Association of aldosterone and arginine vasopressin concentrations and clinical markers of hypoperfusion in neonatal foals.

The research investigates the link between clinical hypoperfusion (an inadequate flow of blood to the body’s organs) and the release of compensatory hormones aldosterone and arginine vasopressin (AVP) in neonatal foals. The study also seeks to understand how these physiological responses are associated with blood L-lactate concentrations.

Objective and Methodology

• The research studied the relationship between clinical signs of impaired organ perfusion and specific endocrine responses in normal- and under-perfused newborn foals.
• A prospective, multicenter observational study was conducted involving blood samples collected from 72 clinically under-perfused and 110 normal-perfused (including 73 hospitalised and 37 healthy) foals aged 4 days or younger.
• Foals were identified as clinically under-perfused if their L-lactate concentrations were ≥2.5 mmol/l and they exhibited one of several specified clinical factors including heart rate >120 beats/min, packed cell volume (PCV) >0.44 l/l or azotemia (increased creatinine and blood urea nitrogen [BUN]).
• Blood concentrations of aldosterone and AVP were determined with radioimmunoassays.

Research Findings

• The study results demonstrated higher concentrations of aldosterone, AVP, creatinine and BUN in clinically under-perfused foals compared to those which were normoperfused.
• Additionally, heart rate, PCV, and blood osmolality also recorded higher readings in clinically under-perfused foals (significant at P<0.05).
• The research identified a couple of risk factors associated with hypoperfusion, namely the presence of hypothermic extremities (increased OR by 5.26) and a unit increase in albumin concentration (increased OR by 3.5).
• The study proposed an admission L-lactate cut-off value of 10.6 mmol/l, above which non-survival in hospitalised foals could be reliably predicted, with a sensitivity of 82% and a specificity of 74%.

Conclusions

• The study reported that an increased production of aldosterone and VP, presence of hypothermic extremities, and increased albumin concentration are strong indicators of hypoperfusion in hospitalised foals.
• The research adds to the limited information available on the aldosterone and AVP responses to impaired organ perfusion and their association with L-lactate concentrations in newborn foals.