Canine Developmental Bone Disorders Study Guide

Overview and Clinical Importance

Developmental orthopedic diseases (DOD) represent a group of conditions affecting the appendicular skeleton of young, rapidly growing dogs. Two of the most clinically significant conditions in this category are panosteitis and hypertrophic osteodystrophy (HOD). These conditions are frequently tested on the NAVLE and BCSE due to their breed predispositions, characteristic clinical presentations, and pathognomonic radiographic findings. Understanding the key differentiating features between these conditions is essential for accurate diagnosis and appropriate patient management.

Long Bone Anatomy Review

Understanding long bone anatomy is essential for localizing lesions in developmental bone disorders. The major anatomical regions include:

• Epiphysis: The expanded ends of long bones that form articulations; contains secondary ossification centers
• Physis (Growth Plate): The cartilaginous zone between the epiphysis and metaphysis responsible for longitudinal bone growth
• Metaphysis: The flared region between the physis and diaphysis; site of active bone remodeling and HOD lesions
• Diaphysis: The central shaft of the bone containing the medullary cavity; site of panosteitis lesions
• Medullary Cavity: The central cavity within the diaphysis containing bone marrow
• Nutrient Foramen: Small opening in the diaphysis through which the nutrient artery enters; often the epicenter of panosteitis lesions

Panosteitis (Eosinophilic Panosteitis, Enostosis)

Definition and Synonyms

Panosteitis is a self-limiting, painful inflammatory condition affecting the diaphyses of long bones in young, rapidly growing large and giant breed dogs. Alternative names include eosinophilic panosteitis, enostosis, endosteal proliferation of new bone, juvenile osteomyelitis, and colloquially "growing pains."