overdosing on chocolate.

The amount of methylxanthines in chocolate varies. White chocolate has the lowest levels, followed by milk chocolate. Dark chocolate is the most dangerous. Gram for gram, unsweetened baking chocolate contains almost seven times the amount of theobromine as milk chocolate. The general rule is the more bitter the chocolate, the more toxic it will be.

Early treatment is vital. Once your pet reaches the hospital we will initiate decontamination procedures by making your dog vomit and tubing activated charcoal into the stomach. We may also use IV fluids to aid in eliminating toxins from the animal’s system. We will also use heart monitoring and supportive care. Treated early enough, most pets will recover from chocolate toxicity with no lasting damage.

Fried or sliced, onions are bad for pets

Onions come a close second to chocolate. All members of the onion family — garlic, leeks, chives, shallots et al — are toxic to pets, including onion powders and cooked onion.

Onions and garlic contain the toxin thiosulphate, which dogs and cats cannot break down. Thiosulphate can burst the red blood cells of dogs, causing haemolytic anaemia. Poisoning is usually seen a few days after the animal has eaten onions. Symptoms include vomiting and diarrhoea, very pale gums, blood in the urine, lethargy and anorexia. Their urine turns red and they become breathless due to the lack of red blood cells available to carry oxygen.

Effective treatment relies on early diagnosis and palliative care — treating symptoms as they arise. We will induce vomiting if the onion has been eaten in the previous two hours, we will administer activated charcoal to bind the offending material in the gut. If they are suffering from severe anaemia, a whole-blood transfusion will be necessary.

Not a health food for dogs 

Macadamia nut poisoning is often not as drastic as other food toxicities but swift treatment is just as important. Dogs can develop symptoms from eating as few as six to eight kernels, raw or roasted, or even macadamia butter.

Affected dogs will usually develop clinical signs within 12 hours and present with muscle tremors with weakness or paralysis of the hindquarters. Other symptoms can include vomiting, inability to walk straight, and a high temperature.Their limbs can become swollen and some owners report pain on movement of the legs.

Treatment involves administering activated charcoal, enemas and fluid therapy. With prompt treatment most dogs survive macadamia poisoning with no permanent damage. Macadamia poisoning has not been seen in cats.

Don’t peel them a grape!

Grapes and raisins are a recent addition to the list of toxicities seen in pets. The toxin involved has yet to be isolated but is suspected to be a mycotoxin that causes acute kidney failure. Initial symptoms are vomiting and diarrhoea within a few hours of ingestion, followed by weakness, anorexia, increased thirst and stomach pain, then acute renal failure within 48 hours of eating the offending material.

Treatment is by control of absorption if possible — inducing vomiting if eaten within two hours — or via activated charcoal to bind toxins within the gut. Intravenous fluid therapy is also used to manage renal failure.

Unfortunately, the damage that can be done in a short period means recovery is always uncertain, and if there is weakness, no urinating or high calcium levels in the blood the prognosis is invariably negative.

Sugar substitutes are dangerous to dogs

Xylitol toxicity is another relatively recently identified toxin. A naturally occurring sugar substitute it is used extensively in sugar-free lollies and chewing gum. It takes only small amounts of xylitol — as little as half a gram per kilo — to cause toxicity. Unlike in humans, in dogs xylitol is absorbed very quickly into the blood where it stimulates insulin release, causing profound low blood sugar leading to liver failure, bleeding, and death.

Vomiting is the first sign, with symptoms of hypoglycaemia occurring rapidly, followed by diarrhoea, collapse and seizures. In some cases dogs have developed acute liver failure with no signs of hypoglycaemia.

There is no antidote and treatment can only be palliative. The prognosis for uncomplicated low blood glucose is good, however, those animals that develop liver failure or fall into a coma have a very poor prognosis.


No dough for dogs

Ingestion of yeast/bread dough can be fatal to dogs because the dog’s body heat will cause the dough to rise in the stomach, often to several times its original size.

Symptoms seen with bread dough ingestion are caused by the ethanol produced during the rising process, and by foreign body obstruction. Symptoms may include severe abdominal pain, bloating, vomiting, lack of coordination, and depression.

Treatment, in cases of recent ingestion, involves inducing the animal to vomit. We may also administer cool water via a stomach tube to try to halt the rising process. Pain relief is also usually needed. In severe cases we may need to remove the dough surgically. Ethanol can cause an acidosis so we will also monitor blood parameters through ongoing blood tests.


If it’s off, keep it away from pets

Spoiled foods that are growing mould, whether in the bin or outdoors, can also be poisonous. All moulds contain mycotoxins. Some can contain tremorgenic mycotoxins, which can induce muscle tremors, ataxia, and convulsions that can last for several days. Effects have been reported in many species although dogs that roam are more at risk. The degree of severity of symptoms can vary from mild to severe, depending on the particular mycotoxin ingested.

Treatment for tremorgenic mycotoxin poisoning includes halting or minimising absorption by making your dog vomit, lavaging the stomach, and tubing with activated charcoal. The hospital will also attempt to control tremors and seizures using drugs delivered intravenously, and providing supportive care with IV fluid therapy. With early, appropriate treatment, prognosis is good for most pets.

But wait, there’s more…

Although the foods listed above are the most dangerous of foods toxic to your furry friends there are others, including potato peelings, the pips from pears and the kernels from stone fruit such as peaches, which can cause cyanide poisoning. All parts of the avocado are toxic to dogs, as are the leaves and stems of the tomato plant. Broccoli, eaten in large quantities, can be poisonous too.

While these may not be as life threatening as the major toxic foods, they can definitely make your cat or dog very ill. Animals are going to continue to poison themselves because they have no idea what’s good for them, or what’s bad for them. We can never hope to eliminate those bad habits but pet parents do need to be vigilant — especially about that enticing chocolate cake left out on the kitchen bench.


E&OE. The information provided in the articles on this site is intended as a guide to assist readers to become better informed about health issues that may affect their pets and livestock. They are not a substitute for appropriate veterinary advice and treatment. They should not be used for diagnosis or treatment of any individual animal and no person should place reliance on information derived from them, where such reliance may result in loss, damage or injury. Always consult a qualified veterinarian to obtain advice.

Although Alpine Animal Doctors make every effort to ensure that the information contained in our articles is accurate and up-to-date we can accept no responsibility for errors or omissions that may occur.