CARCASS DISPOSAL OF ANIMALS
Deepak Kumar1, Sanjay Kumar2 and Savita Kumari3
1 Assistant Professor, Department of Veterinary Pathology, Bihar Veterinary College, Patna
2 Assistant Professor, Department of Animal Nutrition, Bihar Veterinary College, Patna
3 Assistant Professor, Department of Veterinary Microbiology, Bihar Veterinary College, Patna
The disposal of carcass and disinfection of the site as well as of the persons involved in handling the carcass during necropsy examination is one of the most important job after postmortem and collection of morbid materials for laboratory investigations are over. Every bit of the carcass and the disposals used by the handlers should ideally be incinerated at a very high temperature (850-1050˚C) without releasing any suspended particles in the atmosphere. The floor of the PM house should be cleaned with hot water and detergent. The wash should go to the effluent treatment plant where it is chemically treated, oxidized and filtered before releasing to the drainage system. Conversely the wash should be disinfected by directing to a boiler and heated at a sufficiently high temperature and treated with bleaching powder or potassium permanganate solution. In field condition, the disposal of carcass is done by different methods, i.e -Burial method, Burning or incineration methods and Chemical treatment. Burial method this is the most common method and is fairly safe if the burial pit is dug 2-meter-deep or highest part of the carcass is at least 1.5 meter below the level of surrounding terrain. Besides the carcass, left over feed by the dead animal, its bedding, excreta and top 5 cm soil floor are also buried with the carcass. Deep burial will prevent the jackals from digging up the carcass and insects from carrying the bacterial spores to the surface. Once the carcass is in grave, the skin is slashed and drenched with crude phenol. Then the carcass is covered on all sides with quick lime and filled with mud and topped with some concrete objects. In case of anthrax, before removing the carcass for disposal, all its orifices are plugged with cotton soaked in 5% cresol and body is wrapped in similarly soaked bag. The byre should be disinfected with 5% cresol using long handled brushes and then washed over with freshly chlorinated lime-wash. Burning or incineration methods can effectively destroy carcasses. It can be conveniently done in incinerator where a temperature of 600-800C is reached and all the organisms are destroyed. This method is quite suitable for animals that have died due to heat resistant microorganisms such as spores of Bacillus anthracis. If incinerator facility is not available, dead animals and other materials can be burnt in a pit, preferably dug near the site of death. The pit or trench (about 0.5-meter-deep) is first filled with wood, making air spaces with the help of cross iron bars. Then the carcass is placed and ignited with the help of kerosene. After complete carcass is burnt, the trench is filled with mud. In Chemical treatment the animals die from diseases, which do not pose a potential health hazard, the carcass can be disposed of by usual means. Then the premises are treated with lime water (1:20) or with a suspension of bleaching powder (1:20). An aqueous solution of cresol or phenol is preferable for metal parts. Rendering Most economical method of carcass disposal. Movement of infected carcass from slaughter house to rendering plants, risky proposal. Carcass crushed into small uniform pieces and heated (130 °C for 3.5 hrs) under pressure. Fat, proteinaceous matter and water separated to yield products like meat meal, bone meal and tallow. (processing speed: 12 tonnes/hr). Discouraged in prion infected carcasses. Recontamination by Salmonella sp. during handling and transportation of finished product. Environmental concern: gas and odour emission. Overcome (90%) by using cold water washing, scrubbers and bio-filters. Composting is the process of placing carcasses is layers with a carbon source and manure to allow the natural healing process to break down the carcass and reduce its mass. Composting is an “art” that must be practiced because of the variety in materials, weather conditions and number of carcasses. It is best to have the same person doing the composting to consistently read the pile. Keep carcasses covered and at least 6” from sides, take and record temperature daily (must reach 130 F). Start with a base of carbon source material, put carcasses, litter and carbon source in layers. Mix pile at least 1 time when the temperature starts to decline; this will generate a new heat cycle after each mixing. Similar to burial but on a larger scale. Practiced when animal dies from a disease which do not pose potential health hazard. Necessary equipment’s, personnel, procedures and containment systems required. Transportation of carcasses pose risk of disease spread.
AUTOLYTIC CHANGES
Autolysis means self-digestion by the tissues enzymes that are present in or released into the cytoplasm of the cell after death.
Variation in autolytic changes in tissues: There is much variation among tissues in the content of proteolytic enzymes which accounts for the variation in the degree of autolytic changes among tissues. For example, in liver, pancreas and kidneys tissue changes relatively quickly whereas muscle tissue changes relatively little.
