Patient signalment and pathological causes of canine hyperadrenocorticism have been largely derived from studies on North American dog populations. It is has been suggested that these findings are not necessarily applicable to other countries.

This retrospective study assessed 200 consecutive records of Australian dogs between 2006–2009 that had samples submitted to an accredited laboratory for measurement of endogenous adrenocorticotropic hormone (ACTH) by radioimmunoassay. Adrenal ultrasonography was not easily available for most general veterinary practices at this time and the endogenous ACTH assay was routinely used for differentiation of pituitary from adrenal dependent disease. Clinical and clinicopathologic data were obtained from the laboratory submissions and/or submitting practitioner patient records. A total of 175 dogs met the inclusion criteria for a confirmed diagnosis of hyperadrenocorticism. This subset was evaluated for age, body weight, sex, breed and lesion location (pituitary versus adrenal).

Median age of the assessed dogs was 11 years and median body weight was 8.17 kg. Sixty-one percent of the dogs were female and 39% male. The most commonly affected breeds were crossbred dogs (32.6%) and Maltese (20.6%). Maltese crossbreds and Maltese purebreds together comprised 31.4% of the study population. Other commonly identified breeds included Australian Cattle Dog, Jack Russell Terrier (3.4% each), Poodle, Miniature Fox Terrier, Shi Tzu and Bichon Frise (2.9% each). Pituitary dependent hyperadrenocorticism was identified in 171 dogs (97.7%). A functional adrenal tumour was found in 3 dogs (1.7%) and suspected in a fourth dog.

The results demonstrated that Australian dogs with hyperadrenocorticism have a lower median body weight and a higher prevalence of pituitary dependent disease when compared to the North American data. In addition a striking percentage of the study population were Maltese dogs and their crosses. These findings have implications for investigation and therapy of canine hyperadrenocorticism in Australia. They also highlight that regional differences in hyperadrenocorticism should be recognised by veterinarians worldwide.

Disclosures

Disclosures to report:

This study was a population study and involved no conflict of interest by the authors. One of the authors (BD) is employed by the accredited laboratory that was the source of the raw data. One of the authors (SF) is a consultant to the same laboratory. The study was an independent collaborative retrospective study. It was not performed for any commercial benefit and was not funded by any person or entity.