Topics in Medicine and SurgeryTopics in Medicine and Surgery

Standards of Care in the 21st Century:The Rabbit

Peter G. Fisher, DVM

considerat

22

Abstract

State-of-the-art improvements in how we feed and provide medical and surgicalcare for the rabbit (Oryctolagus cuniculus) have resulted in a greater lifespan for thiscommon pet animal. The rabbit consultation should begin with a discussion onhusbandry, behavior, and nutrition, and then should be followed by a thoroughpatient history and physical examination. Having a support staff that can help withclient education, patient restraint, and diagnostic sample collection, along withappropriate use of diagnostic equipment and knowledge of common rabbit healthissues, demonstrates a hospital’s proficiency in rabbit medicine. Proper use ofsedation and analgesia, and knowledge of the basic critical care needs and methodsfor fluid therapy in rabbits, will improve patient treatment and case success. Areview of the diagnostic workups and therapeutic plans associated with commonrabbit illnesses will help the veterinary practitioner develop a comfort level andexpertise with this unique species. Copyright 2010 Elsevier Inc. All rights reserved.

Key words: critical care; fluid therapy; medical therapy; Oryctolagus cuniculus; phys-ical examination; rabbit

State-of-the-art improvements in how we feedand provide medical and surgical care for thepet rabbit (Oryctolagus cuniculus) has resulted

in a healthier and longer lifespan for this commonpet animal. The rabbit is the most popular exoticanimal patient seen in the author’s small animal andexotics practice, and many rabbit owners are dedi-cated to excellent health care for their pets. Allhospital team members need to be aware of a rab-bit’s anatomical and physiological parameters so thatwhen a patient is presented for an illness or to havea surgical procedure performed, they will be awareand can meet the special needs of these animals.Hind-gut fermentation, unusual calcium metabo-lism, teeth that continue to grow for most of therabbit’s life, a very small thoracic size in comparisonwith body mass, high metabolic rates, and being acatecholamine-driven prey animal that stresses easilyare all special factors that need to be taken into

ion when practicing rabbit medicine.

Journal of Ex

The Office Visit and Physical Examination

Client communication begins with the receptionist,who not only needs to know the required routinehusbandry recommendations of raising a healthyrabbit, but must also recognize the signs of commonillness. The receptionist should be the staff memberwho decides when to schedule the rabbit patient andunderstands the critical nature of certain diseaseproblems (e.g., gastrointestinal [GI] or neurologicdisease) that affect these animals.

From the Pet Care Veterinary Hospital, Virginia Beach, VAUSA.

Address correspondence to: Peter G. Fisher, DVM, Pet Care Veter-inary Hospital, 5201-A Virginia Beach Blvd, Virginia Beach, VA23462. E-mail: pfisher@petcarevb.com.

© 2010 Elsevier Inc. All rights reserved.1557-5063/10/1901-$30.00

doi:10.1053/j.jepm.2010.01.004

otic Pet Medicine, Vol 19, No 1 ( January), 2010: pp 22-35

Standards of Care: The Rabbit 23

When a rabbit is presented to the veterinary hos-pital, all first-time clients should be offered a generallesson on husbandry, behavior, and nutrition as partof the initial examination. The author’s employeesuse prepared folders filled with rabbit-dedicated cli-ent education handouts to address various topicsthat help engage the client on proper rabbit care.These handouts are also required reading for all staffmembers, so that they are able to initiate these in-valuable husbandry discussions. Having a supportstaff that can help with client education, patientrestraint, and diagnostic sample collection demon-strates a hospital’s proficiency in rabbit medicine.

A routine physical examination should includeinspection of the ears, nares, and eyes; abdominalpalpation; auscultation of the heart, lungs, and ab-domen (e.g., gut sounds); and visual examination ofthe fur and dermis including the perineum and footpads. For pharmacological dosing and monitoringbody condition scores, a digital scale that can mea-sure precise weights in grams and kilograms is essen-tial. Each examination room should be stocked withtowels in a variety of sizes to aid in patient restraint,help ensure the animal’s footing on an examinationtable, and prevent heat loss on stainless-steel or lam-inate examination tables. Some practitioners preferto use a rubber bath mat with suction cups on theexamination table. The rubber provides traction andincreased security for anxious rabbits and is easilycleaned and disinfected. For restraint, a small bathtowel may be gently wrapped around the rabbit’sbody so that it feels secure and can be examinedwithout struggling (e.g., “bunny burrito”). Whentransporting a rabbit, its body should be supportedand the back feet controlled with one arm while theopposite hand supports the chest between the frontlegs. The goal is to do this in a calm, soothingmanner so that the rabbit will not be stressed. Fe-line/rabbit nail trimmers are recommended for allstaff members to encourage nail trims. For initial den-tal examinations, a small animal otoscope or an illumi-nated Welch Allyn (Welch Allyn, Inc., SkaneatelesFalls, NY USA) bivalve speculum can be used (Fig 1).The author has a separate set of otoscope cones setaside for this purpose, because the gnawing actionduring an oral examination will damage the plastic,leaving rough edges. Magnification head loupes willsignificantly enhance viewing of the skin and otherlesions.

