To investigate use of a candidate maxillary nerve block in rabbits.
13 healthy New Zealand White rabbits (Oryctolagus cuniculus).
In phase 1, the maxillary nerve block procedure was performed in 7 sedated rabbits with 2 volumes (0.25 and 0.5 mL) of a saline (0.9% NaCl)-tissue marker dye solution (1 injection/side by random assignment). Rabbits were euthanized and dissected; numeric scales were used to rate injection accuracy and extent of staining. In phase 2, the nerve block was performed with articaine hydrochloride-epinephrine solution (0.5 mL) on a randomly assigned side in 6 sedated rabbits, with the contralateral side used as a control. Sensory function of the relevant dermatome was tested in triplicate with an algesiometer 0, 30, and 90 minutes after recovery from sedation. Statistical methods were used to compare results between injection volumes (phase 1) and between treated and control sides (phase 2).
In phase 1, dye was in contact with the targeted nerve after 13 of 14 injections. Accuracy and extent of staining did not differ significantly between volumes. In phase 2, algesiometer-applied force tolerance differed significantly between treated and control sides 30 minutes after recovery from sedation (56 to 145 minutes after the nerve block procedure). No adverse effects were detected in either study phase.
CONCLUSIONS AND CLINICAL RELEVANCE
The described technique for a maxillary nerve block was accurate and effective for desensitization of the relevant dermatome as assessed by algesiometry in healthy rabbits. Additional studies are needed to assess use of this procedure in rabbits of other breeds and its efficacy for clinical use. (Am J Vet Res 2020;81:843-848)
OBJECTIVE To provide contemporary preliminary guidelines for the morphological evaluation of bone marrow in conjunction with CBC results for healthy juvenile (3- to 6-month-old) female New Zealand White rabbits (Oryctolagus cuniculus).
ANIMALS 22 female New Zealand White rabbits.
PROCEDURES Each rabbit was sedated, and a blood sample (3 mL) was collected from an ear artery for a CBC, after which the rabbit was euthanized. Within 5 minutes after euthanasia, bone marrow samples were obtained from the femur for cytologic and histologic evaluation. Bone marrow specimens for cytologic evaluation were stained with modified Wright stain, and those for histologic evaluation were stained with either H&E or Prussian blue stain.
RESULTS The CBC results were within published reference ranges for all rabbits except 4, each of which had mild leukopenia. Cytologic assessment of bone marrow revealed a median myeloid-to-erythroid ratio of 0.7 and 2.8 megakaryocytes/low-power field (magnification, 100X), and the median percentages of lymphocytes, plasma cells, and macrophages were 11.5%, 0.1%, and 0%, respectively. The myeloid-to-erythroid ratio was not significantly correlated with any CBC variable. On histologic evaluation of bone marrow, the cellularity ranged from 30% to 50%, there were 2.1 to 7.7 megakaryocytes/hpf (magnification, 400X), and no iron stores were visible in H&E or Prussian blue–stained specimens.
CONCLUSIONS AND CLINICAL RELEVANCE Results of the present study provided contemporary preliminary guidelines for the evaluation of bone marrow in healthy laboratory rabbits.
Objective—To describe and compare CT abnormalities of the middle ear in rabbits (Oryctolagus cuniculus) that had clinical or subclinical middle ear disease and to determine the prevalence of otitis media and evaluate the role of predisposing factors for otitis media in that species.
Design—Retrospective case series.
Animals—88 domestic rabbits.
Procedures—Medical records for rabbits that underwent CT of the head in June 2007 through February 2014 were searched and classified on the basis of reason for head CT (ie, ear-related disease vs non–ear-related disease). The ears, upper respiratory tract, teeth, and other important structures of each rabbit's head were evaluated. Follow-up information was obtained for rabbits with CT abnormalities of the middle ear without clinical signs (ie, subclinical disease).
Results—12 of 21 (57%) rabbits with clinical signs of ear disease and 18 of 67 (27%) rabbits without clinical signs of ear disease had CT abnormalities of the middle ear. In CT images, all affected ears had soft tissue–attenuating material within the tympanic bulla. Tympanic bulla lysis was associated with clinical middle ear disease. Most (12/18) rabbits with subclinical middle ear disease remained subclinical after CT examination. Middle ear CT-detected changes and lop-ear conformation or otitis externa were strongly correlated; middle ear disease and upper respiratory tract disease were not correlated.
Conclusions and Clinical Relevance—Data suggested that subclinical otitis media frequently affects rabbits, and those with bulla lysis should be closely monitored. Lop-eared rabbits and rabbits with otitis externa had a higher risk of developing otitis media.
Case Description—A 4-year-old castrated male domestic ferret (Mustela putorius furo) was examined because of a 3-week history of intermittent seizures, signs of depression, hypocalcemia, and hyperphosphatemia.
Clinical Findings—Plasma biochemical analysis confirmed hyperphosphatemia (17.7 mg/dL) and low concentrations of total (4.3 mg/dL) and ionized (0.49 mmol/L) calcium. Serum parathyroid hormone concentration (2.30 pmol/L) was low or in the low part of the reference interval.
