Veterinary Necropsy Glossary for Domestic Animals
A comprehensive terminology guide for necropsy practice in companion and domestic animals.
A
- Abdominal cavity – The space within the abdomen containing digestive organs, liver, spleen, kidneys, and other structures.
- Abomasum – The fourth or true stomach in ruminants, examined for ulcers, parasites, and other pathology.
- Abscess – A localized collection of pus found in tissues, indicating bacterial infection.
- Acute death – Death occurring rapidly, often with minimal gross lesions visible at necropsy.
- Adipose tissue – Fat tissue examined for distribution, color, and consistency.
- Adrenal glands – Small endocrine glands located near the kidneys, examined for size, hemorrhage, or neoplasia.
- Aerophagia – Swallowing of air, which may cause gastric dilation observable at necropsy.
- Agonal changes – Post-mortem changes occurring at the very time of death (e.g., agonal gasping or hemorrhages), not representing the primary disease process.
- Air embolism – Presence of air bubbles in blood vessels, which may be detected during necropsy.
- Alimentary tract – The digestive system from mouth to anus, systematically examined.
- Algor mortis – The cooling of the body after death, used to estimate the post-mortem interval.
- Anasarca – Generalized subcutaneous edema found throughout the body.
- Anemia – Condition of reduced red blood cells, evident by pale mucous membranes and organs.
- Antemortem – Occurring before death. Findings in this category represent clinical signs or injuries sustained while the animal was alive.
- Aorta – The main artery examined for rupture, atherosclerosis, or parasites.
- Ascites – Accumulation of fluid in the abdominal cavity, measured and characterized.
- Asphyxia – Death from lack of oxygen, with findings including congestion and petechiae.
- Atelectasis – Collapsed or non-expanded lung tissue.
- Atrophy – Decrease in organ or tissue size observed and measured.
- Autolysis – Self-digestion of tissues by enzymes after death, which can mask real lesions.
- Autopsy – Literally “to see for oneself.” While commonly used for humans, in a veterinary context, it is often used interchangeably with necropsy, though “necropsy” is technically more accurate for non-human species.
B
- Bile duct – Duct carrying bile from liver to intestine, examined for obstruction or inflammation.
- Biliary system – Liver, gallbladder, and bile ducts examined together.
- Biopsy – The removal and examination of tissue from a living body for diagnostic purposes. This differs from necropsy as the subject is alive at the time of sampling.
- Bladder – Urinary bladder examined for stones, inflammation, rupture, or neoplasia.
- Blood clot – Coagulated blood; distinguished from ante-mortem thrombi by its “chicken fat” or “currant jelly” appearance and lack of attachment to vessel walls.
- Body cavity – Any of the major cavities (thoracic, abdominal, pelvic) opened during necropsy.
- Bone marrow – Tissue within bones examined for evidence of disease or toxicity.
- Brain – Central nervous system organ requiring careful removal (craniotomy) and examination.
- Bronchi – Airways examined for inflammation, fluid, parasites, or foreign material.
- Bruising – Hemorrhage in tissues; must be distinguished from post-mortem lividity (livor mortis).
C
- Cachexia – Severe wasting of the body observed during external examination.
- Carcinoma – Malignant tumor of epithelial origin.
- Cardiac tamponade – Fluid or blood accumulation in the pericardial sac compressing the heart.
- Caseous necrosis – A form of tissue death resulting in a “cheesy” appearance, often seen in tuberculosis or certain fungal infections.
- Caudal – Directional term meaning toward the tail.
- Cecum – Part of the large intestine examined in herbivores and some other species.
- Cerebellum/Cerebrum – Specific portions of the brain examined for lesions or swelling.
- Chronic disease – Long-standing conditions with findings like fibrosis or organ shrinkage.
- Cirrhosis – End-stage liver disease characterized by fibrosis and nodular regeneration.
- Coagulation necrosis – Type of tissue death where the architecture of the tissue is maintained for days.
- Congestion – Passive accumulation of blood in vessels, often due to heart failure or gravity.
- Coalescing: Multiple individual lesions that are growing together to form one large area.
- Cranial – Directional term meaning toward the head.
- Cyanosis – Bluish discoloration of tissues indicating poor oxygenation before death.
D–F
- Decomposition – Post-mortem breakdown of tissues by bacteria and enzymes.
- Diaphragm – Muscle separating thoracic and abdominal cavities; checked for “negative pressure” upon opening the chest.
- Ecchymosis – Larger area of hemorrhage (bruising), larger than petechiae.
- Emaciation – Extreme thinness with loss of both muscle and fat.
- Encephalomalacia – Abnormal softening of brain tissue.
- Endocarditis – Inflammation of the inner lining of the heart, often appearing as “vegetations” on valves.
- Evisceration – The systematic removal of internal organs for examination.
- Exudate – Inflammatory fluid (rich in protein/cells) found in cavities.
- Fat necrosis – Hard, white, “soapy” deposits in fat tissue, often associated with pancreatitis.
- Fixation – The process of preserving tissue (usually in 10% buffered formalin) to prevent autolysis.
