Thermal imaging of normal and cranial cruciate ligament-deficient stifles in dogs

Application of Infrared Thermography in the Rehabilitation of Patients in Veterinary Medicine

Infrared Thermography (IRT) has become an assistance tool in medicine and is used to noninvasively evaluate heat elimination during and after inflammatory processes or during the recovery period. However, its application in veterinary patients undergoing physiotherapy is a field that requires deep research. This review aims to analyze the application of IRT in the monitoring of animal physiotherapy, using the thermal changes that are present in patients undergoing gait or lameness issues (e.g., inflammation, pain, increased local temperature) as a neurobiological basis. Rehabilitation techniques such as acupuncture, physical therapies, thermotherapy, photo-biomodulation, and electrostimulation have been reported to have an anti-inflammatory effect that decreases the amount of local heat production, which is heat that can be recorded with IRT. Therefore, IRT could be used as a complementary tool to evaluate the effectiveness of the therapy, and it is suggested that further studies evaluate the accuracy, sensibility, and sensitivity of IRT.

Short Communication: Correlation of Thermographic Ocular and Auricular Temperatures with Rectal Temperature in Anesthetized Dogs

Objective

The aim of this study was to determine the correlation of both ocular and auricular thermographic temperatures with rectal temperatures and to determine the advantage of infrared thermography in clinical practice due to its ease of measurement. Animals. This study was designed as a pilot study and conducted on 6 mongrel male dogs during routine castration surgeries at the Kastamonu Municipality Temporary Animal Care Center.

Methods

Rectal temperatures and ocular-auricular thermographic images were taken from 6 dogs anesthetized (xylazine HCl 1 mg/kg and ketamine HCl 15 mg/kg) during routine neutering surgeries. Data were analyzed by Bland-Altman for correlation between rectal-ocular and rectal-auricular temperatures.

Results

Rectal temperatures were significantly higher than orbital and auricular temperatures. In the correlation test, no significant difference and correlation were found between the measurements.

Conclusion

As a result of the study, it was determined that the use of thermography was more advantageous than the waiting times of the digital thermometer used to record rectal temperatures. In addition, the noninvasive nature of thermography increased its acceptability in all dogs. The findings from this pilot study were considered to be at a level that could provide a basis for future studies.

Detection of canine obstructive nasal disease using infrared thermography: A pilot study

Infrared thermography detects variations in heat signature and is utilized in other species to non-invasively identify respiratory disease. This study aimed to determine if infrared thermography could be used to detect nasal disease in dogs. Eight dogs presenting for nasal disease (ND group) and ten healthy control dogs (C group) were enrolled. Dorsal and rostral images of the nose were acquired using a Fluke TiX580 60Hz thermal imaging camera. Images were analyzed using the accompanying software. Regions of interest were defined over the right and left nasal passages to determine the maximum (max), average (avg), and minimum (min) temperatures. Temperatures were compared between ND and C groups, and correlation to disease state (ND or C) was evaluated. Temperature differences and imaging patterns were subjectively compared with diagnosis based on computed tomography (CT) and histopathology. The ND group consisted of 5 spayed females and 3 neutered males. Clinical sings included unilateral epistaxis (n = 4); bilateral serous discharge and sneezing (n = 1); bilateral mucopurulent discharge, epistaxis, and sneezing (n = 1); unilateral mucoid discharge, epistaxis and sneezing (n = 1); and sneezing and unilateral epistaxis (n = 1). Temperatures were significantly different between ND and C groups on dorsal (max p = <0.001, avg p = 0.001, min p = <0.001) and rostral (max p = <0.001, avg p = <0.001, min p = 0.005) images. Temperature positively correlated to disease status (ND vs C group) in both dorsal and rostral images. Subjective analysis of images allowed correct identification of abnormal or normal 27/36 times. Obstructive nasal disease results in a local temperature increase in the affected nasal passage that can be non-invasively detected by infrared thermography.

Evaluation of the thermographic response of the lumbar region in dogs with bilateral hip osteoarthritis

Infrared thermography is suggested as a method of medical assistance for evaluating anatomical regions where there may be some inflammatory or painful condition that requires immediate medical attention. For this reason, this study aimed to characterize digital thermography of the lumbar region in police working dogs with hip osteoarthritis, 47 dogs with bilateral hip osteoarthritis were evaluated. A thermographic dorsoventral view of the dogs' backs were obtained, and mean and maximum temperatures were determined. In addition, results from the Canine Brief Pain Inventory, Liverpool Osteoarthritis in Dogs (LOAD), the Canine Orthopedic Index, and weight-bearing distribution evaluation were collected. Results were compared with an Independent Samples T-Test or ANOVA, followed by an LSD post hoc. Multiple regression was run to predict temperatures from age, sex, breed, body weight, and Orthopedic Foundation for Animals hip score and to predict clinical metrology scores and weight-bearing distribution results from temperature results. The sample included 28 males and 19 females, with a mean age of 6.3 ± 2.5 years and bodyweight of 26.9 ± 5.1 kg, with osteoarthritis hip scores of mild (70.2%), moderate (21.3%), and severe (8.5%). Significant differences were observed in mean temperatures between German Shepherd Dogs (GSD) and Labrador Retrievers (LR) (p < 0.01), and LR and Belgian Malinois (BM) (p=0.02). Mean temperature contributed to the prediction of LOAD and stiffness. LR showed significantly higher temperature values than GSD and BM. No differences were observed between osteoarthritis hip scores and mean temperature values contributed to LOAD scores' prediction. This relation needs to be addressed in further studies, involving a larger number of animals, and to determine changes in response to treatment.

