Effects of medetomidine and midazolam alone or in combination on the metabolic and neurohormonal responses in healthy cats

The purpose of this study was to investigate the effects of a medetomidine-midazolam combination on some neurohormonal and metabolic variables in healthy cats. Five cats were used repeatedly in each of 5 groups, which were injected intramuscularly with physiological saline solution (control), 0.5 mg/kg of midazolam, 40 microg/kg of medetomidine, 80 microg/kg of medetomidine, and 40 microg/kg of medetomidine plus 0.5 mg/kg of midazolam. Blood samples were taken 10 times over 24 h from a catheter introduced into the jugular vein. Plasma concentrations of glucose, insulin, glucagon, cortisol, nonesterified fatty acids (NEFAs), norepinephrine, and epinephrine were determined. In addition, the duration of lateral recumbency, rectal temperature, heart rate, and respiratory rate were examined. The combination of medetomidine and midazolam enhanced the duration of lateral recumbency and reduced the hyperglycemia induced by medetomidine alone. Recovery from hypoinsulinemia induced by the medetomidine-midazolam combination tended to be more rapid than when the same dose of medetomidine was used alone. The decrease in plasma norepinephrine levels induced by medetomidine alone was diminished by the addition of midazolam. Midazolam alone did not significantly change the plasma glucose, insulin, glucagon, cortisol, epinephrine, or NEFA concentration, but increased the norepinephrine concentration. This study revealed that the combination of medetomidine and midazolam produces minimal neurohormonal and metabolic changes when compared with medetomidine alone in cats.     

Neurohormonal and metabolic effects of medetomidine compared with xylazine in healthy cats

The purpose of this study was to investigate and compare the effects of medetomidine and xylazine on some neurohormonal and metabolic variables in healthy cats. Five cats were used repeatedly in each of 11 groups, which were injected intramuscularly with physiological saline solution (control), 20, 40, 80, 160, and 320 microg/kg of medetomidine, and 0.5, 1, 2, 4, and 8 mg/kg of xylazine. Blood samples were taken over 24 h from the jugular vein for determination of plasma glucose, insulin, cortisol, epinephrine, norepinephrine, glucagon, and nonesterified fatty acid concentrations. Both medetomidine and xylazine induced remarkable hyperglycemia that was dose-dependent except for the response to medetomidine from 0 to 3 h. Both agents suppressed epinephrine and norepinephrine release but not in a dose-dependent manner at the tested dosages. Both agents inhibited insulin release and lipolysis, with similar potency, and tended to suppress cortisol release. The glucagon levels did not change significantly in any of the groups. These results suggest that the effects of medetomidine and xylazine on glucose metabolism and catecholamine release may not be due only to the actions mediated by alpha2-adrenoceptors.     

Effect of specimen collection and storage on blood glucose and lactate concentrations in healthy,hyperthyroid and diabetic cats

Abstract: The objective of this study was to compare and investigate differences in glucose and lactate concentrations in sodium fluoride/potassium oxalate (NaF/Ox) plasma and serum in healthy cats and cats with metabolic disease. Glucose and lactate concentrations were determined in routinely processed serum and NaF/Ox plasma obtained from healthy (n = 30), hyperthyroid (n = 27) and diabetic (n = 30) cats, and in samples from 6 healthy cats stored at 25°C or 4°C for 0,1, 2, 4, or 8 hours. The packed cell volume (PCV) of blood collected in NaF/Ox was compared with that of blood collected in EDTA. Mean glucose concentration was significantly (P < .05) lower in NaF/Ox plasma than in serum in all groups of cats, by 0.7–2.5 mmol/L (11–45 mg/dL); the difference was greater in cats with hyperglycemia. Mean lactate concentration was significantly higher in serum than in NaF/Ox plasma in all groups of cats, by 0.4–1.2 mmol/L (3.6–10.8 mg/dL); the difference was greater in hyperthyroid and diabetic cats. In vitro, only serum stored on the clot for ≥ 1hour at 25°C had significantly lower glucose and higher lactate concentrations. The PCV of NaF/Ox-anticoagulated blood was lower than that of EDTA-anticoagulated blood, by 7.0%± 1.4% (P<.01). In conclusion, collection of feline blood in NaF/Ox was necessary to prevent in vitro increases in lactate concentration; however, NaF/Ox artifactually decreased plasma glucose concentration because of RBC shrinkage. The PCV should not be determined on blood collected in NaF/Ox.     

