The Ethics of Dissections

by Kevin Haussler, DVM, DC, PhD

I have lost count of the number of animal dissections that I have done over my career for the purpose of teaching anatomy to veterinary students or for acquiring post-mortem information on the necropsy floor. The one thing that has been consistent over the years is that visualizing the animal body under its skin enclosure continues to be a spiritual experience for me and a thing of wonder.

I am especially drawn to bones, specifically vertebrae. I don’t know when this happened, but I find it the most fascinating thing that there is – all the different sizes, shapes, different configurations, interlocking features, protrusions, articular surfaces, and dramatic changes in function from head to tail.

My library is filled with human and veterinary anatomy textbooks – both old and new. The illustrations are always a thing of awe and inspiration. I always find comfort flipping through the pages searching for a specific insertion or innervation. I have confidence in the information that I find there.

example image of a dissection

tall stack of veterinary anatomy books

set of veterinary anatomy books on a shelf

tall stack of veterinary anatomy books on a shelf

Horse dissection courses

Only recently have I become aware that equine dissection courses are being advertised online, with open enrollment for non-veterinarians. This seemed quite unusual to me as I am accustomed to seeing animal dissection typically made available only to veterinary students in their first year of education or in select veterinary, farrier, or dental continuing education courses.

I have also noted the popularity of displaying dissection images on social media and reporting the clinical significance of perceived pathologic findings.

The first points that I clearly want to state are:

  1. I support quality education and increased awareness of anatomical features.
  2. Dissection does not necessarily need to be taught by an anatomist. (See #1)
  3. Animal dissection does not need to be taught by a veterinarian. (See #1)
  4. A course taught by a veterinary anatomist or someone specifically trained in equine anatomy would likely be of higher quality.

Here are some issues that I would want to consider were I to enroll in one of these dissection courses:

  • Educational institutions require informed consent of the owner and strict ethical protocols for acquiring, humane handling, use, and disposal of animals used for live and cadaveric teaching purposes. How are the horses for these online and in-person courses being acquired? Are the carcasses and associated fluids disposed of properly?
  • Are these courses subject to an external ethical review or oversight by a veterinarian or persons in authority?
  • What type of facilities are available to house and display fresh horse carcasses to allow ready and safe access for dissection and teaching purposes? Whole-body refrigeration does not seem feasible in most settings. How is tissue preservation being provided for an extended course?
  • What zoonotic disease education is being provided to prevent disease transmission from animal to humans? What personal protective equipment, first aid kits, and biohazard disposal are available?
  • What is the training and qualifications of the instructors?
  • What is the expected instructor-to-participant ratio?
  • What are the consumer expectations? Is the course designed to be didactic only or is there a substantial portion of the course devoted to hands-on learning?
  • What is the depth and breadth of material taught? What type of supportive educational or reading material is made available to participants?
  • Are the anatomical structures accurately identified and the clinically relevant structural-functional relationships discussed?
  • Are the viscera also included? If so, why? How does this fit into a bodyworker’s scope of practice?
  • How are anatomical variants presented? How are perceived pathologic findings interpreted? Is any clinical relevance assigned to the observed abnormalities? If the anatomical variants or pathologic findings are assigned some level of clinical relevance, how reliable is the clinical history that has been provided for the case?

Correlating anatomical and clinical findings

One of the biggest challenges in veterinary medicine is correlating what we see on radiographs, dried-out bones, or fresh anatomical dissections back to the reported clinical signs.

Owner complaints can be vague and poorly defined – “my horse is stiff when turning to the right”.

Similarly, clinical signs are often nebulous and poorly localized – generalized back pain and muscle atrophy.

And once identified, a clinical sign can be caused by many different issues – for example, there is a long list of issues that can contribute to head tossing, which can include dental issues, poor bit fit or use, anxiety, training-related, photic headshaking, or poll pain.

The diagnostic process is designed to work in a forward, linear progression starting from the owner complaint, to acquiring a medical and performance history, detailed observation, physical localization of clinical signs, diagnostic tests, assessment of findings, considered differential diagnoses, and proposed treatment options.

Unfortunately, what I have observed is that a bony specimen with a perceived defect is presented to the audience and we are then told what clinical signs the horse had.

