Menadione Synthetic Vitamin K

Menadione sodium bisulfite complex (synthetic vitamin K) is a common supplement in pet food. With the trend moving towards more natural, holistic and organic pet foods, this additive has become a controversial ingredient because of a misunderstanding of its purpose and its toxic effects in certain laboratory settings.

Menadione Safety Concerns?

It’s true that menadione has some cytotoxic effects, depending on its purity and dose. It is also being studied for its anti-cancer and anti-inflammatory benefits. Some concern comes from the fact that the product has a Material Safety Data Sheet that outlines some concerns and cautionary procedures when working with the substance. However, many common products have MSDS labeling. One reason there is a MSDS for menadione is because it’s typically handled in a setting where it is mixed to form other products; since there are some concerns, it gets reported on the sheet. The same is true for many ingredients of common products, like Vitamin C. It sounds scary when named ascorbic acid and has its own MSDS: “MUTAGENIC EFFECTS: Mutagenic for mammalian somatic cells. Mutagenic for
bacteria and/or yeast.” Whoa!

Check out calcium carbonate’s MSDS: “The substance may be toxic to kidneys. Repeated or prolonged exposure to the substance can produce target organs damage.” However, this really boils down to handle any purified substance with care; don’t inhale any powders; and too much of anything is bad for you.

In case the Group 3 Carcinagenic in the MSDS for menadione scares you, it’s simply the group for substances unclassifiable to carcinogenicity in humans. The following list the categories of possible carcinogens according to International Agency for Research on Cancer:

Group 1: Carcinogenic to humans
Group 2A: Probably carcinogenic to humans
Group 2B: Possibly carcinogenic to humans
Group 3: Unclassifiable as to carcinogenicity in humans
Group 4: Probably not carcinogenic to humans

To be clear, this is not proof that it is not carcinogenic, just that it has not been proven in humans. The data on causing cancer in animal cells is also a little muddied. It is understandable to be careful with it. However, it appears that eating grilled meat and potato chips is more likely to be cancer-causing.

Menadione in Pet Food

As for the use of MSBC in animal feed, it’s been around for a long, long time and there are no verified, well-cited studies that I can find that indicate it has ever caused harm when used in small doses as a food additive. I have emphasized the last part because injections of large-doses of synthetic Vitamin K can lead to issues; again, too much of anything is harmful. “The dose makes the Poison” – Paracelsus.

There are numerous claims from well-meaning, but misguided, bloggers, animal caretakers and those that fall for the “Appeal to Nature” fallacy. The way we arbitrarily classify products as “natural” or “artificial” is inherently flawed and we cannot let something as important as health be swayed by personal philosophy.

This is where an understanding of the scientific comes in very handy. Just wanting something to be true does not make it true. The more people you convince that something is true does not make it true. Anecdotal evidence can only be trusted so far. Actual research and experimentation should be the basis of any health, nutrition or science claim.

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Polydactyl Crested Geckos

Polydactyly (or polydactylism) is a scientific term for having extra digits (fingers or toes) beyond the number than is considered normal for the majority of the population. Extra toes are not always present in the same number on both feet or among individuals; this irregularity has caused some concern about the genetic fitness of this trait and its impact within a population. Polydactyly has been found in mammals (including humans), birds and reptiles. Few examples are found in the wild, but they do occur[1].


Some people view any structural difference as a “flaw” and therefor undesirable. Show standards are influenced by what people expect to see in an animal. Enthusiasts don’t want to reproduce such a disqualifying flaw in their breeding stock. We aren’t there yet with crested geckos or any other reptiles. However, most of us strive to breed for the nicest-looking geckos and to some, and an extra toe is just plain weird.

There is a lot of misunderstanding around these extra toes. Some see anything like this as a suspicious product of inbreeding. Through a bit of research, we believe that the forms of polydactyly seen in crested geckos are really just a random mutation that, while heritable, is not a reflection of inbreeding. Keepers are breeding thousands of these geckos a year, and mutations are bound to appear more often. That doesn’t necessarily mean that the rate of occurrence is changing. However, because there is a strong genetic link that is heritable, we do understand the caution many breeders feel regarding this trait.

