Le rôle du vétérinaire dans le traitement des cas de cruauté envers les animaux - Merck
(Ce texte est disponible en anglais)
Veterinary Forensics : Making the Case - Proving Cruelty Through Forensics
Melinda D. Merck, D.V.M.
Vice President of Veterinary and Forensic Affairs
Georgia Legal Professionals for Animals
Roswell, Georgia U.S.A.
Making the case for animal cruelty requires a perfect investigation from the beginning by all parties involved. The same mistakes we see in high profile murder cases will cripple these cases as well. The burden of proof that must be met for crimes against humans applies equally to crimes against animals. In animal cruelty cases this standard is even harder to meet because there are usually no witnesses and the victim cannot speak. The veterinarian's role is crucial - we will be testifying for the victim.
Veterinary forensics is a new and emerging field. Veterinarians by nature are already skilled investigators. For each medical "puzzle" we investigate we collect clues and employ the power of deductive reasoning to arrive at a solution. The field of forensic medicine requires an adjustment to your normal way of thinking to expand the list of possible solutions to include the horrific. To enter this field you have to consider the dark side of human nature and think "outside the box". You can no longer afford to turn a blind eye - for the sake of both the animal and society.
CSI - Crime Scene Investigation
Investigation of the crime scene covers many different areas in which the veterinarian is either directly or indirectly involved. Information about the crime may be gathered by the investigator and/or the veterinarian. The sources of information include the first officer on the scene, witnesses, neighbors, landlord, the owner, friends, and your staff. It is important the veterinarian get as much information as possible from all sources. Try to have a witness either in the room or in the adjoining room when you are questioning someone. Remember, any statement given to you may be hearsay and not admissible in court. There are exceptions but ultimately a detective should question the parties involved.
The environment must be investigated either by an investigator or crime scene unit with or without a veterinarian present. Regardless of the type of cruelty, pictures should be taken of the environment. You should receive a copy to analyze along with your physical exam findings. Based on the photos you may require the investigator to return to the scene and look for additional evidence or the photos may be inadequate and need to be re-taken.
The animal in and of itself is a crime scene and should be treated as such. Your examination should be methodical and complete in all cases. You should develop a systematic approach that ensures all parts of the body and systems are covered, noting those that are normal and abnormal. If you fail to note normal findings it can imply the examination was incomplete or something important was left out. A good defense attorney will use this to raise reasonable doubt by suggesting your exam was inadequate or that potentially exonerating evidence was intentionally omitted.
Collecting items and samples for testing is part of the veterinary forensic investigation. The results of the tests will either support your initial conclusion or steer you in a different direction. They may also provide you with additional evidence of injury not seen in your initial exam.
As you gather data from all parts of the investigation you may need to go back and revisit a particular area. You may need the environment re-examined or further testing may need to be performed. It is critical that the initial investigation be done as quickly as possible in order to preserve this option. The integrity of the evidence may be compromised with time.
Chain of Custody
Any evidence related to a crime must follow a chain of custody. This refers to a recording process where the evidence is accounted for at all times. "Evidence" is anything collected at the scene of the crime, from the animal, all samples, all photographs taken, the photo card or negatives and the animal itself. In all cases of suspected cruelty it should be the police or animal control that transports the body to the veterinarian. All evidence must be labeled with date and time, a description of the item and the person who collected it should initial or sign across the seal. An evidence log must be maintained showing the same information and the location where the item is kept. All evidence should be kept in a locked cabinet with restricted access. If the evidence is transferred to another person, location or laboratory, this must be noted with time and date and a signature required. This applies to the body of the animal as well. Human labs already have a system in place to record chain of custody when dealing with criminal cases. But most veterinary facilities do not. When sending a sample you need to record in detail the samples submitted, how it is packaged, by whom, the date and time, the carrier, and the case number. On the testing request form you must note and highlight that this is a criminal investigation. Send a "Cruelty Case Samples Receipt" form for the lab to fill out. This should be faxed back immediately to you on the day the sample is received. This is crucial for the test results to be admissible and to stand up to scrutiny in court.
