Necropsy Guide for Dogs, Cats,
and Small Mammals

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This book is dedicated to John M. King, who wrote The Necropsy Book, and taught us all about
the art of the necropsy.

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Necropsy Guide for Dogs, Cats,
and Small Mammals
Edited by

Sean P. McDonough

DVM, PhD, Diplomate ACVP
Cornell University
Ithaca, NY

Teresa Southard

DVM, PhD, Diplomate ACVP
Cornell University
Ithaca, NY

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­This edition first published 2017 © 2017 John Wiley & Sons, Inc
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Library of Congress Cataloging‐in‐Publication Data
Names: McDonough, Sean P., editor. | Southard, Teresa, editor.
Title: Necropsy guide for dogs, cats, and small mammals / edited by Sean P. McDonough, Teresa Southard.
Description: Ames, Iowa, USA : John Wiley & Sons Inc., 2017. | Includes bibliographical references and index.
Identifiers: LCCN 2016036895 | ISBN 9781119115656 (pbk.) | ISBN 9781119115670 (ePub) | ISBN 9781119115663 (Adobe PDF)
Subjects: LCSH: Veterinary autopsy. | Dogs–Autopsy. | Cats–Autopsy. | MESH: Autopsy–veterinary | Autopsy–methods |
Dissection–veterinary | Dogs | Cats
Classification: LCC SF769 .N43 2017 | NLM SF 769 | DDC 636.089/60759–dc23
LC record available at />A catalogue record for this book is available from the British Library.
Wiley also publishes its books in a variety of electronic formats. Some content that appears in print may not be available in
electronic books.
Set in 10/12pt Warnock by SPi Global, Pondicherry, India
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v

Brief Contents
List of Contributors  xv
Foreword  xvii
Acknowledgments  xix
About the Companion Website  xxi
Part I 
1
2
3

Introduction to the Necropsy  3

Necropsy Basics   9
The Necropsy Procedure   21
Part II 

4
5
6
7
8
9
10
11
12
13
14

Organ Systems  39

The Integumentary System  41
The Musculoskeletal System  49
The Cardiovascular System  59
The Respiratory System  69
The Alimentary System  77
The Liver and Pancreas  91
The Urogenital System  101
The Nervous System  107
The Eye and Ear  115
The Endocrine System  125
The Lymphoreticular System  133
Part III 


15
16

Necropsy Fundamentals  1

Special Cases  143

Small Mammal Necropsies  145
Fetuses and Neonatal Animals  153

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vi

Brief Contents

Part IV 

Additional Testing  157

17Cytology 
159
18Histopathology 
165
19
Infectious Disease Testing  171
20
Toxicology Testing  175

21
Packaging and Shipping Samples  179
Appendix 1: Normal Organ Weights (Percentage Body Weight)  183
Appendix 2: North American Diagnostic Laboratories  187
Appendix 3: Tissue Collection Checklist  193
Appendix 4: Describing Gross Lesions  195
Index  197

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vii

Contents
List of Contributors  xv
Foreword  xvii
Acknowledgments  xix
About the Companion Website  xxi
Part I 
1

Necropsy Fundamentals  1

Introduction to the Necropsy  3
Sean P. McDonough and Teresa Southard

1.1
What is a Necropsy?  3
1.2­Why do a Necropsy?  3
1.3­What Information Can and Cannot Be Gained from a Necropsy  3

1.4­When to Refer a Necropsy  4
2

Necropsy Basics   9
Sean P. McDonough and Teresa Southard

2.1
Necropsy Facilities  9
2.2
Necropsy Equipment  9
2.3
Safety Considerations  13
2.3.1 Cuts and Punctures  14
2.3.2 Zoonotic Disease  14
2.3.3Formalin 
15
2.4
The Importance of a Good History  15
2.5
The Necropsy Report  15
2.5.1 Gross Description  15
2.5.2 Gross Findings  16
2.5.3 Gross Diagnosis  16
2.5.4Comment 
16
2.6
Postmortem Changes  16
3