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Reptile Pets as Gifts

Pets do not make good presents.

Pets especially do not make good holiday gifts. Pets really especially don’t make good holiday gifts for kids! Even adults should not be surprised with a new pet, even if they have shown interest in one. Being immediately saddled with responsibility over a living being can turn a usually wonderful, rewarding experience into a burden. Kids are not well equipped at the best of times to take care of a pet on their own. The holidays are a hectic time of year to add another family member! Folks may be leaving town, have guests in the house or otherwise be too busy to care for a new pet. Kids will get distracted by other holiday gifts and may neglect their new arrival – even if they begged for one in the first place! It’s better for both the people and the animal to wait until a quieter time, so that everyone can get used to the new situation.


It’s also best if a person picks out their own pet. Some personalities can clash – this goes for reptiles as well as cats and dogs! In particular, reptiles should be thoroughly researched as their needs are unique. Some are looking for particular breeds, ages, sizes, colors or patterns. Some people want a furry friend, while others are more interested in something scaly. Choosing a pet is a very individual decision. You don’t want your holiday gift to wind up in an animal shelter if things don’t work out. Pets such as fish and reptiles are at risk due to their specific needs which are often challenging for a novice to meet.

For children who are old enough (10+ years) and are ready to get started, you can make a trip to an animal shelter or reptile rescue to see what’s available before opting to buy one. Do so after the holidays are over! You might want to have the child write a short essay on how to care for the animal to show you that they are both interested and informed. Make sure you also know your stuff, as parents will be the ultimate caretaker for any pet! Always select a healthy individual if you are new to caring for the species; many reptile rescues have healthy animals that the owners could no longer care for. Another reason to avoid surprising your loved ones with a new pet!

The best gift to give an animal lover who wants a new pet are supplies or a goodie basket. For reptiles, this could mean a starter 20 gallon tank (suitable for most baby reptiles and some adults), some artificial plants, food & water bowls, lighting and heating equipment and safe cleaning supplies. Also consider gift cards or a “good for” certificate they can redeem for a pet of their choice. A responsible breeder may offer competitive holiday discounts, while suggesting that delivery of the animal happen later. Make sure these gifts are refundable, should the receiver change her mind or if living circumstances change to where pets are not possible.

Other alternative gift ideas for the holidays are artwork, jewelry or T-shirts featuring the type of pet in question. As long as you aren’t introducing a living creature, celebrate their love of animals by gifting locally made or handcrafted items. A local reptile show may have some unique and reasonably priced items. Your present can still show you care, without risking the life and well-being of another living creature.

Finding a Reptile Pet Sitter

It’s the holidays and people travel away from home for a weekend or even a few weeks. Even if you only have one reptile to care for, going on vacation can be stressful to both you and your pet. Many keepers with large collections never take the opportunity to travel due to the lack of experienced reptile pet sitters or other resources to care for the animals while they are away. Whether you are only going on a weekend getaway, a week-long trip, or a 2 week vacation this guide will help you find a pet sitter and how to prepare them to care for your reptiles properly while you are away. Extended time away from home may require a friend or fellow enthusiast who can keep them on a semi-permanent basis. Many military servicemen and women have to leave their collection for extended periods of time and should have a buddy who doesn’t mind the time and money involved in their care.

The biggest concerns while you are away are power outages, automatic mister failure, central air breakdowns or heater mishaps. Keep things simple and don’t ask too much from your pet sitter – reptiles can go a long time without food. If your sitter isn’t comfortable with live bug feedings, just have her spray and change out the food every few days.

If you keep snakes, which are very easy to care for, your friends and family may not want to feed them or they may be afraid of them. Lizards and tortoises often need to be fed and watered daily. Some frogs can go for a week between feedings but more delicate and active dart frogs should be fed every other day. Not everyone can deal with feeding out crickets and other bugs to insectivores. Herbivores seem to be easier but have complex diets and supplementation needs. So minimally you need someone to come over every other day even if its not for feeding; they should check up on your pets and visually check for health, any escapees, normal behavior and general safety of the enclosures.

