An American Hero:
Journey into the Rabbit Orthopedic and Spine Model for our Veterans?
By: Sandra Meyer RVT, RLATG
Peer Review By: Deborah Mook DVM, DACLAM, Emory University Department of Animal Resources
On that fateful Tuesday, January 25, 2000, the world outside the VA Medical Center in Georgia was cloaked in a pristine white, a testament to the snowstorm's recent fury. The surgeons, crucial players in rabbit surgery, were delayed by the remnants of winter's icy grip. The pressure was mounting, but destiny had plans for this day – a day that would go down in history as a baptism by snow and fur.
For me, it was a baptism of a different kind. A newcomer to the world of Laboratory Animal Research, I had left behind the cozy confines of the private practice animal hospital. My expertise prior was in the realm of companion animal surgery, particularly orthopedics. But here, in this unfamiliar terrain, I had been entrusted with the daunting task of becoming the Lead Animal Surgery Technician for the VA in Atlanta.
As the clock ticked relentlessly towards 7 a.m., I faced an unexpected adversary: the impenetrable winter coat of a New Zealand White rabbit. What I had assumed would be a straightforward task turned into a battle of determination and precision. The rabbit's fur seemed to defy gravity, swirling and twirling in every conceivable direction, challenging my every move.
With each pass of my clippers, I grappled with the fear of causing harm, the dread of clipper burn looming like a dark cloud. Clipper burn, an unforgivable mistake for someone of my experience, threatened to expose my newness in this world of research. The clippers pushed to their limits and heated up with a vengeance despite my diligent use of Cool Lube and frequent blade changes.
The Investigator, the driving force behind this surgical endeavor, arrived punctually at 7 a.m., seemingly untouched by the snowstorm's chaos. His unwavering dedication to the project was evident as he led the charge into the operating room. But this unexpected delay was a gift from the universe, granting me the precious minutes I needed to conquer the unruly rabbit fur and execute each step with meticulous care.
As the first rabbit finally graced the surgery table, I couldn't help but reflect on the incredible journey that had brought me to this point. The pressure was relentless, the challenges daunting, but I was determined to prove myself in this new career chapter. Little did I know that this day would be the crucible that forged my path as a Surgery Veterinary Technician in animal research, setting the stage for countless challenges and victories yet to come.
This guide will provide invaluable insights into ensuring the well-being of rabbits undergoing surgery or other potentially painful or distressing procedures. This guide is based on preparing 12 – 18 rabbits for spine surgery each Tuesday for over 20 years.? ??
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Rabbit Transport/Arrival Protocol:
Ground transportation – ground transportation from the vendor is much less stressful to the rabbit model -versus air-transportation.? Inotiv can provide ground transportation for delivery of rabbits -see the link and details to the rabbit ground transportation provided by Inotiv at the end of this guide.
Upon arrival -observe a one-hour resting period inside the transport crate within the dedicated rabbit housing room before transferring the rabbit to the housing cage. This essential step allows the rabbit to recuperate from any stress associated with transport. Providing this acclimation period, minimizes the likelihood of a rabbit kicking or struggling -causing injury when they are removed from the transport crate.
Hay and enrichment toys –?hay is NOT “enrichment” but is a crucial part of the daily diet in addition to pelleted feed. Provide hay and enrichment toys in the housing cage upon arrival. Provide hay daily and rotate out enrichment toys with a different toy or device at least weekly to prevent boredom and unwanted behavior.??
Considerations for Gut Motility in the Rabbit:
This consideration becomes especially crucial following surgical procedures and anesthesia, as rabbits are hindgut fermenters and are susceptible to gut stasis under these circumstances. It is essential to implement a comprehensive approach to maintain optimal gut motility.
1)????? Metoclopramide: one key strategy to address post-operative gut motility in rabbits is the administration of Metoclopramide -administered immediately after surgery to stimulate gut motility. Even in the absence of surgery, rabbit physiology is such that anesthesia can significantly reduce gut motility. Thus, the timely and appropriate use of Metoclopramide can be useful in preventing or mitigating gut stasis.