The Necropsy Procedure   21

Sean P. McDonough and Teresa Southard

3.1Introduction 
21
3.2
Weigh the Body  21

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viii

Contents

3.3
External Examination  21
3.4
Reflect the Skin and Right Limbs   22
3.5
Open the Abdominal Cavity  26
3.6
Puncture the Diaphragm  27
3.7
Open the Thoracic Cavity  27
3.8
Open the Pericardium  28
3.9
In Situ Examination of Organs   29
3.10
Remove the Adrenal Glands  30

3.11
Remove the Pluck  30
3.12
Remove the Gastrointestinal Tract, Liver, and Spleen  32
3.13
Remove the Urogenital Organs  34
3.14
Remove the Head   35
3.15
Take Out the Eyes  35
3.16
Remove the Brain   36
3.17
Remove the Pituitary Gland   37
Bibliography  37
Part II 
4

Organ Systems  39

The Integumentary System  41
Jeanine Peters-Kennedy

4.1
Anatomy Review  41
4.1.1 External Ear Canal Anatomy  42
4.2
In Situ Examination and Removal  42
4.2.1 Primary Lesions  42
4.2.2 Lesions that May Be Primary or Secondary  43

4.2.3 Secondary Skin Lesions  43
4.3
Organ Examination, Sectioning, and Fixation  44
4.3.1 Cytology   44
4.3.2 Skin Scrapes  44
4.3.3 Hair Examination (Trichogram)  44
4.3.4 Examination of the External Ear Canal  44
4.3.5 Sampling the Skin  45
4.4
Common Artifacts and Postmortem Changes  46
Bibliography  46
5

The Musculoskeletal System  49
Teresa Southard

5.1
Anatomy Review  49
5.1.1 Bones and Joints  49
5.1.2Teeth 
51
5.1.3 Skeletal Muscle  52
5.2
In Situ Evaluation, Sectioning, and Fixation  52
5.2.1Bones 
52
5.2.2 Joints, Tendons, and Ligaments  54
5.2.3 Skeletal Muscle  55

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Contents

5.3
Special Techniques  55
5.3.1 Postmortem Imaging  55
5.3.2 Cleaning Bones  56
5.3.3 India Ink Evaluation of Articular Cartilage  56
5.3.4 Examining the Intervertebral Discs  56
5.3.5 Submitting Muscle for Additional Tests  56
5.4
Common Artifacts and Postmortem Changes  56
Bibliography  57
6

The Cardiovascular System  59
Kathleen M. Kelly

6.1
Anatomy Review  59
6.1.1 Right Heart   59
6.1.2 Left Heart  60
6.1.3 Vessels: Great and Small  60
6.1.4 Contextual Cardiac Embryology and Congenital Heart Malformations  62
6.2
In Situ Evaluation and Removal  63
6.3
Organ Examination, Sectioning, and Fixation  64
6.4

Common Artifacts, Non-lesions, and Postmortem Changes   66
Bibliography   68
7

The Respiratory System  69
Elizabeth L. Buckles and Teresa Southard

7.1
Anatomy Review  69
7.2
In Situ Evaluation and Removal  71
7.3
Organ Examination, Sectioning, and Fixation  72
7.3.1 Larynx and Trachea  72
7.3.2Lungs 
73
7.3.3 Nasal Cavity and Sinuses  74
7.4
Special Techniques  74
7.5
Common Artifacts and Postmortem Changes  75
Bibliography  75
8

The Alimentary System  77
Gerald E. Duhamel

8.1
8.1.1
8.1.2

8.1.3
8.1.4
8.1.5
8.1.6
8.1.7
8.2
8.2.1
8.2.2
8.3

Anatomy Review  77
The Oropharyngeal Cavity  77
The Salivary Glands   78
The Esophagus   78
The Stomach   79
The Small Intestine  79
The Large Intestine  81
The Intestinal Vasculature and Nervous System  82
In Situ Evaluation and Removal  82
The Esophagus   83
The Gastrointestinal Tract  83
Organ Examination, Sectioning, and Fixation  85

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x


Contents

8.3.1 Gastrointestinal Tract  85
8.4
Special Techniques  87
8.5
Common Artifacts and Postmortem Changes  88
Bibliography  89
9

