Alterations in Carbohydrate Metabolism in Canine Lymphoma

Following an overnight fast, blood samples were obtained from 14 dogs with previously untreated lymphoma before and 5, 15, 30, 45, 60, and 90 minutes following an intravenous challenge with 500 mg/kg dextrose. Samples were assayed for glucose, lactate, and insulin concentrations and compared statistically with ten control dogs of similar weight and age undergoing an identical dextrose challenge. Dogs with lymphoma had similar glucose tolerance curves when compared with controls. Lactate concentrations were significantly higher (P less than 0.001) at baseline and all time periods of the glucose tolerance test in dogs with lymphoma when compared with controls. Rise in lactate concentrations over baseline levels in the first 30 minutes of the glucose tolerance test were significantly higher in dogs with lymphoma (P = 0.011). Insulin concentrations were significantly higher (P less than 0.001) at baseline and at the 5-, 45-, 60-, and 90-minute time periods of the glucose tolerance test in dogs with lymphoma. Rise in insulin concentrations over baseline in the first 5 minutes of the glucose tolerance test were also significantly greater in dogs with lymphoma (P = 0.021). These results indicate carbohydrate metabolism is altered in dogs with lymphoma. Many of these alterations parallel those observed in human patients suffering from cancer cachexia making canine lymphoma a potential model for further study of the pathogenesis and therapy of cancer cachexia.     

Effects of lactated Ringer solution and prednisolone sodium succinate on dogs with induced hemorrhagic shock.

Hemorrhagic shock was induced in nonsplenectomized dogs by removing 41% of their blood volume over a 15-minute period. Hemodynamic and metabolic variables were determined prior to and for 3 hours after completion of hemorrhage. One group of 5 dogs was not treated. After the 30-minute sample was collected, a second group of 5 dogs was given lactated Ringer solution (LRS) at 88 ml/kg of body weight, IV. A third group of 5 dogs was given LRS (88 ml/kg, IV) and prednisolone sodium succinate (11 mg/kg, IV) 30 minutes after hemorrhage. The IV administration of LRS was completed within 15 minutes. The glucocorticoid was administered as an IV bolus after 500 ml of LRS had been given. The large volume and administration of LRS significantly (P = 0.05) improved many of the hemodynamic and metabolic effects of acute hemorrhage and hemorrhagic shock. At one time or another during the 2.5-hour observation period after the initiation of treatment, mean arterial pressure, cardiac index, systemic vascular resistance, heart rate, respiratory rate, lactate, glucose, and arterial and venous blood gas values were significantly (P = 0.05) improved, compared with baseline values. The addition of prednisolone sodium succinate to the treatment regimen improved the effectiveness of LRS alone only in some dogs at random sampling times. Significant trends were not observed except, possibly, the improvement of venous pH and A-V pH and PCO2 differences.     

Alterations in Lipoprotein Profiles in Dogs With Lymphoma

After a 12-hour fast, blood samples were obtained from 31 dogs with previously untreated lymphoma. Blood samples were also collected from 16 of these dogs after up to 5 treatments with doxorubicin (30 mg/m² intravenously every 3 weeks). All 16 dogs underwent complete remission. Five dogs were re-evaluated after relapse and after overt signs of cancer cachexia had become clinically apparent. Samples were assayed for 8 quantitative parameters: total cholesterol (T-CH) and total triglyceride (T-TG) concentrations, and the concentration of cholesterol and triglyceride in each of the three major lipoprotein fractions, very-low-density lipoprotein (VLDL-CH and VLDL-TG), low-density lipoprotein (LDL-CH and LDL-TG), and high-density lipoprotein (HDL-CH and HDL-TG). The results were compared with those from 20 healthy control dogs of similar weight and age before and 3 weeks after being given one dose of doxorubicin (30 mg/m² intravenously). The administration of doxorubicin to control dogs resulted in a significant (P> .05) decrease in T-CH, LDL-CH, and HDL-CH, as well as a significant increase in VLOL-TG and HDL-TG. When compared with untreated controls, untreated dogs with lymphoma had significantly higher concentrations of VLDL-CH, T-TG, VLDL-TG, LDL-TG, and HDL-TG, and significantly lower concentrations of HDL-CH. HDL-TG and VLDL-TG concentrations from dogs with lymphoma were significantly increased above pretreatment values after relapse and development of overt signs of cancer cachexia. Dogs in remission that were evaluated after one dose of doxorubicin had significantly higher concentrations of T-CH, VLDL-CH, T-TG, and LDL-TG when compared with controls that were evaluated after an identical dose of doxorubicin. HDL-TG increased significantly over pretreatment values in dogs with lymphoma after doxorubicin therapy. These results suggest that dogs with lymphoma have significant alterations in lipid profiles, and with the possible exception of HDL-CH, these abnormalities do not normalize when clinical remission is obtained.     

