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Biomechanical and microbiological analysis of embalmed cats – acute effect of conservation

Abstract

Animals corpses in teaching and research institutions could be sources of infection for students and teachers when applied for dissection and surgical practice. This research aimed to evaluate cats’ corpses’ conservation using a new anatomic technique and vacuum package for seven days, aiming surgical practicing. A 150 mL/kg of alcohol with 5% glycerin and 120 mL/kg of a 20% sodium chloride, 1% nitrite, and 1% sodium nitrate solution was injected on corpses sealed in vacuum packages and put on 0 to 4°C. Skin and jejunum were collected on day 0 (fresh samples/control), and traction analysis was performed for seven consecutive days. On the last day, the liquid in the plastic bags was microbiologically analyzed. There was no statistical difference between control and conservation moments (D1 and D2) in maximal rupture force of the skin, and jejunum was similar to control in D2, D4, and D6. The microbial population did not exceed 6.0x104CFU/mL in total aerobics and 4.8x104CFU/mL in total anaerobes. Biomechanics was not significantly affected, and the microbiological count was low during conservation, demonstrating the possible effectiveness of this anatomical technique for surgery training.

Key words
anatomy; microorganisms; acute effect; curing salt; surgery

INTRODUCTION

Embalming is a process using chemical solutions to sanitize and preserves corpses after death. For more than 5,000 years, there has been a concern for preserving anatomical specimens, and human beings have tried to stop after-death body decay (Cury et al. 2013CURY FS, CENSONI JB & AMBRÓSIO CE. 2013. Técnicas anatômicas no ensino da prática de anatomia animal. Pesq Vet Bras 33: 688-696., Balta et al. 2015BALTA JY, CRONIN M, CRYAN JF & O ́MAHONY SM. 2015. Human Preservation Techniques in Anatomy: A 21st Century Medical Education Perspective. Clin Anat 28: 725-734.). Fresh corpses present limited handling time due to rapid putrefaction and risk of infection (Hayashi et al. 2014HAYASHI S ET AL. 2014. Saturated Salt Solution Method: A Useful Cadaver Embalming for Surgical Skills Training. Med J 93: 1-10.). It is necessary to use fixation and preservation methods to keep tissues firm, insoluble, and protected (Calamares Neto & Colombo 2015CALAMARES NETO JE & COLOMBO TE. 2015. Isolamento e identificação de fungos filamentosos em peças anatômicas conservadas em formol. J Health Sci Inst 33: 218-222.).

Embalming solutions can eliminate bacteria such as Proteus vulgaris, Pseudomonas aeruginosa, and Staphylococcus aureus. Animals and human corpses, used in teaching and research institutions, could be a source of infection for both students and teachers when used for surgical practicing and dissection. Therefore, embalming is used to reduce or eliminate the risks of zoonoses transmission, ethical considerations, teaching effectiveness, hygiene of the professional environment, economic pressures, and adverse publicity. For this reason, legal rules were established for the use of these animals in research and classes, thus ensuring their welfare (Arluke 2004ARLUKE A. 2004. The use of dogs in medical and veterinary training: understanding and approaching Student uneasiness. J Appl Anim Welf Sci 7: 197-204., Balta et al. 2015BALTA JY, CRONIN M, CRYAN JF & O ́MAHONY SM. 2015. Human Preservation Techniques in Anatomy: A 21st Century Medical Education Perspective. Clin Anat 28: 725-734.).

An embalmed cadaver should present the same feature as a fresh corpse. Several fixatives and preservatives solutions can be used in corpses to prevent decay. Studies reported that embalmed bodies changed the tissue and joints quality, which stayed rigid, decrease the range of motion (Balta et al. 2015BALTA JY, CRONIN M, CRYAN JF & O ́MAHONY SM. 2015. Human Preservation Techniques in Anatomy: A 21st Century Medical Education Perspective. Clin Anat 28: 725-734., Hayashi et al. 2016HAYASHI S, NAITO M, KAWATA S, QU N, HATAYAMA N, HIRAI S & ITOH M. 2016. History and future of human cadaver preservation for surgical training: from formalin to saturated salt solution method. Anat Sci Int 91: 1-7.). The most used fixatives are glycerin, ethyl alcohol, phenol, and formaldehyde (Rodrigues 2010RODRIGUES H. 2010. Técnicas anatômicas. GM Gráfica & Editora. Vitória-ES, 269 p., Balta et al. 2015BALTA JY, CRONIN M, CRYAN JF & O ́MAHONY SM. 2015. Human Preservation Techniques in Anatomy: A 21st Century Medical Education Perspective. Clin Anat 28: 725-734., Hammer et al. 2014HAMMER N, LÖFFLER S, BECHMANN I, STEINKE H, HÄDRICH C & FEJA C. 2014. Comparison of modified thiel embalming and ethanol-glycerin fixation in an anatomy environment: Potentials and limitations of two complementary techniques. Anat Sci Educ 8: 74-85., Hayashi et al. 2016HAYASHI S, NAITO M, KAWATA S, QU N, HATAYAMA N, HIRAI S & ITOH M. 2016. History and future of human cadaver preservation for surgical training: from formalin to saturated salt solution method. Anat Sci Int 91: 1-7.). At high levels, the latter causes tissue hardening (Hart 1990HART J. 1990. Cadaver preservation and dissection. Eur J Plast Surg 13: 75-78.) and affects the cadaver quality, mainly in soft tissues (Hayashi et al. 2014HAYASHI S ET AL. 2014. Saturated Salt Solution Method: A Useful Cadaver Embalming for Surgical Skills Training. Med J 93: 1-10.).