Nutrition

As a general rule, rabbit owners are likely to seek

additional information regarding their pet; therefore,

a discussion on rabbit GI physiology and how dietaffects the overall well-being of the rabbit is often help-ful in enhancing a veterinarian’s credibility. An under-standing of the rabbit’s unusual digestion as a hind-gutfermenter, and the role of fiber in maintaining thephysiologic balance of the digestive process, will helpexplain the potential complexities involved when con-sidering recommendations on nutrition.

Ultimately, a diet with 20% to 25% fiber, low starch,and appropriate protein levels will reduce the inci-dence of many GI problems. As a general rule, a main-tenance diet of 1 ounce of high-fiber (�20%), low-protein (�16%) pellets per kilogram of body weightand ad libitum grass hay (e.g., timothy, oat, orchardgrass, meadow) is recommended. Showing clients abag of food that meets the nutritional requirements oftheir pet rabbit provides a more memorable impres-sion of the recommended product(s) than a generaldietary discussion without visual aids. Oxbow AnimalHealth (Murdock, NE USA; www.oxbowanimalhealth.com) supplies the veterinary market with a variety oflegume and grass hays and pelleted diets for the rabbitthat are within the recommended nutritional require-ments mentioned above. The availability of fresh, leafygreens at a veterinary hospital gives one the opportu-nity to show clients appropriate produce that canenhance a rabbit’s diet and also serve as an aid inevaluating the anorexic patient in suspect ileus cases.For nutritional support of anorexic rabbits, OxbowCritical Care for Herbivores (Oxbow Animal Health)can be syringe fed and is an excellent source of fiber

Figure 1. A Welch Allyn bivalve speculum can be used for rabbitoral examinations as part of the initial physical examination. If anoral health problem is suspected, clients should be educated onthe need for general anesthesia to perform a thorough oralexamination.

and nutrition.

24 Fisher

Diagnostic Testing

Clinical PathologyOn completion of the history and physical examina-tion, a veterinarian may choose to initiate a diagnos-tic workup; it is recommended to select diagnostictesting equipment that is best suited to the exoticmammal patient. Clinical pathology remains an im-portant diagnostic tool with rabbits, because it en-ables the clinician to evaluate many different systemswithin their patient. The maximum amount of bloodthat can be safely collected from a “healthy” stablerabbit for diagnostic purposes is 1 mL/100 g bodyweight; the blood volume of the adult rabbit is 55 to65 mL/kg.1 Venipuncture options include the jugu-lar, lateral saphenous, cephalic, and marginal earveins. The lateral saphenous vein is the author’spreferred site for sample collection. For sample col-lection, a 1-mL tuberculin syringe with a 25-gauge �5/8-inch (0.50 � 16-mm) needle can be used. Alter-natively, Monoject (Tyco Health care Group, Mans-field, MA USA) offers a 0.5-mL tuberculin syringewith an attached 28-gauge (0.36-mm) needle thatmay simplify blood collection from the cephalic orlateral saphenous veins in the smaller dwarf breeds.The size of many exotic mammal patients will limitthe total volume of blood that may be obtained atany one time; therefore, working with diagnosticequipment that is calibrated for companion exotic

Figure 2. (A) The VetScan VS2 Chemistry Analyzer (Abaxis, Unionto provide a chemistry panel calibrated for a variety of exotic mammacan be calibrated to provide complete blood count information on ra

other predominant inflammatory cell.1

mammals and yields the greatest amount of informa-tion from small volumes of blood is ideal. Our hos-pital performs virtually all routine rabbit plasmachemistry panels, complete blood counts, and urineanalyses in-house, which offers the advantage of hav-ing same-day results and a more rapid response withinitiating a treatment plan (Fig 2, A and B). Alter-natively, many commercial laboratories offer next-day service for the same blood analyses that can beobtained with in-house equipment. For in-housechemistry analyzers requiring serum, the StatSpinMP Centrifuge (Iris International, Inc., Chatsworth,CA USA) is recommended because it is designed toefficiently centrifuge small volumes of blood (up to2 mL) and maximize serum yields. It can also beused on small volumes of urine to obtain sedimentsamples for cytological review. For blood cultures,Septi-chek BBL 20 mL (pediatric) collection vials(Becton Dickinson, Franklin Lakes, NJ USA) can beused.

SerodiagnosisMost commercial veterinary diagnostic laboratories useenzyme-linked immunosorbent assays (ELISA) for se-rologic testing of rabbit diseases. Several veterinarydiagnostic laboratories that primarily serve the labora-tory animal research community offer DNA-basedassays (e.g., DNA amplification polymerase chain reac-tion) and multiplex fluorometric immunoassays in ad-

A USA) is capable of using 100-�L whole blood or serum/plasmacluding the rabbit. (B) The Abaxis VetScan HMII hematology analyzer. Healthy rabbits are generally lymphocytic, with heterophils as the

City, Cls, inbbits

Standards of Care: The Rabbit 25

dition to ELISA testing to screen for disease in researchand biotechnical facilities. The sensitivity and specific-ity of the different serologic tests can vary with thedisease in question and the modality used. For the petrabbit practitioner, single rabbit samples are acceptedby several laboratories (e.g., University of Miami Com-parative Pathology Laboratory, Miami, FL USA; SoundDiagnostics, Woodinville, WA USA) for serological test-ing (Table 1). Paired titers to demonstrate active dis-ease are ideal to help confirm a diagnosis with thisdiagnostic testing modality.

