A 1-year-old sexually intact female Netherland dwarf rabbit (Oryctolagus cuniculus) with a 3-week history of signs of lethargy, decreased appetite, left unilateral exophthalmia, a resolved draining sinus from a left maxillary facial abscess, and bilateral nasal discharge was referred to the Exotic Animal, Wildlife, and Zoological Medicine Service at the University of Georgia Veterinary Teaching Hospital. Prior to referral, the rabbit had undergone surgery for an abscess involving the left maxillary area of the face and had been treated with several antimicrobials, including enrofloxacin, trimethoprim-sulfonamide, and cephalexin (dosages unknown).
At the time of initial examination at the teaching hospital, the rabbit weighed 1.0 kg (2.2 lb) and was in poor body condition (body condition score, 1.5/5). Generalized muscle atrophy and bilateral mucopurulent nasal discharge with severe exophthalmia of the left globe were observed. The frequency of gastrointestinal sounds was abnormally low in all 4 abdominal quadrants, but findings pertinent to the cardiorespiratory system were considered normal.
Initial diagnostic tests included hematologic and plasma biochemical analyses, measurement of the serum Pasteurella multocida antibody titer,a cranial and thoracic radiography, ophthalmologic examination, and ultrasonographic examination of the globe and retrobulbar space in both eyes. The rabbit was anesthetized to facilitate radiographic imaging, ophthalmic ultrasonography, and detailed oral cavity examination. Sevoflurane (7%) in oxygen was delivered by means of a face mask in a Norman elbow nonrebreathing systemb to induce anesthesia, and 2% to 3% isoflurane was administered for anesthetic maintenance. A blood sample (2.5 mL) was collected from the central auricular artery. Hematologic analysis revealed normochromic macrocytic anemia with moderate anisocytosis and severe polychromasia: Hct was 25% (reference range, 30% to 50%), RBC count was 3.33 × 106 RBCs/μL (reference range, 4 to 8 × 106 RBCs/μL), hemoglobin concentration was 8.1 g/dL (reference range, 8.0 to 17.5 g/dL), mean corpuscular volume was 75 fL (reference range, 58.0 to 66.5 fL), and mean corpuscular hemoglobin concentration was 32.4 g/dL (reference range, 29 to 37 g/dL).1,2 The WBC count was slightly high at 12.7 × 103 leukocytes/μL (reference range, 5 to 12 × 103 leukocytes/μL), and apart from mild neutrophilia (61%; reference range, 33% to 55%), the leukocyte differential was within reference range.1,2 Results of plasma biochemical analyses were within reference ranges, and there was no serum anti–P multocida antibody titer.
Radiographs of the cranium (dorsoventral, right and left lateral, and oblique views) were obtained on a mammography cassettec and films.d Radiography revealed severe malocclusion of the premolars and molars, with multiple elongated roots. The left maxillary second molar appeared to penetrate into the left retrobulbar space. These findings were consistent with severe dental disease3 (Figure 1). Ophthalmic examination confirmed exophthalmia and a dorsally deviated left globe that could not be retropulsed. Intraocular pressuree was 14 and 13 mm Hg in the right and left eye, respectively. Fluorescein stainingf revealed a superficial corneal ulcer in the left eye. Ocular ultrasonography revealed a poorly defined area of hypoechoic, flocculent-appearing material caudomedial to the left globe, most consistent with a retrobulbar abscess (Figure 2).
The rabbit was hospitalized for supportive care overnight and was scheduled for elective surgery for tooth removal and abscess debridement the following day. Fifteen minutes before anesthetic induction via a face mask, the rabbit was premedicated with midazolam (0.5 mg/ kg [0.23 mg/lb], IM), hydromorphone (0.1 mg/kg [0.05 mg/lb], IM), and glycopyrrolate (0.01 mg [0.005 mg/lb], IM). After induction, the rabbit was intubated by use of a fiberoptic laryngoscopeg and a 2-mm uncuffed nasotracheal tube.h A 24-gauge IV catheter was placed in the cephalic vein, and 22.2 mL of half-strength lactated Ringer's solution (NaCl concentration, 0.45%) containing 2.5% dextrose was administered at 10 mL/h during the anesthetic period. The rabbit was positioned in sternal recumbency on a towel over a warming blanket.i The rabbit's head was placed over the dentistry board with the mouth elevated and held open with a dental head support.j Anesthesia was monitored with a capnographk and indirect blood pressure determination.l The pharynx was packed with moistened gauze.
Endoscopic examination was performed with a 5-mm, 0° otoendoscope and a 2.7-mm, 30° Hopkins telescope attached to a xenon light source via a fiber-optic cable and a camera providing video feed to a monitor.4,m Digital video and still images were captured with a documentation system. Stomatoscopy revealed minor elongation of and a lingual spur associated with the left mandibular fourth premolar, which was reduced by use of a rotary power tooln and a dental burr.° The left maxillary second molar was found to be loose, and exudate emanated from the gingival margin around it (Figure 3). A small angled elevator was used to break down the soft tissue attachments securing the molar.
