Urinary enzyme concentrations in healthy horses.

The research investigates the concentration of four enzymes in the urine of healthy horses, exploring possible variations based on time, sex, and age of the animals. The study finds that these factors do not significantly influence the observed enzyme levels.

Objective and Methodology of Study

• The primary goal of this study was to measure and analyze the concentrations of four enzymes – gamma glutamyl transferase (GGT), alkaline phosphatase (AP), aspartate aminotransferase (AsAT), and alanine aminotransferase (AAT) – in the urine of 32 healthy horses.
• The study subjects were divided into four different age groups, made up of both geldings (castrated male horses) and females, to inspect the influence of age and sex on urinary enzyme levels.
• For ten of the geldings, continuous urine samples were collected over a 72-hour period at specific time intervals, to evaluate any diurnal (daily) variation in enzyme activity.

Key Findings

• The study found that urinary enzyme activity in horses was not influenced by serum concentrations of the same enzymes, contrary to what might be expected.
• Neither did the activity of the urinary enzymes vary based on the time of day the samples were taken, indicating a lack of diurnal variation.
• Age and sex of the horses also did not influence the urinary enzyme activity, regardless of whether the activity was expressed in absolute terms or relative to creatinine excretion, a common marker for enzyme activity.
• The study established normal values for GGT and AP enzymes, while finding that the enzymes AAT and AsAT were not present at detectable levels in the urine samples.
• The average urine creatinine concentration, a measure often used to ‘normalize’ enzyme activity in urine, was determined, revealing no significant variation with respect to age or sex.

Implications of the Findings

• This study is important as it provides a baseline understanding of the normal levels of the key enzymes found in horse urine. Such information can be valuable in diagnosing and monitoring disease conditions in horses that may affect enzyme production and activity.
• The findings also suggest that variations in enzyme concentrations in horse urine samples cannot be attributed to factors like sex, age, or time of day the sample was taken. This can help guide the interpretation of clinical tests in equine veterinary practice.