ImagingDigital radiography has revolutionized the diagnosticvalue of radiographic images; however, even with theenhanced technological improvements associated withthis modality, there are many determinants that canaffect image quality and one’s ability to properly assessthose images. The hardware and software used to gen-erate images will have a dramatic effect on image qual-ity. Image quality is also dependent on the veterinarypersonnel’s knowledge of the system (e.g., software)and ability to properly use it. Some digital radiographysystems are very easy to use, whereas others are not. Itis important that the equipment is capable of produc-ing images that have excellent anatomic detail. High-quality images are especially important when evaluat-ing the skull. Diagnostic imaging can be especiallyvaluable for assessing the GI, urogenital, respiratory,cardiac, and skeletal systems, and as part of an overalloral health assessment.

Sonographic examinations record echoes of ultra-sonic wave pulses directed into tissues and reflected bytissue planes where there is a change in density. Ultra-sonography is a dynamic modality, and the Dopplerunit is especially useful in assessing cardiac contractilityand blood flow. A fluid:gas interface creates a highlyreflective surface, which causes an artifact called rever-beration. Reverberation makes imaging through gas/

Table 1. Sound Diagnostics, Inc. offersELISA serologic screening for detectionof antibodies to the following infectious

diseases of rabbitsAgent Disease

Clostridium piliforme Tyzzer’s diseaseEncephalitozoon cuniculi EncephalitozoonosisPasteurella multocida PasteurellosisTreponema cuniculi Syphilis

air difficult because it is impossible to distinguish these

artifacts from real echoes. Abdominal ultrasonographyis more challenging in rabbits because of fluid:gasartifacts, along with the large size of the herbivorececum. It is vital that the ultrasonographer be familiarwith both the practice of ultrasonography as well as thenormal anatomy of rabbits. For most rabbits, a high-frequency transducer with a footprint of less than 2 cmis required. Ultrasonography is used most often by theauthor for assessment and diagnostic sampling of skull,abdominal, and thoracic masses/abscesses, and for car-diac disease evaluation (Fig 3, A and B).

Critical Care

Fluid TherapyAs the level of rabbit medicine and surgery has ma-tured and become more sophisticated, so has theneed for appropriate intravenous fluid therapy andpatient monitoring. Physiological stabilization of apatient should be the goal of every case, whether asso-ciated with illness or surgery. Catheterization with a 24-to 26-gauge (0.56-0.46 mm) indwelling intravenous(IV) catheter in the cephalic vein is routinely per-formed in rabbit patients (Fig 4). Alternatively, forshort-term IV access, a 26-gauge (0.46 mm � 19 mm)winged IV catheter can be placed in the caudalauricular vein. The catheter can be secured to thepinna by applying a small amount of tissue adhesiveon the catheter wings and then pressing themagainst the skin. If one is unsuccessful at passing anIV catheter or if the peripheral veins have collapsedas a result of the patient’s condition (e.g., severe dehy-dration, shock), then intraosseus catheterizationshould be considered. A 22-gauge (0.72 mm � 3.81cm) spinal needle inserted into the humerus via thegreater tubercle will provide a direct route for fluidadministration. The type of fluid selected for a pa-tient will vary depending on serum chemistry andelectrolyte results, underlying metabolic disease, andduration of therapy. The rate of fluid administrationwill vary based on the daily requirements of thepatient, its current hydration status, presence of un-derlying metabolic disease (e.g., renal disease, car-diac disease), and daily fluid loss. The goal of fluidtherapy is to provide necessary fluid and electrolytes,meet metabolic demands, and restore intracellularwater balance until the patient is eating and drinkingon its own or recovered from surgery. The durationof treatment will vary from case to case dependingon the patient’s health, treatment response, and/orrecovery from a surgical procedure. An infusionpump is a necessity in the accurate administration of

maintenance fluids at rates of 4 to 10 mL/kg/h.

26 Fisher

Recognition and Treatment of ShockIn severely ill rabbits, fluid losses need to be treatedaggressively, or early decompensatory shock may de-velop. Clinical signs of early decompensatory shockin rabbits include hypothermia, prolonged capillaryrefill time, pale mucous membranes, cool limbs and

Figure 3. (A) Newer, portable ultrasonography units, such as the GEallowing for more affordable sonograms in private practice; thisrespiratory distress.

Figure 4. Most calm rabbits tolerate intravenous catheterizationwith sedation and local subcutaneous infiltration of lidocaine. Forreplacement fluids, the author uses an isotonic crystalloid solutionsuch as Plasmalyte-A (Baxter Healthcare, Deerfield, IL USA) or 0.9%saline solution (Baxter Health care) with or without added dextroseto form a 2.5% or 5% solution. An intravenous fluid warmer, such asthis TempCare unit (Elltec Co. Ltd. Nagoya, Japan), will aid inmaintaining patient thermoregulation and maximize patient recovery

from surgery or illness.

skin, bradycardia, and hypotension.2 Both crystalloidand colloid fluid products may be required duringtreatment; the determination for this will depend onpatient condition, blood pressure and serum chem-istry results.

