Peter H. Kook

Urinary catecholamine and metanephrine to creatinine ratios in healthy dogs at home and in a hospital environment and in 2 dogs with pheochromocytoma

BACKGROUND Measurement of high concentrations of urine catecholamines and metanephrines is useful in diagnosing pheochromocytoma in humans. Stress increases catecholamine excretion in urine. HYPOTHESIS Stress of a hospital visit increases urinary catecholamine and metanephrine excretion in dogs. ANIMALS Fourteen clinically normal dogs, 2 dogs with pheochromocytoma. METHODS Voided urine samples were collected by the owners 7 days before (t-7), during the hospital visit immediately after diagnostic procedures (t0), as well as 1 (t1) and 7 days (t7) after the hospital visit. Urine catecholamine and metanephrine concentrations were measured using high-pressure liquid chromatography and expressed as ratios to urine creatinine concentration. RESULTS In client-owned dogs epinephrine and norepinephrine ratios at t0 were significantly higher compared with ratios at t7. Metanephrine and normetanephrine ratios at t-7, t0, and t1 did not differ significantly from each other; however, at t7 they were significantly lower compared to values at t-7. In staff-owned dogs no significant differences were detected among the different collecting time points for any variable. Metanephrine and normetanephrine ratios were significantly higher in client-owned dogs compared to staff-owned dogs at t-7, t0, and t1 but not at t7. CONCLUSIONS AND CLINICAL IMPORTANCE Stress associated with a hospital visit and with the sampling procedure causes increases in urine catecholamine and metanephrine excretion. Urine collection for the diagnosis of pheochromocytoma probably should take place at home after adaptation to the sampling procedure.

Urinary catecholamine and metanephrine to creatinine ratios in dogs with hyperadrenocorticism or pheochromocytoma, and in healthy dogs.

BACKGROUND Urinary catecholamines and metanephrines are used for the diagnosis of pheochromocytoma (PHEO) in dogs. Hyperadrenocorticism (HAC) is an important differential diagnosis for PHEO. OBJECTIVES To measure urinary catecholamines and metanephrines in dogs with HAC. ANIMALS Fourteen dogs with HAC, 7 dogs with PHEO, and 10 healthy dogs. METHODS Prospective clinical trial. Urine was collected during initial work-up in the hospital; in dogs with HAC an additional sample was taken at home 1 week after discharge. Parameters were measured using high-pressure liquid chromatography and expressed as ratios to urinary creatinine concentration. RESULTS Dogs with HAC had significantly higher urinary epinephrine, norepinephrine and normetanephrine to creatinine ratios than healthy dogs. Urinary epinephrine, norepinephrine, and metanephrine to creatinine ratios did not differ between dogs with HAC and dogs with PHEO, whereas the urinary normetanephrine to creatinine ratio was significantly higher (P= .011) in dogs with PHEO (414, 157.0-925.0, median, range versus (117.5, 53.0-323.0). Using a cut-off ratio of 4 times the highest normetanephrine to creatinine ratio measured in controls, there was no overlap between dogs with HAC and dogs with PHEO. The variables determined in urine samples collected at home did not differ from those collected in the hospital. CONCLUSION AND CLINICAL IMPORTANCE Dogs with HAC might have increased concentrations of urinary catecholamines and normetanephrine. A high concentration of urinary normetanephrine (4 times normal), is highly suggestive of PHEO.

Ultrasonographic evaluation of adrenal glands in dogs with primary hypoadrenocorticism or mimicking diseases

The adrenal glands of 30 dogs with primary adrenal insufficiency (hypoadrenocorticism) were measured ultrasonographically and compared with those of 14 healthy dogs and those of 10 dogs with diseases mimicking hypoadrenocorticism. Thickness and length of the adrenals were measured on abdominal ultrasonography and the results for each group were compared. Dogs with primary hypoadrenocorticism had significantly thinner adrenals compared with the other two groups, and their left adrenal glands were also significantly shorter than those of healthy dogs. Adrenal ultrasonography may be of diagnostic value in dogs with clinical signs suggestive of primary hypoadrenocorticism, as a left adrenal gland measuring less than 3.2 mm in thickness is strongly suggestive of the disease.

