Contemporary topics in laboratory animal science / American Association for Laboratory Animal Science
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Contemp Top Lab Anim Sci · Nov 2005
Comparative StudyLack of correlation of vaginal impedance measurements with hormone levels in the rat.
Hormone levels vary in female rats depending on estrous cycle stage. Vaginal cytology is a reliable method of staging female rats, but vaginal impedance offers an alternative depending on application. We sought to correlate vaginal impedance in cycling female rats with hormone levels. ⋯ No correlation occurred between vaginal impedance and hormone levels in unstaged rats (n = 41). Two animals evaluated for reproductive tract histology showed evidence of pseudopregnancy. Vaginal impedance may be useful in distinguishing estrus from nonestrus rats but may be limited for chronic estrous cycle monitoring because of the possible risk of inducing pseudopregnancy.
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Contemp Top Lab Anim Sci · Sep 2005
Comparative StudyComparison of tympanic, transponder, and noncontact infrared laser thermometry with rectal thermometry in strain 13 guinea pigs (Cavia porcellus).
The purpose of this experiment was to assess the practicality, ease, and reliability of using tympanic, transponder, and noncontact infrared laser thermometry versus rectal thermometry in strain 13 guinea pigs. Body temperatures were measured by all four methods within each animal over 10 min, and three sets of measurements were taken over 2 days. Each method was compared for agreement over time and agreement with the rectal temperature of each animal. ⋯ Although the mean temperatures from the transponder and tympanic thermometers were not significantly different from the rectal temperatures, only the transponder method was in close agreement with the rectal method. The tympanic and noncontact infrared laser methods had poor agreement with the rectal method. These study results suggest that transponder thermometry is an easy and accurate alternative to rectal thermometry in strain 13 guinea pigs.
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Contemp Top Lab Anim Sci · Sep 2005
Comparative StudyA comparison of target-controlled infusion versus volatile inhalant anesthesia for heart rate, respiratory rate, and recovery time in a rat model.
We conducted this study to determine whether heart rate, respiratory rate, and recovery time differed significantly between rats receiving target-controlled infusion (TCI) and those under volatile inhalant anesthesia. TCI rats received intravenous propofol at an average effect site concentration of 11.3 microg/ml or propofol plus ketamine (5 mg/ml of propofol) at an average effect site concentration of 8.7 microg/ml. Inhalant anesthesia rats received isoflurane (average, 1.8%) delivered in medical-grade air. ⋯ Recovery time was longer for both TCI regimens compared with isoflurane (P <0.001). Once venous access was accomplished, TCI anesthesia with propofol or propofol combined with a low dose of ketamine was comparable to an isoflurane inhalant regimen in ease of administration and control of the anesthetic event when used in rats for procedures of 1-h duration. Respiratory rate was increased and recovery time was longer for rats receiving the TCI regimens.
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Contemp Top Lab Anim Sci · Mar 2005
Comparative StudyA simple device for humidification of inspired gases during volatile anesthesia in rats.
The typical setup for administering volatile anesthetics to laboratory rats does not provide for humidification of the inspired gases, although it is known that failing to provide humidification can lead to airway inflammation and impaired pulmonary function during prolonged experimental protocols. We developed a simple humidification system in which a nebulizer was inserted into the nonrebreathing circuit used with a standard isoflurane vaporizer. We show here that the nebulizer system resulted in anesthetic stability, as measured by withdrawal reflex latency. Although the isoflurane concentration in the delivered gases was reduced, the reduction was a consistent percentage of the vaporizer output throughout the anesthetic range, thereby permitting straightforward adjustment of the vaporizer output.
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Contemp Top Lab Anim Sci · Jul 2004
Comparative StudyEndotracheal tubes versus laryngeal mask airways in rabbit inhalation anesthesia: ease of use and waste gas emissions.
In this study, we compared two endotracheal tubes (cuffed [Murphy Eye type] and uncuffed [Cole type]) and a pediatric laryngeal mask airway (LMA) with respect to their ease of use in rabbits and their capacities to limit waste isoflurane emissions. Animals (New Zealand White, 3.3 to 5.0 kg, n = 8) were sedated with intramuscular ketamine (50 mg/kg) and xylazine (10 mg/kg). After 5 min, the larynx was numbed with cetocaine, an intubation device was positioned, and anesthesia was maintained with isoflurane (2%) in oxygen (1 liter/min). ⋯ Isoflurane was not detected in the operator's breathing zone. These data show that the uncuffed endotracheal tube (usually used to anesthetize birds and reptiles) and the pediatric LMA can be used in rabbits as readily as a cuffed tube. In addition, our findings indicate that tradeoffs will be required in selecting a delivery system for this species, as the easiest apparatus (the LMA) also emits the most isoflurane waste.