Remission of diabetes mellitus in cats cannot be predicted by the arginine stimulation test

Background: Cats with diabetes mellitus frequently achieve clinical remission, suggesting residual β‐cell function. Responsiveness of β‐cells to arginine persists the longest during diabetes progression, making the intravenous arginine stimulation test (IVAST) a useful tool to assess residual insulin and glucagon secretion. Hypothesis: Diabetic cats with and without remission will have different arginine‐induced insulin or glucagon response. Animals: Seventeen cats with diabetes, 7 healthy cats. Methods: Blood samples collected on admission and during subsequent IVAST. Glucose, insulin, and glucagon were measured. Response to IVAST was assessed by calculating the insulin and glucagon area under the curve (AUC) and the AUC glucagon‐to‐insulin ratio. Diabetic cats were treated with insulin and were followed for 18 weeks. Remission was defined as normoglycemia and disappearance of clinical signs of diabetes for ≥4 weeks, without requiring insulin. Results: Seven diabetic cats (41%) achieved remission. On admission, blood glucose concentration was significantly lower in cats with remission (median, 389 mg/dL; range, 342–536 mg/dL) than in those without remission (median, 506 mg/dL; range, 266–738 mg/dL). After IVAST, diabetic cats with remission had higher AUC glucagon‐to‐insulin ratios (median, 61; range, 34–852) than did cats without remission (median, 26; range, 20–498); glucose, insulin, and glucagon AUCs were not different. Diabetic cats had lower insulin AUC than did healthy cats but comparable glucagon AUC. Conclusions and Clinical Importance: Diabetic cats with and without remission have similar arginine‐stimulated insulin secretion on admission. Although cats with remission had lower blood glucose concentrations and higher AUC glucagon‐to‐insulin ratios, large overlap between groups prevents use of these parameters in clinical practice.     

Influence of medetomidine on stress-related neurohormonal and metabolic effects caused by butorphanol, fentanyl, and ketamine administration in dogs

OBJECTIVE: To examine stress-related neurohormonal and metabolic effects of butorphanol, fentanyl, and ketamine administration alone and in combination with medetomidine in dogs. ANIMALS: 10 Beagles. PROCEDURE: 5 dogs received either butorphanol (0.1 mg/kg), fentanyl (0.01 mg/kg), or ketamine (10 mg/kg) IM in a crossover design. Another 5 dogs received either medetomidine (0.02 mg/kg) and butorphanol (0.1 mg/kg), medetomidine and fentanyl (0.01 mg/kg), medetomidine and ketamine (10 mg/kg), or medetomidine and saline (0.9% NaCI) solution (0.1 mL/kg) in a similar design. Blood samples were obtained for 6 hours following the treatments. Norepinephrine, epinephrine, cortisol, glucose, insulin, and nonesterified fatty acid concentrations were determined in plasma. RESULTS: Administration of butorphanol, fentanyl, and ketamine caused neurohormonal and metabolic changes similar to stress, including increased plasma epinephrine, cortisol, and glucose concentrations. The hyperglycemic effect of butorphanol was not significant. Ketamine caused increased norepinephrine concentration. Epinephrine concentration was correlated with glucose concentration in the butorphanol and fentanyl groups but not in the ketamine groups, suggesting an important difference between the mechanisms of the hyperglycemic effects of these drugs. Medetomidine prevented most of these effects except for hyperglycemia. Plasma glucose concentrations were lower in the combined sedation groups than in the medetomidine-saline solution group. CONCLUSIONS AND CLINICAL RELEVANCE: Opioids or ketamine used alone may cause changes in stress-related biochemical variables in plasma. Medetomidine prevented or blunted these changes. Combined sedation provided better hormonal and metabolic stability than either component alone. We recommend using medetomidine-butorphanol or medetomidine-ketamine combinations for sedation or anesthesia of systemically healthy dogs.     

