GENERAL BIOSECURITY GUIDELINES

Contaminated hands are the most common source of infectious agent transmission in the hospital environment. Fingernails of personnel having patient contact should be cut short. Hands should be washed before and after attending to each individual animal as follows. Collect clean paper towels and use to turn on water faucets, wash hands for 30 seconds with antiseptic soap being sure to clean under fingernails, rinse hands thoroughly, use the paper towel to dry hands, and use the paper towel to turn off the water faucets. Use of antiseptic lotion should be encouraged. Personnel should not touch patients, clients, food, doorknobs, drawer or cabinet handles or contents, equipment, or medical records with soiled hands or gloves.

All employees should wear an outer garment, such as a smock or scrub suit, when attending to patients. Footwear should be protective, clean, and cleanable. A minimum of two sets of outer garments should always be available, and they should be changed immediately after contamination with feces, secretions, or exudates. Equipment such as stethoscopes, pen lights, thermometers, bandage scissors, lead ropes, percussion hammers, and clipper blades can be fomites and should be cleaned and disinfected after each use with animals likely to have a transmissible infectious disease. Disposable thermometer covers or thermometers should be used.

To avoid zoonotic transfer of infectious diseases, food or drink should not be consumed in areas where animal care is provided. All areas where animals are examined or treated should be cleaned and disinfected immediately after use, irrespective of infectious disease status of the individual animal.

PATIENT EVALUATION

Prevention of infectious diseases starts with the front desk personnel. Staff should be trained to recognize the presenting complaints for the infectious agents in the geographic area of the hospital. Animals with gastrointestinal or respiratory diseases are the most likely to be contagious. Infectious gastrointestinal disease should be suspected in all dogs and cats with small- or large-bowel diarrhea whether the syndrome is acute or chronic. Infectious respiratory disease should be suspected in all dogs and cats with sneezing (especially those with purulent oculonasal discharge) or coughing (especially if productive). The index of suspicion for infectious diseases is increased for dogs or cats with acute disease and fever, particularly if the animal is from a crowded environment such as a breeding facility, boarding facility, or shelter.

Front desk personnel should indicate clearly on the hospital record that gastrointestinal or respiratory disease is present. If the presenting complaint is known before admission into the hospital, an optimal method would be to meet the client in the parking area to determine the infectious disease risk before the pet enters the hospital. If an infectious gastrointestinal or respiratory disease is suspected, the animal should be transported (i.e., not allowed to walk on the premises) to an examination room or the isolation facility. If a patient with acute gastrointestinal or respiratory disease is presented directly to the reception desk, the receptionist should contact the receiving clinician, technician, or student immediately and coordinate placement of the animal in an examination room to minimize hospital contamination. Animals with suspected infectious diseases should be treated as outpatients if possible. If hospitalization is required, the animal should be transported to the appropriate housing area by the shortest route possible, preferably with a gurney to lessen hospital contamination. The gurney and any hospital materials in contact with potentially contaminated employees (including examination tables and doorknobs) should be immediately cleaned and disinfected as previously mentioned.

HOSPITALIZED PATIENTS

If possible, all animals with suspected infectious diseases, such as Salmonella spp., Campylobacter spp., parvovirus infection, kennel cough syndrome, acute feline upper respiratory disease syndrome, rabies, or plague, should be housed in an isolated area of the hospital. The number of staff members entering the isolation area should be kept to a minimum. On entry into the isolation area, outerwear should be left outside and surgical booties or other disposable shoe covers should be placed over the shoes. Alternatively, a foot bath filled with disinfectant should be placed by the exit and used when leaving the area. The room should be entered and a disposable gown (or smock designated for the patient) and latex gloves should be put on. A surgical mask should be worn when attending cats with plague, and extreme care should be taken to avoid being bitten. Separate equipment and disinfectant supplies should be used in the isolation area.