A fluid resuscitation plan, to restore tissue perfu-sion and oxygenation, needs to be developed whileconsidering the type, quantity, and rate of fluid to beadministered. The primary goal of a fluid resuscitationplan should be to administer the smallest volume offluid required to eliminate or prevent clinical signsassociated with decompensatory shock.2 Resuscitationof hypovolemic shock is best accomplished with a com-bination of crystalloid and colloid fluid products.Crystalloid fluids are primarily comprised of waterand have a sodium or glucose base, along with asmaller concentration of other electrolytes or buff-ers.3 Crystalloid fluid products are capable of distrib-uting to all body compartments, and thus replaceboth interstitial and intravascular fluids losses. Col-loid fluid products contain large molecular weightsubstances that, in general, are not able to passthrough capillary membranes and aid in the expan-sion of intravascular volume. Examples of colloidfluid products include whole blood or plasma,Hetastarch (Braun Medical, Irvine, CA USA), Dextran70 (Pharmacosmos A/S, Holbaek, Denmark), andOxyglobin (Dechra Veterinary Products, OverlandPark, KS USA). When a colloid product is used in

Q Book XP (GE Health Care, Buckinghamshire, United Kingdom), arec image (B) was obtained from a rabbit with chronic low-grade

LOGIcardia

combination with a crystalloid product, there can be

Standards of Care: The Rabbit 27

as much as a 40% to 60% reduction in the total fluidvolume required for resuscitation than if a crystal-loid was used alone.2

A summary of the therapeutic approach for rab-bits in decompensatory shock is as follows2:

● Administer a bolus infusion of isotonic crystal-loid fluid product at 10 to 15 mL/kg.

● Administer Hetastarch at 5 mL/kg over 5 to 10minutes.

● Monitor systolic blood pressure; once greaterthan 40 mm Hg, administer maintenance crystal-loids (Fig 5).

● Aggressively warm patient with a forced-air heat-ing system such as the Bair Hugger (ArizantHealth Care, Eden Prairie, MN USA).

● Monitor rectal temperature until it approaches98.0°F (37°C); recheck blood pressure and ad-minister a crystalloid product (10 mL/kg) withOxyglobin at 2-mL/kg increments (repeatedover 15 minutes) until the systolic pressure in-creases to greater than 90 mm Hg.

● Begin rehydration phase of fluid resuscitationonce systolic pressure is consistently greater than90 mm Hg.

Figure 5. Indirect blood pressure monitoring by the Doppler methodis preferred by most veterinarians. Doppler flow detection (ParksMedical Electronics, Inc., Aloha, OR USA) uses ultrasonic waves foraudible monitoring of arterial blood flow, and in the rabbit the frontlimb is more reliable and most commonly used. The transducerprobe crystal is placed in a bed of ultrasound gel on the shavedmedial midshaft of the radius-ulnar area to assess blood pressure ofthe radial artery. Ideally, a cuff size approximately 40% of thecircumference of the humerus is used to measure indirect blood

pressure in rabbits.

● Continue a constant-rate infusion of Oxyglobinat 0.2 to 0.4 mL/kg/h during the rehydrationphase.

Analgesia, Sedation, and AnesthesiaPatient sedation and pain control are a necessarypart of a daily rabbit practice. Whether treating pain-ful conditions such as GI stasis, dental disease, ortrauma, or premedicating for an oral examination orgeneral anesthesia, the rabbit patient benefits fromknowledgeable and judicious use of analgesic agentsand sedatives.

Confirming the presence of pain in animals is diffi-cult because of differences between and within speciesin the behavioral response to noxious stimuli.4 Manybehaviors are consistent with, but not invariably in-dicative of, pain, and confirming the presence ofpain in an animal may be complicated by the factthat normal behavior is not always indicative of apain-free state.4 Like humans, rabbits show individ-ual variability in both their pain threshold and tol-erance, and recognition of pain in rabbits relies onskill, experience, and professional judgment of thepatient. The following are behavioral changes thathave been used in the assessment of pain in rab-bits4,5:

● Searching/exploring behavior; frequency andduration

● Movement frequency and duration

● Food consumption, duration

● Grooming behavior, duration

● Conspecific interaction, duration

● Changed posture, tucking of abdomen, tensingof muscles

● Guarded or aggressive behavior

● Attempting to hide

● Squinting of the eyes

● Grinding of teeth

Nociception is the neural response to the appli-cation of a noxious stimulus. The process of noci-ception and pain involves multiple steps and path-ways. An effective pain management plan includesdrugs of different classes that act at different path-way locales, a process known as multimodal analge-sia. This approach allows for smaller doses of eachdrug to be used because the effects are additive or

synergistic, and thus reduce the undesirable side

28 Fisher

affects expected when larger doses of individualdrugs are used alone.6 Multimodal preemptive anal-gesia with opioids, nonsteroidal antiinflammatorydrugs, alpha-2 agonists, dissociatives, or local anes-thetics (Table 2) will prevent the “wind up” effect ofsurgical pain that occurs when neurons that mediatenociception in the dorsal horn of the spinal cord arerepeatedly stimulated.

