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  • Author or Editor: Rebecca L. Hegstad x
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SUMMARY

A commercially available radioimmunoassay (ria) kit for measurement of human adrenocorticotropin (hacth) was validated for use in dogs. Assay sensitivity was 3 pg/ ml. Intra-assay coefficient of variation (× 100; cv) for 3 canine plasma pools was 3.0 (mean ± sd, 33 ± 0.99 pg/ ml), 4.2 (71 ± 2.4 pg/ml) and 3.7 (145 ± 3.7 pg/ml) %. Interassay cv for 2 plasma pools measured in 6 assays was 9.8 (37 ± 3.6 pg/ml) and 4.4 (76 ± 3.4 pg/ml) %, respectively. Dilutional parallelism was documented by assaying 2 pools of canine plasma at 3 dilutions and correcting the measured result for dilution. Corrected mean concentrations for the first pool were 33 (± 0.99), 36 (± 4.3), and 33 (± 6.8) pg/ml; corrected mean concentrations for the second pool were 145 (± 5.4), 141 (± 10.8) and 125 (± 3.4) pg/ml. Recovery of 1-39hacth added to canine plasma (6.25, 12.5, 25.0, 50.0, and 100.0 pg/ml) was linear and quantitative (slope = 0.890, R 2 = 0.961). To test whether anticoagulant or the protease inhibitor, aprotinin, influences acth concentration in canine plasma, acth was measured in canine blood collected in 4 tubes containing anticoagulant: heparin (h), heparin + 500 kallikrein inhibitor units (KIU) of aprotinin/ml (ha), edta (e), and edta + aprotinin (ea). Plasma acth concentration was the same when samples containing h and ha, or ha and e were compared, and was significantly (P < 0.01) lower in samples containing ea. Plasma storage at - 20 C for 1 week or 1 month was not associated with significant change in acth concentration in canine plasma, using any of the 4 anticoagulant treatments. Plasma acth concentration measured after 6 months’ storage at —20 C was significantly (P < 0.01) lower for all anticoagulants used. Synthetic 1-39hacth added to canine blood was accurately recovered (88 to 109%, n = 3) from plasma containing edta, with or without aprotinin, whereas percentage recovery was overestimated by 18 to 91% in heparinized plasma. Plasma acth concentrations in edta- treated canine blood kept at 4 or 22 to 25 C for 15 to 90 minutes prior to centrifugation at 8 C were not significantly different. Plasma acth concentration in canine plasma was affected by storage tube material. Concentration of acth in canine plasma stored in borosilicate glass tubes for 1 week or 1 month at — 70 C was significantly higher than initial acth values (P ≤ 0.01), but was unchanged over time in plasma stored in polypro-pylene or polystyrene tubes.

Sample handling procedures affect canine plasma acth concentration measured by use of the ria kit. Optimal sample handling conditions for plasma acth measurement in dogs include use of edta anticoagulant, blood collected at 20 to 25 C (room temperature) followed by centrifugation within 15 to 90 minutes, and plasma storage in plastic (not glass) tubes for not longer than 1 month at −20 C.

Free access
in American Journal of Veterinary Research

Abstract

Objective—To determine whether dogs with renal failure have higher serum cardiac troponin I (cTnI) concentrations than healthy dogs.

Design—Case-control study.

Animals—31 dogs with renal failure and 51 healthy dogs.

Procedures—Serum concentrations of creatinine and cardiac troponin I, urine specific gravity, and systolic arterial blood pressure were measured for all dogs. Dogs underwent a standardized physical examination, and any dog with evidence of cardiovascular disease or other nonrenal disease was excluded from final analyses. Dogs were considered to be in renal failure when the serum creatinine concentration was ≥ 3.0 mg/dL, urine specific gravity was between 1.007 and 1.030, and renal failure had been clinically diagnosed.

Results—Dogs with renal failure had significantly higher serum cTnI concentrations (median, 0.35 ng/mL) than did healthy dogs (0.20 ng/mL). The renal failure group also had a significantly higher median systolic blood pressure (156 mm Hg) than did healthy dogs (138 mm Hg), although serum cTnI concentration was not correlated with systolic blood pressure in dogs with renal failure. There was no significant difference in age between dogs with renal failure and healthy dogs, but dogs with renal failure had significantly higher serum creatinine concentration and lower urine specific gravity.

Conclusions and Clinical Relevance—Although dogs with renal failure did not have overt clinical signs of cardiac disease, they had high serum cTnI concentrations, which may have been associated with subclinical cardiovascular disease. The cause of the high serum cTnI concentration in these dogs requires additional investigation.

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective

To determine whether alterations in carbohydrate metabolism exist in dogs with nonhematopoietic malignancies but without evidence of weight loss or cachexia.

Animals

90 dogs with nonhematopoietic malignancies and 18 control dogs.

