After the death of animals, it is the responsibility of the owner to dispose of their carcasses in a way not harmful to the environment or public health.
Do not touch a diseased animal without protective clothing and gloves. If for some reason, contact without gloves has been made, wash the hands with a cleaning agent. For infected animals, take special precautions as states may have stricter disposal requirements. If there are signs of zoonotic disease like rabies, inform local animal health official immediately and clean the location with chemical disinfectant to prevent the infection from spreading further.
Methods of disposing of dead animals including burial, incineration, rendering and composting.
Burial is the most common and economical disposal method, but it requires thoughtful selection of the burial site. The carcass is wrapped in a plastic bag, placed in a box and buried underground. When selecting a burial site make sure there are no nearby underground water sources or areas that may flood to reduce the chance of water contamination. Another factor to consider is the type of soil; make sure the ground does not contain too much sand. Burial is difficult in the winter in colder climates.
Burning dead animals inside a fired incinerator is another way of disposing of carcasses. Incinerator ash is then buried underground. Burning is usually not economical due to the high energy and labor costs involved. Burial is usually preferable except in cases of specific diseases where state laws require disposal using incineration. Choose a location outside of public view and take safety precautions before burning.
Rendering is the process of converting dead animal bodies to pathogen-free useful byproducts such as protein for agricultural feed. Mammal carcuses are about 50 percent water and 20 percent protein. This is one reason alkaline processes are have become the preferred option. In this process, the carcasses are subjected to temperatures in the range of 130 C to 150 C via high-pressure steam to destroy pathogens. Rendering is not bio-friendly due to the transportation of dead animals to remote rendering plants and high risk of transferable mad cow disease. In recent years, use of rendering has decreased significantly due to increasing regulations and transportation costs.
Alkaline hydrolysis involves mixing the carcass with an aqueous solution of sodium hydroxide or potassium hydroxide and applying heat. Often solds as “digesters”, these units are promoted by their makers as using loess energy and producing less troublesome wastes than incinerators. The operate hotter than ambient temperature, but not nearly at the temperatures required to support combustion. Some operate at high pressure and a termp of 230 to 250 degrees F, similar to a pressure cooker. Others operate at ambient temperature and more moderate temps of 200 degrees F. The higher temperature and pressure promote faster decomposition. Cycle times can be as low as 6 hours (time from loading unit until final removal).
The Indiana-based company Bio-Response Solutions makes units of various sizes. The effluent is promised as sterile, including free of prions (which are suspected to cause Mad Cow Disease.) The solid remains are typically less than 5 percent the weight of the animal carcass. The liquid is removed and neutralized to a lower pH. Then it can be drained to the sewer and municipal water treatment system.
See also: Carcass disposal: A comprehensive review
This natural process allows microorganisms such as bacteria and fungi to decompose dead animals into organic matter. Composting is the preferred method on farms; it costs less as piles can be prepared readily with the equipment available on the farm. Composting of dead animals is considered a valid method by bio-security agencies in the US as the final product of composting can be used as fertilizer on fields.