Diagnostic Imaging of Horses LACP Chapter 7 Pages 147-175

Diagnostic Radiology Very similar to small animals Principles are the same as in small animals Large animal radiology is very unique due to the conformation of the patient and the fact that most radiographs are performed on a standing, awake patient. The temperament of the animal can hinder the ability to position a patient for ideal film studies.

Safety: “Fear Factors” Injured horses-painful Strange noises Strange things touching the horses; for example, ideally the film cassette should be placed to contact the patient’s skin. Personnel and equipment are in vulnerable positions with a patient that is often suspicious of the situation.

Safety: Personnel Involved Move slowly and speak in a low calm voice Do not make loud crashing noises Let the horse know that you are getting ready to do something to him/her. Gently rub the area of interest-touch it lightly if it is not injured. PPE-Wear these items! What are they?

Just how many people does it take to take a radiograph? One person to tend to the horse’s head-your restrainer One person to operate the radiograph machine One person to hold/position the film cassette That’s right-this equals 3

Anatomic Direction Femur - tibia/fibula Tarsus - digits Cranial - Caudal Tarsus - digits Dorsal - Plantar

The five Routine views Lateromedial (Lateral)--Extended Lateromedial (Flexed lateral)--Flexed Dorsopalmar (DP) Dorsolateral-palmaromedial oblique (DLPMO) Dorsomedial-palmarolateral oblique (DMPLO)

Radiograph labeling Standard convention Marker is placed Cranial / Dorsal Lateral Be sure to “flash” the cassette Permanently identifies film as belonging to a certain patient Owners name Patient name / number Name of clinic / Location Date of exam Limb examined (RF, LF, RH, LH)

The Equipment: Radiograph machine Caliper Radiograph cassette holder Cassette/film Play-doh or putty Positioning blocks Processor to develop the film Chemical Sedation/Restraint devices PPE Time and patience!

Radiograph Cassette holder

Film cassette in cassette holder

Portable radiograph machine

Portable radiograph machine

Portable radiograph machine with a light collimator

Wood and Plexiglas positioning block for the equine foot.

Position of the cassette for stand-on radiographic views

Position of the foot and cassette for stand-on views of the foot.

Slots provide additional support for film cassettes.

Packing of the grooves of the sole to prevent artifacts created by the air pockets of the hoof. These artifacts can sometimes mimic fracture lines and may obscure true lesions. Do not over pack. Always be sure to clean the hoof wall, sole and recesses of the frog. Hoof picks, soap, water and a brush may be needed.

Here’s the setup! Without the horse of course…

Generally you are about 30-40 inches (80 cm.) away from the patient.

Removal of the shoe is recommended but is expensive to remove and place back on the horse. Many owners will object to this. Always obtain owner consent before removing shoes!

Horseshoes interfere with interpretation of radiographs

Hoof anatomy

Lateral Horse is weight bearing Cassette holder is used X-ray beam is perpendicular to the middle carpal joint

Flexed Lateral Foot is elevated Carpus held in flexion X-ray beam is centered at middle carpal joint Tendency to shift carpus toward midline Hands are close enough for scatter radiation--use gloves!

Dorsopalmar Weight bearing X-ray beam centered at middle carpal joint Cassette parallel to the palmar aspect of the limb