Procedure

An intravenous glucose tolerance test was done in 90 dogs with previously untreated nonhematopoietic malignancies and in 18 clinically normal dogs. These dogs also had no evidence of unrelated diseases that would affect glucose metabolism. None of the dogs had evidence of cachexia. Samples were assayed for glucose, lactate, and insulin concentrations. This procedure was repeated for 45 of the tumor-bearing dogs from which all gross evidence of tumor was completely excised and evidence of diseases that would alter carbohydrate metabolism did not exist.

Results

The mean of all time points during the intravenous glucose tolerance test (ie, 0, 5, 15, 30, 45, and 60 minutes) for lactate (12.9 ± 6.7 mg/dl) and insulin (69.1 ± 44.9 µU/ml) concentrations in untreated dogs with nonhematopoietic malignancies were significantly higher than values for controls (lactate, 9.7 ± 4.3 mg/dl; and insulin, 31.7 ± 11.5 µU/ml). This increase in lactate and insulin values did not return to normal when the dogs were rendered free of all observable evidence of cancer after surgery.

Conclusions

Carbohydrate metabolism is altered in dogs with a variety of nonhematopoietic malignancies and these abnormalities do not abate when dogs are rendered free of gross evidence of malignant disease after surgery.

Clinical Relevance

Alterations in carbohydrate metabolism may result in decreased quality of life and may be associated with the paraneoplastic syndrome, cancer cachexia. (Am J Vet Res 1997;58:277–281)

Free access
in American Journal of Veterinary Research

Summary

A commercially available radioimmunoassay kit for measurement of human osteocalcin was validated for use in horses. For accurate measurement of equine serum osteocalcin, blood samples may be collected at a temperature between 20 and 25 C, then centrifuged within 90 minutes; serum may be stored at —20 C in plastic tubes for up to 26 weeks. Serum may be thawed and refrozen up to 5 times without significant change in measured equine serum osteocalcin concentration. Assay sensitivity was 0.16 ng/ml. Recovery of bovine osteocalcin standard added to equine serum was linear. Intra-assay coefficient of variation (X 100) for 2 equine serum pools was 6.9 (mean ± SD, 13.9 ± 1.0 ng/ml) and 7.5 (10.6 ± 0.8 ng/ml) %. Interassay coefficient of variation for 3 equine serum pools measured in 12 assays was 12.5 (16.1 ± 2.0 ng/ml), 12.7 (11.5 ± 1.5 ng/ml), and 24.6 (3.0 ± 0.7 ng/ml) %. Dilutional parallelism was documented by assaying pooled equine serum at 4 dilutions and correcting the mean result for dilution. Significant change was not observed in equine serum osteocalcin concentration for various time-of-day blood sample collections in horses housed under continuous lighting.

Free access
in American Journal of Veterinary Research

Summary

Luteinizing hormone (lh) and acth concentrations were measured in plasma from 7 cows to determine whether acth secretion changes with the phase of the estrous cycle, and to determine whether any acth peaks are associated with lh peaks. Blood was collected every 5 minutes for 190 minutes during the luteal and follicular phases of the estrous cycle. Radioimmunoassays were used to measure acth and lh in plasma. Mean concentration of acth in all cows did not differ significantly between luteal (35.1 ± 8.0 pg/ml) and follicular (37.5 ± 9.4 pg/ml) phases of the estrous cycle. Mean concentration of luteal-phase lh of all cows (2.0 ± 1.1 ng/ml) was significantly (P < 0.01) lower than mean concentration of follicular-phase lh (5.4 ± 1.6 ng/ml). Frequency of peaks in acth concentration was low during the sampling period. Mean number of luteal-phase acth peaks (0.29 ± 0.49) was not significantly different from that of follicular-phase samples (0.43 ± 0.53). Unlike acth, mean frequency of lh peaks was significantly (P < 0.05) higher in plasma from cows in the follicular phase of the estrous cycle (2.9 ± 0.7), compared with that from cows in the luteal phase (0.29 ± 0.49).

Free access
in American Journal of Veterinary Research

Abstract

Objective—To determine the effects of hypothyroidism on insulin sensitivity, glucose tolerance, and concentrations of hormones counter-regulatory to insulin in dogs.

Animals—8 anestrous mixed-breed bitches with experimentally induced hypothyroidism and 8 euthyroid control dogs.

Procedures—The insulin-modified frequently sampled IV glucose tolerance test and minimal model analysis were used to determine basal plasma insulin and glucose concentrations, acute insulin response to glucose, insulin sensitivity, glucose effectiveness, and disposition index. Growth hormone response was assessed by stimulation and suppression tests. Additionally, basal serum growth hormone (GH) and insulin-like growth factor-1 (IGF-1) concentrations and urine cortisol-to-creatinine concentration ratios were measured and dual energy x-ray absorptiometry was performed to evaluate body composition.

