Why does your dog eat grass?

There is hardly any dog who has not eaten grass in his life time. Grass eating in dogs is a general complaint by the pet parents. Some believe dogs eat grass to correct their upset stomach while others believe that they eat when they want to vomit. Here are few myths and facts surrounding dogs eating grass.

Common myths surrounding dogs eating grass
Myth 1: Dogs eat grass as a natural remedy to ease upset stomach.

Fact: Grass eating in dogs is not always associated with illness, despite the common beliefs that the dog eats grass to treat upset stomach. It has not been proved that upset stomach would induce the desire for grass eating.
Myth 2: Dogs eat grass to vomit.
Fact: Many times grass may contain faecal residue from other dogs having parasitic infestation. Ingestion of such infested grass may cause active infection and illness, or they may vomit.
Myth 3: Dogs eat grass when they are sick.
Fact: Ingestion of grass sprayed with pesticide or herbicide may cause illness.
Myth 4: Dogs eat grass to improve digestion.
Fact: Unlike cats, dogs are neither true carnivores nor garden-variety omnivores. They had been opportunistic scavenger eating anything and everything to fulfill their dietary requirements. With the passage of time owing to evolutionary process and domestication, the scenario has changed and today’s dog is different from his ancestors in eating habits. Instead, dogs today eat plants or grass as an alternative food source.
Why do dogs eat grass?
A number of theories, ranging from physical to psychological to natural instinct, have been put forward as to why dogs eat grass. Different dogs eating grass may have different reasons.
Theory of natural instinct: As a matter of fact, dogs are not natural carnivores but are omnivores of certain type. Before their domestication they thrive naturally on prey items. i.e. meat, bones, organs and stomach or intestine contents. Today the situation is different and dogs do not depend on prey for their food needs. But some dogs may still possess the natural scavenging instinct. It appears that for domestic dogs, grass eating is to satisfy their hidden natural instinct.
Theory of psychological imbalance: Another school of thought speculates that grass eating may be a sign of psychological imbalance. There is no concrete proof to endorse this view. There may be some instances in which dogs having anxiety problems turn to grass eating as a compulsive behaviour. If a dog shows an evidence of extreme anxiety around the time of his grass eating, this may be a probable explanation as to cope up anxiety, many different forms of activities may be taken up by dogs. But all dogs showing grass eating behaviour may not be psychologically stressed.
Theory of food craving: Dogs may eat grass to satisfy their strange non-food cravings. In humans, pica can derive peoples to eat non-edible items. Mineral deficiency is accredited for such behaviour. Many veterinarians think that dogs turn out to grass eating for similar reasons. It appears that dogs try to supplement their dietary requirements specially fibre by turning to grass eating.
Theory of boredom: According to some people, dogs may chew on grass when they are bored. Actually the exact reason that prompts dogs to eat grass is not known–and it may even vary from dog to dog. Dog is simply taking part in the forbidden behaviour as a means to seek attention. Dogs not provided with enough interaction and exercise may try to gain the attention and interaction with the pet parent through engaging with forbidden behaviour. If a dog eats safe grass and shows no other signs of illness, there is little cause for concern. In such cases, involve the dog in physical and mental exercises with more interaction.
Theory of relieving gastric discomfort: One of the most common theory behind dog’s grass eating is that it is a means to vomit. But majority of researches have not substantiated that all dogs eating grass do vomit. It has been observed that the dogs who eat grass slowly and rarely vomit afterwards, however dogs eating grass more rapidly may vomit. This has given speculations that it is being done to relieve stomach discomfort. Researches done on canine digestive physiology have revealed that dogs lack an enzyme to break down beta bond of the cellulose, hence there is irritation of gastric mucosa that might lead to vomit when the grass is eaten too rapidly.
Theory of enjoyable change: Another theory says that dogs eat grass because they enjoy it. Actually there is no way to confirm this theory except ruling out other possibilities. If it is true, grass eating will seldom, if ever, will cause vomiting.
Tips to follow

  • Feed a nutritionally balanced diet and offer toys and activities to cope up boredom.
  • Grass eating along with other signs of illness warrants a visit to veterinarian. Simply eating grass is not a cause for concern in every dog.
  • Prevent grass eating at all costs when the grass has been treated with any type of chemical. Pesticides and herbicides are the known leading cause of pet poisonings.
  • When grass eating is the result of natural instinct, dog can easily be trained by the pet parent with treat rewards. When a dog is taken out for a walk or natural call, he is tempted towards grass. Distract him by giving treat rewards for not eating grass. Some dogs prefer positive verbalisations and petting as a reward in place of food treats for desired behaviour.
  • When a dog eats grass and vomits quickly, profusely and repeatedly, it is a cause of concern and needs thorough investigation by a veterinarian.

(Prof Dr JP Varshney, MVSc, PhD (Medicine), Retired Professor, is currently engaged as Senior Consultant (Medicine) at Nandini Veterinary Hospital, Surat).