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Gobbling the green: Should dogs and cats eat grass?
By Dr. Narda Robinson
June 4, 2010
Is grass-eating a normal, natural activity for dogs and cats, or a health risk?
The other day, I heard a client being advised not to let her cat eat grass, because when he does, he vomits. As a “natural medicine” vet, this upset me at first. Why impede an individual’s normal, innate impulse to consume greenery, especially if they are ingesting it for health purposes?
After all, I reasoned, animals in the wild self-medicate by seeking certain plants and soils to treat and prevent disease. I tend to trust their instincts. If they do vomit, perhaps they could select a less troublesome site than the Tibetan rug in the living room, but other than that, I support their grass consumption.
Then the skeptic in me begins asking questions. Can I back my recommendations with facts? Maybe there is a problem with dogs or cats consuming greens that I haven’t discovered.
Clearly it was time to dig into the medical literature and see what science had to say.
I found no evidence that grass per se is detrimental for either dogs’ or cats’ health, although obviously fertilizer, herbicides, pesticides, and other contaminants such as parasites on the lawn could pose dangers.
I can also envision grass awns (seeds) entering the oro-nasal cavity and becoming a foreign body on rare occasions. Or a plant could look like grass but be poisonous. While cats are picky in the blades they opt to eat, they are not infallible in their selections — my cat Frankie sometimes starts to takes a nibble from a day lily leaf until I whisk him away. Lilies, unfortunately, are highly toxic to cats.
On the health benefits of grass-eating, I did discover a new study that explored whether dogs with diarrhea would alter grass eating behavior. Researchers fed dogs in one group a standard diet laced with a substance (fructo-oligosaccharide) that would temporarily induce diarrhea; dogs in the other group were spared this ingredient.
As it turned out, dogs with experimentally-caused loose stools spent significantly less time eating either of the grasses made available to them than did those with normal stools.
It makes sense to me that dogs would prefer to take in less plant material if their intestinal transit time was already too fast; I’d much rather have a soy chai and saltines if I was similarly stricken, and skip the tossed salad. Perhaps a better question to answer is whether dogs with nausea or constipation might increase their grass intake to alleviate their distress. This study showed that dogs (presumably without nausea) only vomited two times out of the 374 grass-eating events observed.
Far and away, the biggest benefit of grass-eating stems from its fiber content. Dogs that crave grass and consume it on a daily basis are likely telling us that their diets lack sufficient fiber. It is important not to mischaracterize this call for help as a behavioral abnormality! If they cannot satisfy their need for fiber from nontoxic sources, they may turn to houseplants, like a Dieffenbachia, which can be fatal.
Nutrition studies support high protein, high fiber diets for their ability to improve weight loss and satiety in overweight dogs. More fiber in the diet can mean better blood sugar control in overweight dogs with diabetes.
However, science also shows that a diet high in fiber and moderate in carbohydrates and fat is not recommended for thin diabetic dogs because it can lead to too much weight loss.
Thankfully, more pet foods companies are adding fiber in the form of psyllium, soybean hulls, and even peanut shells, though I would prefer to see organic veggies on a label and not conventionally-produced peanut husks.
One final note for cat-lovers. I’ve also run across folks who won’t let their cats eat not only grass but also catnip, fearing that they will become addicts. Not so. As with grass, catnip provides fiber and nutrients beneficial for digestion. Catnip tea for humans has a long history as a folk cure for stress, colic, pain, sore throats, and sinusitis. The volatile oils in catnip produce a short-lasting euphoria, and poisoning from the fresh plant is nearly impossible. If the fiber in catnip normalizes digestive motility, and the psychoactive agents in catnip help cats relax, we are much more likely to have a happy, healthy cat.
You want citations? They’re after the jump!
[1] McKenzie SJ, Brown WY, and Price IR. Reduction in grass eating behaviours in the domestic dog, Canis familiaris, in response to a mild gastrointestinal disturbance. Applied Animal Behaviour Science. 2010;123(1/3):51-55.
[2] Kang B-T, Jung D-I, Yoo J-H, et al. A high fiber diet responsive case in a Poodle dog with long-term plant eating behavior. J Vet Med Sci. 2007;69(7):779-782.
