961045
JFM
Journal of Feline Medicine and SurgeryNitrini et al
Original Article
Thermographic assessment of skin
and soft tissue tumors in cats
Andressa Gianotti Campos Nitrini , Bruno Cogliati
and Julia Maria Matera
Journal of Feline Medicine and Surgery
2021, Vol. 23(6) 513­–518
© The Author(s) 2020
Article reuse guidelines:
sagepub.com/journals-permissions
https://doi.org/10.1177/1098612X20961045
DOI: 10.1177/1098612X20961045
journals.sagepub.com/home/jfm
This paper was handled and processed
by the American Editorial Office (AAFP)
for publication in JFMS
Abstract
Objectives This study set out to determine the average temperature of skin and soft tissue tumors in cats using
infrared thermography and to investigate correlations between thermographic findings and tumor type. Correlations
between thermographic findings, histologic subtype and tumor grade were also investigated in cases of feline
injection site sarcoma (FISS).
Methods Thermographic images of normal skin and skin overlying neoplastic lesions were prospectively
obtained. Following thermographic assessment, tumors were resected and submitted to histopathologic and
immunohistochemical analysis. Mean temperatures detected in tumoral areas were compared between different
tumor types and between FISSs of different histologic subtypes and grades.
Results Thermograms obtained from 11 healthy cats and 31 cats presenting with skin and soft tissue tumors
(eight benign and 23 malignant tumors, including 21 FISSs) were evaluated in this study. Thermal behavior varied
widely in normal skin, as well as in skin overlying neoplastic lesions. Mean temperatures were significantly higher in
malignant compared with benign tumors (35.4 ± 1.8ºC and 34.5 ± 1.7ºC respectively; P = 0.01), with a temperature
above 34.7ºC being associated with malignancy (sensitivity 76%, specificity 80%; P = 0.01). Temperatures detected
in FISS did not differ significantly according to histologic subtype (P = 0.91) or tumor grade (P = 0.46), or between
primary and recurring tumors (P = 0.25).
Conclusions and relevance Infrared thermography proved to be a sensitive and effective method for detection
of temperature differences between malignant and benign skin and soft tissue tumors in cats. Thermographic
assessment may contribute to diagnosis and prognostic estimation in feline oncologic patients.
Keywords: Thermographic image; thermography; infrared; feline injection site sarcoma; soft tissues; tumor
Accepted: 31 August 2020
Introduction
Infrared thermography, or thermal imaging, is a simple,
painless, non-invasive, non-ionizing diagnostic imaging technique that estimates skin surface temperature
based on infrared radiation emanating from the body.1
Thermography is used as an ancillary modality for diagnosis and follow-up of several disorders, including vascular, neurologic, orthopedic and neoplastic diseases, or
any other condition involving changes in body surface
temperature.2–7
In oncology, thermographic assessment is based on
the premise that increased tumor blood flow, angiogenesis and metabolic rates will translate into higher temperatures in tumoral vs healthy surrounding tissues.
Temperature gradient detection may assist in tumor identification, grading and follow-up.4,8 If used continuously
over the course of treatment, thermography may help
monitor tumor responses, as local temperature tends to
decrease in response to therapy-induced tissue damage.
Such metabolic (and hence thermographic) changes may
precede tumor shrinking, allowing for early assessment
of response to therapy.1 Dynamic thermography, a modification of standard thermography, entails application of
Department of Surgery, University of São Paulo, Faculty of
Veterinary Medicine and Animal Science, São Paulo, Brazil
Corresponding author:
Andressa Gianotti Campos Nitrini DVM, MSc, PhD, Department
of Surgery, University of São Paulo, Faculty of Veterinary
Medicine and Animal Science, Av Prof Orlando Marques
de Paiva, 87, CEP, São Paulo, SP 05508-270, Brazil
Email: gianotti@usp.br
514
thermal stimuli prior to local temperature measurement
to induce higher temperature gradients between diseased
and surrounding tissues, so as to increase accuracy.9
In contrast to the large number of studies in humans
and dogs,10,11 thermographic assessment of feline neoplastic diseases, including feline injection site sarcoma
(FISS; a malignant mesenchymal tumor developing at
sites of injection of vaccines and other products), has
seldom been reported.12
This study set out to determine the average temperature
of feline skin and soft tissue tumors, and to investigate
correlations between thermographic findings and histologic diagnosis following surgical resection. Correlations
between tumor temperature, tumor grade and histologic
subtype were also investigated in cases of FISS.