It is important to have the proper tools to conduct your exam and collect evidence. Do not place evidence in plastic bags because moisture can compromise the integrity of the sample. If an item is wet you may first place it in a plastic bag for transport up to a maximum of 2 hours. Then take the item out to dry before finally placing it in a paper evidence bag.
|Examination and Collection Tools
Trace Evidence Tape
There are some positive and negative attributes of an animal's body and behavior for retention and retrieval of trace evidence versus a human's. Persistence of trace evidence is affected by the size and texture of the material being transferred, the surface on which it is retained and how easily it is removed. The fur can hold imbedded trace just as human hair and you have an entire body to which it could stick. But depending on the density and length of the fur the trace may be more easily dislodged and lost. The human nail has a pocket under which trace evidence may become trapped. In animals this is less likely unless the nail is frayed and the evidence is caught in there or on the fur between the toes and pads of the feet. Other sources of trace evidence may be collars and leashes.
The persistence of trace evidence is also affected by the length of time since the offense was committed and the activity of the suspect or victim. The behavior of an animal after it is injured or frightened is to lick their fur or the injured area removing valuable evidence. They may also rub or roll around and they often tend to run and hide. To preserve trace evidence an animal's body should be wrapped in a white sheet and the feet sealed in paper bags prior to transport. These items should be saved as evidence.
|Types of Trace Evidence
When examining for trace evidence use a UV light source and an indirect light source (held at an angle) such as a flashlight. Always photograph trace evidence prior to collection. The physical context may be paramount to the value of the results. You should take a control sample of the animal's fur with the root intact including one of each color. Place each item collected in a separate paper envelope. If the item is collected with tape then place it in a box lined with wax paper. There are special "tape lifters" that come with their own wax coated collection paper. Accelerants evaporate and are flammable. These samples should be placed in an airtight non-porous container such as a non-coated paint can or glass jar.
When looking for deeply imbedded trace evidence, place white roll paper on a table and tape it in place. Place the animal on the paper and comb the fur, one section at a time, using a fine tooth comb. Use your light sources to examine the debris. Collect anything obvious and save the remaining debris in a paper envelope. This combing can also help you detect wounds and areas of tenderness.
Initial Physical Exam
Before beginning your exam take precautions to avoid contamination of evidence by wearing cap, mask, gown and gloves. Record the body weight and body score. Take pictures throughout the exam getting distant, mid-range and close-up views. Note the mental status and overall health of the animal. The behavior of an animal can be revealing. Look for extreme fear reactions such as defecation, urination, head shyness and fear of a specific type of person or what they are wearing. Examine the coat with a UV light for trace evidence, saliva (animal attack), blood (their own, another animal or human) and other bodily fluids. When taking samples also take control swabs adjacent to the area of interest. Examine for other evidence of injury. Photograph all injuries before and after shaving or treatment. Remember, the animal is part of the crime scene. Do not ruin evidence with treatment if at all possible.
Patterns of Non-Accidental Injury
Determining accidental vs. non-accidental injury begins with an index of suspicion when the exam findings are not supportive of the initial history. It can be due to abnormal behavior from the owner such as nervousness or apathy, or if their account of the accident continually changes. Whenever something tips you off that things are not adding up then you have to investigate further. It is imperative that you are thorough and document meticulously.
All cases of suspected cruelty should have full body radiographs starting at the head of the animal. This applies to live as well as deceased animals. Radiographs will reveal occult injuries such as diaphragmatic hernias, lung contusions and fractures. Also look for dated injuries such as healing rib fractures. Save all radiographs as evidence.
The feet contain clues vital to your investigation. Not only can they hold trace evidence but their injuries (or lack thereof) tell a story. When a body is tossed at a high velocity the feet sustain frayed or ripped toenails and torn pads. Frayed nails can also result from an animal frantically moving its feet such as escaping up a tree.
The feet should be examined for trace evidence caught in the nails or between the pads such as blood, hair, fibers and glass. The nails should be individually scraped over paper, doing each foot separately, placed in an envelope and saved for DNA and trace analysis. If the animal is deceased it is better to remove the entire nail.
When examining the head look for asymmetry from contusions or fractures. Palpate for fractures and take radiographs. Examine the internal ears for petechiae, fresh hemorrhage and ruptured tympanic membranes. Check the mouth for fractured teeth, torn palates, tongue lacerations and foreign material. Save any blood or material found. Examine the eyes, including the fundus, for bleeding, cloudiness, and luxated lenses. Internal cranial exams are probably best performed by a university necropsy service. Inform them it is a cruelty investigation and request photo documentation.