All biologic materials submitted to clinical pathology laboratories or diagnostic laboratories from animals with suspected or proven infectious diseases should be clearly marked as such. Fecal material should be placed in a plastic, screw-capped cup with a tongue depressor or while the clinician is wearing gloves. Place the cup in a clean area and place the lid on with a clean, gloved hand. Remove the used gloves and place the cup in a second bag clearly marked with the name of the infectious disease suspected. The outer surface of the bag should be disinfected before leaving the isolation area.

Disposable materials should be placed in plastic bags in the isolation area. The external surfaces of the bags should be sprayed with a disinfectant before being removed from the isolation area. After attending to the patient, contaminated equipment and surfaces should be cleaned and disinfected, and contaminated outer garments and shoe covers should be removed. Hands should be washed after discarding the contaminated outerwear. Dishes and litter pans should be cleansed thoroughly with detergent before returning them to the central supply area of the hospital. Optimally, materials such as outerwear and equipment to be returned to the central supply area should be placed in plastic bags and sprayed with a disinfectant before transport. Procedures requiring general hospital facilities such as surgery and radiology should be postponed to the end of the day, if possible, and the contaminated areas disinfected before use with other animals. Animals should be discharged by the shortest path to the parking lot possible.

Some animals with infectious diseases can be maintained in the general hospital boarding or treatment areas with special management techniques. For example, cats positive for the feline leukemia virus (FeLV) or feline immunodeficiency virus (FIV) should not be placed in the isolation area, if possible, to avoid exposing them to other infectious agents. Because neither of these two viruses is transmitted by aerosolization, cats with these infectious diseases can be housed in close proximity to other cats. The cages should be labeled appropriately, and the infected cats should not be caged next to or above seronegative cats. In addition, no direct contact or sharing of litter boxes or food bowls should occur between infected and naïve cats.

BASIC DISINFECTION PROTOCOLS

To lessen the spread of potential infectious agents, hospitalized animals should never be moved from cage to cage. The key to effective disinfection is cleanliness. Cage papers and litter boxes soiled by feces, urine, blood, exudates, or respiratory secretions should be removed and placed in trash receptacles. Bulk fecal material should also be placed in trash receptacles.

Many infectious agents are resistant to disinfectants or require prolonged contact time to be inactivated (Greene, 2006). Contaminated surfaces, including the cage or run floors, walls, ceiling, door, and door latch, should be wetted thoroughly with a disinfectant that is then blotted with clean paper towels or mops. Surfaces should be in contact with the disinfectant for 10 to 15 minutes if possible, particularly if known infectious agents are present. Soiled paper towels should be placed in trash receptacles. If infectious disease is suspected, the trash bags should be sealed, the surface of the bag sprayed with a disinfectant, and the trash bags discarded.

Contaminated surfaces in examination rooms should be cleaned to remove hair, blood, feces, and exudates. Examination tables, countertops, floors, canister lids, and water taps should be saturated with disinfectant for 10 minutes. Surfaces should be blotted with paper towels until dry, and the soiled towels should be placed in a trash receptacle. Urine or feces on the floor should be contained with paper towels, blotted, and placed in trash receptacles. The soiled area of the floor should be mopped with disinfectant.

Disinfectants are relatively effective for viral and bacterial agents but require high concentrations and long contact times to kill parasite eggs, cysts, and oocysts. Cleanliness is the key to lessening hospital-borne infection with these agents; detergent or steam cleaning inactivates most of these agents. Litter pans and dishes should be thoroughly cleaned with detergent and scalding water.