2)????? Dietary: dietary choices in pre- and post-anesthesia or surgery play a pivotal role in maintaining optimal gut motility and health. In particular, it is imperative to incorporate high-quality fiber into the rabbit's diet, daily hay -in addition to pelleted feed. Contrarily considered solely an "enrichment item," in the past, hay should be an integral part of daily food consumption. This inclusion is essential for promoting gut motility.?
3)????? Fluid management: fluid management is another critical aspect of maintaining rabbit health after surgical procedures. Lactated Ringers Solution (LRS) can be administered intravenously during the surgical procedure or subcutaneously immediately after surgery. The recommended volume for subcutaneous administration is typically around 200mls (40mls/kg) for a 5kg NZW, replenishing fluids and supporting the rabbit's recovery from anesthesia. In anticipation of potential emergencies, placing an intravenous indwelling catheter before surgery provides a means of ensuring rapid access for emergency drugs/fluids, regardless of whether IV fluid administration occurs during surgery.
?4)????? Fasting:?fasting a rabbit before surgery/anesthesia is not advisable. Rabbits cannot vomit. However, they can accumulate food and fluid within the oral cavity and oropharynx. Thus, a one-hour fast is sufficient to ensure a clear passage.?However, a one hour fast was not a part of our protocol at the VA before rabbit surgery and without consequence.??
Patient Selection and Handling on Surgery Day:
Rabbit selection- only select rabbits that eat well and have average fecal volume in the catch pan. Leave the catch pan in place several days before surgery. It is not advisable to perform surgery on a rabbit that is not eating well and does not have average fecal volume in the pan -allow several more days to reevaluate food intake and provide hay daily. In this guide, rabbits were allowed 7 – 14 days of acclimation following delivery from the vendor. Rabbits that do not produce average fecal volume in the pan following arrival are postponed to the next surgery week.
Rabbit handling and induction anesthesia- removal from the housing cage. Place the wheeled transport cart containing the animal transport container close to the housing cage (rectangular rat cages work well as rabbit transport containers). Use a small towel to cover the head/eyes of the rabbit, then scruff the rabbit over the shoulders and lift the rabbit from the housing cage while using the other hand to support the hind quarters and place the rabbit into the container.?Immediately administer the?Induction Cocktail?SC and ensure the towel continues covering the rabbit's head in the container -ensuring eyes cannot see out of the transport container. Transport the rabbit to the pre-op prep room. Radio-in to the prep room to advise “We have INCOMING!” -to ensure the noisy vacuum is not on/running.
Shaving a rabbit is a delicate task that requires careful preparation, the right equipment, and a gentle approach to ensure the safety and comfort of the animal. Follow this step-by-step guide for a successful and safe rabbit shave.? Ensure you have lubricated the eyes to prevent drying and corneal lesions as soon as the rabbit becomes anesthetized.
Before You Begin:
1.?????Gather Equipment: Collect all the necessary tools and materials, including high-quality Oster clippers with a #40 blade, clipper wash, cotton-tipped applicators, clipper oil, Cool Lube spray, a high-powered vacuum cleaner, and a tiny stiff brush.
2.?????Prepare the Environment: Ensure you have a quiet and calm workspace. All rabbits in the prep room should be under anesthesia when the vacuum is running and during shaving to minimize stress.
Shaving Process:
a) Clipper Blade Preparation:
3.?????Install a New Blade: Place a new #40 blade on the clippers.
4.?????Clean the Blade: Plug in the clippers and turn them on. Submerge the blade in clipper wash just enough to fully cover it while the clippers run at full speed for about 1 minute. Listen for the change in pitch as the manufacturing coating is removed; the low humming pitch becomes higher as the blade speeds up.
b) Blade Maintenance:
5.?????Dry the Blade: Remove the blade from the clippers and thoroughly wipe it dry using a paper towel and dry the clipper blade housing using a cotton-tipped applicator.
