A 9-year-old sexually intact male client-owned Miniature Rex rabbit (Oryctolagus cuniculus; rabbit 1) with a body weight of 1.66 kg (3.65 lb) was referred to the University of Wisconsin-Madison for evaluation of a 3-week history of reduced appetite and right-sided mucopurulent nasal discharge. Initial physical examination revealed right-sided facial swelling at the level of the maxilla and right-sided mucopurulent nasal discharge. The remainder of the physical examination findings were unremarkable, and results of a CBC and serum biochemical analysesa were within reference limits.
The patient was sedated with midazolam (0.5 mg/kg [0.23 mg/lb], IM) and butorphanol (0.5 mg/kg, IM), and CT of the head was performed. Fine-needle aspirates of the maxillary mass were obtained. Review of CT images revealed a well-circumscribed, soft tissue–attenuating, subcutaneous mass located at the rostrolateral aspect of the right maxilla (Figure 1). Additionally, soft tissue–attenuating material with central amorphous mineralization was evident in the right nasal cavity and ipsilateral maxillary sinus. The nasal turbinates were absent in the areas of soft tissue attenuation.
Cytologic examination of fine needle aspirates revealed evidence of septic heterophilic inflammation, with heterophils admixed with granular debris, and intracellular and extracellular cocci. These findings were consistent with a diagnosis of severe right-sided rhinosinusitis with lateral extension to the subcutaneous tissues overlying the maxilla. The patient was admitted to the hospital, and lateral rhinostomy for exploration and debridement of the right nasal cavity was scheduled for the following day.
The rabbit was sedated with butorphanol (0.5 mg/kg, IM), midazolam (0.5 mg/kg, IM), and ketamine (10 mg/kg [4.5 mg/lb], IM). A 26-gauge, 1.9-cm-long catheter was placed in the left lateral ear vein, and a balanced electrolyte solution was administered at a rate of 5 mL/kg/h (2.3 mL/lb/h) IV, throughout the procedure. After an appropriate level of sedation was achieved, the patient was preoxygenated for 5 minutes with administration of 100% oxygen by means of a tight-fitting face mask, and then general anesthesia was induced with administration of isoflurane in oxygen via mask. A 3-mm-diameter uncuffed endotracheal tube was placed, and anesthesia was maintained with delivery of isoflurane (1.5% to 2.5%) in oxygen for the duration of surgery. Indirect blood pressure (measured with Doppler oscillometry), heart rate and rhythm (lead II ECG), arterial oxygen saturation (measured with pulse oximetry), and end-tidal carbon dioxide concentration (measured with capnography) were monitored throughout the procedure. The rabbit was positioned in left lateral recumbency with the head lower than the body to facilitate nasal drainage and decreased the possibility of aspiration. After standard skin preparation and draping for surgery, a 1.5-cm-long craniocaudal skin incision was made over the facial swelling. Blunt and sharp dissection through the subcutaneous tissues and musculature, with care to preserve nerves and vasculature, were performed to explore the swelling. The swelling was incised, and a large volume of purulent material was removed. The surgical site was then carefully lavaged with warm sterile saline (0.9% NaCl) solution. The residual cavity was then explored with a rigid endoscopeb for gross evidence of infection (ie, residual purulent material) and for evidence of a communication with the nasal cavity or paranasal sinuses. At the dorsal aspect of the mass, at the level of the facies cribrosa of the maxillary bone, a small communication with the right maxillary sinus was identified and enlarged by means of insertion of blunt hemostatic forceps to allow access to the right nasal cavity via the maxillary sinus (Figure 1). Additional purulent material located in the right nasal meatus and the right maxillary sinus was then removed with a combination of lavage and suction with endoscopic guidance. Several fragments of abnormal-appearing mineralized material were present in the nasal cavity and were retrieved for subsequent histologic examination and aerobic and anaerobic microbial culture.
After endoscopic exploration and debridement of the affected area, marsupialization of the surgical site was performed by suturing the facial skin to the opening of the nasal cavity with 4-0 nylon suture in a simple interrupted suture pattern. A sustained-release antimicrobial gelc was then instilled in the wound (Figure 1). The rabbit recovered from anesthesia without complications. Meloxicam (0.5 mg/kg, SC) was administered just prior to extubation to reduce inflammation and provide analgesia. Histologic examination of tissue samples obtained during surgery identified the mineralized material as nasal bone surrounded by pockets of heterophilic inflammation with evidence of bony remodeling. Moderate growth of an α-hemolytic Streptococcus strain was identified on microbial culture of specimens collected from the maxillary sinus; however, the isolate could not be grown for antimicrobial susceptibility testing.