Materials and methods
Thermographic assessment
This study was approved by the Ethics Committee of
the Faculty of Veterinary Medicine and Animal Science,
University of São Paulo – FMVZ-USP (protocol number 29
40110715/2016). Owner consent was obtained in all cases.
The sample comprised 11 healthy cats (control group)
and 31 cats presenting with skin or soft tissue masses
(tumor group) referred to the Service of Small Animal
Surgery, Surgery Department of FMVZ-USP between
July 2015 and July 2019, regardless of breed, sex or age.
Tumors were characterized according to size (measured
with handheld calipers), location and history of recurrence. Healthy cats with no history of disease were used
as controls for thermal characterization of normal feline
skin (control group). Rectal temperature was measured
in all cats using a digital rectal thermometer. Only those
with normal body temperatures were included in the
study (temperature ranging from 36.7°C to 38.9°C).13
Normal and affected regions of interest were widely
clipped 15 mins prior to thermographic image acquisition. The region of interest in control cats corresponded
to a 100 cm2 area on the left side of the abdomen, just
caudal to the last rib. Cats were placed on a metal table
in a temperature-controlled (22°C) room with no air
drafts. Cats were not sedated or anesthetized, to prevent
potential interference of drugs with skin temperature.
Images were acquired using a FLIR T650sc camera (WiFi infrared camera; resolution 307,000 pixels, sensitivity
30 mK), positioned at a 50 cm distance from the skin surface and maintained at a 90° angle to the target. Images
were analyzed using software (FLIR Tools) and the following parameters measured: tumoral area (TA), the
circular area encompassing tumoral masses; and nontumoral area (nTA), the circular area of similar width
located at least 3 cm away from tumor borders.
Histologic and immunohistochemical analysis
Following surgical resection, tumor specimens were
immersed in 10% formaldehyde solution and processed
Journal of Feline Medicine and Surgery 23(6)
for histologic and immunohistochemical analysis. Tissue
sections (5 µm) were stained with hematoxylin and eosin
and analyzed under a Nikon microscope. Sarcomas were
graded according to cell differentiation, degree of necrosis and mitotic index.14
FISS subtypes were determined according to positivity of the following markers: smooth muscle alpha
(α)-actin, glial fibrillary acidic protein (GFAP), enolase, S-100, desmin, vimentin, CD204, PNL-2, CD31,
CD3 and CD20.15 Sarcoma tissue sections (5 µm) were
used to prepare silanized slides. These were deparaffinized, hydrated and submitted to antigenic unmasking
in proteinase K, citrate buffer (pH 6.0) or EDTA (pH
9.0). Slides were then submitted to endogenous peroxidase blocking in H2O2 solution at 37°C for 30 mins.
After washing in distilled water and wash buffer (trisbuffered saline + Tween 20 [TTBS]), protein was
blocked in skimmed milk solution for 30 mins at
37°C, washed in TTBS and submitted to Protein Block
(Novocastra Leica Biosystems) for 10 mins in an oven
at 25°C. Tumor sections were incubated overnight with
the following primary antibodies and dilutions: smooth
muscle α-actin (1:10000; Sigma), GFAP (1:500; Leica),
enolase (1:2000; Dako), S-100 (1:3000; Dako), desmin
(1:200; Dako), vimentin (1:5000; Dako), CD204 (1:1000;
CosmoBio), neuropeptide-like protein 2 (1:100; Santa
Cruz Biotechnology), CD31 (1:100; Dako), CD3 (1:1000;
Leica) and CD20 (1:100; Thermo Fisher). After incubation, slides were washed in TTBS and incubated with
post-primary reagent (Novocastra Leica Biosystems) for
30 mins at 20–25°C. The Novolink polymer Max Polymer
Detection System (Novocastra Leica Biosystems) was
then applied for 30 mins at 20–25°C. Next, slides were
washed in TTBS and revealed with tetrachloride of
3,3'-diaminobenzidine tetrahydrochloride chromogen
(Novocastra Leica Biosystems) for 5 mins at room temperature. After washing in distilled water, slides were
stained with Harris Hematoxylin (Merck), washed
again and rinsed in two baths of ammonia water (0.5%).
