A case study of canine juvenile hip dysplasia involving the use of digital thermal imaging. How this tool can enhance patient analysis and treatment.
Gloria, an 11-month-old intact female Rottweiler, was presented for evaluation after a history
of rear limb lameness. Radiography at ten months of age (Figure 1) demonstrated signs of juvenile hip dysplasia: significant abnormalities of the coxofemoral joints with flattening and remodeling of the femoral heads bilaterally, which was more pronounced on the right side along with right coxofemoral subluxation.
Physical exam — The exam confirmed pain and decreased range of motion in the coxofemoral joints, and offloading on the right side.
Physiological screen with digital thermal imaging — The patient was acclimated to room temperature, was not handled during acclimation, and remained calm during image capture. Three digital thermal images were taken with a Digatherm IR 640 unit.
Analysis of the thermal images — Marked thermal asymmetry was evident between the lateral images of the rear limbs. The RH lateral image showed hyperthermia from the hip extending distally, becoming more pronounced over the lateral aspect of the tibia.
The average temperature in Zone 1R, over the right hip, was 85.1°F (29.5°C) (Figure 2). The LH lateral image showed hypothermia radiating cranioventrally from the sacral area.
The average temperature in Zone 1L, over the left hip, was 79.5°F (26.4°C) (Figure 3). The average temperature difference (T) was 37.6°F (3.1°C). This marked difference in temperature represents a physiological hyperthermia on the right side and a physiological hypothermia on the left side. A dorsal thermal image of the lumbar and sacral area showed patchy asymmetrical hypothermia over the right lumbosacral junction and throughout the left caudolateral sacral area (Figure 4).
Interpretation of the thermal images — The thermal images are consistent with radiographic evidence of juvenile hip dysplasia and the symptoms of rear limb lameness.
They support the physical exam findings of pain and decreased range of motion in the coxofemoral joints along with offloading on the right side.
Areas of hyperthermia are noted throughout the thermal image of the right rear leg, which radiographically shows the most severe coxofemoral joint changes. The areas of hypothermia noted in the left lateral and dorsal images are consistent with pain activation of the sympathetic nervous system, which can lead to peripheral vasoconstriction.
Author: Trisha Allie, Bsc, RVT