The patient was eating well by the evening of surgery and was discharged the next day with instructions to follow up with the referring veterinarian. Medications dispensed at discharge included meloxicam (0.3 mg/kg [0.14 mg/lb], PO, q 12 h for 7 days), gentamicin ophthalmic solution (1 drop topically in the right eye and 1 drop topically at the surgical site, q 12 h for 14 days), enrofloxacin (10 mg/kg, PO, q 12 h for 21 days), and penicillin G procaine–penicillin G benzathine (50,000 U/kg [22,727 U/lb], SC, q 5 d for 3 doses). At a follow-up visit 1 month after surgery, the referring veterinarian removed the sutures and reported that the ostium had apparently healed by means of second intention, with patent nares bilaterally. The owners reported that the rabbit had apparently normal behavior and appetite.
The rabbit was reexamined at the University of Wisconsin-Madison 13 months later for evaluation of an odontogenic abscess of the left mandible. Computed tomography of the head was repeated (Figure 1). There was no evidence of the previously noted soft tissue– attenuating mass adjacent to the right maxilla, and signs of right-sided rhinitis had resolved. However, there was persistent irregularity and thinning of the rostrolateral aspect of the right maxilla and absence of nasal turbinate anatomy in some areas of the right nasal cavity when compared with the left.
A 10-year-old sexually intact male client-owned Miniature Rex rabbit (rabbit 2) weighing 1.85 kg (4.07 lb) was evaluated because of a 4-year history of intermittent signs of upper respiratory tract disease. Clinical signs of upper respiratory tract disease included intermittent right-sided oculonasal discharge, recurrent right dacryocystitis, and persistent sneezing. The rabbit had been treated with repeated lavage of the right nasolacrimal duct, nebulization with warmed saline solution, gentamicin ophthalmic drops (2 drops, topically in the right eye, q 8 h), trimethoprim sulfomethoxazole (30 mg/kg [13.6 mg/lb], PO, q 12 h), and meloxicam (0.5 mg/kg, PO, q 24 h). Microbial culture of a sample of the purulent nasal discharge performed 5 months prior to examination produced heavy growth of Pseudomonas aeruginosa, susceptible to a large number of antimicrobials. The owners had previously repeatedly declined further diagnostic evaluation including CT because of financial constraints.
On evaluation, the patient had a lack of air flow through the right nostril, a right-sided oculonasal discharge and a palpable swelling between the right eye and right nostril. The rabbit was sedated for CT of the head, which revealed findings consistent with right-sided chronic rhinitis, maxillary sinusitis, and bony lysis (Figure 2). A large, mildly heterogeneous, fluid-attenuating mass with several soft tissue–attenuating foci was evident in the right nasal cavity, extending to the right maxillary sinus and involving the rostral aspect of the nasal cavity to the level of the palatine bone. The mass completely occluded the right nasal cavity, with associated deviation of the nasal septum to the left and an apparent septal defect rostroventrally. Because of the extent of the lesion, surgical exploration and debridement by means of lateral rhinostomy were elected.
The patient was premedicated with midazolam (0.5 mg/kg, IM), butorphanol (0.5 mg/kg, IM), and ketamine (5 mg/kg [2.3 mg/lb], IM), and general anesthesia was induced and maintained as described for rabbit 1. Surgical exploration, debridement, and lavage were also performed as described. Tissue samples were obtained for microbial culture and susceptibility testing. Heavy growth of a Pasteurella sp and Streptococcus intermedius, both susceptible to a large number of antimicrobials (including fluoroquinolones) on susceptibility testing, was obtained. The patient recovered from anesthesia without complications and was active and eating the same day. The animal was discharged the day after surgery, with meloxicam (0.5 mg/kg, PO, q 24 h for 7 days), enrofloxacin (10 mg/kg, PO, q 24 h for 28 days), and gentamicin 0.3% ophthalmic drops (1 or 2 drops topically to the right eye, q 4 to 6 h for 14 days). The rabbit was reexamined 3 days later. The rhinostomy site was covered with a scab, and a small amount of purulent material had accumulated. The area was cleaned, and the surgical site was lavaged to remove the purulent material. Three additional visits over a 1-month period included similar treatments. At the third visit (20 days after surgery), the ostium had healed, with visible granulation tissue (Figure 3); both nares were patent and the owner reported no recurrence of upper respiratory signs. The rabbit was evaluated again 5 months after surgery because of a mild recurrence of sneezing. Computed tomography of the head was repeated, revealing persistent enlargement of the right nasal cavity but nearly complete resolution of signs of rhinosinusitis. A small amount of fluid was evident in the right nasal passage, consistent with a diagnosis of mild chronic rhinitis.
VetScan Comprehensive Diagnostic Profile, Abaxis Inc, Union City, Calif.
Hopkins II telescope (30°, 2.7 mm, 18 cm; 64019BA), Karl Storz Veterinary Endoscopy America Inc, Goleta, Calif.
Silvasorb Gel, Medline Industries Inc, Mundelein, Ill.
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