Dogs explore the world with their noses and mouths. Pica is the medical disorder of eating non-nutritive substances such as grass, metal, clay, coal, sand, dirt, soil, faeces, chalk and pens to name a few! Dogs are remarkably flexible in their tastes; they'll polish off a bowl of dog food and then continue to see if there is anything else that is worth stealing! For dogs, grass could just be seen as attractive, sweet-smelling and accessible; so why not eat it?!
Dogs have been eating grass for thousands or even tens of thousands of years, and there's no evidence that this pica behaviour is bad for them. These are the theories as to why dogs indulge:
1. Wild dogs, wolves and foxes will eat all of an animal which they catch while hunting. Dogs are omnivores, eating meat as well as plants. They don't need grassy nutrients anymore because most commercial dog foods are nutritionally complete, however dogs are not nutritionists and they don't know that they've already received their vitamin or mineral requirements from their food. Their instincts tell them that grass is good, so they eat it.
2. Dogs are also said to eat grass to make themselves sick if they have a stomach irritation. Even dogs who usually don't eat grass will head straight for the nearest patch when they're feeling sick. They'll gobble a few mouthfuls, retch, and then throw up, or at least try to. We still aren't sure if dogs eat grass because their stomachs are upset or if their stomachs get upset after they eat grass. However, many veterinarians suspect it's the former. The stomach contains neuro-receptors that respond to what dogs ingest, they react to acidity, chemical content, and textures. The texture of the grass has a tickle effect on the stomach, which may induce vomiting. Dogs who are sick, often appear almost desperate for grass, they don't chew it carefully, they gobble it!
However, evidence suggests that most dogs that eat grass aren't unwell beforehand, or at least they don't appear so. In fact, according to their owners, fewer than 10% of dogs seem to be ill before eating grass and grass-eating doesn't usually lead to throwing up --in a recent survey less than 25% of dogs that were found to eat grass were sick after grazing.
3. Therefore, another theory is that dogs may eat grass to settle their stomachs if they are suffering from stomach pains. It is speculated that dogs might eat grass to improve digestion, to treat intestinal worms, or to fulfil a nutritional need, such as higher dietary fibre. Dogs that chew grass thoroughly and slowly, reduce the tickling effect on the stomach, enabling them to eat it without getting sick.
4. Some people believe it is a simple behavioural habit or boredom alleviator, especially when practiced by puppies and younger dogs. If you suspect your dog is eating grass because he is bored, ensure he is getting enough exercise and engage him in some fun activities, such as ball throwing, training or chase!
5. It is possible that dogs simply like the taste and even if you're feeding your dog well, he might still fancy some greens! Dogs have survived by scavenging. They simply weren't fussy, and dogs today haven't got any fussier. They are predisposed to like just about everything! In addition, there's some evidence that dogs get cravings for certain foods and for many dogs, a mouthful of grass clearly tastes great. If your dog likes to eats grass, try supplementing their diet by adding some grated green vegetables such as broccoli or green beans into their food.
These theories highlight that we don't entirely understand why dogs eat grass. Experts agree that grazing itself isn't harmful; the danger is in the form insecticides, herbicides and pesticides used on lawns that are toxic if ingested. Fertilisers are often one of the top 10 causes of pet poisoning in the UK, so keep an eye on how much your dog is helping you to keep the lawn at bay!