A number of foods that we eat including chocolate and salt are well-known to dog owners as harmful - but some others fly well under the radar. 

While we are sometimes inclined to treat our four-legged friends with table scraps, there are a number of foods that can pose a serious risk to dogs if eaten. 

Here is a list of some little-known ingredients found in your home that you should be aware of before feeding to your pets. 

1. Onions

Eastern Daily Press: Onions are a common household ingredient that many dog owners are unaware can be dangerousOnions are a common household ingredient that many dog owners are unaware can be dangerous (Image: Newsquest)

Onions are one of the most common cooking ingredients and are used in a wide range of dishes.

It may come as a surprise to dog owners that they are potentially very harmful to pooches.

If eaten, the root vegetable can kill canine blood cells and result in Heinz Body Anaemia which can be life-threatening. 

Look out for signs such as weakness, vomiting and breathing problems if you suspect your dog has ingested onions or even onion powder. 

2. Macadamia nuts

While macadamia nuts are edible for humans and often used in cakes and cookies, a small amount can lead to poisoning in dogs.

Macadamia nuts are high in fat and can cause pancreatitis or inflammation of the pancreas.

READ MORE: Harmful plant species in Norfolk that could poison your pet

The toxic component within the nut is unknown but poisoning begins within three to six hours of consumption with vomiting, fever and lethargy.

The next stage, six to 12 hours after eating, includes a stumbling gait, reluctance to use the rear limbs, inability to stand, joint stiffness and muscle tremors.

3. Articifical sweetener (xylitol)

Eastern Daily Press: The RSPCA recently issued a warning over xylitol which can seriously harm dogsThe RSPCA recently issued a warning over xylitol which can seriously harm dogs (Image: Newsquest)

Sugar-free gum, toothpaste and some diet foods are sweetened with xylitol which is poisonous to dogs.

It can cause a severe blood sugar drop and lead to liver failure, beginning with symptoms of vomiting, lethargy and coordination problems.

Other symptoms may include seizures caused by hypoglycaemia.

Dog owners are warned to carefully check any food that may contain sugar alternatives or low-sugar ingredients.

4. Avocado

 According to information provided by ASPCA, the leaves, fruit, seeds and bark of avocados contain persin, which can cause vomiting and diarrhoea in dogs. 

Persin is not harmful to humans but the large seed can cause a choking hazard for dogs and humans alike. 

READ MORE: Where lungworm parasite has been reported in Norfolk

Like macadamia nuts, the high-fat content in avocados poses a high risk of pancreas inflammation and pancreatitis.

5. Grapes and Raisins

Eastern Daily Press: Grapes, raisins, and other currents pose a serious risk to our four-legged friends says the RSPCAGrapes, raisins, and other currents pose a serious risk to our four-legged friends says the RSPCA (Image: Newsquest)

Grapes, raisins, sultanas and currants are all potentially poisonous to dogs and if eaten they can cause gut problems and in serious cases - kidney failure.

The RSPCA say any quantity of these can be toxic and cooking or baking doesn't reduce the risk of poisoning.

Poisoning may initially result in vomiting and diarrhoea and subsequently in acute renal failure.