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54 Tasks for the Veterinary Assistant

There are three levels of cleaning: cleaning, disinfect- time is, and if they are affected by time, temperature,
ing, and sterilizing. pH, or organic materials. Let’s look at four of the most
common disinfectants.
Cleaning
1. Chlorine (sodium hypochlorite) or bleach is an
excellent disinfectant; bactericidal (regular and
Cleaning is when we mix a detergent like dish or clothes spore‐forming, i.e., yeast), viricidal, and fungicidal.
soap with water. It lifts the soil and debris from the sur- Bleach has a phenol coefficient of 40. For general
face. The water then carries the soil and debris to the use it is diluted 1 : 32 but needs to be stronger to
bucket, or wash tub via a mop or cloth. Cleaning reduces destroy ringworm fungus so it is diluted at 1 : 10 if
microbes but not sufficiently to prevent nosocomial ringworm is suspected. Bleach is deactivated by
infections. Cleaning is carried out prior to disinfecting organic material, sunlight, and time. Diluted bleach
because many disinfectants do not penetrate through is only effective for 24 hours. To use it properly,
heavily soiled or debris‐filled surfaces. Many are also clean up visible debris with a detergent and water
deactivated if they come into contact with organic combination, then spray with bleach and allow to air
material. When cleaning it is important to use clean dry. It is important to make sure the surfaces are
cloths, mops, or paper towels. Paper towels are the best completely dry before allowing a pet onto the
choice as they are used once and disposed of. Wash surface as bleach, even diluted, is harmful to skin.
cloths and mops, if allowed to get dirty or contaminated 2. Quaternary ammonium compounds
with debris like feces or vomit, become saturated with (quats) – Parvosol II™, and Roccal‐d™ – are very
microbes and become fomites.
effective against bacteria and viruses, good against
fungi, amoebas, and enveloped viruses. They are not
Disinfecting very effective against endospores or non‐enveloped
viruses. Dilutions vary with each product so read the
Disinfecting is the use of specific chemicals that reduce labels or MSDS carefully. Quats are commonly used
the number of microbes substantially on inanimate or to soak sharp surgical instruments like scissors.
animate surfaces. There are two types of disinfecting However, they lose their efficacy if coming into
chemical compounds: contact with organic material like blood. It is
important that instruments are cleaned and rinsed
Disinfectants used only on inanimate objects well before soaking them in a quat.
Antiseptics used only on living tissues
3. Hydrogen peroxide – Rescue™ is a 4.25% hydrogen
Disinfectants require accurate dilutions to be safely peroxide. Hydrogen peroxide is usually considered
used. Carefully measuring the disinfectants as they are an antiseptic, but at 4.25% it is a broad‐spectrum
put in spray bottles, or added to mop buckets, washing disinfectant of inanimate objects. Contact time
machines, and sinks is very important for them to work varies with the pathogens it kills; the longer it stays
well. They usually do not do well if an area is extremely on the surface, the more types of pathogens it
grimy or full of debris. Surfaces should be cleaned with destroys. The average time is 5 minutes, but a
detergent and water to remove the visible contaminates. stronger dilution can destroy pathogens in 3
Then the area is sprayed or mopped with the diluted dis- minutes. Rescue™ can be purchased as ready‐to‐use
infectant and allowed to air dry for the necessary time to wipes, ready‐to‐use spray bottles, or concentrates.
destroy pathogens. Some disinfectants need less time, There is also a shampoo version that can be used on
but you must wait the entire amount of contact time animals with skin infections.
before wiping it dry with paper towels. Contact times can 4. Benzalkonium chloride is a broad‐spectrum disin-
vary from 1 minute to 30 minutes depending on the fectant effective against coliforms, gram‐positive and
pathogen of concern. For example, spore‐forming gram‐negative bacteria, and yeasts. It is non‐
bacteria are the hardest to kill and so require more corrosive to metals, eco‐friendly, biodegradable, and
contact time. tissue friendly. It comes in a highly concentrated
Contact time is determined using the phenol coeffi- form that can be used for cleaning and disinfecting
cient; this is the “kill strength” of a disinfectant. For surfaces throughout the clinic.
example, if a disinfectant product has a phenol coeffi- 5. Alkalis (lye) and formaldehyde are extremely toxic
cient of 50 it is capable of destroying half of the microbes agents that are not used as standard disinfectants.
compared to the same number destroyed by phenol. However, lye is used to treat soil contaminates,
Several disinfectants are used in a veterinary facility. If especially if the contamination is animal carcasses.
unfamiliar with them read the label and Material Safety Formaldehyde is a fixative that stops the maturation
Data Sheets (MSDS) to find out what pathogens they process in living tissue. Both agents are highly
destroy, how to dilute them properly, what the contact dangerous to use and are carcinogenic. Respirators