Post by pea on Apr 1, 2022 4:31:25 GMT -8
Markpd I wrote this article on safe and unsafe foods for gerbils, since a new one was needed, and now my first draft is finished, I would like some feedback. Please let me know any suggestions you have, whether you disagree with any the foods listed as safe or unsafe for any reason, or you think something could be explained better.
Note that if you are viewing this thread on a mobile device, the superscript characters (e.g 1 or a) may show up as normal-sized characters instead of superscript. I have made these italic to differentiate them from the rest of the text to avoid confusion.
Safe foodsThe following foods are widely regarded as safe to feed:
Beetroot a (root and leaves)
Broccoli b (florets, stalk and leaves)
Brussels sprouts b (sprouts, plant leaves and flowers)
Carrot (root and leaves)
Celery (stem and leaves)
Cooked beans and pulses d
Sweet potato (cooked)
Tomato (ripe only, no leaves)
a Beetroot may colour a gerbil’s urine red or pink, which is harmless but could cause alarm!
b Cruciferous vegetables such as broccoli, cauliflower, cabbage and brussels sprouts cause gas and have been reported to cause serious bloating in other animals. Feed in careful moderation, if you feed them at all.
c Parsley may be unsafe for pregnant gerbils. Large amounts of parsley can cause miscarriages in humans and parsley has been used in herbal medicine to induce abortions.1
d Some beans and pulses may also be safe to feed raw, but others are highly toxic. See the section on raw beans below for more information.
Apple (no seeds)
Apricot (not the stone)
Cherries (not the stone)
Peaches (not the stone)
Plum (not the stone)
Other plants, flowers and leaves
Chamomile leaves and stems
Dandelion flowers, leaves or root
Echinacea/coneflower flowers and leaves
Melissa/lemon balm leaves
Raspberry, blueberry, blackberry, gooseberry or mulberry leaves
Redcurrant or blackcurrant leaves
Strawberry flowers and leaves
Sunflower leaves and petals
Wheat, oat or rye grass
Seeds and grains
Milk thistle seeds
Pumpkin or squash seeds
Bread, toast or crackers - no salt, seasoning, margarine or butter
Cereals (cheerios, shreddies etc) - stick to plain, unsweetened varieties
Cheese - hard cheeses such as cheddar are better as they are low in lactose. Avoid blue cheese, mould-ripened cheeses (e.g brie), most soft cheeses and unpasteurised cheeses. Cottage cheese is suitable as it is relatively low in lactose.
Cooked meats and fish, but avoid processed or preserved meats such as bacon, sausage, salami etc.
Dried or live d insects - mealworms, waxworms, morio worms, calci worms, grasshoppers, locusts, crickets
Nuts - peanuts, almonds, cashews, hazelnuts, pecans, pistachios, walnuts, brazil nuts. Be especially moderate with brazil nuts as they are exceptionally high in selenium which can be harmful in overdose.2 Choose unsalted, unseasoned nuts.
Pasta - dry or cooked
d See section below on feeding live insects
Feeding live insects
Gerbils can be fed live insects for extra enrichment but you should bear in mind a few guidelines:
Never feed insects from outside to your gerbils. They may be carrying bacteria or harmful chemicals. Only feed insects sold by a pet shop for animal consumption (or the offspring of these insects if you have bred them yourself at home).
Crickets and locusts should be in proportion to the size of your gerbil. Don’t give a big 6 inch locust to your 8-week-old gerbil. Choose a size your gerbils can easily catch.
Mealworms can be fed live, but morio worms have very strong jaws which could hurt a gerbil. Cut the head off a morio worm before feeding it.
Feed mealworms or other larvae in a bowl because otherwise they will burrow down into the bedding and get lost.
Don’t give crickets or locusts to heavily pregnant gerbils or gerbils with young pups. They may bite hairless pups.
Lily eating a locust
These lists are not necessarily exhaustive so if you’re wondering about a food not on them, ask on the forum for guidance.
This is the short list of foods that are considered unsafe for gerbils. Scroll down for more information on the reasons each food could be unsafe.
