August is the time when many gardeners in the UK begin harvesting onions and garlic after months of growing. These popular vegetables are often ready to pull from the ground at this time of year, depending on when they were planted.
According to the Royal Horticultural Society (RHS), onions planted in spring are usually harvested in late summer or early autumn. But if they were planted in autumn, they’ll be ready earlier, typically in early to mid-summer. Garlic follows a similar pattern. Autumn-planted garlic is often harvested around June or July, while spring-planted garlic tends to be ready by the end of July or into August.
But while gardeners may be eager to enjoy the results of their hard work, experts are warning pet owners to be cautious, because both onions and garlic can be highly toxic to dogs.
The vet charity PDSA said alliums, which include onions, garlic, leeks, chives, and shallots, contain harmful compounds that can damage a dog’s red blood cells.
These toxins, disulfides and thiosulfinate, can cause vomiting, diarrhoea, and even lead to anaemia if consumed in large enough quantities.
Even small amounts of onion or garlic, whether raw, cooked, or dried, can be dangerous. The PDSA warns that symptoms may take a few days to appear, though they can sometimes begin within 24 hours.
They include a sore stomach, reduced appetite, dehydration, weakness, and in more serious cases, difficulty breathing or seizures.
If a dog has eaten any of these plants, owners are advised to contact a vet straight away. “It’s best to treat poisoning as soon as possible,” the PDSA said. “With treatment, most dogs recover well.”
Treatment could involve making the dog vomit, administering activated charcoal, or giving fluids through a drip.
Blood tests may be used to check for anaemia, and medication might be given to manage symptoms such as vomiting or seizures.
Pet health site PetMD has also issued a warning about garlic, saying it is around five times more toxic to dogs than onions or leeks due to its higher concentration of harmful compounds.
They warned that eating even 2g of garlic per pound of body weight can cause illness, and said around 10 cloves could be enough to make a 25lb dog seriously ill.
They added that there is also no evidence that garlic can be used to treat fleas, and that it should never be given to dogs, even in small amounts.
Lastly, experts are reminding gardeners to be mindful of where they leave harvested onions or garlic and to make sure pets cannot access vegetable patches where the plants are still growing.