Thiel’s solution provides texture and color close to that of live animals and presents many applications in surgery, ultrasound, regional anesthesia, and airways anesthesiology research (Eisma et al. 2011EISMA R, MAHENDRAN S, MAJUMDAR S, SMITH D & SOAMES RW. 2011. A comparison of Thiel and formalin embalmed cadavers for thyroid surgery training. Surgeon 9: 142-146., 2013EISMA R, LAMB C & SOAMES RW. 2013. From formalin to Thiel embalming: what changes? One anatomy department’s experiences. Clin Anat 26: 564-571.). This solution contains salts, such as ammonium nitrate, potassium nitrate, and sodium sulfite, with small percentages of formaldehyde, ethylene glycol, boric acid, and p-chlorocresol (Rodrigues 2010RODRIGUES H. 2010. Técnicas anatômicas. GM Gráfica & Editora. Vitória-ES, 269 p., Hayashi et al. 2016HAYASHI S, NAITO M, KAWATA S, QU N, HATAYAMA N, HIRAI S & ITOH M. 2016. History and future of human cadaver preservation for surgical training: from formalin to saturated salt solution method. Anat Sci Int 91: 1-7.). The intense color obtained with this solution is due to nitrites and myoglobin in muscles that form nitrosomyoglobin (Hammer et al. 2014HAMMER N, LÖFFLER S, BECHMANN I, STEINKE H, HÄDRICH C & FEJA C. 2014. Comparison of modified thiel embalming and ethanol-glycerin fixation in an anatomy environment: Potentials and limitations of two complementary techniques. Anat Sci Educ 8: 74-85.). Food additives such as nitrite, nitrate, sodium chloride, and sugars are applied to keep the red color of cured meat and cause a bacteriostatic effect, maintaining its physical-chemical properties (Iamarino et al. 2015IAMARINO LZ, OLIVEIRA MC, ANTUNES MM, OLIVEIRA M, RODRIGUES RO, ZANIN CICB, SCHIMILE M & LIMA AA. 2015. Nitritos e Nitratos em produtos cárneos enlatados e/ou embutidos. Gestão em Foco 7: 246-251.).

Some embalming solutions have been tested with success. The ICL-SP (Imperial College London Soft-Preservation) solution with phenol, alcohol, water, and glycerol (Barton et al. 2009BARTON DPJ, DAVIES DC, MAHADEVAN V, DENNIS L, ADIB T, MUDAN S, SOHAIB A & ELLIS H. 2009. Dissection of soft-preserved cadavers in the training of gynaecological oncologists: Report of the first UK workshop. Gynecol Oncol 113: 352-356.) did not affect the joint flexibility, probably due to the presence of alcohol and absence of formaldehyde. Ethanol-glycerin-fixed specimens can keep the colorfastness, rigidity and joint motion better than formaldehyde-fixed tissues (Hammer et al. 2011HAMMER N, LÖFFLER S, FEJA C, BECHMANN I & STEINKE H. 2011. Substitution of formaldehyde in cross anatomy is possible. J Natl Cancer Inst 103: 610-611., 2012HAMMER N, LÖFFLER S, FEJA C, SANDROCK M, SCHMIDT W, BECHMANN I & STEINKE H. 2012. Ethanol-glycerin fixation with thymol conservation: A potential alternative to formaldehyde and phenol embalming. Anat Sci Educ 5: 225-233.), besides more pleasant odor (Hammer et al. 2014HAMMER N, LÖFFLER S, BECHMANN I, STEINKE H, HÄDRICH C & FEJA C. 2014. Comparison of modified thiel embalming and ethanol-glycerin fixation in an anatomy environment: Potentials and limitations of two complementary techniques. Anat Sci Educ 8: 74-85.).

Saturated salt solutions have proven to be effective in conservation, with low cost and contributing to the extensive use of embalmed corpses in surgical training (Hayashi et al. 2014HAYASHI S ET AL. 2014. Saturated Salt Solution Method: A Useful Cadaver Embalming for Surgical Skills Training. Med J 93: 1-10., 2016).

There is no ideal solution to embalm and preserve corpses. The solution should protect the cadavers from microorganisms that accelerate decomposition and make them bacteria-free (Balta et al. 2015BALTA JY, CRONIN M, CRYAN JF & O ́MAHONY SM. 2015. Human Preservation Techniques in Anatomy: A 21st Century Medical Education Perspective. Clin Anat 28: 725-734.). The use of corpses has been described as the best method for training medical specialties, promoting great learning, increasing efficiency and confidence, decreasing costs, and allowing repetition (Balta et al. 2018BALTA JY, TWOMEY M, MOLONEY F, DUGGAN O, MURPHY KP, O’CONNOR OJ, CRONIN M, CRYAN JF, MAHER MM & O’MAHONY SM. 2018. A comparison of embalming fluids on the structures and properties of tissue in human cadavers. Anat Histol Embryol 47: 1-10., Rocha et al. 2019ROCHA TASS, SANTOS CCC, IOZZI MT, DIAS RS, ZERO RC, CARDOZO MV & OLIVEIRA FS. 2019. Chemically prepared dog cadavers in the teaching of surgical technique - evaluation by students of a veterinary medicine course. Acta Sci Anat 1: 136-140.).