Raw potatoes, green potatoes or potatoes that taste bitter
Sprouted sorghum and millet
Most dairy products
Alliums - onion, garlic, leeks, chives
Tomato plants and unripe tomatoes
Avocado - especially the skin, flesh near the pit and unripe avocado
Raw kidney, tepary, butter/lima and winged beans. Also the raw mature seeds of the runner bean plant.
The following foods may not necessarily be poisonous, but they’re a bad idea to feed:
Fried and greasy foods
Foods high in sugar or artificial sweeteners: cake, biscuits/cookies, sweets/candy, chocolate
Very sticky foods such as peanut butter (unless spread thinly on something)
Foods high in salt: pickled foods, processed and preserved meats e.g salami, crisps/chips, salted nuts
In short, if it’s bad for you, it’s probably bad for your gerbils too!
Contrary to common belief, grapes and raisins are completely safe for gerbils, as are dandelions in moderation. There are controversies over citrus fruits, mushrooms, iceberg lettuce and chocolate which you can read more about below.
Grapes and raisins
One of the biggest myths in gerbil keeping is that grapes and raisins are poisonous to gerbils. This idea appears to have originated from the fact that they are poisonous to dogs. In dogs, grapes can cause rapid onset of severe kidney disease. Dogs have different digestive systems to rodents and are more sensitive to various substances such as tartaric acid (a possible cause of canine grape toxicity3) and theobromine. Grapes and raisins are very commonly fed to gerbils, and to other small animals such as hamsters and rats, and a sudden onset of illness shortly afterwards doesn’t appear to have been reported. It is safe to feed your gerbils grapes and raisins, though as usual, everything should be fed in moderation. Raisins are one of the most popular gerbil treats, though as they are very sugary they should be torn in half or even smaller.
(Thanks to markpd for finding the relevant research papers for this topic)
Dandelion has been said to be carcinogenic due to its caffeic acid content. Rats and mice fed a diet containing 2% caffeic acid developed tumours at a significantly higher rate than controls fed 0% caffeic acid.24 However 2% caffeic acid is a huge amount. Assuming a rat eats 10g food per day, this equates to 200mg/day caffeic acid, which is equivalent to approximately 30g dandelions per day.25 This is far more than a rat (or gerbil) could ever eat. Dandelions fed in moderation should not be a problem for most healthy gerbils.
These types of studies are intended to help us understand how diseases and tumours develop, and tend not to be so helpful in directly informing our animal husbandry. The study conditions (i.e in this case the quantity of caffeic acid fed) are simply too exaggerated and too unnatural to produce results that we can reliably apply to our pet care.
Dandelions are a well-known diuretic, so have the potential to cause dehydration if fed in excess. It probably isn’t a good idea to feed them to gerbils already at risk of dehydration, such as those suffering from diarrhoea or kidney disease causing increased urination, or gerbils that are not drinking much.
Citrus fruits tend to be considered unsafe due to the acidity. In reality, most citrus fruits have a similar pH to other commonly fed fruits such as apple or banana. The exceptions are lemon and lime, which are very acidic, and which definitely shouldn’t be fed to gerbils.
Some have concerns that excessively acidic foods may damage gerbils’ teeth. Since gerbils’ teeth are continuously renewed through growth, it seems unlikely that some acidic fruit from time to time would have major implications. A regular diet containing lots of acidic fruit may be a problem. We know that if we eat a lot of acidic fruit, it can make our mouths slightly sore, so the same could happen to gerbils if fruit were fed in excess.
Fruit should not form a large part of your gerbils’ diet, not just because of the acidity, but because of the sugar and water content, and the fact that gerbils do not naturally eat lots of fruit, although they may eat some berries in the wild.
There’s probably no particular reason why gerbils can’t eat a bit of orange, but there’s also no particular reason why they should. Berries tend to be the most nutritionally beneficial of fruits, and they are more likely to feature in a wild gerbil’s diet, so if you want to feed some fruit, consider feeding half a blueberry or cranberry, a piece of raspberry or a goji berry.