An animal that has died from heat stoke has a characteristic posture of stiffened legs resembling rigor mortis. Intense heat causes muscle proteins to coagulate which in turn causes muscle shortening. This is different than rigor which is a transient condition. Visceral congestion and petechial hemorrhages may also be seen.
Abrasions and Bruising
Abrasions need to be examined for patterns that can match a potential weapon. Take quality photographs that a forensic weapon specialist could use to make a match, making sure to include a ruler in each shot. Examine abrasions for imbedded debris such as glass or gravel. This can be supportive evidence that the animal was dragged or tossed and the debris itself is evidence of the scene of injury. Glass can often be matched to its source such as headlamps. Note the location, size and shape of the abrasions - together they tell the story. What you assume is a simple HBC may be cruelty therefore your analysis must be complete.
External bruising is less common in animals because the skin in animals is thicker, has fewer blood vessels and the fur coat protects it. The presence of skin bruising, with or without a fracture, is usually the result of severe blunt force trauma. Bruising can also take hours to form so close monitoring is essential. Most bruising and skin trauma is seen in the subcutaneous tissue, musculature, or body walls. On post mortem exam it is best to dissect and reflect the skin and inspect the underlying tissue. Bruising around the time of death will show little to no inflammatory reaction on microscopic inspection.
Burn wounds present in a variety of ways but they always tell a story - it is up to us to decipher the clues. Examine and photograph the burn patterns. Always smell the burns for clues to the cause such as accelerants, oil or chemicals. Swab the wounds and surrounding hair for analysis of the offending agent prior to treatment. Microwave burns can cause the thinner peripheral tissue to burn and deep internal organ damage depending on the length of time exposed.
There are seven main objectives when analyzing gunshot wounds:
- Determining entrance and exit wounds
- Retrieving gunshot residue
- Retrieving the projectile
- Retrieving any bullet cartridge or casing
- Determining trajectory
- Determining gunshot range
- Recording injuries
There are some basic rules for determining entrance and exit wounds. In animals we have the advantage of fur being forced in or out, respectively. In general, entrance wounds are smoother and smaller than exit. Entrance wounds may have singed fur or skin indicating direction of travel. Abrasion rings may be found at entrance wounds where the bullet rubs raw the edges of the hole. The ring may be concentric or eccentric if the bullet entered at an angle causing a "bunching up" of skin. Entrance wounds may also have micro-tears at the edges if caused by a high velocity gun. If the bullet entrance is at an area of thick skin or it is a distant gunshot to the head the wound will usually have a stellar appearance. Contact gunshots produce splintered or star-shaped wounds because the bullet has a degree of wobble when first exiting the barrel of the gun.
Check for gunshot residue, known as GSR, on the body, nearby objects and blown inside the wound. GSR can be accurately identified at a lab using a dissecting microscope. Samples may be collected using a cotton tip applicator moistened with isopropyl alcohol or 5% nitric acid. If you need to clean the wound to examine, first spray with hot water or hydrogen peroxide and let it sit to dissolve and remove blood.
In humans you may see "powder tattooing" of the skin. These are punctate abrasions producing a form of stippling due to gunpowder grains. This may or may not occur in animals due to their fur covering. Insect feeding can resemble wounds. Follow the tract - insects usually only penetrate the subcutaneous tissue.
Exit wounds are usually larger and more irregular. They can be stellar, slit-like circular, crescent or completely irregular. "Shored" exit wounds have abraded margins because the skin was next to something firm when the bullet exited causing abrasions. Exit wounds through tight skin such as the head tend to be larger. Those through loose skin can be small and slit-like.
When retrieving projectiles, care should be taken not to cause damage that will interfere with the rifling marks on the surface of the bullet. These marks can be matched to the gun it was fired from. Use your fingers or cotton wrapped forceps to grab the bullet. In shot gun injuries get a representative sample of the projectiles and any wadding if present. Place items in a paper envelope and then a small box for protection. Ejected cartridges and casing may contain fingerprints. Exercise caution not to compromise their integrity during collection.
All animals with gunshot injuries should have full body radiographs. An exit wound does not necessarily mean the bullet exited. The bullet could have propelled bone fragments and tissue out then rebounded back. Bullet emboli are possible.