This paper aimed to evaluate the conservation of vacuum-packed cat corpses fixed with glycerinated ethyl alcohol and curing salt for veterinary surgical practicing throughout seven days by measuring the maximum rupture force (in Newtons - N) and the rupture elongation (mm) of the skin and jejunum, besides microbiological analysis during the conservation.

MATERIALS AND METHODS

Eight cat corpses, males and females, adults, weighing 3.76±1.27kg, and whose death did not involve morphological changes were used. Cadavers were obtained from the Zoonosis Control Center in Ribeirão Preto, SP, and the donation was approved by the Municipal Legal Department (process 02.2014.000027-1) and by the local ethics committee of UNESP - Jaboticabal (process 4593/19). The animals were frozen (freezer at -18°C) after death and then transported to the Laboratory of Animal Anatomy at UNESP Jaboticabal, SP, located 50km away.

The animals’ body score was 5 (palpable ribs without excessive adipose coverage, when viewed from above; the waist is seen behind the ribs, and the abdomen can be seen retracted from the side), on a scale of 1 to 9, considered as an ideal score body for cats by Laflamme (1997)LAFLAMME D. 1997. Development and validation of a body condition score system for cats: a clinical tool. Feline Pract 25: 13-18..

Anatomical technique

Corpses were thawed in tapping water for 12h, and trichotomy was performed, focusing on not causing any damage to the skin. Three skin and jejunum fragments were collected (fresh/control, before fixation). For skin collecting, corpses were initially positioned in the right lateral decubitus. With a scalpel (blade number 23), a 1x5cm stainless steel mold was contoured in three sequential skin samples, perpendicular to the tension lines of the cat’s skin, on the lateral of the thorax, and 5cm away from the median plane (Figure 1), which is the direction that provides higher tensile strength (Haar et al. 2013HAAR G, BUIKS SC, VAN DELDEN M, REIJNTJES T, SANCHEZ RF & KIRPENSTEIJN J. 2013. Skin tension. In: Kirpensteijn J & Haar G. (Eds) Reconstrutive surgery and wound management of the dog and the cat. London, p. 12-14.), as demonstrated in the sheep (Jacinto et al. 2004JACINTO MAC, SILVA SOBRINHO AG & COSTA RG. 2004. Características anátomo-estruturais da pele de ovinos (Ovis áries) lanados e deslanados, relacionadas com o aspecto físico-mecânico do couro. R Bras Zootec 33: 1001-1008.). A median celiotomy was performed for the jejunum collecting, the intestine exteriorized, and the duodenojejunal flexure identified; the steel mold was positioned to delimit the sample, which was then sectioned longitudinally with a Metzenbaum scissor. Subsequently, a section of the mesenteric border was performed, exposing the lumen for the incision using the same stainless steel mold (three 1x5cm fragments from each animal) (Figure 2). Then, samples were immediately subjected to biomechanical analysis. After collecting the samples (D0-Fresh sample/control group), the common carotid artery was dissected, a 40x12 cannula was inserted on it, and 150ml/kg of ethyl alcohol (Usina São Martinho®, Pradópolis, SP) with 5% glycerin (Dinâmica®, Indaiatuba, SP) (EA) and 120ml/kg of curing salt solution (CSS) were injected. The CSS was prepared with 200g/L of sodium chloride (Cisne®, Cabo Frio, RJ), 10g/L of sodium nitrite (Êxodo Científica®, Sumaré, SP), and 10g/L of sodium nitrate (Êxodo Científica®, Sumaré, SP). Then, the corpses were individually vacuum-packed (Figure 3) by a professional machine (Cetro® DZ Q600 DE) and kept in a horizontal refrigerator (Fricon®, Paulista, PE) between 0 and 4°C.

Figure 1
Cat positioned in right lateral decubitus to collect three samples of the skin parallel and 5cm from the median line on the chest.
Figure 2
Jejunum sample collected in the longitudinal direction in an embalmed cats’ corpse.
Figure 3
A vacuum-packed cat after fixation with ethyl alcohol and curing salt.

Tissues samples were taken daily for seven days. The packages were opened every day, collected, and put the animals in another sterile plastic bag so the vacuum could be done again.

Biomechanical analysis

To assess tissue resistance, an EMIC® Universal Testing Machine - model DL-2000 was used. A 500N load cell, a 100mm/min displacement speed, and a 20mm gap space between the grips were applied. The equipment belongs to the Laboratory of Surgical Anatomy of the Department of Animal Morphology and Physiology at São Paulo State University in Jaboticabal.

A traction test was conducted up to the point of rupture of the skin and jejunum.

