Fact Sheet - Equine Cushings Disease

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Fact Sheet by Dr Georgie O’Neil

What is it?

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  • An adenoma (tumour) in a part of the brain known as the pituitary gland

  • The pituitary gland is responsible for the production and stimulation of many hormones, most importantly dopamine

  • As dopamine levels are reduced, hormonal imbalances occur

Common Clinical Signs:

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  • Changes in hair coat; failure to shed fully, long hair (hypertrichosis) - only in ~60% of cases

  • Loss of muscle mass; loss of topline

  • Pot-bellied appearance

  • Increased water intake & urination 

  • Lethargy/dull or altered mentation

  • Sore footed or prone to laminitis

  • Typically, older horses with an average onset at 15 years

Testing/Diagnosis

  • Fasting ACTH concentration

    • Horse must be fasted overnight

    • Cost $175

  • Foot radiographs to monitor for signs of laminitis

    • For information regarding foot x-rays and their importance check out Motion Equine Podiatry Consulting blog - Foot X-rays

    • Cost $160 for 2 front feet, $250 for all 4 feet

 Treatment

  • Pergolide

    • Dopamine agonist: acts to restore inhibition to the pars intermedia

      therefore decreasing production of hormones such as ACTH

    • Perform baseline diagnostic testing before starting treatment

    • $86/bottle - works out to $2 a day for a 500kg horse or ~$1 a day for a pony

  • First 30 days should see

    • Improved attitude/performance, increased activity & sweating

  • Long term response 

    • Improved coat shedding, increased skeletal muscle along topline, less

      pronounced pot belly

  • Recheck resting ACTH concentration after 30 days to assess response to treatment 

  • Monitor insulin resistance to prevent laminitis

    • Fasting insulin & Glucose 

      • $175

Management

  • Nutrition

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  • If overweight: ration should consist mainly of hay and if feeding a hard feed, it needs to have a low glycaemic index

    • Hard Feed

    • Hay

      • Source & feed hay that has been tested for low non-structural carbohydrates (NSC)

      • 1st cut Lucerne hay can be a good example, especially after soaking in water

        • Soak for 60 minutes & allow hay to drip dry overnight & feed the next morning

    • Pasture

      • Limit pasture turnout

      • Pasture’s NSC content can vary greatly from season to season, day to day

      • Use of a grazing muzzle is a good option

    • Monitor weight and Body Condition Score

    • Exercise is important but depends on the degree and severity of the laminitic

      episode

  • If underweight: rations can be supplemented with additional calories from a

    low-starch, high-fibre products

    • Feeds that are designed for senior horses may not be desirable

    • Consider feed high in protein, fats and oil

      • Lupins

      • Prydes EasiSport

      • Consider using an oil high in omega 3&6

        • Recently trialling Hemp Seed Oil from Comanche Wellness

          for both an energy source and natural anti-inflammatory

If you would like more information, think your horse has Cushings and want to book an appointment

please don’t hesitate to contact us.

Luke Wells-Smith