Assessment of Pain and Inflammation in Domestic Animals Using Infrared Thermography: A Narrative Review

Pain assessment in domestic animals has gained importance in recent years due to the recognition of the physiological, behavioral, and endocrine consequences of acute pain on animal production, welfare, and animal model validity. Current approaches to identifying acute pain mainly rely on behavioral-based scales, quantifying pain-related biomarkers, and the use of devices monitoring sympathetic activity. Infrared thermography is an alternative that could be used to correlate the changes in the superficial temperature with other tools and thus be an additional or alternate acute pain assessment marker. Moreover, its non-invasiveness and the objective nature of its readout make it potentially very valuable. However, at the current time, it is not in widespread use as an assessment strategy. The present review discusses scientific evidence for infrared thermography as a tool to evaluate pain, limiting its use to monitor acute pain in pathological processes and invasive procedures, as well as its use for perioperative monitoring in domestic animals.

Applicability of thermography for cancer diagnosis in small animals

Medical thermography is an imaging test used to monitor skin surface temperature. Although it is not a recent technique, significant advances have been made since the 2000s with the equipment modernization, leading to its popularization. In cancer diagnosis, the application of thermography is supported by the difference in thermal distribution between neoplastic processes and adjacent healthy tissue. The mechanisms involved in heat production by cancer cells include neoangiogenesis, increased metabolic rate, vasodilation, and the release of nitric oxide and pro-inflammatory substances. Currently, thermography has been widely studied in humans as a screening tool for skin and breast cancer, with positive results. In veterinary medicine, the technique has shown promise and has been described for skin and soft tissue tumors in felines, mammary gland tumors, osteosarcoma, mast cell tumors, and perianal tumors in dogs. This review discusses the fundamentals of the technique, monitoring conditions, and the role of thermography as a complementary diagnostic tool for cancer in veterinary medicine, as well as future perspectives for improvement.

Effect of a single intra-articular administration of stanozolol in a naturally occurring canine osteoarthritis model: a randomised trial

Osteoarthritis (OA) is a disease with a high negative impact on patient’s quality of life and a high financial burden. It is a source of chronic pain and affects all mammals, including humans and dogs. As the dog is a common model for translation research of human OA, and exploring spontaneous dog OA can improve the health and well-being of both humans and dogs. To describe the effect of the intra-articular administration of stanozolol in a naturally occurring canine OA model, forty canine (N = 40) hip joints were randomly assigned to receive stanozolol or saline (control). On treatment day and at 8, 15, 30, 90, and 180 days post-treatment, several evaluations were conducted: weight distribution, joint range of motion, thigh girth, digital thermography, and radiographic signs. Also, synovial fluid C-reactive protein and interleukin-1 levels were evaluated. Results from four Clinical Metrology Instruments was also gathered. Results were compared with Repeated Measures ANOVA, with a Huynh–Feldt correction, paired-samples t-test, or Wilcoxon signed-rank test, with p < 0.05. OA was graded as mild (90%), moderate (5%), and severe (5%), including both sexes. They had a mean age of 6.5 ± 2.4 years and a bodyweight of 26.7 ± 5.2 kg. No differences were found between groups at treatment day in all considered evaluations. Weight distribution showed significant improvements with stanozolol from 15 days (p < 0.05) up to 180 days (p < 0.01). Lower values during thermographic evaluation in both views taken and improved joint extension at 90 (p = 0.02) and 180 days (p < 0.01) were observed. Pain and function scores improved up to 180 days. In the control group, radiographic signs progressed, in contrast with stanozolol. The use of stanozolol was safe and produced significant improvements in weight-bearing, pain score, and clinical evaluations in a naturally occurring canine OA model.

Thermographic Evaluation of the Duration of Skin Cooling After Cryotherapy in Dogs Following Tibial Plateau Leveling Osteotomy Surgery

Objective

To evaluate the duration of cooling after cryotherapy on the skin over stifle joints in dogs after tibial plateau leveling osteotomy (TPLO) surgery using thermography.

Materials and Methods

Seventeen client-owned dogs of various breeds were enrolled in the study. Dogs underwent TPLO surgeries, and on the next day, thermal imaging was performed on the operated stifle prior to cryotherapy for baseline. Orthogonal views were repeated at 30-min intervals until the skin over the stifle had thermally equilibrated. An ice pack was applied for 20 min on the medial and lateral aspects of the stifle. Each stifle was then re-imaged every 15 min for the first 60 min then every 30 min subsequently until the temperature was within 1°C of the pre-cryotherapy temperature.

Results

Mean skin temperature of the medial view showed no significance difference compared to baseline value at 45 min after cryotherapy was discontinued and after 60 min for the lateral and cranial views. Mean skin temperature was overall higher in the medial view compared to the lateral and cranial during the rewarming period (except immediately after cold application). Mean skin temperatures of all views combined showed a significant decrease in temperature during cryotherapy application, with a slow increase until a plateau was reached after 45 min of rewarming.

Conclusions and Clinical Relevance

Dogs undergoing TPLO for cranial cruciate ligament injury showed quicker rewarming period of superficial tissues compared to previous studies. Cryotherapy is a beneficial modality to reduce superficial tissue temperature in dogs undergoing TPLO, acknowledging that these dogs may require more frequent cryotherapy post-operatively due to more rapid rewarming time compared to dogs without surgery.

