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Why Do Dogs Eat Grass?

A problem mystifying veterinarians and dog owners, the answers aren’t black and white. But, since grass ingestion rarely causes a linear foreign body in the gut (think hoddie string with a buried end creating an accordion effect on the hood), a complete gastrointestinal obstruction or toxicity if chemicals are present, there’s been little research on this. Some research has been published by Dr. Karen Sueda, et al in the journal Applied Animal Behavior.

Surveys online & patients at UC Davis provided insight with owners reporting 79% of dogs exposed to plants daily had ingested some greenery.  Of those 68% did so daily or weekly but the remainder did so monthly or less. 79% of ingesters frequently chose grass but only 9% of those appeared ill before ingestion. 22% vomited afterwards. That confirms what dog owners already know: grass eating is pretty popular among many dogs while others don’t indulge and certain dogs seem to really have a taste for it and occasionally it causes vomiting.

Neither gender, neuter status, breed group or diet type predicted which dogs ate plants. The thing plant-eating dogs had in common was a young age. Young dogs less frequently showed signs of illness prior to ingestion but did show less vomiting afterwards. I believe the parasite theory as the cause for grass eating because younger dogs have more parasites. Whether your younger dog actually does depends on lifestyle and veterinary care but an instinct for young dogs to eat grass is proposed. Parasites may be dislodged when roughage passes through the digestive tract and migrating hookworms especially cause an “itchy esophagus.” Some unlucky owners have seen their puppies vomit worms so stimulating vomiting does clear some parasites.

Realistically, dogs likely eat grass for many reasons. Though grass has fiber and vitamins, canine stomachs like ours, are not capable of utilizing it. Some grass eaters are diagnosed with stomach ulcers and did stop when treated. Some veterinarians believe vomiting is the goal so fur and bones of prey that would not pass in wild ancestors of our dogs passed down the doggy instinct to eat grass if your stomach is upset. The last and most difficult to determine cause is behavioral. Disnterest in current activities, boredom or compulsion could make grass eating an entirely different animal.

So, what to do about grass eating? We recommend the following: don’t allow overindulgence, be sure the grass hasn’t been treated, de-worm your dog annually, keep an eye out for unhealthy stools and if you’re battling a real obsession try a putting half a meal in a treat ball if boredom is suspected. Of course, see your vet if you become concerned about any feeding behavior in your dog. The last thought which is a good idea is try a bedtime snack for grass hounds since a sour empty stomach in the morning may induce grass eating. Happy Spring from all of us here at Woof and Purr Vet!

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