1. Tools for the diagnosis of equine respiratory disorders
Marie-France Roy, DMV, Jean-Pierre Lavoie, DMV 
Veterinary Clinics: Equine Practice 
Volume 19, Issue 1, Pages 1-17 (April 2003)
DOI: /S (02)

2. Fig. 1
Preferred site for entering the frontal sinus. This site also gives access to the caudal maxillary sinus through the frontomaxillary opening. Distance a: 0.5 cm caudal to a line joining both medial canthi. Distance b: 60% of the distance, in a lateral direction, from midline to the medial canthus.
Veterinary Clinics: Equine Practice  , 1-17DOI: ( /S (02) )

3. Fig. 2
Preferred site for entering the caudal maxillary sinuses, which allows visualization of the sphenopalatine sinus. Distance a: 2 cm rostral to the medial canthus. Distance b: 2 cm ventral to the medial canthus.
Veterinary Clinics: Equine Practice  , 1-17DOI: ( /S (02) )