Clinical studies on canine dirofilarial hemoglobinuria: measured and calculated serum osmolalities and osmolar gap

Serum osmolalities and osmolar gap were determined in 43 normal healthy beagles (control group) and 40 dogs with dirofilarial hemoglobinuria (hemoglobinuria group). In the control group, the measured and calculated serum osmolality levels were in the means of 296 +/- 5 (SD) mOsm/kg and 293 +/- 6 mOsm/kg respectively, showing an osmolar gap less than 10 mOsm/kg. In the hemoglobinuria group, the measured serum osmolality ranged from 272 to 370 mOsm/kg. A considerable number of dogs had normal serum osmolalities in spite of severe intravascular hemolysis, suggesting that the changes in serum osmolality would not be the direct cause of intravascular hemolysis. The measured serum osmolality (331 +/- 28 mOsm/kg) was significantly higher in 11 dogs which died after a surgical removal heartworms than in 29 dogs which recovered after the removal (302 +/- 17 mOsm/kg). The calculated serum osmolality level was 296 +/- 16 mOsm/kg in 24 recovered cases, and 304 +/- 22 mOsm/kg in 10 fatal cases. The osmolar gap stayed in the normal ranges of 5.4 +/- 5.9 mOsm/kg in recovered cases, but it attained a higher level of 22.7 +/- 8.9 mOsm/kg in fatal cases, suggesting poor prognosis in cases with large osmolar gaps. There were significant positive correlations between the measured serum osmolality and osmolar gap, serum sodium, potassium, BUN, GOT, GPT, creatinine, bilirubin and plasma hemoglobin values, as well as between the osmolar gap and serum potassium, BUN, GOT, GPT, creatinine and bilirubin values. The plasma hemoglobin concentration fell markedly without significant change in serum osmolality 20 hr after the heartworm removal.     

Osmolal and anion gaps in dogs with acute endotoxic shock

Serum osmolalities, biochemical concentrations, osmolal and anion gaps, blood lactate concentrations, and acid base status were evaluated in anesthetized, healthy control dogs and in dogs with endotoxic shock. The osmolal gap was not affected by endotoxemia. Compared with control dogs, dogs with endotoxic shock had mildly, though insignificantly, increased anion gaps and significantly increased blood lactate concentrations. The anion gap in dogs with endotoxic shock was positively (r = 0.77) and significantly correlated with the blood lactate concentration. Therefore, the blood lactate concentration of a dog in endotoxic shock may be estimated by use of the equation: lactate = 0.27 (anion gap) - 1.46. Confidence limits for this estimation were calculated. Dogs with endotoxic shock developed a lactic acidosis and hyperchloremic metabolic acidosis, with hyperventilation.     

Glycerol hyperhydration in resting horses

SUMMARY: To determine whether administration of glycerol-containing solutions induces a state of transient hyperhydration in resting euhydrated horses, changes in plasma and urine constituents were measured in four horses for 1 h before and 5 h after nasogastric administration of each of four treatments (Experiment 1). Treatments were applied in a randomized fashion and included: (1) 1.0 g.kg(-)(1)glycerol in 8 L of water (G); (2) 8 L of water (W); (3) 8 L of 0.9% NaCl solution (S); and (4) 1.0 g.kg(-)(1)glycerol in 8 L of 0.9% NaCl solution (GS). In a subsequent study, voluntary water intake was measured hourly for 5 h after nasogastric administration of each treatment (Experiment 2). All treatments produced mild plasma volume expansion ranging from 3.2 to 5.8% in Experiment 1. Administration of glycerol containing solutions increased serum glycerol concentration approximately 100-fold and plasma osmolality (P(osm)) by approximately 10 mOsm/kg and resulted in a tendency towards increased renal water conservation despite increased osmole excretion. In contrast, W treatment decreased plasma and urine osmolality and was accompanied by increased urine production and decreased renal water conservation. Plasma and urine osmolality, as well as renal osmole and water excretion, were unchanged after S administration. In Experiment 2, horses treated with GS voluntarily drank an additional 5.2 +/- 0.9 L of water during the initial hour following nasogastric administration of 8 L of solution. Voluntary water intake with the other treatments was less than 1.0 L for the entire 5 h observation period. Collectively, the results of both experiments suggest that administration of glycerol in saline would produce transient hyperhydration in resting euhydrated horses by enhancing renal water conservation and stimulating voluntary water intake.     