Antioxidant Status and Biomarkers of Oxidative Stress in Dogs with Lymphoma

Background: Oxidative stress might play a role in carcinogenesis, as well as impacting morbidity and mortality of veterinary cancer patients. The purpose of this study was to evaluate antioxidant concentrations and biomarkers of oxidative stress in dogs with newly diagnosed lymphoma before treatment and once in remission, with comparison with healthy controls.
Hypothesis: Dogs with lymphoma have increased oxidant and reduced antioxidant concentrations compared with healthy controls, and that these abnormalities normalize once remission is achieved.
Animals: Seventeen dogs with lymphoma and 10 healthy controls.
Methods: Prospective, observational study. Measures of oxidative stress [malondialdehyde and total isoprostanes (isoP)] and antioxidants [α-tocopherol, γ-tocopherol, oxygen radical absorbance capacity (ORAC), and glutathione peroxidase (GSHPx)] were assessed in dogs with newly diagnosed lymphoma before treatment compared with healthy control dogs. The same parameters were measured in the dogs with lymphoma on week 7 of the chemotherapy protocol when all dogs were in remission.
Results: At baseline, dogs with lymphoma had significantly lower α-tocopherol ( P <.001) and γ-tocopherol ( P = .003) but higher GSHPx ( P = .05), ORAC ( P = .001), and isoP ( P < .001) compared with healthy controls. In the dogs with lymphoma, α-tocopherol concentrations were higher ( P = .005) and ascorbic acid were lower ( P = .04) after treatment.
Conclusions and Clinical Importance: Results suggest that dogs with lymphoma have alterations in oxidant and antioxidant concentrations and that the status of some of these biomarkers normalize after remission. Further studies are warranted to determine whether antioxidant interventions to correct these are beneficial in the treatment of canine lymphoma.     

Effects of 6% hetastarch (600/0.75) or lactated Ringer's solution on hemostatic variables and clinical bleeding in healthy dogs anesthetized for orthopedic surgery

ObjectiveTo evaluate and compare hemostatic variables and clinical bleeding following the administration of 6% hetastarch (600/0.75) or lactated Ringer’s solution (LRS) to dogs anesthetized for orthopedic surgery.Study designRandomized blinded prospective study.AnimalsFourteen, healthy adult mixed-breed hound dogs of either sex, aged 11–13 months, and weighing 20.8 ± 1.2 kg.MethodsThe dogs were randomly assigned to receive a 10 mL kg^?1 intravenous (IV) bolus of either 6% hetastarch (600/0.75) or LRS over 20 minutes followed by a maintenance infusion of LRS (10 mL kg^?1hour^?1) during anesthesia. Before (Baseline) and at 1 and 24 hours after bolus administration, packed cell volume (PCV), total protein concentration (TP), prothrombin time (PT), activated partial thromboplastin time (APTT), von Willebrand’s factor antigen concentration (vWF:Ag), factor VIII coagulant activity (F VIII:C), platelet count, platelet aggregation, colloid osmotic pressure (COP) and buccal mucosal bleeding time (BMBT) were measured. In addition a surgeon who was blinded to the treatments assessed bleeding from the incision site during the procedure and at 1 and 24 hours after the bolus administration.ResultsFollowing hetastarch or LRS administration, the PCV and TP decreased significantly 1-hour post-infusion. APTT did not change significantly compared to baseline in either treatment group, but the PT was significantly longer at 1-hour post-infusion than at 24 hours in both groups. No significant change was detected for vWF:Ag, FVIII:C, platelet aggregation or clinical bleeding in either group. The BMBT increased while platelet count decreased significantly at 1-hour post-infusion in both groups. The COP decreased significantly in both treatment groups 1-hour post-infusion but was significantly higher 1-hour post-infusion in the hetastarch group compared to the LRS group.Conclusions and clinical relevanceAt the doses administered, both hetastarch and LRS can alter hemostatic variables in healthy dogs. However, in these dogs undergoing orthopedic surgery, neither fluid was associated with increased clinical bleeding.     

