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Dogs
PRE-TRILOSTANE CORTISOL
Used for monitoring Vetoryl (trilostane) treatment, in combination with the clinical signs, from 4 weeks after commencement of trilostane treatment.
Collect a blood sample immediately before the trilostane is administered.
Suitable for:
- Dogs on once- or twice-daily Vetoryl dosing
- Adrenal and pituitary-dependent hyperadrenocorticism
- Clinically well dogs (with or without signs of hyperadrenocorticism)
- Calm dogs.
Unsuitable for:
- Aggressive or stressed dogs, or unwell dogs, in which case an ACTH stimulation test should be performed.
Canine ACTH stimulation test
This test is used for the diagnosis of hypo- and hyperadrenocorticism, for monitoring dogs on treatment of hyperadrenocorticism and for diagnosis of iatrogenic hyperadrenocorticism.
- Collect basal sample to provide 0.5 ml serum, label ‘pre’
- Inject synthetic ACTH (Synacthen) IV. The dose is 0.25 mg for dogs > 5kg and 0.125 mg for dogs < 5 kg
- Take a second sample 60 minutes later, label ‘post’
- Separate the serum.
When used to monitor the effectiveness of trilostane therapy, the test is performed 4 - 6 hours post capsule. Monitoring is usually performed 10 - 14 days, 30 days and 90 days after starting therapy and then every 3 - 6 months.
NB This test is not useful for monitoring Addisons disease once this has been diagnosed.
Low dose dexamethasone suppression test, dogs.
This test is used to identify hyperadrenocorticism. It is more sensitive than the ACTH stimulation test although has a higher incidence of false positive results due to non-adrenal illness.
- Collect basal sample to provide more 0.5 ml serum, label the separated serum ‘pre’
- Inject 0.01 mg/kg soluble dexamethasone IV
- Take samples at 4 and 8 hours post dexamethasone, label the separated serum with times.
SHAP Test (17OHP pre and post ACTH) in dogs
This is used to evaluate cases of alopecia suspected to be due to sex hormone excess. It is also used to evaluate animals with suspected Cushing’s but which have normal ACTH stim and low dose dexamethasone tests. In such cases there may be a derangement of the normal steroid production pathway with accumulation of cortisol precursors including 17 hydroxyprogesterone (17-OHP). The method is identical to the ACTH stimulation test: 17-OHP is measured pre and 1 hour post ACTH.
Cats
The best test for diagnosing feline hyperadrenocorticism has not been established. The ACTH stim test has a reported sensitivity of 50-80%. The low dose dexamethasone suppression test may be more sensitive but too few cases have been assessed. Sometimes both tests are performed.
Low dose dexamethasone tests, cats
- Collect basal sample to provide more than 0.5 ml serum, label the separated serum ‘pre’
- Inject 0.1 mg/kg soluble dexamethasone IV (note higher dose than used in dogs)
- Take samples at 4 and 8 hours post dexamethasone, label the separated serum with sample times.
Feline ACTH stimulation test
The time of peak response to ACTH is variable and so multiple samples are taken post ACTH.
NB this test has been reported to be less sensitive than the low dose dexamethasone test in cats
- Collect basal sample to provide more than 0.5 ml serum, label the separated serum ‘pre’
- Inject synthetic ACTH (Synacthen) IV. The dose is 125 μg for cats < 5kg and 250 μg for cats > 5kg
- Take samples at 1 and 3 hours post ACTH, label the separated serum samples with sample times.