I used to have a friend at the barn who would always feed her horse Sherman the crusts of her grilled cheese. He seemed to love it, and he lived many MANY happy years in retirement despite countless grilled cheese crusts. So, can horses eat cheese? (I mean Sherman lived to be nearly 30 years old!)
Horses should not eat cheese as they are lactose intolerant. Although young foals are potentially able to eat cheese, this is not recommended. Following a foal’s weening, horses are essentially lactose intolerant and feeding them cheese can have serious health implications.
So there you have it – despite Sherman’s longevity, horses are actually lactose intolerant!
I’m going to take a look at what the research says before moving on to all the key facts you need to know about horses, cheese, and lactose in general. I’ll finish with a few more pointers about what horses definitely shouldn’t eat (and some may surprise you).
OK, first for the research…
Research About Horses Eating Cheese
According to a study done on carbohydrate digestion and absorption studies in horses…
“In horses older than three years, lactose did not produce an increase in the plasma glucose levels but induced the passing of soft faeces, indicating that adult horses are lactose intolerant. Horses of all ages could absorb the glucose: galactose mixture without any change in the faeces. The tolerance is due to a failure to hydrolyse lactose and does not involve the monosaccharide transport systems. These findings correspond to the known development pattern of brush border lactase activity in the equine small intestine.”[Source]
In English, please?
What is Lactose – The Easy Version
Lactose is a type of disaccharide which is a sugar that is composed of both galactose and glucose (two monosaccharide sugars).
This sugar is present in most dairy products.
Lactose in particular makes up 2-8 % of milk. So remember that anything that ends in “ose” is a sugar.
In order to digest lactose, the body needs to break down this sugar into its smaller subunits. Humans do this by an enzyme known as lactase.
An enzyme in simple terms is a substance that occurs naturally in the body. It helps break down big molecules in a series of chemical reactions. Enzymes can cause these reactions without being affected in the process.
So remember that anything that ends in “ase” is an enzyme. [Source]
Horses Are NOT Lactose Intolerant From Birth
Lactase is needed for our bodies to happily digest and enjoy most dairy products.
Like all other creatures, lactase is needed to break down lactose into smaller units to be digested and used by the body. Then the small intestine will absorb these “simpler” sugar molecules.
Young foals do have the ability to produce lactase and break down the lactose in their mother’s milk. As they age and are weaned, the body naturally slows and reduces the production of the lactase enzyme to a point where it’s virtually undetectable.
This is most likely due to the body’s reduced and eventual discontinuation of primarily nursing as a food source [Source].
It’s at this point horses become essentially lactose intolerant.
Symptoms of Lactose Intolerance in Horses
Much like what humans experience, ingestion of products with lactose will cause multiple gastrointestinal side effects.
In horses, it mainly manifests as diarrhea and colic.
This of course will vary depending on the amount of lactose they have ingested. Some of the signs may be more subtle like bloating and lethargy.
These symptoms are due to the lactose traveling through the digestive tract unchanged into its smaller byproducts.
This big molecule causes bacteria to collect and causes the intestine to retain water and electrolytes. This leads to watery stool or overly loose or soft stools plus overall gastric and intestinal irritation.
Of course, these symptoms can be due to a multitude of reasons, but if you’re suspecting your horse has ingested lactose (or you know they have) these are the signs and symptoms to look for [Source].
If your horse is exhibiting any of these signs, a call to your vet is warranted regardless if you think lactose is the culprit or not.
If you suspect your horse may have ingested a product with lactose, you should call your vet who may want to come to pay you a visit or may just give you some guidance on how to treat their symptoms and what to watch for.
Lactose Intolerance in Foals
Foals normally should have the lactase enzyme to digest their mother’s milk until they are old enough to be weaned.
In some rare cases, some foals have a problem with secreting the enzyme and are unable to break down the lactose in the mother’s milk.
If this occurs, you will see similar symptoms that you would see in an adult horse such as gastrointestinal upset as well as weight loss or overall lack of growth (both weight and height).
Some foals are born with this abnormality and it will be quite apparent once they begin nursing that there is something wrong. This could be detrimental to their health, especially in the first days of life.
Lack of enzyme activity could also be triggered by other health problems like parasites or bacterial infections. [Source]
Diagnosing Lactose Intolerance in Foals
For the most part, no real test needs to be done.
If the symptoms are noticed after the timing of nursing, chances are that the foal is having a problem digesting mom’s milk.
If there is a question as to what the cause is, lactose can be administered orally and a blood test can be done to see if the lactase activity is appropriate. This test can be complicated as it requires the foals to fast.
Then once the lactose is administered, blood needs to be drawn every 30 minutes over a 3 – 4 hours period immediately after the lactose was given. [Source]
How to Treat Lactose Intolerance in Foals
In some circumstances, exogenous lactase enzyme – or in simple terms, lactase given from outside the body versus lactase made inside the body – can be given and the foal’s symptoms should improve and/or completely resolve.
In other cases, a different type of diet may need to be provided like soy products or a milk replacement (made for foals) that does not contain lactose.
Additionally, the foal could be weaned early and could be supplemented with small quantities of grain or good-quality hay.
All interventions should be under the guidance of a veterinarian, who may even consult a specialist and/or a dietitian. [Source]
What You Shouldn’t Feed Your Horse
Unfortunately, there are many foods that you shouldn’t feed your horse. As far as cheese is concerned, most cheeses possess lactose – which is a big NO on the list of snacks to feed your horse. However, there are many foods that have lactose in them.
Here are a few:
- Ice Cream
- Breakfast Cereals
These are just some of the major hitters in a VERY VERY long list of foods. Some being like mashed potatoes and Mac and cheese that would probably be unlikely to find their way to the barn.
Just because the food may not be exactly one of these, this may be one of many ingredients in the food. For humans who are lactose intolerant, there are many substitutions and lactose-free options for people who still wish to indulge in pizza and ice cream [Source].
For horses, there are not many reasons to feed these lactose-containing products and thus the best recommendation would be to steer clear of foods containing lactose.
So What About Sherman’s Grilled Cheese Habit?
After doing more research on cheese and now knowing it’s definitely not recommended for horses I think back to Sherman. Sherman happily gobbled the cheese-filled crusts and never seems to be in distress or bothered by it.
When I think back, it’s very possible that Sherman may have had a few bouts of diarrhea that were chalked up to other things like stress or a change in his feed.
When I think more about Sherman, I do realize that his favorite grilled cheese buddy did eventually become a vegan, so I assume the grilled cheese treats stopped – or she simply continued to share her crusts with a vegan-free cheese (lactose-free option).
The big picture here is cheese is not recommended as a tasty snack for horses. If your horse accidentally steals a Cheezit from your hand, you probably will just have a good laugh and remember to hide your precious snacks. However, if you’d like to share an entire wheel of cheese with your horse as an after-show snack, you should strongly reconsider!!
Carbohydrates. PC. (n.d.). https://pchorse.se/index.php/en/articles/digestion/digestion-carbonhydrate.
Carbohydrate digestion and absorption studies in the horse. Research in veterinary science. https://pubmed.ncbi.nlm.nih.gov/1118666/.
Miscellaneous Causes of Diarrhea in Foals – Digestive System. Merck Veterinary Manual. https://www.merckvetmanual.com/digestive-system/intestinal-diseases-in-horses-and-foals/miscellaneous-causes-of-diarrhea-in-foals.
What is lactose? Green Valley Creamery. https://greenvalleylactosefree.com/lactose-intolerance/resources/what-is-lactose.