Microbiological analysis

Microbiological analyses were performed on the last day of conservation (D7) in 3 corpses/packages, randomly chosen. As a large amount of solutions was injected, extrapolating the blood volume of the animal, there was always some liquid on the plastic bag. For each analysis, 10mL were collected in previously sterilized bottles and sent to the Microbiology Laboratory of the Institution.

The surface plating technique was used to quantify viable facultative aerobic and anaerobic bacteria. In this technique, samples are diluted five times, 100µl as an inoculum, and distributed on agar surface plates, spreading with the Drigalski loop. The plates for counting aerobic microorganisms were stored directly in a bacteriological incubator. While the plates for counting anaerobic microorganisms were stored in anaerobic jars using Anaeroback (Probac), both incubated at 37°C for 24h. After this period, the colony-forming unit (CFU) was counted per mL using a magnifying glass (Vanderzant & Splittstoesser 1992VANDERZANT C & SPLITTSTOESSER DE. 1992. Compendium of methods for the microbiological examination of foods. 3rd ed. Washington, American Public Health Association, 1219 p., Jay 2005JAY JM. 2005. Microbiologia de alimentos. 6a ed. Porto Alegre, Artmed.). Five colonies isolated from each plate on BHI agar (brain heart infusion), with different phenotypic characteristics, incubated at 37°C for 24 hours for later identification of the genera Streptococcus sp., Bacillus sp, Pseudomonas sp., Escherichia coli species, and Clostridium sp. Selective culture media sown for the genera analyzes SPS agar (sulfite-polymyxin-sulfadiazine) to identify the genus Clostridium, Mac Conkey agar, to evaluate Pseudomonas and Escherichia coli; and MYP base agar (mannitol-yolk-polymyxin) for isolation of Bacillus. Cultures were assessed for cell morphology, presence of spores, Gram classification after 24 hours of incubation at 37°C (Barrow & Feltham 1993BARROW GI & FELTHAM RKA. 1993. Cowan and Steel ́s. Manual for the identification of medical bacteria. 3rd ed. Cambridge, Cambridge University, 331 p.).

RESULTS

All analyses were performed using the R 3.6.1 software for Windows. Box cox transformation of the data to guarantee homoscedasticity, when necessary. Cramer-Von Mises normality test (p=0.1894) of the residues were taken, Analysis of Variance (ANOVA) (5% and 1%) were performed, and then the Tukey test (5%).

The mean and standard deviation of the MRF and RE for skin and jejunum rupture are shown in Tables I and II.

Table I
Mean and standard deviation of the maximum rupture force (MRF) and rupture elongation (RE) of the skin samples from cat cadavers chemically prepared and vacuum packaging for up to 7 days.
Table II
Mean and standard deviation of the maximum rupture force (MRF) and rupture elongation (RE) of the jejunum samples from cat cadavers chemically prepared and vacuum packaging for up to 7 days.

In MRF data, the outliers were removed, and data subjected to box cox transformation (λ=0.6) using the Cramer-Von Mises test and p=0.5421. According to ANOVA (p=0.06), there is no significant difference between times (Table III).

Table III
Analysis of variance of the MRF of the jejunum of cadavers of cats chemically preserved under the acute effect of conservation for seven days.

In RE data, outliers were removed, and data submitted to box cox transformation (λ=0.25) with Cramer-Von Mises test (p=0.4593). According to ANOVA, there was no significant difference between different times (Table IV).

Table IV
Analysis of variance of the RE of the jejunum of cadavers of cats chemically preserved under the acute effect of conservation for seven days.

In the Tukey test of skin MRF, the moments D1 and D2 were similar to the control group; the same occurred for RE (Table I). The jejunum MRF was similar to the control group on D2, D4, and D6. At the same time, the RE was similar in moments D2 and D6 (Table II).

Microbiological analysis was performed on three of the eight vacuum corpses packs (Table V).

Table V
Microbiological analysis of the liquid contained in the vacuum packaging from three randomly chosen cadavers.

DISCUSSION

Anatomical technique

The use of EA as a fixative agent proved to be efficient for cats’ corpses, demonstrating adequate conservation and avoiding deterioration, similarly to the reported in dogs’ (Rocha et al. 2018ROCHA TASS, YANAGIHARA GR, SHIMANO AC, ROLIM GS, SANTOS CCC, FECHIS ADS & OLIVEIRA FS. 2018. Biomechanical analysis of the skin and jejunum of dog cadavers subjected to a new anatomical preservation technique for surgical teaching. J Plast 30: 16-23.) and cat (Fração et al. 2019FRAÇÃO VC, ZERO RC, RODRIGUES A, FERREIRA BN, FECHIS ADS, ROCHA TASS, IOZZI MT & OLIVEIRA FS. 2019. Analysis of the Skin of Cats’ Corpses Chemically Prepared with Ethylic Alcohol and Curing Salt Aiming Veterinary Surgical Practice - Chronic Effect on Biomechanics and Students’ Evaluation. CPQ Med 4: 1-8.) cadavers in surgery training. Also, alcohols used as a fixative in human cadavers from 6 months to 1 year kept tissue quality similar to fresh tissue (Goyri-O’Neill et al. 2013GOYRI-O’NEILL J, PAIS D, FREIRE DE ANDRADE F, RIBEIRO P, BELO A, O’NEILL A, RAMOS S & NEVES MARQUES C. 2013. Improvement of the embalming perfusion method: The innovation and the results by light and scanning electron microscopy. Acta Med Port 26: 188-194.). The solution maintained the color, rigidity, and joint motion better than formaldehyde-fixed tissues (Hammer et al. 2011HAMMER N, LÖFFLER S, FEJA C, BECHMANN I & STEINKE H. 2011. Substitution of formaldehyde in cross anatomy is possible. J Natl Cancer Inst 103: 610-611., 2012).