To alleviate the apprehension and stress associ-ated with the hospital environment, rabbits shouldbe given a sedative 20 to 30 minutes before anyprocedure requiring restraint or anesthesia. The au-thor routinely uses midazolam (Baxter Health CareCorp., Deerfield, IL USA) (Table 2) for a variety ofdiagnostic procedures and outpatient treatmentsthat include imaging, blood or cytological specimencollection, and grooming procedures. Used beforesurgery, sedatives contribute to fewer complicationsassociated with anesthetic induction, anesthesia it-self, and recovery. For surgery patients, analgesic

Table 2. Published doses of preanesthetics,in bold print are ones commonly

Drug Dosage (mg/kg)

Midazolama 0.25-0.50 IM orIV

Antianopio

0.5-2.0 IM WhenButorphanolb 0.2-0.8 IM, IV, SQ OpioidBuprenorphinec 0.02-0.06 IM OpioidOxymorphoned 0.05-0.2 SQ or IM OpioidDexmedetomidinee 0.1-0.2 IM/IV �-ago

comMeloxicamf 0.3-0.5 SQ/PO NSAIDLidocaineg 2% 1.0 Local

bupBupivicaineh 0.5% 1.0 Local

forKetaminei 1.0 IM (low dose) Prean

IM, Intramuscularly; IV, intravenously; SQ, subcutaneously; PO, oraMidazolam, 5 mg/mL, Baxter Healthcare Corp, Deerfield, IL USA.bTorbugesic, 10 mg/mL, Fort Dodge Animal Health, Fort Dodge, IAcBuprenex, 0.3 mg/mL, Reckitt Benckiser Pharmaceuticals Inc, RichdNumorphan, 1 mg/mL, Endo Pharmaceuticals Inc, Chadds Ford, PeDexdomitor, 0.5 mg/mL, Pfizer Animal Health, New York, NY USAfMetacam, 5 mg/mL, Boehringer Ingelheim VetMedica Inc, St JosephgLidocaine 20 mg/mL, Agri Laboratories, St Joseph, MO USA.hMarcaine 5 mg/mL, Hospira, Lake Forest, IL USA.iKetaset, 100 mg/mL, Fort Dodge Animal Health, Fort Dodge, IA USFrom Flecknell PA: Analgesia of small mammals. Vet Clin North AmSedation and anesthesia in exotic companion mammals. Proceedings oKo J: Anesthesia and analgesia for small mammals and birds. Vet C

agents should also be given preemptively, because

inhalant anesthetics produce unconsciousness butare not recognized for their analgesic effect. Well-recognized benefits of preanesthetic agents include:1) reduced stress associated with restraint and induc-tion, and 2) lowering of the mean alveolar concen-tration of inhalant agents required to achieve a sur-gical plane of anesthesia.

Medical Therapy

Various diseases and health problems are unique tothe rabbit. The following is a summary of severalcommon medical problems and the standards ofcare in developing a diagnostic and treatment planfor these presentations.

Respiratory DiseaseRespiratory disease is a common finding in captiverabbits. Rabbit patients that present with recurrent

sthetics, and analgesics. Drugs highlightedby the author in rabbit patients

Comment

tranquilizer, preanesthetic; use in combination with anr ketamine

alonelgesiclgesiclgesic, preop with midazolam or for additional analgesiapreop sedation and analgesia; preanesthetic; can be

d with ketamine; can be reversed with atipamezolery 12 h for analgesiathetic—rapid onset; can be used in combination withine for longer analgesiathetic—slower onset; can be combined with lidocainer analgesiaetic and for additional sedation

SAID, nonsteroidal antiinflammatory drug.

VA USA.A.

USA.

c Anim Pract 4(1):47-56, 2001; Hernandez-Divers SJ, Lennox AM:ciation of Avian Veterinarians, pp 287-298, 2009; Lichtenberger M,orth Am Exotic Anim Pract (10)1:293-315, 2007.

aneused

xietyid ousedanaanaana

nist,bine, eveanesivicaaneslongeeseth

ally; N

USA.mond,A US., MO

A.Exotif Assolin N

upper respiratory disease and nasal discharge

Standards of Care: The Rabbit 29

should have a rigid endoscopic examination of thenasal passages to obtain biopsies and other diag-nostic samples for histopathology and microbial(e.g., fungal, bacteria) culture and antimicrobialsensitivity testing. Ultrasonic nebulization is a worth-while adjunct therapy if pneumonia is suspected (Fig6). Although there are a number of different diagnos-tic tests that can be used to assess the respiratory systemof a rabbit, one that is only recently being advo-cated is capnography. A recent report demon-strated that rabbits with respiratory disease canhave elevated end-tidal CO2 levels compared withnondiseased rabbits, and that this test may proveuseful in the future for veterinarians looking toassess the physiologic status of a rabbit with respi-ratory disease.7

Gastrointestinal StasisGI stasis is a syndrome where the normal muscularcontractions of the stomach and intestines aregreatly diminished and, as a result, the normal intes-tinal/cecal bacterial flora is adversely affected (dy-biosis).8 Several factors are usually involved with GIstasis, including environmental stressors, pain fromother underlying conditions (e.g., dental/toothpoints or spurs), and inappropriate diet. Feedingsimple carbohydrates (e.g., breadstuffs or cereals)along with a lack of crude fiber can predispose rab-bits to GI stasis. In the absence of adequate fiber, theGI tract has a reduced motility, which may result insubsequent changes in cecal pH, fermentation pro-