Results—Insulin sensitivity was lower in the hypothyroid group than in the euthyroid group, whereas acute insulin response to glucose was higher. Glucose effectiveness and disposition index were not different between groups. Basal serum GH and IGF-1 concentrations as well as abdominal fat content were high in hypothyroid dogs, but urine cortisol-to-creatinine concentration ratios were unchanged.

Conclusions and Clinical Relevance—Hypothyroidism appeared to negatively affect glucose homeostasis by inducing insulin resistance, but overall glucose tolerance was maintained by increased insulin secretion in hypothyroid dogs. Possible factors affecting insulin sensitivity are high serum GH and IGF-1 concentrations and an increase in abdominal fat. In dogs with diseases involving impaired insulin secretion such as diabetes mellitus, concurrent hypothyroidism can have important clinical implications.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate and compare circulating concentrations of islet amyloid polypeptide (IAPP), insulin, and glucose in nondiabetic cats classified by body condition score (BCS) and in cats with naturally occurring diabetes mellitus.

Animals—109 (82 nondiabetic, 21 nonketoacidotic diabetic, and 6 ketoacidotic diabetic) cats.

Procedures—Cats were examined and BCSs were assessed on a scale of 1 to 9. After food was withheld for 12 hours, blood was collected and plasma concentrations of IAPP and serum concentrations of insulin and glucose were measured. Differences in these values were evaluated among nondiabetic cats grouped according to BCS and in diabetic cats grouped as ketoacidotic or nonketoacidotic on the basis of clinicopathologic findings. Correlations were determined among variables.

Results—In nondiabetic cats, BCS was significantly and positively correlated with circulating IAPP and insulin concentrations. Mean plasma IAPP concentrations were significantly different between cats with BCSs of 5 and 7, and mean serum insulin concentrations were significantly different between cats with BCSs of 5 and 8. Serum glucose concentrations were not significantly different among nondiabetic cats. Mean IAPP concentrations were similar between nonketoacidotic diabetic cats and nondiabetic cats with BCSs of 8 or 9. Mean IAPP concentrations were significantly reduced in ketoacidotic diabetic cats, compared with those of nondiabetic cats with BCSs of 6 through 8 and of nonketoacidotic diabetic cats.

Conclusions and Clinical Relevance—Results indicated that increased BCS (a measure of obesity) is associated with increased circulating concentrations of IAPP and insulin in nondiabetic cats.

Full access
in American Journal of Veterinary Research

SUMMARY

Eighteen dogs undergoing lateral thoracotomy at the left fifth intercostal space were randomly assigned to 1 of 3 postoperative analgesic treatment groups of 6 dogs each as follows: group A, morphine, 1.0 mg/kg of body weight, im; group B, 0.5% bupivacaine, 1.5 mg/kg given interpleurally; and group C, morphine, 1.0 mg/kg given interpleurally. Heart rate, respiratory rate, arterial blood pressure, arterial blood gas tensions, alveolar-arterial oxygen differences, rectal temperature, pain score, and pulmonary mechanics were recorded hourly for the first 8 hours after surgery, and at postoperative hours 12, 24, and 48. These values were compared with preoperative (control) values for each dog. Serum morphine and cortisol concentrations were measured at 10, 20, and 30 minutes, hours 1 to 8, and 12 hours after treatment administration.

All dogs had significant decreases in pHa, PaO2 , and oxygen saturation of hemoglobin, and significant increases in PaCO2 and alveolar-arterial oxygen differences in the postoperative period, but these changes were less severe in group-B dogs. Decreases of 50% in lung compliance, and increases of 100 to 200% in work of breathing and of 185 to 383% in pulmonary resistance were observed in all dogs after surgery. Increases in work of breathing were lower, and returned to preoperative values earlier in group-B dogs. The inspiratory time-to-total respiratory time ratio was significantly higher in group-B dogs during post-operative hours 5 to 8, suggesting improved analgesia. Blood pressure was significantly lower in group-A dogs for the first postoperative hour. Significant decreases in rectal temperature were observed in all dogs after surgery, and hypothermia was prolonged in dogs of groups A and C. Significant differences in pain score were not observed between treatment groups. Cortisol concentration was high in all dogs after anesthesia and surgery, and was significantly increased in group-B dogs at hours 4 and 8. Significant differences in serum morphine concentration between groups A and C were only observed 10 minutes after treatment administration. In general, significant differences in physiologic variables between groups A and C were not observed.

Results of the study indicate that anesthesia and thoracotomy are associated with significant alterations in pulmonary function and lung mechanics. Interpleurally administered bupivacaine appears to be associated with fewer blood gas alterations and earlier return to normal of certain pulmonary function values. Interpleural administration of morphine does not appear to provide any advantages, in terms of analgesia or pulmonary function, compared with its im administration.

Free access
in American Journal of Veterinary Research