Vasopressin secretion in response to osmotic stimulation and effects of desmopressin on urinary concentrating capacity in dogs with pyometra

OBJECTIVE: To determine vasopressin (VP) secretory capacity during osmotic stimulation and the response to desmopressin treatment in dogs with pyometra and control dogs. ANIMALS: 6 dogs with pyometra before and after ovariohysterectomy and 6 control dogs. PROCEDURE: Urine osmolality (Uosm) was measured during 12 hours. Values measured on the first day defined the basal Uosm pattern. On the second day, dogs were given desmopressin to induce a desmopressin-stimulated Uosm pattern. On day 3, the VP response to osmotic stimulation was examined. RESULTS: Median Uosm on day 1 was 340 mOsm/kg (range, 104 to 1,273 mOsm/kg) and 807 mOsm/kg (range, 362 to 1,688 mOsm/kg) in dogs with pyometra before and after surgery, respectively, and 1,511 mOsm/kg (range, 830 to 1,674 mOsm/kg) in control dogs. Median Uosm during desmopressin treatment was 431 mOsm/kg (range, 168 to 1,491 mOsm/kg) and 1,051 mOsm/kg (range, 489 to 1,051 mOsm/kg) in dogs with pyometra before and after surgery, respectively, and 1,563 mOsm/kg (range, 1,390 to 2,351) in control dogs. In dogs with pyometra, threshold for VP secretion was lower before surgery (median, 340 mOsm/kg; range, 331 to 366 mOsm/kg) than after surgery (median, 358 mOsm/kg; range, 343 to 439 mOsm/kg) or in control dogs (median, 347 mOsm/kg; range, 334 to 360 mOsm/kg). Highest maximum plasma VP values were found in dogs with pyometra. CONCLUSIONS AND CLINICAL RELEVANCE: Dogs with pyometra had increased urine concentration in response to desmopressin but not to the degree of control dogs, whereas VP secretory ability was not reduced.     

Use of the advanced micro-osmometer model 3300 for determination of a normal osmolality and evaluation of different formulas for calculated osmolarity and osmole gap in adult dogs

Objective: To determine a reference interval of whole blood and plasma osmolalities for dogs using the Advanced Micro Osmometer Model 3300, to compare calculated osmolarity to measured osmolality, to determine a reference osmole gap, and to determine the best formula for calculated osmolaity. Design: Prospective, observational. Setting: Tertiary referral and teaching hospital. Animals: One hundred healthy adult dogs. Interventions: None. Measurements: Serum and whole blood biochemistry and osmolality assessments. Results: The mean and median of the measured whole blood osmolality were 323 and 320 mOsm/kg, respectively, with a standard deviation of 13.2 mOsm/kg. The mean and median of the measured plasma osmolality were 313 and 310 mOsm/kg, respectively, with a standard deviation of 13.2 mOsm/kg. The formula that was closest to predicting the measured whole blood and plasma osmolality was ((1.86(Na+K))+(BUN/2.8)+(Glucose/18))/0.93 followed closely by the traditional formula of (2(Na+K))+(BUN/2.8)+(Glucose/18). The mean calculated osmolarities using these formulas were 314.1 and 313.25 mOsm/L, respectively. The mean osmole gap using these formulas was 3.49 and 4.41 mOsm, respectively, for whole blood and ?2.01 and ?1.1 mOsm, respectively, for plasma. Conclusion: The Advanced Micro Osmometer Model 3300 was successful in measuring the osmolality in relative agreement with the current published reference intervals for osmolality. Measured osmolality correlated well with traditional calculated osmolarity.     

