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These brief summaries are designed to be quicker and easier to read than a full journal article, but more informative than an abstract. Basically I want to give you the background of why the study is important, their findings, if there were any major deficiencies in the study, and what you should take away from it in the end. I hope this saves you some time! 

Roeder M, Boscan P, Rao S, et al. Use of maropitant for pain management in domestic rabbits (Oryctolagus cuniculus) undergoing elective orchiectomy or ovariohysterectomy. Journal of Exotic Pet Medicine 2023;47:14–20.

Introduction: 

Maropitant is an neurokinin-1 (NK1) receptor antagonist. These receptors are found in the vomiting center of the brain, as well as many peripheral tissues,  including throughout the gastrointestinal tract. Maropitant has been found to have inhalant anesthetic MAC-sparing effects in dogs, cats and rats, but no studies have shown the benefits of using maropitant as a perioperative analgesic. There have been 2 pharmacokinetic studies looking at maropitant in rabbits, but no pharmacodynamic studies prior to this study. 

Methods: 

This prospective study across 3 institutions looked at healthy rabbits presenting for elective altering. A total of 28 female and 23 male rabbits were included; there were 17 rabbits in the 2 mg/kg maropitant group, 19 rabbits in the 10 mg/kg maropitant group, and 15 rabbits in the saline control group. 2 mg/kg is the canine label dose and a previous pharmacokinetic study in rabbits showed that a 10 mg/kg SQ dose resulted in plasma concentrations that were shown to be effective in dogs. Any rabbits that had anesthetic and/or surgical complications were excluded from the study. A variety of anesthetic protocols were used, but rabbits were always administered buprenorphine 0.06 mg/kg IM q8hrs and meloxicam 1 mg/kg IM q24hrs for analgesia. Surgeons and observers were blinded to which rabbits were in each group. 

Rabbits were monitored post-operatively using a continuously recording video camera for 24 hours or until discharge. Clips of the footage taken at regular intervals were viewed by multiple blinded observers to assess pain, behavior and activity scores. The rabbit facial grimace scale and a pain related behavioral assessment scale were used to score the rabbits. Food intake and fecal output were also measured post-operatively. 

Results/Discussion:

Food intake and fecal output decreased somewhat in the rabbits that received the higher dose of maropitant, but the authors noted a larger sample size is needed to confirm the effect of the drug and dosage on the rabbit GI tract. Interestingly, male and female rabbits showed comparable pain and behavior scores, despite the likely variation in soft tissue trauma and surgical time.

Potential factors that could have affected the outcome of this study included variation in anesthetic protocols, surgeon experience levels (varying degree of visceral pain and soft tissue trauma secondary to technique), small sample size, and the fact that many rabbits were discharged earlier than 12 hours so the authors were unable to include and assess that data, which in turn could have skewed food intake/fecal output data. 

The authors recommend against using maropitant 10 mg/kg SQ due to potential negative effects on the gastrointestinal tract. Ultimately, larger studies are needed to determine if maropitant is an effective visceral pain analgesic in rabbits. 

Takeaways:

While many of us have seen anecdotal evidence of maropitant helping with what we presume to be visceral pain (with GI stasis, liver lobe torsion, etc), Maropitant 2 mg/kg and 10 mg/kg SQ did not reduce pain in rabbits undergoing elective orchiectomy or ovariohysterectomy compared to control groups in this study. Is it possible we are seeing improvement in the aforementioned cases because the maropitant is addressing nausea rather than pain? Ultimately, we need more studies to further assess this. Given the lack of adverse effects with administration of 2 mg/kg, administration of this dosage may not help, but is unlikely to hurt. 

Hollwarth AJ, Dutton TAG. Retrospective Analysis of Pelvic Limb Fracture Management in Companion Psittacine Birds (60 Cases). Journal of Avian Medicine and Surgery 2023;37(2): 165-174. 

Introduction: 

While psittacine pelvic limb fractures are common, there is limited literature regarding fracture management, healing times and complication rates. This paper hypothesized that birds undergoing surgical fracture repair would heal more quickly and have lower complication rates. 