This scenario is only valid if a complete medical history and physical examination accompanied the horse prior to euthanasia and harvesting the bony specimen.

However, when a bony or soft tissue specimen is presented with little or no supporting clinical history or an apparent lack of basic musculoskeletal physiology, then the stated clinical relevance of the pathologic lesions can be plagued by several common logic traps or faulty assumptions.

Common logic traps and faulty assumptions

  1. The diagnostic process is run in reverse, i.e., the specimen dictates the clinical signs. For example, radiographic findings of osteoarthritis are notorious for being poorly correlated to clinical signs. Horses can have moderate radiographic evidence of cervical articular process osteoarthritis and actively perform at high levels of competition. Other horses can have little to no visible boney changes in their hocks and yet be very lame.
  2. If reported, the clinical signs in the record may have nothing at all to do with the observed boney changes, e.g., the horse died from colic, not musculoskeletal disease. In other circumstances, there is an absent or incomplete owner history, clinical examination, or report of findings. Or the medical history or clinical signs might be embellished to highlight the perceived importance of the displayed bony findings.
  3. Clinical signs can be nebulous and poorly localized. Clinical signs within the axial skeleton are not typically localized to a specific lesion or bone of interest. Impinged spinous processes often affect multiple vertebral levels and it is usually difficult to isolate which exact location is the most significant source of pain or dysfunction.
  4. Clinical signs are variable and can vary within and between animals.
    • A disease process in one limb may not be painful at all but severely painful in the opposite limb, and then may show clinical signs in a different body region the next day.
    • A disease process within one patient may not affect them but may be completely debilitating in another animal.
  5. Desiccated and disarticulated bones do not include soft tissues and are not innervated. Comments about soft tissue pain and inflammation or joint instability are difficult to support, unless there are overt signs of chronic osteoarthropathy (See #1 above).
  6. Gross dissection reflects a single point in time. The soft tissue and boney changes visualized typically reflect only what is present at the time of death.
    • Perceived lesions may not reflect what was going on in the horse’s body last month, 1 year ago, or 5 years ago, unless there is well documented evidence of a chronic disease process based on serial physical exams, blood work, or diagnostic imaging.
    • Radiographs or CT imaging can reveal evidence of prior bone or joint injuries that are not readily apparent on gross evaluation. However, most soft tissue and bone injuries heal and will show no evidence of having ever occurred.
    • Clinical signs may wax and wane. While there may be gross evidence of soft tissue fibrosis or an enthesopathy, it does not have to be associated with any clinical signs at this specific point in time. While there were likely clinical signs of pain and inflammation at the initial stages of onset, which could have persisted for some indeterminate period, it does not mean that the clinical signs had to last for the entirety of the horse’s life.
  7. Gross dissection may not always include histologic assessment, which is needed to document microscopic changes required to confirm a diagnosis of nerve or spinal cord compression, collagen defect, cartilage damage, or muscle disease.
  8. Gross dissection does not always allow clear visualization of bone surfaces unless the bones have been carefully disarticulated and all soft tissues removed.
  9. Anatomical variations and asymmetries are commonly observed. The clinical significance of any anomaly depends on the structures involved, location, severity, extent, associated clinical signs (if any), and concurrent disease processes (e.g., osteoarthritis).

Acting responsibly and ethically

I am a life-long learner and fully support those who aspire to do the same.

While anatomy is defined as the study of structure of organisms, we often assign functional characteristics to the named features (e.g., elbow flexor). However, critical errors in judgment are made when clinical signs are attributed to anatomical variants or pathologic changes in the absence of any accompanying medical history or physical examination findings.

We need to always be mindful that if we are going to post dissection photos on social media, then the material must be presented in a professional and ethical manner, structures must be clearly and accurately labeled, and any commentary on clinical relevance must be strictly limited unless clearly supported by ante-mortem findings.

There is so much to learn – we do not need to be confused or misinformed by unintentional exposure to inaccurate or misleading information.

Have you attended a properly organized dissection? What are your thoughts about who should be dissecting and sharing dissection information?

January blog topic: Recognizing Red Flags

Next (free) online Community Gathering on this topic: January 31, 2024

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