The Liver and Pancreas  91
Sean P. McDonough

9.1
Anatomy Review  91
9.1.1 The Liver   91
9.1.2 The Pancreas  93
9.2
In Situ Evaluation and Removal  94
9.2.1 The Liver  94
9.2.2 The Pancreas  96
9.3
Organ Examination, Sectioning, and Fixation  96
9.3.1 The Liver  96
9.3.2 The Pancreas  98
9.4
Common Artifacts and Postmortem Changes  98
9.4.1 The Liver  98
9.4.2 The Pancreas  99
Bibliography  99

10

The Urogenital System  101
Teresa Southard

10.1
Anatomy Review  101
10.2
In Situ Evaluation and Removal  103
10.3
Organ Examination, Sectioning, and Fixation  103
10.3.1Kidneys 103
10.3.2Ureters 104
10.3.3 Bladder and Urethra  104
10.3.4Ovaries 105
10.3.5Oviduct/Uterus/Cervix/Vagina 105
10.3.6 Testes/Epididymides/Ductus Deferens  105
10.3.7 Prostate Gland  105
10.3.8 Bulbourethral Gland (Cats Only)  106
10.3.9 Distal Colon/Rectum/Anus  106
10.4
Special Techniques  106
10.5
Common Artifacts and Postmortem Changes  106
Bibliography  106
11

The Nervous System  107
Andrew D. Miller


11.1
Anatomy Review  107
11.2
In Situ Evaluation and Removal  108
11.2.1Brain 108
11.2.2 Spinal Cord  109
11.2.3 Peripheral Nerves  110
11.3
Organ Examination, Sectioning, and Fixation  110
11.3.1Brain 110

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Contents

11.3.2 Spinal Cord  112
11.3.3Nerves 112
11.4
Common Artifacts and Postmortem Changes  112
Bibliography  113
12

The Eye and Ear  115
Sean P. McDonough

12.1
The Eye   115
12.1.1 Anatomy Review  115
12.1.2 In Situ Evaluation and Removal  115

12.1.3 Examination, Sectioning, and Fixation  117
12.2
The Ear  119
12.2.1 Anatomy Review  119
12.2.2 In Situ Evaluation and Removal  122
12.2.3 Examination, Sectioning, and Fixation  122
Bibliography  123
13

The Endocrine System  125
Sean P. McDonough

13.1
13.1.1
13.1.2
13.1.3
13.1.4
13.2
13.2.1
13.2.2
13.2.3
13.2.4
13.3
13.3.1
13.3.2
13.3.3
13.3.4
13.4

Anatomy Review  125

The Pituitary Gland  125
The Thyroid and Parathyroid Glands  125
The Endocrine Pancreas (Islets of Langerhans)  126
The Adrenal Glands  126
In Situ Evaluation and Removal  127
The Pituitary Gland  127
The Thyroid and Parathyroid Glands  128
The Endocrine Pancreas  129
The Adrenal Glands  130
Organ Examination, Sectioning, and Fixation  130
The Pituitary Gland  130
The Thyroid and Parathyroid Glands  131
The Endocrine Pancreas  131
The Adrenal Glands  131
Common Artifacts and Postmortem Changes  132

14

The Lymphoreticular System  133
Sean P. McDonough

14.1
Anatomy Review  133
14.1.1Thymus 133
14.1.2 Lymph Nodes  133
14.1.3Spleen 133
14.1.4 Bone Marrow  135
14.2
In Situ Evaluation and Removal  135
14.2.1Thymus 135

14.2.2 Lymph Nodes  136
14.2.3Spleen 136
14.2.4 Bone Marrow  138

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xii

Contents

14.3
Organ Examination, Sectioning, and Fixation  138
14.3.1Thymus 138
14.3.2 Lymph Nodes  138
14.3.3Spleen 140
14.3.4 Bone Marrow  140
14.4
Incidental Findings  141
Part III 
15

Special Cases  143

Small Mammal Necropsies  145
Teresa Southard

15.1

Species Differences  145
15.2
Necropsy Technique   145
Bibliography  151
16

Fetuses and Neonatal Animals  153
Teresa Southard

16.1Anatomy 
153
16.1.1Placenta 153
16.1.2 Umbilical Cord  153
16.1.3 Fetal Circulation   153
16.2
Necropsy Technique  154
16.3
Common Artifacts and Postmortem Changes  156
Part IV 