Acid-base and hormonal abnormalities in dogs with naturally occurring diabetes mellitus

OBJECTIVE: To examine acid-base and hormonal abnormalities in dogs with diabetes mellitus. DESIGN: Cross-sectional study. ANIMALS: 48 dogs with diabetes mellitus and 17 healthy dogs. PROCEDURES: Blood was collected and serum ketone, glucose, lactate, electrolytes, insulin, glucagon, cortisol, epinephrine, norepinephrine, nonesterified fatty acid, and triglyceride concentrations were measured. Indicators of acid-base status were calculated and compared between groups. RESULTS: Serum ketone and glucose concentrations were significantly higher in diabetic than in healthy dogs, but there was no difference in venous blood pH or base excess between groups. Anion gap and strong ion difference were significantly higher and strong ion gap and serum bicarbonate concentration were significantly lower in the diabetic dogs. There were significant linear relationships between measures of acid-base status and serum ketone concentration, but not between measures of acid-base status and serum lactate concentration. Serum insulin concentration did not differ significantly between groups, but diabetic dogs had a wider range of values. All diabetic dogs with a serum ketone concentration > 1,000 micromol/L had a serum insulin concentration < 5 microU/mL. There were strong relationships between serum ketone concentration and serum glucagon-insulin ratio, serum cortisol concentration, and plasma norepinephrine concentration. Serum beta-hydroxybutyrate concentration, expressed as a percentage of serum ketone concentration, decreased as serum ketone concentration increased. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that ketosis in diabetic dogs was related to the glucagon-insulin ratio with only low concentrations of insulin required to prevent ketosis. Acidosis in ketotic dogs was attributable largely to high serum ketone concentrations.     

Neurohormonal and metabolic effects of medetomidine compared with xylazine in beagle dogs

This study was aimed to investigate and compare the effects of medetomidine and xylazine on the blood level of some stress-related neurohormonal and metabolic variables in clinically normal dogs, especially focusing on time and dose relations of the effects. A total of 9 beagle dogs were used for 9 groups, which were treated with physiological saline solution (control), 10, 20, 40, and 80 μg/kg medetomidine, and 1, 2, 4, and 8 mg/kg xylazine, intramuscularly. Blood samples were taken at 10 times during 24 h from a central venous catheter. Plasma norepinephrine, epinephrine, cortisol, glucose, insulin, glucagon, and non-esterified fatty acid concentrations were determined. Both medetomidine and xylazine similarly and dose-dependently inhibited norepinephrine release and lipolysis. Medetomidine suppressed epinephrine release dose-dependently with greater potency than xylazine. Xylazine also tended to decrease epinephrine levels dose-dependently. The cortisol and glucagon levels did not change significantly in any treatment group. Both drugs suppressed insulin secretion with similar potency. Both medetomidine and xylazine increased glucose levels. The hyperglycemic effect of medetomidine, in contrast with xylazine, was not dose-dependent at the tested dosages. The results suggested that the effect of medetomidine on glucose metabolism may not be due only to α₂-adrenoceptor-mediated actions.     