Moving Beyond the Limits of Detection: The Past, the Present, and the Future of Diagnostic Imaging in Canine Osteoarthritis

Osteoarthritis (OA) is the most common orthopedic condition in dogs, characterized as the chronic, painful end-point of a synovial joint with limited therapeutic options other than palliative pain control or surgical salvage. Since the 1970s, radiography has been the standard-of-care for the imaging diagnosis of OA, despite its known limitations. As newer technologies have been developed, the limits of detection have lowered, allowing for the identification of earlier stages of OA. Identification of OA at a stage where it is potentially reversible still remains elusive, however, yet there is hope that newer technologies may be able to close this gap. In this article, we review the changes in the imaging of canine OA over the past 50 years and give a speculative view on future innovations which may provide for earlier identification, with the ultimate goal of repositioning the limit of detection to cross the threshold of this potentially reversible disease.

Diferentes métodos de processamento de imagens termográficas para avaliação da temperatura do carpo em bezerros saudáveis

Resumo Este estudo objetivou comparar três métodos de processamento de imagens termográficas na avaliação da temperatura do carpo de bezerros saudáveis. Adicionalmente, buscou-se avaliar a simetria térmica entre os carpos contralaterais desses bezerros. Foram obtidas imagens termográficas de ambos os carpos de oito bezerros, hígidos, com idade entre 20 e 45 dias e peso médio de 38,65 ± 2,27 kg. As imagens foram analisadas por meio do software GRAYESS® IRT Analyzer 7, que possibilitou a obtenção da temperatura total (Ttot), temperatura da região de interesse (Troi) e temperatura máxima média (Tmax). Não houve diferença entre as temperaturas obtidas pelos métodos Ttot e Troi. O Tmax mostrou temperaturas mais elevadas (p < 0,01) em comparação aos demais métodos. Os três métodos de processamento de imagens apresentaram correlações elevadas e significativas para a temperatura dos carpos direito e esquerdo de bezerros saudáveis, entretanto, o Tmax apresentou maior coeficiente de correlação (r = 0,99), o que sugere maior sensibilidade para identificação de variações térmicas entre os carpos contralaterais. O intervalo de confiança de 99% para a diferença de temperaturas entre os carpos direito e esquerdo (∆d-e) foi de 0,03 a 0,26ºC, o que indica que a variação de temperatura dentro desse intervalo não remete a alteração patológica.

Different methods of processing thermographic images to evaluate the carpal temperature of healthy calves

Abstract The aim of this study was to compare three methods of processing thermographic images for the evaluation of carpal temperature in healthy calves. Additionally, we sought to evaluate the thermal symmetry between the contralateral carpi of these calves. Thermographic images were obtained from both carpi of eight healthy calves aged between 20 and 45 days with a mean weight of 38.65 ± 2.27 kg. Using GRAYESS® IRT Analyzer 7 software, the total temperature (Ttot), region-of-interest temperature (Troi), and maximum mean temperature (Tmax) were determined. There was no difference between the temperatures obtained by the Ttot and Troi methods. Tmax showed higher temperatures (p < 0.01) than the other methods. The three image processing methods showed high and significant positive correlations for the temperature of the right and left carpi of healthy calves. Tmax presented a higher correlation coefficient (r = 0.99) than the two other methods, which suggests a greater sensitivity for identifying thermal variations among the contralateral carpi. The 99% confidence interval for the difference between the temperatures of the right and left carpi (∆r-l) was between 0.03 and 0.26°C; thus, a temperature variation within that range does not refer to pathologic processes.

Use of Infrared Thermography during Ejaculation Process and Its Link with Semen Quality and Freezability in Dogs

Simple Summary

Scientific attention to infrared technology has grown over the last decade. Remote and non-invasive monitoring techniques are of great importance in discovering ejaculation response and future trends because of their role in vascular flux regulation. However, detailed information about its use in andrology has yet to be fully explained. Therefore, we aimed to reveal information about the amount of sperm to be obtained by observing stress levels with non-invasive eye temperature measurement, and the relationship between various reproductive temperature patterns and parameters of the animal’s various physiological conditions such as age, body condition, total ejaculation time and testicular volume.

Abstract

This study aimed to describe the thermal variation of external reproductive tracts during ejaculation in relation to sperm quality in dogs. Forty-six adult fertile dogs were monitored using a thermal camera before, during and after the semen collection, taking into account penile and scrotal temperatures as reproductive thermal patterns while eye and perianal temperatures were recorded as complementary thermal patterns of behavioral response. The parameters were classified depending on age (≤4 years and >4 years), body weight (BW) (≤75 kg and >75 kg), sperm concentration (CON) (≤300 million and >300 million), total testicular volume (TTV) (≤600 cm³ and >600 cm³) and total ejaculation time (TET) (≤800 s and >800 s) of the animals from which semen was collected successfully. Heavier males (p < 0.05) that have more consistent testicles (p < 0.01) as well as quicker ejaculate responders (p < 0.001) and lower scrotal temperature had better semen (Δ motility) freezability. The lower eye temperature prior to the ejaculation (p < 0.01), lower scrotal temperature following ejaculation (p < 0.01), and conversely, higher penile temperature during the ejaculation (p < 0.001) had a higher sperm concentration. Furthermore, the sperm freezability was negatively correlated with total ejaculation time (r = −0.39, p < 0.05) and sperm abnormalities were lower in the ejaculate of dogs having a higher temperature of the scrotum, bulbus and penis. In conclusion, infrared monitoring throughout semen collection in dogs can provide information on behavioral reactions during human manipulation, as well as semen quality and testicular functionality.

