Abstract
Fasting hypertriglyceridaemia can occur as a primary disorder or secondary to underlying diseases such as hyperadrenocorticism, diabetes mellitus and hypothyroidism. Primary hypertriglyceridaemia in Miniature Schnauzers has a reported prevalence of approximately 30% in North America, increasing with age. Data on the prevalence of primary and secondary hypertriglyceridaemia in other countries are lacking. The aim of this study was to investigate the prevalence and causes of fasting hypertriglyceridaemia in Australian Miniature Schnauzers.
Two hundred and fifteen healthy Miniature Schnauzers were recruited into a cross-sectional study. Each dog was assessed with an owner questionnaire and a physical examination. Triglyceride concentrations were measured after a 15-hour fast. If fasting hypertriglyceridemia was identified, haematology, serum biochemistry, urinalysis (including urine protein:creatinine ratio), total thyroxine (including thyroid stimulating hormone if total thyroxine was low) and a low-dose dexamethasone suppression test were performed. Dogs with no underlying cause for the fasting hypertriglyceridemia had an adrenocorticotrophic hormone stimulation test. Thirty dogs with normal triglyceride concentrations underwent the same testing to act as controls.
Forty of 215 dogs (18.6%; 95% CI: 14.0%-24.3%) had fasting hypertriglyceridemia. The prevalence of fasting hypertriglyceridaemia increased with age; 0%, 9%, 11%, 26% and 64% in dogs <1 year,1-3 years, 4-6 years, 7-9 years and >9 years, respectively. Thirty-nine hypertriglyceridaemic dogs underwent further testing and 31 (79.4%; 95% CI: 63.5%-90.7%) had hyperadrenocorticism, one (2.5%; 95% CI: 0%-13.4%) had hypothyroidism and seven (17.9%; 95% CI: 7.5%-33.5%) had primary hypertriglyceridemia. Ten of the 30 control dogs (33.3%; 95% CI: 17.2%-52.8%) were diagnosed with hyperadrenocorticism. No other diseases were identified in the control group. Fasting hypertriglyceridaemia was significantly associated with secondary disease (P<0.001) with a relative risk of 2.4 (CI 1.4-4.1).
The estimated prevalence of fasting hypertriglyceridaemia in Australian Miniature Schnauzers was lower than in North America. Primary hypertriglyceridaemia was uncommon in this study, with the majority of affected dogs being diagnosed with hyperadrenocorticism. Thorough investigation of hyperadrenocorticism and other secondary causes should be undertaken when fasting hypertriglyceridaemia is identified in Miniature Schnauzers.