Page 107 - SpeedhorseMarch2021

VETERINARY VIEWS
TYPES OF DISINFECTANTS
Germicidal activity depends on chemical concentration, temperature, pH of the solution, and the presence of organic debris. No single disinfectant possesses all desirable characteristics such as: a) the ability to kill all pathogens; b) is non-toxic to horse and human; c) is environmentally safe and biodegradable; d) does not destroy or corrode surfaces; and e) is stable and effective at wide temperature ranges. Often, there needs to be a compromise as to which of these features is the most important for your situation. The key for success is in using the disinfectant correctly.
PEROXYGEN COMPOUNDS
Accelerated hydrogen peroxide (AHP by Virox) is a useful general-purpose disinfec- tant. AHP is composed of hydrogen peroxide, surfactants and wetting agents to maximize penetration, and chelating agents to reduce water hardness. Not only is it relatively safe
to use and doesn’t persist in the environment, but it functions as a cleaning agent as well as a disinfectant. It can be used on most surfaces, although discoloration or pitting may occur on copper, brass, or non-ferrous metals.
Another effective broad-spectrum germi- cidal peroxygen compound against equine viruses and bacteria is Virkon S (by Dupont). It is somewhat more caustic than AHP but quite effective.
CHLORINE
Chlorine bleach is an effective disinfectant provided surfaces are pre-cleaned to remove all organic matter, which would otherwise inactivate the chlorine as a germ-killing agent. Chlorine bleach is not only readily available and very inexpensive, but it is an extremely effective broad-spectrum germicidal chemical, targeting gram negative and gram-positive bacteria as well as spore-forming bacteria (Clostridia) and some viruses. Read the label instructions but as a general rule, mix 1/4-cup of household bleach in 1 gallon of water.
Never use chlorine in an undiluted form and never mix with other chemicals as it can form toxic gases. Always wear protective gear, especially for the respiratory tract and eyes. Be cautious in using on metal, plastic or some fabrics, as it can damage those materials.
QUATERNARY AMMONIUM COMPOUNDS (QUATS)
Ammonium chloride as an example of a quaternary ammonium compound is ineffective in the presence of organic matter, so surfaces being treated must be cleaned thoroughly. It has low toxicity and minimal risk of causing irrita- tion. Its use must be coupled with an appropriate detergent, i.e. one that is not anionic.
PHENOLS
Phenolic disinfectants not only kill viruses, bacteria and fungi, but are also effective despite the presence of organic debris.
However, they are carcinogenic and envi- ronmentally unfriendly. In addition, phenols are highly corrosive to metal, should not be used in the presence of cats, and cannot be used with cationic or non-ionic detergents.
ALDEHYDES
While formaldehyde or glutaraldehyde is efficacious even in the presence of organic mat- ter, their toxicity and carcinogenicity render these a poor choice for use on the farm.
BIGUANIDES
Chlorhexidine is an example of this class of disinfectants. Its germicidal activity works within a specific pH and also cannot be used with anionic detergents. Organic matter inac- tivates its disinfectant capabilities.
IODOPHORS
Povidone iodine used at a 10% concentra- tion is efficacious as a disinfectant against both viruses and bacteria. It is useful for hand washing and equipment cleaning, but prob- ably not as useful for addressing an entire barn – not only might it be cost prohibitive but it also can stain certain surfaces.
ALCOHOL
Ethyl or isopropyl alcohol (at concentra- tions of at least 65%) is able to inactivate
some bacteria, fungi, and some viruses (as for example, the current COVID-19 coronavirus). However, alcohols are rendered ineffective in the presence of organic debris and in addition, alcohol is flammable.
DETERGENT DISINFECTANTS
“Detergent disinfectants” are intended for use as a one-step process. While the detergent con- tains surfactants to help break up organic matter on a surface, a sanitizer reduces the amount of microbial contamination on inanimate surfaces to a level that is considered “safe.” Nonetheless, as a one-step process, these are not particularly effective in an equine environment coated with copious organic debris.
For the important multi-step process of cleaning and disinfection, confer with your veterinarian to determine an appropriate cleaning and disinfection plan for your unique facility and situation.
Items such as rakes, shovels and wheelbarrows should be disinfected separately – clean and rinse thoroughly. Then, place them in the sun to dry – ultraviolet also has germicidal effects.
High-pressure washing helps to clean porous surfaces; however, the force of high-pressure water may aerosolize microorganisms and contaminants, which contributes to further environmental contamination.