[3] Loretti AP, da Silva Ilha MR, and Rebeiro RES. Accidental fatal poisoning of a dog by Dieffenbachia picta (dumb cane). Vet Hum Toxicol. 2003;45(5):233-239.
[4] German AJ, Holden SL, Bissot T, et al. A high protein high fibre diet improves weight loss in obese dogs. The Veterinary Journal. 2010;183:294-297.
[5] Weber M, Bissot T, Servet E, et al. A high-protein, high-fiber diet designed for weight loss improves satiety in dogs. J Vet Intern Med. 2007;21:1203-1208.
[6] Laflamme DP. Nutrition for aging cats and dogs and the importance of body condition. Vet Clin Small Anim. 205;35:713-742.
[7] Fleeman LM, Rand JS, and Markwell PJ. Lack of advantage of high-fibre, moderate-carbohydrate diets in dogs with stabilized diabetes. Journal of Small Animal Practice. 2009;50:604-614.
[8] Hornfeldt CS. Nepeta cataria (Catnip) “poisoning” in cats. Veterinary Practice STAFF. 1994;6(5):1,7.
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Excellent. Thanks.
Comment by LynnO — June 4, 2010 @ 1:09 pm
Digging out my catnip from the overloaded fridge, daughter, and goin’ to give my cats each a healthy dose.
Comment by Evelyn — June 4, 2010 @ 1:12 pm
Evelyn maybe you can get your daughter, the fabulous Dr. Robinson, to write LOTS over the summer.
Use your mother’s guilt on her. :)
Comment by Gina Spadafori — June 4, 2010 @ 1:25 pm
Can’t do that now that you “let the cat out of the bag”, Gina!
‘Tis a shame catnip doesn’t work on humans like it does on cats. I could have tried that to lure her into writing more.
Comment by Evelyn — June 4, 2010 @ 1:40 pm
Dr. Narda, I’m having trouble determining whether daylilies are indeed toxic.
All sources agree that true lilies (genus lilium) are toxic to everybody.
There are all sorts of disputes about daylilies (genus hemerocallis). Most agree that humans can eat them. Some say that they are toxic to cats and dogs, or to cats only. Others that they just got put on toxic lists because of confusion with true lilies.
Inquiring minds — especially inquiring minds with big patches of daylilies by the barn — want to know!
Comment by H. Houlahan — June 4, 2010 @ 1:59 pm
Aha!
Actually, some people reportedly do smoke catnip and report a high like marijuana. I wouldn’t know anything about that.
Comment by Dr. Narda — June 4, 2010 @ 2:02 pm
I’m glad someone finally looked this up! I don’t know how the fiber in the diet squares up with the “all-protein” diet that I’ve also read about, but my cats are glad I won’t take away their cat grass on the sunny windowsill. Catnip is a native wild plant here and I always bring some long stems home after helping my local conservation groups keep their sites in order—organically, of course.
I consider these to be an important way to enhance the environment for indoor cats. Chlorophyll is a good thing in the diet too along with all those fresh vitamins and minerals just ready to be digested.
Mine rarely vomit it back up, and I think sometimes animals do because they don’t eat it regularly and their body finds it difficult to digest the first time or two.
Comment by Bernadette — June 4, 2010 @ 2:03 pm
Thanks for the question about day lilies. I’ll double check!
Comment by Dr. Narda — June 4, 2010 @ 2:03 pm
We call our girls the cowdogs because they would be happy to graze on grass all day. They don’t throw it up, either. I think they just like it.
Comment by Kim Thornton — June 4, 2010 @ 2:11 pm
“Day lily (Hemerocallis spp). The entire plant is toxic to cats. Ingestion of this toxin results in non-specific signs followed by acute renal failure (usually anuric) within 24 to 48 hours. It is unkonwn whether dogs or birds are sensitive to the toxin found in these plants. No specific antidote.” Handbook of Small Animal Toxicology and Poisonings. Gfeller et al. Mosby, 2004.