Figure 6. Most rabbits tolerate nebulization via a face mask for 10-to 15-minute sessions with saline solution, antibiotics, and muco-lytics to ease respiratory tract infection and congestion. Dwarfrabbits with respiratory distress secondary to pneumonia can beplaced in an anesthetic induction chamber for minimal-stress neb-ulization therapy several times a day.

cesses, and bacterial populations. Rabbits with GI

stasis are frequently anorexic or have a reducedappetite. Affected animals tend to produce smallstools or no stools; they display outward signs ofdiscomfort by holding a “hunched-up” postureand/or grinding their teeth (bruxism). Diarrheawith or without mucus may develop. Abdominal aus-cultation may reveal normal or hyperactive gutsounds early in the course of the disease, with de-creased to no gut sounds as the stasis continues.Prompt diagnosis and management improve thechances for full recovery. Rabbits presented in obvi-ous distress with a palpably enlarged, noncompress-ible stomach warrant close monitoring and criticalcare. (Fig 7, A and B)

Depending on the severity of the GI conditionand clinician discretion, a variety of treatment mea-sures may include:

● Abdominal massage: Gentle, deep massage ofthe abdomen to stimulate intestinal contractionsand to break down impacted stomach contents.If diagnosed early in the course of the disease,encourage movement and exercise as a way tostimulate gut motility.

● Fluid therapy with an appropriate type and vol-ume of fluids, and route for administration.

● Analgesics as needed, especially if showing signsof pain or evidence of increased GI gas.

● Syringe feeding an enteral product (e.g., OxbowCritical Care) to provide nutrition and fiber tostimulate GI motility. A nasogastric tube can beused to deliver the enteral. A 5- to 8-Fr Argyletube (Kendall, Mansfield, MA USA) passed ven-trally and medially into the ventral nasal meatusand advanced to the stomach has been found tobe helpful.9

● Appetite stimulants: Vitamin B complex injec-tions or cyproheptadine (Periactin; Merck, WestPoint, PA USA) 1 to 4 mg/rabbit by mouth every12 to 24 hours.

● GI motility stimulants: Prokinetics such as cisapride(available through a compounding pharmacy)dosed at 0.5 mg/kg by mouth every 8 to 12 hoursor metoclopromide (Reglan; Schwarz Pharm., Me-quon, WI USA) at 0.5 mg/kg by mouth or subcu-taneously every 8 to 24 hours.

● Simethicone: To help break down gas bubblesassociated with bloating.

● If an endotoxin-induced gut mucosal injury is sus-pected, consider epidural analgesia to prevent

functional and structural mucosal alterations.10

30 Fisher

Dental DiseaseNumerous writings on rabbit dental disease havebeen published in the past decade, with entire texts(Rabbit and Rodent Dentistry, Zoological EducationNetwork, 2005) and journals (Journal of Exotic PetMedicine 17(2):2008) being devoted to the subject. Itis important to remember the direct association be-tween diet and rabbit dental disease. Feeding therabbit free-choice grass hay stimulates constantchewing action, which helps wear down the contin-

Figure 7. Rabbits with intestinal obstruction can be a diagnostic andtherapeutic challenge. These foreign bodies are most commonly dueto a small trichobezoar or hair-filled cecotroph. Although the duo-denum is the most common site for an obstruction (A), problems canalso occur at the pylorus or ileocecocolic junction.8 Radiographically,affected animals may have a stomach that is filled with gas and/orfluid and food; dilated loops of intestine may also be observedproximal to the obstruction (B). If the obstruction passes through theileocecocolic junction, gas will be seen in the cecum and additionalloops of intestine on serial radiographs. In these cases, the patientshould be treated medically. If the obstruction is not moving, asdetermined by serial radiographs, then the case becomes surgical.If the rabbit is taken to surgery, it is ideal to try and gently milk theobstruction down through the ileocolic junction and into the hind gutinstead of performing an enterotomy because of the thin and friablenature of the rabbit small intestine.8

uously growing incisors, premolars, and molars, and

helps prevent acquired dental disease, primarilypainful molar spurs or points. Metabolic bone dis-ease associated with a poor diet and inadequatecalcium, vitamin D, and natural sunlight has alsobeen incriminated as a cause of malocclusion, over-grown dental roots, and mandibular abscesses.11

The rabbit oral anatomy, including the fleshytongue, buccal skin folds, long and narrow oral cav-ity, and caudally placed cheek teeth, make oral ex-amination of the nonanesthetized patient difficult toimpossible. Fortunately, a variety of special instru-ments have been designed to enhance visualizationof the oral cavity and aid in treatment of dentaldisease in rabbits and smaller herbivorous species.When history and physical examination findings sug-gest dental disease, general anesthesia should beused to thoroughly evaluate the patient’s oral cavity.An overall loss of body condition, decreased appe-tite, digestive disturbances, and ocular dischargemay all be associated with dental disease in thisspecies. The author finds the following invaluable inassessing and treating rabbit dental disease:

● Skull radiographs, preferably 6 views that evalu-ate lateral, ventrodorsal, dorsoventral, rostrocau-dal, and right and left lateral oblique projec-tions, are an invaluable aid in assessing rabbitdental health.

