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Controlling disease transmission in animal shelters for technicians (Proceedings)


The demand for better care has resulted in unprecedented interest and involvement of the veterinary community in shelter operations.

As the human animal bond has strengthened, the public has demanded more professional and compassionate care for homeless animals, rejecting the previously held notion that, unfortunately, the only or best solution to the pet overpopulation problem was humane euthanasia. This demand for better care has resulted in unprecedented interest and involvement of the veterinary community in shelter operations. The management of health care for dogs and cats housed in shelters differs in many ways from the methods employed in either private practice or other confinement situations such as kennels or laboratories. Without real data or shelter studies, veterinary professionals must often improvise and extrapolate from the veterinary literature to provide solutions to challenging shelter problems; but it is also becoming increasingly clear that intuitive judgments and traditional health care strategies are often ineffective in shelter settings. The volume of veterinary research regarding shelter medicine has increased in recent years, but some of it has only created more questions, leading to challenges to some of the more widely held beliefs regarding sanitation, stress reduction, ventilation, quarantine and even vaccination protocols in shelters. Clearly more research is needed to enrich the lives of shelter animals.

In order to work effectively with a shelter, it is imperative to understand the mission of the organization. Shelters typically fall into several different categories. They may be municipal shelters or private humane societies. Municipal shelters generally focus on animal control and thus public health protection and managing nuisance complaints. They may be further categorized as open admission facilities that offer a variety of community programs as well. Municipal or open admission shelters must accept all animals that are presented to them regardless of the condition or number of animals already in the facility, and often utilize euthanasia routinely to manage their population numbers and disease. This open admission policy can set the stage for uncontrollable disease transmission, especially if the shelter is already overcrowded, understaffed and must hold animals with obvious or inapparent infectious disease. Private humane societies or societies for the prevention of cruelty to animals (SPCAs) may or may not have the contract to provide animal control services to the community. In addition to offering several of their own animal welfare oriented programs, including spay neuter, behavior counseling, adoptions, etc, they may be known as limited admission, or "no kills" that can close their doors to avoid overcrowding or manage disease. They typically perform some euthanasia, but not as a matter of routine. However, by holding adoptable animals for longer periods in order to find homes, they sometimes extend themselves beyond their capacity to provide humane and adequate care and end up with disease problems. Private organizations and individuals may act as sanctuaries or rescue groups, often operating from the owner's home. None of these entities has an affiliation with an "umbrella" national organization such as the ASPCA or HSUS and there are no federal care guidelines. There are only a few state regulations regarding shelter operations.

Although shelters may have different goals and resources, the overriding mission of all facilities should be to provide a clean, comfortable and safe environment that addresses the emotional and physical needs of the individual animal and minimizes their stress. The control of disease transmission must continually be addressed, recognizing that some disease may be inevitable because of the constant introduction of new animals who are potentially diseased, and the interaction between host, environment and agent factors. Shelter animals are more vulnerable to disease transmission because of their often-debilitated conditions (i.e. they may be stressed, sick, injured, malnourished, parasitized, etc.) and the increased risk of exposure to disease from other animals in the facility. In addition to exposure to sick animals, disease agents may be endemic in a physical environment that may be damp, subject to temperature fluctuations, shoddily constructed or dilapidated, poorly ventilated, difficult to clean and sanitize and overcrowded. Some pathogens (i.e. parvovirus, calicivirus and ringworm spores) can survive for long periods of time in the environment and are also difficult to inactivate; others have carrier states (herpes, calici virus) and shedding periods (parvo) that make disease detection and control difficult. Identification of and a thorough understanding of each pathogen is required to prevent and manage disease outbreaks; in addition to understanding pathogenesis, epidemiology, morbidity and mortality rates, there should be a thorough knowledge about carrier states, shedding periods, modes of transmission, survival rates in the environment, which chemicals can inactivate and so on.

Recommendations for creating a comprehensive shelter health care program focus on four general areas: shelter design and housing, sanitation, stress reduction through good husbandry and a sound veterinary medical program that includes data collection and medical recordkeeping as an integral part of the plan. Each will be briefly described below.

Shelter design: The design of a suitable shelter environment is very different from that of the typical veterinary hospital. It is recommended that all shelters have as many areas as possible to house animals to allow for flexibility in managing the needs of the population. There should be, at a minimum, separate areas for 1) animal intake, 2) physical segregation of animals by species, and age, (including exotics and wildlife) 3) isolation of diseased, debilitated and injured animals 4) adoptions 5) exercise and play areas and 6) quarantine when necessary. Animal control shelters should segregate healthy adoptable strays from unhealthy ones and have multiple areas that can be adapted for different purposes, such as long-term holding for animals involved in cruelty cases, bite quarantines and other legal cases. Animal holding areas should be constructed of rugged, non-porous materials that can withstand repeated vigorous cleaning and disinfecting, as these activities may occur at least once daily, sometimes more frequently.