Additional Testing  157

17Cytology 
159
Teresa Southard

17.1
Types of Cytology Preparations  159
Making a Touch Imprint  159
17.2

17.3
Making a Bone Marrow Smear  159
17.4
Other Preparations  160
17.5Staining 
160
17.6
Atlas of Normal Tissues  161
18Histopathology 
165
Sean P. McDonough and Teresa Southard

18.1
Necropsy Samples for Histopathology  165
18.2Fixation 
165
18.3
Practical Guidelines to Optimize Fixation  168
19

Infectious Disease Testing  171
Teresa Southard

19.1
19.2

Test Types  171
Aerobic Culture  171

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Contents

19.3
Anaerobic Culture  173
19.4
Fungal Culture  173
19.5
Fluorescent Antibody Tests  174
19.6PCR 
174
19.7ELISA 
174
19.8
Virus Isolation  174
19.9
Qualitative Fecal  174
19.10Immunohistochemistry 174
20

Toxicology Testing  175
Teresa Southard

Bibliography  175
21

Packaging and Shipping Samples  179
Sean P. McDonough


21.1
Packing Samples to Send to the Lab  180
Bibliography  180
Appendix 1: Normal Organ Weights (Percentage Body Weight)  183
Appendix 2: North American Diagnostic Laboratories  187
Appendix 3: Tissue Collection Checklist  193
Appendix 4: Describing Gross Lesions  195
Index  197

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xiii


xv

List of Contributors
Elizabeth L. Buckles, DVM, PhD, Diplomate ACVP

Andrew D. Miller, DVM, Diplomate ACVP

Department of Biomedical Sciences
College of Veterinary Medicine
Cornell University

Department of Biomedical Sciences
College of Veterinary Medicine
Cornell University

Gerald E. Duhamel, DVM, PhD, Diplomate ACVP


Jeanine Peters‐Kennedy, DVM, Diplomate ACVP,
Diplomate ACVD

Department of Biomedical Sciences,
College of Veterinary Medicine,
Cornell University
Kathleen M. Kelly, DVM, PhD, Diplomate ACVP

Department of Biomedical Sciences
College of Veterinary Medicine
Cornell University

Department of Biomedical Sciences
College of Veterinary Medicine
Cornell University

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xvii

­Foreword
“Internists know everything and do nothing;
Surgeons know nothing and do everything;
Pathologists know everything and do everything, but it’s too late.”
This saying is popular among veterinary and
medical students and reflects some common
stereotypes about the different disciplines in
our professions. We will let the internists and

surgeons speak for themselves, but as pathologists, we like to think that our knowledge base is
equivalent to an internist and our technical
skills rival those of a surgeon. And we concede
that our efforts are not going to help the patient
on the necropsy table; however, the work of the
pathologist is not too late to make a big impact.
A necropsy examination is a simple, cost‐effective,
broad spectrum diagnostic procedure that
requires no advanced training or high priced
equipment and can provide information beneficial to the animal’s family and veterinary team,
as well our overall understanding of disease processes (animal and human), which could potentially save other lives.
Despite the benefits of a necropsy, this procedure is rarely performed, and often not even
considered. Here at Cornell, only a small percentage of the animals that die or are euthanized
in the small animal hospital are submitted for
necropsy. In human medicine, the autopsy rate
has drastically declined over the past few decades. Before the 1970s, 30–40% of all human
hospital deaths were investigated by autopsy but
by 2005, the rate had fallen to less than 10%, with
almost no autopsies performed at hospitals that
are not affiliated with an academic institution.

Necropsies are not performed for a variety of
reasons. The death of a companion animal is
always an emotional time and broaching the
subject of a necropsy may seem insensitive.
However, input from the clinicians at the
Cornell University Hospital for Animals suggests that if owners believe something positive
can come from the death of their pet, especially knowledge that could potentially help
other animals, they are much more likely to
consent to a postmortem examination. Also,

many veterinarians, especially at tertiary care
facilities, share the belief of physicians that the
advent of  newer diagnostic techniques and
powerful imaging modalities makes the necropsy or autopsy obsolete. However, despite
the advances in medical technology, the rate of
diagnostic errors remains high. Up to 10% of
autopsies reveal a misdiagnosis that would
likely have affected patient outcome and the
cause of death is misdiagnosed in almost 25% of
cases. Our personal experience with necropsies
reveals similar percentages of misdiagnoses in
veterinary medicine.
The goal of this book is to provide veterinary
students and small animal practitioners, as well
as pathology residents and pathologists, a guide
for performing a necropsy, including a step‐by‐
step tutorial of the basic necropsy procedure, a
review of the anatomy and dissection techniques for each organ system, and information
on collecting tissues for additional testing. We
hope more veterinarians will take advantage of
the unique continuing educational opportunity
the necropsy affords them.