Catecholamine and cortisol responses of horses to incremental exertion

The responses of the plasma concentrations of catecholamines and cortisol in horses to varied relative intensities of exertion were examined. The plasma concentrations of cortisol, epinephrine and norepinephrine increased significantly (p<0.05) with exertion. The plasma cortisol concentrations at relative work intensities of 48.3%±1.4%, 82.3%±2.0% and 99.6%±0.4% of VO_2max were 114%, 124%, and 126%, respectively, of those at rest, whereas the plasma epinephrine concentrations were 239%, 772% and 3483%, and the norepinephrine concentrations were 138%, 255%, and 1121% of the values at rest. There was a significant (p<0.0001) relationship between the plasma epinephrine and norepinephrine concentrations. The blood lactate concentration and the plasma epinephrine and norepinephrine concentrations were significantly (p<0.0001) related, as were the relative work intensity (%VO_2max) and the plasma epinephrine and norepinephrine concentrations. The relationships between the plasma cortisol concentration and work intensity or blood lactate concentration were not significant (p>0.05). This study demonstrates a relationship between relative work intensity and indicators of adrenal medullary and sympathetic activity during brief exertion in horses.     

Evaluation of a Novel Real-Time Continuous Glucose-Monitoring System for Use in Cats

Background: The Guardian REAL‐Time is a continuous glucose‐monitoring system (CGMS) recently developed to provide instantaneous interstitial glucose concentrations; the system does not require a monitor being fixed to the animal. Hypothesis: The CGMS provides accurate and reproducible real‐time readings of glucose concentration in cats. Animals: Thirty‐two diabetic cats, 2 cats with suspected insulinoma, and 5 healthy cats. Methods: Prospective, observational study. CGMS accuracy was compared with a reference glucose meter at normal, high, and low blood glucose concentrations using error grid analysis. Reading variability of 2 simultaneously used CGMS was determined in diabetic cats by calculating correlation and percentage of concordance of paired data at different glycemic ranges. The time interval between increasing glycemia and a rise in interstitial fluid glucose measured by the CGMS was assessed in healthy cats receiving glucose IV; the time point of maximal increase in interstitial glucose concentrations was calculated. Results: The CGMS was 100, 96.1, and 91.0% accurate at normal, high, and low blood glucose concentrations. Measurements deviated from reference by ?12.7 ± 70.5 mg/dL at normal, ?12.1 ± 141.5 mg/dL at high, and ?1.9 ± 40.9 mg/dL at low glucose concentrations. Overall, paired CGMS readings correlated significantly (r= 0.95, P < .0001) and concordance was 95.7%. The median delay after IV administration of glucose to an increase in interstitial glucose was 11.4 minutes (range: 8.8–19.7 minutes). Conclusions and Clinical Importance: Although some readings substantially deviated from reference values, the CGMS yields reproducible results, is clinically accurate in cats with hyperglycemia and euglycemia, and is slightly less accurate if blood glucose concentrations are low. Rapidly increasing interstitial glucose after a glycemic rise suggests that the CGMS is suitable for real‐time measurement under clinical conditions.     

Evaluation of plasma catecholamine and serum cortisol concentrations in horses with colic

OBJECTIVE: To evaluate plasma epinephrine and norepinephrine concentrations and serum cortisol concentration in horses with colic and assess the relationship of these variables with clinical signs, routinely measured clinicopathologic variables, and outcome in affected horses. DESIGN: Prospective observational study. ANIMALS: 35 horses with colic. PROCEDURE: Blood samples were collected within 30 minutes of arrival at the veterinary hospital from horses referred because of colic. Plasma and serum samples were analyzed for cortisol, epinephrine, norepinephrine, lactate, and electrolyte concentrations and acid-base variables. Heart rate at admission and outcome (survival or nonsurvival) were recorded. Univariate logistic regression was used to calculate crude (unadjusted) odds ratios and 95% confidence intervals. RESULTS: Of the 35 horses with colic, 26 survived. Higher plasma epinephrine, plasma lactate, and serum cortisol concentrations were significantly associated with increased risk of nonsurvival, but plasma norepinephrine concentration was not associated with outcome. Plasma epinephrine concentration was significantly correlated with heart rate (r = 0.68), plasma lactate concentration (r = 0.87), blood pH (r = -0.83), anion gap (r = 0.74), and base excess (r = -0.81). CONCLUSIONS AND CLINICAL RELEVANCE: The risk of death appears to be greater in colic-affected horses with high circulating concentrations of epinephrine and cortisol. The correlation of epinephrine with other biochemical markers of illness severity and with heart rate indicates that the degree of sympathetic activation in horses with colic can be inferred from routinely measured variables.     

