Tube feeding a snake — cheap and easy

How to administer oral medications or pureed food to a snake.

Article contributed by a Snake Getters volunteer

This is written from a North American perspective. In other parts of the world, the available equipment, nomenclature or units of measure may be different—I don't know. It also tries to err on the side of overexplaining. Apologies if you find it long-winded.

A NOTE FOR BENIGHTED AMERICANS:

One milliliter (ml) is the same thing as one cubic centimeter (cc). Milliliter is the more correct term, but cc is commonly used in speech. One ml of water weights one gram, a fact that is useful when computing metabolic water requirements, given as a percentage of body weight. 1% of 1 kg is 10 g, or 10 ml. If you insist on using antiquated units, it is true that one British imperial fluid ounce of water weighs almost exactly one ounce. The U.S., of course, uses a different fluid ounce 4.3% larger, but it's still close enough for rough approximations.

TOOLS

In addition to whatever it is you want to get into your snake's stomach, you need:

  • A tube to go down the snake's throat,
  • A syringe to measure and hold the stuff to go down the snake's throat, and
  • Some lubricant to make the above go smoothly.

THE TUBE

You can get rigid stainless-steel ball-tipped feeding needles, which last forever and are very handy. But they cost more ($14 or so), and the extra control comes with the extra risk of injuring the snake's throat if you're not careful. The cheaper and softer alternatives are the common red rubber human urinary catheters. These cost a little under a dollar in serious bulk, and a little over in small quantities. (I pay US$1.25 for most sizes). They're generally 16 inches long, and have a smooth curved tip, with openings on either side near the tip. The other end is flared like a funnel, so you can cut off the end to fit various size syringes. Any vet will have these, but the prices can vary widely as they're not something they commonly sell so there may be an "inconvenient oddball sale" mark-up. I have found that most cities have at least one good pharmacy, usually old and not as shiny as the chains, that stocks the oddball stuff. They'll have nebulizer cups, ostomy supplies, and what we're looking for: incontinence supplies.

The catheters come in a considerable range of sizes, usually even-numbered "French". If you care, each french is 1/3 of a mm, so a 12fr catheter is 4mm in diameter. 8 to 18 is the common range. You may also find Foley catheters, which you don't want. They have an inflatable balloon at the end to keep them from pulling out. The small sizes are so flexible they're hard to feed down, so get something reasonable. On the other hand, thick ones have a large internal volume, which is inconvenient for giving small doses of medication. Get the smaller ones (10-14 Fr) for medication and the larger ones (18 Fr and up) for bulk feeding.

THE SYRINGE

The second thing you'll need is a syringe. 6 or 10 ml may be appropriate for drug dosing, while 20 to 60 ml is better for feeding, depending on the size of the snake. For small amounts of medication (less than 1 ml) in a reasonable-sized snake, you can usually do away with the tube and use a 1 ml needleless syringe (often called a tuberculin syringe), and just stick the whole syringe down the throat of the snake. This is generally far enough to get the liquid down the stomach, if the snake is large enough to take the diameter of the syringe, and small enough that the length of the syringe is a meaningful distance down its throat. This short-cut may also be inadvisable with aggressive snakes that are likely to bite your hand.

Giving extra water, as recommended in the drugs section, can also preclude using a syringe this small.

If possible, when feeding, get a catheter-tip syringe. These have large-bore tips that fit the untrimmed catheters and pass lumpy pastes better. However, a regular Luer tip (the small size that fits hypodermic needles) will be fine for drugs and can be managed with thin foodstuffs. Remember that wider (larger-bore) syringes require more force to press, which can become quite significant if your food is at all thick and you just have a little Luer tip on the syringe.

Thus, use the smallest syringe that you can. Intermediate in size is an oral dosing syringe tip, which has a wider tip than the regular Luer tip, so that a needle won't fit on it. Many pharmacies have these. They're also known as "O-ring syringes". While the standard bore isn't any larger than a Luer tip, they can be easily drilled out to a more comfortable diameter. For a Luer or oral dosing tip, you'll have to cut the flared catheter end to fit.

