Most zoological facilities do not have the luxury of having a full-time staff pathologist. In most instances the staff veterinarian functions as the on-site pathologist, performing necropsies, collecting postmortem diagnostic samples, and assigning gross pathologic diagnoses. Staff veterinarians are also frequently called upon to design necropsy facilities for their institutions. Necropsy facilities should generally be simple in design (Figure 1) but should take into account several important concepts.
Isolation is ideal but separation is acceptable. Ideally, a necropsy facility should be designed and built as a standalone building isolated from all live animal functions of the institution. If the necropsy facility must be attached to a hospital or other facility, it should be functionally separated using an anteroom system or outdoor access only. Attached necropsy facilities should have separate air handling systems to prevent air exchange with other portions of the building. Local, state, and federal regulations may require special treatment of waste water before it is discharged into municipal sewer systems or specially-designed septic systems for non-municipal waste water handling. It is very helpful to seek assistance from an engineer experienced in designing air and waste water handling systems for other biocontainment facilities (e.g., morgues, lab animal facilities, etc.). The necropsy building should be designed to be self-sufficient with its own laundry, rest room, equipment cleaning, specimen preparation and storage, and janitorial facilities to prevent movement of fomites. A changing room with lockers, boot rack, and shower is useful for changing before and after the necropsy and to prevent contamination of work clothes and shoes. The design should also provide for local containment of wastes within the facility using depressed floor spaces, flanged tables with drains, and convenient equipment storage and flow patterns to reduce tracking. Foot baths are helpful at entry and exit points to prevent tracking of infectious agents out the necropsy facility. Continuous decontamination can be designed into the facility using UV light systems that turn on when the building is shut down and floor resins with built in antimicrobial substances.
Besides biosecurity considerations, the site chosen for a necropsy facility should be easily accessible for trucks carrying large carcasses to the facility and for waste disposal trucks carrying away postmortem wastes. The design should consider a large door for backing trucks directly into the facility for ease of carcass drop off and waste removal.
Ease of Use
A necropsy facility should be designed to facilitate the postmortem procedure from start to finish. The facility should allow the clinician to perform necropsies in an efficient and comfortable manner to prevent procrastination, improve accuracy, and prevent fatigue. Starting with the delivery of the carcass, a winch and rail system makes removal of large carcasses from a truck and movement of carcasses simple and labor saving. The rail system should be designed to easily take a carcass anywhere you may want it (e.g., cooler, postmortem table, floor) and should be engineered to handle the largest carcass you would bring into the facility. A scale can be hung from the winch for weighing large carcasses as they enter the facility or a built-in floor scale can be used to drive a truck on or to place the carcass on with the winch. The winch can also be used for necropsy of carcasses in a vertical presentation and for putting tension on and easily removing large objects such as extremities. The ceiling height of the facility should be high enough to accommodate the longest animal that would be hung from the rail system. A walk-in cooler should be included in the design to cool carcasses that cannot be examined immediately and for storing solid wastes until they can be removed. The cooler should be large enough to hold the largest carcass you may want to store and the door of the cooler should be designed to open and close easily by any member of the staff. A separate entrance near the necropsy cooler is useful for keepers dropping off small carcasses. A scale and log-in area near this door helps to make sure accurate postmortem weights and inventory information are collected during drop-off. The working floor space should be large enough to handle a very large carcass on the floor and small to large carcasses on a table. The working floor can be depressed from the surrounding floor for containment of fluids and wastes. The working floor should be heavily sloped to a large trench drain for ease of cleaning. The trench drain should be covered with a lightweight, epoxy grid to prevent large parts from entering the drain. A built in flushing system for the trench drain is useful for keeping it clean and flowing during a large necropsy. A large U-shaped stainless steel postmortem table is useful for the necropsy of a wide variety of animals. The table should have adjustable legs to prevent fatigue from stooping, flowing water and grooves or trenches to carry water and fluid underneath the animal to the drain, and a large trap drain with a strainer. This type of table can be manufactured by local stainless steel fabrication shops. A large, commercial, stainless steel dish rinsing spray head on a spring-arm is useful for rinsing and cleaning the table. A postmortem scale should be hung above or on the table for weighing organs. Stainless steel wings can be attached to the table for holding cutting boards and instruments. An electric outlet should be stubbed up on or near the table for electric supply to auxiliary lights and postmortem saws. A large two-sided stainless steel sink on legs with stainless steel wings is useful to have within the containment portion of the necropsy floor for cleaning, drying, and storing necropsy instruments. For facilities with many small animals, it is useful to have a small necropsy table that is set at an appropriate height and designed for performing necropsies sitting down. Accessory table lighting is essential when examining small specimens. A self-standing, adjustable, ring-lighted magnifying lens is helpful for dissecting small carcasses. A built in site with electricity on the table for a dissecting scope is extremely useful for examining and dissecting very small specimens where more magnification is needed. Good lighting is essential for all necropsies. Fluorescent ceiling lighting is relatively inexpensive and can be used effectively in necropsy facilities. Fixtures should be spaced close together (approx. 1' apart) over the main working areas to provide effective lighting. Fluorescent tubes that provide true color rendition of tissues are best to use. The light fixtures can be wired in zones, for energy efficiency, to allow all or individual zones to be turned on depending on what is being done in the room. Metal halide down-lighting provides very effective and true color lighting over work areas but is much more expensive and less energy efficient. Metal halide fixtures can be interspersed with fluorescent fixtures to provide more natural, bright light. Either permanent-mounted or moveable floor-mounted, focusing surgery lights are very helpful for visualization within deep body cavities and for delicate dissections. It is helpful to have a cordless phone in the necropsy facility so calls can be taken without leaving the containment area. A computer terminal in the necropsy facility will allow prosectors to review medical records. The addition of speech recognition software to the computer will, in the future, allow easy dictation of gross necropsy findings into a computer file format for insertion into necropsy records. Be sure to include your technician staff in the design phase of the necropsy facility since they are an integral part of the necropsy team.