It’s a good idea to leave some cash behind in case you run out of supplies, such as greens for tortoises, Uromastyx and bearded dragons,; insects for frogs, geckos and other bug-eating lizards; supplements and light bulbs which can burn out without warning while you are out of town. The longer you are gone for, the more money you should leave behind. If you will be unreachable, you should leave enough to cover a vet visit just in case.

Choosing a Sitter

Even someone who doesn’t really like reptiles but can follow a detailed set of instructions can make a good sitter for a week or less. If you find a responsible person, it works out really well.

Walk your sitter through the process one week before and then again the night before leaving. For diurnal animals, have them come in and provide fresh food and water as necessary for the species in the early morning. Nocturnal reptiles should be cared for during the early afternoon. This allows the sitter to get into the enclosures and put out the food and water before the critters are awake. Most tanks should be cleaned out weekly, so you will need a sitter comfortable with handling reptiles in case the cages need cleaning.

List out the types of food & supplements and any equipment they will need to use. Show them how to operate the lights, heating elements and misting systems, if you have them.

A good reptile vet may often provide pet sitting services, similar to a kennel for dogs. Local pet stores familiar with reptiles can also be a good resource, and may offer kenneling for less than a vet would charge. A great resource is a local herpetological club! Members there may be more than happy to care for your pets for a small fee, and you’ll know they have some experience with reptiles.

If your collection is small, you may be able to drop your reptiles off at your sitter’s house. If you have a lot of animals, you may consider drawing a diagram of the reptile room with each enclosure labeled if they require different care. You don’t want your Uromastyx to be sprayed every night and you don’t want your crested geckos to be fed a mixed green salad!

Have a backup plan for your pet sitter. You should give them another emergency contact number preferably someone local such as a family member or good friend. Leave the name of your reptile vet and any 24 hour emergency vets who will see reptiles. As morbid as it is, you should consider updating your will and emergency contacts with a person responsible for caring for your animals if you should pass away.

Keep the following on hand in plain sight in the reptile room or centralized location:

  • Pre-made or pre-mixed food (prepped reptile “salad” or crested gecko diet)
  • Frozen pre-killed prey items for snakes and omnivores
  • A few dozen appropriately sized crickets or other insect feeders
  • Supplements (don’t pre-mix dry supplements into food)
  • Water spray bottles or refills for misting systems
  • Paper towels
  • Reptile safe cleaner
  • Hand sanitizer
  • Written instructions on how & when to feed
  • Emergency contact numbers
  • Reptile veterinarian locations nearby
  • Local pet stores
  • Extra cash ($10-$20) for emergencies

In particular, Crested Geckos are very easy to leave in the care of a reptile novice. Leave premixed food in a squirt bottle (used for ketchup & mustard at picnics) in the refrigerator, keep a spray bottle (or misting system) full of water next to the enclosures and provide clean food bowls within reach so the sitter can replace at each feeding. It’s pretty simple and should only take less than a minute per gecko every other day. As long as you provide a water bowl, cresties can be sprayed every other night if your house isn’t too dry. Typically cresties can comfortably go a week without food, but ideally should be fed 2-3 times a week. Try to work out a schedule that works for you and your sitter.

Good luck, and happy holidays!

What to Look for in a Crested Gecko Food

Crested geckos are one of the easiest reptiles to keep for novice enthusiasts because there are several frugivorous gecko foods available in pet shops and online. The list of acceptable commercial diets has grown, as interest in providing variety while maintaining the ease of a powdered meal replacement product is a hot topic. While it seems like everyone and their brother have their own crested gecko recipe in the works, it’s important to understand some basics in nutrition before deciding on a primary product or home-brewed recipe.

Whole foods are the only source of nutrition in the wild: live, whole prey and unprocessed vegetable matter. Therefore, it might seem strange to offer dry, kibbled or semi-moist foods. Wild foods offer the variety that is required in nature for animals to survive. However, in captivity we are severely limited in the choice of food items due to climate, availability, and the fear of herbicides, pesticides, toxic metals and other contaminants in the environment that affect wild caught bugs and field harvested plants. To make up for nutritional deficiencies, we must opt for other solutions. Domestic produce from the supermarket rarely provides enough protein, calcium and fiber, vitamins or trace minerals to support every life stage. You need to supplement the diet, whether that means sprinkling a powder onto a fruit blend or feeder insect, or mixing a complete packaged diet with water to make a smoothie. By understanding the ingredients in popular pet foods, including those for crested geckos, we can choose the most appropriate diet. You may find that the “unnatural” powdered foods are based on whole food nutrition.

