Before taking a blood sample, the patient should normally fast for 10 – 12 hours, provided the physiology of the species concerned permits this. Otherwise, faulty results are to be expected, especially for cholesterol, glucose and TLI. In addition, parameters such as á-amylase, ALT, AST, bilirubin, total protein, triglycerides, serum bile acids, leukocytes and calcium can be affected.
Fasted blood samples are not unproblematic in horses and only indicated for special tests (e.g. insulin and glucose for the diagnosis of the Equine Metabolic Syndrome). It is advisable to inform the owner about the influence of physical activity or stress on the results of a blood examination. Particularly muscular enzymes such as CK, LDH and AST can show increased levels in the serum after physical exertion. Additionally, glucose and lactate can also show elevated serum levels.
Before doing any allergy tests, including feedstuff tests, any administration of corticosteroids should be stopped. To do so, the following withdrawal times are recommended:
– local/topical corticosteroids: 2 – 4 weeks
– oral corticosteroids (e.g. Prednisolone): up to 8 weeks
– depot cortisone preparations (e.g. Voren®): up to 3 months
If these times cannot be observed, false negative results are possible. In the case of a positive result, the reaction class must be assessed taking into account the previous administration of cortisone.
Please note that other itch-suppressing medication may also have a negative impact on the allergy test. Our allergy team will be pleased to advise you.
Allergy tests should be performed during the season or at the end of the season and not earlier than one month after the onset of the symptoms, as the test may be false negative if performed out of season.