This is a retrospective cross sectional study evaluating pelvic limb long bone fractures in companion psittacines from 2005 to 2020. If you’ve long forgotten study classifications like I have - this means the study assessed medical records from a set time period and gathered data to evaluate the prevalence of the problem (pelvic limb fractures) and characteristics about those affected (type/location of fracture, treatment elected, time to healing, complications, etc). This type of study is unable to determine cause-and-effect relationships, but can make inferences about correlations or gather data to support further research. 

Methods:

This study included 60 cases consisting of 22 different species, aged 8 weeks to 25 years old, equally distributed between male and female (among sexed birds). 71.7% of fractures were tibiotarsal, with femoral then tarsometatarsal following, fairly evenly split. The most common fracture types were closed, simple and diaphyseal fractures. Methods used for fracture management included external coaptation, surgery and cage rest. 

A variety of fracture management methods were used, with surgical correction most commonly used for the tibiotarsus, and medical and surgical options used nearly equally for femoral fractures and tarsometatarsal fractures.

Diagram illustrating ESF-IM tie-in fixator used in a tibiotarsal fracture of a raptor, From: Bueno I, Redig PT, Rendahl AK. External skeletal fixator intramedullary pin tie-in for the repair of tibiotarsal fractures in raptors: 37 cases (1995–2011). JAVMA 2015;247:1154–1160.

The study defined satisfactory resolution of repair as a palpable firm swelling and stability of bone on palpation or visible callus on radiographs, as well as return to normal function in the affected limb. 

Complications observed included postoperative discomfort, patient interference, bandage complications such as swelling, or wounds, osteomyelitis, refracture or fracture of other long bones, delayed healing or death secondary to fracture complications or during anesthesia/surgery for fixation. 25 out of 60 cases reported 1 or more complications, and there was no significant difference in complication incidence between the fracture locations. Utilizing an aluminum foam-backed splint/soft tissue bandage had the highest complication rate at 61.5% of cases and tape splints had a complication rate of about 41%. Surgical pinning alone had a complication rate of about 35%.

Documented reasons for avoiding surgical pinning included open fractures with gross contamination, temporary splinting to determine viability of the foot, poor bone density, cost of procedure, size of the patient and a final case consisting of only a chip fracture which could not be stabilized surgically. 

Complications led to amputation of the affected limb in 3 cases. Birds that died during healing all had comorbidities including metabolic bone disease, an episode of aspiration during medication administration and psittacosis. 

Results/Discussion:

Average time to healing was 33 days. Resolution was obtained in 47/55 (86%) of patients that were followed to conclusion, however there were complications in 25/60 or nearly 42% of patients. The most common complication was patient interference with bandages and/or splints, and it occurred most commonly with external coaptation.

47 of the cases were followed during healing and healing times ranged from 11 to 121 days, with an average of 33 days. Femoral fractures healed quicker and tibiotarsal fractures required the longest time to heal on average, but they all had similar median healing time of about 31 days. Birds less than 490 grams had faster average and median time to callus versus larger patients. Birds that experienced complications had longer average and median healing times. 

Delayed union was observed in 4 cases, with osteomyelitis and attempted conservative management techniques apparent contributing factors. 

46 out of 50 patients followed long term had no reported complications. The 4 birds that developed long term complications included mild angular limb deformities, pododermatitis in the contralateral foot and digit arthrosis, all of which were either non-issues for the patient or were able to be treated medically. 

The authors note that ultimately, fracture management should be determined on a case-by-case basis. Splinting and bandaging are most commonly used in small birds <300g. Tape splinting was very commonly reported, but also had a higher complication rate than reported in a previous study, which should be taken into account when determining fixation method. 

External coaptation resulted in a much higher complication rate than surgical intervention, likely due to the behavior of psittacins. Ensuring appropriate analgesia and judicious use of an elizabethan collar can help prevent patient interference. 