Finally, slides were dehydrated, diaphanized and
mounted using a coverslip. Reactions were validated
using positive control tissues for each antibody. For
negative control, the primary antibody was omitted
from the reaction and replaced by the diluent.
Statistical analysis
Quantitative data analysis was based on sample means
and SDs. Data normality was confirmed using the
Shapiro–Wilk test and intergroup comparisons performed
using the Student’s t-test. The level of significance was
set at 5% (P <0.05). The receiver operating characteristic
(ROC) curve was built using the bootstrap methodology
to assess the influence of tumor temperature to predict
tumor malignancy. The accuracy of each cut-off index in
predicting tumor malignancy was given by the area on
the ROC curve, which allowed the calculation of the most
Nitrini et al
515
accurate cut-off values using the highest Youden index.
Statistical tests were performed using software (RStudio,
Version 0.99.903).
Results
The tumor group comprised 31 neutered cats, 19 females
and 12 males. The cats’ ages ranged from 3 to 16 years
(mean 9.1 ± 3.9 years). Body weight ranged from 2.5 kg to
7.4 kg (mean weight 4.9 ± 1.3 kg). The sample comprised
one (3%) Ragdoll, 26 (84%) mixed breed and four (13%)
Siamese cats. Disease progression time ranged from 15
days to 3 years (mean 213 days). Tumors measured 0.6–
9.5 cm in length (craniocaudal axis; mean 4.3 ± 2.4 cm),
0.6–8.2 cm in width (dorsoventral axis: mean 3.8 ± 2.1 cm)
and 0.2–6 cm in depth (perpendicular axis; mean
2.2 ± 1.3 cm). Most tumors were located in the abdominal region (Table 1). The following tumors were represented: FISS (n = 21), apocrine cystadenoma (n = 3),
apocrine ductal adenoma (n = 2), follicular infundibular
cyst (n = 1), lipoma (n = 1), trichoblastoma (n = 1), apocrine ductal carcinoma (n = 1) and apocrine cystadenocarcinoma (n = 1). FISS histologic subtypes were as follows:
fibrosarcoma (n = 11), pleomorphic sarcoma (n = 7), histiocytic sarcoma (n = 2) and rhabdomyosarcoma (n = 1).
Most sarcomas in this sample were grade 2, followed by
grade 3 and grade 1 (n = 12, n = 7 and n = 2, respectively).
Seven of 31 cats (23%, all in the FISS group) had been submitted to previous tumor resection and presented with
recurring tumors within 6 months, on average.
Overall, temperatures recorded in TA and nTA areas
ranged from 32.6°C to 38.4°C (mean 35.1 ± 1.9°C) and
31.9°C to 37.8°C (mean 34.9 ± 1.5°C), respectively, with
no significant differences (P = 0.32) between TA and nTA.
Temperature differences were positive (ie, TA warmer
than nTA) in 13 and negative (ie, TA colder than nTA) in
16 cases (42% and 51%, respectively). Two cats had similar TA and nTA temperatures.
The control group comprised 11 neutered, mixed breed
cats (seven males and four females). The control cats were
aged 3–16 years (mean age 8 ± 5 years) and weighed 3.4–
6.8 kg (mean body weight 5 ± 2 kg). Mean normal skin
temperature ranged from 32.9°C to 36.9°C (mean temperature 35 ± 1.4°C) and did not differ significantly from
mean temperatures recorded in cats in the tumor group
(nTA and TA, P = 0.85 and P = 0.84, respectively).