Trajectory of the missile can help determine where the shot was fired from and helps re-create the crime scene. When probing the track use a metal rod being careful not to dislodge the bullet or create false tracks. A bullet path creates shearing, compression and stretching causing injuries distant from the path. This can cause fractures without a direct hit, usually rib fractures. With direct hits look for the bone beveling out and sometimes you can see lead deposit on the bone. Consider the animal may have been in motion and move limbs accordingly to match trajectory lines.
There are four categories of gunshot wounds determined by range of muzzle to target:
Contact Wounds: defined by a tight zone of soot and searing from hot gases and flame emitted from the barrel.
Near-Contact Wounds: the zone of searing is wider.
Intermediate Wounds: When the gun is fired from further away but close enough to produce powder tattooing (on the skin of humans).
Distant Wounds: characterized by only the mark of the bullet perforation.
Photograph each bullet wound before and after cleaning the wounds taking long range and close up views. Assign a number to each entrance wound and describe the location with a measurement to a landmark such as nipple, midline and the animal's muzzle. Describe the appearance of the wound, path of the missile, injuries produced and exit or lodgment site. Save any powder grains and describe such as flake, ball or cylindrical. Shave and note powder tattoo patterns, abrasion rings and muzzle imprints. When taking measurements you can use a clock reference identifying the dorsal spine or head as 12 o'clock. Record the injuries created by the missile path.
The wounds you may see can be stabbings, lacerations or skinning. Stab wounds made with a single edge blade create a slit that tapers to one end. If the knife is withdrawn partially and another stab made it will look like a fish tail with a double taper at the end. A double edge knife will have a taper at each end. The more dull or blunt the instrument the more ragged the edges and the more tissue bruising. It can be difficult to determine if the blade was smooth or serrated unless superficial wounds are present.
The track of the stab wound should be probed with a metal rod and measured. The width of the blade cannot necessarily be determined unless there is evidence there was full penetration such as bruising around the wound caused by the knife handle. You can also make a reasonable deduction if you have multiple stab wounds of various depths that all measure the same width. Record the injuries the same as you do with gunshot wounds.
It is important to note that in human knife stabbings the perpetrator's hand can slip cutting himself. So take samples of any blood found for analysis.
Blood Stain Analysis
A specialist should analyze photos of blood spatter. Photographs should include a ruler and yard stick to show the height of the blood stain and its relation to nearby objects at the scene. If at the scene you should draw a diagram. Always take multiple samples of the blood - it could be animal or human.
There are three main categories of blood stains:
Passive: drops formed by the force of gravity alone.
Transfer: formed when something comes into contact with blood and transfers it onto another surface.
Projected: created when an exposed blood source is subjected to a force greater than the force of gravity, either internally or externally produced.
There are certain things you might be able to deduce yourself such as drag marks, smears or blood trails. There are some generalities: when a drop of blood falls to a smooth floor it will remain basically spherical. If it is a rough surface it will be star-shaped, though drops from great heights will also be star-shaped. If blood strikes the wall at a right angle it will be round. At other angles it will be elongated, the more narrow part indicating the direction of travel. It may also splash smaller stains in the opposite direction from which the drop originated from.
Keep in mind an injured animal may be mobile and may shake his head or body causing spatter. Sneezed blood may be diluted or have air vacuoles. Insects may move through blood creating a false blood trail. Note that there are bleeding differences between species of animals - cats do not bleed from their skin like dogs do.
Blood Loss Calculation
The amount of blood lost by an animal is an important measurement for a criminal investigation. This can be calculated using the animal's hematocrit (Hct) or from the environment.
- In acute blood loss the body will draw fluid into the blood vessels over time to maintain pressure. Depending on the time elapsed or the administration of resuscitative fluids the Hct will be accurate. If the Total Protein is normal then not enough time may have elapsed for the body to respond. Normal blood volume for small animals is 90ml/kg.
(Lowest Normal Standard Hct - Current Hct) = Fractional Blood Loss
Lowest Normal Standard Hct
Fractional Blood Loss x Animal's Normal Blood Volume = Volume Lost
- If the blood has soaked into an absorbent surface the item may be weighed and compared to a clean control. The difference will give you volume. A liter = 1 kg. So a weight difference between two identical pieces of carpet, one blood soaked, of 0.4kg = 400mls of blood loss.
Animal DNA Forensic Testing
There are three categories of animal DNA evidence: as the victim, the perpetrator or the witness. Sources of DNA include blood, saliva, urine, feces, hair, semen, bones, teeth, organ tissue, muscle and skin. DNA may be obtained from toys, bedding, brushes, bowls or related property to help identify a particular animal. During the commission of crime animal DNA can be transferred directly or indirectly from an animal to the crime scene or onto another person.
