Articles
Understanding DOD and Splints in Horses: Causes, Signs & Nutritional Support

Understanding DOD and Splints in Horses: Causes, Signs & Nutritional Support

Developmental Orthpaedic Disease (DOD)

Developmental Orthopaedic Disease (DOD) is an umbrella term that refers to a range of joint and bone abnormalities that primarily affect young, growing horses. These disorders can impair growth, cause pain and lameness, and limit long-term athletic potential if not managed early and correctly. Splints, a common orthopaedic issue in horses, may occur in both young and mature horses due to concussion or limb strain.

How to Recognise DOD and Splints Signs of DOD: 

  •  Puffy or swollen joints (especially knees and hocks) 
  •  Warmth and tenderness in joints 
  •  Stiffness or reluctance to move 
  •  Lameness, particularly at the start of training 
  •  Angular limb deviations 
  •  Pain on flexion or joint manipulation 
  •  Poor coordination (in cases like Wobbler's Syndrome) 

 Signs of Splints: 

  •  Hard, bony swelling along the inside of the cannon bone 
  •  Heat and pain in the affected area (early stage) 
  •  Lameness (mild to moderate depending on severity) 
  •  Visible or palpable splint bump






What Is DOD in Horses? 

 DOD encompasses a group of developmental disorders that affect bones, joints, growth plates, and cartilage in young horses. 

These conditions generally result from: 

  • Rapid growth 
  •  Nutritional imbalances 
  • Genetic predisposition 
  •  Overfeeding or overexercising young horses 
 DOD conditions often involve improper ossification (the conversion of cartilage to bone), leading to limb deformities, joint pain, and even permanent lameness. 

 Common DOD Conditions Include: 

  •  Osteochondritis Dissecans (OCD) 
  •  Epiphysitis 
  •  Wobbler's Syndrome 
  •  Flexural and Angular Limb Deformities 
  •  Bog Spavin
  •  Contracted tendons 
  •  Club feet 

What Are Splints in Horses? 

Splints refer to bony growth or inflammation along the splint bones (small bones on either side of the cannon bone). They commonly occur in young horses entering work or mature horses under heavy training. 

 Splints can result from: 

  •  Repetitive concussion on hard ground 
  •  Poor conformation 
  •  Trauma to the limb 
  •  Excessive workload or improper training

How to Recognise DOD and Splints 

Signs of DOD: 

  •  Puffy or swollen joints (especially knees and hocks) 
  •  Warmth and tenderness in joints 
  •  Stiffness or reluctance to move 
  •  Lameness, particularly at the start of training 
  •  Angular limb deviations 
  •  Pain on flexion or joint manipulation 
  •  Poor coordination (in cases like Wobbler's Syndrome) 

 Signs of Splints: 

  •  Hard, bony swelling along the inside of the cannon bone 
  •  Heat and pain in the affected area (early stage) 
  •  Lameness (mild to moderate depending on severity) 
  •  Visible or palpable splint bump 

What Causes DOD and Splints in Horses? 

 While the exact cause of DOD is not fully understood, research and field experience suggest a combination of: 

 Nutrition: 

Diets high in non-structural carbohydrates (NSC), ike grain and molasses, can lead to insulin spikes that interfere with normal cartilage development. 

Mineral Imbalances: 

Deficiencies or imbalances in calcium, phosphorus, copper, and zinc affect bone growth and ossification. 

 Rapid Growth: 

Fast growth rates increase the risk of developmental abnormalities, especially in foals pushed with high-calorie, high-starch feeds. 

 Excessive Exercise: 

Overworking young horses before their skeletal system matures can cause lasting damage. 

 Genetics: 

Some bloodlines have a higher prevalence of DOD studies suggest up to 45% of foals in certain lines may be affected. 

High-grain, high-energy diets (NSC >12%) in yearling sales preparation have been strongly associated with lameness and joint issues due to overnutrition and storage of proteoglycans in the tendons and connective tissue.

 How Nutrition Affects DOD and Splints 

 Proper nutrition is critical in preventing and managing DOD and supporting healthy joint development. Key dietary considerations include: 

 Avoid: 

  •  High-NSC feeds (grain, sweet feeds, molasses-based pellets) with NSC >12%
  • Diets where more than 50% is grain or molasses-based and NSC >12%
  • Overfeeding calories, especially to young, rapidly growing horses 
  •  Excess body condition (being overweight stresses joints) 

 Provide: 

  •  Moderate energy feeds with low starch and sugar NSC <12% such as copra meal
  • Balanced mineral intake, especially: Calcium & phosphorus in the correct ratio (~2:1) Copper and zinc to support cartilage and bone development . Tendon support supplements such as Proflex
  • Controlled protein (ideally 14–16% for growing horses) 
  •  Plenty of forage and fibre to slow digestion and reduce glucose/insulin spikes Important Note: Low protein diets (<12%) can also cause growth abnormalities and poor bone mineralisation. Balance is key. 

 Managing and Preventing Splints 

 To help prevent splints, especially in young horses starting work: 

  •  Avoid fast work on hard surfaces 
  •  Allow progressive loading and conditioning 
  •  Use balanced hoof care and trimming to reduce limb strain 
  •  Ensure dietary mineral balance to support bone strength 
  •  Provide ample turnout and avoid confinement stress 

Summary: Supporting Joint Health in Young Horses 

 DOD and splints can significantly affect the long-term soundness of horses. Understanding how nutrition, exercise, and management impact joint development is key to preventing these issues. By feeding a balanced, low-starch, mineral-rich diet, and avoiding excessive strain on growing limbs, you can help support strong bones and healthy joints in young horses.

Information Articles orthopaedic splints joints low NSC lameness copra developmental disease