Changes in Body Surface Temperature Associated with High-Speed Treadmill Exercise in Beagle Dogs Measured by Infrared Thermography

Simple Summary

Heat exchange between the body surface and the external environment plays an important role in the regulation of body temperature in animals. Previous studies on the effect of exercise on the distribution of body surface temperature in dogs have been conducted on a variety of breeds and did not employ specific defined regions of interest. The aim of our research was to assess the influence of high-speed treadmill exercise on body surface temperature using infrared thermography in selected body regions of healthy Beagle dogs, taking into account gait and recovery time. The study was based exclusively on the Beagle breed, which presents short, uniform, and straight hair, conducting heat more readily from the skin. Statistical analysis indicated the highest temperature at the upper forearm and thigh, and the lowest on the croup, back, and neck. The peak surface temperature values in all examined areas were observed after the canter and the post-gallop walk, and the lowest were observed 2 h after exercise. Our study confirms that the body surface temperature of Beagle dogs is influenced by high-speed physical exercise on a treadmill as a result of muscle activity and changes in blood flow. The proximal forelimb and hindlimb were the most influenced by exercise.

Abstract

Evaluation of body surface temperature change in response to exercise is important for monitoring physiological status. The aim of the study was to assess the influence of high-speed treadmill exercise on body surface temperature using infrared thermography (IRT) in selected body regions of healthy Beagle dogs, taking into account gait and recovery time. Thermographic images of the dogs were taken before exercise (BE), after walk (AW), after trot (AT), after canter (AC), just after second walk (JAE), 5 min after exercise (5 AE), 15 min after exercise (15 AE), 30 min after exercise (30 AE), 45 min after exercise (45 AE), and 120 min after exercise (120 AE). Body surface temperature was measured at the neck, shoulder, upper forearm, back, chest, croup, and thigh. Statistical analysis indicated the highest temperature at the upper forearm, shoulder, and thigh, and the lowest on the croup, back, and neck. The peak values of surface temperature in all ROIs were at AC and JAE and the lowest at 120 AE. The study demonstrated that body surface temperature was influenced by high-speed physical exercise on a treadmill and IRT was a viable imaging modality that provided temperature data from specific body regions. The proximal forelimb and hindlimb were the most influenced by exercise.

Evaluation of digital thermography imaging to assess and monitor treatment of police working dogs with naturally occurring hip osteoarthritis

BACKGROUND

In dogs, thermal imaging has been documented only recently, but a growing interest in this modality has led to studies using thermography to assess pathologies in the canine hip, stifle, elbow, intervertebral disc, and bone neoplasia. This study aimed to evaluate the use of digital thermography in assessing and evaluating treatment response in dogs with hip osteoarthritis (OA) and comparing its results with an objective measure and two clinical metrology instruments. In an experimental, randomized, double-blinded study, one hundred hip joints of fifty police working dogs with bilateral hip OA were evaluated. A dorsoventral and lateral thermographic image were obtained on days 0, 8, 15, 30, 90, and 180. Mean and maximal temperatures were determined. Additionally, the animal's weight-bearing distribution and radiographic examination of the hip joint (extended legs ventrodorsal view) were performed. Copies of the Canine Brief Pain Inventory (CBPI) and Canine Orthopaedic Index (COI) were obtained. Results were analyzed by ANOVA, followed by an LSD post-hoc test, and correlations were assessed with Spearman correlation coefficient, with p < 0.05.

RESULTS

Values recorded on the lateral view were higher than those on the dorsoventral view. No differences or correlations were found between Orthopedic Foundation for Animals hip grades and temperature. Digital thermographic images showed a weak significant correlation with weight-bearing evaluations (r = 0.13, p < 0.01) and different clinical metrology instruments scores (r = - 0.25, p < 0.01 for pain severity score, and r = - 0.21, p = 0.04 for gait). It also correlated with radiographic findings, specifically the circumferential femoral head osteophyte and caudolateral curvilinear osteophyte.

CONCLUSION

To our knowledge, this is the first study presenting the digital thermography assessment of Police working dogs submitted to treatment for hip OA. Digital thermography, mainly based on a lateral view evaluation, showed a weak significant correlation with stance analysis and clinical metrology instruments scores.

Superficial Heating Evaluation by Thermographic Imaging before and after Tecar Therapy in Six Dogs Submitted to a Rehabilitation Protocol: A Pilot Study

Thermography is a non-invasive diagnostic method commonly used to monitor changes of the body surface temperature potentially induced by different conditions such as fever, inflammation, trauma, or changes of tissue perfusion. Capacitive-resistive diathermy therapy (such as energy transfer capacitive and resistive-Tecar) is commonly used in rehabilitation due to its diathemic effect secondary to blood circulation increase that could accelerate the healing process. The aim of this study was to monitor by thermal camera the diathermic effects induced by Tecar on the surface of the region of application. The investigation was conducted on six dogs referred for Tecar therapy to treat muscle contractures (three dogs) or osteoarthritis (three dogs). Eleven anatomical treated regions were recorded. Thermographic images and relative measurements were obtained by each region immediately before (T0), at conclusion (T1), and sixty seconds after the Tecar application (T2). Data were recorded and statistically analyzed. A comparison of temperature differences (maximum, minimum and mean values) between T0 and T1, T0 and T2, and T1 and T2 was performed by ANOVA test with Bonferroni post hoc (p ≤ 0.05). Statistically significant differences were detected for mean temperature between T0 (32.42 ± 1.57 °C) and T1 (33.36 ± 1.17 °C) (p = 0.040) and between T1 and T2 (32.83 ± 1.31 °C) (p = 0.031). Furthermore, there was no significant difference between the mean temperature at T0 and T2, demonstrating that superficial diathermic effect exhausted within 60 s.