● Use specialized dental tools to aid visualization(Fig 8).

● A stainless-steel spatula (Sontec, Englewood, COUSA), used to move oral soft tissues, allows forvisual assessment of the premolars and molarsand protects the oral mucosa and tongue duringfiling or burring of teeth.

Figure 8. An oral examination can be done in an anesthetized rabbit

by inserting an oral dental speculum and cheek dilator.

Standards of Care: The Rabbit 31

● A diamond-coated rasp (Sontec) may be used tomanually smooth small dental points and spurs.

● Many veterinarians prefer to use a specially de-signed dental platform, the rodent table retrac-tor restrainer (Jorgensen Laboratories, Love-land, CO USA), to allow hands-free elevation ofthe head and opening of the mouth.

● Use of a high-speed dental drill is the preferredmethod of trimming overgrown incisors (Fig 9).

● In those rabbit oral surgery cases in which endo-tracheal intubation will interfere with visualiza-tion and access to the teeth, injectable mainte-nance anesthesia with dexmedetomidine alone(80-120 �g/kg) or in combination with ketamine(25-30 mg/kg) can be used.12,13

● Use of local anesthetic dental blocks. Approachescan be extrapolated from the dog and cat litera-ture; however, it is important to have a strong graspof rabbit skull anatomy. The author uses faster-onset 2% lidocaine (Vedco, Inc., St. Joseph, MOUSA) mixed with slow-onset 0.5% bupivicaine(Hospira, Inc., Lake Forest, IL USA) at a rate of 1mg/kg body weight for each drug and dilutes withsaline solution to a final volume of 1 mL.

● Extraction of the incisor teeth is recommendedfor resolution of persistent malocclusion in rab-bits (Fig 10, A and B).

● Periapical infection with abscessation and osteo-myelitis requires aggressive and prolonged ther-

Figure 9. A high-speed dental drill (IM3 Pty Ltd, Lane Cove, NewSouth Wales, Australia) is the preferred method for trimming or filingovergrown molars or incisors. This tool allows the veterinarian toproperly shape and contour the clinical crown without damaging thereserve crown.

apy (Fig 11, A, B, and C).14-17

● Facial dermatitis as a result of chronic epiphorasecondary to dacryocystitis is not uncommon inthe rabbit. Many times this is in association withelongated incisor tooth roots and blockage ofthe nasolacrimal system. A 23-gauge (0.64-mm)lacrimal cannula can be used to cannulate thepunctum lacrimale in the medial canthus toflush the duct. Infusing saline solution throughthe cannula will help remove purulent debrisand possibly relieve any blockage. This same can-nulation technique can be used to infuse iodine-based contrast media to confirm the presenceand severity of the blockage and aid in prognosisand long-term management recommendations.

Head TiltHead tilt or torticollis, which is usually an indicationof vestibular dysfunction, can be associated with acentral (e.g., cerebellum, brain stem) or peripheral

Figure 10. Extraction of the incisor teeth is recommended forresolution of persistent malocclusion in rabbits (A). Curved rabbitincisor luxators have been designed to insert into the periodontal

space and help break down the periodontal ligaments (B).

32 Fisher

(e.g., inner ear) neurologic disease process and wasthe most common clinical sign noted in a retrospec-tive study of rabbits with neurologic disease.18 Othervestibular signs include nystagmus and loss of bal-ance and rolling. Causes include bacterial otitis in-terna and infection with Encephalitozoon cuniculi. Adiagnostic and therapeutic plan for head tilt shouldinclude:

● Diagnosis of otitis media/interna is based onclinical signs, aural examination, and imaging,including skull radiography and computed to-mography or magnetic resonance imaging, whenavailable.

● Bacterial culture and sensitivity of deep aural ornasal swabs taken with the rabbit under anesthe-sia are indicated when physical examination sup-ports infection.

● Endoscopic examination performed with therabbit under general anesthesia aids in visualiza-tion of the distal ear canal and tympanic mem-brane.

● Antimicrobial treatment of otitis interna shouldbe long term, 4 to 6 weeks or longer, becauseantibiotics do not penetrate well into pus-filledtympanic bullae. Systemic antibiotics, preferablybased on the results of a bacterial culture andtheir ability to penetrate the central nervous sys-tem, are recommended.

● In addition to antibiotic therapy, affected rabbitsoften benefit from nutritional supplementation,environmental support to minimize the rollingand severe ataxia associated with this disease,and medical therapy with meclizine hydrochlo-ride (Meclizine HCl; Rugby Labs, Duluth, GAUSA) 12.5 to 25 mg/kg by mouth every 12 hours,an antihistamine that aids in the control of asso-ciated dizziness.

● Encephalitozoon cuniculi is a microsporidium, ob-ligate intracellular protozoan parasite. The mostcommonly recognized neurological sign in rab-bits infected with E. cuniculi is vestibular disease.