Comparison of the techniques of evaluation of urine dilution/concentration in the dog

The objective of this study was to evaluate the quality of the measurement of dog urine dilution/concentration by comparing osmolality with three methods of specific gravity (USG) measurement, i.e. weighing, refractometry and test strips. In unselected urine samples from 182 dogs there was a better agreement between osmolality and USG determination by refractometry (r = 0.92) than by weighing (r = 0.82) or by test strips (r = 0.27). There was an almost linear relationship between osmolality and USG: osmolality (mOsm/kg) = 36646(34318/38974) x (USGref - 1) + 25(-39/88); calculated osmolality differed from measured osmolality by more than 500 mOsm/kg in only 8 of 181 samples. There was a good agreement between USG determination by weighing and refractometry: USGref = 1.000(0.905/1.095) x USGweighing - 0.0004(-0.0019/0.0027), with a moderate bias. Only 12% of the differences between the two methods exceeded 0.010. Test strip assessment of USG was unreliable because of systematic underestimation and should not be used for dog urine. Refractometry is the best technique for routine evaluation of urine concentration/dilution when osmometry is not available.     

Effects of oral isosorbide and glycerol on intraocular pressure,serum osmolality,and blood glucose in normal dogs

Objective To evaluate and compare the effects of oral isosorbide and glycerol on intraocular pressure (IOP), serum osmolality (SOSM), and blood glucose (BG) in normal dogs. Methods Ten normal dogs were administered an oral dose of either isosorbide (1.5 g/kg), glycerol (1.5 g/kg) or control (water, 2 mL/kg) in a double blind protocol. Prior to dosing, baseline IOP, SOSM, and BG were measured in all dogs. IOP was subsequently evaluated every 30 min for 6 h post‐dosing. BG and SOSM were reassessed at times 1, 2, 4, and 6 h post‐dosing. After 1‐week washout periods, every dog was subject to each of the three treatments. The dogs were held NPO for 4 h after dosing. Results The maximal decrease in IOP was 17% by 1 h and 13.5% by 30 min after glycerol and isosorbide administration, respectively. However, the overall changes in IOP were not significant when compared to the controls. SOSM increased above baseline after dosing with glycerol but decreased after isosorbide, which difference was significant at 1, 2, and 4 h post‐administration. BG significantly increased after administration of glycerol relative to the control but was not significantly affected by isosorbide. Conclusions Neither glycerol nor isosorbide significantly affected IOP when compared to the control. However, glycerol induced significant elevations in both BG relative to the control and SOSM relative to isosorbide.     

The effect of intravenous mannitol or oral glycerol on intraocular pressure in dogs

The effect of IV mannitol (1.5 gm/kg) or oral glycerol (1.4 and 2.0 gm/kg) on intraocular pressure (IOP) and serum osmolality (SOSM) was investigated in 24 normal dogs. Mean IOPs were significantly decreased from baseline values from 0.5 through 5.5 hours following mannitol administration with a mean maximum depression of 8.7 +/- 1.8 mm Hg whereas mean SOSM was significantly increased from baseline values. Mean IOPs were significantly decreased from baseline values from 1.0 through 10 hours following oral administration of 1.4 gm/kg glycerol with a mean maximal depression of 5.4 +/- 2.7 mm Hg. Mean SOSM increased initially followed by a significant decrease. The change in IOP following mannitol administration showed less variation (smaller standard deviations) than glycerol (1.4 gm/kg). Five of the 6 dogs that received the 2.0 gm/kg glycerol vomited; the mean IOP and SOSM values were not significantly altered from baseline values in these dogs. Four of 5 dogs given cooled (10C) 2.0 gm/kg glycerol vomited. The incidence of vomiting appeared to be dose related. Both mannitol and glycerol (1.4 gm/kg) are effective for decreasing IOP in normal dogs.     