When examining a case of cruelty you need to consider what DNA from the human may have been transferred to the animal. The animal may have bitten or scratched the offender in the struggle thereby retaining human DNA on the teeth or nails. Or the offender may have bled on the animal. You have to consider everything possible and look for it in your initial exam or your evidence may be lost.
Proper sampling technique is paramount for successful DNA determination and the key to the results standing up to scrutiny in court. Strict chain of custody must be followed. It is preferred for the original item to be submitted. Otherwise the item should be swabbed avoiding contamination. Control samples are also needed. See the websites for guidelines.
If an animal is alert and stable DO NOT immediately remove the foreign object. Doing so may cause severe damage. The foreign body may be applying pressure to vital blood vessels preventing hemorrhage. Plan surgically how to extract the object. Take precautions to preserve fingerprints and the integrity of the object for evidence.
Ligatures cause crushing injury to the skin, the blood vessels and the tissue underneath. In addition the surrounding tissue swells due to inflammation, infection, and compromised blood supply and vessel drainage. The various types of ligatures may be used such as rubber bands, wire or rope. Look for tell-tale patterns on the wound or abrasion if the type of ligature is unknown. Inspect the area for trace evidence related to the ligature.
A death by asphyxia requires careful examination of the neck. You should inspect the entire trachea, larynx, tongue, submandibular lymph nodes and the surrounding tissue for evidence of injury. Careful neck dissection must be performed layer by layer. Remove the tongue and neck structures all together by cutting below and inside the entire mandible to free the oral tissues. Petechial hemorrhages may be seen in the conjunctiva, sclera, oral mucosa, soft palate and periorbital tissues. The presence of such hemorrhages is not diagnostics for asphyxia- in humans it is seen with seizures and SIDS. And the lack of hemorrhage does not rule out asphyxia as the cause of death. Animals have thicker neck and chest muscles providing more protection. Fractures of the hyoid bone may be found, depending on where the compression occurred.
Categories of Asphyxiation
- Smothering: look for material in or on the mouth, facial injuries and torn frenulums.
- Choking: look for a foreign body and aspirated foreign material.
- Airway Swelling/Obstruction: look for evidence of an allergic reaction, infection, irritants, mass and swelling. A blow to the neck can take minutes to hours to swell and occlude the airway.
- Neck Compression: caused by the constriction of the jugular and carotid vessels with or without airway compression.
- Manual Strangulation: defined by the use of hands. Shave and look for round oval contusions and possibly fingernail marks. Examine the neck layers after chest contents are removed to minimize hemorrhage artifact. Look for hemorrhage within the muscle of the tongue by making multiple crosswise slices.
- Garroting (Ligature): ligature marks are usually horizontal with possible multiple marks as the perpetrator was trying to get a purchase. Inspect the area for trace evidence.
- Yoking: compression of the anterior neck usually with a forearm or object causing internal neck damage.
- Compression of Chest/Abdomen: this causes an increase in intrathoracic pressure and hinders breathing. In addition to facial petechiae it may be seen on the neck, shoulders and chest. You may see small hemorrhages in the neck and chest muscle attachments. Look for marks on the torso, rib fractures and organ damage.
- Hanging: look for an impression pattern of the ligature and an inverted V-shaped bruising on the neck. Know the position of the body before it is cut down and save the knot of the ligature. If the hanging involved a drop prior to suspension you may see separation of the cervical vertebrae. There may be areas that look like hemorrhage on the lower body due to the pooling of blood. This can cause blood vessels to break due to the increased pressure. This post mortem pseudo hemorrhage is known as Tardieu Spots.
Death by drowning can be difficult to diagnose. It is usually diagnosed by excluding all other causes of death coupled with supporting circumstances surrounding the death. Wet lung drowning is caused by water aspiration and dry lung drowning is caused by laryngospasm. The water environment affects rigor and decomposition based on the water temperature and bacteria present. Decomposition is generally slower than in air but accelerates when out of water so perform the necropsy as soon as possible.
You need to determine if the animal died before or after it was in the water which is difficult. Look for signs of ante mortem injury though they can mimic post mortem if any hemorrhage is leaked out by the water. Petechiae if present are usually on the pleura of the lungs.
