When selecting the appropriate cannula length for remote delivery, several factors must be considered:
Species of Animal: What species are you delivering the Remote Delivery Device (RDD) to?
Purpose of Administration: Are you sedating or medicating?
Type of Injectable Liquid: What type of injectable liquid is intended to be delivered?
Reason for Delivery: Why are you administering the injectable liquid?
Injection Method: Will the injection be subcutaneous (SQ) or intramuscular (IM)?
Animal Characteristics: What is the species, size, and gender of the animal?
Timing: What time of year are you delivering the injectable liquid?
The original focus of this article, released in 2017, was on Whitetail deer, but the concepts can be applied to other species as well. While the specific requirements will depend on the species you are working with and guidance from your veterinarian, the following general advice applies:
For subcutaneous injections in most mammals, such as deer and cattle, a ½ inch cannula equipped with a gelatin collar is usually adequate. When administering subcutaneous injections, the shot placement should be within the O-Zone™ area (the neck region forward of the front shoulder). Most injectables used to treat illnesses are specifically labeled for SQ injection. Always follow your veterinarian’s instructions and the label directions for proper administration choice (SQ vs IM).
For capture work, whether in the field or a controlled environment, additional considerations are necessary. Most sedation medications are labeled for intramuscular injection, and it is crucial to use the proper cannula length to ensure IM delivery for the species you are capturing, taking the animal’s body score and the time of year into account.
For male Whitetail deer (WTD) six months and older, a ¾ inch end-port discharge cannula is generally sufficient for intramuscular injectables. However, in the fall and winter, factors such as hair density, body condition, and hormonal changes during breeding season may necessitate a longer cannula and increased drug volume. Understanding and adapting to these changes is key to successful sedation.
For example, an adult male WTD immobilized in September may require a specific drug volume supported by a ¾ inch cannula. This same animal in the fall will likely have increased its body mass by 20-30% due to hormonal changes from breeding season activity. Consequently, a larger amount of immobilizing agent and a longer cannula may be needed for ideal sedation.
If not delivered intramuscularly, lipophilic drugs can accumulate in fatty tissue, causing delayed or secondary sedation. Therefore, it is discouraged to use a ¾ inch tri-port cannula for IM injectables during and after the breeding season for adult WTD. By using an extended cannula length and end-port discharge, successful procedures can be achieved with lipophilic drugs such as butorphanol (a component in the widely used sedation injectable “BAM”).
The same principles apply to cattle and other animals. It is crucial to consult with your veterinarian to choose the appropriate cannula length based on the medication type, the time of year, the animal’s fat and hormonal conditions, and its body condition.
By taking the time to ensure a solid VCPR (Veterinarian-Client-Patient Relationship) and considering all potential changes in your animal, the process of remote delivery will become more consistent, saving time, and reducing stress for everyone involved.
Note: All decisions regarding animal health should be consulted with your veterinarian before execution.