Equine Cushings Syndrome and Equine Metabolic Syndrome

Equine Cushings Syndrome

Pituitary Pars Intermedia Dysfunction

INTRODUCTION

Equine Cushings Syndrome (ECS) is an increasingly recognised condition in the aging equine.  It has increasing incidence with increasing age.  Once thought to be a tumour, it is now known to be dysfunction of the pituitary gland in the brain.  This sees an increase production of certain hormones which causes an increase in steroid production in the adrenal glands.

CLINICAL SIGNS

  • Identified usually in horses and more commonly ponies in their late teens onwards (occasionally younger).
  • Due to changes in the hair cycle, there is increased coat length and density extending to the thick curly coat easily recognised.  They sometimes have poor coat quality.
  • Abnormal fat distribution – fat pads above the eyes; or uneven fat pockets with areas of little fat covering.  There is often a generalised weight loss.
  • Recurrent or unexplained laminitis – due to the increased steroids, and steroids can cause laminitis; and changes in laminae structure.
  • Drink more water – often difficult to determine as it increases slowly over time.
  • Owners sometimes notice their equine has recently ‘aged’ or lethargic.
  • Slow healing of wounds or unexpected wounds – sometimes seen as cheek ulcers in the mouth at dental health checks without identifiable sharp points; or rug rubs at the withers that never quite heal; or outbreaks of lice.

DIAGNOSIS

  • A tentative diagnosis of ECS can be made based on clinical signs.
  • A simple blood test can be taken (processed and posted frozen) and sent measuring the hormone ACTH – these results take a few days to come back and tries to identify an increased production.
  • Insulin can be measured and is often higher in ECS but not always.  This is particularly important in cases of laminitis.
  • Dexamethasone Supression Test is needed in some (often more subtle) cases.  Following administration of an injection of steroids on day 1 a blood sample is taken to measure cortisol, and then a blood sample is taken again on day 2.  In normal horses, they drop their own steroid production in response to the steroid injected.  In ECS horses there is not this recognition and their sample changes very little.
  • Other tests may be used if necessary.

TREATMENT

The mainstay of ECS treatment is Prascend (the drug contained is pergolide).  This is a dopamine agonist working on the brain and is effective in up to 80% of cases.  It usually involves 1 1mg tablet a day but this dose can be increased or decreased depending on the size of the individual and the extent of the result.  There are limited side effects although the most common is a change in apetite or a change in behaviour – although most people notice a much improved behaviour!  The cost of administration is just over £1 a tablet at the moment.

In cases resistant to Prascend, a drug called trilostane can be used.  This works by reducing the steroid production on the adrenal glands and can be useful.  It involves between 1 to 4 120mg tablets a day and costs more per day to treat.

Other than pharmaceutical help, other things can be done to help the individuals.  Clipping the coat (either full or a trace of the neck and belly) can help the individual thermoregulate better and sweat less.  The diet can be changed to allow for easier access fibre and weight gain / balance.  Trying to prevent laminitis is vitally important – care with rich grass, good foot management, etc.

PROGNOSIS

Some individuals can have their ECS controlled and kept happy and comfortable for many years (ten plus!).  Most patients are very happy on their medication and thrive.  Recurrent laminitis or laminitis unable to be controlled is the biggest factor in early loss of life.

 

Equine Metabolic Syndrome

INTRODUCTION & CLINICAL SIGNS

Equine Metabolic Syndrome is a recently recognised condition in the equine, genetically ponies are more at risk and especially native breeds.

INSULIN RESISTANCE is a key feature.  This means the body produces insulin, and does not act on it, so the body produces more and more, but still does not really respond to it.

These ponies and horses are OBESE and described as ‘good doers’ – genuine strict dieting still does not lead to weight loss.  They will have a higher condition score and particularly carry fat on the crest.

Both of these fact lead to an increased incidence of LAMINITIS – clinically (noticeable) or subclinically (more subtle cases, diverging rings on the hooves).

This has previously been termed ‘Peripheral Cushings Syndrome’ – this is inaccurate, although some can be a little pot-bellied and lethargic like ECS cases.  ECS cases are usually mid / late teens onset, whereasEMScases are often identified in late single figures / early teens.

DIAGNOSIS

  • A blood test can measure INSULIN (normally <40 but can be 100s or over a 1000) and GLUCOSE (infrequently a problem but should be checked).  These should be taken ‘rested’ and not after stress – such as during an acute laminitic episode or following transport
  • More milder cases need further testing, being the combined glucose – insulin tolerance test.  This involves an injection of insulin after a glucose feed.  EMS cases have a higher peak than normal cases, a longer drop to normal and less of a drop to negative than normal cases – this is measured through repeated blood tests over 2 ½ hours.
  • A good compromise is the in-feed glucose challenge test which involves fasting the equine overnight (12 hours), feed a chaff with glucose, and then the vet visits to take a blood test.

TREATMENT

It is very important for the equine to lose weight through strict careful dieting – we can advise you on a suitable diet which is low in sugar and high in fibre (little amounts of grass, soaked hay, high fibre chaff).

Regular exercise is fundamental to weight loss.  This should be regular and daily if possible, it can be ridden or lunging is a good time sparing way to exercise your equine.

The use of metformin is often vital in these cases and may be short term or much longer term.

Careful and prompt treatment of any laminitis that occurs is vital – this includes careful management of the feet.

Through these steps of management, a successful life can be maintained!

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