PMC5608963_01
Appearance of a Thoroughbred horse with chronic laminitis.
jes-28-105-g001.jpg
PMC5608963_01_jes-28-105-g001.jpg
fig_001
Thoroughbred mare with a body weight of 443 kg and body condition score based on Texas A&M University Equine Body Condition Score of 3, presented increased bilateral forelimb hoof temperature, prominent digital pulse, and a history of severe lameness for 25 months (Fig. 1). This horse had been treated with shoeing therapy.
Mid-sagittal section in the left forelimb (left, MRI; center, CT; right, radiograph). There was moderate joint fluid distention in the distal inter phalangeal joint capsule (a), a heterogenous signal intensity in the laminar corium (b), a wavy dorsal aspect of the laminar corium (c), loss of the dorsal aspect of the cortical bone of the 3rd phalanx (d), and an increased signal intensity extending through the deep digital flexor tendon (e).
jes-28-105-g002.jpg
PMC5608963_01_jes-28-105-g002.jpg
fig_002
In the left forelimb, there was moderate joint fluid distension in the distal interphalangeal joint capsule (Fig. 2a), a heterogeneous signal intensity in the laminar corium (Fig. 2b), a wavy dorsal aspect of the laminar corium (Fig. 2c), loss of the dorsal aspect of the cortical bone of P3 (Fig. 2d), and an increased signal intensity extending through the deep digital flexor tendon (Fig. 2e).
Mid-sagittal section in the right forelimb (left, MRI; center, CT; right, radiograph). There was a reduced amount of fluid in the distal inter phalangeal joint capsule (a), a high signal intensity in the dorsal cortex in the extensor process (b), a heterogeneous signal intensity in the laminar corium (c), and an increased signal intensity extending through the deep digital flexor tendon (d). Sclerosis (e) was evident as an area of low signal intensity on MRI and an area of high density on CT. Hoof wall separation that was identifiable on CT (f) but not on MRI.
jes-28-105-g003.jpg
PMC5608963_01_jes-28-105-g003.jpg
fig_003
In the right limb, which was also severely affected, there was reduced amount of fluid in the distal interphalangeal joint capsule (Fig. 3a), a high signal intensity in the dorsal cortex of the extensor process (Fig. 3b), a heterogeneous signal intensity in the laminar corium (Fig. 3c), and an increased signal intensity extending through the deep digital flexor tendon (Fig. 3d). Also, sclerosis (Fig. 3e) was imaged as an area of low signal intensity on MRI, whereas it was imaged as an area of high density on CT. Hoof wall separations were identified on CT (Fig. 3f) but not on MRI because of lower proton density in the hoof.
Mid-sagittal section in the right forelimb (left, T2-weighted image; right, T1-weighted image). There was an area of low signal intensity in both the T1-weighted image and T2-weighted image in the distal interphalangeal joint capsule (a) and a heterogeneous signal intensity in the perioplic corium (b).
jes-28-105-g004.jpg
PMC5608963_01_jes-28-105-g004.jpg
fig_004
T1-weighted images and T2-weighted images in the distal interphalangeal joint capsule (Fig. 4a), which suggested chronic hemorrhage. There was also an area of heterogeneous signal intensity in the perioplic corium (Fig. 4b).
Extracted 3-dimensional 3rd phalanx. The measured volume was 53.7 cm3 in the right limb and 63.1 cm3 in the left.
jes-28-105-g005.jpg
PMC5608963_01_jes-28-105-g005.jpg
fig_005
There was a difference in the volume of P3 when comparing the right (53.7 ml3) and left (63.1 ml3) sides in volume rendering 3D images measured by an image-processing workstation (Fig. 5).
Three-dimensional venogram (lateromedial view). Heel vessels were observed in both the right and left forelimbs (a), but there was a difference in the vasculature of the coronary plexus (b) and circumflex vessels (c) between the right and left forelimbs. The right limb showed more reduction than the left.
jes-28-105-g006.jpg
PMC5608963_01_jes-28-105-g006.jpg
fig_006
In the 3D venogram, heel vessels were visualized in both the right and left forelimbs (Fig. 6a), although there was a difference in the vasculature of the coronary plexus (Fig. 6b) and circumflex vessels (Fig. 6c) between the right and left limbs.
Gross examination of the laminar layer of the medium hoof wall in a sagittal section and histopathology. The bony deformity in the sagittal section was consistent with both MRI and CT. An ectopic white band tissue, an abnormal horny structure called a lamellar wedge, was continuously observed in the regenerated epidermal lamina (Hematoxylin-eosin stain, bar=1 mm).
jes-28-105-g007.jpg
PMC5608963_01_jes-28-105-g007.jpg
fig_007
Laminitis was confirmed by pathological examination (Fig. 7).