Our ten-year-old Labrador has recently developed a habit of eating long blades of grass while we are out walking. Although he has occasionally done this in the past, it has become more frequent lately, which has led us to wonder if this has anything to do with his recently diagnosed illness. Why do dogs eat grass?
Sadly, our boy has been diagnosed with Urinary Tract Cancer, seemingly contributing to intermittent constipation. Is he eating more grass to help with the constipation? We wondered about that. When I asked my Vet about this, he stated that he believes it is not particularly relevant and probably just a natural habit.
I decided to do some research myself. I hope this helps a Doggie owner out.
1. The Standard Theory of Grass Eating in Dogs
This is a theory around a long-held belief that Dogs Eat Grass Because they feel unwell or poorly.
A possibility is that dogs eat grass to alleviate digestion issues such as an upset stomach or constipation.
The grass could potentially help them vomit or stimulate bowel movements, usually resulting (you would think) in making them feel better. This theory seems to make sense for our Labrador. As I said, he has always had the odd nibble, but I can not help but feel that he is currently far more determined than ever to have a good munch.
The Findings of Dr Benjamin L Hart’s Survey – Pet Dogs and Grass Eating Habits based in California USA.
An interesting questionnaire-style study completed by Veterinarian Benjamin L. Hart, DVM, PhD, DACVB found little evidence of dogs eating grass to induce vomiting or because they felt unwell.
Dr Hart and his team conducted a sizeable Web-based survey, which received over 3,000 responses from owners of dogs. The survey asked about the dogs’ plant-eating habits, diet, and other factors such as sex, breed and age. The study excluded responses from owners who spent less than six hours a day with their dogs and those whose dogs appeared only to chew but not ingest plants, and it was eventually narrowed to 1,571 usable participants.
The study’s findings revealed that
- 68% of the respondents reported their dogs ingesting plants daily or weekly. Additionally,
- 8% of respondents mentioned their dogs frequently showed signs of illness before eating plants,
- While 22% reported their dogs regularly vomiting afterwards.
The study also found that younger dogs consumed plants more frequently than older ones and were less likely to appear unwell beforehand or to vomit afterwards.
This study concluded, therefore, that contrary to the common perception that eating grass is associated with signs of illness and vomiting, grass eating is a typical behaviour in normal dogs and is not necessarily related to illness.
The study also revealed that dogs do not regularly vomit after eating grass. Incidentally, vomiting appears to be a side effect of plant-eating rather than a direct cause.
If Wild Dogs Eat Grass – does this mean that it is a natural behaviour?
While there is very little in the way of studies on the stomach contents or eating habits of domestic dogs, Hart’s findings are supported by a study of wild dogs known to eat grass and plants.
In 2004, a study found that wolves’ stomach contents contained an average of 10% berries and vegetation, very much suggesting that consuming vegetation is a natural ecological behaviour.
(Andersone Z, Ozolins J. Food habits of wolves Canis lupus in Latvia. Acta Theriologic 2004; 49:357-367.)
The Taste and Texture Theory of Grass Eating in Pets.
It is believed that dogs may like the taste or texture of grass. The fresh scent and satisfying crunch could be appealing to them, or maybe they enjoy the sensation of cold, wet raindrops on the grass. Based on my experience over the past decade, I can say that our dog tends to munch more when the grass is cold and wet. After speaking to friends who have various pet dog breeds, I found that they agree with this observation. One friend shared that her Cavoodle seems to enjoy eating so much that he will eat anything, especially when it is wet, and he can also get a quick drink.
2. Pet Dog Grass Consumption: Nutritional Motivation or Quirky Behavior?”
Some researchers also believe dogs eat grass to supplement their diet with essential nutrients.
Exploring the nutritional content of grass prompts the question: Is this what entices our beloved pet dogs to graze? Some researchers propose that dogs consume grass to supplement their diet with essential nutrients. Drawing parallels to the natural behaviour of wild animals ingesting the stomach contents of their prey, dogs might mimic this by directly eating vegetation gaining fibre, vitamins, and minerals that could enhance their health.
Do Dogs Eat Grass to Boost Fibre Intake?