The use of 30% sodium chloride aqueous solution (30% SCAS) was evaluated in a 5-year study and proved efficient in conserving fixed tissues, with no visual contamination, unwanted odors, and loss of softness and color (Oliveira 2014OLIVEIRA FS. 2014. Assessing the effectiveness of 30% sodium chloride aqueous solution for the preservation of fixed anatomical specimens: a 5-year follow-up study. J Anat 225: 118-121.). This solution proved to be effective in the conservation of dogs previously fixed with EA for up to 120 days (Rocha et al. 2018ROCHA TASS, YANAGIHARA GR, SHIMANO AC, ROLIM GS, SANTOS CCC, FECHIS ADS & OLIVEIRA FS. 2018. Biomechanical analysis of the skin and jejunum of dog cadavers subjected to a new anatomical preservation technique for surgical teaching. J Plast 30: 16-23.) and in cats fixed with EA and CSS for up to 90 days (Fração et al. 2019FRAÇÃO VC, ZERO RC, RODRIGUES A, FERREIRA BN, FECHIS ADS, ROCHA TASS, IOZZI MT & OLIVEIRA FS. 2019. Analysis of the Skin of Cats’ Corpses Chemically Prepared with Ethylic Alcohol and Curing Salt Aiming Veterinary Surgical Practice - Chronic Effect on Biomechanics and Students’ Evaluation. CPQ Med 4: 1-8.), similar to the findings of this research. In all studies, the salt solution was higher than 20%, as recommended for the efficient conservation of corpses (Friker et al. 2007FRIKER J, ZEILER E & MCDANIEL BJ. 2007. From formalin to salt. Development and introduction on a salt-based preserving solution for macroscopic anatomic specimens. Tierärztl Praxis 35: 243-248.).

High concentration salt solution’s success may be due to the difficulty of microorganisms to survive in a medium that requires an enormous capacity of osmoregulation, as occurs in the dead sea (Nissenbaum 1975NISSENBAUM A. 1975. The microbiology and biogeochemistry of the Dead Sea. Microb Ecol 2: 139-161.).

The use of this technique with CSS and EA did not generate contamination on effluents and the odor is better than formaldehyde or Thiel embalming solution. It is a low-cost alternative to the methods that use formaldehyde (WHO 1991WHO – WORLD HEALTH ORGANIZATION. 1991. IPCS International Programme on Chemical Safety Formaldehyde - Health and Safety Guide 57: 5-44., Janczyk et al. 2011JANCZYK P, WEIGNER J, BECKER AL, KAESSMEYER S & PLENDL J. 2011. Nitrite pickling salt as an alternative to formaldehyde for embalming in veterinary anatomy - A study based on histo and microbiological analyses. Ann Anat - Anat Anz 193: 71-75., Cury et al. 2013CURY FS, CENSONI JB & AMBRÓSIO CE. 2013. Técnicas anatômicas no ensino da prática de anatomia animal. Pesq Vet Bras 33: 688-696.), and an option to fix the corpses to student dissection courses and surgical practicing (Hammer et al. 2014HAMMER N, LÖFFLER S, BECHMANN I, STEINKE H, HÄDRICH C & FEJA C. 2014. Comparison of modified thiel embalming and ethanol-glycerin fixation in an anatomy environment: Potentials and limitations of two complementary techniques. Anat Sci Educ 8: 74-85., Rocha et al. 2019ROCHA TASS, SANTOS CCC, IOZZI MT, DIAS RS, ZERO RC, CARDOZO MV & OLIVEIRA FS. 2019. Chemically prepared dog cadavers in the teaching of surgical technique - evaluation by students of a veterinary medicine course. Acta Sci Anat 1: 136-140.).

The use of formaldehyde to fix corpses causes changes in the color, resistance, and fragility of organs and tissues, making its use limited for surgery training (Groscurth et al. 2001GROSCURTH P, EGGLI P, KAPFHAMMER J, RAGER GJ, HORNUNG P & FASEL JDH. 2001. Gross Anatomy in the Surgical Curriculum in Switzerland: Improved Cadaver Preservation, Anatomical Models, and Course Development. Anat Rec 265: 254-256.). This research provided, without formaldehyde, cat corpses used for one week without significant changes in tissue biomechanics, in addition to the corpses’ softness and tissue malleability.

