Radiology Packet 42

Navicular/Laminitis

14-year old Arabian Mare“Missy”

• Hx: 5 month history of forelimb laminitis. Lateral radiographs of each forefoot are provided before and after corrective hoof trimming. The radioopaque material on the solar surface and the thumbtacks have been placed to identify the location of the frog. This information will be used for the proper positioning of corrective shoes.

14-year old Arabian Mare“Missy”

• RF– Right fore

• There is mild palmar deviation of the third phalanx with respect to the dorsal hoof capsule.• A large area of gas accumulation is present along the dorsal wall of the hoof. The dorsal solar margin

of the third phalanx is slightly more pointed in shape than normal.

– Left fore• There is a greater degree of palmar deviation of the third phalanx in this foot.• The line of gas indicating laminar separation extends further dorsal than in the right forefoot.• Remodeling of the dorsal solar margin of the third phalanx is present.

– Right fore after corrective hoof trimming• In the right forefoot the excess length of the hoof wall was removed.

– Left fore after corrective hoof trimming• The entire dorsal hoof wall was removed to a level ~ 2cm below the coronary band.• The entire area of the hoof wall that was seperated was removed.

• RD– Bilateral laminitis with palmar deviation of the third phalanx– Laminar separation

11-year old Shetland pony

• Hx: Presented for chronic founder. Single lateral views of the right front and hind feet are available for review.

RHRF

11-year old Shetland pony• RF

– RF• Severe destruction of P3 is present.• The soft tissues dorsal to P3 are massively thickened and distorted.• The limb axis is upright.• The hoof itself is markedly deformed.• There is severe rotation of P3.• There is osteopenia present from minimal weight bearing and the fetlock is swollen.

– RH• The hoof is severely overgrown, the sole is quite thick.• The soft tissue dorsal to P3 measures 13mm proximally, 14mm distally; relative to a P3 length of

56mm, a ratio of P3 thickness to P3 length of 23-25% is obtained. This is within normal limits.

• RD– Severe chronic laminitis with rotation and osteolysis of the RF P3

– Osteomyelitis of P3 could be present

– Severe lack of hoof care of the right hind foot, without laminitis

14-year old Standardbred

• Hx: Horse has been “walking on eggs” for sveral days. The palmar digital pulses are pounding.

14-year old Standardbred

• RF– LF

• Asymmetric thickening of the soft tissues dorsal to P3 and obvious rotation of P3 away from the hoof wall.

• The toe of P3 is flared.

• The distal interphalangeal foot axis is hyperflexed.

• The opaque material on the foot is iodine containing medication

– RF• Changes are similar to that of the LF foot.

• The distal interphalangeal axis is slightly hyperflexed.

• There is an osteophyte found off the dorsoproximal surface of P2.

• RD– Bilateral laminitis with rotation– DJD of the right front proximal interphalangeal joint

13-year old Quarter Horse

• Hx: Lame on the right front foot.

13-year old Quarter Horse

• RF– There is lucency in the cortex of the navicular bone indicating degenerative

changes.– There cortex of the navicular bone is thickened.– A large bone spur is noted laterally on the proximal border of the navicular bone.– Some mineralization is noted in the tendinous structures in this region.– On the navicular view the large lucent defects in the cortex appear as cystic

lesions.

• RD– Navicular osteitis and cystic degeneration

2-year old Standardbred

• Hx: Acutely lame left fore limb. Sound following palmar digital nerve blocks.

2-year old Standardbred

• RF– A linear lucency is present within the navicular bone, lateral of midline.

• RD– Fracture of the left front navicular bone

3-year old quarter horse gelding“Dude”

• Hx: Presented for evaluation of right forelimb lameness. The lameness does not improve with a palmar digital nerve block but is 90% improved with an abaxial sesamoid block. Following the abaxial sesamoid block of the right forelimb the horse becomes lame on the left forelimb.

3-year old quarter horse gelding“Dude”

• RF– Several large synovial invaginations are present on the distal border of the

navicular bone.– In the flexor skyline view the cortex of the navicular bone is slightly thicker than

normal and there is a mild increase in opacity of the medulla of the bone.– Several synovial invaginations are visible. They are of normal size but are

unusually shaped.– Osteophyte formation is present on the extensor process of the third phalanx.

• RD– Degenerative change of the navicular bone– Mild osteoarthritis of the distal interphalangeal joint