However, the nutritional value of grass is inherently limited, leading to a puzzle: Do dogs eat grass to increase fibre intake? I found two completely conflicting studies on fibre as a possible reason for eating grass. The conflicting findings from two studies on fibre point to a need for further research.
“Debunking the Notion: Dogs Don’t Seek Nutrients from Grass?
Given that Dr Harts’s study (above) looked at the dogs’ diets as one of the factors of the study, you would have expected to see a significant difference in levels of grass eating depending on the food a dog was being fed. For example, if the diet was low fibre, one might expect to see a correlation of increased grass eating. This suggests that dogs may not actively seek fibre from grass to address dietary deficiencies, but doesn’t explain that many pet owners see an increase in this grass-eating activity when their dog is struggling to go to the toilet.
“Unveiling a Positive Case Study: High-Fibre Diets Shown to Influence Plant-Eating Behaviour.
A paper written in Japan for the Journal of Veterinary Medical Science presented a case of a Poodle exhibiting long-term plant-eating behaviour. The dog’s persistent plant consumption and vomiting issues spanned seven years, leading to a diagnosis of a plant-eating problem. In this case, a high-fibre diet was recommended, resulting in a positive response, indicating a potential link between dietary needs and grass consumption.
- The case was written regarding an 11-year-old male Miniature Poodle dog,
- The Poodle had been referred to a Vet due to a persistent issue of eating plants and subsequently vomiting for seven years.
- During walks, the dog would eat grass and then vomit.
- Medical examinations did not reveal any abnormal findings.
- The Poodle was diagnosed with a plant-eating problem.
- It was theorised that the dog was eating plants to satisfy a dietary deficiency or relieve digestive issues.
- The owner was requested to discontinue the previous diet and start a high-fibre diet.
During a follow-up, the owner reported that the dog had stopped eating plants and had not vomited for three days after the initial dietary change. The dog has been free of any clinical symptoms for the past 13 months. This clinical finding suggests that a deficient diet, especially one lacking in fibre, may be related to plant-eating behaviour in dogs.
“The Canine Diet Conundrum: More Questions Than Answers”
This intriguing contradiction highlights the complexity of our pet dogs’ dietary behaviour, leaving us with more questions than answers in exploring why our furry friends indulge in grass-eating behaviour.
3. The Biological Purpose Theory – Do Dogs Eat Grass Because they have worms?
More studies are needed, but plant-eating may serve a biological purpose. One explanation is that plant-eating played a role in the ongoing purging of intestinal parasites (nematodes) in wild canid and felid ancestors (who were constantly exposed to intestinal parasites).
Therefore, grass or plant-eating by pet dogs is generally unassociated with illness or a dietary deficiency. It more likely reflects an innate predisposition inherited from wild canine ancestors.
Conclusion
It seems that the Jury is still out on whether there is any real purpose in pet dogs eating grass.
The experts do seem to agree that it is not usually a sign of a dog being particularly unwell. If your dog appears to be eating more grass than usual and you are concerned that he is not feeling well, it may be a good idea to consider changing his food or snacks (after all, you know him better than anyone). Our Lab did particularly well for years on Grain Free Foods. We found that too much grain irritated his stomach and his skin.
It is, however, essential to remember that eating grass can potentially harm dogs. Grass may contain harmful chemicals, bait or pesticides, which can be highly toxic if ingested. Additionally, some dogs may be allergic to particular grass or plants, which can cause vomiting or other unpleasant symptoms. If your dog frequently eats grass or has suddenly started eating it more regularly, speaking to your vet to rule out any underlying health issues is still a good idea.
In the comments sections below, I would love to hear your thoughts and experiences in this area.
Additional Information and Disclaimer
Disclaimer: This article has been written on my own interest and assessment of the research in this field. Whilst every effort has been made to ensure its accuracy, I am not a qualified Vet. Please seek professional advice.
References:
- https://www.researchgate.net/publication/342831331_Beynen_AC_2020_Diet_and_grass_eating_in_dogs
- https://www.researchgate.net/publication/251345024_Food_habits_of_wolves_Canis_lupus_in_Latvia
- https://www.researchgate.net/publication/288656215_Why_do_dogs_and_cats_eat_grass
- https://www.jstage.jst.go.jp/article/jvms/69/7/69_7_779/_article/-char/ja/