6.?????Apply Clipper Oil: With a tiny drop of clipper oil, lubricate the bar on the back of the blade. Wipe off excess oil and place the blade onto the clippers while they are running.? Allow the clippers to run for 10-15 seconds to distribute the oil across the bar. Turn off the clippers, remove the blade, and wipe off any excess oil.
7.????Apply Cool Lube: Spray a light mist of Cool Lube on the teeth of the blade to help dissolve any remaining oil or clipper wash. Ensure no oil touches the cutting edge/teeth of the blade.
c) Clipping Technique:
8.????Proper Placement: Return the blade to the clippers, ensuring the clippers are running while the blade is locked into place to ensure proper placement in the housing.
9.????Fur Removal: Use a high-powered vacuum cleaner to remove loose fur from the blade during shaving. Vacuum the blade often, spray it with Cool Lube, and let the clippers rest once they become warm but before becoming hot. Ensure all Cool Lube is dry before use. Use two pairs of clippers to rotate out the entire clipper and rest them, as cool blades quickly heat up on hot clippers.
10.?? Blade Teeth: Before clipping, ensure the blade is free of wash and the Cool Lube is dry. Hair can become stuck in the teeth if any residue or a small skin particle is present. If the blade nicks the skin, immediately switch to a dry blade and perform the above cleaning process.
11.?? Blade Teeth Cleaning: Use the tiny stiff brush that comes with the clippers to clean the teeth of the blade and remove small skin particles.
d) Proper Clipping Angle:
12.?? Hold Clippers Properly: Always hold the clippers with the teeth side up during clipping. Avoid using the "raking method" with the clippers upside down, as it can cause skin grabbing and injuries.
13.?? Taut Skin: Keep the skin taut in the area you’re shaving -at all times- by placing your hand above or below the area you're shaving. Without grasping the skin, apply enough pressure to slide/pull taut the skin away from the area you're shaving.
14.?? Clip Against Hair Growth: Clip against the direction of hair growth to achieve a close shave. Be mindful of the angle at which you hold the clippers.
15.?? Practice and Muscle Control:?Achieving the proper technique may take practice and can build strength in the operator's arm holding the clippers. Be gentle, and do not over-apply pressure with the clippers during the process.
16.?? Damage Control: Keep the clipper cord positioned to avoid pulling them off the table. Always have backup clippers on hand in case of emergencies.
17.?? Rabbit Respirations: rabbits are obligate nasal breathers. As such, ensure the nares are not obstructed for any reason once anesthetized and during the shaving process.
18.?? Nail Trimming: Trim the rabbits nails using large dog nail clippers.
Additional Tips:
Using hair remover cream on a rabbit can irritate the skin unless it's for a small area that can be rinsed away thoroughly with water, as rabbits are sensitive to hair remover creams.
·??????? Vacuum loose hair often to maintain good visibility of the skin prep area.
·??????? Administer all analgesics prior to shaving the rabbit -to provide adequate onset time.? Administer any epidural following skin preparation using aseptic technique.
·??????? Shave the chest between the forelimbs (just under the dewlap to the xiphoid process) for post-operative application of a transdermal Fentanyl patch.? This location provides superficial vasculature for better topical absorption, reduced fur density, reduced rapid fur regrowth, and less likely to be chewed off.? Special note: rabbits with an existing transdermal fentanyl patch in place on the skin, then placed on a heating pad, can cause rapid fentanyl absorption.? Avoid having the fentanyl patch make contact with any heating pad following placement.
Skin Prep:
Chlorhexidine scrub and chlorhexidine solution are preferred over betadine for sensitive rabbit skin. Once the rabbit is shaved, use a stainless steel container to soak 4X4 gauze in 70% alcohol and an additional stainless steel container of 4X4 gauze to pour chlorhexidine scrub/soap over the gauze and add just enough sterile irrigated water to the container to saturate the gauze. Perform three target fashion scrubs with chlorhexidine scrub in a circular fashion and follow with alcohol after each scrub. Be sure to remove all chlorhexidine scrub with alcohol after the last/final scrub -any chlorhexidine scrub left behind can irritate and cause dry skin and pruritus. Final skin prep -spray the prepped area with a 10% chlorhexidine solution and allow it to dry before the incision into the skin.