Urinary catecholamine and metadrenaline to creatinine ratios in dogs with a phaeochromocytoma.

Urinary adrenaline (epinephrine), noradrenaline, dopamine, metadrenaline (metanephrine) and normetadrenaline to creatinine ratios were measured from spot samples of seven client-owned dogs with a histologically confirmed phaeochromocytoma. Urine was collected on day 0 in the hospital in six dogs, and additionally on days 2, 6 and 7 after discharge in two of these dogs. In one dog, urine was sampled on day 7 only. Samples were also collected from 10 healthy control dogs on days 0, 1 and 7. In dogs with phaeochromocytomas, normetadrenaline:creatinine ratios at all time points ranged from 103 to 6430 nmol/mmol. From day 0, ratios of samples taken at the hospital (range 157 to 925 nmol/mmol) were significantly higher (P<0.0012) compared with control samples (range 14 to 91 nmol/mmol). The highest normetadrenaline:creatinine ratios were found in two dogs with bilateral phaeochromocytomas. Adrenaline:creatinine and noradrenaline:creatinine ratios were also significantly increased (P<0.016) in dogs with a phaeochromocytoma at day 0 compared with controls, although the difference was less pronounced than that between controls and dogs with a phaeochromocytoma for the normetadrenaline:creatinine ratio. Urine normetadrenaline:creatinine ratios may be useful in the diagnosis of canine phaeochromocytomas.

Microbiologic evaluation of gallbladder bile of healthy dogs and dogs with iatrogenic hypercortisolism: a pilot study.

BACKGROUND In people, hypercortisolism (HC) has been associated with acalculous cholecystitis and biliary dyskinesia, which may potentiate ascending biliary infections. In dogs, an association between HC and gallbladder disease recently has been documented, although the role of bacteria remains controversial. Furthermore, there is no information on the gallbladder bile microbial flora in healthy dogs. OBJECTIVES To investigate the microbial flora in gallbladder bile in healthy dogs, the relationship between iatrogenic hyperadrenocorticism and bactibilia and possible changes in biliary microbial flora after cortisol withdrawal in dogs. ANIMALS Six control dogs and 6 dogs treated with hydrocortisone. METHODS Gallbladder bile obtained by percutaneous ultrasound-guided cholecystocentesis was cultured aerobically and anaerobically and examined cytologically before (d0), during (d28, d56, d84), and after (d28p, d56p, d84p) administration of hydrocortisone (8 mg/kg PO q12h). RESULTS In the control group, 2/42 bile cultures yielded bacterial growth (Enterococcus sp.; Escherichia coli on d0) and 1/42 bile smears had cytological evidence of bacteria (d28). In the HC group, 2/42 bile cultures yielded bacterial growth (Enterococcus sp. on d28; Bacillus sp. on d28p) and 3/42 bile smears had cytological evidence of bacteria (d84, d84, d28p). All dogs remained healthy throughout the study period (168d). CONCLUSIONS AND CLINICAL IMPORTANCE Based on the results of conventional bacterial culture techniques, gallbladder bile of healthy dogs periodically may harbor bacteria, which do not appear to be clinically relevant. A 3-month period of iatrogenic HC was not associated with bactibilia. A higher prevalence of bactibilia may be detected with micromolecular techniques.

A frameshift mutation in the cubilin gene (CUBN) in Border Collies with Imerslund-Grasbeck syndrome (selective cobalamin malabsorption).