Various housing designs should be available. Shelters that provide group housing must also have single unit housing for special needs animals and resist the temptation to overcrowd the group units. Ideally, aggressive animals and adoptable animals should each be housed in runs with a guillotine door so the enclosure may be safely cleaned without handling the animal and to minimize disease transmission. Cats should be assigned a second cage or their own transfer carrier to hold them when cleaning their cages. There must be sufficient space in each space for animals to be able to turn around, walk, stand, lie down with legs fully extended and distance themselves from waste products. Spaces should be enriched; dogs should have platforms or bedding and toys; cats should have perches, beds, toys and hiding places. Strong and destructive dogs should be housed in enclosures they cannot break out of or destroy.

Sanitation: Maintaining a sanitary environment is a challenge for all shelters. Veterinarians should never underestimate the importance of designing and overseeing the sanitation process. It is imperative to develop a consistent routine (same staff, same time each day) that utilizes the best methods for disinfecting the environment properly but minimizes stress to the animals. The appropriate chemicals must be selected, mixed and applied according to the manufacturers' instructions or they will be ineffective. The frequency of complete disinfection (which requires removing the animal from its enclosure) depends on their health status and whether the animals reside in the same cage for their entire stay. Everything should be disinfected or discarded whenever a new resident is moved to a cage; otherwise, daily spot cleaning may suffice in stable cat colonies whose members appear healthy or disease free.

Most shelters rely heavily on chemical disinfectants but the value of ultraviolet light, drying and steam heat should not be overlooked. Quaternary ammonium products are commonly used in shelters to chemically disinfect animal areas, but despite their labeling, various studies have shown that they are not parvocidal. The best products that shelters can readily obtain that reliably kill parvo and calici virus are sodium hypochlorite (bleach 5.25%) and potassium peroxymonosulfate, otherwise known as Trifectant. The bleach (5.25%) should be diluted 1:32 with water, but in the case of ringworm, the dilution is 1:10. Because fomites (inanimate objects such as clothing and equipment) are believed to be the most common way diseases are spread, everything in animal areas must be cleaned and disinfected, including all cage and enclosure surfaces, door knobs, all equipment, drains, ventilation ducts, etc. Staff training must be provided to ensure their compliance with the protocols. Frequent hand washing is advised, as well as the strategic placement of hand sanitizers with 70% alcohol in all animal areas. Staff who cleans multiple areas should start in areas with the healthy and most vulnerable animals, i.e. with juveniles or in adoptions areas, and finish in disease areas (isolation) last. Clothing should be properly sorted and laundered in hot water and bleach. All cleaning equipment should be dedicated for use in one area only, but this is especially important in areas that house diseased animals. It is important to take the time to review and observe sanitation methods firsthand whenever evaluating or advising a shelter regarding disease prevention. Unfortunately, staff mistakes and shortcuts regarding sanitation procedures are not uncommon.

Stress reduction: Stress reduction plays a key part in any shelter health care plan. Shelters are inherently stressful due to their environmental conditions and the emotional and physiological stress of the animals themselves. Research has shown that the stress from re-housing cats causes recrudescence of the herpes virus that causes upper respiratory infections, hence the current recommendation to limit rehousing of cats for sanitation purposes. Cages should be cleaned by removing soiled litter, dirty bedding and disposable food trays etc, cleaning soiled surfaces and tidying up the area. The cat can remain in the cage during these procedures, with care taken to avoid creating undue stress during the process. (However, the animal(s) should be removed in order to effectively disinfect the cage or enclosure.) The simple strategies listed here can be employed to minimize the impact of stress on animal health. 1) Most importantly, avoid overcrowding; 2) Provide a good quality, balanced diet that meets the needs of individual animals; avoid poor quality, generic or expired food; 3) Provide good ventilation, comfortable and stable environmental conditions; 4) Turn the lights off at night so animals can rest and sleep; 5) Keep noise levels to a minimum; 6) Provide behavioral enrichment, including human contact, toys, play time, dog walking, etc; 7) Establish routine times for procedures, using the same staff in each area to establish familiarity and a comfort level with the animals; 8) Separate animals by species, heath status, age, predator prey status, etc.

Veterinary health care program: The veterinary healthcare program varies between shelters for a variety of reasons, but the focus should always be on disease prevention rather than treatment. Shelters are not hospitals, and decisions to treat contagious disease in-house should be evaluated carefully in terms of time, labor and dollar costs; the risk of spreading disease throughout the entire facility by treating highly infectious diseases in-house may be high and endanger the lives of more animals and lower staff morale and public confidence in the program. Once the decision is made to treat, quality care that prevents suffering must be provided, and there should be enforcement of protocols, follow-up and accountability for failure to follow treatment guidelines. Difficult decisions may have to be made to stop treatment in cases that are non- responsive, there is animal suffering or when continuation endangers the lives of the rest of the population. It is important to maintain accurate and complete medical records of all procedures performed and to collect data to be able to determine the source of the infection, movement of infected animals throughout the facility, assess risk to current residents and incoming animals and so on.