Influence of infused beta-adrenergic agonists on porcine blood metabolites and catecholamines

Anesthetized pigs were infused sequentially with increased concentrations of beta-adrenergic agonists. At selected times during infusion, blood pressure, heart rate and plasma concentrations of free fatty acids (FFA), glycerol, glucose, lactate, norepinephrine, epinephrine and dopamine were measured. Azaperone, a drug used to calm the pigs before anesthesia, caused hypotension and bradycardia but did not affect plasma metabolites. Infusion of norepinephrine, epinephrine, isoproterenol or clenbuterol produced changes in plasma metabolites and plasma catecholamines. These changes during norepinephrine infusion were attributed to the infused agonist, whereas those during epinephrine infusion might have resulted to some extent from release of norepinephrine. Plasma isoproterenol was not quantified because it interfered with the assay of epinephrine and dopamine so that it was not possible to distinguish between infused isoproterenol and release of endogenous epinephrine and dopamine. Infusion of clenbuterol caused a small increase in plasma norepinephrine so that some of the increase in plasma FFA, glycerol and lactate during clenbuterol infusion may result from release of endogenous norepinephrine.     

Effects of xylazole alone and in combination with ketamine on the metabolic and neurohumoral responses in healthy dogs

ObjectiveTo evaluate the effects of xylazole (an analogue of xylazine), also known as Jingsongling, alone and in combination with ketamine, on metabolic and neurohumoral responses in healthy dogs.Study designProspective randomized experimental study.AnimalsTwelve healthy mongrel dogs (7 male, 5 female, aged 13–20 months, weighing 12.8–15.4 kg).MethodsEach dog received one of two treatments: xylazole 4 mg kg^?1 (group X n = 6); or xylazole 4 mg kg^?1 plus ketamine 10 mg kg^?1 (group XK; n = 6) intramuscularly. Pulse rate (PR), mean arterial pressure (MAP), respiratory rate (f_R), and rectal temperature (RT) were recorded before and from 5 to 100 minutes after drug administration. Venous blood samples were taken before and at intervals from 0.5 to 24 hours after drug administration for determination of plasma concentrations of norepinephrine, epinephrine, β–endorphin, cortisol, insulin, and glucose. Statistical analyses employed anova for repeated measures for changes with time and anova for comparison between treatments.ResultsIn both treatment groups. PR, f_R and RT decreased. MAP increased transiently. At some time points PR, MAP and RT were significantly lower in group X than group XK. Plasma norepinephrine, epinephrine, and insulin concentrations decreased, and β–endorphin and glucose concentrations increased with both treatments. Higher values of plasma norepinephrine, epinephrine, β–endorphin, and glucose concentrations were observed in the XK group compared with the X group.Conclusions and clinical relevanceThis study demonstrates that xylazole administered alone or in combination with ketamine in healthy dogs results in physiological, metabolic and neurohumoral responses similar to those seen after xylazine. Compared with xylazole alone, the combination of xylazole and ketamine reduced some of the responses.     