Thermographic imaging of police working dogs with bilateral naturally occurring hip osteoarthritis

Background

Digital thermal imaging is a physiologic, non-invasive, contactless, and non-radiating diagnostic tool that can assess a wide range of musculoskeletal conditions, including hip osteoarthritis (HOA). Fifty police working dogs were evaluated to compare the dorsoventral (DV) and lateral (LT) thermographic images in dogs with naturally occurring bilateral HOA. A DV, and left and right lateral LT images were obtained for each animal in six different moments. They were positioned standing in a symmetrical upright position for the DV view. Each image included the area from the last lumbar to the first coccygeal vertebrae. Each LT view was set with the greater trochanter in the centre of the image. Images were taken with a thermographic camera from a distance of 60 cm. Mean and maximal temperatures were recorded, analyzed with ANOVA, dependent samples t-test, and Spearman correlation, with P < 0.05.

Results

Nine hundred images were considered, collected from 30 males and 20 females, with a mean age of 6.5 ± 2.2 years and bodyweight of 26.7 ± 5.3 kg. The overall value recorded on the DV view was 25.3º ± 9.1 and 28.4º ± 2.8 on the lateral view. These were significantly different (P < 0.01) and with a low correlation (r = 0.10, P = 0.03). German Shepard dogs showed significantly lower values on all views than other breeds (P < 0.01), and heavier dogs had higher values on the lateral view.

Conclusions

This is the first study that describes digital thermography's diagnostic use to evaluate working dogs with naturally occurring HOA, comparing two different views. Future studies should address each one's value in the diagnosis and response to treatment of this disease.

Clinical and diagnostic imaging findings in police working dogs referred for hip osteoarthritis

Background

Osteoarthritis (OA) is the most commonly diagnosed joint disease in veterinary medicine, with at least 80% of the cases of lameness and joint diseases in companion animals being classified as OA. Sporting and working animals are more predisposed to develop OA since they are exposed to chronic fatigue injuries, leading to bone and muscular tissue damage and failure, resulting in clinical signs. To characterize the clinical signs and diagnostic findings of Police working dogs presenting with bilateral hip OA at the time of diagnosis. Fifty animals were evaluated with a bodyweight ≥ 15 kg, be older than two years, and without any medication or nutritional supplements for ≥ 6 weeks.

Results

Weight distribution, joint range of motion at flexion and extension, thigh girth, digital thermography, and radiographic signs were collected. Data from different Clinical Metrology Instruments (CMI) were collected: Canine Brief Pain Inventory, Liverpool Osteoarthritis in Dogs, Canine Orthopedic Index, and the Hudson Visual Analogue Scale. Results were compared by breed, age, sex, and Orthopaedic Foundation for Animals hip grades with the Independent Samples T-Test, ANOVA followed by a Bonferroni post hoc test, and Pearson correlation coefficient, with p < 0.05. The sample included 30 males and 20 females, with a mean age of 6.5 ± 2.4 years and a bodyweight of 26.7 ± 5.2 kg. Animals with weight distribution below normal levels had significant variations of joint extension and function scores. This evaluation was the only not correlated with at least one breed. Animals with caudolateral curvilinear osteophyte showed a poorer clinical presentation and worse scores in all considered CMIs. Radiographic changes correlated with age and corresponded to worse CMIs scores and weight distribution. Dutch Shepherd Dogs showed better CMI scores than the other considered breeds.

Conclusions

Police working dogs presented with complaints related to hip OA at an early stage of the disease. Hip scores influenced clinical presentation, with moderate cases showing lower thigh girth and worse pain interference and severity, and function scores than mild cases. Patients with severe OA had lower thermographic evaluations than patients with moderate OA. Age was the primary variable influencing considered CMI scores.

Advances in infrared thermography: Surgical aspects, vascular changes, and pain monitoring in veterinary medicine

One of the main functions of infrared thermography (IRT) consists in detecting temperature changes in organisms caused by variations in surface blood circulation. IRT is a useful tool that has been used mainly as a diagnostic method for various stress-causing pathologies, though recent suggestions indicate that it can be used to assess the block quality of certain body regions. In the field of anaesthesiology, IRT has been applied to brachial and epidural blocks, while in algology, changes in surface blood circulation associated with sympathetic activity have been investigated. Thermography has also been employed to complement pain level scales based on the facial expressions of patients in critical condition, or after surgery. In addition, it has been used as a tool in research designed to evaluate different surgical procedures in human medicine, as in the case of surgical burrs for placing dental implants, where IRT helps assess the degree of heating associated with bone devascularisation, reduction in vascular perfusion as a consequence of stroke, and changes in the autonomous nervous system, or the degree of vascular changes in flaps applied to burn patients. In veterinary medicine, thermography has brought several benefits for animals in terms of evaluating lesions, diseases, and surgical procedures. The aim of this review is to evaluate how IRT can be used as a tool in surgical procedures, cases of vascular change, and pain monitoring in veterinary medicine with an emphasis on small animals.

Medical infrared thermal imaging of syringomyelia in the Cavalier King Charles Spaniel

Background

Medical infrared thermal imaging (MITI) is a non-invasive imaging modality gaining popularity in the veterinary field. An infrared camera captures emission of heat and creates a color map in the form of a thermogram. Topical heat emission is influenced by localized disease processes as a result of autonomic nervous system imbalance. The purpose of this study was to determine the utility of using thermography to identify changes in thermographic patterns associated with syringomyelia (SM) presence or absence in Cavalier King Charles Spaniels (CKCS) with Chiari-like Malformation (CLM).