Effects of oral administration of a commercial activated charcoal suspension on serum osmolality and lactate concentration in the dog

The purpose of this investigation was to determine the effects of an activated charcoal (AC) suspension containing propylene glycol and glycerol on serum osmolality, osmolal gap, and lactate concentration in dogs. Six healthy adult dogs were administered 4 g/kg AC in a commercially available suspension that contained propylene glycol and glycerol as vehicles. Blood samples were taken before and 1, 4, 6, 8, 12, and 24 hours after the administration of the test suspension. Samples were analyzed for osmolality, blood gases, and concentrations of lactate, sodium, potassium, serum urea nitrogen, and glucose. Osmolal gaps were calculated for each time point. Mean serum osmolality, osmolal gap, and lactate concentration were significantly increased after suspension administration compared to baseline. Serum osmolality increased from 311 mOsm/kg at baseline to 353 mOsm/kg, osmolal gap increased from 5 to 52 mOsm/kg, and lactate concentration increased from 1.9 to 4.5 mmol/L after suspension administration (all P < .01). Three of the 6 dogs vomited between 1 and 3 hours after the administration of the test suspension, and 4 of 6 dogs were lethargic. All dogs drank frequently after AC administration. Commercial AC suspension administered at a clinically relevant dose increases serum osmolality, osmolal gap, and lactate concentration in dogs. These laboratory measures and the clinical signs of vomiting, lethargy, and increased frequency of drinking might complicate the diagnosis or monitoring of some intoxications (such as ethylene glycol) in dogs that have previously received AC suspension containing propylene glycol, glycerol, or both as vehicles.     

Endometrial concentrations of ampicillin in mares after intrauterine infusion of the drug

Serum concentration of ampicillin, a semisynthetic penicillin, was measured in mares at various time intervals up to 24 hours after intrauterine infusion of 3 g of ampicillin. Blood samples were drawn immediately before infusion and at 1-, 4-, 10- and 24-hour intervals after infusion. At postinfusion hour 24, two endometrial biopsy specimens were obtained to measure endometrial concentrations of ampicillin. Blood was drawn twice as part of the 24-hour postinfusion sample collection, once before removal of the biopsy specimens and again 5 minutes after removal of the biopsy specimens. After drug infusion, more diestrous mares had detectable serum ampicillin concentration than did estrous mares for all samples, except the 24-hour prebiopsy sample. None of the 24-hour prebiopsy serum samples had detectable ampicillin concentration, but ampicillin was detected in the serum of 4 of 5 diestrous mares after endometrial biopsy. Endometrial concentrations of ampicillin were detectable at postinfusion hour 24 in estrous and diestrous mares, but were not different. All 24-hour biopsy specimens had ampicillin concentrations greater than the ampicillin minimal inhibitory concentration.     

Suppression of preovulatory luteinizing hormone surges in heifers after intrauterine infusions of Escherichia coli endotoxin

A study was conducted to test the hypothesis that high cortisol concentrations associated with products of infections (endotoxin) cause derangement in the neuroendocrine mechanism controlling ovulation in heifers. Eight Holstein heifers were given 2 injections of prostaglandin (PG), 11 days apart, to synchronize estrus. Starting from 25 hours after the second injection of PG (PG-2), the uterus of each heifer was infused with 5 ml of pyrogen-free water (control, n = 3) or Escherichia coli endotoxin (5 micrograms/kg of body weight) in 5 ml of pyrogen-free water (treated, n = 5), once every 6 hours for 10 treatments. Blood samples were obtained every 15 minutes via indwelling jugular catheter for an hour before and 2 hours after each infusion, then hourly until an hour before the next infusion. Ultrasonography of the ovaries was performed every 12 hours, starting 24 hours after PG-2 injection until 96 hours after PG-2 injection. Serum concentrations of luteinizing hormone and cortisol were determined by validated radioimmunoassays. Changes in cortisol concentrations were not detected in control heifers with preovulatory luteinizing hormone surges at 60 to 66 hours after PG-2 injection, followed by ovulations 72 to 96 hours after PG-2 was injected. None of the treated heifers ovulated, and the resulting follicular cysts (14 to 18 mm diameter) persisted for 7 to 21 days. In all treated heifers, serum cortisol concentrations increased (4- to 10-fold) during the first 2 hours after each infusion and then decreased gradually until the next infusion. Luteinizing hormone concentrations remained at baseline values throughout the treatment period in all treated heifers.(ABSTRACT TRUNCATED AT 250 WORDS)     

Duration of pituitary and adrenocortical suppression after long-term administration of anti-inflammatory doses of prednisone in dogs.

