Paranasal sinuses in the Horse


  • Sinuses are recesses that arose of outpocketing of nasal canal.
  • They are spaces within the bones of the head and aligned with mucosal membrane.
  • Not sure of function but probably help decrease weight of skull.
  • Horse maxillary sinus is divided into rostral/caudalparts via bony septum, 5 cm behind rostral border of facial crest.  Also have partial midline division by bony wall that supports infraorbital canal.
    • All sinuses drain into middle meatus via maxillary sinus lateral compartment.
    • Caudal maxillary sinus receives drainage from the Spheno-palatine sinus and concho
      -frontal sinus (both frontal and dorsal conchal).
        Caudal compartment houses cheek teeth 5-6, dental infection can cause problems.
    • Rostral maxillary sinus receives drainage from ventral conchal sinus. 
    • Infraorbital canal partition means that puss has to go over infraorbital canal to get to drain in ventral compartment, eventually middle meatus.
    • Rostral houses cheek teeth 3-4.
  • To access maxillary sinus, caudal border is aligned from middle cantus to facial crest.  Rostral border is parallel to caudal but bisects facial crestVentral border is facial crest and dorsal border is imaginary line from lateral canthus of eye to infraorbital foramen. 





Frontal sinus = drains into maxillary sinus, not middle meatus.  If aged horse gets oral infection of tooth it is likely to cause sinusitis of maxillary and possibly to frontal bc of the connection with dorsal conchae.  Frontal sinus in frontal bone and divided into 3 section, rostral, lateral and medial frontal sections. 

  • Sphenoidal sinus = communicates with nasal cavity by frontal and cd. Maxillary sinus.
  • in horse draw line from medial canthus of eye to lateral base of ear and aim where two lines intersect when euthanizing horse.

About Annettevet

I'm a Norwegian practicing as a veterinarian in Durham, England. I`ve recently qualified as a veterinarian at Glasgow University. This is a blog about my experiences as a vet student and now as a veterinarian. “The greatness of a nation and its moral progress can be judged by the way its animals are treated”
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