Results

In CKCS with CLM, MITI was most accurate at a texture distance of 6. Optimizing imaging feature sets produced a highest accuracy of 69.9% (95% CI: 59.5–79.0%), with 81.3% sensitivity and 57.8% specificity for identifying the presence of syringomyelia.

Conclusion

Thermographic image analysis is a successful non-invasive, diagnostic test that can be used to screen for syringomyelia presence in a CKCS with CLM.

Evaluation of Thermographic Imaging in Canine Hindlimb Muscles After 6 Min of Walking-A Pilot Study

Objective: To evaluate changes in superficial temperature of hindlimb muscles before and after a 6-min walk in healthy dogs.

Methods: Two infrared thermographic images were captured of the proximal and distal hindlimbs of 11 healthy dogs before and after a 6-min walk. Orthopedic exam and objective gait analysis confirmed the healthy status of study subjects. Superficial temperatures of the gastrocnemius, biceps femoris, and gracilis were assessed. Analysis of images was performed using 2 different methods of region of interest (ROI) selection. ROI were selected first using one point (single pixel) in the muscle and then separately by selecting a line (LN) corresponding to many points of each muscle belly from which an average was taken. P < 0.05 was considered significant.

Results: There was no significant change in temperature using point ROI before and after 6 min of walking of the gastrocnemius, gracilis, and biceps femoris muscles (p = 0.273, p = 0.349, p = 0.351, respectively). Using linear ROI, both biceps femoris and gracilis muscles exhibited significant increases in temperature (p < 0.0001, p = 0.032, respectively). There was no significant increase in temperature of gastrocnemius muscle for both point and linear ROI selection (p = 0.273, p = 0.448, respectively). The right biceps femoris temperatures were higher compared to left biceps femoris using the linear ROI before and after walks (p < 0.0001). The overall (left and right limbs pooled) standard deviation of point selected values were greater than LN selected values of the biceps femoris (1.35 and 1.11) and gastrocnemius (1.51 and 1.23). In contrast, standard deviation for the gracilis measurements were decreased using point selection vs. LN selection (1.09 and 1.3).

Conclusions: The biceps femoris and gracilis muscles demonstrated significant increases in surface temperature after 6 min of walking using the linear method of ROI. Measurement of numerous points along the entire length of the biceps femoris and gastrocnemius muscles may provide a more accurate assessment of the increased vascularity within the tissues resulting from work compared to single point selection.

Clinical Significance: Prior activity and ROI selection method should be considered when interpreting thermography results.

Medical infrared thermal imaging of canine appendicular bone neoplasia

Background

Medical infrared thermal imaging (MITI) is a noninvasive imaging modality used in veterinary medicine as a screening tool for musculoskeletal and neurological disease processes. An infrared camera measures the surface body heat and produces a color map that represents the heat distribution. Local trauma or disease can impair the autonomic nervous system, which leads to changes in the local dermal microcirculation and subsequent alteration of surface body heat. Disruption of autonomic flow to the cutaneous vasculature at deeper levels can also result in asymmetric thermographic results. The purpose of this study was to evaluate surface temperature differences between limbs affected by bone neoplasia and their normal contralateral limbs.

Results

A statistically significant difference in average temperature was noted between regions of interest of the two groups (paired difference: 0.53 C° ± 0.14; P = 0.0005). In addition, pattern recognition analysis yielded a 75–100% success rate in lesion identification.

Conclusions

Significant alterations noted with average temperature and thermographic patterns indicate that MITI can document discernible changes associated with the presence of canine appendicular bone tumors. While MITI cannot be used as the sole diagnostic tool for bone cancer, it can be used as a screening modality and may be applicable in early detection of cancer.

Clinical and Radiological Evaluation of the Treatment of Cranial Cruciate Ligament Rupture in Cats with the Musculus Biceps Femoris Transposition Technique

The aim of this study was to clinically and radiologically evaluate the technique of biceps femoris muscle transposition as a new extracapsular treatment technique for cranial cruciate ligament ruptures, which are often encountered in cats. In this study, eight cats diagnosed with cranial cruciate ligament rupture were treated with the biceps femoris muscle transposition technique. The postoperative standard clinical examination procedures were applied to each cat for 90 days. In the preoperative clinical and radiological examinations of the eight cats in the study, cranial cruciate ligament rupture alone was diagnosed in seven of them. Both, the cranial cruciate ligament rupture and meniscal lesions in the same stifle joint were determined in one cat. The biceps femoris muscle transposition technique operation took approximately 20 mins in each case.

The postoperative radiographs were taken on days 10, 30, 60 and 90. No complications were seen in any case during the postoperative follow-up. The Illinois University Evaluation Scale was used for a more objective evaluation. At 90 days postoperatively, there was no lameness in seven out of eight cats, and mild limping was determined in one of them due to concomitant meniscal lesion.

According to the study results, the biceps femoris muscle transposition technique was found to be extremely useful as an easily applicable technique in the treatment of cranial cruciate ligament rupture in cats.