- Friable – Tissue that tears or crumbles easily under light pressure.
G–L
- Gross examination – Visual inspection of the body and organs with the naked eye.
- Hemoabdomen – The presence of free blood in the abdominal cavity.
- Histopathology – The microscopic examination of stained tissue sections on slides.
- Hypertrophy – Increase in the size of an organ due to the enlargement of its component cells.
- Hypostasis (Livor mortis) – The pooling of blood in the lower (dependent) parts of the body after death.
- Icterus (Jaundice) – Yellow staining of tissues (intima of arteries, fat, sclera) by bilirubin.
- In situ – Examining organs in their original anatomical position before they are removed.
- Intussusception – The slipping of one part of the intestine into the lumen of an adjoining part.
- Lesion – Any abnormality in a tissue caused by disease or trauma.
- Lymph node – Small organs of the immune system; reactive nodes are often enlarged and moist.
M–P
- Meninges – The three membranes covering the brain and spinal cord.
- Metastasis – The spread of a disease process (usually cancer) from one organ to another.
- Mucosa – The mucous membrane lining of the respiratory, digestive, and urogenital tracts.
- Myocardium – The muscular tissue of the heart.
- Necropsy – The systematic professional examination of a dead animal to determine the cause of death, the extent of disease, or for scientific study.
- Neoplasia – New, uncontrolled growth of cells (tumors).
- Parenchyma – The functional part of an organ, as opposed to the supporting framework (stroma).
- Pathogenesis – The sequence of events that leads to the development of a disease.
- Petechiae – Tiny, pin-point hemorrhages (less than 3mm).
- Postmortem – Occurring after death. Postmortem changes (like rigor mortis or autolysis) must be distinguished from antemortem lesions.
- Prosector – The individual performing the necropsy.
- Putrefaction – Decomposition of organic matter by bacteria, resulting in foul odors and gas.
R–Z
- Rigor mortis – The stiffening of muscles after death due to chemical changes in the muscle fibers.
- Saponification – The process of fat turning into a soap-like substance during fat necrosis.
- Septicemia – Systemic disease caused by the presence of pathogenic microorganisms or their toxins in the blood.
- Stryker saw – An oscillating saw used to cut through bone (especially the skull) without damaging soft tissue.
- Thoracic cavity – The chest cavity containing the heart and lungs.
- Transudate – Clear, low-protein fluid that leaks out of vessels (e.g., in heart failure).
- Ventral – Relating to the underside or belly of the animal.
- Viscera – The internal organs of the body cavities.
- Zoonotic disease – A disease that can be transmitted from animals to humans; requires high-level biosafety during necropsy.
Descriptors (How to “Speak” Pathology)
To provide a professional report, a pathologist uses specific descriptors for the color, size, and distribution of lesions:
- Coalescing: Multiple individual lesions that are growing together to form one large area.
- Diffuse: A lesion that involves an entire organ or an entire anatomical area uniformly.
- Dystrophic Calcification: Deposition of calcium in dead or dying tissues (with normal blood calcium levels).
- Focal: A single, discrete lesion in one specific spot.
- Locally Extensive: A lesion that covers a large area but is not truly diffuse.
- Multifocal: Multiple “spots” or areas of disease separated by normal tissue.
- Pathognomonic: A lesion or sign that is so specific it leaves no doubt about the diagnosis (e.g., Negri bodies in the brain are pathognomonic for Rabies).
Specialized Findings
- Exsanguination: The process of “bleeding out.” At necropsy, this is evidenced by extremely pale (blanched) organs and very little blood in the heart/vessels.
- Fixation: The process of placing tissue in a preservative (usually 10% Neutral Buffered Formalin) at a 1:10 ratio (one part tissue to ten parts fluid) to stop autolysis.
- Gangrene: A form of tissue death usually involving an extremity; can be “dry” (mummification) or “wet” (bacterial putrefaction).
- Ghost Outlines: A microscopic term for cells that have died but still hold their structural shape, often seen in coagulation necrosis.
Post-Mortem Phenomena
- Postmortem: Occurring after death. This includes all “artifacts” like cooling, stiffening, and decay.
- Post-Mortem Interval (PMI): The estimated time that has elapsed since the animal died.
- Pseudomelanosis: A green-to-black discoloration of tissues (especially the liver and kidneys) caused by bacterial action on blood after death; often confused with bruising.
- Saponification: The process of fat turning into a hard, soapy substance (adipocere) during decomposition or fat necrosis.
- Stenosis: An acquired or congenital narrowing of a tube or valve (e.g., pulmonary stenosis).
Specialized Terms
- Toxicopathology: The study of disease processes and lesions caused by toxins or poisons.
- Vegetation: A cauliflower-like growth on heart valves, typically indicating bacterial endocarditis.
- Volvulus: A specific type of torsion where the intestine or stomach twists on its long axis, usually cutting off blood supply.
Visualizing Necropsy Layout
In a professional setting, the procedure follows a strict “In Situ” evaluation before the organs are removed.