New Endocrinology group Flashcards
TRH Test and OST, food?
Horses can be tested after hay is fed, but not within 12 hours after a grain meal.
Testing ok before OST but NOT within 12 hours after OST.
TRH stim any time of the year?
JULY to DECEMBER difficult!!!
MANY false positives
SO only ok to confirm negative
Starting dose for Pergolide
What to do if no response?
1mg for 500kg
re-test after 3m (then every 6-12)
if not good-> increase dose by 0,5 or 1mg/500kg
MAX 3mg/500kg + cyproheptadine
OR
go up to 5mg/500kg (off-label)
OTHER POTENTIALLY SUPPORTIVE TESTS
of PPID besides basal ACTH or TRH Stim
Overnight dexamethasone suppression test
Magnetic resonance imaging (MRI) specific for pars intermedia enlargement
What if good clinical response to Pergolide but ACTH remains high?
May increase dose or maintain dose
PRACTICE TIP: Improvement in
clinical signs and insulin status is
the most important indicator of
response to treatment.
ACTH
concentrations may remain in the
PPID likely or equivocal zone
despite clinical improvement,
and do not always warrant a
dosage increase.
horse inappetent with Pergolide
stop treatment until appetite returns and or decrease by half for 3 to 5 days and then titratenback up in 0.5 -1 mcg/kg steps every 2 weeks until the desired dose is achieved.
What happens to ACTH values if you stop pergolide?
ACTH concentrations may begin to increase within 48 hours, but the risk of
clinical signs worsening during this period is low.
takes 10d to return to previous level
Can you test horses with laminitis for PPID?
Low to moderate pain of at least 24 hours duration does not appear to impact diagnostic testing with baseline ACTH or TRH stimulation testing. Testing may be performed in laminitic horses, but it is
ideal to postpone until severe pain is controlled.
Sedation and PPID testing
ideal to avoid diagnostic testing for
PPID and insulin status within 24-48 hours of sedation.
ACTH baseline may be possible within 5-10mins after xyl/deto with or without butorphanol
PPID testing during stress
Stress, excitement, and trailering can result in a transient increase in ACTH concentrations. Samples for PPID
diagnosis via baseline ACTH should not be collected within 30 minutes of trailering, or in an animal that is
visibly excited.
HAL and PPID
HAL is detected in approximately 30% of horses with PPID and horses greater than 10 years of age should be tested
EMS at risk breeds
Pony breeds
Spanish Breeds (e.g., Andalusians)
Gaited breeds (e.g., Saddlebreds, Paso Finos)
Morgans
Miniature horses
Warmbloods
Uncertain genetic risk: Donkey
Typical EMS signs apart from obesity and laminitis
Divergent hoof rings (subclinical laminitis)
Preputial or mammary gland enlargement (adipose tissue +/- edema)
Clinical problems may be historical or current
impact of EMS on fertility?
YES
How long is insulin stable in blood tubes?
- Insulin is stable in plasma or serum for at least three days when separated from red blood cells and refrigerated (4°C).
Difference between OST and ITT
**OST is preferred **bc assesses
* digestion and absorption of sugars,
* incretin hormone responses,
* secretion of insulin from the pancreas and
* risk of HAL
ITT focuses solely upon hepatic and/or
peripheral tissue insulin sensitivity
What is the disadvantage of OST and which changes are clinically relevant?
low within-horse repeatability of results
POSITIVE: >65uU/ml after 1 or 1,5hrs
binary changes in the positive or negative
result and **major shifts in insulin concentrations (> 30 µU/mL) **are considered clinically significant
Who might be at risk for dangerous ITT hypoglycemia?
lean insulin-sensitive animals. An additional blood
glucose measurement at 15 minutes is recommended for these animals as an added precaution
Are Insulin concentrations affected by season?
YES
higher concentrations detected in
December, January, and February in the Northern hemisphere, suggesting a winter-associated exacerbation of ID.
Can I perform OST and ITT on the same day?
It is not recommended to perform the OST
and ITT on the same day
In previously laminitic EMS horses with recovered and stable hoof lamellae, minimum exercise recommendations are
low intensity exercise on a soft surface (fast trot to canter unridden; or heart rates 130-150 bpm) for >30 minutes, >3 times per week,
In EMS horses with ID and no signs of lameness, minimum recommendations are
low to moderate intensity exercise
> 5 times per week such as canter to fast canter (ridden or unridden) achieving heart rates of 150-170 bpm for >30 minutes.
also been shown that 15 minutes of moderate trotting (with 5 min walking to warm up and warm down) 5 times per week has a significant beneficial effect on insulin sensitivity in obese equids
Feeding obese horses with EMS
hay with NSC content < 10% (or grass hay) in 1,5% of BW
measure BW every 30d and decrease to min 1,2%
soak in cold water for 60mins
up to 50% good quality straw possible
drugs if weight loss resistant despite management
- High-dose levothyroxine (max 3-6m): NOT in non-obese horses
- Sodium-glucose co-transporter 2 (SGLT2) inhibitors, ACHTUNG hypertriglyceridemia!!
- Metformin hydrochloride
Management recommendations for non obese EMS horses
diet with low-NSC, high-fat, and high-quality fiber content such as beet pulp or soy hulls.
Provide a low-sugar mineral/vitamin/protein ration balancer.
Exercise remains the same as in obese animals
TRH and ITT together?
Yes a combinded test, injecting the two at the same time, is available.
