Why can’t dogs eat onions?

Dogs love table scraps and loving owners would gladly share whatever food they are eating with the pet. Some human-safe foods though have harmful effects on our four legged friends. Some people foods can make the dog seriously ill. It would be a dog owner’s responsibility to know what these foods are and to ensure that the pet is kept away from these harmful foods.

Onion is a cooking ingredient that causes sickness in dogs. Dogs must be prevented for ingesting onions as canine stomachs don’t have the enzyme necessary to metabolize the theosulphate substance contained in these pungent bulbs. What is more alarming with onion toxicity is the fact that it is dose dependent. Small amounts of onion consumed may not have visible harmful effects on the dog. As such the dog will be fed salsa, pieces of pizza, hamburgers and any many other people safe food. Table scraps will go directly to the food bowl of the dog. However, extended period of consuming small amounts of onions will result to accumulated toxicity. Serious medical concerns can result to the death of the dog.


How does onion toxicity affect the dog? Hemoglobin in the red blood cells transports the oxygen from the lungs to the rest of the body to be used by the cells. When dogs ingest onions, the thiosulphate that is not digested by the dog’s stomach will oxidize the hemoglobin causing the formation of bubble-like clumps in the red blood cells. These clumps that stick out from the cells are called Heinz bodies. Continued ingestion of onions will result to the formation of more Heinz bodies. These bubble-like clumps will eventually rupture causing the red blood cells to be prematurely destroyed. Bone marrows repair damaged blood cells but significant formation of Heinz bodies renders the work of the bone marrow ineffective. This is when the dog would manifest onion toxicity symptoms. Because less oxygen are delivered to the body of the dog, the functions of the vital organs will be hampered. The affected dog will weaken and be lethargic. Other symptoms would be vomiting and diarrhea, increased heart rate, bloody urine, jaundice and decreased appetite. The poisoned dog will have breathing difficulties. Continued onion consumption and non-treatment will eventually result to the death of the dog.

This concern was aggravated by the fad of feeding dogs with homemade foods. Dog owners are aware of the hidden dangers of feeding the pet commercial dog foods so that what is eaten by the family will also be given to the pet. Home cooking will in fact be healthier for the dog but be very sure not to use onion as an ingredient.

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