DIY Enrichment

Novel Ferret Enrichment: Ferrets Have A Ball

By Nicole Madera, Donnie Adams, Shonn Offord, and Amy Funk

Ferrets (Mustela putorius furo) are recognized as the gold standard animal model for studying respiratory diseases. While the hallmark signs of these types of diseases are similar between ferrets and humans, their natural behavior is not. The behavioral characteristics of ferrets can be very distinct from other species as well and challenging to recreate in a research facility. The best types of enrichment for lab animals are ones that encourage the expression of positive species-specific behavior. A recent paper showed that ferrets in enriched cages produce more exploratory behavior similar to polecats in the wild, with 17.5% of their time spent with exploratory behavior.2 When compared to unenriched cages, time budgets are spent mostly with inactivity, with eating, drinking, and exploratory behavior accounting for only 0.4% of their total time budget in a day.2 Ferrets were domesticated for their hunting prowess to control vermin and ability to tunnel narrow holes to ferret out prey. They demonstrate similar unique behaviors to their weasel counterparts. While most of them are undesirable, such as hissing, screaming, biting, and attacking, there is one, the Weasel War Dance, also known as the Dance of Joy, that, when seen, is positively correlated to a ferret that is thoroughly enjoying themselves. Members of the weasel subfamily hunt in packs, and this behavior is thought to be seen when they are celebrating triumph and victory after a hunt. To satisfy their natural behavior as tunnel dwellers, we sought to build a custom complex enrichment device (Figure 1) that would provide them with opportunities to display their natural behavior and enjoyment of tubes and tunnels (Figures 2 and 3). Ferrets have binocular vision with horizontally slit pupils common in species that chase prey with gaits characterized by a hopping motion. This biology could explain their fascination with balls,3 and we thought this would aid in increasing exploratory behavior. Ball pits are a common enrichment for young humans, and it was shown to increase a positive emotional state in rats.1

Material and Methods

Animals

All ferrets that experienced time in this novel enrichment device were on a St. Jude Children’s Research Hospital IACUC-approved study where enrichment would not interfere with study parameters. No ferrets experienced pain or distress. Ferrets on campus are socially housed in 3 tier racks (Allentown, Allentown, New Jersey) with 6 banks on a 12:12h light-dark cycle with ad libitum food (Purina Lab Diet SL14 High Density Ferret Diet, St. Louis, MO) and water in an AAALACi- accredited facility.

Figure 1: Diagram of the ball bits with parts labeled. Figure 2: Close-up images of connecting pipes.

Figure 3: Ferrets within the tunnels that go back and forth between the two stock tanks.

Equipment

The ball pit was built using two 120-gallon stock tanks (Plastic-Mart, Hoppers, IA) joined together by clear 4” schedule 40 PVC pipes (Ferguson Plumbing Supply, Memphis, TN). Each of the stock tanks (Figure 3) had, two of the following: 4” PVC male adapters, 4” PVC ninety-degree elbows, and 4” forty-five-degree elbows (Spears PVC Pipe Supplies, Olive Branch MS) securing them together as one unit. A 4” electrical conduit nut (Industrial Sales Co., Bartlett, TN) was welded with two ¼” nuts to screw in two ¼” bolts for easy installation and removal when sanitizing the ball pit. To attach the tunnels to the main stock tanks (Figure 4), a total of ten each was used: 24x1 eyebolts, 24 nylon lock nuts, and 3/16x1 fender washers. A small chain and clasp were used to add support for the middle of the tunnel.

Stainless steel Kong toys on a 5 1/2” quick link chain was (Bio-Serv,3 Foster Lane, NJ) suspended over each stock tank with a PVC pipe. The bar going across the top was made with a ¾” schedule 80 PVC with ten each of the following: 24x1 1/2” eyebolts, 24 nylon lock nuts, and 3/16”x1” fender washers. This bar was secured to the stock tanks by drilling two holes with a diameter of 4 ½” and connecting them with male adapters and electrical nuts. The stock tanks were filled with non-crushable plastic balls (Little Tikes Balls for Kids® , Memphis, TN) to add environmental complexity. Sanitation of this equipment was accomplished by soaking the balls in a 10% bleach solution for a minimum 30-minute contact time. This hand-sanitation process was validated with PocketSwab® Plus ATP swabs (Charm Sciences, Lawrence, MA). The rest of the equipment was disassembled and sent through cage wash

Figure 4. A tunneling ferret exploring the ball pit for the first time.

Figure 5. Sniffing behavior by a ferret in a novel environment.

Figure 6. Ferrets exhibiting body postures not normally seen in their home cages.

Figure 7. Ferret exploratory behavior.

Conclusion

Four male adult ferrets were tested to see if they preferred the stock tank with the balls or one without balls and more positive behaviors were seen in the ball pit, such as sniffing (Figure 5), exploratory behavior (Figure 6) prey capture, and the Weasel War Dance (Figure 7) as compared to a stock tank without balls. This innovative ball pit was constructed with low-cost plumbing supplies and served to elicit positive behaviors not seen in the home cage of ferrets. More work is needed to better understand what other types of enrichment would encourage more of these affiliative behaviors.

Special thanks to Biomedical Engineer, Bradley Lindley in Facility Operations, who developed the design with us to ensure safety for our animals. Much appreciation to Biomedical Communications photographer, Ann M. Hedges for the excellent photos of ferrets in action. Thank you, Felecia Moore, Animal Services Supervisor, for improving our diagram of the ball pit. We are grateful to you for your skills and endless energy. Nicole Madera is a Veterinary Technologist II in the Animal Resources Center at St. Jude Children’s Research Hospital in Memphis, Tennessee. Donnie Adams is an Animal Health Technician I in the Animal Resources Center at St. Jude Children’s Research Hospital in Memphis, Tennessee. Shonn Offord is a Husbandry Floor Supervisor in the Animal Resources Center at St. Jude Children’s Research Hospital in Memphis, Tennessee. Amy Funk, DVM, DACLAM is a Staff Veterinarian in the Animal Resources Center at St. Jude Children’s Research Hospital in Memphis, Tennessee.

REFERENCES 1. Hinchcliffe, JK, MG Jackson, and ES Robinson. 2022. The use of ball pits and playpens in laboratory Lister Hooded male rats induces ultrasonic vocalisations indicating a more positive affective state and can reduce the welfare impacts of aversive procedures. Lab Anim, 2022: p. 236772211065920. 2. Larrat, S and N Summa. 2021. Ferret Behavior Medicine. Vet Clin North Am Exot Anim Pract, 2021. 24(1): p. 37-51. 3. Talbot, S, R Freire, and S Wassens. 2021. Effect of captivity and management on behaviour of the domestic ferret (Mustela putorius furo). Applied Animal Behaviour Science, 2014. 151: p. 94-101.