Effects of the sodium‐glucose cotransporter 2 (SGLT2) inhibitor velagliflozin,a new drug with therapeutic potential to treat diabetes in cats

Sodium‐glucose cotransporter 2 (SGLT2) inhibitors are used in the treatment of human diabetics. They increase glucose excretion and correct hyperglycemia. We examined the investigational SGLT2 inhibitor velagliflozin in two groups of six neutered adult obese cats (equal gender distribution). Placebo (Pl) or drug (D; 1 mg/kg) was administered for 35 days. Routine blood examinations, fructosamine, beta‐hydroxybutyrate (BHB), nonesterified fatty acids (NEFA), glucagon, adiponectin, and leptin were measured before and after treatment, also water intake, and urinary electrolytes, glucose, and volume. Indirect calorimetry, an intravenous glucose tolerance test (IVGTT; 0.8 g/kg) and insulin tolerance test (IVITT) were conducted. All cats tolerated treatment well. Significant changes with D included a decrease in the respiratory exchange ratio, an increase in cholesterol, a small increase in albumin, and a rise in BHB and NEFA. Glucose clearance was unaltered, although less insulin was secreted during the IVGTT (p = .056) suggesting improved insulin sensitivity. IVITT was unchanged. Treatment did not affect glucagon, leptin, or adiponectin. Water intake, urine output, urinary glucose excretion, and the glucose/creatinine ratio but not urinary electrolytes were significantly higher post‐D. We conclude that velagliflozin is a promising drug, which increases urinary glucose excretion in cats and could thereby be beneficial for the treatment of hyperglycemia.     

Plasma endogenous ACTH concentrations and plasma cortisol responses to synthetic ACTH and dexamethasone sodium phosphate in healthy cats

Plasma cortisol responses of 19 healthy cats to synthetic ACTH and dexamethasone sodium phosphate (DSP) were evaluated. After administration of 0.125 mg (n = 5) or 0.25 mg (n = 6) of synthetic ACTH, IM, mean plasma cortisol concentrations increased significantly (P less than 0.05) at 15 minutes, reached a peak at 30 minutes, and decreased progressively to base-line values by 120 minutes. There was no significant difference (P greater than 0.05) between responses resulting from the 2 dosage rates. After administration of 1 mg of DSP/kg of body weight, IV (n = 7), mean plasma cortisol concentrations decreased at postadministration hour (PAH) 1, and were significantly lower than control cortisol concentrations at PAH 4, 6, 8, 10, and 12 (P less than 0.01). Administration of 0.1 mg of DSP/kg, IV (n = 8) or 0.01 mg of DSP/kg, IV (n = 14) induced results that were similar, but less consistent than those after the 1 mg of DSP/kg dosage. Mean plasma cortisol concentrations returned to base-line values by PAH 24. There was not a significant difference between the 3 doses (P greater than 0.05) at most times. Measurement of endogenous ACTH in 16 healthy cats revealed plasma ACTH of less than 20 to 61 pg/ml. Seemingly, administration of synthetic ACTH consistently induced a significant (P less than 0.05) adrenocortical response in healthy cats. On the basis of time-response studies, post-ACTH stimulation cortisol samples should be collected at 30 minutes after ACTH administration to ensure detection of peak adrenocortical response.(ABSTRACT TRUNCATED AT 250 WORDS)     

Acute insulin response to intravenous arginine in nonobese healthy cats

The purpose of this study was to document and characterize insulin response to intravenous administration of arginine, a nonglucose secretagogue, and compare it to insulin response during intravenous glucose tolerance tests (IVGTTs) in clinically healthy nonobese cats. In addition, we examined the influence of plasma glucose level on insulin response to arginine in cats. Five dosages of 10% L-arginine hydrochloride (0.015, 0.025, 0.05, 0.1, and 0.2 g/kg of body weight) were administered to 5 cats. All doses of arginine elicited an abrupt insulin response that peaked at 2-4 minutes and returned to basal concentrations within 30 minutes. Mean insulin peak response (IPR) and mean area under the curve of plasma insulin concentration evaluated for the initial 10 minutes after administration (AUC10) increased with each progressive increase in arginine dosage. An asymptotic maximal response estimated by mean insulin AUC10 reached plateau at 0.1-0.2 g arginine/kg. Arginine at 0.2 g/kg induced hypersalivation in 2 of 4 cats. No adverse effects were evident at lower doses. Mean insulin AUC10 produced by equimolar amount of glucose (0.086 g/kg) was only 42% of that seen in response to 0.1 g arginine/kg, and mean IPR was much lower (18 +/- 7 versus 61 +/- 17 microU/mL). Mild hyperglycemia (211 +/- 6 mg/dL) induced by variable infusion rate of glucose resulted in a significant (P < .05) potentiation of insulin response to arginine; mean insulin AUC10 increased 287 +/- 26 to 551 +/- 167 microU/mL/10 minutes. These findings indicate that the arginine challenge is a more meaningful tool than is the IVGTT for evaluating the insulin secretory capacity in cats.     