Biomechanical analysis

In cats weighing 3.58±0.63kg, prepared with the same anatomical technique without vacuum packaging (EA and CSS), and preserved for 90 days, the MRF of skin samples ranged from 254.19±183.25N (fresh/control samples) to 234.68±108.17N (Fração et al. 2019FRAÇÃO VC, ZERO RC, RODRIGUES A, FERREIRA BN, FECHIS ADS, ROCHA TASS, IOZZI MT & OLIVEIRA FS. 2019. Analysis of the Skin of Cats’ Corpses Chemically Prepared with Ethylic Alcohol and Curing Salt Aiming Veterinary Surgical Practice - Chronic Effect on Biomechanics and Students’ Evaluation. CPQ Med 4: 1-8.). In another study with dogs weighing 7.6±2.7kg, preserved with 30% SCAS and fixed with EA up to four months, the maximum rupture force was 106.7N to 177.5N (mean 142.1N) (Rocha et al. 2018ROCHA TASS, YANAGIHARA GR, SHIMANO AC, ROLIM GS, SANTOS CCC, FECHIS ADS & OLIVEIRA FS. 2018. Biomechanical analysis of the skin and jejunum of dog cadavers subjected to a new anatomical preservation technique for surgical teaching. J Plast 30: 16-23.). Our study with cats prepared with CSS and EA, weighing 3.76±1.27kg, the MRF ranged from 344.27±102.23N to 249.70±63.80N after seven days, demonstrating a higher resistance and elasticity of cats’ skin when compared to dogs’. The skin’s flexibility and resistance are mainly dictated by the properties of the corneal layer of the epidermis, and the tensile strength of the skin is considered to be due to type I collagen fibers in the deeper layer of the dermis (Bismuth et al. 2014BISMUTH C, GERIN C, VIGUIER E, FAU D, DUPASQUIER F, CAVETIER L & CAROZZO C. 2014. The biomechanical properties of canine skin measured in situ by uniaxial extension. J Biomech 47: 1067-1073.). The jejunum is composed of smooth musculature that is poor in collagen fibers, becoming less elastic and resistant (Bacha & Bacha 2012BACHA WJ & BACHA LM. 2012. Color Atlas of Veterinary Histology. 3rd ed. Chapter 8, p. 57-64.).

The MRF of chemically prepared cats’ jejunum was 23.39±14.29N, which was similar to the 23.30±9.92N of the same intestine portion, 21.04±9.49N in the duodenum and, 23.82±7.74N in the colon of fresh dog corpses weighting 20.07±8.00kg (Queiroz et al. 2019QUEIROZ ABPS, SOARES LG, VIEIRA GC, DEL PONTI I, FECHIS ADS, ROCHA TASS & OLIVEIRA FS. 2019. Biomechanics Analysis of Duodenum, Jejunum and Colon of Dogs’ Cadavers. CPQ Med 8: 1-5.).

In a study using cats prepared with the same anatomical technique used in our research (EA and CSS) and preserved for 90 days, the MRF of skin samples ranged from 254.19±183.25N (fresh/control samples) to 234.68±108.17N (Fração et al. 2019FRAÇÃO VC, ZERO RC, RODRIGUES A, FERREIRA BN, FECHIS ADS, ROCHA TASS, IOZZI MT & OLIVEIRA FS. 2019. Analysis of the Skin of Cats’ Corpses Chemically Prepared with Ethylic Alcohol and Curing Salt Aiming Veterinary Surgical Practice - Chronic Effect on Biomechanics and Students’ Evaluation. CPQ Med 4: 1-8.). The MRF reached from 344.27±102.23N to 249.70±63.80N after seven days. The difference between research in the MRF must be due to the vacuum packaging presence in our cat corpses. In the vacuum packaging, the air is removed, inactivating the aerobic bacteria, preventing deterioration, leading to a longer storage time and higher product quality. The lack of oxygen causes lactic acid bacteria’s predominance, keeping tissues’ good quality and flexibility (Mantilla et al. 2010MANTILLA SPS, BORGES SM & VITAL H. 2010. Atmosfera modificada na conservação de alimentos. Rev Acad Cienc Agrar Ambient 8: 437-448.).

Microbiological analysis

During the fixation with EA and conservation of cat cadavers with a 30% SCAS, microbiological contamination had remained low (Pereira et al. 2019PEREIRA N, CARDOZO MV, ROCHA TASS, ÁVILA FA, MACHADO MRF & OLIVEIRA FS. 2019. Microbiological analysis of a new anatomical specimen preparation technique for use in veterinary surgery. Semin Cienc Agrar 40: 3099-3106.), similar to the described in this research. The microbial counting of the liquid in packages reached 104 CFU/mL at maximum, which provides adequate health security (BRASIL 2001BRASIL. 2001. Ministério da Saúde (MS). Agência Nacional de Vigilância Sanitária (ANVISA). Resolução RDC nº 12, que aprova o regulamento técnico sobre padrões microbiológicos para alimentos.). In research carried out with pathogen inoculum, the bacteriae concentration that causes disease in the host was 109 CFU/mL (Rigobelo et al. 2016RIGOBELO EC, CARDOZO MV, AVILA FA & BLACKALL PJ. 2016. An evaluation of the use of probiotics and manure composting as strategies to reduce levels of Shiga toxin-producing Escherichia coli in sheep. Afr J 10: 1011-1017.). When using probiotics, the concentration for bacteria to generate the expected benefits should be over 108 UFC/g (Kuru et al. 2017KURU BE, LALEMAN I, YALNIZOGLU T, KURU L & TEUGHELS W. 2017. The influence of Bifidobacterium Animalis Probiotic on gingival health: a randomized controlled clinical trial. J Periodontol 88: 1115-1123.).