Study limitations included the retrospective nature, small sample sizes and subjective assessment of healing by 10 different practitioners. Further studies comparing patients with and without comorbidities could be helpful. 

Takeaways:

There is no one correct way to repair a pelvic limb fracture in a psittacine because the best treatment will depend on the patient in front of you, the client’s finances, and your comfort level with different repairs. However, if possible, surgical repair with an external skeletal fixator - intramedullary tie-in fixator results in a quicker resolution with a lower complication rate, especially in larger psittacines. 

Do you agree with my assessment of these studies? Do you have questions that I didn't answer? Comment below or reach out to me!

I’m going to start out this clinical series by going back to the basics. Even if you’ve been seeing rabbits for years, read on for a review of performing a complete, systematic physical exam on rabbits. 

You probably heard this in vet school, but the most important factor in performing a complete physical exam, every time, in any species, is to develop a system. In my first few months as a veterinarian, I developed a system for my physical exam in cats and dogs, which is not altogether unique, taking a nose to tail approach. Since most of our exotic companion mammals are prey species, I have adapted that technique to try to minimize fear and anxiety in these patients. Rabbits also have some unique anatomic characteristics that should be kept in mind when performing a physical exam. 

Before I ever touch the patient, I perform an observational exam. If the rabbit is in an exam room, I will have the owner open the carrier before I come in the room, lay out a non-slip mat out and encourage the rabbit to move around. If I am examining the patient as a drop off or hospitalization, I will visually examine them in the kennel prior to handling.

A few things I look for:

• respiratory rate and character

• ocular and/or nasal discharge

• mobility (any limping, dragging limbs, etc)

• signs of pain such as squinted eyes, flared nostrils and pinned back ears (see this graphic of the Rabbit Grimace Scale)

• body condition (we will revisit this on the hands-on exam as well)

• visible changes to the coat and skin.

Sometimes, rabbits will be too stressed to come out on their own, or will attempt to flee when removing them from the carrier or kennel. In these cases, it may be prudent to administer a mild sedative. Oral options are gabapentin and trazodone if ample time is available, or if injectable is indicated, butorphanol and/or midazolam administered IM is typically adequate. If I observe dyspnea, I will often administer a light dose of midazolam and place the patient in oxygen in a quiet area for 20-30 minutes before I attempt a full exam.

Inquisitive, comfortable rabbit (ears perked, eyes wide open)

After the observational exam, I start my physical exam with the pet facing away from me, often with the head tucked in a towel or between my assistant’s arm and body in a football hold. I auscult both the heart and lungs, sometimes lifting them slightly off the table if heart sounds are muffled in the initial position, and then move on to the abdomen. Our small mammal friends are like horses and ruminants - we need to listen for gastrointestinal borborygmi. I like to listen in each ‘quadrant’ of the abdominal cavity and you should be able to hear a gurgle every 15-30 seconds. Stress can reduce GI sounds, so if the rabbit appears otherwise normal on physical exam, a slight reduction may not be a concern as long as the rabbit is eating and defecating regularly. This will become easier the more physical exams you do - you have to know ‘normal’ to know abnormal, and after awhile you will be able to easily detect hypo- and hyper-motility.

This rabbit wanted to stretch out and was a 'less-is-more' rabbit when it comes to restraint. However, if it is an unfamiliar rabbit, make sure your assistant has adequate control to prevent the rabbit from jumping or lunging by placing their hands in front of/on top of each shoulder blade.

While the rabbit is still facing away from me, I begin my palpation by gently running my hands over the rabbit's body to assess body condition, palpate in the fur for any skin lesions or masses and palpate the lymph nodes. After palpating along the superficial thorax and abdomen, I progress to palpating along the mandible and ventral neck, palpating for any lymph node enlargement and swellings along the mandible. I check the compliance of the thoracic cavity by gently compressing the sternum - if there is concern for decreased compliance, I will have the assistant turn the rabbit’s head towards me and gently tilt the front of the rabbit toward the ground to check for positional exophthalmos. 