Quantifying body surface temperature differences in canine coat types using infrared thermography

Infrared thermography (IRT) has been used to assess the health of canines by measuring surface temperatures. However, little is known about the effect hair coat differences has on expected surface temperature in healthy canines under the influence of hair coat differences. The aim of this study was to identify the influence of coat characteristics in body surface temperature (BST) in canines (Canis lupus familiaris). To determine the changes in BST, an infrared thermal imaging camera (i.e. FLIR B400) was used. Thermal images of the left and right sides of privately-owned dogs (n = 50) were acquired. Each animal acclimated in an indoor environment away from direct sunlight (23 ± 2.0 °C) for 15 min, and images were taken at a distance 0.67 ± 0.24 m. Regions of interest (ROIs) of mean surface temperatures were examined across the lateral surface of each animal. No statistical differences were detected based on laterality (P = 0.08). Mean BSTs were categorized by each dog's hair coat type: short coat (SC), curly coat (CC), long coat (LC), and double coat (DC). These BSTs were then analyzed using two-way analysis of variance, or ANOVA, (Shapiro-Wilk) and pairwise comparison. SC animals had the highest BST (31.77 ± 0.19 °C; P < 0.001) whereas LC (28.14 ± 0.31 °C; P < 0.001) and DC animals (28.25 ± 0.23 °C; P < 0.001) were lower in BST. CC animals portrayed intermediate BST (29.85 ± 0.33 °C; P < 0.001). The Pearson correlation and one-way ANOVA between rectal temperature and BST and coat type were not statistically significant (r = -0.24 and P = 0.07, respectively). Results indicate that short-haired dogs exhibit a more drastic increase in BST (approximately 2 °C) in comparison to other dogs and this should be considered in future clinical applications.

Infrared thermography: a rapid and accurate technique to detect feline aortic thromboembolism

Objectives The objective of this study was to evaluate the diagnostic accuracy of infrared thermography in cats with acute pelvic paralysis to differentiate feline aortic thromboembolism (FATE) from non-ischaemic conditions. Methods Thermographic images were prospectively obtained at admission from cats presented for acute bilateral pelvic paralysis. Based on the final diagnosis, cats were divided into a FATE and a control group (ischaemic and non-ischaemic related pelvic paralysis, respectively). The maximum (Tmax), minimum (Tmin) and average (Tav) temperatures were determined for each of the four limbs within a hand-drawn region of interest on the dorsal limb extremity. Temperature differences between the forelimb (non-affected) and hindlimb (affected) with the highest temperature (ΔT), with the lowest temperature (δT) and from the right and left side (RightΔT and LeftΔT, respectively) were calculated. Results The FATE and control groups included 10 and six cats, respectively. In the FATE group, right hindlimb mean Tmax (23.6°C ± 1.9), left hindlimb mean Tmax (23.6°C ± 2.2) and mean Tav (22.7°C ± 2.2) were significantly lower than in the control group (26.6°C ± 3.5 [ P = 0.042]; 26.6°C ± 2.4°C [ P = 0.024] and 25.7°C ± 2.0 [ P = 0.020], respectively). ΔT, δT, RightΔT and LeftΔT were significantly higher in the FATE group than in the control group. A cut-off value of 2.4°C for RightΔTmax and LeftΔTmax allowed discrimination between the FATE and control groups with a sensitivity of 80% and 90%, respectively, a specificity of 100% for both, a positive predictive value of 100% for both, and a negative predictive value of 75% and 86%, respectively. Conclusions and relevance A minimal difference of 2.4°C between ipsilateral affected and non-affected limbs has an excellent specificity and high sensitivity for FATE diagnosis. Infrared thermography seems to be a promising, useful, easy, non-invasive and rapid method for detecting aortic thromboembolism in cats, particularly in emergency situations.

Medical infrared imaging and orthostatic analysis to determine lameness in the pelvic limbs of dogs

Subtle lameness makes it difficult to ascertain which is the affected limb. A study was conducted to investigate a change in the thermal pattern and temperature of the thermal image of the paw print in a lame pelvic limb compared to a non-lame pelvic limb of dogs confirmed by orthostatic analysis. Fourteen client owned dogs with a unilateral pelvic limb lameness and 14 healthy employee dogs were examined and the pelvic limbs radiographed. Thermal images of the paw print were taken after each dog was kept in a static position on a foam mat for 30 seconds. Average temperatures and thermographic patterns were analyzed. Analysis was performed in a static position. The asymmetry index for each stance variable and optimal cutoff point for the peak vertical force and thermal image temperatures were calculated. Image pattern analysis revealed 88% success in differentiating the lame group, and 100% in identifying the same thermal pattern in the healthy group. The mean of the peak vertical force revealed a 10.0% difference between the left and right pelvic limb in healthy dogs and a 72.4% between the lame and non-lame limb in the lame dog group. Asymmetry index analysis revealed 5% in the healthy group and 36.2% in the lame group. The optimal cutoff point for the peak vertical force to determine lameness was 41.77% (AUC = 0.93) and for MII 0.943% (AUC = 0.72). The results of this study highlight the change in the thermal pattern of the paw print in the lame pelvic limb compared to a non-lame pelvic limb in the lame group and the healthy group. Medical infrared imaging of the paw prints can be utilized to screen for the lame limb in dogs.

Thermal Imaging in Medical Science

Thermal imaging is a non-destructive, non-contact and rapid system. It reports temperature through measuring infrared radiation emanated by an object/ material surface. Automated thermal imaging system involves thermal camera equipped with infrared detectors, signal processing unit and image acquisition system supported by computer. It is elaborated in wide domains applications. Extensive focus is directed to the thermal imaging in the medical domain especially breast cancer detection. This chapter provided the main concept and the different applications of thermal imaging. It explores and analyses several works in the light of studding the thermograph. It is an effective screening tool for breast cancer prediction. Studies justify that thermography can be considered a complementary tool to detect breast diseases. The current chapter reviews many usages and limitations of thermography in biomedical field. Extensive recommendations for future directions are summarized to provide a structured vision of breast thermography.