This research’s limitation was not to know the precise time corpses were frozen after death so that tissues could be well preserved. However, we did not observe any cadaver with decay signs after thawing, and all of them could be used for injection.

CONCLUSION

This tested anatomical technique proved to be efficient in keeping the biomechanical characteristics of the embalmed cat cadavers. Microbiological analyses were low, demonstrating the possible effectiveness of corpses for surgery training.

REFERENCES

  • ARLUKE A. 2004. The use of dogs in medical and veterinary training: understanding and approaching Student uneasiness. J Appl Anim Welf Sci 7: 197-204.
  • BACHA WJ & BACHA LM. 2012. Color Atlas of Veterinary Histology. 3rd ed. Chapter 8, p. 57-64.
  • BALTA JY, CRONIN M, CRYAN JF & O ́MAHONY SM. 2015. Human Preservation Techniques in Anatomy: A 21st Century Medical Education Perspective. Clin Anat 28: 725-734.
  • BALTA JY, TWOMEY M, MOLONEY F, DUGGAN O, MURPHY KP, O’CONNOR OJ, CRONIN M, CRYAN JF, MAHER MM & O’MAHONY SM. 2018. A comparison of embalming fluids on the structures and properties of tissue in human cadavers. Anat Histol Embryol 47: 1-10.
  • BARROW GI & FELTHAM RKA. 1993. Cowan and Steel ́s. Manual for the identification of medical bacteria. 3rd ed. Cambridge, Cambridge University, 331 p.
  • BARTON DPJ, DAVIES DC, MAHADEVAN V, DENNIS L, ADIB T, MUDAN S, SOHAIB A & ELLIS H. 2009. Dissection of soft-preserved cadavers in the training of gynaecological oncologists: Report of the first UK workshop. Gynecol Oncol 113: 352-356.
  • BISMUTH C, GERIN C, VIGUIER E, FAU D, DUPASQUIER F, CAVETIER L & CAROZZO C. 2014. The biomechanical properties of canine skin measured in situ by uniaxial extension. J Biomech 47: 1067-1073.
  • BRASIL. 2001. Ministério da Saúde (MS). Agência Nacional de Vigilância Sanitária (ANVISA). Resolução RDC nº 12, que aprova o regulamento técnico sobre padrões microbiológicos para alimentos.
  • CALAMARES NETO JE & COLOMBO TE. 2015. Isolamento e identificação de fungos filamentosos em peças anatômicas conservadas em formol. J Health Sci Inst 33: 218-222.
  • CURY FS, CENSONI JB & AMBRÓSIO CE. 2013. Técnicas anatômicas no ensino da prática de anatomia animal. Pesq Vet Bras 33: 688-696.
  • EISMA R, LAMB C & SOAMES RW. 2013. From formalin to Thiel embalming: what changes? One anatomy department’s experiences. Clin Anat 26: 564-571.
  • EISMA R, MAHENDRAN S, MAJUMDAR S, SMITH D & SOAMES RW. 2011. A comparison of Thiel and formalin embalmed cadavers for thyroid surgery training. Surgeon 9: 142-146.
  • FRAÇÃO VC, ZERO RC, RODRIGUES A, FERREIRA BN, FECHIS ADS, ROCHA TASS, IOZZI MT & OLIVEIRA FS. 2019. Analysis of the Skin of Cats’ Corpses Chemically Prepared with Ethylic Alcohol and Curing Salt Aiming Veterinary Surgical Practice - Chronic Effect on Biomechanics and Students’ Evaluation. CPQ Med 4: 1-8.
  • FRIKER J, ZEILER E & MCDANIEL BJ. 2007. From formalin to salt. Development and introduction on a salt-based preserving solution for macroscopic anatomic specimens. Tierärztl Praxis 35: 243-248.
  • GOYRI-O’NEILL J, PAIS D, FREIRE DE ANDRADE F, RIBEIRO P, BELO A, O’NEILL A, RAMOS S & NEVES MARQUES C. 2013. Improvement of the embalming perfusion method: The innovation and the results by light and scanning electron microscopy. Acta Med Port 26: 188-194.
  • GROSCURTH P, EGGLI P, KAPFHAMMER J, RAGER GJ, HORNUNG P & FASEL JDH. 2001. Gross Anatomy in the Surgical Curriculum in Switzerland: Improved Cadaver Preservation, Anatomical Models, and Course Development. Anat Rec 265: 254-256.
  • HAAR G, BUIKS SC, VAN DELDEN M, REIJNTJES T, SANCHEZ RF & KIRPENSTEIJN J. 2013. Skin tension. In: Kirpensteijn J & Haar G. (Eds) Reconstrutive surgery and wound management of the dog and the cat. London, p. 12-14.
  • HAMMER N, LÖFFLER S, BECHMANN I, STEINKE H, HÄDRICH C & FEJA C. 2014. Comparison of modified thiel embalming and ethanol-glycerin fixation in an anatomy environment: Potentials and limitations of two complementary techniques. Anat Sci Educ 8: 74-85.