Comparison of peritoneal fluid and peripheral blood pH,bicarbonate, glucose,and lactate concentration as a diagnostic tool for septic peritonitis in dogs and cats

OBJECTIVE: To establish a reliable diagnostic tool for septic peritonitis in dogs and cats using pH, bicarbonate, lactate, and glucose concentrations in peritoneal fluid and venous blood. STUDY DESIGN: Prospective clinical study. ANIMALS: Eighteen dogs and 12 cats with peritoneal effusion. METHODS: pH, bicarbonate, electrolyte, lactate, and glucose concentrations were measured on 1- to 2-mL samples of venous blood and peritoneal fluid collected at admission. The concentration difference between blood and peritoneal fluid for pH, bicarbonate, glucose, and lactate concentrations were calculated by subtracting the peritoneal fluid concentration from the blood concentration. Peritoneal fluid was submitted for cytologic examination and bacterial culture. Peritonitis was classified as septic or nonseptic based on cytology and bacterial culture results. RESULTS: In dogs, with septic effusion, peritoneal fluid glucose concentration was always lower than the blood glucose concentration. A blood-to-fluid glucose (BFG) difference > 20 mg/dL was 100% sensitive and 100% specific for the diagnosis of septic peritoneal effusion in dogs. In 7 dogs in which it was evaluated, a blood-to-fluid lactate (BFL) difference < -2.0 mmol/L was also 100% sensitive and specific for a diagnosis of septic peritoneal effusion. In cats, the BFG difference was 86% sensitive and 100% specific for a diagnosis of septic peritonitis. In dogs and cats, the BFG difference was more accurate for a diagnosis of septic peritonitis than peritoneal fluid glucose concentration alone. CONCLUSIONS: A concentration difference > 20 mg/dL between blood and peritoneal fluid glucose concentration provides a rapid and reliable means to differentiate a septic peritoneal effusion from a nonseptic peritoneal effusion in dogs and cats. CLINICAL RELEVANCE: The difference between blood and peritoneal fluid glucose concentrations should be used as a more reliable diagnostic indicator of septic peritoneal effusion than peritoneal fluid glucose concentration alone.     

Stress hyperglycemia in sick cats: a retrospective study over 4 years

Between January 1997 and December 2000 blood glucose concentrations were measured in 2278 sick cats at the time of their initial presentation at the hospital. In 827 cats (36%) hyperglycemia (blood glucose >8 mmol/l) was documented, 1388 cats (61%) had normal blood glucose levels, 63 cats (3%) were hypoglycemic. In 674 of 827 cats (81.5%) no further investigations were performed and the veterinarian judged the hyperglycemia to be stress related. In 153 of the 827 cats (18.5%) blood glucose measurements were repeated and/or serum fructosamine concentrations evaluated. In 106 cats (69%) stress hyperglycemia and in 47 (31%) diabetes mellitus was then diagnosed. Blood glucose concentrations in cats with stress hyperglycemia were between 8.1 and 60.4 mmol/l (Median 10.3), in cats with diabetes mellitus between 8.5 and 70.0 (Median 27.7). Blood glucose concentrations in cats with diabetes mellitus were significantly higher than in cats with stress hyperglycemia. Cats with stress hyperglycemia suffered from a variety of different diseases, the most frequently encountered were surgical problems, neoplasia, heart diseases, upper and lower urinary tract diseases. Blood glucose concentrations in cats with heart diseases and in cats with neoplasia was higher than in cats with other disorders, however, the difference was not significant. Cats with diabetes mellitus were significantly more frequent male castrated than cats with stress hyperglycemia. Cats with stress hyperglycemia were significantly older than cats with normoglycemia.     

