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Biomedical subjects

T A Tobias

Publications and source records attributed to T A Tobias.

6 recordsLinked to original sources
PubMed1998

Determination of age in dogs and cats by use of changes in lens reflections and transparency.

OBJECTIVE: To develop and test a noninvasive technique for determining age in dogs and cats on the basis of changes in lens reflections and transparency. ANIMALS: 85 dogs representing 5 breeds and 73 domestic shorthair cats. PROCEDURE: While examining dilated eyes in a darkened room, using a penlight, 2 experienced examiners who were blinded to actual age of animals individually measured the diameter of reflections from the anterior (La) and posterior (Lb) surfaces of the lens and scored lens transparency (Ltr) from 1 (clear) to 5 (severe opacity). Models were developed to predict age on the basis of these measurements. RESULTS: Aging models developed for dogs and cats were as follows: Age(dogs) = 2.197 - 0.070 x (La) + 1.361 x (Lb) + 1.193 x (Ltr) and Age(cats) = 1.988 + 1.024 x (La) + 2.220 x (Lb) + 1.019 x (Ltr), where age was expressed in years, and La and Lb were in millimeters. All variables, except La in dogs, contributed significantly to accuracy of the models. Correlation between predicted and actual ages, as measured by Pearson's product-moment correlation coefficient, was significant in both species (P < 0.0001). Significant differences were not found between examiners or between the first and second evaluations by the same examiner. CONCLUSIONS AND CLINICAL RELEVANCE: A noninvasive technique based on evaluation of lens reflections and transparency can provide clinically useful predictions of age in mature dogs and cats. This technique could be an important tool for veterinarians or humane shelters in determining differential diagnoses and assessing longevity and adoptability of mature animals of unknown age.

Aging↗
PubMed1994

Comparative effects of 7% NaCl in 6% dextran 70 and 0.9% NaCl on oxygen transport in endotoxemic dogs.

We compared the effects of 7% NaCl in 6% dextran 70 (HSD) and 0.9% NaCl (IS) resuscitation of endotoxic dogs on hemodynamic and cardiorespiratory parameters and the oxygen consumption-delivery relationship. Escherichia coli endotoxin (3 mg.kg-1, intravenously) was infused over 5 min into 13 paralyzed, chloralose-anesthetized, splenectomized dogs. Six additional dogs received a sham endotoxin infusion (saline) and served as controls. After 30 min, the endotoxic animals were resuscitated to 150% of their baseline cardiac output (CO) and maintained at this CO for 30 min using 7% NaCl in 6% dextran 70 (HSD at 1 ml.kg-1.min-1; n = 7) or 0.9% NaCl (IS at 4 ml.kg-1.min-1; n = 6). Oxygen consumption (VO2), measured by indirect calorimetry, hemodynamic parameters, and oxygen delivery (DO2), improved in similar temporal patterns in both groups during resuscitation and VO2 reached steady-state values. Oxygen delivery, VO2, mean arterial pressure, and cardiac output did not significantly differ between groups at the end of resuscitation, but VO2 increased significantly from baseline values only in the HSD group. The total volume of HSD administered averaged 10.0 +/- 0.2 ml.kg-1 which was significantly less than the volume of IS, which averaged 67.2 +/- 9.3 ml.kg-1. Incremental hemorrhages (2-5 ml.kg-1) were then performed in all dogs to determine the oxygen consumption-delivery relationship and the critical level of oxygen delivery (DO2Crit). The average DO2Crit values of the HSD, IS, and control groups were 9.42, 9.15, and 6.82 ml.min-1.kg-1, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Vagal innervation influences the whole body oxygen consumption-delivery relationship in the dog.