Small hemostats were used to grasp the crown and rotate the molar around its longitudinal axis before elevating the tooth, in its entirety, into the oral cavity. A swab was inserted into the socket, and a swab specimen was submitted for aerobic and anerobic bacterial culture. A second swab was used to obtain smears for Gram staining and cytologic analysis. A mixed population with gram-positive and gram-negative bacilli and many degenerative polymorphonuclear cells was detected, consistent with bacterial infection.
With endoscopic guidance, an angled curette was used to debride and remove inspissated material from the socket in piecemeal fashion (Figure 3). Gentle retropulsion of the left eye was used to aid in removal of inspissated material. An 18-gauge catheter was directed into the cavity, which was copiously flushed with 200 mL of warm sterile saline (0.9% NaCl) solution. Endoscopic examination yielded visual confirmation of a cavity, and maxillary and dental elements were visible through the gingival defect. The cavity was flushed with 3.0 mL of sterile saline solution containing 300 mg of gentamicin and 100 mg of doxycycline. Meloxicam (0.5 mg, SC) was given for postoperative pain control. Anesthesia was discontinued, and the rabbit recovered from anesthesia without complications.
The rabbit was discharged from the hospital with instructions to the owners to administer a triple antimicrobial ophthalmic ointment (containing bacitracin, neomycin, and polymixin B sulfate and administered topically, every 8 hours, for 10 days), penicillin G (60,000 U/kg [27,300 U/lb], SC, q 48 h, for 21 days),5,6 and meloxicam (0.5 mg/kg, PO, q 12 h, for 10 days). One week after surgery, results of bacterial culture of the abscess fluid revealed light growth of Pseudomonas aeruginosa and very light growth of Enterococcus spp. No anaerobic organisms were isolated. Results of susceptibility testing revealed that no single antimicrobial was effective against both bacteria. Therefore, ciprofloxacin (10 mg/kg [4.5 mg/lb], PO, q 12 h) was added to the treatment regimen at the time of the first recheck (2 weeks after surgery), and treatment was continued for 21 days.
The rabbit was reevaluated 2, 3, and 4 weeks after surgery. During those examinations, improvements in demeanor and appetite were observed, along with a 14% weight gain to 1.14 kg (2.5 lb) at the time of the first reevaluation. The corneal ulcer and nasal discharge had completely resolved 3 weeks after surgery. There was a gradual decrease in the degree of exophthalmia, and repeat cranial radiographs (16 days after initial radiographs) revealed the absence of the left maxillary second molar and the results of trimming of occlusal surfaces of the remaining molar teeth (Figure 4). Stomatoscopy revealed a caseous plug at the site of the left maxillary second molar extraction; the site was debrided with an angled curette. The cavity had decreased in size and was copiously flushed with sterile saline solution and antimicrobials, as described. The course of antimicrobial treatment was consequently extended until complete clinical remission was observed. Ocular ultrasonography performed 4 weeks after the initial surgery revealed no flocculent material or other evidence of an abscess (Figure 2). Given the absence of obvious signs of retrobulbar infection and the tendency for food and debris to accumulate in the cavity, an antimicrobial-impregnated bioactive dental ceramicp was used to fill the defect. Doxycycline (50 mg) was mixed with 2.5 mL of reconstituted dental ceramic and infused into the cavity.
Two months after the initial surgery, only minimal exophthalmia was evident and no further physical, radiographic, or ultrasonographic changes were noticed. Stomatoscopy examination revealed no opening or cavity. Results of blood testing were within reference ranges. Administration of ciprofloxacin and penicillin G was discontinued at that time. Physical and ophthalmic examinations 6 months after the surgery yielded no remarkable findings, and the rabbit weighed 1.4 kg (3.1 lb) and had a body condition score of 3/5. Stomatoscopy confirmed overgrowth of the left mandibular second molar, and small spurs affecting the lingual surface of the left maxillary second and third premolars were reduced. The owner was advised to monitor the rabbit's weight and have dental examinations repeated every 6 months. One year after the initial diagnosis, the rabbit was clinically normal and no further complications were reported.
Infectious Diseases Laboratory, University of Georgia, College of Veterinary Medicine, Athens, Ga.
Bickford PC-2B, Bickford Inc, Wales Center, NY.
Mamoray cassette, Mamoray HDS, AGFA Corp, Greenville, SC.
Mamoray film, Mamoray HDR-C film, AGFA Corp, Greenville, SC.
Mentor, Norwell, Mass.
Chauvin Pharmaceuticals Ltd, Harold Hill, Romford, Essex, UK.
5197-100 SITElite handle and clarus SITEcoupler model 30100 (pediatric) eyepiece, Clarus Medical LLC, Minneapolis, Minn.
Rusch Inc, Duluth, Ga.
T/pump system of TP22 pad and TP500 pump, Gaymar Industries Inc, Orchard Park, NY.
Rabbit/rodent dental head support, Sontec Instruments Inc, Englewood, Colo.
Ohmeda 5250 respiratory gas monitor, BOC group, Louisville, Colo.
Tycos Hand Aneroid Sphygmomanometer, Miami Medical, Glen Allen, Va.
Karl Storz Veterinary Endoscopy America Inc, Goleta, Calif.
Dremel Multipro model 395, Robert Bosh Tool Corp, Dremel Service Center, Racine, Wisc.
3-mm round long burr, Surgical Innovations Inc, Suwanee, Ga.
Consil, Nutramax Laboratories Inc, Edgewood, Md.
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