If you're giving food (or other thick paste), take particular care to make it as tight as you can. Having it slip off halfway through just as you're pressing hard on the syringe is remarkably messy. When giving drugs, the non-trivial volume of the catheter itself matters. You want to include an air bubble in the syringe large enough to flush all the liquid through the catheter, so you don't leave half of the drug dose in the catheter. Try drawing up some water from a cup to see how much air space is needed. (And add half a ml more, just to be sure.) Usually it's easiest to pull up the air and drug into the syringe without the catheter, put the catheter on, advance the liquid most of the way down the catheter, and then you're ready to insert.

THE LUBE

This is for the snake's comfort. If you've ever experienced a urinary catheter first-hand, you shouldn't need the importance explained to you. If necessary, you can just get the catheter wet, but some suitable water-based lubricant such as K-Y jelly would be better. These days, you can get "personal lubricants" in an amazing variety of colors and flavors, but snake-friendly ones (mouse pee scent?) are rare, so best to stick with the basics. Just enough on the tip to make the process smooth.

THE MENU

The next step is tp prepare whatever you're giving. There are two basic categories of things you might want to tube-feed a snake: drugs and food.

DRUGS

With any drug, additional water is generally a good idea. Many drugs are removed from the bloodstream by the kidneys, so they tend to accumulate there. Giving extra water helps flush the kidneys and prevent toxic effects. While not always necessary, it basically never does any harm, and is a good practice if you don't know one way or ther other.

1% of its body weight (10 ml per kg) is a good rule of thumb. This is a substantial fraction of a snake's daily water requirements (usually 1–2% of body weight) without being so much you risk regurgitation if given all at once. (If it doesn't seem like much, 1% of a 75 kg/165 lb human's body weight is 750 ml. How fast can you drink a full wine bottle without upsetting your stomach?)

In fact, if you're doing a large number of animals with the same drug, it's useful to make up a small cup of pre-diluted mixture which you give at 10 ml per kg. While a dehydrated snake needs balanced electrolytes (Pedialyte is a reasonable approximation) to maximize absorption, tap water is fine for a normally hydrated animal.

For example, fenbendazole (Panacur) is a common drug for internal parasites. It generally comes in a 100 mg/ml liquid solution, and is administered at 50 mg/kg. If you want to give 10 ml/kg, then you need 50 mg/10 ml = 5 mg/ml, so you dilute it 20 times: 1 part Panacur with 19 parts tap water. (Pancur settles, so shake well before drawing from the main bottle, and "suck and blow" a few times when you're drawing up the diluted mixture to stir it up.) Note that doing reduces the concentrations of preservatives that are in some drugs to the point that they will no longer keep, so don't try to keep the diluted mixtures around for any length of time unless you know it's safe for the drug in question.

FOOD

Snakes can eat a lot, but remember that a debilitated snake can have trouble coping with a huge meal. Better to start with something small if the snake's skinny and weak. A very debilitated animal may not be able to properly digest food. Food placed in its stomach may actually rot and cause bacterial problems. Start with small amounts of food and watch for bowel movements.

For foods, I have used the following:

  • Mazuri amphibian and carnivorous reptile gel, made up with tepid water so it doesn't gel. This is supposed to be a nutritionally complete diet designed for carnivorous reptiles and amphibians. It mixes up rather gritty, and has lumps that won't fit through a luer tip reliably. A drilled-out oral feeding tip or catheter tip works fine, however.

  • Hill's A/D prescription diet. This is a high fat and protein pet food that is pureed like baby food for tube-feeding. The term "prescription" means that it's for special purposes and generally sold through veterinarians rather than pet stores, but no prescription is required to get it. Many small animal veterinarians stock it and will sell it over the counter. Just call around looking for some and pick it up from wherever you find a reasonable price. I think I pay US$1.25 for a 156g (5.5 oz) can. The UPC number is 0-52742-56700-6, if that helps anybody.

    Hill's A/D is not properly balanced for long-term use, or to make up for a pre-existing nutritional deficiency. Even in a healthy patient, it can cause gout. Think of it like eating nothing but McDonald's for an equivalent time. Fine if your main complaint is hunger and you don't do it for months at a time. Not so good if you're diabetic or already suffering from a vitamin C deficiency. For long term maintenance, it is better to use a diet specifically formulated to meet the nutritional needs of carnivorous reptiles.