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Anesthetic and Analgesic Agents:
Rabbit anesthetic induction cocktail - in this guide, a combination of Ketamine, Xylazine, and Acepromazine is prepared and administered subcutaneously (SC) as an induction agent prior to isoflurane/inhalant gas anesthesia.? Special note: Intramuscular administration (IM) of an induction agent is unnecessary and can potentially increase pre-operative stress in the rabbit.? Inhalant gas anesthesia should not be used as an induction method in an unanesthetized rabbit.
Analgesics -epidural morphine, meloxicam, buprenorphine and a fentanyl transdermal patch are among the most common analgesics used in multi-modal pain management in the rabbit model.
Preservative-free?morphine combined with sterile saline- may be administered as a single injection in the epidural space at the L7-S1 (lumbosacral region) in the rabbit for intra-operative and post-operative pain management (multi-modal) in procedures extending from the xiphoid process to the hind limbs. The single injection of preservative- free morphine provides analgesia for approximately 12 -18 hours -allowing time for the fentanyl transdermal patch to become systemic.
Rabbit Endotracheal Intubation:?
Rabbit endotracheal intubation necessity?-is dependent on the procedure performed. The rule in veterinary medicine is to "do no harm." Endotracheal intubation may not be essential for most operations when the breathing rate and depth during anesthesia are appropriately monitored and adjusted accordingly. Rabbits are not intubated in any studies conducted in developing this guide -and without incident. Instead, the 12-18 rabbits per day were masked with maintenance isoflurane gas once placed on the surgery table using a cat-sized nose cone and held in place by placing the nose cone into a cat-breathing muzzle with Velcro straps wrapped behind the rabbit's ears. If you prefer to place an endotracheal tube, please get in touch with me via LinkedIn – I have written a publication in Vol. 23 No. 5, May 2002 issue of Veterinary Technician Journal under the “step by step 291” in placing an endotracheal tube in a rabbit using the?blind?technique.?
UPDATE: as of 2023,?v-gel Advanced Rabbit?is available in the USA through Jorgensen Laboratories and is a simple and excellent alternative to placing an endotracheal tube in a rabbit -image below. Currently, the VA in Atlanta is using v-gel Advanced Rabbit in orthopedic rabbit surgeries and has replaced masking with a nose cone.?See the reference link at the end of this guide.
Physical monitoring parameters -to gauge anesthetic depth by physical methods, the corneal reflex is effective in the rabbit -as a rear-limb toe pinch doesn’t always produce a reflex following morphine epidural anesthesia. Respiration rates should be 30-60/min, heart rate 120-325/min and body temperature maintained around 100-101 degrees F.? Mucous membrane color should be pink -not blue or grey- and best determined by the tongue and the inside of the ear coloration.?
Thermal support:?use a water-circulating heating pad on the surgery table (turn the machine on 30 minutes before use). Water-circulating heating units are best to avoid thermal burns. Rabbits are highly susceptible to hypothermia -slowing recovery and inducing further stress on the rabbit. Ensure the water level is at the?operational level?in the water circulation system after turning on the machine and allowing time for the heating pad to become filled. Use only distilled water or water for?wound irrigation?to fill the machine used for the water-circulating heating pad. Minerals in tap water can deteriorate the operations of the water-circulating machine.
Wound closure?– turn the inhalant gas anesthesia down to a recovery setting (0.5%-1%) or OFF on the vaporizer once wound closure begins. Use skin suture material with at least four throws that are NOT over-tightened! Tighten slightly on 2nd throw and tighten down on 3rd throw (allow skin room to swell slightly, and sutures will not become buried in the skin during healing). Cut the suture ends close to the skin/ no long tails!