The most specific indicator is foam from the nose or mouth, either white, off white or pink, caused by the admixing of moving air with water. It will continue to form if wiped away. This foam may be found in the trachea or distal airways. It can also be seen with pulmonary edema. The absence of foam does not rule out drowning.
Other non-specific findings are heavy lungs and hyper-inflated lungs. Water, plant material and silt in airways or stomach are not diagnostic because they can enter passively. However, these findings in a body not found in water should raise you index of suspicion. Save water and any debris for testing and to help identify the death scene.
Any substance in high enough quantities can be toxic. The environment can hold the key to identifying the poison. Always ask what food the owner normally feeds, when the animal last ate and compare to vomit or gastric contents. Proper sampling and submission is critical. If the toxin is known your lab can tell you what specific samples to submit. If it is unknown, in addition to unfixed tissue samples, you must include fixed tissues for histopathology. Each specimen should be in a separate labeled container, wrapped in foil and placed in a Ziploc bag. Do not mix samples together.
Toxicology samples (unfixed): Check with your lab regarding quantities. Stomach contents, vomitus, intestinal contents, liver, kidney, brain, urine (frozen), refrigerated blood (EDTA, serum or plasma), 3" x 8" section of skin for pesticide testing, water, soil and forage.
Histopathology samples (fixed): Heart, liver, lung, spleen, kidney, brain, and lesions.
In these cases you need to inspect the perineal area for evidence of trauma. Look for painful defecation, rectal or vaginal bleeding or abrasions. Use a UV light source to examine the fur and perineal area for bodily fluids and take samples. If the fluid is dried, moisten a cotton-tip applicator with distilled water and swab the area. Always take an additional control sample adjacent to the area of interest. Perform a vaginal exam to check the mucosa and cervical area for bruising or trauma. Take sterile swabs of the vaginal area for semen and STD's. You can make a separate slide and examine the swab sample for sperm. In addition swab the gums, teeth and mouth area for possible DNA. Take multiple rectal swabs to test for semen and blood prior to taking the animal's temperature. Fecal contamination does not matter because they will be testing for DNA. If blood is found on a rectal swab or the animal exhibits painful defecation colonoscopy may be indicated.
Neglect comes in many forms: starvation, lack of proper care and filthy living conditions. Your reports of neglect cases should always include a time estimate for the injury or condition to have been present to address the degree of suffering. In neglectful behavior, which is the failure to act, the issue becomes at what point the person had knowledge and therefore malice.
Always start with photos. Record body score, weight and perform lab work. On post mortem exam you need to note the loss of external and internal fat. The pericardial and perirenal fat is some of the last to be lost. Bone marrow fat is the last to be lost. A bone marrow fat analysis can be done post mortem at Michigan State University. Normal range is 50-60% and in starvation cases it can be as low as 0-10% though a normal value does not rule out starvation. This fat can become rancid with time but freezing will preserve the fat for up to a year. Look for evidence of pica in the feces and stomach contents. Check for gastric ulcers, occult fecal blood and melena.
You must document the physical condition of the animal. You need to see photos of the environment. In your report you need to address the physical and mental stress, the medical and behavioral effects on the animals living in such an environment. Most collectors do not spay and neuter. When there is a large number of intact animals living together in a confined space you may see forced mating and genital trauma.
You must note in your report that this injury takes several weeks to months to occur. Note the foul odor and all visible signs of trauma that the owner must have seen and smelled. Pictures should be taken before and after shaving and treatment. The width and depth of the wound should be measured. Save the collar.
Dogs used for fighting are usually suffering from starvation, untreated injuries and have been beaten. Signs to look for are heavy chains used as collars, scars on the face, ears, neck and legs. Close ear crops are not always present. These dogs should be tested for speed, steroids, hormones, diuretics and analgesics.
Time of Death (TOD)
Establishing TOD is not an exact science. There are guidelines extrapolated from our human counterparts but more research is needed. In order to determine TOD we have to figure out the Post Mortem Interval. It is imperative that environmental conditions are recorded whenever a dead body is found as well as the condition of the body.
Liver mortis: This refers to the discoloration of the body due to gravitational blood settling after the heart stops. Lividity is not often seen in the external skin of dogs and cats. It is more likely to be seen on the buccal mucosa, internal organs and body walls. This can help determine the position of the body after death.
