Cartilago nasi accessoria
The equine nasal cartilages support the nasal passages. Major components include the dorsal lateral nasal cartilage, the ventral lateral nasal cartilage, the alar cartilage (with its lamina and cornu that form the framework of the nostril), and the nasal septum cartilage that divides the nasal cavity into left and right sides. The alar cartilage is especially important because active muscular dilation of the nostril increases the aperture during exercise and reduces airway resistance. At rest the equine nostril is comma-shaped; during exercise it becomes more circular. The false nostril (diverticulum nasi) is a blind-ended pouch on the dorsolateral aspect of the nostril. Horses cannot breathe through their mouths because of the long soft palate overlapping the epiglottis, so any restriction of nasal airflow directly affects performance and can become life-threatening.
Any condition that reduces nasal airflow impacts performance. Evaluation of the nasal passages is indicated in horses with abnormal respiratory noise, nasal discharge, or poor performance. Epistaxis (nosebleed) after exercise is most often exercise-induced pulmonary hemorrhage until proven otherwise, but unilateral resting epistaxis suggests local nasal or guttural pouch disease. Deviation of the nasal septum or septal hematoma can cause unilateral obstruction. Dynamic endoscopy is useful for exercise-related noise.
A small amount of clear nasal discharge after exercise or in dusty conditions is normal. Call the veterinarian for thick yellow or green discharge (especially from one side), blood from the nostrils at rest, food material at the nostrils, foul-smelling discharge, or any discharge with fever or swollen lymph nodes. Abnormal respiratory noise during exercise warrants evaluation. Both nostrils should dilate equally.
Any condition that reduces nasal airflow impacts performance. Evaluation of the nasal passages is indicated in horses with abnormal respiratory noise, nasal discharge, or poor performance. Epistaxis (nosebleed) after exercise is most often exercise-induced pulmonary hemorrhage until proven otherwise, but unilateral resting epistaxis suggests local nasal or guttural pouch disease. Deviation of the nasal septum or septal hematoma can cause unilateral obstruction. Dynamic endoscopy is useful for exercise-related noise.
A small amount of clear nasal discharge after exercise or in dusty conditions is normal. Call the veterinarian for thick yellow or green discharge (especially from one side), blood from the nostrils at rest, food material at the nostrils, foul-smelling discharge, or any discharge with fever or swollen lymph nodes. Abnormal respiratory noise during exercise warrants evaluation. Both nostrils should dilate equally.
See the Nasal Cartilage (Accessory) on our interactive 3D horse model. Open 3D Model