Imerslund-Gräsbeck syndrome (IGS) or selective cobalamin malabsorption has been described in humans and dogs. IGS occurs in Border Collies and is inherited as a monogenic autosomal recessive trait in this breed. Using 7 IGS cases and 7 non-affected controls we mapped the causative mutation by genome-wide association and homozygosity mapping to a 3.53 Mb interval on chromosome 2. We re-sequenced the genome of one affected dog at ∼10× coverage and detected 17 non-synonymous variants in the critical interval. Two of these non-synonymous variants were in the cubilin gene (CUBN), which is known to play an essential role in cobalamin uptake from the ileum. We tested these two CUBN variants for association with IGS in larger cohorts of dogs and found that only one of them was perfectly associated with the phenotype. This variant, a single base pair deletion (c.8392delC), is predicted to cause a frameshift and premature stop codon in the CUBN gene. The resulting mutant open reading frame is 821 codons shorter than the wildtype open reading frame (p.Q2798Rfs*3). Interestingly, we observed an additional nonsense mutation in the MRC1 gene encoding the mannose receptor, C type 1, which was in perfect linkage disequilibrium with the CUBN frameshift mutation. Based on our genetic data and the known role of CUBN for cobalamin uptake we conclude that the identified CUBN frameshift mutation is most likely causative for IGS in Border Collies.

Agreement of Serum Spec cPL with the 1,2-o-Dilauryl-Rac-Glycero Glutaric Acid-(6′-methylresorufin) Ester (DGGR) Lipase Assay and with Pancreatic Ultrasonography in Dogs with Suspected Pancreatitis

Background Spec cPL is the most sensitive and specific test for diagnosing pancreatitis in dogs. Its results have not been compared to those of the 1,2‐o‐dilauryl‐rac‐glycero‐3‐glutaric acid‐(6′‐methylresorufin) ester (DGGR) lipase assay or those of abdominal ultrasonography. Objectives To investigate agreement of Spec cPL with DGGR lipase activity and pancreatic ultrasonography in dogs with suspected pancreatitis. Animals One hundred and forty‐two dogs. Methods DGGR lipase activity (reference range, 24–108 U/L) and Spec cPL were measured using the same sample. The time interval between ultrasonography and lipase determinations was <24 hours. The agreement of the 2 lipase assays at different cutoffs and the agreement between pancreatic ultrasonography and the 2 tests were assessed using Cohens kappa coefficient (κ). Results DGGR lipase (>108, >216 U/L) and Spec cPL (>200 μg/L) had κ values of 0.79 (95% confidence interval [CI], 0.69–0.9) and 0.70 (CI, 0.58–0.82). DGGR lipase (>108, >216 U/L) and Spec cPL (>400 μg/L) had κ values of 0.55 (CI, 0.43–0.67) and κ of 0.80 (CI, 0.71–0.9). An ultrasonographic diagnosis of pancreatitis and DGGR lipase (>108, >216 U/L) had κ values of 0.29 (CI, 0.14–0.44) and 0.35 (CI, 0.18–0.52). Ultrasonographically diagnosed pancreatitis and Spec cPL (>200, >400 μg/L) had κ values of 0.25 (CI, 0.08–0.41) and 0.27 (CI, 0.09–0.45). Conclusions and Clinical Importance Although both lipase assays showed high agreement, agreement between ultrasonography and lipase assays results was only fair. Because lipase results are deemed more accurate, ultrasonography results should be interpreted carefully.

The effect of orally administered ranitidine and once-daily or twice-daily orally administered omeprazole on intragastric pH in cats.