Duration and magnitude of hypothalamic-pituitary-adrenal axis suppression caused by daily oral administration of a glucocorticoid was investigated, using an anti-inflammatory dose of prednisone. Twelve healthy adult male dogs were given prednisone orally for 35 days (0.55 mg/kg of body weight, q 12 h), and a control group of 6 dogs was given gelatin capsule vehicle. Plasma cortisol (baseline and 2-hour post-ACTH administration) and plasma ACTH and cortisol (baseline and 30-minutes post corticotropin-releasing hormone [CRH] administration) concentrations were monitored biweekly during and after the 35-day treatment period. Baseline plasma ACTH and cortisol and post-ACTH plasma cortisol concentrations were significantly (P less than 0.05) reduced in treated vs control dogs after 14 days of oral prednisone administration. By day 28, baseline ACTH and cortisol concentrations remained significantly (P less than 0.05) reduced and reserve function was markedly (P less than 0.0001) reduced as evidenced by mean post-CRH ACTH, post-CRH cortisol, and post-ACTH cortisol concentrations in treated vs control dogs. Two weeks after termination of daily prednisone administration, significant difference between group means was not evident in baseline ACTH or cortisol values, post-CRH ACTH or cortisol values, or post-ACTH cortisol values, compared with values in controls. Results indicate complete hypothalamic-pituitary-adrenal axis recovery 2 weeks after oral administration of an anti-inflammatory regimen of prednisone given daily for 5 weeks.     

Duration of etomidate-induced adrenocortical suppression during surgery in dogs

Plasma cortisol concentrations were compared in canine surgical patients given etomidate (2 mg/kg of body weight, IV) or thiopental sodium (12 mg/kg, IV) for anesthetic induction. Blood samples to determine plasma concentrations of etomidate were obtained at 0, 5, 10, 15, and 30 minutes and 1, 2, 3, 4, 5, 6, 8, 12, and 24 hours after induction. Adrenocortical function was evaluated before surgery by use of adrenocorticotropic hormone stimulation tests. Dogs in both induction groups had high plasma cortisol concentrations after induction. Dogs given thiopental had a significant increase (P less than 0.05) in plasma cortisol concentration from baseline at 2, 3, 4, 5, 6, 8, and 12 hours after induction. Dogs given etomidate had a significant increase (P less than 0.05) in plasma cortisol concentration from baseline at 5, 6, and 8 hours after induction. A comparison of plasma cortisol concentrations determined at 2, 3, 4, 5, and 6 hours after induction with thiopental or etomidate revealed a higher (P less than 0.05) concentration in dogs given thiopental. The disposition of etomidate was best described by a 2-compartment model, with a redistribution half-life of 0.12 +/- 0.04 minute and a terminal half-life of 1.70 +/- 0.27 minute. Plasma cortisol concentrations did not correlate with plasma etomidate concentrations. We conclude that, compared with thiopental, a single bolus injection of etomidate reduces the adrenocortical response to anesthesia and surgery from 2 to 6 hours after induction. Because cortisol concentrations were significantly higher than baseline, and because cardiopulmonary function is maintained after a single bolus injection of etomidate, it can be considered a safe induction agent in dogs.     