Oxygen only and immediate post-op thermal support?-allow the rabbit to breathe only oxygen (without inhalant gas) for at least five or more minutes before removing the rabbit from the surgery table. Place the rabbit onto another water-circulating pad and cover the rabbit(s) with a hospital-quality blanket for recovery from anesthesia. Preferred and best is placing the rabbit(s)?on?a warm air-circulating pad (Bair Hugger Animal Blanket)! Cover the animal(s) with a?lightweight?bed sheet -exposing only the animal's head. The Bair Hugger (see reference at the end of this article) is the preferred method of warming a rabbit following anesthesia or surgery and warms the rabbit quickly -speeding up anesthesia recovery time. The lightweight bed sheet will?balloon out, producing a -warm air bubble- environment inside the sheet. Monitor mucous membrane colorations and prevent eye-drying from circulating warm air -by lubricating the eyes again if necessary.?
Administer SC Lactated Ringers (LRS) and apply the Fentanyl patch- Use chlorhexidine 10% solution to prep the skin between the forelimbs for the fentanyl patch placement and allow the skin to dry before placing the fentanyl transdermal patch. Administer?warm?SC LRS when IV fluids are not provided during the surgical procedure. Place the LRS bag into a tray of warm water between rabbits for 15 minutes -leaving the IV line port of entry at the bag unsubmerged/unexposed to the water. Or better yet, use a fluid bag warmer.?
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Post Operative Care and monitoring:
Rabbit cage catch pan – rabbits should be singly housed following surgery to prevent unwanted cage mate grooming and the ability to monitor individual rabbits.?Place a clean catch pan under the rabbit floor grate on the day of surgery to monitor fecal production and urination following surgery. Monitor fecal and urine volume in the pan daily and check the rabbit's skin turgor over the shoulders (for hydration status). Provide additional enrichment treats whenever reduced fecal production is observed (rabbits love apples). Administer SC LRS accordingly and as needed following skin turgor assessment.
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Hay and Enrichment?– be sure to provide hay each day. Provide "Prang Oral-Rehydrator Certified" (Bio-Serv) in an?anti-spill?bowl immediately following surgery, treats, and other enrichment food items each day for the first three days -minimum- following surgery.
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Toys?– be sure toys and enrichment items are replaced weekly (or more frequently) with different toys or devices to prevent unwanted boredom behavior and promote increased activity.?Bio-Serv?has many enrichment toys and gadgets! Bio-Serv, particularly Karen Froberg-Fejko DVM, has a?long-standing?history in our industry in presenting EXCELLENT behavioral and professional advice regarding rabbit well-being and presented during AALAS and AALAS branch conferences.
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Fentanyl patch?– ensure the fentanyl patch stays in place for 72 hours, starting at day one post-op. Without removing the rabbit from the cage, use your hand to reach under the chest to check the patch.
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Wound monitoring?– ensure the wound stays fully intact without dehiscence and the rabbit isn't trying to chew or self-mutilate. There are many factors to consider in preventing self-mutilation, such as lateral lower chest, abdominal, or limb incisions within easy reach of the rabbit's mouth are a target for chewing, especially if the suture was pulled too tight during closure or skin staples were used to close the wound.
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Bite-Not Collar or E-Collar?– make a Bite-Not collar for a rabbit that tries to chew their surgery site. The Bite-Not collar is made using three rolls of 2-inch Vet Wrap material and applied to the rabbit under anesthesia. Vet Wrap will contract once applied, and it is essential to place/insert a hand between the neck and the Vet Wrap while wrapping the Vet Wrap around the neck and over the hand. Maintain the 2-inch width of the Vet Wrap during application. The operator should not stretch the Vet Wrap during application and instead place it in its' slightly unstretched form around the neck and hand. The hand placement prevents the Vet Wrap from being placed too tightly around the neck.?