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xix

­Acknowledgments
We are grateful to everyone who helped make

this book a reality, particularly Jodie Gerdin,
who got this whole project started; Karyn
Bischoff, James Morrisey, Ashleigh Newman,
Pamela Schenck, Belinda Thompson, and
Jimmy Tran, who contributed their knowledge,
time and resources; and the Cornell pathology

residents and necropsy students who were
patient with us as we interrupted their work to
take pictures. Photograph contributors for this
book include: Don Schlafer, Ana Alcaraz, Roger
Panciera, Gavin Hitchener, May Tse, Nick
Vitale, Jimmy Tran, Stacy Rine, Alex Molesan,
and Heather Daverio.

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xxi

­About the Companion Website
This book is accompanied by a companion website:

www.wiley.com/go/mcdonough/necropsy
The website includes:
●●

Video of necropsy being performed.

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1

Part I
Necropsy Fundamentals

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3

1
Introduction to the Necropsy
1.1 ­What is a Necropsy?
A necropsy is a postmortem examination. By
convention, this term is typically used to denote
a postmortem examination of a non‐human
animal, and the term “autopsy” is used for a
postmortem examination of a human; however,
the terms are essentially interchangeable, and
some veterinary pathologists have argued for
the use of a common term to increase communication in the age of “one medicine,” Both terms
are derived from Greek words: autopsy is from
the word autopsia, meaning the act of seeing for
one’s self; necropsy is from the words nekros
meaning dead and the suffix ‐opsis meaning
sight. The word autopsy was used in the 1600s,
and the word necropsy did not appear until
about 200 years later, most likely to replace the

two‐word term autopsia cadavaria, or to look
for oneself at a dead body. We chose the term
necropsy for this book because it is the term we
use at Cornell, where the word is deeply rooted
in the long‐standing tradition of veterinary
pathology.
The term necropsy can be used broadly to
encompass the entire set of diagnostic procedures that occur after an animal dies; however,
in this book we will use the term to denote the
macroscopic or gross examination of the carcass and the process of collecting tissues for histopathology and other ancillary tests. At Cornell
and most diagnostic laboratories, the fee for a
necropsy includes both gross examination and
microscopic evaluation of the tissues collected

during the necropsy; however, for a reduced fee,
the formalin fixed tissues collected by a referring veterinarian or scientist can be processed
and examined histologically (we call this type of
case a “necropsy in a bottle”). If the clinician is
willing to do the necropsy and collect the
­tissues, the necropsy in a bottle option is often
an economically attractive alternative to shipping the carcass to a diagnostic lab.
In this text, the term prosector will be used for
the person performing the necropsy.

1.2 ­Why do a Necropsy?
Necropsies are performed to determine or confirm the cause of death or reason for a condition
necessitating euthanasia. A necropsy may be
requested by an owner, a veterinarian, a drug or
vaccine company, a biomedical researcher, or a
law enforcement or other government agency.

The common reasons for necropsy requests at
Cornell are shown in Table 1.1.

1.3 ­What Information Can
and Cannot Be Gained
from a Necropsy
A necropsy can result in a definitive diagnosis, a
presumptive diagnosis or, if there are no gross
lesions, will at least rule out some possible
diagnoses.