The health care program should minimally include the following components

1) Examination at the point of intake so diseased, injured and debilitated animals can be isolated quickly and provided with timely care, including appropriate analgesia.

2) Vaccinations at the point of intake of as many animals as possible within the resources of the program. The core canine vaccines for shelters include modified live (MLV) distemper, hepatitis, parainfluenza and parvo. Puppies should be given boosters every 2 weeks until they reach 5 months of age. If kennel cough is a problem, consider adding the intranasal vaccine with bordetella, parainfluenza and adenovirus; it provides faster protection but it may cause mild symptoms of disease that are difficult to differentiate from true clinical disease. The core feline vaccines for shelters include MLV panleukopenia, herpes and calici virus. Kittens should be given boosters every 2 weeks until they reach 4 months of age. If upper respiratory infections are a problem, the intranasal bivalent herpes and calici or bordetella vaccine may be useful, but may also cause mild symptoms that can be confused with true clinical disease. (Avoid use of the intranasal panleukopenia vaccine, especially in kittens). Upon release from the shelter, rabies can be given by a licensed veterinarian or in accordance with local and state regulations that may allow shelter staff to administer;

3) Deworming of all cats and dogs with a safe, broad spectrum anthelmintic in accordance with guidelines from the Centers for Disease Control (CDC) or Companion Animal Parasite Council (CAPC). The guidelines require deworming every two weeks until the animal reaches 3 months of age, then once a month until 6 months of age, then testing and deworming periodically as indicated. (See www.cdc.gov or www.capcvet.org for complete details and a list of recommended anthelmintics.) They should also be placed on a heartworm preventative in accordance with guidelines from the American Heartworm Society for testing and preventative care (www.heartwormsociety.org). Many shelters have resorted to using coccidiocidal drugs such as ponazuril to treat stubborn cases of coccidiosis instead of the common small animal coccidiostatic drugs that seem less effective. Coccidiosis is not uncommon in shelter animals and should be a suspect in unthrifty animals even if their stools and fecal samples appear to be normal.

4) Treatment of the animals and the environment for fleas and ticks and other external parasites;

5) Diagnostic disease testing and routine screening for certain diseases. Routine retrovirus testing (FeLV, FIV) of all cats is desirable but not always possible, especially in shelters with a high turnover of the population; however, screening is strongly advised for cats entering shelter group housing or being adopted into multiple cat households, and before neutering or treating animals. It should be remembered that the American Association of Feline Practitioners (AAFP) advises that no healthy cat should be euthanized based upon the results of a single positive FeLV or FIV test. Heartworm testing of dogs over 7 months of age is recommended. Parvo and other disease testing may be limited to situations involving outbreak management, paying special attention to the sensitivity and specificity of the tests.

6) Daily rounds by veterinary staff or technicians to continually assess health and behavior, detect problems in previously examined animals and to collect and manage population data;

7) Written guidelines for routine and emergency treatment. The guidelines should be part of a standard operating procedure that is made available to all staff working with the animals so that injured and diseased animals may receive prompt veterinary attention

8) High quality, high volume spay neuter programs for the shelter animals. Neutering all animals that are adopted from the shelter should be an integral part of the strategy to reduce the intake of unwanted animals, but in order to have a true impact on shelter intake, programs must also neuter animals who belong to the public; and

9) Euthanasia when necessary to manage overcrowding and control disease when other methods of reducing the population numbers and controlling disease transmission have failed. Managing population numbers to match resources helps ensure that quality of life care and conditions can be provided for all shelter residents. Euthanasia should also be considered for animals that are unsuitable for rehoming.

Shelter medicine has increased in popularity in the past few years as evidenced by the growth of the Association of Shelter Veterinarians (ASV at www.sheltervet.org), and the development of shelter medicine courses and residencies at various universities, on VIN and at major veterinary and animal welfare conferences. Veterinarians are urged to use the shelter medicine resources that are available to them, such as the website at www.aspca.org or www.sheltermedicine.com, and recognize that implementing successful shelter health care protocols often involves developing unique programs have many non-traditional components to them. Private practitioners should bear two things in mind when confronted with shelter medicine practices that differ from what they are familiar with: 1) some shelter practices are validated by research that does not always reach veterinarians engaged in mainstream private practice and 2) other shelter practices are often based on anecdotal information, networking and practical experience. It often takes a bit of both to operate a successful program.

References available upon request from the author at lilam@aspca.org.

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