Thermographic images revealed higher temperatures
in malignant tumors (FISS, carcinomas and adenocarcinomas) than in benign tumors (35.4 ± 1.8°C and 34.5 ± 1.7°C,
respectively; P = 0.01) (Figures 1 and 2). The cut-off point
analysis showed that TA >34.7°C constitutes a crucial
point that discriminates with accuracy (sensitivity 76%,
specificity 80%, area under the ROC curve 0.761; P = 0.01)
a malignant from a benign tumor. With regard to malignant tumors, significantly higher temperatures were
detected in FISS compared with carcinomas and adenocarcinomas (35.6 ± 1.7°C and 33.4 ± 1.4°C, respectively;
P = 0.04). Temperature differences between TA and nTA
were also compared in order to avoid potential biases
Table 1 Characteristics of cats presenting with skin and soft tissue tumors according to tumor malignancy
Malignant
Sex
Male
Female
Mean ± SD age (years)
Mean ± SD weight (kg)
Breed
Mixed breed
Siamese
Ragdoll
Mean ± SD tumor size (cm)
Length
Width
Depth
Location
Cervical
Chest
Abdomen
Limb
Mean ± SD disease progression
(days)
Benign
n
(%)
n
6
17
9.1 ± 3.8
4.7 ± 1.3
26
74
6
2
9.3 ± 4.4
5.6 ± 1.3
18
4
1
78
17
4
8
–
–
4.8 ± 2.4
4.1 ± 2.2
2.3 ± 1.3
1
2
20
–
201 ± 247
Total
(%)
75
25
100
3.0 ± 1.8
3.0 ± 1.6
1.8 ± 1.1
4
9
87
–
1
–
6
1
249 ± 345
n
(%)
12
19
9.1 ± 3.9
4.9 ± 1.3
39
61
26
4
1
84
13
3
4.3 ± 2.4
3.8 ± 2.1
2.2 ± 1.3
12
–
76
12
2
2
26
1
213 ± 270
6
6
84
3
Journal of Feline Medicine and Surgery 23(6)
516
Figure 1 Temperature readings in benign and malignant
tumors (P = 0.01)
introduced by individual body temperature. However,
significant differences between malignant and benign
tumors persisted (P = 0.01).
FISSs in this sample were either warmer (12 tumors,
57%) or colder (eight tumors, 38%) than surrounding
tissues. Mean temperature differences corresponded
to 1.4°C and 0.7°C (warmer and colder tumors, respectively). In one case, temperatures detected in TA and
nTA did not differ. Temperatures detected in FISS did
not differ significantly according to histologic subtype
(P = 0.91) or tumor grade (P = 0.46). However, grade 1
sarcomas tended to be colder than higher grade sarcomas.
Temperature readings in primary and recurring tumors
were also similar (P = 0.25).
Temperature readings according to histologic diagnosis and FISS subtype and grade are shown in Table 2.
Figure 2 Thermographic images: (a) trichoblastoma affecting the right forelimb (tumoral area [TA] 33.7ºC); (b) feline injection
site sarcoma (pleomorphic sarcoma) affecting the lateral abdominal wall (TA 35.6ºC)
Table 2 Mean temperature readings (ºC) in tumoral areas (TAs) and non-tumoral areas (nTAs) of feline skin and soft
tissue tumors according to tumor type, histologic subtype and grade
Tumor type
Apocrine cystadenoma
Apocrine ductal adenoma
Lipoma
Trichoblastoma
Follicular infundibular cyst
Apocrine ductal carcinoma
Apocrine cystadenocarcinoma
FISS
Fibrosarcoma
Pleomorphic sarcoma
Histiocytic sarcoma
Rhabdomyosarcoma
Grade I
Grade II
Grade III
n
TA
nTA
P value
3
2
1
1
1
1
1
34.9 ± 0.9
35.1 ± 1.6
31.8
33.7
31.6
32.4
34.4
34.7 ± 1.4
35.3 ± 1.4
33.4
34.2
31.9
34.4
35.2
0.01*
11
7
2
1
2
12
7
35.8 ± 1.7
35.2 ± 2
36 ± 1.5
36.4
34 ± 1.9
35.9 ± 1.8
35.7 ± 1.4
35.3 ± 1.3
34.8 ± 1.9
36.4 ± 2.1
33.3
33.1 ± 1.2
35.1 ± 1.4
35.7 ± 1.5
0.91†
Data are n (number of cats) or mean ± SD
*Significant difference between temperature readings in benign and malignant tumors
†Lack of significant differences between feline injection site sarcoma (FISS) histologic subtypes
‡Lack of significant differences between FISS grades
0.46‡
Nitrini et al
Discussion
The findings of this study supported the applicability
of thermography for thermal characterization of normal skin and skin overlying neoplastic lesions in cats.
