Agenesis and Dysgenesis of the Navicular Bone as Cause of Lameness and Malalignment in Two Foals.

The research article discusses two cases of foals with lameness—one a warmblood colt with a two-week history of lameness, and the other a Quarter Horse-mix filly with malaligned pelvic limbs since birth. Both were diagnosed with conditions related to the navicular bone—the former with agenesis (absence), and the latter with dysgenesis (malformation).

Clinical Signs

The researchers examined two foals with different cases. Symptoms were mostly related to the functionality and movement of the foals:

• Three-week-old warmblood colt: Exhibited lameness in the left thoracic limb for two weeks.
• Two-month-old Quarter Horse-mix filly: Had malaligned pelvic limbs that had been present since birth.

Diagnostics

The team conducted diagnostic tests on both foals to provide accurate diagnosis:

• Warmblood colt: The primary diagnosis was agenesis of the navicular bone, a condition characterized by the absence of the navicular bone in the horse’s hoof. This was concluded from signs of lameness.
• Quarter Horse-mix filly: Was diagnosed with navicular bone dysgenesis, a condition where the navicular bone is malformed or not completely developed. This was evident due to the foal’s malaligned pelvic limbs.

Postmortem Workup

The researchers proceeded with a postmortem examination on both foals. The details of these examinations were not mentioned in the abstract. These examinations usually include a thorough investigation of the deceased animal to confirm the initial diagnosis and to further understand the cause or implications of the disease. Inferring from the presence of these examinations, it can be deduced that both foals did not survive their respective conditions. The results of the postmortem examination could inform future treatments and preventions for navicular bone anomalies.