Equine Endocrinology

Overview of Equine Endocrine Diseases

• Common endocrine disorders in horses:

  • Equine Metabolic Syndrome (EMS)

  • Pituitary Pars Intermedia Dysfunction (PPID)

• Importance of recognizing symptoms, signalment, and management strategies.

Key Objectives

• Compare and Contrast EMS and PPID

  • Signalment

  • Clinical Presentation

• Design Testing Strategies

• Develop Management and Therapeutic Strategies

Signalment and Clinical Presentation

Equine Metabolic Syndrome (EMS)

• Prevalent in:

  • Younger to middle-aged horses (not typically 19 years or older)

  • Breeds particularly affected: Peruvian Pasos, Pony breeds, Morgans

• Clinical Signs:

  • General obesity

  • Abnormal fat deposition (especially neck crest, tail head, and sheath in geldings)

  • Increased risk of laminitis

  • Difficulties in breeding for mares

Pituitary Pars Intermedia Dysfunction (PPID)

• Commonly seen in:

  • Older horses (usually >15 years old; often diagnosed around 19-21 years)

  • Some breeds like ponies may be predisposed, but this is less common now

• Clinical Signs:

  • Hypertrichosis (longer hair coat; not hirsutism)

  • Muscle wasting leading to potbellied appearance

  • Increased risk of laminitis

  • Infections (secondary due to hormonal imbalance)

Differentiating Between EMS and PPID

• Clinical Signs: look for overlaps

• Signalment: age, body condition, and breed can provide important context

• Emphasize testing if clinical signs are vague; don’t rule out EMS based solely on age or presentation

Testing Strategies for EMS

• Resting insulin and glucose tests:

  • High insulin levels indicative of insulin resistance

  • Look for insulin dysregulation, but this alone does not confirm EMS

• Dynamic Tests:

  • Oral Sugar Test (Karo syrup): measures insulin response to an oral glucose load

  • Insulin Tolerance Test: assesses glucose response to insulin administration

Testing Strategies for PPID

• Resting Plasma ACTH Levels:

  • ACTH elevation indicates PPID

• TRH Stimulation Test:

  • Effective for early detection of PPID; can affirm diagnosis if positive.

• Dexamethasone Suppression Test:

  • Less commonly used now; not preferred due to variable results

Management and Therapeutic Strategies

EMS Management

• Focus on:

  • Weight management through diet (low-sugar feeds)

  • Reducing caloric intake

  • Regular exercise

• Monitor for laminitis

PPID Management

• Treatment may require lifelong administration of Pergolide.

• Monitor and reassess every 3-6 months after initiating treatment.

• Be cautious before starting treatment without definitive diagnosis; consider potential side effects.

Conclusion

• Regular updates from the Equine Endocrine Group are valuable for current practices.

• A good understanding of EMS and PPID, along with appropriate diagnostic tests and management strategies, is crucial for effective equine practice.