4-Methylpyrazole as treatment for naturally acquired ethylene glycol intoxication in dogs

Eight dogs with ethylene glycol intoxication were treated with 4-methylpyrazole, an alcohol dehydrogenase inhibitor. Dogs had clinical signs referable to ethylene glycol ingestion including ataxia, depression, vomiting, polyuria, and dehydration. Metabolic abnormalities included high anion gap metabolic acidosis, serum hyperosmolality, isosthenuria, and monohydrate and dihydrate calcium oxalate crystalluria. Serum and urine ethylene glycol concentrations were determined to confirm ingestion of ethylene glycol. A 50-mg/ml solution of 4-methylpyrazole in propylene glycol was administered iv as follows: initial treatment, 20 mg/kg of body weight; at 17 hours after admission, 15 mg/kg; at 25 hours after admission, 5 mg/kg. By 24 hours after admission, all dogs had clinical and metabolic improvement. Of the 8 dogs, 7 were released within 3 days of admission. Four of the 8 dogs returned for follow-up evaluation, at which time biochemical or hematologic abnormalities were not observed.     

Improved conception rates in sows inseminated with cryopreserved boar spermatozoa prepared with a more optimal combination of osmolality and glycerol in the freezing extender

Cryoprotectant agents (CPAs) are added in freezing extenders to prevent intracellular ice crystal formation. However, it has been reported that high dose of CPAs confer toxicity on spermatozoa. Recently, the reduction of intracellular water by a high osmolality solution has also resulted in the suppression of ice crystal formation in spermatozoa, suggesting that the optimal combination of glycerol concentration and freezing extender osmolality could contribute to the development of effective sperm cryopreservation techniques. In this study, we investigated the motility, membrane and acrosomal integrity of frozen-thawed boar spermatozoa treated with freezing extender (NSF) of varying osmolalities (300, 400, 500 mOsm/kg) and final concentrations of glycerol (0.5, 1, 2, 3%). The spermatozoa that were treated at 400 mOsm/kg and 2% glycerol showed significantly higher rates of motility and membrane integrity compared with those in other treatment groups. In addition, the conception and implantation rates of swine artificially inseminated with spermatozoa frozen by the novel freezing extender (conception; 79%, implantation; 57.5%) were significantly higher than those of frozen-thawed spermatozoa treated in the conventional NSF (300 mOsm/kg, 3% glycerol) (conception; 29%, implantation; 33.8%). From these results, we concluded that the novel hyperosmotic (400 mOsm/kg) and low-glycerol (final concentration 2%) freezing extender is beneficial for the cryopreservation of boar spermatozoa.     

Water deprivation test in the dog: maximal normal values.

Studies were undertaken to determine maximal urine osmolality and urine specific gravity following water deprivation for 20 dogs with normal renal function. In addition, the reliability of body weight, skin pliability, total plasma protein concentration, and packed cell volume as indices of negative water balance was assessed. Following water deprivation for periods sufficient to induce dehydration, the mean maximal urine osmolality was 2,289 mOsm/kg. The corresponding mean maximal urine specific gravity was 1.062 and ranged from 1.050 to 1.076. The ratio of mean maximal urine osmolality to mean serum osmolality at the time of peak urine concentration was 7.3. There was no detectable difference in urine concentration indices between males and females. Changes in skin pliability and packed cell volume proved unreliable as estimates of dehydration. Weight loss and increases in total plasma protein concentration proved to be more consistent indicators of hydration status. Abnormal increases in serum urea nitrogen and serum creatinine concentrations occurred rarely, even though some dogs had water withheld for periods of up to 96 hours.     

Intramuscular administration of a low dose of ACTH for ACTH stimulation testing in dogs