Vagotomy alters regional blood flow distribution by interrupting the tonic central inhibitory effect of cardiopulmonary vagal afferent nerves on sympathetic outflow predominantly to the renal, splanchnic, and cutaneous circulations. We hypothesized that the alteration of blood flow distribution by vagotomy would lead to disruption of the oxygen consumption-oxygen delivery relationship (VO2/DO2), increase critical DO2 (DO2Crit), and decrease whole-body oxygen extraction ratio (O2ER). Nineteen chloralose-anesthetized, paralyzed, splenectomized dogs were submitted to either bilateral vagosympathectomy (n = 7), bilateral vagotomy (n = 6), or sham denervation (n = 6) following baseline cardiorespiratory parameter measurement. VO2 was measured by indirect calorimetry and carotid blood flow by ultrasonic flow probe. Incremental hemorrhages (1-5 mL/kg) were performed to determine the VO2/DO2 relationship. Cardiorespiratory parameters were measured after each hemorrhage at steady-state VO2. DO2Crit was derived from the VO2/DO2 relationship using a best-fit regression analysis technique. The average DO2Crit values of the vagotomy (9.1 +/- .54) and vagosympathectomy (11.5 +/- 1.2 mL/min/kg) groups were significantly greater than the control group (7.72 +/- .43). After hemorrhage had been performed to a point that decreased mean arterial pressure to approximately 70 mmHg from baseline values, carotid blood flow in the vagosympathectomy group was significantly greater than the control group. We conclude that vagotomy disrupts the VO2/DO2 relationship. Vagosympathectomy causes a severe disruption of the VO2/DO2 relationship, probably by the combined effect of vagotomy and interruption of sympathetic nervous system control of blood flow to the head and neck.

Animals↗
PubMed1993

Comparative effects of 7.5% NaCl in 6% Dextran 70 and 0.9% NaCl on cardiorespiratory parameters after cardiac output-controlled resuscitation from canine hemorrhagic shock.

We resuscitated severely hemorrhaged (mean arterial pressure at 40 mm Hg for 30 min) pentobarbital-anesthetized dogs to 120% of control cardiac output with 7.5% NaCl in 6% Dextran 70 (HSD) or 0.9% NaCl (IS) to compare the effects on hemodynamic and oxygen transport parameters. Hemodynamic parameters and oxygen delivery did not differ between groups. Oxygen consumption and oxygen extraction ratio tended to be higher, and mixed venous oxygen tension lower (P < 0.05) for HSD during the first hour of the postresuscitation period. Resuscitation of the HSD group required significantly less time (10.4 +/- 2.0 vs. 23.6 +/- 1.7 min; P < 0.01) and fluid volume (8.0 +/- 1.1 vs. 47.0 +/- 3.3 ml.kg-1; P < 0.01). We conclude that the resuscitation of hypovolemic dogs with HSD and IS to equivalent cardiac output results in identical improvements in hemodynamics and oxygen delivery but that HSD may provide a better oxygen supply/demand balance during the first hour postresuscitation.

Animals↗
PubMedDate not supplied

Comparison of intra-articular and epidural morphine for analgesia following stifle arthrotomy in dogs.

We prospectively studied 18 dogs that presented for exploratory stifle arthrotomy, with or without meniscectomy, and lateral extracapsular stabilization as a result of cranial cruciate ligament rupture. Dogs were premedicated with acepromazine, induced with thiopental, and maintained with halothane in oxygen. Preoperatively, dogs were assigned to one of three groups. Group 1 (n = 6) received intra-articular morphine (0.1 mg/kg diluted in 1 mL/10 kg body weight of saline) and epidural saline (1 mL/5 kg body weight saline plus the volume of saline representing 0.1 mg/kg of morphine). Group 2 (n = 6) received intra-articular saline (1 mL/10 kg body weight of saline plus the volume of saline representing 0.1 mg/kg of morphine) and epidural saline (1 mL/5 kg body weight saline plus the volume of saline representing 0.1 mg/kg of morphine). Group 3 (n = 6) received intra-articular saline (1 mL/10 kg body weight of saline plus the volume of saline representing 0.1 mg/kg of morphine) and epidural morphine (0.1 mg/kg of morphine diluted in 1 mL/5 kg body weight saline). The efficacy of each analgesia regimen was evaluated for 6 hours postoperatively with a pain score based on subjective and objective variables. Serum cortisol and blood glucose concentrations were measured. Butorphanol was used to provide analgesia as needed based on a predetermined maximum pain score. Supplemental analgesics were required postoperatively every 2 to 3 hours for 6 hours in all dogs that did not initially receive analgesics (group 2). Pain scores were significantly lower in dogs administered morphine intra-articularly (group 1) and epidurally (group 3) at 30 minutes and 30, 120, and 360 minutes, respectively, compared with dogs that did not initially receive analgesics (group 2). One dog in group 1 and one dog in group 3 required supplemental analgesia with butorphanol. There was no difference between analgesia produced by intra-articular morphine compared with that of epidural morphine. Side effects after intra-articular or epidural morphine were not observed. Intra-articular administration of morphine can produce effective analgesia in dogs comparable with that produced by epidural administration of morphine.

Analgesia↗