Why Do Dogs Eat Grass?

Many dogs love to channel their inner cow and graze on grass. Some are even particular about what type of grass they eat. Is this behaviour a sign of a nutritional deficiency or illness and is it safe?

Grass eating is a common behaviour and one I get asked about all the time. Some dogs will indiscriminately eat any grass, some are more selective. My own dog loves the tender young shoots in a particular area of the yard, but ignores all other grass. Mostly we want to know if grass eating is a sign of the dog feeling unwell or if something is missing something from the diet. The truth is no one knows exactly why dogs eat grass, but there are a number of theories.

Aren’t Dogs Carnivores?

This is a popular misconception, dogs are actually omnivores who eat anything, and are known as opportunistic scavengers. Any owner of a Labrador will attest to the adventurous palate of their canine companion. Luckily they also vomit easily and on occasion very vigorously, which is a great survival mechanism for those that really love to eat nasty things. Dogs have essentially evolved alongside humans to live off whatever waste they can manage to acquire. This does not of course mean that all dogs are designed to be walking garbage disposals; on the contrary many have a very delicate stomach.

Vomiting After Grass

Many dogs will eat grass furiously then vomit. If your dog is licking his lips, salivating or swallowing a lot, it could be assign he is feeling nauseous. If he has frequent diarrhoea, is off his food, lethargic or is vomiting more than once a week, see your vet for advice. The vomiting could be a sign of something more serious, or simply a food intolerance or allergy.

Nutrient Deficiency

Another popular theory is that grass eating is associated with a nutritional deficiency, whether that be fibre or a micronutrient. Many dogs, like humans often eat a diet that may not be ideal, particularly those fussy pooches that end up eating lots of meat, but no vegetables. In some cases adding more fibre (in the form of bran, psyllium husks or grated/cooked vegetables) can reduce grass-eating behaviour, or switching to a premium diet. If home-cooking a diet and feeding only this, remember the omnivorous habits of the dog and ensure there is variety. It is estimated you need 50 or so ingredients to get it right, so get some advice from a veterinarian. There are also online services that can help you formulate a diet for your dog.

Is it Safe?

If your dog is eating a large amount of grass, consider what chemicals he might be ingesting. If the grass has been recently sprayed with pesticides, this may be a problem, though usually a large amount must be ingested for a problem to occur, so low levels are most likely fine. Generally if the grass eating behaviour is not associated with signs of nausea or frequent vomiting, and is not obsessive, there is no need to worry.

Compulsive Grass Eating

There are some obsessive compulsive dogs out there, for which grass eating is more than a casual habit. If you have any hint that your dog is suffering from anxiety get some advice from a veterinary behaviourist, and trust your instincts that there could be something else going on.

Final Thought

Grass eating is extremely common and poorly understood. It occurs for a number of reasons, and is only a problem if it is associated with nausea, or anxiety. If not, there is most likely no harm in it and you can let your dog graze away to his heart’s content.