Abdominal palpation should reveal a soft, malleable stomach, typically not extending beyond the rib cage, and a large, pliable cecum taking up the majority of the abdominal cavity. Borborygmi can often be appreciated when running the intestinal contents and cecum through your fingers. The liver is often not palpable due to the predominance of the GI tract and should not extend beyond the margins of the rib cage. The kidneys are present along the dorsal body wall on either side of the spine, with the right kidney typically located more cranially. They are somewhat more mobile than our small animal counterparts. If the cecum is prominent, it may not always be possible to feel both kidneys. The urinary bladder can be felt in the central caudal abdomen and should be cautiously palpated as cases of rupture on rough palpation have been documented. It can be normal for a small amount of calcium salts, or bladder sludge, to be palpable in the ventral bladder or visible on expression. 

Abdominal cavity anatomy and orientation, from: Varga Smith M ed. Textbook of Rabbit Medicine. 3rd ed. Poland: Elsevier Limited; 2023.

In females, the uterus and ovaries are typically not palpable unless enlarged. However, uterine neoplasia is so common in rabbits over a year of age, it is often appreciated in entire females. After abdominal palpation, I lift the tail to examine the rectal mucosa and take a rectal temperature. The rectal mucosa is very friable so exercise caution. 

Then I like to check each limb for normal range of motion and for any crepitus/clicking at each joint. Make sure your assistant is supporting the front end of the rabbit when examining the rear limbs - many rabbits try to move forward when taking their rear limbs through range of motion. 

With the assistant holding the rabbit against their body with one hand supporting the thorax and the other supporting the hindquarters, the ventral surface of the rabbit can be examined.  

Assistant restraint with one hand supporting hindquarters and other supporting thorax. Note that this rabbit is extremely overweight.

Intact males should have a visible scrotal sac on either side of the caudally located penis on the caudoventral pelvis. Testicles should descend by about 12 weeks of age, however, rabbits have open inguinal canals and many rabbits can retract their testicles abdominally when stressed. If intact males have retracted their testicles, they can often be gently massaged caudally into the scrotal sacs utilizing gravity. Cryptorchidism is uncommon, but it does happen! If you can’t manipulate the testicles into the scrotal sac, it is possible that you will be able to once the animal is under sedation, and if not - you may have a true cryptorchid patient!

Males neutered at a young age often have minimal scrotal sac development but can be easily sexed by gently extruding the penis. The rabbit penis has a round opening while the vulva is a linear orifice.

Comparing a female to a neutered adult male.

Mature intact females often have a rather prominent vulva and mammary glands can typically be appreciated on either side of the ventral abdomen. They also typically develop a large dewlap; if a female is spayed later in life, it may never fully regress. Males do have nipples, but they are typically not appreciable unless searched for. 

Intact female rabbit with a large dewlap

While the rabbit is held in this position I check for perineal soiling (urine staining, clumped fecal material or cecotrophs in fur) and examine the scent glands on either side of the genitals for impaction or infection. There is often a small amount of odorous brown or yellow waxy debris built up in each fold of skin. This can be gently cleaned out with moistened cotton-tipped applicators. 

Then I examine the palmar and plantar surfaces of each limb. The plantar surface of each hindlimb may have a narrow hairless tract - this can be totally normal, but make sure there are no crusts, swellings or open wounds present. Check each digit for swelling/discharge/redness around the nail base, abnormal nail growth or abnormal range of motion. 

I also examine the medial aspect of the forelimbs for any crusts or discharge. Rabbits groom their face with their front paws, so they will often build up discharge in this location if they are still grooming regularly. I sometimes see this even if they don’t have nasal discharge as the first sign of upper respiratory issues. 

Young rabbit with nasal discharge, discharge on medial forelimbs and soiled perineum.

Lastly, I have the assistant place the rabbit back on the non-slip mat with the head towards me and I examine the face and oral cavity. The face should be free of discharge and appear symmetrical. I gently palpate along the cheeks feeling for any swellings or cheek teeth spurs, along the zygomatic arch and around the base of the ears. I check for pupillary light and dazzle reflexes. Direct PLR is much more reliable than consensual in rabbits, but is often slower and weaker than what we are used to in other small animals. 