Inflammatory cytokines associated with neoplastic
lesions are thought to induce thermal changes in peritumoral areas. In this study, mean temperatures recorded
in areas of normal skin (control cats) were used for comparative purposes. The flank region was selected owing
to the high FISS incidence rates on the lateral aspect of
the abdominal wall. Contralateral symmetry has been
reported in human and canine thermographic imaging
studies.3,16 Therefore, only the left side of the abdomen
was scanned in this study. In spite of wide variation
between cats, mean temperatures recorded in control cats
and nTA in cats in the tumor group were similar.
Although mean temperatures detected in TA and nTA
in this study did not differ significantly, the technique
allowed fast, safe and effective detection of temperature
differences between TA and nTA in most cases. Such differences may assist in tumor location and margin demarcation. Similar findings have been reported in medical
oncology, where thermography is routinely used. A 2015
study involving 60 women with suspected neoplastic
mammary disease and comparing thermographic and
ultrasonographic image findings with biopsy results
reported up to 75% sensitivity of thermography for accurate lesion location and 100% sensitivity when asymmetry between left and right mammary gland images were
accounted for.10
Studies describing thermographic assessment of neoplasms are scarce in veterinary medicine. Redaelli et al6
investigated 110 animals affected with a wide range of neoplastic conditions, including six cats with cutaneous fibrosarcoma. Thermography failed to facilitate lesion location
in that study; however, the interference of long, thick hair
with proper image acquisition was emphasized. Cats in this
sample were therefore submitted to hair clipping. Clipping
was thought to contribute to tumor margin demarcation
and accurate temperature measurement in target areas.
Ambient temperature control and lack of air drafts or sunlight during image acquisition were also thought to be
critical for thermographic assessment. Studies in horses
revealed positive correlations between increased joint and
ambient temperature, emphasizing the need for examination in a temperature-controlled environment.2,17
In this study, the analysis showed that a TA temperature above 34.7°C is significantly associated with the presence of malignancy, making thermography an auxiliary
method in determining the prognosis. In humans, thermography is also used to facilitate tumor location and to
distinguish between benign and malignant neoplasms, as
malignant tumors tend to be warmer than benign lesions.
Examples of this type of distinction include basal cell
carcinoma, actinic dermatitis, melanoma and pigmented
seborrheic keratosis.18,19 Higher temperatures detected
517
in FISS than in other tumors in this sample, including
carcinomas, suggest sarcomas are more vascularized
and have higher metabolic activity. Higher temperatures
(up to 5°C) in a FISS vs surrounding tissues have been
reported elsewhere.20,21
Temperatures detected in TA and nTA did not differ
significantly in the FISSs in this sample. Still, thermographic patterns varied widely between these tumors.
Similar to canine mast cell tumors,22 FISSs were warmer
than surrounding tissues in approximately half of cases.
Varying degrees of intratumoral necrosis and peritumoral
inflammation may explain these differences. Temperature
variations between benign tumors were also noted, with
one adenoma showing a similar temperature to FISS. This
may have reflected large tumor size, as the adenoma in
question was one of the largest tumors in this sample
(5.6 cm in width). Inclusion of tumors of different size
and disease progression time may have contributed to
temperature disparities in this study and may have been
a limiting factor in this analysis.