Effects of oral administration of furosemide and torsemide in healthy dogs

OBJECTIVE: To investigate the diuretic effects, tolerability, and adverse effects of furosemide and torsemide after short- and long-term administration in healthy dogs. ANIMALS: 8 mixed-breed dogs. PROCEDURES: In a crossover study, furosemide (2 mg/kg), torsemide (0.2 mg/kg), or placebo (bifidobacterium [1 mg/kg]) was administered orally to each dog every 12 hours for 14 days. Blood and urine samples were collected before the study (baseline data) and at intervals on the 1st (short-term administration) and 14th day (long-term administration) of treatment for assessment of urine volume and specific gravity and selected clinicopathologic variables including BUN, creatinine, and aldosterone concentrations, and creatinine clearance. RESULTS: Compared with the baseline value, short-term administration of furosemide or torsemide immediately increased urine volume significantly; after long-term administration of either drug, urine specific gravity decreased significantly. Compared with the effect of placebo, the 24-hour urine volume was significantly increased after short-term administra-tion of furosemide or torsemide. In addition, it was significantly increased after long-term administration of torsemide, compared with that of short-term administration. Long-term administration of furosemide or torsemide increased the BUN and plasma creatinine con-centrations, compared with the baseline value. Compared with the baseline value, plasma aldosterone concentration was significantly increased after long-term administration of either drug and was significantly higher after torsemide treatment than after furosemide treatment. CONCLUSIONS AND CLINICAL RELEVANCE: In dogs, diuretic resistance developed after 14 days of furosemide, but not torsemide, administration; however, both loop diuretics were associated with increased BUN and plasma creatinine concentrations, compared with values before treatment.     

Serial blood lactate concentrations in systemically ill dogs

BACKGROUND: Lactate concentration often is quantified in systemically ill dogs and interpreted based on human data. To our knowledge, there are no published clinical studies evaluating serial lactate concentrations as a prognostic indicator in ill dogs. OBJECTIVES: Our objective was to perform a prospective study, using multivariate analysis, to determine whether serial lactate concentrations were associated with outcome in ill dogs requiring intravenous fluids. METHODS: Eighty sick dogs had lactate concentrations evaluated, using an analyzer that measures lactate in the plasma fraction of heparinized whole blood, at 0 hours and 6 hours after initiation of treatment. Severity of illness and outcome (survivor, nonsurvivor) were determined by reviewing the patient's record 2 weeks after admission. Lactate concentrations, age, body weight, gender, and severity of illness were evaluated using multivariate analysis to determine their effects on outcome. RESULTS: Dogs with lactate concentrations greater than the reference interval at 6 hours were 16 times (95% confidence interval = 2.32-112.71 times, P <.01) more likely not to survive compared to dogs with lactate concentrations within the reference interval. Lactate concentrations above the reference interval at 0 hours were not significantly related to outcome. However, hyperlactatemia that did not improve by > or = 50% within 6 hours was significantly associated with mortality (P = .024). CONCLUSION: Dogs with a lactate concentration higher than the reference interval at 6 hours were more likely not to survive. These results indicate an association between lactate concentration and outcome and emphasize the importance of serial lactate concentrations in evaluating prognosis.     

Effect of fasting on thyroxine, 3,5,3'-triiodothyronine, and cortisol concentrations in serum of dogs

The present study was designed to compare basal and stimulated concentrations of 3,5,3'-triiodothyronine (T3), thyroxine (T4), and cortisol in serum of dogs fasted 12 or 18 hours (to represent overnight fasting) or 24 or 36 hours (to represent prolonged inappetence) with those of dogs that were not fasted. Twenty-five adult Beagle bitches were allotted to 5 experimental fasting groups (0, 12, 18, 24, and 36 hours). Blood samples for hormonal analyses were obtained 4, 3, 2, and 1 hour before food was removed; at the time of food removal; 1 hour after food was removed; and every 2 hours during experimental fasting until 0800 hours on the day fasting ended. Dogs were injected with 5 IU of thyrotropin, IV, and 2.2 IU of adrenocorticotropin/kg, IM, to evaluate thyroidal and adrenocortical endocrine reserves. Additional blood samples were collected 0.5, 1, 2, 3, and 4 hours after injections were given. Serum concentrations of T3, T4, and cortisol were determined by validated radioimmunoassays. Body weights and ages of the dogs and food consumption during a 2-hour preliminary feeding period before dogs were fasted did not differ among fasting groups. Length of fasting did not affect serum concentrations of T3 or T4 in dogs at 12, 18, 24, or 36 hours after food was removed. Mean serum concentrations of cortisol in dogs fasted 12 or 24 hours were lower than those in dogs that were not fasted. Serum concentrations of the hormones after thyrotropin and adrenocorticotropin were injected were not affected by fasting.(ABSTRACT TRUNCATED AT 250 WORDS)     

Plasma and urine nitric oxide concentrations in horses given below a low dose of endotoxin.