Most people avoid feeding mushrooms as they seem a strange thing for a gerbil to eat, and probably not something they would encounter in their natural habitat. However there is really no known reason why non-poisonous mushrooms would be unsafe for gerbils, and some people have fed them to gerbils and hamsters without any reported issues.
If you decide to feed mushrooms, stick to store-bought mushrooms. Even non-poisonous mushrooms can cause digestive issues if fed raw, so they should probably also be cooked before feeding.
Iceberg lettuce has often been said to be unsafe for small animals because it is mostly water, and has little nutritional value. Its inclusion on unsafe food lists (often without any reason given) has caused many misconceptions, with some even claiming it is poisonous for small animals. It is true that iceberg lettuce is around 96% water8 but this is roughly consistent with other vegetables, such as romaine lettuce (95%9), spinach (92%10) and cucumber (95%11) which are all commonly fed to gerbils, and all still less watery than water, which we allow our gerbils free access too.
It’s possible that some gerbils might eat too much iceberg lettuce, ingesting too much water, causing diarrhoea. This could happen with any watery vegetable, and can be easily prevented by feeding vegetables in moderation.
It is also true that compared to other leafy greens, iceberg lettuce does have less nutritional value. The table below compares levels of certain nutrients in iceberg lettuce, as compared to romaine lettuce, kale, pak choy, rocket and spinach:
Iceberg lettuce is the worst source of almost every nutrient compared, among those vegetables being compared. If iceberg lettuce formed a large part of your gerbils’ diet, they could be filling up on water and missing out on other nutrients, so don’t make it a large part of your gerbil’s diet.
Iceberg lettuce isn’t toxic or inherently unsafe for gerbils, it’s just a poor choice of food. There are many more nutritious vegetables your gerbils could be eating. A little bit of iceberg lettuce will do no harm, but ideally, opt for spinach or kale or some other nutritious vegetable instead.
Because chocolate is poisonous to dogs, it’s generally assumed to also be poisonous for gerbils, however this probably isn’t true.
The compound that people are referencing when they say chocolate is toxic is theobromine, Theobromine is actually toxic to all animals and also to humans, but it depends on the dose (this is a vital principle to understand when talking about poisons - the dose makes the poison: all things are poisonous and nothing is poisonous, it all depends on the dose etc) Cats and dogs have a much lower tolerance to theobromine which means they can get very seriously ill after having consumed a smaller amount of chocolate proportional to their weight. Rodents have a tolerance to theobromine more similar to humans15 (although it is worth noting that gerbils specifically have not been studied), which means they would have to eat a similar amount of chocolate proportional to their weight than we would have to eat, before getting symptoms, and that amount is a huge amount. So theobromine is probably not the reason to not feed chocolate, unless you also deny yourself chocolate for the same reason.
More of concern is the sugar, dairy and fat content, plus all the other things that are in more processed brands of chocolate. Too much fat is definitely not good, especially the saturated fat found in chocolate. Gerbils are more lactose intolerant than most humans so dairy isn’t a good idea for them, although dark chocolate can contain no dairy at all. Milk or white chocolate is very high in refined sugar, and that isn't healthy at all. Dark chocolate contains much less sugar, which is why it tastes more bitter. Rat owners even sometimes feed dark chocolate for respiratory issues. It's high in antioxidants and flavanols which are good for the heart. So chocolate is probably not deserving of its terrible reputation in gerbil circles, but as with the citrus fruits, just because it can be fed, doesn’t necessarily mean it should be fed.
When chia seeds are in contact with water, they swell up to 27 times their original weight and produce a thick gel. When eaten dry, they can stick to the throat, even causing blockages in rare cases16, and may also cause stomach discomfort. For humans, it is usually recommended to soak them before eating to avoid these issues.
Some advise against feeding chia seeds to animals because of the risk of choking, or swelling in the stomach causing digestive issues. On the other hand, they are often fed to rodents, apparently without issues.
