The innovative ferret restrainer has become a necessity in the field of experimental research due to the growing interest in ferrets as laboratory animals. The ferret, domesticated for more than a thousand years, was traditionally used for tracking animals that lived in burrows. Today, the ferret is an essential laboratory animal used in biomedical studies as a model for countless imperative human clinical syndromes and diseases, for instance, the Reye syndrome, Helicobacter gastritis, and antiemetic drug screening.
For experiments that entail repetitive venipuncture or extended intravenous infusion, or sampling methods, the ferret can serve effectively as a substitute non-rodent animal model. The ferret restrainer serves as a reliable tool designed to facilitate the handling of ferrets in the research laboratory.
Restraint devices developed for long-term and short-term animal studies should meet the standard protocols for comfort and stress while also meeting the functional requirements of the researcher in terms of productivity and control of the animal. For the ferret specifically, a restraint device needs to be reliable enough to endure repetitive cleanings, and its design must protect the animal and the handler from any injuries that may transpire with repeated use. The device must also guarantee restraint and prevent escape.
Apparatus and Equipment
Owing to the marked sexual dimorphism of the ferrets, the diverse ages of the animals used in research investigations as well as the species’ seasonal bodily transformations, developing a single-sized restraint device was deemed impractical. As a result, four different sizes of restraint devices emerged.
Typically, the components of the ferret restrainer can be divided into eight parts which include a Delrin washer, a Lexan nose cone slide, a clamping stainless steel screw, a Plexiglas/Lexan nose cone, a Lexan rear gate, a Lexan rear support leg, a Lexan front support leg, and a Lexan/Plexiglas restraint tube (McLain, 2006).
The inside diameters of the restraining tubes corresponding to the different body weight ranges are 6.4 cm for a 400 – 700 g animal, 7.9 cm for a 650 – 1,100 g animal, 8.8 cm for a 1,000 – 1,750 g animal, and 10.1 cm for a 1,500 – 2,300 g animal.
Ferrets possess an evident need for physical and social contact making them agreeable to restraint technology in general, and the ferret restrainer device in particular. Primarily, the ferret restrainer aims to facilitate the use of ferrets in the research laboratory and provide the researcher with efficiency and control of the animal to obtain reliable research data. Introduction to the restraint device may possibly call for the animal to have some preliminary time to explore the equipment. An extra restraint tube positioned inside the cage with socializing animals will significantly decrease, if not completely remove, the primary initiation time and defiance by the animal.
To make certain that the ferret restrainer performs its task proficiently, it is essential to place it on an even surface so that the front and back legs of the device are steady. Then slide the nose cone approaching the front of the tube making sure to keep the distance at least the length of the animal’s body (excluding the tail), and gently tighten the clamping screw. Next, place the animal at the back of the restrainer, take out the rear gate and let the animal go into it while lightly holding and raising the tail in an upward direction. Reattach the rear gate and at the same time position the tail through the top central mark, then let go of the tail. Next, place the cone on the nose of the ferret while adjusting the position of the nose cone to reach the level of animal immobility necessary for the process by moving it a little forward or backward.
Ferrets are inclined towards a colder room temperature than most lab animals and quickly give in to heat stress. Consequently, the restraint tube and nose cone ought to have openings for sufficient ventilation and passage of air. Whenever needed, a little tabletop fan can additionally improve the passage of air. The transparent Lexan/Plexiglas tube material allows a clear vision of the animal to permit stress monitoring. An appropriately restrained ferret will not demonstrate body jerking or other noticeable escape effortsfall asleep. Ferrets restrained for longer periods ought to be regularly monitored for any indications of stress.
Biomedical research models that use surrogate nonrodent animals, such as the ferret, can make use of the ferret restrainer to perform repetitive venipuncture or prolonged intravenous infusion procedures. Whereas the elementary ferret restraining equipment initially introduced by Curl and Curl was restricted to limited or initial intravenous dosing or blood sampling, the novel ferret restrainer has gained value as an apparatus for various biomedical experiments on human clinical syndromes and diseases.
Additionally, the intravenous access abilities of the laboratory have enhanced, and progressively more lengthy and recurrent infusions or samplings are needed in animals of various sizes. Thus, a sophisticated restraint method has become even more valuable. The ferret restrainer device serves the dual purpose of accommodating the growing expertise of the laboratory’s technical staff and at the same time providing a safe and convenient animal restraint.
The ferret restrainer facilitates the process of blood sampling without the use of tranquilizers or anesthetics. The most common blood collection sites in ferrets include the lateral saphenous vein, the cephalic vein, the jugular vein, dorsal metatarsal vein, and the cranial vena cava. Less frequent sites endorsed incsetlude the caudal artery of the tail, and the orbital sinus (Smith et al., 2015).
Treatment execution can entail a subcutaneously tunneled jugular catheter that goes out from the head of the tube or use of the caudal vein. For prolonged intravenous infusions (over a period of 2 hours), it would be more convenient to take into account a jacket and swivel tethering technique to permit more freedom of movement. Contrary to earlier belief, it is possible to access the caudal veins and arteries of the ferret with some practice. Skilled technicians become quickly proficient in this method, and, through the utilization of the restraint device, execute this process without further assistance.
Strengths and Limitations
The major advantage of the modern ferret restrainer is that it allows the researcher to focus solely on the venipuncture process or blood sampling techniques. While the manual restraint technique involves several complicated methods for blood sampling, most of them require specialized personnel or more than one technician. In general, anesthesia is not required for most blood collection processes. However, the infamously thick skin of the ferrets makes access to veins difficult. Thus, some researchers are prompted to anesthetize the animal before manual restraint and manipulation. The drawback of this method is that the use of anesthetics likes isoflurane may negatively affect the outcomes of blood parameters in ferrets, and this needs to be taken into account when interpreting the results. The total red blood cell, white blood cell, and platelet numbers can be considerably lower in anesthetized ferrets.
Another advantage of the ferret restrainer is that it exploits the innate nature of the ferrets which makes them so amenable to the restraint technology. In reality, ferrets have an obvious need for physical and social connection and are also naturally drawn to enclosed spaces. Both of these factors result in their eagerness to enter the restraint tube without any signs of enthusiasm or anxiety.
More importantly, ferrets do not normally appear to link the device with any particularly undesirable procedure, which allows countless procedures or manipulations every day on the same animal. Scientific evidence regarding maximum procedure period or chronicity, thrice-weekly treatments with a test agent by extended intravenous infusion for as long as 90 days (15 – 30 minutes/day) has not resulted in any noticeable aversion towards the apparatus or procedures used.
- The ferret restraining device is typically comprised of a washer, a nose cone slide, clamping screws, a nose cone, a rear gate, a rear support leg, a front support leg and a restraint tube.
- The ferret restrainer allows the investigator to focus exclusively on the blood sampling technique without the inconvenience of manual restraint.
- The restraint technique can provide assistance in procedures such as repetitive venipuncture or prolonged intravenous infusion procedures performed on nonrodent animals.
- The benefits of the restraint device have extended to studies involving biomedical experiments on human clinical syndrome and diseases.
McLain DE. (2006). Use of an adjustable restraint device for prolonged and intermittent intravenous infusion and blood sampling in ferrets. Lab Anim (NY).;35(7):47-50.
Smith SA, Zimmerman K, Moore DM. (2015). Hematology of the domestic ferret (Mustela putorius furo). Vet Clin North Am Exot Anim Pract ;18(1):1-8. doi: 10.1016/j.cvex.2014.09.005
Curl JL, Curl JS. (1985). Restraint device for serial blood sampling of ferrets. Lab Anim Sci ;35(3):296-7.