Background Gastric acid suppressants frequently are used in cats with acid‐related gastric disorders. However, it is not known if these drugs effectively increase intragastric pH in cats. Objectives To examine the effects of PO administered ranitidine and omeprazole on intragastric pH in cats and to compare the efficacy of once‐daily versus twice‐daily dosage regimens for omeprazole. Animals Eight domestic shorthair cats. Methods Using a randomized 4‐way cross‐over design, cats were given enteric‐coated omeprazole granules (1.1–1.3 mg/kg q24h and q12h), ranitidine (1.5–2.3 mg/kg q12h), and placebo. Intragastric pH was monitored continuously for 96 hours using the Bravo™ system1, starting on day 4 of treatment, followed by a median washout period of 12 days. Mean percentage of time pH was ≥3 and ≥4 was compared among groups using repeated measures ANOVA. Results Mean ± SD percentage of time intragastric pH was ≥3 and ≥4 was 67.0 ± 24.0% and 54.6 ± 26.4% for twice‐daily omeprazole, 24.4 ± 22.8% and 16.8 ± 19.3% for once‐daily omeprazole, 16.5 ± 9.0% and 9.6 ± 5.9% for ranitidine, and 9.4 ± 8.0% and 7.0 ± 6.6% for placebo administration. Twice‐daily omeprazole treatment significantly increased intragastric pH, whereas pH after once‐daily omeprazole and ranitidine treatments did not differ from that of placebo‐treated cats. Conclusion and Clinical Importance Only twice‐daily PO administered omeprazole significantly suppressed gastric acidity in healthy cats, whereas once‐daily omeprazole and standard dosages of ranitidine were not effective acid suppressants in cats.

Clinical and Laboratory Findings in Border Collies with Presumed Hereditary Juvenile Cobalamin Deficiency

Juvenile cobalamin deficiency is a rare disease in border collies and its diagnosis requires a high level of clinical suspicion. The goal of this study was to increase awareness of this disease by describing the clinical and laboratory findings in four young border collies with inherited cobalamin deficiency. The median age of the dogs was 11.5 mo (range, 8-42 mo), and two of the four dogs were full siblings. Clinical signs included intermittent lethargy (n = 4), poor body condition (n = 4), odynophagia (n = 2), glossitis (n = 1), and bradyarrhythmia (n = 1). Pertinent laboratory abnormalities were mild to moderate normocytic nonregenerative anemia (n = 3), increased aspartate aminotransferase (AST) activity (n = 3), and mild proteinuria (n = 3). All of the dogs had serum cobalamin levels below the detection limit of the assay, marked methylmalonic aciduria, and hyperhomocysteinemia. Full clinical recovery was achieved in all dogs with regular parenteral cobalamin supplementation, and laboratory abnormalities resolved, except the proteinuria and elevated AST activity persisted. This case series demonstrates the diverse clinical picture of primary cobalamin deficiency in border collies. Young border collies presenting with ambiguous clinical signs should be screened for cobalamin deficiency.

Hyperglycaemia but not hyperlipidaemia decreases serum amylase and increases neutrophils in the exocrine pancreas of cats.

The goal of the study was to determine whether hyperglycaemia or hyperlipidaemia causes pancreatitis in cats and to assess the effect of excess serum glucose and lipids on amylase and lipase activity. Ten-day hyperglycaemic and hyperlipidaemic clamps were carried out in five and six healthy cats, respectively. Ten healthy cats received saline and served as controls. The activity of amylase was below the normal range in 4 of 5 hyperglycaemic cats by day 10. The activity of lipase did not vary in any of the cats. Samples of exocrine pancreas were normal on histological examination, but the number of tissue neutrophils was increased in hyperglycaemic cats (P<0.05). In a retrospective study 14 of 40 (35%) cats with naturally occurring diabetes mellitus had amylase activities below the reference range at the time of admission. Amylase activities normalised within 1 week of insulin therapy and subsequent glycaemic control. Lipase activity was increased in 26 of 40 (65%) diabetic cats and remained elevated despite glycaemic control. In conclusion, hyperglycaemia, but not hyperlipidaemia, increases pancreatic neutrophils in cats. However, because the histological morphology of the exocrine pancreas was normal, hyperglycaemia may play only a minor role in the pathogenesis of pancreatitis. Low amylase activities in diabetic cats may reflect an imbalance in glucose metabolism rather than pancreatitis.