Poppy seeds tend to not be advised for gerbils due to their rumoured opiate content. Poppy seeds don’t actually contain any opiates themselves, but during harvest they can be contaminated with other parts of the poppy plant which do contain opiates. Poppy seeds have even been reported to cause positive drug tests, although reports of health effects in humans are very rare.4 However, most humans eat very low quantities of poppy seeds (a couple of grams on a bagel or bread roll), whereas in some cases they could comprise 1-2% or even more of a gerbil seed mix.
Poppy seeds are sometimes included in rodent foods (especially German-style mixes e.g Rodipet) but it could not be guaranteed that residual opiates remaining on poppy seeds won’t have any effect on gerbils.
Claims that poppy seeds are toxic to rats appear to be based on a study where rats were fed a diet of 100% Mexican poppy (argemone mexicana) seeds died within 10 days.5 Mexican poppy seeds are different to the poppy seeds sold for human or pet bird consumption, and the plant and seeds are known to be harmful to other animals as well.6
If you do choose to feed poppy seeds, they shouldn’t be fed in large quantities.
Avocado contains a toxin called persin. It is present in the stone and skin, and also in the leaves and bark of the avocado tree. Persin is present in low concentrations in the flesh of the fruit, although as it leaches from the stone, nearby flesh will have higher concentrations.
In various animals, persin has been found to cause mastitis, decreased milk production and damage to the mammary glands, heart problems and gastrointestinal issues.17
There are safer choices of fruit for your gerbils than avocado, but if you do decide to feed it, feed only the flesh without the skin, and avoid the flesh directly next to the stone. Don’t feed underripe avocado. It’s probably also a good idea to not risk feeding it to pregnant or nursing animals due to persin’s effects on lactation.
The capsaicin in hot peppers can irritate the mouth and throat, and even cause abdominal pain and diarrhoea. If gerbils get chilli oil on their paws they will transfer it to their eyes, and if you’ve ever done that you’ll know how painful it is! Sweet/bell peppers are safe to feed.
Tomato plants and unripe tomatoes
Tomato stems and leaves, and to a lesser extent the unripe fruits, contain a glycoalkaloid toxin called tomatine. While tomatine is a relatively weak toxin18, and accidental consumption of small quantities of tomato plants or unripe tomatoes is very unlikely to cause death, it is safer to stick to ripe tomatoes.
Raw, green or bitter potatoes
Raw potatoes have traditionally been considered unsafe due to containing a glycoalkaloid toxin called solanine, which can cause serious illness even in fairly small quantities, and even death. However cooking actually has little effect on alkaloid levels.19 Potatoes usually only contain unsafe levels of solanine if improperly stored. Nevertheless, raw potatoes taste bad, and can cause digestive issues, so there’s no reason to feed them.
Also avoid feeding green potatoes and potatoes that taste bitter. A bitter taste is a sign of high glycoalkaloid levels. Potatoes turn green after exposure to sunlight, which also increases toxic glycoalkaloid levels.
Alliums - onion, garlic, leeks, chives etc.
Alliums are generally considered unsafe for small animals. This is probably because they are unsafe for dogs and cats. In dogs and cats alliums can damage red blood cells, causing dangerous anaemia, as well as gastrointestinal problems.20
While toxicity in one species is not a reliable indicator of toxicity in another (as with the grapes issue), there doesn't appear to be anecdotal data of alliums being fed to gerbils safely, so it is safest to avoid them.
Rhubarb leaves contain very high levels of oxalic acid21, which causes kidney stones, and in large quantities, death. Never feed rhubarb leaves to gerbils (or yourself). Rhubarb stalks are safe for humans to eat, and therefore may be fine for gerbils, but I haven’t ever heard of anyone feeding them.
Sprouted sorghum and millet
Sprouted millet and sorghum contain cyanide. The exact concentration depends on the variety, with sorghum being the most dangerous. 100g of dry sorghum seed sprouted for 3 days could contain enough cyanide to kill an adult human22, so I would recommend not feeding sprouted sorghum to your gerbils. Sprouted millet tends to contain much less cyanide23 and is likely to be less dangerous, but to be absolutely safe, it may be best avoided along with sprouted sorghum.