OBJECTIVE: To quantify plasma and urine nitric oxide (NO) concentrations before and after low-dose endotoxin infusion in horses. ANIMALS: 11 healthy adult female horses. Procedure-Eight horses were given endotoxin (35 ng/kg of body weight,i.v.) over 30 minutes. Three sentinel horses received an equivalent volume of saline (0.9% NaCl) solution over the same time. Clinical signs of disease and hemodynamic variables were recorded, and urine and plasma samples were obtained to measure NO concentrations prior to endotoxin infusion (t = 0) and every hour until postinfusion hour (PIH) 6, then every 2 hours until PIH 24. Blood for hematologic and metabolic analyses and for serum cytokine bioassays were collected at 0 hour, every hour until PIH 6, every 2 hours through PIH 12, and finally, every 6 hours until PIH 24. RESULTS: Differences in plasma NO concentrations across time were not apparent, but urine NO concentrations significantly decreased at 4 and 20 to 24 hours in endotoxin-treated horses. Also in endotoxin-treated horses, alterations in clinical signs of disease, and hemodynamic, metabolic, and hematologic variables were significant and characteristic of endotoxemia. Serum interleukin-6 (IL-6) activity and tumor necrosis factor (TNF) concentrations were increased above baseline values from 1 to 8 hours and 1 to 2 hours, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Plasma and urine NO concentrations did not increase in horses after administration of a low dose of endotoxin, despite induction of an inflammatory response, which was confirmed by increased TNF and IL-6 values characteristic alterations in clinical signs of disease, and hematologic, hemodynamic and metabolic variables.     

Effect of timing of blood collection on serum phenobarbital concentrations in dogs with epilepsy

OBJECTIVE: To determine whether there are therapeutically relevant changes in serum phenobarbital concentrations throughout a daily dosing interval in epileptic dogs receiving phenobarbital for > or = 3 weeks. DESIGN: Prospective study. ANIMALS: 33 epileptic dogs receiving phenobarbital. PROCEDURE: Serum phenobarbital concentrations were measured at 0 hour (trough), 3 hours, and 6 hours after oral administration of phenobarbital in epileptic dogs that had received phenobarbital twice daily for a minimum of 3 weeks. For each dog, trough, 3-hour, and 6-hour serum phenobarbital concentrations were evaluated to determine whether they were within the same therapeutic category (lower, middle, or upper end of the therapeutic range of 15 to 45 micrograms/ml), or whether there was a > 30% change in serum concentrations throughout the day. RESULTS: Ninety-one percent (30/33) of dogs had trough, 3-hour, and 6-hour serum phenobarbital concentrations in the same therapeutic category. Only 9% (3/33) of dogs had trough, 3-hour, and 6-hour serum concentrations in different therapeutic categories with a > 30% change in concentrations throughout the day. Significant differences were not detected among mean serum phenobarbital concentrations when comparing the trough, 3-hour, and 6-hour samples for all dogs. CONCLUSIONS AND CLINICAL RELEVANCE: There is no therapeutically relevant change in serum phenobarbital concentrations throughout a daily dosing interval in most epileptic dogs. Therefore, timing is not important when collecting blood samples to measure serum phenobarbital concentrations in most epileptic dogs treated long-term with phenobarbital.     

Effect of hypertonic and isotonic saline solutions on plasma constituents of conscious horses.

Blood constituents and vascular volume indices were determined in 5 standing horses by use of 2-period crossover experimental design. Horses were either administered hypertonic (2,400 mosm/kg of body weight, i.v.) or isotonic (300 mosm/kg, i.v.) saline solution. Each solution was administered at a dosage of 5 ml/kg (infusion rate, 80 ml/min). Samples for determination of PCV, plasma volume, blood volume, plasma osmolality, total amount of plasma protein and plasma concentrations of protein, Na, K, and Cl were collected at 0 hour (baseline, before fluid infusion) and 0.5 hour (at the end of fluid infusion), and subsequently, at 0.25- or 0.5-hour intervals for 4.5 hours. All horses were given the predetermined dose of fluids by 0.5 hour after beginning the saline infusion. Values of P < or = 0.05 were considered significant. Administration of hypertonic saline solution was associated with decreased mean body weight by 4.5 hours, but weight change after isotonic saline administration was not significant. Other than body weight and plasma protein concentration, between-trial difference (treatment effect) was not observed for any measured variable or index. The F values indicated that increasing the number of horses would have not changed these results. A time effect was evident across both trials, so that mean (+/- SD) plasma volume increased (12.3 +/- 1.07%) and mean plasma protein concentration (-12.1 +/- 1.03%) and PCV (-11.9 + 0.67%) decreased proportionately and transiently in association with administration of either fluid at that volume. Other time effects included increased plasma osmolality and Na and Cl concentrations. Blood volume estimates and total amount of plasma protein remained unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of acute induced metabolic alkalosis on the acid/base responses to sprint exercise of six racing greyhounds