Algor mortis: This refers to the body cooling. It is more accurate in the first 24 hours after death. It can be affected by temperature prior to death, size of the body, dehydration, obesity, edema, body position (curled vs. recumbent), hair coat, humidity, wind, cover and water immersion. When taking the temperature a special thermometer is needed to register low temperatures. Readings may be taken rectally or in the liver. You can make a small cut in the skin and insert the thermometer into the liver or under a lobe to avoid damage. There is an initial temperature plateau that occurs in the first 30 minutes to 5 hours. The normal rate of cooling is 1.5 degrees Fahrenheit loss/hr (rectal) at 75 degree environmental temperature. Take two reading in an hour to get the rate of cooling and confirm you are past the plateau.
Rigor mortis: This refers to a stiffening of the muscles and freezing of the joints. It involves the formation of locking chemical bridges of the muscle proteins actin and myosin. When an animal dies the muscles are initially flaccid, then stiffen (rigor) then they become flaccid again. The onset is faster and duration is shorter in animals that have decreased glycogen levels seen with starvation, exhaustion, seizures and sepsis and in high environmental temperatures. Rigor sets first in the smaller muscle groups and joints, usually the head, and then moves to the larger muscles. It then dissipates in the same order. Rigor can be forcibly broken with manipulation and will not recur unless it is broken before full development. It is important to ask how the body was handled prior to you receiving it.
|Time of Death Estimates in Animals (Dr. Annette Rauch, Tufts University)
|Warm, not stiff
||Cold, not stiff
Gastric Emptying Time: Gastric contents and emptying times are helpful in human medicine in determining time of death. In an animal where it is known what and when he last ate you may be able to use that information. It is affected by many factors: solid or liquid food, caloric content, water intake, volume, and whether fed meals or free choice. It can be affected by the age and size of the animal. Keep in mind that we need to look at the maximum time so we can establish a minimal post mortem interval and place it in context with other post mortem findings.
||Solids 4.7-15 hours
||Liquid 0.5-3.5 hours
||Solids 4.7-12.5 hours
||Liquid 1 hour
|Average Normal: < 14 hours
Entomology: Maggots can aid in determining TOD, location of death and provide DNA and toxicology evidence. The larvae grow and molt at a certain rate, depending on the species and environmental conditions, and can be aged by an entomologist. Live samples of the largest instar larvae need to be preserved on a piece of beef liver. They also need detailed environmental reports for the previous 2-3 wks of where the body was recovered. If the body was stored prior to examination the time and temperature must be recorded. If possible live flies should be caught at the death scene. Preserve additional maggots by placing a sample in boiling water and freezing another. Maggots can identify sites of trauma on the body since they only gain entrance through an orifice or wound. Different kinds of beetles feed at different times post mortem. A sample of all insects on the body should be obtained. With these and weather data a forensic entomologist can help determine TOD. Contact the entomologist for sample submission guidelines.
Report of Exam Findings
Your report should be professional, logically structured and complete. Based on this report the DA's office will decide whether or not and how to prosecute. You may be asked for a preliminary report - this should only contain confirmed findings and pending tests. You cannot retract what is in there later on without a valid reason. In this report you must address the survival period: the time from injury to death. This speaks to the animal's suffering and is important for the prosecution. It can make the difference between misdemeanor and felony charges.
Heading: Include name of investigator and the unit, your name, address, contact info, date of exam
Subject of Exam: Accurately describe the animal - color, sex, intact, age
Reason for Exam: Why the animal was brought to you
Examination Findings: Details of findings, group injuries under "Evidence of Injury"
Procedures: List all procedures, samples taken, test results or pending
Summary of Findings: List all pertinent findings
Crime Scene/Forensic Information: List what you personally observed at the scene or from photos, what the investigator told you and any forensic test results
Death/Injury Statement: List survival period, cause of death, manner of death
Manner of Death Categories for Animals
Where you state your opinion of all the evidence. You may use lay terms for the investigator and prosecutor to understand.
During the entire investigation it is important for you to communicate with the investigator and the prosecutor. They may have information for you and they certainly need any information you have. It is a very important role that veterinarians play in every animal cruelty investigation. Everyone involved needs to know that we will step up and become a part of the process that ensures justice for the animals we swore an oath to protect.
References, suggested reading, websites and COC forms @ veterinaryforensics.com
Address (URL): http://www.vin.com/Members/CE/C232/Library/CE_M05976.htm