The resulting bite-not collar appears like a giant donut around the neck and is held from slipping off the head by the rabbit's ear. The collar should fit slightly loose but tight enough to prevent slipping past the ears.
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The bulky collar prevents the rabbit from bending the neck to the side to prevent chewing a lateral or dorsal incision/surgery site on the body and hind limbs -when applied with the proper tightness around the neck to prevent bending the neck fully to each side. If the rabbit can reach the surgery site, the collar is too loose; if the rabbit's eyes bulge following application, the collar is too tight and should be removed and reapplied under anesthesia. The Bite-Not collar is a less stressful alternative to an Elizabethan Collar (E-Collar).?
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Stiff E-Collars prevent the rabbits' peripheral vision and can be stressful to a rabbit. An E-Collar made of a flexible material works well, can be bent backward over the shoulders (neck skirt), and prevent the rabbit from chewing or self-mutilating the surgery site. Apply the flexible E-Collar with care by placing 2-3 fingers between the rabbit's neck and the E-Collar string while tying the E-Collar onto the neck. Tie the E-Collar string using a double knot, then cut off the long ends (no bow). Bow tying doesn't work with a rabbit, as the rabbit will easily untie a bow. The rabbit may chew the flexible E-Collar, which must be replaced as needed. It is not necessary to anesthetize a rabbit to apply an E-Collar.
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Social housing?– social housing is of great importance in the rabbit. Consider the age of the female rabbit in accomplishing successful social housing. Female rabbits beyond 8-10 months old when first introduced can be more challenging to socially house -but not impossible. Social housing can help to avoid stereotypical behaviors associated with single housing. Once all surgical wounds have healed, rabbits should be socially housed in compatible pairs or more whenever possible. Monitor rabbits closely during social introduction for the first 2-4 hours. Rough play is typical. However, vocalizations during rough play after eight or more hours together may indicate an incompatibility.??
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Conclusion:
Rabbit surgery and preparation is a complex and delicate process that requires precise preparation, multi-modal analgesia, vigilant anesthesia monitoring, careful wound closure, and proper pre and post-operative care.?
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Special dedication: to Paul McKellips in honor of the many decades of service to our country and recognition of his contributions to the biomedical research community in raising awareness through communications and publications throughout his US military career.?
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?Special thanks: to Lisa Lefebvre ALAT -for 20 years of assisting in preparing 12-18 rabbits for surgery each Tuesday morning. I could not have done this alone without Lisa’s dedication in assisting. I cannot think of a single time that Lisa could not help me prepare the rabbits for surgery each week!
References:
About the author:
?Following Sandy’s employment as the Animal Resources Manager and Facility Supervisor at the Atlanta VA Medical Center for 21 years, Sandy has been employed with Inotiv since October 2021 as a Customer Service Associate and Coordinator of Internal Departmental Communications. Sandy served on the VA IACUC during her entire tenure and the Emory University IACUC as liaison for the VA IACUC. During her supervisory work at the Atlanta VA, Sandy was responsible for ensuring the health of all the animals. Providing active support in animal anesthesia and surgical support in USDA-covered species and rodents - with almost ten years of prior specialty experience in orthopedic pain management in a private practice/animal hospital. Sandy served in the Surgical Proficiency Assurance and Post Approval Monitoring (PAM) assessment for the VA IACUC and was a voting member assigned to the proposed animal project review. Sandy was responsible for developing and updating all animal facility SOPs, contributing to developing IACUC policies, and developing the tri-annual AAALAC Program Description. Sandy co-founded the Georgia Veterinary Technician and Assistant Association and is a published author in Veterinary Technician Journal. Sandy has been a member of AALAS and SEAALAS since 2000 and has served SEAALAS as a Director -for two terms- as the Communication Committee Chair -for three terms- and on the Planning Committee -for three terms. Sandy was awarded the National Veterinary Technician Nursing Award by the Veterinary Technician Journal in 1999, the SEAALAS Technician of the Year Award in 2009, and the Charles River Laboratories Linda Hazel Memorial Award in 2015.??