Medical Infrared Imaging of Normal and Dysplastic Elbows in Dogs

OBJECTIVE

To investigate the ability of medical infrared imaging to differentiate between normal canine elbows and those with abnormal elbows (elbow dysplasia).

STUDY DESIGN

Prospective cohort study.

ANIMALS

Dogs with normal (n = 15) and abnormal (n = 14) elbows.

METHODS

Infrared imaging was performed on all dogs and data analyzed via descriptive statistics and image pattern analysis software. Animals with elbow dysplasia had arthroscopic procedures to confirm the presence of elbow disease.

RESULTS

Computer recognition pattern analysis was up to 100% correct in identifying abnormal elbows and normal elbows, with the medial images most consistent. The caudal, lateral, and cranial images correctly identified 83-100% abnormal elbows. The caudal and lateral images correctly identified 83% normal elbows. A significant difference in temperature was found between normal and abnormal elbows for the cranial full region of interest, lateral images, and each quadrant.

CONCLUSION

Medical infrared imaging was able to correctly identify known abnormal and known normal elbows in dogs.

Medical infrared thermal imaging of cats with hyperthyroidism

OBJECTIVE

To determine the usefulness of medical infrared thermal imaging (MITI) as a screening tool for hyperthyroidism in cats, evaluate the need for hair clipping over the ventral aspect of the neck to achieve optimal images, and determine whether there is a change in thermal patterns at 1 and 3 months after radioactive sodium iodide I 131 treatment.

ANIMALS

17 cats with and 12 control cats without hyperthyroidism.

PROCEDURES

All cats underwent MITI first with the hair present and then after the hair was clipped. Each cat with hyperthyroidism was subsequently appropriately treated SC with radioiodide; reevaluations, including MITI before and after hair clipping and measurement of serum thyroxine concentration, were performed 1 and 3 months after treatment.

RESULTS

The MITI had 80.5% and 87.5% accuracy in differentiating hyperthyroid cats from clinically normal cats before and after the hair over the ventral aspect of the neck was clipped. Among cats with an initial serum thyroxine concentration > 4.0 μg/dL, the success rate for MITI-detected response to radioiodide treatment at the 1-month reevaluation was 92.86% in unshaved cats and 85.71% in shaved cats. The success rate for MITI-detected response to radioiodide treatment at the 3-month reevaluation was 100% in unshaved and shaved cats.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that MITI was successful in differentiating between hyperthyroid cats and clinically normal cats and identifying patients with thyroxine concentration within reference interval after radioactive sodium iodide I 131 treatment.

A comparison of thermographic imaging, physical examination and modified questionnaire as an instrument to assess painful conditions in cats

Pain recognition in cats is difficult and requires a multidisciplinary approach for diagnosis. A total of 103 client-owned cats were enrolled in this prospective, blinded clinical trial. Cats were invited to the clinic, or presented for annual rechecks/vaccinations, or gastrointestinal, dental or locomotor problems. The cats were of different breeds; both shorthaired and longhaired cats were included. Those cats that tolerated it were palpated and all cats were examined with the non-invasive method of thermographic imaging. Owners filled out a questionnaire about their cat's behaviour and estimated whether the cat was in any pain. The agreement between a questionnaire and thermographic imaging or palpation was low. Also, the agreement between the owner's estimation of pain and thermographic imaging or palpation was low. The agreement between palpation and thermographic imaging was moderate, suggesting that thermographic imaging is a potential tool in clinical practice for detecting and screening cats that are, potentially, in pain.

Thermographic imaging of the superficial temperature in racing greyhounds before and after the race

A total of 47 racing greyhounds were enrolled in this study on two race days (in July and September, resp.) at a racetrack. Twelve of the dogs participated in the study on both days. Thermographic images were taken before and after each race. From the images, superficial temperature points of selected sites (tendo calcaneus, musculus gastrocnemius, musculus gracilis, and musculus biceps femoris portio caudalis) were taken and used to investigate the differences in superficial temperatures before and after the race. The thermographic images were compared between the right and left legs of a dog, between the raced distances, and between the two race days. The theoretical heat capacity of a racing greyhound was calculated. With regard to all distances raced, the superficial temperatures measured from the musculus gastrocnemius were significantly higher after the race than at baseline. No significant differences were found between the left and right legs of a dog after completing any of the distances. Significant difference was found between the two race days. The heat loss mechanisms of racing greyhounds during the race through forced conduction, radiation, evaporation, and panting can be considered adequate when observing the calculated heat capacity of the dogs.

Comparison of three thermal cameras with canine hip area thermographic images

The objective of this study was to compare the method of thermography by using three different resolution thermal cameras and basic software for thermographic images, separating the two persons taking the thermographic images (thermographers) from the three persons interpreting the thermographic images (interpreters). This was accomplished by studying the repeatability between thermographers and interpreters. Forty-nine client-owned dogs of 26 breeds were enrolled in the study. The thermal cameras used were of different resolutions-80 × 80, 180 × 180 and 320 × 240 pixels. Two trained thermographers took thermographic images of the hip area in all dogs using all three cameras. A total of six thermographic images per dog were taken. The thermographic images were analyzed using appropriate computer software, FLIR QuickReport 2.1. Three trained interpreters independently evaluated the mean temperatures of hip joint areas of the six thermographic images for each dog. The repeatability between thermographers was >0.975 with the two higher-resolution cameras and 0.927 with the lowest resolution camera. The repeatability between interpreters was >0.97 with each camera. Thus, the between-interpreter variation was small. The repeatability between thermographers and interpreters was considered high enough to encourage further studies with thermographic imaging in dogs.