● Clinical means of diagnosing definitive antemor-tem encephalitozoonosis are limited. However,because E. cuniculi infection is persistent, anti-bodies continue to be produced, and as a gen-

Figure 11. When treating periapical infections and subsequent fa-cial abscessation and osteomyelitis, the author has found the fol-lowing to be the key to long-term resolution: extract all diseasedteeth associated with the abscess, thoroughly debride necrotic andinfected jaw or skull bone (A), marsupialize the abscess capsule tofacial skin, and treat as an open wound (B). It is recommended topack the marsupialized site with gauze strips impregnated withantibiotics, preferably based on bacterial culture, antibiotic sensitiv-ity, and the proclivity of anaerobic bacteria. The packing should bechanged daily and the wound flushed daily or every other day untilhealing, wound granulation, and contracture occur. If the marsupialsite healing is delayed, medicinal-grade honey can be used to packthe area and discourage local infection. One month into the outlined

therapeutic program the abscess is healed (C).

Standards of Care: The Rabbit 33

eral rule the validity of antibody assays for thedetection of E. cuniculi compares favorably withhistology in rabbits.19-21

● In the absence of controlled studies, it is difficultto assess the efficacy of therapeutic agentsagainst E. cuniculi because latent infections occurand some clinical cases may improve spontane-ously without treatment, presumably as a resultof the host’s immune response.22

● Several benzimidazole derivatives, including al-bendazole (30 mg/kg by mouth every 24 hours for30 days),23 oxibendazole (30 mg/kg by mouth ev-ery 24 hours for 7-14 days, then 15 mg/kg by

Figure 12. This 8-year-old female spayed rabbit was presentedwith signs of vestibular disease, including a head tilt and nystagmus(A). There was no evidence of tympanic bulla disease on skullradiography. The rabbit’s E. cuniculi ELISA test was positive and shewas treated with fenbendazole at 20 mg/kg for 30 days. Thevestibular signs resolved with time (B). With encephalitozoonosis,clinical signs may not be associated with the presence of theprotozoa itself, but rather with the inflammatory response thatpersists after the organism has been eliminated.

mouth every 24 hours for 30-60 days),23 and fen-

bendazole (20 mg/kg by mouth every 24 hours for30 days),24 have been used to treat presumptive E.cuniculi infections in rabbits (Fig 12, A and B)based on their antiinflammatory actions and theirin vitro antiprotozoal activity (e.g., bioenergeticdisruptions of membranes and microtubular [tu-bulin] inhibition of E. cuniculi).25-28

Perineal Soiling and DermatitisRabbits often present with matted and soiled peri-neal fur with secondary dermatitis. Causes include

Figure 13. A 6-year-old female spayed rabbit presented with ahistory of progressive rear limb weakness and a recent onset ofperineal soiling. Spinal radiographs (A, B) showed severe thoraciclordosis at T9 to 11 with a distinct concavity in this region on grosspalpation. Spondylosis can contribute to gait abnormalities and theinability to flex the spine to groom the caudal body, resulting in an

unkempt fur coat and perineal soiling.

34 Fisher

inappropriate diet and subsequent soft stools, diar-rhea, and/or urine leakage as a result of infection orexcessive crystalluria (bladder sludge syndrome), en-vironmental factors resulting in behavioral urine re-tention, and decreased ability to groom because ofobesity or pain. A workup should include using casehistory, physical examination findings, and imagingto determine an underlying cause.

● Rule out inappropriate diet and subsequent softstools or diarrhea as a cause.

● Assess patient history: dietary and environmen-tal. Is the rabbit on grass-based hay and pellets?Does the patient get plenty of exercise and op-portunities to urinate? Is the patient obese andunable to groom the perineum?

● Assess for underlying pain by history, physicalexamination, and spinal and joint radiographs;use analgesics when indicated (Fig 13, A and B).

● If you suspect bladder sludge syndrome, informthe client that it is often a disease that can bemanaged but not cured; many rabbits becomesubclinical (Fig 14).

● Bladder sludge syndrome can be ruled out frominfectious cystitis with bacterial culture; a non-contaminated urine sample collected via cysto-centesis is required.

Figure 14. Excessive crystalluria that results in stranguria andpollakiuria with or without perineal soiling requires administration ofsubcutaneous fluids with manual bladder massage/expression aspart of the therapeutic plan. Repeat as necessary until signs aremanaged and bladder function and health (based on clinical signs,physical examination, and imaging) return to normal. Encouragemore water intake by improving access to fresh, clean water andfeeding moistened greens. If nonresponsive to treatment, catheterizethe bladder and flush with warmed 0.9% saline solution with the

rabbit under general anesthesia as shown in this image.

Conclusion

The 21st century is an exciting time to practicerabbit medicine. As one can see, rabbit medicinecontinues to mature and evolve. Nutritional manage-ment, ultrasound imaging, fluid therapy and use ofcolloid fluid products, blood pressure monitoring,preprocedural sedation, and multimodal analgesiaare all considered standards of care for the pet rab-bit. What will the future hold for rabbit medicine?Perhaps more definitive ways to diagnose and treatE. cuniculi infections, more routine use of advancedimaging techniques such as magnetic resonance im-aging, better rabbit-specific pharmacokinetics onmany of the drugs we are presently using, and lastly,new rabbit friendly antibiotics to treat anaerobes andGram-positive bacterial infections. At the rate we aregoing, these advances in rabbit medicine may all bepart of routine standards of care as we approach theyear 2020.

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