Equine endocrine diseases, laminitis and liver Flashcards
Aetiology of PPID in horses
Progressive degeneration of hypothalamic dopaminergic neurons –> get loss of control over part intermedia causing hyperplasmia and adenoma in pars intermedia
Then pars intermediate produces lots of POMC and get elevation in peptides including ACTH
Clincial signs of PPID
Pathognomic one = hypertrichosis
Coat retentino
Chronic laminitis
Why are reference values for basal ACTH different with time of year
There is natural pituitary hyperactivity in autumn
Why do we have a grey zone of ACTH concentration resutls
Up to 25% of PPID horses fall in grey zone
Up to 30% non-PPID horses in grey zone
So interpret in context of clinical signs
Allows higher sensitivity
What age animals are more likely to have false +ve for PPID
young
When not to test a horse for PPID
IF it has had severe pain for 24 hrs or more
If it has travelled in past 12hrs
Treatment of PPID
= pergolide
To replace dopaminergic control of pars intermedia
2mg/kg/day
Side effects of pergolide treatment
Transient inappetance
- If get this can stop and restart at a lower dose after 2 week washout
Reduced milk production; stop treatment for 6 weeks pre-partum
How do we monitor success of pergolide in managing PPID
CHeck ATCH concentration
Insulin and clinical assessment
- Increased insulin very important in laminitis so this is key clinical outcome; if insulin is still high, more likely to continue increasing pergolide dose than with high ACTH but good insnulin control
Why is it important to keep on top of dentistry in PPID horses
To ensure they keep eating well and issues are picked up sooner
What is equine metabolic syndrome
Collection of risk factors for hyperinsulinaemia assocaited laminitis
Consident feature = insulin dysregulation
Mixture of environment and genetics
Which horses are at high genetic risk of EMS
Miniature horses, native ponies, warmbloods
- Only need more mild environmental influences to provoke EMS
Signs of subclinical laminitis
Divergent rings; wider at heel than front of foot = marker of historic laminits
Footsore after trimming.
doesn’t like hard ground
How long do divergent rings take to appear after laminitis
3 months
Lab tests for EMS
Unfasted sugar = low sensitivity test
Dynamic test = karo syrup challenge
–> Fast then give Karo light corn syrup and take sample to test for glucose, insulin, trigylcerides an hour later
Adiponectin test = for adipokine peptide
> Low levels assocaited with EMS and metabolic obestiy
What adiponectin levels are assocaited with EMS
<7.9microg/ml
Diet for EMS horse
Starch and sugar must make up <10% of diet
IF overweight want to lose weight but can’t let dry matter intake go below 1% body weight
Haylage is a good option
Medications for EMS (increasing risk level)
Metformin: impairs glucose absorptions and reduces insulin response to glucose ingestion
Levothyroxine speeds up metabolism
Gliflozins block glucose uptake rom renal filtrate [take care since liver disease risk]
What side effects are there with levothyrozine for EMS treatment
Makes horses hyperthyroid so if stopping can get hypothyroiism
High doses can make horses fizzy; excitable, box walking
When might we use Gliflozins in EMS treatment
In an emergency with very high laminitis risk; because very good at bringing insulin down via blocking glucose uptake from renal filtrate
BUT: there are reports of peracute liver disease
Also risk of bringing triglycerides up too high