OBJECTIVE: To compare adrenal gland stimulation achieved following administration of cosyntropin (5 microg/kg [2.3 microg/lb]) IM versus IV in healthy dogs and dogs with hyperadrenocorticism. DESIGN: Clinical trial. Animals-9 healthy dogs and 9 dogs with hyperadrenocorticism. PROCEDURES: In both groups, ACTH stimulation was performed twice. Healthy dogs were randomly assigned to receive cosyntropin IM or IV first, but all dogs with hyperadrenocorticism received cosyntropin IV first. In healthy dogs, serum cortisol concentration was measured before (baseline) and 30, 60, 90, and 120 minutes after cosyntropin administration. In dogs with hyperadrenocorticism, serum cortisol concentration was measured before and 60 minutes after cosyntropin administration. RESULTS: In the healthy dogs, serum cortisol concentration increased significantly after administration of cosyntropin, regardless of route of administration, and serum cortisol concentrations after IM administration were not significantly different from concentrations after IV administration. For both routes of administration, serum cortisol concentration peaked 60 or 90 minutes after cosyntropin administration. In dogs with hyperadrenocorticism, serum cortisol concentration was significantly increased 60 minutes after cosyntropin administration, compared with baseline concentration, and concentrations after IM administration were not significantly different from concentrations after IV administration. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that in healthy dogs and dogs with hyperadrenocorticism, administration of cosyntropin at a dose of 5 microg/kg, IV or IM, resulted in equivalent adrenal gland stimulation.     

Effect of low doses of cosyntropin on serum cortisol concentrations in clinically normal dogs

OBJECTIVE: To determine the lowest of 5 doses of cosyntropin (1.0, 0.5, 0.1, 0.05, or 0.01 microg/kg) administered IV that stimulates maximal cortisol secretion in clinically normal dogs. ANIMALS: 10 clinically normal dogs. PROCEDURES: 5 dose-response experiments were performed in each of the dogs. Each dog received 5 doses of cosyntropin (1.0, 0.5, 0.1, 0.05, and 0.01 microg/kg) IV in random order (2-week interval between each dose). Serum samples for determination of cortisol concentrations were obtained before (baseline) and at 10, 20, 30, 40, 50, 60, 120, and 240 minutes after cosyntropin administration. RESULTS: Compared with baseline values, mean serum cortisol concentration in the study dogs increased significantly after administration of each of the 5 cosyntropin doses. Mean peak serum cortisol concentration was significantly lower after administration of 0.01, 0.05, and 0.1 microg of cosyntropin/kg, compared with findings after administration of 0.5 and 1.0 microg of cosyntropin/kg. After administration of 0.5 and 1.0 microg of cosyntropin/kg, mean peak serum cortisol concentration did not differ significantly; higher doses of cosyntropin resulted in more sustained increases in serum cortisol concentration, and peak response developed after a longer interval. CONCLUSIONS AND CLINICAL RELEVANCE: Administration of cosyntropin IV at a dose of 0.5 microg/kg induced maximal cortisol secretion in healthy dogs. Serum cortisol concentration was reliably increased in all dogs after the administration of each of the 5 doses of cosyntropin. These data should be useful in subsequent studies to evaluate the hypothalamic-pituitary-adrenal axis in healthy and critically ill dogs.     

Effects of anesthesia, surgery, and intravenous administration of fluids on plasma antidiuretic hormone concentrations in healthy dogs

OBJECTIVE: To evaluate effects of anesthesia, surgery, and intravenous administration of fluids on plasma concentrations of antidiuretic hormone (ADH), concentration of total solids (TS), PCV, arterial blood pressure (BP), plasma osmolality, and urine output in healthy dogs. ANIMALS: 22 healthy Beagles. PROCEDURE: 11 dogs did not receive fluids, and 11 received 20 ml of lactated Ringer's solution/kg of body weight/h. Plasma ADH adn TS concentrations, PCV, osmolality, and arterial BP were measured before anesthesia (T0) and after administration of preanesthetic agents (T1), induction of anesthesia (T2), and 1 and 2 hours of surgery (T3 and T4, respectively). Urine output was measured at T3 and T4. RESULTS: ADH concentrations increased at T1, T3, and T4, compared with concentrations at T0. Concentration of TS and PCV decreased at all times after administration of preanesthetic drugs. Plasma ADH concentration was less at T3 in dogs that received fluids, compared with those that did not. Blood pressure did not differ between groups, and osmolality did not increase > 1% from To value at any time. At T4, rate of urine production was less in dogs that did not receive fluids, compared with those that did. CONCLUSIONS AND CLINICAL RELEVANCE: Plasma ADH concentration increased and PCV and TS concentration decreased in response to anesthesia and surgery. Intravenous administration of fluids resulted in increased urine output but had no effect on ADH concentration or arterial BP. The causes and effects of increased plasma ADH concentrations may affect efficacious administration of fluids during the perioperative period in dogs.     