  • HAMMER N, LÖFFLER S, FEJA C, BECHMANN I & STEINKE H. 2011. Substitution of formaldehyde in cross anatomy is possible. J Natl Cancer Inst 103: 610-611.
  • HAMMER N, LÖFFLER S, FEJA C, SANDROCK M, SCHMIDT W, BECHMANN I & STEINKE H. 2012. Ethanol-glycerin fixation with thymol conservation: A potential alternative to formaldehyde and phenol embalming. Anat Sci Educ 5: 225-233.
  • HART J. 1990. Cadaver preservation and dissection. Eur J Plast Surg 13: 75-78.
  • HAYASHI S ET AL. 2014. Saturated Salt Solution Method: A Useful Cadaver Embalming for Surgical Skills Training. Med J 93: 1-10.
  • HAYASHI S, NAITO M, KAWATA S, QU N, HATAYAMA N, HIRAI S & ITOH M. 2016. History and future of human cadaver preservation for surgical training: from formalin to saturated salt solution method. Anat Sci Int 91: 1-7.
  • IAMARINO LZ, OLIVEIRA MC, ANTUNES MM, OLIVEIRA M, RODRIGUES RO, ZANIN CICB, SCHIMILE M & LIMA AA. 2015. Nitritos e Nitratos em produtos cárneos enlatados e/ou embutidos. Gestão em Foco 7: 246-251.
  • JACINTO MAC, SILVA SOBRINHO AG & COSTA RG. 2004. Características anátomo-estruturais da pele de ovinos (Ovis áries) lanados e deslanados, relacionadas com o aspecto físico-mecânico do couro. R Bras Zootec 33: 1001-1008.
  • JANCZYK P, WEIGNER J, BECKER AL, KAESSMEYER S & PLENDL J. 2011. Nitrite pickling salt as an alternative to formaldehyde for embalming in veterinary anatomy - A study based on histo and microbiological analyses. Ann Anat - Anat Anz 193: 71-75.
  • JAY JM. 2005. Microbiologia de alimentos. 6a ed. Porto Alegre, Artmed.
  • KURU BE, LALEMAN I, YALNIZOGLU T, KURU L & TEUGHELS W. 2017. The influence of Bifidobacterium Animalis Probiotic on gingival health: a randomized controlled clinical trial. J Periodontol 88: 1115-1123.
  • LAFLAMME D. 1997. Development and validation of a body condition score system for cats: a clinical tool. Feline Pract 25: 13-18.
  • MANTILLA SPS, BORGES SM & VITAL H. 2010. Atmosfera modificada na conservação de alimentos. Rev Acad Cienc Agrar Ambient 8: 437-448.
  • NISSENBAUM A. 1975. The microbiology and biogeochemistry of the Dead Sea. Microb Ecol 2: 139-161.
  • OLIVEIRA FS. 2014. Assessing the effectiveness of 30% sodium chloride aqueous solution for the preservation of fixed anatomical specimens: a 5-year follow-up study. J Anat 225: 118-121.
  • PEREIRA N, CARDOZO MV, ROCHA TASS, ÁVILA FA, MACHADO MRF & OLIVEIRA FS. 2019. Microbiological analysis of a new anatomical specimen preparation technique for use in veterinary surgery. Semin Cienc Agrar 40: 3099-3106.
  • QUEIROZ ABPS, SOARES LG, VIEIRA GC, DEL PONTI I, FECHIS ADS, ROCHA TASS & OLIVEIRA FS. 2019. Biomechanics Analysis of Duodenum, Jejunum and Colon of Dogs’ Cadavers. CPQ Med 8: 1-5.
  • RIGOBELO EC, CARDOZO MV, AVILA FA & BLACKALL PJ. 2016. An evaluation of the use of probiotics and manure composting as strategies to reduce levels of Shiga toxin-producing Escherichia coli in sheep. Afr J 10: 1011-1017.
  • ROCHA TASS, SANTOS CCC, IOZZI MT, DIAS RS, ZERO RC, CARDOZO MV & OLIVEIRA FS. 2019. Chemically prepared dog cadavers in the teaching of surgical technique - evaluation by students of a veterinary medicine course. Acta Sci Anat 1: 136-140.
  • ROCHA TASS, YANAGIHARA GR, SHIMANO AC, ROLIM GS, SANTOS CCC, FECHIS ADS & OLIVEIRA FS. 2018. Biomechanical analysis of the skin and jejunum of dog cadavers subjected to a new anatomical preservation technique for surgical teaching. J Plast 30: 16-23.
  • RODRIGUES H. 2010. Técnicas anatômicas. GM Gráfica & Editora. Vitória-ES, 269 p.
  • VANDERZANT C & SPLITTSTOESSER DE. 1992. Compendium of methods for the microbiological examination of foods. 3rd ed. Washington, American Public Health Association, 1219 p.
  • WHO – WORLD HEALTH ORGANIZATION. 1991. IPCS International Programme on Chemical Safety Formaldehyde - Health and Safety Guide 57: 5-44.

Publication Dates

  • Publication in this collection
    07 Jan 2022
  • Date of issue
    2022

History

  • Received
    27 May 2020
  • Accepted
    5 Nov 2020
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