I use an ophthalmoscope to evaluate internal ocular structures. It is fairly common for older rabbits to have immature cataracts or lenticular sclerosis; rabbits affected by Encephalitozoon cuniculi in utero can develop cataracts with subsequent phacoclastic uveitis at any age. 

I use an otoscope with the largest cone that the ear canal will comfortably accommodate to visualize the outer ear canal. It is common for lop eared rabbits to have a moderate amount of white to pale yellow waxy exudate that can resemble purulent debris. You can determine which you are dealing with by examining microscopically. Wax will have minimum cellularity and bacteria, while purulent exudate is often rampant with bacteria and heterophils. I can often very carefully visualize the eardrum in non-lop eared rabbits by gently grasping the ear near the base and using gentle pressure to straighten the bend in the canal, however, it is nearly impossible in lops due to the bend in their ear canals. If the rabbit seems uncomfortable at all, I discontinue and proceed with sedation if a full otic exam is indicated. 

Thick, proliferative crusts are sometimes present, indicating likely Psoroptes cuniculi infection. If the canal is not obstructed, I can often see mites moving in the canal using the otoscope. If confirmation is needed, you can use a dry cotton tipped applicator or remove a small flake of the crusts (try not to remove directly from skin as it is very painful!) and examine the debris microscopically with a small amount of mineral oil. 

Rabbit with severe Psoroptes infestation affecting both ears and the facial/neck skin

The oral exam consists of much more than just a visual exam. I start by gently moving the lower jaw laterally back and forth relative to the remainder of the skull to evaluate cheek teeth occlusion. The teeth should slide back and forth without catching. I also move the jaw vertically and slightly front-to-back to ensure appropriate range of motion of the temporomandibular joint. I lift the lips and visually examine the occlusal surface of the incisors from the rostral aspect and lateral aspect. The upper incisors have a beveled edge where they occlude with the lower incisors at a 45 degree angle. A pair of small peg teeth are located behind both upper and lower incisors. At rest the lower incisors should sit between the caudal upper incisors and upper peg teeth. I check the skin around the mouth for salivary staining or facial fold erythema. 

Normal length and occlusion of upper and lower incisors

An abbreviated oral exam can be performed on most animals, but sedation or full anesthesia is indicated for a full oral exam. Otoscopes with a plastic cone have been used historically, but if you are going to see exotics regularly I highly recommend investing in a bi-valve nasal/oral speculum. These provide a much wider range of view when utilized. I make sure my assistant has adequate restraint and then use my left hand to gently stabilize the head. With my right (dominant) hand, I place the speculum in the diastema and gently open it. In small rabbits, you can often view all four dental arcades at once, but in larger rabbits I will often look at one side at a time. 

Utilizing a bi-valve nasal speculum to examine the cheek teeth of a rabbit (Note that this rabbit's left lower cheek have been previously extracted and the upper cheek teeth are longer than they would be with normal apposing teeth)

The cheek teeth should have a slight angle to the occlusal surface with the ventral cheek teeth appearing longer lingually and slanting to a shorter edge buccally. The maxillary cheek teeth reflect the reverse. This should not be mistaken for cheek teeth spurs or points. The cheek teeth appear somewhat uniform but in older rabbits may display some darkening in the folds of the teeth. The length of the dental crowns should be symmetrical from side to side. The presence of swelling, abrasions, blood, a foul odor or purulent discharge is abnormal. If dental disease is suspected, the rabbit should be sedated or anesthetized for a complete oral exam and skull and dental radiographs or computed tomography.  

Graphical depiction of rabbit cheek teeth occlusion, note the slight angle of occlusion and appearance of small mandibular lingual spurs and maxillary buccal spurs. From: Quesenberry K, Orcutt CJ, Mans C, et al. eds. Ferrets, Rabbits, and Rodents: Clinical Medicine and Surgery. 4th ed. St Louis: Elsevier, Inc; 2021.

