Using a pole syringe to medicate venomous snakes
With a lot of practice and caution, you can learn to safely use a pole syringe to deliver a rapid, low volume intramuscular injection to a venomous snake with minimal stress to the patient. The snake must be firmly restrained at the moment of injection with a broad pinning tool or with Gentle Giant tongs.
This inexpensive, "push operated" pole syringe sold by the Campbell Pet Company (1-800-228-6364) is suitable for medicating medium to large venomous snakes from a safe distance. Another tool with a remote syringe depressor called the Safety Stick can be found here, or in the J. A. Webster catalog (1-800-225-7911) as item number 28005. It may also be possible to improvise a suitable tool. Skill and caution is required in its operation, but the tool itself is a very simple and straightforward mechanical device that extends the plunger length of a syringe to the end of a pole. Most of the commercial pole syringes commonly used to medicate large, well muscled mammals are not safe for use on snakes because they deliver the injection too forcefully using a "quick trigger" type mechanism instead of a slow and gentle manual depression.
The advantage of using a pole syringe to deliver medication is that the snake does not need to be captured or picked up. Only brief restraint is necessary to give the injection, making this a faster and less stressful procedure for snakes that violently resist being tubed. However, using a pole syringe on a live patient is a highly advanced skill requiring solid veterinary knowledge of your patient's special anatomy as well as some physical dexterity. Making errors with this advanced tool can mean seriously injuring an animal. If you have the option, it is better to leave its use to animal care professionals. Many venomous snake keepers including zookeepers and venom lab professionals do not have this option however.
Before you inject any live patient using this method, practice on a lot of bananas. Start with firm unripe bananas and progress until you can quickly and successfully inject half a cc of water into a ripe banana every time without squishing it. When you can do this, you are ready to use this technique on a live patient. Remember that half a cc is probably the highest absolute volume you want to be pushing quickly even with your larger patients. Larger volumes are possible to administer slowly via a pole syringe, but your restraint needs to last longer and to be more secure.
Snake lungs are quite close to the surface in the cranial half of the body, especially on the right hand side. If you set the length of your needle incorrectly or aim improperly you could end up delivering medication into a lung or somewhere else where it may do more harm than good. Know the anatomy of your patient before you begin. If you cannot find a good reference to crotalid or elapid anatomy in your library, dissect a dead specimen and compare it to charts that are easily available of colubrid anatomy. This picture is fairly accurate in my experience for both colubrids and elapids, but terrestrial viperids have their hearts much lower, almost midbody in some cases, and their lung can also extend farther caudally than is illustrated here. Most snakes have a well developed right lung and a smaller, vestigial left lung, with the exception of boas and pythons (family Boidae) which have two functioning lungs. Use the proper needle length for your patient (which will often have to be further shortened with a sterile rubber stopper) and aim for thick muscle. Emaciated snakes or small snakes under 300 grams are not good candidates for injecting with a pole syringe as they may not have sufficient muscle mass to reliably inject with this tool.
If you are using a "push operated" type syringe that relies on physical resistance from the animal's skin to push the syringe, a sterile rubber lab tube stopper must be threaded on the needle both to control the depth of penetration and to give a broad base of resistance for the syringe to push against. The needle hub itself may not provide sufficient resistance against reptile skin to deliver the injection, and may cause injury. We use the red rubber stoppers from Vacutainer brand 5ml serum collection tubes, 13mm by 75mm, but any sterile lab tube rubber stopper of the right size will do.
Starting from the sterile (inside) end, the needle is pushed through the exact center until the rubber stopper is directly against the hub. Only a small amount of needle should be showing through the rubber, just enough to deliver an intramuscular injection in the animal you are working with. Adjust the length of your needle and the size of your rubber stopper by experimentation to suit each patient, and discard your initial "practice setups" that are no longer sterile.
As you push the needle into the snake's body and press the syringe down, the rubber stopper will provide a safe base of resistance against the animal's skin and prevent the needle from going any deeper than it should. Be sure the gauge of needle is appropriate for the size of your patient - smaller snakes will require a tuberculin syringe and possibly a differently sized rubber stopper. If necessary you can cut a stopper down to size, but this may compromise its sterility. Adding a rubber stopper is not absolutely necessary if you have a remote plunger pole syringe such as the Safety Stick and a large patient. Smaller patients will still benefit from the rubber stopper to cut the needle length to a more appropriate size.
