Rodolfo Oliveira Leal

Background Dogs with eunatremic, eukalemic hypoadrenocorticism (EEH) typically show signs of chronic gastrointestinal disease (CGD). Previous glucocorticoid administration (PGA) can give false‐positive results on the ACTH stimulation test (ACTHst). Hypothesis/Objectives To determine the prevalence of EEH in dogs with signs of CGD, and to identify clinical and clinicopathological features for EEH and PGA. Animals One hundred twelve dogs with CGD (101 non‐PGA and 11 PGA), 20 dogs with EEH. Methods Multicenter prospective cohort study. Basal serum cortisol (BSC) concentration was measured in dogs with signs of CGD. When BSC was <2 μg/dL and in PGA dogs, ACTHst plus measurement of endogenous ACTH (eACTH) were performed. Records of dogs with EEH from 2009 to 2021 were reviewed. Results The BSC concentration was <2 μg/dL in 48/101 (47.5%) non‐PGA and in 9/11 (82%) PGA dogs. EEH was diagnosed in 1/112 dog (prevalence 0.9%; 95% CI, 0.1%‐4.8%); the ACTHst provided false‐positive results in 2/11 PGA dogs. PGA dogs showed lower C‐reactive protein‐to‐haptoglobin ratio (median 0.01, range 0.003‐0.08; P = .01), and higher haptoglobin (140, 26‐285 mg/dL; P = .002) than non‐PGA dogs (0.04, 0.007‐1.5; 38.5, 1‐246 mg/dL, respectively). eACTH was higher ( P = .03) in EEH (396, 5‐>1250 pg/mL) than in non‐PGA dogs (13.5, 7.3‐46.6 pg/mL). Cortisol‐to‐ACTH ratio was lower ( P < .0001 and P = .01, respectively) in EEH (0.002, 0.0002‐0.2) than in non‐PGA (0.1, 0.02‐0.2) and PGA dogs (0.1, 0.02‐0.2). Conclusions and Clinical Importance The prevalence of EEH in dogs with signs of CGD was lower than previously reported. The clinical and clinicopathological features herein identified could increase the index of suspicion for EEH or PGA in dogs with an unclear history of glucocorticoid administration.

Background Pheochromocytoma (PCC) is rare in cats and plasma (PL) and urinary (U) metanephrines (metanephrine [MN]; normetanephrine [NMN]) measurement is rarely described in cats. Objectives We evaluated the utility of PL and U MNs measurement in 10 healthy cats and a cat with a confirmed diagnosis of pheochromocytoma (PheoCat), using liquid chromatography with tandem mass spectrometry (LC‐MS‐MS). Methods Urine and EDTA PL samples collected from each of the 10 cats and the PheoCat were promptly stored at −80°C and remained frozen until analysis. To evaluate U MNs stability, an additional urine sample collected from the healthy cats was refrigerated for 24 hours before freezing. Urinary creatinine concentration (Creat) was assessed using the same spot urine samples to calculate U MNs‐to‐creatinine ratios. Results The PL‐MN and PL‐NMN median concentrations of the healthy cats were 2.73 and 7.02 nmol/L, respectively. The median U‐MN/Creat and U‐NMN/Creat ratios were 70 and 139 μg/g, respectively. The PheoCat had a PL‐MN of 3.68 nmol/L, PL‐NMN of 66.27 nmol/L, U‐MN/Creat of 179 μg/g, and U‐NMN/Creat of 1262 μg/g. The PheoCat had markedly increased concentrations of both PL and U MNs when compared to the healthy cats. No significant difference was found between U MNs measured in urine samples that underwent 24 hours of refrigeration in comparison to those that were frozen immediately. Conclusions We report preliminary reference intervals for PL and U MNs in cats using LC‐MS‐MS and the potential clinical applicability of these biomarkers for the diagnosis of PCC in cats.