To investigate the effect of acute induced metabolic alkalosis on the haematological, biochemical and metabolic responses to sprint exercise, six greyhound dogs with previously placed carotid artetrial catheters were raced four times over a distance of 400 metres. Each dog was raced twice after receiving oral sodium bicarbonate solution (NaHCO₃) (400 mg kg⁻¹) or lactated Ringer's solution ( ). Before, and for intervals of up to one hour after, the exercise arterial blood samples were collected for the measurement of blood gases, packed cell volume, total protein, serum biochemistry and plasma lactate. The time to complete the 400 metre sprint ranged from 32·7 seconds to 36·9 seconds. There was no significant difference in racing times between the dogs treated with NaHCO₃ and , and there was no significant difference between the plasma lactate measurements after the treatments with NaHCO₃ or . Serum chloride concentrations were significantly lower after NaHCO₃ than after LRS, and there was a trend towards a lower serum potassium concentration after NaHCO₃ treatment. Plasma lactate concentrations showed a similar increase and time course of disappearance after both LRS and NaHCO₃ treatments. There were significant changes in all the parameters measured after the exercise, but there were large variations between individual dogs and between races when the dogs were receiving the same treatment.     

Comparison of two doses of aqueous bovine thyrotropin for thyroid function testing in dogs

Thyroid function was evaluated in 20 healthy dogs by thyrotropin (TSH) response testing. Two dose regimens were used: 5 IU of TSH given IV and 1 IU of TSH given IV. Blood samples were collected prior to and at 4 and 6 hours after TSH administration. Serum was obtained and analyzed for total 3,5,3'-tri-iodothyronine and thyroxine (T4) concentrations by radioimmunoassay. All dogs were classified as euthyroid on the basis of response to 5 IU of TSH at 4 and 6 hours. The 1-IU dose of TSH failed to induce adequate increase in T4 concentration in 7 dogs at 4 and 6 hours when the criteria for normal response were post-TSH serum concentration T4 greater than or equal to 3.0 micrograms/dl and serum T4 increase by greater than or equal to 100% over baseline serum T4 concentration. One IU of TSH induced increase in serum T4 concentration over baseline; however, the increase was significantly (P less than 0.05) less than that in response to a 5-IU dose at 6 hours after administration of TSH.     

Intestinal permeability and absorption in dogs with traumatic injury

The objectives of this study were to assess the feasibility of using urinary recovery of sugars to evaluate intestinal permeability and absorption in dogs with traumatic injury and to determine if intestinal permeability and absorption are altered in dogs with traumatic injury. After a 6-hour fast, a sugar solution containing lactulose, rhamnose, 3-0-methyl-D-glucose, and xylose was administered via nasoesophageal tube. Urine was collected and quantitated over the 6-hour study period via closed collection urinary catheters. Urinary sugar recoveries were measured by high-pressure anion exchange liquid chromatography and pulsed amperometric detection. Urinary sugar recoveries in the trauma group at 24, 48, and 72 hours after trauma were compared to normal controls. In addition, severity of trauma was compared to urinary sugar recoveries. Twelve client-owned dogs with traumatic injury and 6 healthy controls were enrolled in the study. Lactulose recovery and the lactulose:rhamnose recovery ratio were significantly higher in the trauma group at 48 hours but were no longer different from controls by 72 hours. Xylose recovery was significantly higher in the trauma group when compared to controls at 72 hours, whereas 3-O-methyl-D-glucose recovery was significantly lower in the trauma group at 24 hours. The xylose: 3-O-methyl-D-glucose ratio was higher in the trauma group at all time points. Significant correlation was found between severity of trauma and xylose and 3-O-methyl-D-glucose recoveries 24 hours after injury. Results of this study support the hypothesis that intestinal permeability and absorption are altered in dogs with traumatic injury.