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The Guardian - UK
The Guardian - UK
Phil Samba

From grapes to avocados: 10 human foods that dogs can’t eat

From above dog watching cookies with chocolate. Harmful food for dogs.
Sharing food with your dog can lead to a host of health problems. Photograph: Israel Sebastian/Getty Images

A human’s digestive system is vastly different from a dog’s – they have much shorter intestines, and many of the foods we eat can be too fatty, rich or toxic for dogs. The wrong foods can lead to diarrhoea, vomiting, dehydration and, in some severe cases, organ failure, pancreatitis and even death.

It is always kinder and safer to feed dogs food that is designed for them. Pet food manufacturer Royal Canin, for example, tailors recipes, kibble shape and serving size to specific breeds, sizes and ages of dogs, all of which are devised by qualified and board-certified pet nutritionists.

Here are 10 seemingly innocuous foods that can cause a whole host of problems for your pooch.

Corn on the cob
“Dogs don’t have digestive enzymes in their mouth like we do, so they don’t need to chew in order to start the chemical digestion process – this means they can swallow something whole or barely chewed, which can be dangerous,” says Clare Hemmings, scientific communications manager at Royal Canin. “It’s not corn itself that is hazardous to dogs, but ingesting a cob can cause an obstruction, which can lead to devastating effects on the digestive system, such as intestinal ruptures. I’ve encountered a dog who came in repeatedly for surgeries to remove a cob from its intestinal tract, which caused scar tissue to the intestines.”

The symptoms of intestinal blockage can include vomiting, lack of appetite, and collapsing.

Chocolate
“The thing with chocolate is that your dog is unable to metabolise the stimulants caffeine and theobromine that are naturally found in cocoa, and it’s often at festive periods like Christmas and Easter when the risk of dogs eating chocolate increases,” says Hemmings. “If your dog consumes chocolate, it could lead to dehydration, diarrhoea and vomiting. Dark chocolate has the highest content of theobromine, and can cause organ failure.” Hemmings is also wary of “doggy chocolate” made from carob – a powder extracted from the pods of a carob tree, native to the Mediterranean. Although it doesn’t contain caffeine or theobromine, and therefore isn’t toxic to dogs, “it can give dogs a taste for chocolate and also confuse dog owners into thinking that regular chocolate isn’t harmful”.

Xylitol
“Diet and sugar-free products often contain xylitol, an artificial sweetener that is almost as sweet as sugar but much lower in calories. Eating it is dangerous for dogs as it can lead to them having a sudden drop in blood sugar levels (called hypoglycaemia) due to the release of insulin. The symptoms are severe and include weakness, seizures, convulsions, and even death,” says Hemmings.

Grapes and raisins
Grapes and raisins are highly toxic to dogs, with even trace amounts causing serious problems. “No one knows the precise reason they are so dangerous to dogs, and some dogs are more sensitive than others, meaning a very small amount can lead to rapid kidney failure and death in a matter of days. It is as dangerous for dogs to eat cooked raisins, in foods such as fruit cakes or mince pies, as it is if they’re raw,” says Hemmings. “Mycotoxins are the suspected cause, but this hasn’t been confirmed. The signs your dog has eaten grapes or raisins are vomiting, tremors, lethargy, dehydration and even collapse.”

Sliced avocado on a chopping board.
Avocados should be avoided as they contain the toxin persin. Photograph: Shikhar Bhattarai/Stocksy United

Alliums (onions)
Perhaps the strongest argument for not giving dogs human foods is the ubiquity of alliums. All types of onions – including spring onions as well as chives, garlic, leeks, and shallots – are dangerous to dogs. “Alliums contain a toxic sulphur compound called n-propyl disulphide, which can harm your dog’s red blood cells,” says Hemmings. “This makes them less effective at moving oxygen through the body, which can cause anaemia and weakness. Signs of illness are not always apparent immediately and can occur up to a few days or even a week later. It’s cumulative, so one piece is unlikely to do harm but, over time, many small pieces, fed regularly, could affect the dog’s heart rhythm, which is potentially serious.”

Avocado
“Avocados contain the toxin persin, which can cause fluid to accumulate in your dog’s lungs, leading to difficulty breathing, oxygen deprivation and even death,” says Hemmings. “If you’re preparing avocado, and a bit falls on the floor your dog would be fine if they ate it – they’d have to be consuming a lot over a period of time for it to be a problem since the flesh of the avocado contains very low levels of persin. However, there’s no benefit and a potential for harm, plus avocados are high in calories, so it’s best avoided.”

Yeast dough
“Yeast dough eaten raw can rise and ferment in your dog’s stomach. The fermentation can cause your dog’s stomach to stretch to the point of pain and bloating – it could cause a blockage in their guts and release toxic levels of ethanol into the bloodstream, causing alcohol poisoning,” says Hemmings.

Alcohol
Similar to the caffeine in chocolate, dogs are unable to metabolise alcohol, so any beverages, foods or even household products with different forms of alcohol are not only extremely unhealthy but can also be toxic. “Alcohol can cause dangerously low body temperature, hyperventilation, and disorientation in dogs, and in extreme cases, can lead to organ failure. It’s never OK to feed alcohol to dogs,” says Hemmings.

Nuts
“Dogs can’t have macadamia nuts as they contain a toxin that can lead to fever, muscle weakness, vomiting and tremors. Almonds are not toxic, but they can block the oesophagus,” says Hemmings. Salted almonds or peanuts could increase water retention, which can be serious for dogs prone to heart disease. All nuts are best avoided since some contain natural toxins called juglones, and all are high in calories and too fatty for dogs, particularly small breeds.

Mouldy food
This is arguably one that a lot of dog owners don’t know about. “Mouldy food can contain mycotoxins that could make your dog very ill. There once was a child who left a sandwich in his lunchbox and forgot about it – the dog got into his bag and ate it, and sadly passed away a few days later,” Hemmings says.

The symptoms of mycotoxin poisoning are agitation, fever, vomiting, tremors, seizures and even death.

Shop the Royal Canin range and find the perfect food for your dog at royalcanin.com

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