Depression of hyperglycemic response to glucagon by parenteral lead administration in sheep.

The insulin and glucose responses to glucagon infusions (27 microgram/hr) were determined in sheep before and after parenteral lead treatment (6 mg/kg intravenously). Glucose production was measured by primed continuous infusion of [6-3H]glucose. Glucagon and insulin concentrations before and during glucagon infusions were not significantly different between lead treatment and control experiments. Lead administration did not affect the concentration or production of glucose in the preinfusion period. However, depressed hyperglycemia during glucagon infusion in lead treated experiments tended to be associated with decreased glucose production. The reduced glucogenic response to glucagon may be the result of reduced function of pyruvate carboxylase, a key hepatic gluconeogenic enzyme in sheep, from lead induced impairment of mitochondrial function.     

The antagonistic effects of atipamezole and yohimbine on stress-related neurohormonal and metabolic responses induced by medetomidine in dogs

This study aimed to compare the antagonistic effects of atipamezole (40, 120, and 320 μg/kg, IM), yohimbine (110 μg/kg, IM), and saline on neurohormonal and metabolic responses induced by medetomidine (20 μg/kg, IM). Five beagle dogs were used in each of the 5 experimental groups in randomized order. Blood samples were taken for 6 h. Medetomidine significantly decreased norepinephrine, epinephrine, insulin, and nonesterified fatty acid levels, and increased plasma glucose levels. Both atipamezole and yohimbine antagonized these effects. The reversal effect of atipamezole was dose-dependency, except on epinephrine. Yohimbine caused prolonged increases in plasma norepinephrine and insulin levels compared to atipamezole, possibly because of its longer half-life elimination. Only yohimbine increased the cortisol levels. Neither glucagon nor lactate levels changed significantly. Based on these findings, when medetomidine-induced sedation is antagonized in dogs, we recommend using atipamezole IM, from 2- to 6-fold the dose of medetomidine, unless otherwise indicated.     

Changes in cortisol concentration in response to stress and postoperative pain in client-owned cats and correlation with objective clinical variables

OBJECTIVE: To identify clinical variables that indicate postoperative pain in cats after ovariohysterectomy in a veterinary hospital setting. ANIMALS: 40 cats. PROCEDURE: Cats were anesthetized and ovariohysterectomized by senior veterinary students. Butorphanol (0.1 mg/kg [n = 20] or 0.3 mg/kg [20] of body weight) was administered IM after surgery. Blood samples were obtained before, during, and after the anesthetic period for measurements of PCV and blood glucose and cortisol concentrations. Clinical variables measured included heart rate, systolic blood pressure, respiratory rate, and rectal temperature. Data for these variables were compared with changes in cortisol concentrations and with similar data-which was used as historical control data-obtained from 20 cats in another study (10 that had been ovariohysterectomized but had not received butorphanol and 10 that had only been anesthetized). RESULTS: Surgical durations were longer in this study, and cats had higher cortisol concentrations, compared with historical control cats. Objective clinical variables did not consistently correlate with changes in cortisol concentration. CONCLUSIONS: Cortisol concentration increased in response to surgical stress and pain. This response was greater in cats in which duration of surgery was longer. CLINICAL RELEVANCE: The objective clinical variables evaluated in this study were not consistent indicators of pain in an uncontrolled, clinical situation.