I hope this helps you perform more thorough rabbit physical exams! Let me know in the comments if you have any feedback, questions, or a topic for a future post.

A special thanks to Sarah Cox, DVM for contributing photos for this post.

One of the most difficult things about being an exotic animal vet is knowing where to find the most up to date and applicable information. There is no way each of us can hold the entirety of knowledge pertaining to anatomy, physiology, therapeutics, diagnostics, and so on for dozens, if not hundreds of species, which is where knowing how to use your resources comes in. 

There are so many helpful resources out there, and textbooks are just one of them, but arguably the most important for a solid basis of exotics knowledge. This list just scratches the surface, but includes the texts I have found to be overall most useful for a variety of species. Keep in mind, with exotic animals, new research is published weekly and so even the best textbooks can become outdated quickly. It’s never a bad idea to do a quick PubMed® or Google Scholar™ search to make sure there is no newer data out (or use my consultation services and I’ll keep you up to date on the latest literature!). 

**Click the links to purchase any of these books (This page contains affiliate links, meaning if you click on them I will receive a small commission at no cost to you)

10. Diagnostic Imaging of Exotic Pets

This atlas offers large radiograph, ultrasound, CT and MRI reference images and the most common visible changes seen with pathologic processes of reptiles, small mammals and avian species. 

9. Exotic Animal Laboratory Diagnosis

Covers obtaining samples, selecting tests, and interpreting results for small mammals, a variety of avian species, primates, reptiles and aquatic animals

8. Exotic Animal Hematology and Cytology

This book contains excellent images of the unique features of different hematology and cytology findings of exotic animal species as well as multiple case studies exploring common clinical problems. 

7. Exotic Animal Emergency and Critical Care Medicine

This resource deals with management of the most common ER presentations of birds, reptiles/amphibians and exotic companion mammals, exploring triage/stabilization, diagnostics, treatment, cardiopulmonary resuscitation and euthanasia. 

6. Surgery of Exotic Animals

The first surgery textbook specifically written for exotic species for practitioners with a basic working knowledge of surgical principles in domestic small animals. This book includes written descriptions of a variety of procedures and is supplemented with color images of regional anatomy and the procedures themselves. 

5. Current Therapy in Exotic Pet Practice

Comprehensive overall reference to diagnosing and treating disease in exotic pets broken down by body system.

4. Mader’s Reptile and Amphibian Medicine and Surgery

The most comprehensive resource on reptile and amphibian medicine. I will be the first to say I loathed the 2nd edition of this text: the layout was awful, it went into significant depth on some rare disease processes and then skipped over more common ones entirely, and the index was a pain. The addition of Drs. Divers and Stahl as editors improved on these problems immensely, and I find this a much less frustrating version. 

3. Current Therapy in Avian Medicine and Surgery 

Succinct summary of how to approach, diagnose and treat most avian medical and surgical issues, covering a variety of species.

2. Ferrets, Rabbits and Rodents: Clinical Medicine and Surgery

AKA the ‘pink book’ AKA ‘the bible of small mammal medicine’. IYKYK. If you are going to dip even a pinkie toe into the world of exotic companion mammal medicine, this is the book you need. Even with 10 years treating these species, I still reach for it regularly and it is probably my second most-used textbook. 

1. Carpenter’s Exotic Animal Formulary

This is the book I reach for on a daily basis! It has medication dosages for most exotic animal species that you will see in practice, as well as common protocols, husbandry information and reference values. It is invaluable and a must-have if you are going to see any exotics. 

Honorable Mention:

Backyard Poultry Medicine and Surgery: A Guide for Veterinary Practitioners

While poultry is touched on in some of the above resources, this text is much more comprehensive, so I recommend it if you are seeing more than the occasional chicken or duck. 

Later on, I’ll get more in depth and break down my top 5-10 books for each species group. Do you agree or did I leave out your favorite textbook? Let me know in the comments below and subscribe to my email list for the latest updates and access to FREE resources.