Necropsy Guide for Dogs, Cats, and Small Mammals, First Edition. Edited by Sean P. McDonough and Teresa Southard.
© 2017 John Wiley & Sons, Inc. Published 2017 by John Wiley & Sons, Inc.
Companion Website: www.wiley.com/go/mcdonough/necropsy

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4

Necropsy Guide for Dogs, Cats, and Small Mammals

Table 1.1  Reasons necropsies are requested.
Owner

Gain peace of mind, especially about a decision to euthanize
Rule in or out infectious/toxic cause when other animals are at risk
Suspicion of malicious action by another party (usually the
neighbor)
Suspicion of veterinary malpractice

Concern about zoonotic disease (rabies)
Insurance reasons (most common in horses)

Veterinarian

Find answers in a confusing or atypical case
Confirm a suspected diagnosis
Examine surgical sites or retrieve implanted devices
Collect data about a condition of interest

Drug or Vaccine Company

Determine if drug or vaccine caused illness or death

Biomedical Researcher

Investigate cause of unexpected death in animal on a study
Compare control and experimental animals at end of study

Law Enforcement or Government Agency

Animal harmed or killed during police activity
Suspicion of criminal cruelty or neglect
Suspicion of a pet‐food related toxicity

Necropsies are particularly rewarding when
they reveal pathognomonic gross lesions. These
gross changes are specific for a particular disease entity and can often allow the prosector to
make a definitive diagnosis with no need for
additional testing. Some of these conditions are

illustrated in Figures 1.1–1.6. Unfortunately,
these cases make up only about 10% of our caseload at Cornell.
In another small portion of cases, again
roughly 10%, the necropsy reveals no lesions to
suggest a cause of death, either because all
organs are grossly normal or because the body is
decomposed to the point that lesions cannot be
distinguished from the processes of decay.
Abortions and neonatal deaths are our lowest
yield necropsies, and often these cases go unresolved even with complete ancillary testing.
Causes of death that typically have minimal or
no gross lesions include metabolic derangements, many toxicities (especially neurotoxins),
and cardiac arrhythmias.
For the vast majority of cases, the necropsy
provides some clues as to the disease process,
allows for a presumptive diagnosis, and directs
sampling for additional tests that, in many cases,
will yield a definitive diagnosis.

1.4 ­When to Refer a Necropsy
Anyone who has a good grasp of normal veterinary anatomy can perform a necropsy (especially if they read this book!) No advanced
training is required; however, before beginning,
a practitioner should make a realistic assessment
of their ability to perform a particular necropsy.
There are certain types of necropsies that are
best handled by specialists in facilities specifically designed for postmortem examinations.
Necropsies should be referred to a diagnostic
laboratory with board certified pathologists in
the following circumstances:
1)  Cases where a client expresses concerns

about your veterinary care of the patient
2)  Cases which are part of a legal dispute
(forensic necropsy)
3)  Cases with strong suspicion of a zoonotic
agent, such as rabies or tularemia
4)  Cases involving unfamiliar species, such as
non‐human primates, reptiles, and birds.
Veterinarians sometimes open up the body
to look for obvious gross lesions and, if none
are detected, pack up the opened carcass and
send it to us for a “second look necropsy.”

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Chapter 1: Introduction to the Necropsy

Figure 1.1  Segmental hemorrhagic enteritis in this 8‐week‐old kitten is virtually diagnostic for panleukopenia
caused by feline parvovirus. The lesion in puppies with canine parvovirus infection is similar.

Figure 1.2  The wet form of feline infectious peritonitis often causes bright yellow, thick peritoneal effusion and
multifocal tan to white plaques on the serosal surfaces.

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Necropsy Guide for Dogs, Cats, and Small Mammals

Figure 1.3  Dark red foci on the capsular surface of the kidneys in a newborn puppy usually indicates infection with
canine herpesvirus.

Figure 1.4  The gross finding of a distended, rotated, congested stomach is characteristic of gastric dilatation
volvulus in a dog.

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Chapter 1: Introduction to the Necropsy

Figure 1.5  Long, slender tan nematode parasites in the right side of the heart and pulmonary artery are
pathognomonic for heart worm infection (dirofilariasis).

Figure 1.6  A dark red mass associated with the right atrium, with or without rupture and hemopericardium, in a dog
strongly supports a diagnosis of hemangiosarcoma.

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Necropsy Guide for Dogs, Cats, and Small Mammals

Opening the body cavities leads to significant
artifactual changes in the color and consistency of the viscera and may interfere with

both  gross interpretation of lesions and the
ability to collect optimal samples for additional

t­ esting. The preferred course of action at this
point would be to continue with the necropsy,
take digital photos, and send us the photos
along with formalin‐fixed (and fresh, if appropriate) samples.

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