Gerbils are lactose-intolerant, which means they have low levels of the enzyme needed to break down lactose. When lactose isn’t broken down, it remains in the gut fermenting and could cause pain, bloating and diarrhoea. Therefore it isn’t a good idea to feed gerbils dairy products that contain a lot of lactose, such as milk, cream, soft cheeses, most yoghurts. Hard cheeses have very low lactose levels, and Greek yoghurt is sometimes fed to small animals because it is lower in lactose.
Raw beans and pulses
Some raw beans contain high levels of lectins and other compounds which affect nutrient absorption, making them unsafe to feed.
The following information is derived from A survey of the nutritional and haemagglutination properties of legume seeds generally available in the UK, published in the British Journal of Nutrition.26
Unsafe to feed raw are:
- Kidney beans
- Tepary beans
- Butter or lima beans
- Winged beans
- Mature runner beans. Note that the vegetable known as runner bean is the young pods containing immature seeds. These are safe to feed raw or cooked, but not the purplish seeds/mature beans.
Likely safe to feed raw in moderation are:
- Blackeyed peas
- Pigeon peas
- Mung beans
- Broad beans
- Adzuki beans
- Soya beans
- Pinto beans
Although the beans listed above are considered essentially non-toxic, they have been observed to depress growth when fed in very large quantities (as 50% of the diet of young rats). While you will clearly not be feeding them in this quantity it is probably worth feeding them in moderate quantities. All raw beans and pulses contain some level of anti-nutrient compounds.
Another important point is that it is apparently fairly common for bags of beans sold commercially to contain a few misidentified beans. This means an individual bean fed to your gerbil could be more toxic that the label on the bag would suggest. Only feed beans that you are sure are correctly identified.
Many garden or wild plants are poisonous to you and/or your gerbils. Assume that any plant is dangerous until you can find definite evidence to the contrary. Also, never feed unidentified plants. Some of the most common poisonous plants are:
This list is very much not exhaustive!
1. Parsley, Webmd
2. Selenium, National Institutes of Health
3. What causes grape toxicity in dogs? Playdough might have led to a breakthrough, American Animal Hospital Association
4. Update of the Scientific Opinion on opium alkaloids in poppy seeds, European Food Safety Authority
5. The toxicity of Mexican poppy (Argemone mexicana L) seeds to rats, Veterinary and human toxicology
6. Mexican poppy: What you should know, Department of Primary Industries and Regional Development
7. What Are the PH Levels of Some Common Fruits?, Reference.com
8. Lettuce, iceberg (includes crisphead types), raw, USDA FoodData Central
9. Lettuce, cos or romaine, raw, USDA FoodData Central
10. Spinach, raw, USDA FoodData Central
11. Cucumber, with peel, raw, USDA FoodData Central
12. Kale, raw, USDA FoodData Central
13. Cabbage, chinese (pak-choi), raw, USDA FoodData Central
14. Arugula, raw, USDA FoodData Central
15. Theobromine poisoning, Wikipedia
16. Watch It Grow: Esophageal Impaction With Chia Seeds, Official journal of the American College of Gastroenterology
17. Persin, Wikipedia
18. Tomatine, Wikipedia
19. Solanine, Wikipedia
20. Onions Are Toxic To Dogs, Pet Poison Helpline
21. Rhubarb Uses, Benefits & Dosage, Drugs.com Herbal Database
22. Cyanide Content of Sorghum Sprouts, Journal of Food Science
23. Cyanide content of two Nigerian local sprouted millet cultivars, International Journal of Food Sciences and Nutrition
24. Forestomach and Kidney Carcinogenicity of Caffeic Acid in F344 Rats and C57BL/6N × C3H/HeN F1 Mice, Cancer Research Journal
25. Optimization of extraction technology for determination of caffeic and chlorogenic acid in dandelion, Banat’s Journal of Biotechnology
26. A survey of the nutritional and haemagglutination properties of legume seeds generally available in the UK, British Journal of Nutrition
Wow, this is great! You've actually covered, like, everything
Umm you helped me make a food mix but do you think the poppy and chia seeds in it are ok? It contains (per 100g) 1g of poppy seeds and 8g of chia seeds 😟