Thermography-Assisted Diagnosis of a Distal Phalanx Fracture in a Reticulated Giraffe (Giraffa camelopardalis reticulata)
A 10-year-old female reticulated giraffe (Giraffa camelopardalis reticulata) presented with an acute, severe, non-weight bearing lameness of the right forelimb. No swelling or deviations of the limb were noted in visual exam. The animal would not allow palpation of the limb distal to the cubitus. After 4 days of stall rest, no improvement in gait or any signs indicating location of an abnormality were seen. Examination of all legs using a thermographic camera (ThermaCam PM 675, Flir Systems, Wilsonville, Oregon 97070 USA) revealed an increased surface temperature of 0.9°C in the heel bulbs of the right forelimb particularly on the medial side.
Radiographs were obtained 10 days after the original lameness was noted. The animal had been trained to station for radiographs, including lateromedial (LM), dorsopalmar, oblique (dorsolateral-palmaromedial and dorsomedial-palmarolateral) and 45° dorsopalmar. A fracture through the body of the third phalanx of the medial digit was identified only on the LM projection. The fracture was a displaced, complete articular fracture in the frontal plane, dividing P3 into two large fragments. Of note on the radiographs were the sesamoids which are equivalent to 1/3 of the size of the distal phalanx.
The animal was managed with stall rest on a padded floor and treated with etodolac (Taro Pharmaceuticals, Hawthorne, New York 10532 USA; 2.8 g PO every 24 h×28 days). Occasional use of the leg started within 7 days of the original injury and improved gradually. Within 6 weeks, the animal showed virtually no lameness. Follow-up radiographs at 6 and 20 weeks showed increased opacification at the fracture line suggesting progressive healing.
Thermography is a method that measures surface temperatures via infrared emissions. Variations in skin temperature results from changes in tissue perfusion and blood flow in superficial veins.2 Increase in blood flow with produced heat are cardinal signs of inflammation. It is important in thermography to evaluate whole body images and contrasts in temperature between contralateral body parts. Both medical and industrial imaging instruments are capable of differentiating temperature changes of 0.1°C.
In domestic equines (Equus caballus), thermography is particularly useful in diagnosing conditions of the foot, such as laminitis and navicular disease.2 Due to the encasing effect of the hoof wall in horses and cattle physical examination is limited in sensitivity for diagnosis of foot diseases.3
A lack of obvious swelling may have occurred in this case due to the thickness of giraffe skin and unique elasticity of the connective tissue. Cardiovascular dynamics in a giraffe are complex and high extra vascular tension must be needed in the distal limbs to maintain sufficient hydrostatic pressure to prevent pooling of fluid and adequate venous return.
In zoo and wildlife patients, palpation and other direct diagnostic techniques are frequently difficult. Sometimes close contact can be achieved with training; however, the process may be long. Diagnosis via remote, noninvasive methods such as thermography should be considered for any larger animal where size and behavior make management a challenge.1
We commend the Binder Park Zoo Animal Care staff for dedication to the giraffe operant conditioning program.
1. Kouba, A., and S. Willard. 2005. What’s new and hot in zoo technology: thermography? AZA Communiqué: 10–13.
2. Turner, T.A., R.C. Purohit, and J.C. Fessler. 1986. Thermography: a review in equine medicine. Comp. Cont. Educ. Pract. Vet. 8(11): 855–861.
3. Vaughan, L.C., and M.A.R. Osman. 1967. Fracture of the third phalanx in cattle. Vet Rec. 80(18): 537–543.