“Although some prepared foods have been available for only a limited time, the overall nutritional quality of commercially prepared foods is rapidly improving as manufacturers consider new scientific information when they prepare their formulations.” – Stahl and Donoghue, 2010 “Nutrition of Reptiles”, Small animal clinical nutrition, fifth edition

The most important step in choosing an appropriate commercially prepared crested gecko food is to Read the Label! The order of ingredients is important, as they are usually listed by quantity, with the bulk ingredients at the front and the trace elements at the end. Many pet food manufacturers neglect this and at times you’ll see labels quietly changed to reflect the true ratios. Let’s walk through some of the necessary elements.

Macronutrients: Protein, Fat & Carbohydrates

Each reptile species has varying needs, whether carnivore, omnivore, insectivore, frugivore or herbivore. Little is known about the specific nutritional requirements for crested geckos, but they are classified as omnivores. Anecdotal reports conflict on how much of their diet is comprised of fruit, pollen, nectar or insects, but these are all possible foods to a wild crested gecko. Because of this, it’s best to opt for variety to ensure your gecko gets the proper nutrition and stimulation from their captive diet.

Susan Donoghue & Julie Langenberg, in Douglas Mader’s Reptile Medicine and Surgery (pg 151), report generalized reptile nutrition statistics as follows:

  • Carnivores should consume 25-60% protein, 30-60% fat and <10% carbohydrate
  • Omnivores should consume 15-40% protein, 5-40% fat and 20-75% carbohydrate
  • Herbivores should consume 15-35% protein, <10% fat, and 55-75% carbohydrate

Proteins are important chemical compounds of amino acids. These amino acids get broken apart from the protein chain so they can then be used for various functions within the body. Essential amino acids are required from foods, while non-essential ones can be bio-synthesized within the body (but also can be extracted from food). Insects, on a Dry Matter Basis, range from around 40-76% protein. However, each insect species varies and there is also variation among individual insects depending on life stage and diet. It is assumed that most (non-toxic, parasite-free) insects should be appropriate for omnivores that consume invertebrate prey.

It is worth noting that insects can lack essential amino acids. Notably, in chickens fed an insect-meal diet, these limiting amino acids included arginine and methionine. Good sources of arginine are dairy products, meat, wheat germ and many nuts and seeds, including pumpkin and sesame. Good sources of methionine are eggs, meat, sesame seeds, oats and other cereal grains.

Plant proteins are also variable in their essential amino acid content. Cereals are low in lysine while legumes are low on methionine. So providing a good variety of both insects, animal products and plant proteins can help ensure your pet is getting the proper “building blocks”, as protein is often dubbed.

Growth rates generally correlate to protein intake, assuming temperatures are adequate for metabolization. This is why adding insects to the diet, even when feeding a commercial product, seems to result in faster growth. As omnivores, a crested gecko’s diet should contain 15%-40% protein. Most commercial gecko foods are 20-30%.

Fats are another important element to reptile diets. Fatty acids are a nutritional requirement, assisting in the absorption of Vitamins A, D, E & K, acting as an energy storehouse, cushioning internal organs and maintaining body temperature. Good sources of fats in commercial diet should contain linoleic acid and linolenic acid (the omega oils), which are lacking in roach species used for live food. Good sources include flax, safflower, chia, hemp and soy oils. A variety of insects can provide different levels of fatty acids, so include crickets, roaches, waxworms, silkworms & soldier fly larva. As omnivores, a crested gecko’s diet should range between 5-40% fat. This is a wide range, and we don’t know exactly what crested geckos need. Too much fat can cause obesity!

Carbohydrates are another piece of the nutritional pie. For crested geckos, this is provided not only directly from the fruit and nectars they eat, but also the gut contents of feeder insects. Their main carbohydrates should be relatively high in sugars and low in fiber, the composition of most fruits. The omnivorous reptile should consume 20-75% carbohydrate.

