Introduction

Recognition of clinical and laboratory features that prompt ACTH stimulation testing in dogs with hypoadrenocorticism (hypoA) may speed diagnosis of this potentially life-threatening condition. This retrospective study evaluates hypoalbuminaemia as a potential marker of hypoA in dogs.

Materials and Methods

Medical records of 66 dogs diagnosed with hypoA by an inadequate response to ACTH stimulation testing, were studied from two referral clinics (1998-2006); Davies Veterinary Specialists (D) and The Royal Veterinary College (R). Dogs were classified as having primary (n=49), atypical (n=15) or secondary (n=2) hypoadrenocorticism. Serum albumin concentrations were analysed in subgroups (D-1, R-2, R-3, R-4) because different laboratories and reference ranges were used. A control population of healthy dogs (n=92) was recruited for comparison with the RVC cases (R-2C and R-3C).

Results

More hypoA dogs had low albumin than controls [39.4% vs 5.4%; Chi-square 25.9, p<0.0005]. Hypoalbuminaemia was more common in atypical hypoA (80%) compared with primary hypoA (28.6%) and normal dogs (5.4%) (Chi-square 48.4, p<0.0005). Albumin concentrations (g/l) from atypical hypoA dogs (R-2; 24.6±3.4, R-3; 20.4±3.2) were consistently lower than controls (R-2C; 32.6±3.1, R-3C; 35.5±3.6). While more primary hypoA dogs had low albumin than controls they also had a wider variation in albumin concentrations (R-2; 27±5.7, R-3; 31.3±6.9) than the atypical group leading to less consistent changes. Raised creatinine levels suggesting pre-renal azotaemia consistent with dehydration were seen more commonly in the primary hypoA group. There were significant increases in albumin concentrations after treatment for hypoA in D-1 (p=0.023) and R-2 (p=0.03) but not in R-3 (p=0.122) groups. (Significance level p<0.05)

Conclusions

This study shows that hypoalbuminaemia is common in hypoA dogs, especially those with atypical hypoA and suggests that ACTH stimulation testing should be considered in dogs presenting with persistent mild hypoalbuminaemia and vague clinical signs.