    Proteins are chains of amino acids. When protein is digested, it is disassembled into amino acids, absorbed into the bloodstream, and used to build new proteins in the body. Any imbalance between what is eaten and what is needed requires getting rid of the excess. There are about 24 standard amino acids, so there's usually an excess of something. 8 of the most common fall into 2 families based on a core ring structure: purines and pyrimidines. Excess purines are metabolized by the liver into uric acid, which is excreted by the kidneys. Excess uric acid (more than the kidneys can excrete) can crystalize elsewhere, causing gout. Excess pyrimidines are metabolized more fully into simpler amino acids, carbon dioxide, and ammonia. These are easier for the kidneys to get rid of. Hillspet A/D is high in purine, and consequently should not be used in debilitated patients whose kidneys may already be stressed or in conjunction with nephrotoxic drugs such as Amikacin.
  • Gerber's lamb, or other all-meat, baby food. Not properly balanced for a carnivore, or as a complete diet, but it's something, and can be found at a number of 24-hour stores if time is of the essence.

  • One more thing that I haven't tried, but should: Walkabout Farm's Enteral Carnivore diet. The owner of the company, Susan Donaghue, is a very well respected nutritionist with a particular interest in reptiles. You'll find her name at the front of the Nutrition chapter in Mader. Given both her reptuation and other veterinary recommendations I have heard, I'm inclined to believe the high price is justified.

Any of these can (and should) be thinned with water or Pedialyte to an easily tubable consistency. You can either suck up the food (slow, but straightforward), or pull out the plunger and spoon it into the syringe (faster, but messy). In the latter case, to minimize air bubbles, don't try to pour each spoonful down to the tip end, instead let each spoonful push the previous lot a bit further down, with all the air together in one big bubble that is slowly squeezed out the tip.

A third way I've just started trying is to spoon the paste into a small zip-lock bag, squeeze out most of the air, cut the little bit off one corner, and use it like a pastry bag to squirt into the syringe. This seems to work best if I hold the syringe vertical and squirt the stream down the middle of the syringe to the tip end. Once you have the syringe filled, advance the food to the end of the tube, lubricate it, and it's time to insert it down the snake

GIVING IT TO THE PATIENT

This is actually quite easy. Just wiggle the end of the tube between the snake's jaws. The backward-pointing teeth present no particular challenge to get past. The only thing tricky is making absolutely sure that you don't stick the tube down the snake's windpipe. One way to make sure is to open the snake's mouth with something (tongue depressor, pencil, or whatever) and look once you've got a bit down the mouth to make sure you've bypassed the glottis (opening of the windpipe). This is is at the front of a snake's mouth, where the tip of your tongue is in your mouth when it's closed! Putting anything into the lungs is extremely bad. Putting a large quantity of thick paste down there (snakes can't cough like mammals) is deadly. A snake's glottis is usually closed, so it's hard to get the tube in there by accident, but Murphy's law says that you'll get lucky about the fifth time you try tube-feeding, just when you're starting to think that you know what you're doing.

The other way, which I usually find easier, is just to start at the back corner of the snake's mouth rather than trying to use the tongue opening at the front. There are usually fewer teeth to fight there, and because you're starting behind the glottis, you can't possibly hit it.

Once it's in, advance the tube about 1/4 to 1/3 of the way down the snake and start squeezing. Don't push the syringe so far down that you can't keep a grip on the feeding tube itself. I've had snakes suddenly try to eat the tube, and if it's already entirely in their mouth, they can pull it off the syringe.

If you have to give more than will fit in one syringe, you can pull the syringe off and substitute another, as long as you don't mind the mess and keep careful watch to make sure the snake doesn't swallow the feeding tube in the meantime. Usually, the feeding tube pulls straight out, but do it slowly; it might catch on the snake's teeth. If this happens, twist the tube side to side until the teeth lose their purchase before continuing.

You have now successfully tube-fed a snake.

Click here for another article on assist feeding venomous snakes.
Emaciation (Starvation) Protocol article from Melissa Kaplan's Herp Care collection
Fluids and Fluid Therapy in Reptiles from Melissa Kaplan's Herp Care collection


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