Cleaning, Disinfection, and Sanitation in Shelter Medicine

The healthful operation of an animal shelter requires that the facility maintain a sanitary environment.

Preventing disease transmission through proper cleaning and disinfection techniques is far easier and more cost-effective than dealing with a disease outbreak. Veterinarians can help animal shelters develop efficient and effective protocols for cleaning, disinfection, and sanitation.

Protocols should balance benefits (ie, disease suppression) against the negative impact of overzealous procedures that inflict unnecessary stress on animals and contribute to disease expression.

Terms such as "cleaning," "disinfection," "sanitation," and "sterilization" have specific definitions as they apply to shelter medicine:

• Cleaning is the physical removal of organic material (fur, urine, fecal matter, dirt) from objects and surfaces (tidying and washing). Cleaning results in a visibly clean surface but might not kill or remove all microbial pathogens.

• Disinfection is the process of killing microbial pathogens on surfaces using a disinfectant.

• Sanitation can include both cleaning and disinfection of the kennel environment. The goal of sanitation is to decrease the presence of infectious organisms to below the disease transmission threshold (aiming to eliminate the presence of an “infective dose”).

• Sterilization is the destruction of all microbes. Sterilization is generally reserved for equipment necessary for sterile procedures, such as surgical instruments and gloves.

It is appropriate to have separate protocols for cleaning common areas, tidying and cleaning primary enclosures while occupied by the same animal or animals, disinfecting cages between animal occupants, and implementing deep cleaning and disinfection procedures in the case of a disease outbreak.

A primary enclosure can be kept tidy through spot cleaning during the continuous and ongoing occupation by an animal or a closed group of animals. Spot cleaning is less stressful to animals than being removed from the enclosure and returned to a space that has been stripped of familiar scents and instead smells of cleaner and disinfectant. Spot cleaning involves removing and replacing soiled bedding, removing visible debris by scooping feces and gently sweeping up spilled litter or kibble, and replenishing food and water. When spot cleaning, it is appropriate to follow scooping of feces with a focused application of a cleaning solution to remove any residue.

Once an animal is adopted out or otherwise vacates a primary enclosure, the enclosure must undergo full sanitation.

Sanitation protocols can be divided into a four-step process:

1. tidying

2. washing

3. disinfecting

4. drying

Because sanitation involves the application of chemicals and spraying with hoses, animals must always be removed from enclosures during the sanitation process.

Tidying, or dry cleaning, is like spot cleaning but on a larger scale. All materials are removed from the enclosure, and all debris and organic materials are wiped or swept up.  Because every effort must be made to minimize the creation of dust clouds, rubber squeegees should be used instead of brooms, and litter trays should be lowered deep into trash receptacles before gently tipping them out. Tidying in this manner decreases the spread of organic material that supports the persistence of infectious agents.

After all visible materials are removed, washing (scrubbing with detergent) can begin. Washing is best accomplished by applying detergent with a low-pressure foamer using hot water and then scrubbing with a bristle brush. The foam applicator helps apply the detergent to upright and overhead surfaces. In smaller spaces, where foamers are not appropriate, a squeeze bottle that produces a stream of diluted detergent can be used.

Scrubbing with detergent breaks down biofilms that can prevent the penetration of disinfectants. Scrubbing should proceed from top to bottom, with special attention paid to cracks, corners, and cage bars, where debris can accumulate.

After scrubbing, the detergent should be rinsed out using a low-pressure hose or wiped out with a water spritz and paper towels. High-pressure rinsing should be avoided because it aerosolizes bacteria and viruses that have not yet been inactivated by disinfectant.

Buckets and rags should not be used for washing, because they can be fomites—inanimate objects capable of transferring an infectious agent from one place to another.

While cages are being washed, all removed laundry, toys, dishes, and litter pans should also be washed and disinfected.

The washing step removes up to 99% of bacteria and prepares surfaces for the next step: disinfection.

Disinfecting involves diluting the disinfectant according to the manufacturer’s label and allowing the disinfectant to stay in contact with surfaces for the prescribed amount of time. Disinfectant selection should be based on the infective agents being targeted and the safety of the product for the species housed. Bleach is an inexpensive disinfectant that is effective against bacteria, parvoviruses, and respiratory viruses at a 1:32 dilution (0.5 cup/gallon) and against ringworm spores at a 1:10 dilution (1.5 cups/gallon); it requires a 10-minute wet exposure period. Limitations with bleach are that it is caustic, corrosive, and a respiratory irritant; bleach also requires daily dilution (ie, diluted solutions lose effectiveness and decompose over time, and bleach can be dangerous if used undiluted).

Other choices for disinfection include quaternary ammonium products, oxidizing agents, biguanides, and phenols. Each category of disinfectant has its own benefits and limitations. Veterinarians should work with animal shelters to determine the most useful, cost-efficient, and effective type for a particular shelter’s setting and population.

Drying is the removal of residual moisture after the specified wet disinfection exposure period. Drying must be complete before animals are returned to their enclosures. Air drying can be hastened with paper towels or a squeegee.

Fans are generally not recommended for drying, as they can blow respiratory irritant fumes around the shelter; however, they can be appropriate in some settings.

Animals returned to enclosures that are still wet with disinfectant may develop sores on or between their footpads, on the scrotum, on the tongue, or around the mouth. Some disinfectants must be rinsed after the specified disinfection period to be safe for animals to reoccupy the space, so careful disinfectant selection and use is essential.