The necropsy facility should be designed to prevent back injury and other injuries caused by lifting, over-exertion, and abnormal posture. A winch and rail system, as already discussed, will make lifting and moving of large carcasses and parts relatively easy and prevent many injuries. Waste tissues and parts can be placed in a plastic bin or trash can on wheels which can be moved without lifting. Tables should be adjustable for normal standing or sitting for a variety of animal sizes to prevent abnormal posture and fatigue. Large carcasses can be necropsied in a vertical position while being held by the winch to limit stooping and bending down. Cushioned rubber knee pads can be used for kneeling around a large carcass to work rather than bending over to work. The flooring should be slip-proof when wet to prevent falls. Depressed work areas in the floor should be marked with yellow lines for warnings to prevent falls. All electric outlets, switches, and light fixtures should be waterproof to prevent electric shock. The air handling system for the postmortem work area should be engineered similarly to one used for a laboratory animal facility. There should be at least 15 fresh air exchanges/hr and preferably more with HEPA filtration used to reduce airborne pathogens. Temperature should be easily controlled to keep the work space comfortable at all times of the year. The area used for formalin-fixed tissue handling and storage should be a separate room from other work areas and should have a separate air handling system to prevent formaldehyde gas from entering other work areas. The air handling system in this room should be engineered to prevent unacceptable ambient air levels of formaldehyde gas. A hood approved for use with formalin or a down-draft table should be installed in this room to store tissues which are fixing in formalin and for any manipulations of formalin or formalin-fixed tissues (e.g., pouring, formalin exchange, cutting and bagging tissues, etc.) to prevent unacceptable exposure. A biologic hood for performing necropsies on cases with suspected zoonotic diseases will help to contain and prevent aerosol exposure to infectious agents. A changing room with shower allows quick changing into and out of necropsy garments to reduce pathogen exposure and prevent fomite transmission.
Sample Preparation and Storage
It is useful to have at least two other rooms or work areas within the necropsy facility for photography and tissue/sample preparation and storage. One room would be used for formalin-fixed tissue preparation, cutting, and storage. This room would, as described above, have a separate air handling system and ventilation hood to reduce employee exposure to formaldehyde vapors. The hood should be lighted, should have a built-in sink with running water, and should be designed for someone to sit at for tissue cutting. An eyewash station should be present. A cabinet system for long-term storage (filing) of formalin fixed wet tissues is most useful. The drawers should be lined with impermeable plastic liners to hold formalin in case of leaks. A separate smaller cabinet can be set up for long-term filing of paraffin tissue blocks. The second room or area should be open to the main necropsy floor and would be used for unfixed tissue/sample handling, preparation, and storage. This room should have a large table for packaging tissues/samples, cabinets, drawers and shelves for general storage, and counter space for microscopes, etc. Conventional and ultra-low freezers could be kept here for sample storage. A corner of this room can be designed for photography of postmortem lesions with camera stand, above and below lighting, etc. A computer station in this room is useful for examining medical records and for typing or dictating pathology reports.
Ease of Cleaning
The pathology facility should be designed with ease of cleaning and disinfection in mind. Depressed floor spaces keep fluids and other wastes within a confined space for easy clean up. Troweled epoxy floors are seamless and impervious. They can be coved up the walls to have smooth seamless transition from floors to walls for ease of cleaning and disinfection. Walls can be painted with epoxy-based paints or covered with other smooth, impervious materials to allow easy cleaning. Floors should be heavily sloped (at least 1 inch/foot) toward drains to allow easy cleaning and rapid drying after hosing. Trench drains work well in large work areas. Built-in flushing systems within trench drains are very useful. Smaller areas should have large round drains with removable baskets. The floor of the walk-in cooler should have a large central drain with floors sloped heavily toward the drain. Commercial hose reels for cleaning can be mounted high and out of the way. Hoses should be long enough to reach anywhere in the work area and should be supplied with both hot and cold water. Good water pressure is essential. A proportioner can be added to the hose assembly to apply disinfectants easily to the floors and walls. Necropsy tables should have sloped surfaces and drains should have straining baskets for removal of tissues and debris or heavy duty electric disposals to grind waste for delivery to the waste water system.
Click on the image to see a larger view.
|Figure 1.White Oak Conservation Center necropsy facility floor plan.|
Thanks to Richard Montali, DVM for contributing useful suggestions to this manuscript.