Musculus serratus dorsalis caudalis
The caudal dorsal serratus (serratus dorsalis caudalis) is a thin, fan-shaped expiratory muscle. It originates from the thoracolumbar fascia (spinous processes roughly T15–L2) and inserts on the caudal borders of the last 4–5 ribs. When it contracts it draws those ribs inward and caudally, assisting active expiration. It works in opposition to the cranial dorsal serratus, which aids inspiration. It is innervated by the intercostal nerves. Because it is thin and deep to other muscles, isolated injury is rare. It becomes more relevant during exercise when respiratory demand increases.
Origin: Thoracolumbar fascia from spinous processes of T15-L2
Insertion: Caudal border of last 4-5 ribs
Action: Retracts the caudal ribs during expiration
Innervation: Intercostal nerves
Rarely a primary clinical focus. Rib fractures or severe thoracic trauma can affect it secondarily. Reduced respiratory effort or pain on deep palpation of the caudal thorax may involve the serratus muscles along with intercostal muscles.
## Overview Chronic obstructive pulmonary disease is an older term for what is now called severe equine asthma (previously also known as recurrent airway obstruction or heaves). It is a chronic infla
Difficulty breathing after a fall or trauma that involves the rib cage should be evaluated by a veterinarian. Most isolated muscle strains improve with rest.
## Overview Chronic obstructive pulmonary disease is an older term for what is now called severe equine asthma (previously also known as recurrent airway obstruction or heaves). It is a chronic inflammatory airway disease triggered by environmental dust and molds, producing coughing, increased respiratory effort, and exercise intolerance. ## Causes Hypersensitivity to organic dust, molds, and endotoxin in hay and bedding. A summer-pasture form also exists in some regions. ## Diagnosis History of cough and labored breathing in a dusty environment, endoscopy showing excess mucus, and bronchoalveolar lavage cytology demonstrating neutrophilic inflammation. ## Treatment Environmental management (low-dust feed and bedding, improved ventilation) is the cornerstone. Corticosteroids and bronchodilators control flare-ups. ## Recovery and Prognosis The condition is manageable but not curable. Horses kept in clean air often remain comfortable and useful; continued exposure leads to progressive decline. ## Prevention Lifelong attention to air quality in the stable. Signs include: chronic cough; increased respiratory effort; nasal discharge; exercise intolerance; worsened signs in dusty environments
Rarely a primary clinical focus. Rib fractures or severe thoracic trauma can affect it secondarily. Reduced respiratory effort or pain on deep palpation of the caudal thorax may involve the serratus muscles along with intercostal muscles.
Difficulty breathing after a fall or trauma that involves the rib cage should be evaluated by a veterinarian. Most isolated muscle strains improve with rest.
See the Caudal Dorsal Serratus on our interactive 3D horse model. Open 3D Model