Comment by Dr. Narda — June 4, 2010 @ 2:21 pm
Also “A report on cases of plant poisoning covering the year from 1995 to year 2000 among Brazilian cats was presented. Emphasis of the report focused on the clinical aspects as well as necropsy findings in cats poisoned by Day Lily Hemerocallis spp.; Hemerocallidaceae in the southern regions of Brazil.”
Poisoning by day lily (Hemerocallis sp.; Hemerocallidaceae) in Brazilian cats.
In: Poisonous plants: global research and solutions Wallingford: CABI, 2007, 46-49.
Comment by Dr. Narda — June 4, 2010 @ 2:22 pm
For more about day lilies, this time in sheep:
Pathogenesis of ‘Hemerocallis blindness’ in sheep.
Author(s):Barlow, R. M. et al.
Source: Neuropathology and Applied Neurobiology 15 (6), 1989, 592
Source Note: Proceedings of the 78th meeting of the British Neuropathological Society 13-14 July 1989
Abstract:Some species of Hemerocallis, the day lily, have flowers regarded as an edible delicacy. The roots are used in Chineses traditional medicine for the treatment of human schistosomiasis, but may produce permanent blindness and slowly resolving paresis or death. The toxic principle is hemerocallin (stypandrol). In a preliminary experiment, the development of the clinical disorder following a single dose was traced from mydriasis through retinal vascular congestion, papilloedema and haemorrhage to retinal detachment. The pathology of the late active and residual stages of intoxication in rats suggested a distinct direct effect on axons, astrocytes and oligodendroglia. Results in sheep, however, are compatible with a less complex primary response.
Who knew that my simple little piece on grass eating in dogs and cats would take us back to the dangers of certain Chinese herbs?
Comment by Dr. Narda — June 4, 2010 @ 2:25 pm
Ahhh! Perfect time to ask a stupid question! I was told years ago that the silica spicules contained in grass blades & stems was what made dogs and cats vomit if they consumed too much too quickly. Dogs and cats are not by nature herbivores, and have neither the complex gut nor the bacteria needed to digest much grass. However, the reason that both persist in eating grass in spite of the risk of losing one’s lunch is because grass contains sugars, the most well known sugar containing grass being sugar cane. So here are the stupid questions: is the vomiting caused by the silica spicules? And are cats & dogs really attracted to the sugars?
Comment by Deb Moulton — June 4, 2010 @ 2:57 pm
Not a stupid question at all, Deb! I’m trying to see if I can find an answer for you, but so far I haven’t found any evidence that anyone has even explored whether dogs and cats vomit because of silica, and whether it’s the sugar in the grass that attracts them.
Cats aren’t known to be sweet-a-holics anyway, but some have developed a taste for carbs. Other plausible reasons considered about why they like this blade but not that one could be a differential in the amount of certain minerals or other nutrients in one group versus another.
Comment by Dr. Narda — June 4, 2010 @ 3:21 pm
Glad to see this…my two goldens eat grass daily..and in fact are constantly trying to get the grass on the other side of the fence..hmm…maybe that is where they got that “grass in greener on the other side”…musta been a golden owner…
Comment by Carol V — June 4, 2010 @ 5:00 pm
My vet tells me the grass is similar to the taste of fresh asparagus for dogs.
Comment by VJ — June 4, 2010 @ 5:33 pm
My vet tells me the grass is similar to the taste of fresh asparagus for dogs.
Comment by VJ — June 4, 2010
Assuming it’s in any way possible to determine what anything tastes like to a dog … My weird brain immediately wants to know: If dogs eat grass does their pee smell like grass?
Someone get back to me on this, K?
Comment by Gina Spadafori — June 4, 2010 @ 6:05 pm
VJ, did you know that dog urine apparently is affected by the sugars much the same way human urine is? This is based solely on anecdotal evidence btw and based on my experiences with my previous puppy who I was introducing to fresh veggie snacks/rewards at the time. My dogs all love both fresh and cooked aspargus although it’s not necessary for them to have hollandaise sauce on their spears.
Dr. Narda, if you find out anything, I will be delighted to read what you have discovered!
Comment by Deb Moulton — June 4, 2010 @ 6:07 pm
Who knew that my simple little piece on grass eating in dogs and cats would take us back to the dangers of certain Chinese herbs?