With regard to FISS histologic subtypes, higher (albeit
not significantly different) average temperatures were
recorded in histiocytic sarcomas and rhabdomyosarcomas than in fibrosarcomas and pleomorphic sarcomas. Likewise, grade I tumors tended to be colder than
higher grade tumors, suggesting a positive relationship
between tumor temperature and malignancy. Studies
with larger samples may yield more consistent results
regarding the value of thermography in FISS subtype
determination and grading, in addition to finding a cutoff value to differentiate FISS from other skin and soft
tissue malignancies.
Temperature changes, even in small tumors (<1 cm
in width), was an interesting finding in this study and
emphasized the high sensitivity of thermographic cameras. Different from ancillary modalities such as radiography, in which lesion size is a significant diagnostic factor,
thermal imaging allows early detection of tumoral activity (ie, from the moment blood flow increases to support
tumor growth).23
This study has some limitations, such as the small
number of cats in the control group and a heterogeneous
sample in the tumor group. Also, the number of malignant
tumors other than FISSs was too small for comparison of
temperature differences. Limitations inherent to the technique must also be emphasized. Thermographic assessment can be used to detect temperature gradients, but not
to distinguish between inflammatory, infectious and neoplastic processes. Therefore, in spite of high sensitivity, the
method has low specificity. Shallow measurement depth
(a few centimeters below the skin surface) is another limitation of thermography.4,6 Also, given the potential effects
of sedation and/or anesthesia on image acquisition, thermographic assessment is limited to docile animals amenable to physical restraint and hair clipping. Finally, the high
cost of thermographic cameras must be accounted for.
Journal of Feline Medicine and Surgery 23(6)
518
More affordable, recently developed models may increase
access to thermography in the near future.
Conclusions
Thermography proved to be a good method for skin and
soft tissue tumor assessment in cats. Effective detection of
temperature differences between malignant and benign
tumors with a similar clinical presentation is a major
benefit of thermographic assessment. Studies with larger
samples and investigating other types of skin and soft
tissue tumors are warranted for technical refinement and
more comprehensive assessment of the value of thermography in diagnosis, prognostic estimation and follow-up
of neoplastic diseases in cats.
Author note The preliminary results of this study were part
of a poster presentation at the European Society of Veterinary
Oncology Congress, Hofhein, Germany, in May 2019.
Conflict of interest The authors declared no potential
conflicts of interest with respect to the research, authorship,
and/or publication of this article.
Funding This study was partially funded by Coordenação
de Aperfeiçoamento de Pessoal de Nível Superior – Brasil
(CAPES) – Finance Code 001.
Ethical approval This work involved the use of nonexperimental animals only (including owned or unowned
animals and data from prospective or retrospective studies).
Established internationally recognised high standards (‘best
practice’) of individual veterinary clinical patient care were
followed. Ethical approval from a committee, while not necessarily required, was nonetheless obtained, as stated in the
manuscript.
Informed consent Informed consent (either verbal or
written) was obtained from the owner or legal custodian of
all animal(s) described in this work (either experimental or
non-experimental animals) for the procedure(s) undertaken
(either prospective or retrospective studies). For any animals
or humans individually identifiable within this publication,
informed consent (either verbal or written) for their use in the
publication was obtained from the people involved.
ORCID iD Andressa Gianotti Campos Nitrini
https://
orcid.org/0000-0002-5589-8052
Julia Maria Matera
https://orcid.org/0000-0001-8349-1340
References
1 Tepper M and Gannot I. Monitoring tumor state from thermal images in animal and human models. Med Phys 2015;
42: 1297–1306.
2 Brioschi Ml, Macedo JF and Macedo RAC. Termometria
cutânea: novos conceitos. J Vasc Bras 2003; 2: 151–160.
3 Loughin CA and Marino DJ. Evaluation of thermographic
imaging of the limbs of healthy dogs. Am J Vet Res 2007;
68: 1064–1069.