Intra- and Interindividual Variation in Urine Osmolality and Urine Specific Gravity in Healthy Pet Dogs of Various Ages

Urine specific gravity (Usg) and urine osmolality (Uosm) are used routinely to assess renal concentrating ability, but limited data on these variables are available for healthy dogs. Consequently, we studied the intra- and interindividual variations in Usg and Uosm in healthy dogs as well as the influence of age and gender on these variables. Dogs were selected for health and anestrus in female dogs through the use of a detailed questionnaire. Eighty-nine owners collected morning and evening urine samples from their dogs on 2 consecutive days. In 8 dogs in which the Uosm of different samples varied more than 50%, owners collected urine for 24 hours at 2-hour intervals during the day and at 4-hour intervals at night. The possible effect of changes in adrenocortical function with age was assessed by measurements of urinary corticoid/creatinine (C/C) ratios. Among all samples, Uosm ranged from 161 to 2,830 mOsm/kg and Usg from 1.006 to > 1.050. In the morning, Uosm (1,541 ± 527 mOsm/kg, range 273–2,620 mOsm/kg) and Usg (1.035 ± 0.010, range 1.009- > 1.050) were higher than in the evening (Uosm 1,400 ± 586 mOsm/kg, range 161–2,830 mOsm/kg; Usg 1.031 ± 0.012, range 1.006- > 1.050). The interindividual coefficient of variation in Uosm was 34.2% for morning urine samples and 41.9% for evening samples. In 8 dogs with large differences in urine concentration, there were 2– to 3-fold increases or decreases in Uosm during the day, and the intraindividual coefficient of variation was 33.0%. There was no relation between gender and urine concentration. Urine concentration in both the morning and evening samples decreased with age. Urinary corticoid/creatinine ratios did not change with age. It can be concluded that Uosm and Usg vary widely among healthy dogs. Urine concentration is generally lower in the evening than in the morning and is not related to gender. Urine concentration decreases with age, and this cannot be ascribed to an associated increase in endogenous corticoids. In some dogs, Uosm varies widely during the day, with an intraindividual coefficient of variation approaching the interindividual coefficient of variation. This may be regarded as a biologic variation but also could represent an early undi-agnosed clinical abnormality.     

Comparison of bioavailability of two chloramphenicol preparations in dogs after intramuscular injection.

Aqueous chloramphenicol glycinate was compared with propylene glycol solution of chloramphenicol after equivalent intramuscular doses (22 mg/kg) were given to 10 normal, healthy dogs in a crossover study. Duration and magnitude of plasma concentrations of chloramphenicol were significantly longer and higher with the glycinate than with the propylene glycol solution.     

Effects of urine alkalization and activated charcoal on the pharmacokinetics of orally administered carprofen in dogs

OBJECTIVE: To investigate the effects of oral administration of activated charcoal (AC) and urine alkalinization via oral administration of sodium bicarbonate on the pharmacokinetics of orally administered carprofen in dogs. ANIMALS: 6 neutered male Beagles. PROCEDURES: Each dog underwent 3 experiments (6-week interval between experiments). The dogs received a single dose of carprofen (16 mg/kg) orally at the beginning of each experiment; after 30 minutes, sodium bicarbonate (40 mg/kg, PO), AC solution (2.5 g/kg, PO), or no other treatments were administered. Plasma concentrations of unchanged carprofen were determined via high-performance liquid chromatography at intervals until 48 hours after carprofen administration. Data were analyzed by use of a Student paired t test or Wilcoxon matched-pairs rank test. RESULTS: Compared with the control treatment, administration of AC decreased plasma carprofen concentrations (mean +/- SD maximum concentration was 85.9 +/- 11.9 mg/L and 58.1 +/- 17.6 mg/L, and area under the time-concentration curve was 960 +/- 233 mg/L x h and 373 +/- 133 mg/L x h after control and AC treatment, respectively). The elimination half-life remained constant. Administration of sodium bicarbonate had no effect on plasma drug concentrations. CONCLUSIONS AND CLINICAL RELEVANCE: After oral administration of carprofen in dogs, administration of AC effectively decreased maximum plasma carprofen concentration, compared with the control treatment, probably by decreasing carprofen absorption. Results suggest that AC can be used to reduce systemic carprofen absorption in dogs receiving an overdose of carprofen. Oral administration of 1 dose of sodium bicarbonate had no apparent impact on carprofen kinetics in 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.     

