Short Communication
The Effectiveness of Thermographic Analysis in Equine Orthopedics

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Abstract

One of the main advantages of equine thermography is the detection of subclinical inflammation. The present study was undertaken to determine a specific threshold value of temperature change indicative of subclinical inflammation of the lower parts of the horse's limb. The study involved monitoring 20 racehorses over a period of 10 months. Temperatures of the third metacarpal region were measured every 3 weeks, allowing the average temperature differences to be ascertained between the same areas of forelimbs from the dorsal and palmar aspects in each session. Additionally, ultrasonographic and radiographic standard examinations of lower part of forelimbs were conducted to diagnose any pathological conditions of lower forelimbs. To determine the threshold value of temperature difference the receiver operating characteristic curve method was used, based on thermographic examinations of the same measured area in 20 horses. The threshold value of temperature difference indicative of subclinical inflammation was found to be 1.25°C. In conclusion, thermography can be used as a quick and practical diagnostic tool of subclinical inflammation. These results provide additional support for the continued study of the equine thermography.

Introduction

Traditional diagnosis of equine orthopedic diseases involves radiographic and ultrasonographic examinations. These methods enable diagnosis of anatomical changes caused by inflammation processes [1]. Turner [2] proposed thermography as a complementary diagnostic method enabling abnormal patterns in skin surface temperatures and hence vascularity and metabolic activity within and below the skin surface to be detected. As such, it may be used to detect subclinical inflammation before the onset of clinical signs [3], [4], [5]. Stromberg [6] confirmed the usefulness of this technique in the diagnosis of pathological changes in the superficial digital flexor tendon (SDFT) prior to the appearance of clinical signs of inflammation. In other studies, thermography has been used to diagnose subclinical signs of arthritis [7], [8]. Previous studies [3], [9] also report its use to continuously monitor the distal parts of the limbs and so diagnose subclinical inflammation up to 2 weeks before the onset of clinical lameness and swelling. The present study identified a specific threshold value of temperature change indicative of subclinical inflammation of the lower parts of the horse's limb.

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Study Population and Data Collection

Measurements were obtained from 20 clinically healthy racehorses of two breeds (12 Polish Half Breed; 8 Arabians), 3 years old. All horses were trained for flat racing at Partynice Race Course in Wroclaw, Poland. The study was approved by the Local Ethical Committee for Experiments on Animals of the Wroclaw University of Environmental and Life Sciences. The horses were housed in individual stalls with common management and training regimes. A series of thermographic images were taken of the

Results

Based on ultrasonographic, radiographic, and palpation examinations, horses were divided into two groups, “injured” and “noninjured,” at the end of the research by a veterinarian who was unaware of the thermographic results. The group of “injured” horses included 14 horses with diagnoses of clinical unilateral tendinitis of SDFT (3 horses), unilateral bucked shins (2 horses), bilateral bucked shins (4 horses), unilateral tendon overloads (5 horses), and mechanical injuries (percutaneous trauma;

Discussion and Conclusions

Previous studies have suggested that temperature differences of more than 1°C over 25% of the compared body area in horses is considered to be abnormal [14]. In the present study, a threshold difference value of 1.25°C of temperature change was indicative of subclinical inflammation and was characterized by a high specificity of 0.95%, which allowed identification of 5% of injured horses within the group of noninjured horses. In that case, it could be expected that some forelimbs exceeded the

Acknowledgments

The authors thank Monika Słowik, MSc, Director of Partynice Race Course, for kind permission to carry out the research on racehorses.

References (15)

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