How much onion is toxic to dogs if swallowed? It is well-documented on the internet and elsewhere that onions and for that matter, other members of the onion family such as garlic and chives can be poisonous to dogs if swallowed. This often causes owners to panic when their dogs eat foodstuffs such as pizza which have some degree of onion content. But what are the facts?
How much onion is toxic to dogs if swallowed?
Thankfully it actually takes quite a lot of onions to be toxic to dogs in terms of serious side effects. The rule of thumb which I personally apply is that a single meal of one pound of onions taken at one sitting can be dangerous to a 15 pound dog. { Which is quite a small dog } However be aware that smaller amounts of onion fed on a regular day in day out basis can still eventually cause serious side effects such as anaemia. Actually, in my experience problems related to onion toxicity in the dog are quite a rare event because the average dog is unlikely to eat whole raw onions and normally the amount ingested in pizza and other human foods are fairly minimal.
What is it in onions which make them toxic to dogs?
The culprit is compounds called disulfides and thiosulphates, unlike humans, dogs lack the enzymes to metabolise these. If consumed in quantity these cause conditions such as haemolytic anaemia, Heinz body anaemia, and methemoglobinaemia, the effects of these is to cause damage to red blood cells. Basically, these compounds cause the dog’s red blood cells to become fragile and degrade.
What are the symptoms of onion toxicity in the dog?
Where a dog has eaten a significant quantity of onions which is below a seriously toxic dose then you would see symptoms such as drooling, vomiting, diarrhoea and lethargy. But the dog will be likely to recover from this over three of four days. These symptoms will occur in the first few hours after onion ingestion.
Where a large toxic dose has been ingested at first you will see the above symptoms. But then some days later the symptoms will start to appear which are related to the damaged red cells. These will include such things as pale gums and mucous membranes, blood in the urine, an elevated heart and respiratory rate and extreme exercise intolerance leading to collapse.
What treatment is available where a dog has eaten large amounts of onions?
How much onion is toxic to dogs? What do you do when you suspect a toxic amount has been swallowed? As with a great many toxins if you can induce vomiting to recover the onions within the first hour after ingestion { Two hours at the very outside } then things should be OK. Please follow this link for precise instructions on how this can be best done: LINK
At this time activated charcoal given orally as soon as possible after ingestion can often mop up some of the onion toxins, doses of around 2 gram per pound of the dog’s body weight given three times a day for a few days have been used.
After that where a small amount of onion have been swallowed and you are seeing some degree of gastroenteritis then normal common-sense measures may be enough to settle things down.
However, if you are suspicious that anywhere near a toxic dose of onion has been consumed by your dog then you have no course other than getting your dog to a vet as soon as you possibly can.
Of course, your vet may induce vomiting and give activated charcoal if you can get there quickly enough. But once clinical signs develop then a high level of supportive care is required, but in addition, supportive care such as oxygen therapy, and some dogs may require a blood transfusion.
Onion toxicity and cats.
In theory cats would be just as open to onion toxicity as dogs, however, the nature of the cat is to be very fastidious in what they eat, so much so that onion toxicity is very rare in the species. I for one have never seen a case.