I was thinking much the same thing as I read through your answers. Thanks so much for that!
(My barn cats are canny critters, and I’ve never observed them snacking on daylilies. They’ve got lots of other salad fixins available to them, to dress out a main dish of decapitated voles.)
I often have headdesk moments trying to convince people that medicinal herbs that WORK are not necessarily 100% safe or consequence-free.
“Natural” does not mean “safe in any quantity and in any combination with anything else.” Cyanide is a natural botanical.
Comment by H. Houlahan — June 4, 2010 @ 8:18 pm
“Cyanide is a natural botanical.”
As are strychnine and aconite, and both of those are INTENTIONALLY being included in Chinese herbs sold in this country by veterinarians for use in dogs, cats, and horses.
I wrote an article for Veterinary Practice News on this topic concerning the problems caused by undue faith in the safety (and effectiveness) of Chinese products on the part of some college faculty:
http://www.veterinarypracticen.....etour.aspx
Of course, Chinese herbal practitioners generated quite the backlash, as shown in the comments.
Comment by Dr. Narda — June 4, 2010 @ 8:35 pm
I was at a health food store this winter buying wheat grass for my cats. The man that checked me out told me he puts it in a blender and drinks it. Yuk! I’ll take my wheat in bread, thank you.
I did have a cat that shared my asparagus with me whenever I made it—he relished eating the tips and I got the stems. To him it was a “delicacy”.
Comment by Evelyn — June 4, 2010 @ 8:35 pm
I’ve heard that wheat grass juice tastes like drinking the front lawn. Never tried it, but it sure smells freshly mowed.
Comment by Dr. Narda — June 4, 2010 @ 9:02 pm
I like wheat grass juice. At first it does taste pretty odd but if you chase it with orange juice it is strangely addicting.
I don’t have a juicer — you need a heavy-duty machine to process wheat grass.
Instead I bought it frozen into cubes:
http://www.evergreenjuices.com/
I have an elderly rabbit with all sorts of dental problems, so I poured some on her (mashed) food. If it weren’t so expensive I’d give it to her every day.
Comment by Mary Mary — June 5, 2010 @ 4:49 am
Mary Mary,
I wonder if your rabbit would enjoy reconstituted “Critical Care” made by Oxbow, which has timothy grass meal and other fiber sources and vitamins for rabbits.
Comment by Dr. Narda — June 5, 2010 @ 6:16 am
Dr. Narda,
Thanks for the suggestion. Critical Care is indeed great stuff, and a literal lifesaver for anorexic rabbits, but it’s SO expensive!
I work with several shelters and sometimes am able to get a few bags donated. I keep it in the house just in case.
For my “dental” rabbits, I make a soupy mash of Oxbow Bunny Basics T pellets, warm water and pumpkin. Every few days I’ll add in pulverized cilantro or dandelion, + beets. My vet said beets are wonderful for increasing energy (I think it’s from improved oxygen update in red blood cells?)
I have to be careful about the sugar content though, as her gut is pretty sensitive to carbs.
I have two rabbits whose teeth are so maloccluded that they cannot chew hay. It is tough to get enough fiber into them to keep them regular (including the cecotropes they should produce and ingest twice a day).
I spend WAY more time preparing their food than I do my own.
A newer timothy hay rabbit pellet that a lot of my fellow rabbit owners like is Zupreem, which has no soy or wheat. Works wonders on rabbits with loose stools.
Comment by Mary Mary — June 5, 2010 @ 8:19 am
Thanks, Mary! I’ll check into the Zupreem. My bunny clients will be delighted to hear about a good option for feeding rabbits with loose stools.
Comment by Dr. Narda — June 5, 2010 @ 4:35 pm
Dr. Narda,
I’m sure you know this but for those who don’t, any diet change in rabbits has to be done gradually, mixing the new food into the old very slowly over a few weeks.
The Zupreem has been great for rabbits with chronic loose stools, not the cases that just flare up one day and after a bit of oats are back to normal.
Comment by Mary Mary — June 5, 2010 @ 5:19 pm