You’re probably aware that chocolate can be poisonous to dogs and cats. The reason chocolate is toxic to many pets is it contains caffeine and theobromine. Rats are very similar to humans, though, and process theobromine just as well as we do! That doesn’t mean chocolate is necessarily great for rats.
Rats love to eat and they’re prone to obesity and the health issues that come with it. Chocolate is fine on occasion, but it’s not the best treat to give rats on a regular basis.
Here’s what you should know about rats eating chocolate, how much is safe, and the best type of chocolate to give rats.
Can Rats Eat Chocolate?
Chocolate is dangerous for cats and dogs due to theobromine and caffeine, two compounds that humans can more easily digest and excrete. Rats have a very similar ability to digest these compounds which makes chocolate as toxic to them as it is to us.
Chocolate isn’t toxic to rats in moderate amounts but, like us, a very large amount can be deadly!
Rats can definitely enjoy chocolate as a treat, but it’s best to give them only small amounts because, theobromine aside, chocolate is still high in calories and fat – especially for a rat.
Theobromine Toxicity: How Much Theobromine Is Toxic to Rats?
Theobromine or xantheose is a bitter-tasting alkaloid chemical found in cacao beans and chocolate. It’s also extracted and used to synthesize caffeine, and it’s a metabolite of caffeine. The human body breaks caffeine down into about 84% paraxanthine, 12% theobromine, and 4% theophylline.
Theobromine and caffeine are both methylxanthine alkaloids that humans can more easily digest and excrete than other animals. Theobromine is what makes chocolate poisonous to dogs and some other animals.
Even in humans, too much theobromine and/or caffeine can be toxic. In humans, the LD50 of theobromine, or the median lethal dose that kills 50% of people, is 1,000 mg/kg of body weight (454 mg/lb). By comparison, the LD50 for dogs is 100 to 500 mg/kg of body weight (45 to 227 mg/lb).
The median lethal dose of theobromine in rats is about 1,000 mg/kg of body weight – the same as humans.
So, how much theobromine is in chocolate? It depends on the type of chocolate. The more processed the chocolate, the smaller the amount of theobromine tends to be. Milk chocolate has less theobromine than dark chocolate, for example, and white chocolate has the least amount.
The average weight of an adult rat is 350 to 650 grams (0.8 to 1.4 lbs). Male rats usually weigh more than female rats. That means the median lethal dose of theobromine is 350 to 650 mg for a rat.
Theobromine in Chocolate Here is the average amount of theobromine in different types of chocolate. | |
Type of Chocolate | Average Theobromine Per Ounce |
Baking chocolate | 390 mg |
Dark chocolate (70-85% cacao) | 228 mg |
Dark chocolate (60-69% cacao) | 179 mg |
Semisweet chocolate chips | 150 mg |
Milk chocolate | 44 mg |
White chocolate | 0.25 mg |
To put this in perspective, a whole standard Hershey’s bar is 1.5 ounces with 66 mg of theobromine. Each of the 12 segments (officially called a “pip”) is just 0.126 ounces (5.5 mg theobromine). A Ghirardelli dark chocolate (72% cacao) bar is 3.5 ounces with about 798 mg of theobromine total.
Rats have about the same ability to process theobromine as humans, but you should still be careful and make sure your rats don’t get too much! There have been limited studies on theobromine toxicity in animals, but research has found a high dose of 250 to 350 mg/kg body weight in mature rats can lead to thymic atrophy or shrinking of the thymus. This can damage your rat’s immune system. In hamsters and mice, much larger doses were necessary to cause this damage to the thymus. When pregnant rats were fed a daily diet containing 53 or 99 mg/kg daily theobromine, offspring had a slightly lower birth weight.
Male rats fed very high doses of theobromine (500 mg/kg daily for about a week) are at a particular risk of sterility caused by damage to cells in the testes.
Is Chocolate Bad for Rats?
Rats can digest theobromine and caffeine as well as humans can. Now that you know chocolate doesn’t kill rats, it still leaves another important question: should rats eat chocolate or is it unhealthy for them?
Rats are quite small and it’s easy to vastly exceed their caloric needs with human food. A rat needs about 60 calories per day. A single square of Ghirardelli dark chocolate is 66.7 calories. One of the pips (small rectangles) of a Hershey’s bar has about 18 calories.
Chocolate isn’t recommended as a regular treat for rats because it’s high in fat and sugar. Even a relatively small amount can account for almost a full days’ worth of calories – it would be similar to a person having a large ice cream sundae. It’s easy for rats to become obese and suffer a range of health effects if they’re given too much food high in fat and sugar.
With that said, it’s fine to occasionally give your rats a bit of chocolate as a special treat!
It hasn’t been well studied, but some of the health benefits of chocolate, and specifically theobromine, may also apply to rats. Theobromine is a bronchodilator which means it helps open the airways, relaxes the muscles of the lungs, and makes it easier to breathe. Research indicates it can be helpful in relieving symptoms of asthma and respiratory tract issues.
Rats have very sensitive respiratory systems and respiratory infections and diseases are common. If your rat has symptoms of a respiratory infection, it may be beneficial to give them a bit of dark chocolate or cacao nibs every day as a treat before you can see the vet or while they’re being treated.
Last update on 2025-09-06 / Affiliate links / Images from Amazon Product Advertising API
Another study found that compounds in cacao, the unprocessed or raw beans from which cocoa and chocolate are made, can prevent rats from developing diabetes-related cataracts.
Yet other studies have found additional possible health benefits of cacao in humans and rats, including antioxidant effects and a reduced risk of cardiovascular disease.
If you want to give your rats chocolate, dark chocolate or cacao nibs are the best option. It’s a bit higher in calories per gram, but it’s lower in fat and sugar than milk chocolate and white chocolate.
Do Rats Like Chocolate?
Absolutely! I haven’t met a rat that doesn’t like chocolate, although they aren’t the pickiest eaters. Dark chocolate doesn’t seem to be as exciting as milk chocolate, but they still love it. I give my rats cacao nibs as an occasional treat and when they have respiratory problems.
Can Rats Have Dark Chocolate?
If you’re going to give your rats the occasional bit of chocolate as a treat, dark chocolate or cacao nibs are the best choices for rats. With dogs, dark chocolate and cacao nibs are the worst kind of chocolate because they’re the highest in theobromine and caffeine, but rats can tolerate them as well as humans and benefit from the lower amounts of fat and sugar.
The Bottom Line: Can Rats Eat Chocolate?
Rats can have chocolate as long as you don’t get them too much or offer chocolate too often. The fat and sugar in chocolate is a much bigger concern than caffeine and theobromine which are the compounds that make chocolate toxic to dogs and cats.
Cacao nibs and dark chocolate for rats are recommended as an infrequent treat or to help relieve symptoms of respiratory illness. In fact, it’s a good idea to keep some cacao nibs in a first aid kit for your rats just in case you notice respiratory symptoms to help them breathe until they can get treatment.
Last update on 2025-09-06 / Affiliate links / Images from Amazon Product Advertising API
