1. Normal Radiographic Anatomy of the Equine Head Dr. Pack/Woodland April 7, 2011.

2. Indications • Nasal Discharge • Sinusitis • Dental Disease • Head Trauma • Fractures • Facial / Neck Swelling • Guttural Pouch Tympany

3. Technical Considerations • Head is mobile and high off the ground • Sedation • Lowers head • Can use portable equipment • 14x17 cassettes • Film holding device • Rope halter – no buckles

4. Lateral and Oblique Views • Standing or recumbent • Can visualize sinuses, teeth and skull fractures (frontal bone) • Obliques are needed to carefully assess tooth roots • Must label correctly • Can use barium as marker on skin if needed

5. Morgan

6. Morgan

7. Morgan

8. DV/VD • Used for comparison between sides • Difficult to keep head still and straight • Can throw off symmetry • Easier to do VD when patient is under general anesthesia • Maxilla is wider than the mandible

9. Morgan

10. Mass on Right side

11. Cranium • Foals: dome-shaped • Face lengthens with growth; accommodates teeth and expanding sinuses • Adult lateral view • Petrous temporal bones (tympanic bullae not visible) • Nuchal crest • Occipital condyles • Ethmoid turbinates

12. A B C D E F Dyce et. al A - Nuchal crest D - Occipital condyle B - Coronoid process E - Ramus of mandible C - Condylar process F - Body of mandible

13. Equine Skull • A = Petrous temporal bone • B = Cranium • C = Condyloid process • D = Coronoid process • E = Basioccipital • F = Epiglottis • G = Ethmoid turbinates

14. A – Choncofrontal sinus B – Maxillary sinus C – Condylar process of mandible D – Guttoral pouch E – Stylohyoid bone F – Epiglottis G – Maxillary 3rd Molar H – Mandibular 2nd Premolar A C B D G E F H

16. Equine Sinuses • Frontal • Dorsal part of the skull, medial to orbit • Combines with dorsal conchal = conchofrontal • Dorsal, ventral and middle conchal • Maxillary • Rostal and caudal • Important relationship with the molar cheek teeth • Sphenopalatine

17. Frontal Sinus Caudal Maxillary Sinus Rostral Maxillary Sinus Dyce et. al

18. Equine Sinuses • Normally air-filled on radiographs • Fluid or a soft tissue mass can be seen • Air-fluid lines • Hard to tell if one or both sides are affected • Maxillary sinus • PM4, M1, M2, M3 tooth roots in sinus • Tooth root infections can easily cause sinusitis

19. Sinuses • A = frontal • B = dorsal conchal • C = stylohyoid bone • D = maxillary sinus D

20. Sinuses • A - Nasal bone • B - Frontal sinus • C - Dorsal conchal sinus • D - Maxillary sinus • E - Mandible

21. Post-op Tooth Repulsion

22. Guttural Pouches • Ventral diverticulum of the auditory tube • Paired; lateral and medial compartments • Superimposed and air-filled on radiographs • Dorsal pharyngeal wall separates the ventral wall of the GP from the pharynx • Stylohyoid bones can be seen through the air filled GP’s • Retropharyngeal lymph nodes • Caudal to the GP • Infection can spread from LN to GP

23. Guttural Pouches

24. A B A = Petrous Temporal Bone B = Basioccipital bone C = Coronoid Process of the Mandible C

25. Basisphenoid / Basiocciptal Fractures • Occur primarily in young horses that flip over backward • Poll strikes against ground • Clinical signs depend upon amount of displacement • Minimal = usually recover but may have residual head tilt • Severe = cerebral hemorrhage and death • If horse can stand, death is not likely

29. Pharynx / Larynx • Pharynx • Where nasopharynx and oropharynx join • Epiglottis • Dorsal to the soft palate • Larynx • Made up of many cartilages which are rarely seen and their location is approximated anatomically on the radiograph

30. Equine Teeth • Herbivores = hypsodont teeth • Continuously erupt to compensate for attrition (wearing) • Grinding surface • Dental enamel is more dense than bone • Sinuses will be very overexposed • Lateral, obliques +/- VD

31. Temporary teeth: 3-0-3 Maxillary 3-0-3 Mandibular “Baby” teeth are shorter and smaller Permanent teeth: 3-1-3(4)-3 Maxillary 3-1-3-3 Mandibular Maxillary premolar 1 is wolf tooth Canine teeth Rudimentary and commonly fail to erupt in mares Equine Dental Formula

32. Dyce et. al

33. Numbering Teeth • Can not definitively tell which side without obliques • Make sure to call them maxillary or mandibular • Always look for wolf teeth

34. Teeth cont. Mandibular 4th premolar = Canine Tooth Incisors

35. P2 P3 P4 M1 M2 M3 P2 P3 P4 M1 M3 M2

37. Tooth root fractures (maxillary molars)

38. Ruminants Horns: - Grow from frontal bones

39. Dental Formula Temporary Teeth: • 0-0-3 Maxillary • 3-1-3 Mandibular Permanent Teeth: • 0-0-3-3 Maxillary • 3-1-3-3 Mandibular

41. Lumpy Jaw(Actinomyces bovis)

43. Test yourself • What structures can you correctly identify?