4 Arora N, Martins D, Ruggerio D, et al. Effectiveness of a
noninvasive digital infrared thermal imaging system in
the detection of breast cancer. Am J Surg 2008; 196: 523–526.
5 Vainionpää MH, Raekallio MR, Junnila JJ, et al. A comparison of thermographic imaging, physical examination and
modified questionnaire as an instrument to assess painful conditions in cats. J Feline Med Surg 2013; 15: 124–131.
6 Redaelli V, Tanzi B, Luzi F, et al. Use of thermographic
imaging in clinical diagnosis of small animal: preliminary notes. Ann Ist Super Sanita 2014; 50: 140–146.
7 Pouzot-Nevoret C, Barthélemy A, Goy-Thollot I, et al.
Infrared thermography: a rapid and accurate technique to
detect feline aortic thromboembolism. J Feline Med Surg
2018; 20: 780–785.
8 Mikulska D. Contemporary applications of infrared imaging
in medical diagnostics. Ann Acad Med Stetin 2006; 52: 35–39.
9 Herman C and Cetingul MP. Quantitative visualization
and detection of skin cancer using dynamic thermal imaging. J Vis Exp 2011; 5: 2679. DOI: 10.3791/2679.
10 Zadeh H, Haddadnia J, Ahmadinejad N, et al. Assessing
the potential of thermal imaging in recognition of breast
cancer. Asian Pac J Cancer Prev 2015; 16: 8619–8623.
11 Pavelski M, Silva DM, Leite NC, et al. Infrared thermography in dogs with mammary tumors and healthy dogs.
J Vet Intern Med 2015; 29: 1578–1583.
12 Bowlt K. Feline injection site-associated sarcomas. In Pract
2015; 37: 2–8.
13 Levy JK, Nutt KR and Tucker SJ. Reference interval for rectal temperature in healthy confined adult cats. J Feline Med
Surg 2015; 17: 950–952.
14 Couto SS, Griffey SM, Duarte PC, et al. Feline vaccineassociated fibrosarcoma: morphologic distinctions. Vet
Pathol 2002; 39: 33–41.
15 Ramos-Vara JA and Borst LB. Immunohistochemistry:
fundamentals and applications in oncology. In: Meuten
DJ (ed). Tumors in domestic animals. 5th ed. Chichester:
Wiley-Blackwell, 2016, pp 44–87.
16 Herry CL and Frize M. Quantitative assessment of painrelated thermal dysfunction through clinical digital infrared thermal imaging. Biomed Eng Online 2004; 3: 19. DOI:
10.1186/1475-925X-3-19.
17 Machado LFS, Dittrich Rl, Pavelski M, et al. Padronização
do exame termográfico nas articulações do carpo e metacarpofalangeanas de cavalos em treinamento. Arch Vet Sci
2013; 18: 40–45.
18 Stringasci MD, Moriyama LT, Salvio AG, et al. Thermographic diagnostics to discriminate skin lesions: a clinical
study. Biophotonics South America Proceedings, International Society for Optical Engineering; 2015 May 23–25;
Bellingham, WA, USA.
19 Magalhaes C, Vardasca R and Mendes J. Recent use of
medical infrared thermography in skin neoplasms. Skin
Res Technol 2018; 24: 587–591.
20 Mocanu J, Militaru M, Ciobotaru E, et al. Thermography
aspects of feline fibrosarcoma complex. Vet Dermatol 2004;
15: 62. DOI: 10.1111/j.1365-3164.2004.00414_66a.x.
21 Sanz Tolón A, Vicente Rubiano M, Barneto Carmona A,
et al. Diagnóstico de fibrosarcoma felino por imagen
termográfica. RCCV 2008; 2: 134–140.
22 Melo SR, Macedo TR, Cogliati B, et al. Thermographic
assessment of canine mast cell tumours. Indian J Appl Res
2015; 5: 47–51.
23 Milosevic M, Jankovic D and Peulic A. Comparative analysis of breast cancer detection in mammograms and thermograms. Biomed Tech (Berl) 2015; 60: 49–56.