Treatment and Outcome—Calcium gluconate was administered (2.0 mg/kg/h [0.9 mg/lb/h], IV), followed by a transition to administration of calcium carbonate (53 mg/kg [24.1 mg/lb], PO, q 12 h) and dihydrotachysterol (0.02 mg/kg/d [0.009 mg/lb/d], PO). Attitude of the ferret improved and seizures ceased as blood calcium concentrations increased. The ferret was reexamined because of seizures approximately 1 year after oral maintenance administration of dihydrotachysterol and calcium was initiated. The ferret responded well to emergency and long-term treatment but then was lost to follow-up monitoring. The ferret died approximately 2 years after the initial evaluation and treatment. Hypertrophic cardiomyopathy was diagnosed during necropsy, but the parathyroid glands could not be identified.
Clinical Relevance—To the authors’ knowledge, primary hypoparathyroidism has not previously been reported in a ferret. The condition should be considered for ferrets with hypocalcemia and hyperphosphatemia without azotemia. Treatment with dihydrotachysterol and oral supplementation of calcium appeared to be a viable option for long-term management.
CASE DESCRIPTION A 10-year-old sexually intact male client-owned Texas rat snake (Elaphe obsoleta lindheimeri) was referred for evaluation because of a 5-month history of progressive bilateral ocular opacities and abnormal behavior.
CLINICAL FINDINGS On ophthalmic examination, the snake had bilateral mature cataracts and uveal cysts. No additional ophthalmic or physical abnormalities were detected. Results of CBC, serum biochemical analysis, and ocular ultrasonography were unremarkable.
TREATMENT AND OUTCOME Bilateral spectaculotomy was performed, followed by bilateral phacoemulsification and uveal cyst aspiration, without complication. Histologic evaluation of the phacoemulsified lens material revealed only nonspecific findings associated with cataractogenesis. Vision was restored and the abnormal behaviors resolved after cataract surgery. Long-term follow-up examination performed 60 weeks after surgery revealed no additional ocular or physical abnormalities.
CLINICAL RELEVANCE The ocular anatomic and physiologic characteristics of snakes can pose intraoperative and postoperative challenges to phacoemulsification, but the outcome achieved for this surgical case suggested that successful cataract surgery is possible in these species. This case further demonstrated that cataracts may be associated with reversible behavioral abnormalities in captive snakes.
Case Description—A 5.5-year-old sexually intact female African Grey parrot (Psittacus erithacus) was evaluated for a 1-year history of pronounced polyuria and polydipsia. The bird also had a 1-month history of signs of mild depression and mydriasis.
Clinical Findings—Physical examination revealed a thin body condition and incomplete bilateral mydriasis. Other examination findings as well as CBC and screening radiography results were unremarkable. Plasma biochemical analysis revealed mild hypernatremia. The bird had a 3.3% loss in body weight over 170 minutes during a water deprivation test, and urine osmolality remained low. After IM administration of 0.9 μg of desmopressin, the rate of weight loss decreased substantially and urine osmolality increased 300% over the following 200 minutes.
Treatment and Outcome—Initial attempts to treat the bird with orally administered desmopressin failed to correct the polydipsia and polyuria. Ultimately, IM administration of 24 μg of desmopressin/kg (10.9 μg/lb) every 12 hours yielded a noticeable reduction in water consumption and urine production over a 6- to 8-hour period. Eight months later, the bird was returned for a recheck examination, at which time it was in good health and continued to respond to the medication. Despite continued response to the medication, right-sided internal ophthalmoparesis was detected 16 months after the initial diagnosis.
Clinical Relevance—To the authors' knowledge, central diabetes insipidus in birds has not been reported. The condition should be considered in birds with clinical signs of disease similar to those in mammals. Long-term IM administration of desmopressin may be a viable treatment option.
OBJECTIVE To determine pharmacokinetics after oral administration of single and multiple doses and to assess the safety of zonisamide in Hispaniolan Amazon parrots (Amazona ventralis).
ANIMALS 12 adult Hispaniolan Amazon parrots.
PROCEDURES Zonisamide (30 mg/kg, PO) was administered once to 6 parrots in a single-dose trial. Six months later, a multiple-dose trial was performed in which 8 parrots received zonisamide (20 mg/kg, PO, q 12 h for 10 days) and 4 parrots served as control birds. Safety was assessed through monitoring of body weight, attitude, and urofeces and comparison of those variables and results of CBC and biochemical analyses between control and treatment groups.
RESULTS Mean ± SD maximum plasma concentration of zonisamide for the single- and multiple-dose trials was 21.19 ± 3.42 μg/mL at 4.75 hours and 25.11 ± 1.81 μg/mL at 2.25 hours after administration, respectively. Mean plasma elimination half-life for the single- and multiple-dose trials was 13.34 ± 2.10 hours and 9.76 ± 0.93 hours, respectively. Pharmacokinetic values supported accumulation in the multiple-dose trial. There were no significant differences in body weight, appearance of urofeces, or appetite between treated and control birds. Although treated birds had several significant differences in hematologic and biochemical variables, all variables remained within reference values for this species.
CONCLUSIONS AND CLINICAL RELEVANCE Twice-daily oral administration of zonisamide to Hispaniolan Amazon parrots resulted in plasma concentrations known to be therapeutic in dogs without evidence of adverse effects on body weight, attitude, and urofeces or clinically relevant changes to hematologic and biochemical variables.