A brief general consideration about autolysis: Autolysis is rapid in certain tissues and results in liquefaction of the tissues e.g. in the pancreas and gastric mucosa. In other tissues e.g. fibrous tissue, autolysis is less rapid. Putrefaction in dead tissues occur when there is invasion by “protein splitting anaerobic saprophytic organisms”. This results in the formation of gas and variety of foul smelling substances which includes ammonia, hydrogen sulphide, indol, skatol and putrescent amines-like “putrisciene and cadaverine”. The tissue turns black or dark-green as a result of the formation of iron sulphide (FeS) from broken down haemoglobin. The common putrefactive organisms are those Clostridium species normally present in the GIT and therefore, the process occurs earliest in the abdominal cavity.
Different stages in autolysis
In general, post-mortem changes vary considerably with the (1) cause of death (2) atmospheric temperature (3) body temperature of the animal at the time of death (4) amount of time since death and (5) presence of bacteria in the tissue.
Algor mortis: Algor mortis is the gradual cooling of the body after death.
Rigor mortis: It is one of the most striking recognizable feature of the post-mortem change, characterized by the stiffening of all muscles after death and relates to the contraction of muscle fibres as ATP decreases. ATP may be re-synthesized from glycogen and that’s why delay rigor is found in well nourished/fed animal with high muscle glycogen. Rigor occurs more quickly in poorly nourished animals. Rigor mortis classically begins in two to six hours and passes off in one or two days.
Livor mortis: Livor mortis is the gravitational setting of blood to the down side of the animal (Hypostatic congestion). It is most evident in the lungs and the skin as dark red coloration or in the kidneys as a black zone of coloration in the cortex of one side, which has been called “pseudomelanosis”.
Post-mortem decomposition: It involves discoloration, softening, distension and displacement of tissues due to saprophytic organisms.
Discoloration of the tissues or organs results from the break-down of haemoglobin and the action of bacterial hydrogen sulphide (H2S) on haemoglobin (Hb(Fe)+H2S (Bacterial)= FeS (Iron sulphide) +H2 The pretty shades of blue, green and purple are only due to the above said reaction or changes. Softening of tissue or organs caused by “autolysis” with assistance from saprophytic bacteria or perhaps the normal flora of the tissue. This may be easily observed in liver and kidneys. The pancreas is very sensitive because of its enzymatic contents and softens rapidly which is accentuated by handling. Distension occurs largely because of fermentation with gas production in the digestive tract. The gas distends all parts from the stomach down and extreme pressures so built in some organs may rupture the organs or the abdominal muscle may be torn from which GIT organs may protrudeout.
Distension of the abdomen or intestines causes pressure effects in the viscera. Large areas of the live may become pale because of the blood has been pushed-out, or outlines of the loops of the intestine may be imprinted on the surface of the liver as a result of blood being pressed the liver from one area to another. Gas bubbles are often present in liver and kidneys, usually in pale areas of autolysis and putrefaction, which are not uniformly spread through the tissues. Post-mortem abdominal distension with push blood from the venous system in the abdomen make the viscera pale at the same time the hind limb muscles, lungs and neck region are very congested. The mucosa of the rumen will peel off in large patches easily because of autolysis. The intestinal mucosa may have an accumulation of cells and mucus on the surface as a result of autolysis and these changes may be easily confused with an inflammation of the intestine. Bile will seep from the gall bladder into nearby tissues and stain them yellowish-green. This is evident in any tissue in contact with the gall bladder and is often seen on the liver, stomach and mesenteric fat. Post-mortem clot and chicken fat clots must be differentiated from thrombosis.
References
- Chauhan, R.S., Singh, R. and Singh, K.P. (2007). Art of Disease Investigation including Collection, Preservation and Dispatch of Materials for Laboratory Diagnosis. PP 1-82. Director, V.R.I., Izatnagar U.P. (India).
- Rajan, A. and Valsala, V. (2002). Postmortem Examination. In : Handbook of Animal Husbandry. Indian Council of Agricultural Research, New Delhi, PP 1096-1119.
- Singh, R., Singh, K.P. and Chauhan, R.S. (2007). Manual of Diagnostic Pathology. Center for Animal Disease Research and Diagnosis, I.V.R.I., Izatnagar, U.P. (India).
- Sinha, B.K. (1994). Postmortem Techniques and Diagnostic Procedures with Interpretation. Chapter-1, PP 15-35. Pushpa Prakashan, Patna, Bihar (India).
- W. Pritchat (1955) Description in pathology-avoiding pathological description. Arch. Path. 59:612-617
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