Dietary Minerals & Vitamins

Calcium is probably the most talked about nutrient in reptile diets because it is the most often deficient in the captive diet. What isn’t as well known is the necessity of Vitamin D3 in the calcium absorption process. This vitamin, technically a hormone, is a unlike most other nutrients as it can be synthesized by the body if given adequate exposure to UVB light. UVB can come from special lighting or from unfiltered sunlight. Dietary D3 can be supplemented for insectivores, as insects do not contain much, if any, D3. As nocturnal animals, it is uncertain how efficient crested geckos are at utilizing UVB for D3 synthesis, so it has been included in most commercial brands.

Many people dump on excessive amounts of calcium powder into fruit mixes and onto feeder insects, which comes with its own set of problems. Calcium requirements for mammals and birds is set at 1% of the diet, with Phosphorus .5%, and Vitamin D3 at 200 to 1000 IU/kg. Maximum tolerances (the upper limits in the diet) are 2.5% calcium, 1.6% phosphorus and 5000 IU/kg for D3.

Interactions between vitamins (A, D & E in a ratio of 100:10:1) and calcium and phosphorus, complicate the nutritional spectrum in terms of trace minerals. “Common problems are deficiencies of zinc, copper, or iodine due to excessive calcium supplementation, and conditional vitamin E deficiencies due to polyunsaturated fatty acids.” (Mader 165)

Common Additions to Commercial Diets

Obviously, the goal of any gecko food should be to combine healthy ingredients with delicious ingredients. If your gecko won’t eat it, what’s the point of it being healthy? So you may find some interesting items on the labels of commercial diets.

  • Dried Honey: this makes it taste sweet and can act as a preservative
  • Bee Pollen: can act as an appetite stimulant and provides nutrients
  • Weird Green Stuff: AKA spirulina, kelp & algae which add iodine & trace minerals
  • Herbs & Spices: Paprika, turmeric and other spices contain carotenoids that boost coloration and play a part in maintaining good health.

If your brand of gecko diet doesn’t have any of the above, it doesn’t mean it’s not healthy. The addition of some of these ingredients may seem like a gimmick, but many do provide actual health benefits beyond just hype.

Homemade Diets vs Commercial Food

Unfortunately, the foods we think of as natural become less nutritious or otherwise unsuitable as a mainstay. Feeding only muscle meat to a carnivore may seem a simple way to care for their nutritional needs, but it doesn’t provide the wealth of minerals and vitamins found in the bones, organs and viscera of a whole animal. Many dog, cat and ferret enthusiasts have found benefits in feeding whole prey to their pets.

For frugivorous reptiles like crested geckos, we are tempted to throw some fruit in a blender and call it “gecko food”. However, such a blend may be a nice treat every once in a while, but it’s not a balanced diet. By denaturing the fruit (often missing the peel, seeds and insects often present in aged fruit which they feed on naturally), we are concentrating the sugar and calories down into something very nutritionally dense, which could cause obesity and imbalance of other nutrients over time.

You can attempt to make a crested gecko diet yourself, if you feel you are up to the challenge. You don’t have to rely on a commercial product. Many keepers have the knowledge and experience to make healthy fruit blends at home. Just be sure you pick the right fruits and your supplements are fresh, as vitamins erode after about 6 months. Provide a balanced diet to your feeder insects and be sure to dust them! Many keepers feed a supplemented fruit mix 2-3 nights a week and bugs twice a week with good results.

Gecko Food Summary

Adding fresh fruit to the diet a few times a month, along with feeding gutloaded, dusted bugs is a way of adding variety while still relying on a well-balanced commercial diet. Just make sure to read the labels and check that it’s actually providing a complete diet. Forget about brand loyalty, it’s all about what’s good for your geckos! It may take some time to settle on a primary food. But with all the choices available, you should be able to choose one that your geckos will readily eat that provides the nutrition they need.

Douglas R Mader, Reptile Medicine & Surgery.
Merck Veterinary Manual: Reptile Nutrition
Stahl, S, Donoghue, S. 2010. Nutrition of Reptiles. In Small animal clinical nutrition, fifth edition: 1237-1254.