Serum and urine inorganic fluoride concentrations and urine oxalate concentrations following methoxyflurane anesthesia in the dog.

Plasma fluoride, urine fluoride and urine oxalate concentrations were measured before administering an anesthetic to 8 dogs, and at 0, 3, 9, 24, 48, and 72 hours following 1.5 hours of anesthesia with 1% methoxyflurane. Plasma and urine osmolalities were measured and compared with fluoride and oxalate values. Fluoride concentration increased in both plasma and urine following anesthesia when compared with the preanesthetic concentrations. Maximum mean plasma inorganic fluoride was 106.71 mumoles per liter (+/- 25.44 SE) at 9 hours after exposure to methoxyflurane was completed. By 72 hours after exposure to methoxyflurane the plasma fluoride concentration was 23.47 microM/L (+/- 5.74 SE). Mean urine inorganic fluoride concentration was highest at 9 hours after exposure to methoxyflurane and reached 6047.03 microM/L (+/- 1378.46 SE) as compared to the mean preanesthetic base-line concentration of 542.68 microM/L (+/- 132.93 SE), and the 72 hour mean urine fluoride concentration which was 1593.78 microM/L (+/- 579.46 SE). Urine oxalate concentrations, when compared with urine osmolality (mg/mOsm), increased throughout the study. The 72-hour concentration after exposure to methoxyflurane was 2.5 times the preanesthetic (mg/mOsm) oxalate concentration. Plasma osmolality did not change markedly during the study. Urine osmolalities varied between animals and collection times, but a consistent pattern did not occur. Clinical and laboratory signs of renal dysfunction were not observed in any animal during the study.     

Relationships between glucose, sodium and effective osmolality in diabetic dogs and cats

Objective: To examine the relative contributions of sodium and glucose to serum effective osmolality and the presence of abnormalities of sodium and osmolality in diabetic dogs and cats. Design: Retrospective study. Setting: A university‐based referral hospital. Animals: Diabetic dogs (n=14) and cats (n=13) consecutively admitted to the hospital over a 6‐month period. Interventions: None Measurements: Serum biochemistry assessments. Main results: The mean glucose concentration was higher in diabetic dogs than in diabetic cats. Total osmolality (Osm_T), effective osmolality (Osm_E), and the concentrations of sodium, potassium, blood urea notrogen, bicarbonate, and creatinine did not differ between species. Sodium abnormalities and hyperosmolality affected 44% and 81%, respectively, of the study group. However, marked hyperosmolality (Osm_E>330 mOsm/L) was found in only 33% of the study group. Serum sodium correlated closely with Osm_E in dogs and cats but serum glucose did not correlate with the Osm_E in either species. Subsets of dogs (n=10) and cats (n=7) with diabetic ketosis (DK) were examined separately. DK dogs had significantly lower sodium concentrations than DK cats and the proportion of DK dogs with hyponatremia was nearly 3 times greater than DK cats. Severe hyperosmolality (Osm_E>330 mOsm/L) was more common in DK cats than DK dogs. Conclusions: In diabetic dogs and cats, sodium, not glucose, was correlated with serum Osm_E and marked elevation in pretreatment Osm_E is uncommon. Compensatory reduction in serum sodium may be 1 mechanism for blunting changes in Osm_E in the presence of marked hyperglycemia.