ABSTRACT
Use of the chinchilla as a model of middle ear infection in auditory research necessitates accessing the middle ear to collect samples or inoculate bacteria. This column describes a simple technique for middle ear access. The procedure is also useful for investigating and treating middle ear infections in chinchillas.
Subject(s)
Chinchilla/surgery , Ear, Middle/surgery , Animals , Animals, Laboratory , Disease Models, Animal , Otitis Media/pathologyABSTRACT
Thyroid and embedded parathyroid glands were surgically removed (thyroparathyroidectomized) from adult chinchillas (Chinchilla laniger) to create an animal model of hypothyroidism. Thyroxine (T4) levels were measured at the time of surgery and one or two times after surgery from 10 thyroparathyroidectomized chinchillas and five sham controls to establish baseline serum T4 levels and to assess the degree and duration of hypothyroidism in this animal model. Baseline T4 levels ranged from 3.4 to 6.4 microg/dl (mean +/- 1 standard deviation, 5.25 +/- 0.84 microg/dl), with no differences between male and female chinchillas (5.4 +/- 0.6 microg/dl versus 5.2 +/- 1.0 microg/dl, respectively). T4 levels were significantly reduced in 80% of thyroparathyroidectomized chinchillas when measured 6 to 14 days after surgery, but reductions were variable, ranging from 9 to 89% in individual animals. There was rapid regrowth of thyroid tissue and a return of T4 levels to the baseline range in five of the seven animals followed for 1 to 2 months after surgery. T4 levels increased significantly in the sham-operated chinchillas, indicating a nonspecific effect of surgery. The results establish surgical procedures for creating a model of variable, transient hypothyroidism in the chinchilla. We also summarize published basal T4 values for various laboratory animals, to provide a convenient reference.
Subject(s)
Animals, Laboratory/surgery , Chinchilla/surgery , Hypothyroidism , Models, Animal , Parathyroidectomy/methods , Thyroidectomy/methods , Thyroxine/blood , Analysis of Variance , Animals , Animals, Laboratory/blood , Chinchilla/blood , Female , Male , Time FactorsSubject(s)
Cesarean Section/veterinary , Chinchilla/surgery , Dystocia/veterinary , Animals , Dystocia/surgery , Female , PregnancyABSTRACT
Intramuscular injections of ketamine-acepromazine provided satisfactory surgical levels of anaesthesia. Induction was smooth. There was a wide margin of safety with no significant side effects, and there were no deaths attributable to anaesthesia. Induction time was 4-6 min, duration of surgical anaesthesia was 40-60 min, with complete recovery in 2-5 h. 80 chinchillas were used for this study.
Subject(s)
Acepromazine , Anesthesia/veterinary , Chinchilla/physiology , Ketamine , Acepromazine/administration & dosage , Animals , Animals, Laboratory , Chinchilla/surgery , Cochlea/surgery , Electroencephalography/veterinary , Injections, Intramuscular/veterinary , Ketamine/administration & dosageABSTRACT
The chinchilla is of value in otological research for many reasons, including the surgical accessibility of the majority of structures within its temporal bone. This paper describes the anatomy of the chinchilla's temporal bone, and four surgical approaches to the labyrinth and ossicular chain, three through the bulla and the other via the external canal. No one approach reveals all the temporal bone structures, and each route is therefore more suited to some surgical procedures than others. The cochlea is particularly accessible for microsurgical procedures because it projects into the labyrinthine part of the bulla and because its bony capsule is thin. Surgery in the posterior cranial fossae is both hazardous and difficult; the hazard is bleeding from the venous sinuses which run within the occipital and temporal bones, and the difficulty is the limited access due to the intervening cerebellum and the closeness of the brain stem.