Intramuscular injections should generally be given in the front third of the animal due to possible renal portal issues. The thick muscles along either side of a snake's spine are good candidates for injection. Restrain the animal briefly but firmly using a broad, well padded pinning tool or well padded wide tongs such as the Gentle Giants. Because you must pin the animal firmly and decisively for a few seconds, it is very important to use a tool that can do this job without injuring the animal. A narrow pinning tool or narrow tongs can easily cause injury during this procedure. If you are using tongs, do not actually restrain the head or neck of the animal; your target is some distance below that, about 15% to 20% further down the length of the animal. On a medium sized cobra that would be from eight inches to a foot behind the head. I prefer the short (24") Gentle Giant tong for better control, but a standard sized tool can also be used.
As a rule it is better to avoid head and neck restraint especially in vipers as they can easily injure themselves by struggling. If you have reason to believe that the animal's immediate response will be to turn and bite the tong, use additional restraint on the head and neck with this broad and well padded pinning tool. Tong biting is actually not a common reaction in most venomous snake species unless your grip is tight enough to be truly uncomfortable. Padding tong jaws with high friction shelf liner type material increases your gripping power without your having to squeeze harder. With most snakes, a single skilled handler equipped with padded Gentle Giant tongs can briefly immobilize the animal at the upper third of its body, deliver the injection and release the snake before it has time to seriously struggle or to injure itself by biting a tool or a cage fixture. But not all patients can be treated this way. Some may respond with immediate and extreme defensive violence.
To immobilize a patient with a history of tong biting or extremely violent struggles under restraint, ask one handler to immobilize the snake's head and neck using a broad pinning tool while a second hander immobilizes a portion of its upper body with Gentle Giant tongs and quickly delivers the injection. Additional hands or pinning tools may be required to hold the caudal end of a large, struggling animal to avoid injury to the snake. Ideally the moment of restraint and drug delivery should be so brief that the animal has no time to struggle or attempt to bite. The purpose of using a pole syringe is to avoid having to restrain the patient in ways that are stressful or possibly injurious to the snake. If you have an extremely resistive patient you may wish to consider other methods such as hooking or luring the animal into an isoflurane box so that you can give veterinary treatment without stressing or injuring the animal.
Once the animal is safely restrained, push the needle down firmly into the thick muscles on the left side of its spine. Deliver the injection directly behind the restraint device where the snake's body is most firmly immobilized. Make sure the needle enters at right angles to the skin, or at a slight angle that will make sure that the injection is delivered into the snake's muscles and not its body cavity or internal organs. The snake cannot be allowed to struggle during the brief moment it will take to push the drug into its body or damage to the tissues may result from the needle. If you are using a "push operated" type syringe such as the Campbell model, push until you feel resistance, then immediately withdraw the syringe straight back and release the snake. Check the syringe to be sure you have delivered all of the drug. With the Safety Stick, deliver the drug using the remote plunger once the needle is properly placed.
Pole syringes are good for delivering non irritant medications which can be pushed quickly into the muscle at a high concentration and low volume. They are not the best choice for higher volume medications, injections other than intramuscular or for the injection of drugs that have a painful or physical irritant effect such as Baytril (enrofloxacin). One of the best applications of a pole syringe is to deliver a rapid dose of a pre-anesthetic sedative medication to make examination and surgical induction easier and less stressful for the patient. Regularly scheduled doses of Buprenex for pain management is another good candidate for rapid, minimal stress delivery via pole syringe to the aggressive and stress-prone patient. Click here to learn more about when sedation is really appropriate to manage venomous snakes.
There are risks as well as benefits to using sedative drugs to manage your animals, and they should be considered carefully in each individual case. Lessening risk to the handler is only one of many considerations, and in my opinion it should not be the most important factor. There are certainly many cases in which the use of anesthetic agents for invasive procedures is absolutely necessary and humane, and in those cases pre-medication with an injectable agent can make induction much more comfortable and safer for the patient.
Safe capture and restraint techniques are very important in the veterinary treatment of venomous reptilest. Refer to the main handling tutorial page for instruction on how to use the safety tools that will help minimize risks to you as well as the patient.
Anesthesia, Chemical Restraint and Pain Management
in Venomous Snakes