The Toxic 10 – foods that pets should never eat and how to treat

1. Chocolate

Christmas is a peak time for chocolate toxicity in dogs. According to the Veterinary Poisons Information Service, 20 percent of all cases of chocolate poisoning in dogs reported to them, occur in December. The toxic component in chocolate is theobromine, with dark chocolate containing the most and milk chocolate a little less. White chocolate, with no cocoa solids, contains no theobromine and so presents no risk of toxicity.

Grapes and their dried products have been associated with renal failure in dogs. The mechanism behind grape toxicity in dogs is unknown and not all dogs are at risk. Indeed, there is considerable variability between individuals in terms of susceptibility. In one study, some animals developed no clinical signs after eating one kilogram of raisins, while a handful of raisins proved fatal to others.¹

So that also means…

In addition to the ‘my dog ate a raisin’ out of hours call, mince pies, Christmas pudding, and Christmas cake are a canine no-go and responsible for a spike in poisonings in the festive season.

As manufacturers strive to reduce sugar to appeal to health conscious consumers, xylitol is an ever more common feature of foods and is found in everything from peanut butter to chewing gum, ice cream and candy canes. This artificial sweetener is a potent stimulator of insulin release in dogs, leading to a rapid onset of hypoglycaemia. In addition, xylitol has been associated with liver damage, although the mechanism behind this is not known. The VPIS recommend treating for any ingestion over 50mg/kg, taking baseline bloods to include glucose and liver enzymes and monitoring blood glucose every one to two hours for a minimum of 12 hours.

Onions, garlic, and other members of the Allium family are toxic to dogs. Onion toxicity in dogs can result in haemolytic anaemia with an onset as soon as 12 hours after ingestion. Anaemia is characterised by the formation of Heinz bodies in red blood cells.

Eating uncooked bread dough can cause two problems due to the fermentation of yeast. For starters, the dough expands and can cause gastric distension and GDV, and secondly the production of ethanol can cause intoxication. Treatment may require repeated gastric lavage, especially if there is non-productive vomiting.

Not just found in the kitchen, salt can also be found in salt dough modelling clay (often used to make Christmas decorations), dishwasher salt and water softeners. It increases plasma osmolality, resulting in cellular dehydration, vomiting and diarrhoea, neurological signs, and even renal failure. Treatment is supportive with cautious use of intravenous fluids.

Ingestion of mouldy food can result in a condition called tremorgenic mycotoxicosis. Clinical signs of this form of food poisoning in dogs, typically start from 30 minutes to three hours after ingestion. They include tremors which may be seizure-like, hypersalivation, panting, pyrexia and nystagmus. Treatment is supportive and lipid infusions can be effective as fungal metabolites are lipophilic.

Reports vary as to the toxicity of avocado. Persin, found in leaves, unripe fruit and the avocado seed, is potentially toxic. However in reality, vomiting and diarrhoea is the most commonly seen sign, and then only if the fruit is unripe. Supportive treatment including intravenous fluids or probiotics can be considered if required. The biggest concern comes from intestinal obstruction if the stone is eaten.

Just as in people, alcohol is a CNS depressant. Once consumed, signs generally appear within one to two hours. Cats in particular may like the taste of cream-based drinks; 1-2ml/kg can give clinical signs of poisoning and is little as 5-8ml/kg can be lethal. Supportive treatment is appropriate in most cases, but a competitive inhibitor of alcohol dehydrogenase can be used in more severe intoxications.

The mechanism behind macadamia nut toxicity is unknown but it only seems to affect dogs. Clinical signs include vomiting and abdominal pain, muscle tremors, weakness and hyperthermia. Treatment is largely supportive to include gastric decontamination, intravenous fluids and muscle relaxants if necessary. With appropriate management the prognosis is good.

So that concludes our top 10 toxic foods for dogs. By no means a comprehensive list – it would be relatively easy to come up with a collection of 20 foods harmful to dogs by the time you have added….

• Caffeine and coffee grounds
• Fatty foods including turkey skin and ham
• Apricots, cherries and peach
• Liquorice
• Protein bars (they may contain xylitol)
• Dairy products
• Liquorice
• Corn on the cob (not strictly toxic, but intestinal blockages are a risk)
• Raw potato
• Hops

So…is Christmas dinner bad for dogs?

While most pet owners want to include their four-legged friends in seasonal festivities, Christmas dinner can be bad for dogs. With onion and turkey skin, plus Christmas pudding, mince pies and chocolate to name a few, Christmas dinner is not always dog-friendly. Educating pet owners on which foods are best avoided is key to keeping pets happy and healthy, and to reducing those out-of-hours festive phone calls.

References