VACCINE TYPES

Vaccines are available for some infectious agents of dogs and cats and can be administered to prevent infection or limit disease. Vaccination stimulates humoral, mucosal, or cell-mediated immune responses. Humoral immune responses are characterized by the production of immunoglobulin M (IgM), IgG, IgA, and IgE class antibodies, which are produced by B-lymphocytes and plasma cells after being presented an antigen by macrophages. Binding of antibodies to an infectious agent or its toxins helps prevent infection or disease by facilitating agglutination (viruses), improving phagocytosis (opsonization), neutralizing toxins, blocking attachment to cell surfaces, initiating the complement cascade, and inducing antibody-dependent cell-mediated cytotoxicity. Antibody responses are most effective in controlling infectious agents during extracellular replication or toxin production. Cell-mediated immune responses are mediated principally by T-lymphocytes. Antigen-specific T-lymphocytes either destroy the infectious agent or mediate destruction of the agent by producing cytokines that stimulate other white blood cells, including macrophages, neutrophils, and natural killer cells. Cell-mediated immunity is required for the control of most cell-associated infections.

Currently available vaccines are either infectious (attenuated [modified-live] organisms or live virus–vectored recombinant vaccines) or noninfectious (killed virus, killed bacteria [bacterins], and subunit vaccines).

Attenuated vaccines replicate in the host to effectively stimulate an immune response and therefore generally have low antigen mass and do not require adjuvants. Different products are administered locally (e.g., modified-live Bordetella bronchiseptica intranasal vaccine) or parenterally (e.g., modified-live canine distemper vaccine). In live virus–vectored recombinant vaccines, the specific DNA that codes for the immunogenic components of the infectious agent is inserted into the genome of a nonpathogenic organism (vector) that will replicate in the species being vaccinated. As the vector replicates in the host, it expresses the immunogenic components of the infectious agent, resulting in the induction of specific immune responses. Because the virus-vectored vaccine is live and replicates in the host, adjuvants and high-antigen mass are not required. Because only DNA from the infectious agent is incorporated into the vaccine, no risk of reverting to the virulent parent strain exists, as occasionally occurs with attenuated vaccines. Only vectors that do not induce disease in the animal being vaccinated are used. Another advantage to vaccines of this type is the potential ability to overcome inactivation by maternal antibodies.

Killed virus, killed bacteria (bacterins), and subunit vaccines are noninfectious and therefore usually require higher antigen mass than infectious vaccines to stimulate immune responses because they do not replicate in the host. Some noninfectious vaccines may stimulate immune responses of lesser magnitude and shorter duration than infectious vaccines unless adjuvants are added. Adjuvants improve immune responses by stimulating uptake of antigens by macrophages that present the antigens to lymphocytes. Although adjuvants have historically been associated with vaccine adverse effects, newer generation adjuvants induce less inflammation. Subunit vaccines can be superior to killed vaccines that use the entire organism because only the immunogenic parts of the organism are used, which may decrease the potential for vaccine reactions. However, for some infections use of only one antigen does not adequate induce adequate protection. Native DNA vaccines and gene-deleted vaccines are currently being evaluated for several infectious diseases.

VACCINE SELECTION

Selection of optimal vaccines for use in dogs and cats is complicated. Multiple products for most infectious agents are available, but efficacy studies that directly compare different products are generally lacking. The veterinarian may need to choose from infectious and noninfectious options for the same vaccine antigen. Some vaccine antigens are for intranasal administration and others are for parenteral administration. Not all vaccines for a given infectious disease are comparable in every situation. Long-term duration of immunity studies and studies evaluating a vaccine’s ability to block infection by multiple field strains are not available for all individual products. When making decisions about which products to use or when evaluating a new vaccine, the practitioner should request information concerning efficacy, challenge studies, duration of immunity studies, adverse reactions, and cross-protection capability. Vaccine issues are commonly debated in veterinary journals and continuing education meetings; these are excellent sources of current information.

Not all dogs and cats need all available vaccines. Vaccines are not innocuous and should only be given if indicated. The type of vaccine and route of administration for the disease in question should also be considered. A benefit, risk, and cost assessment should be discussed with the owner of each individual animal before determining the optimal vaccination protocol. For example, FeLV only lives outside the host for minutes; it is highly unlikely that an owner would bring the virus into the household. Therefore cats housed indoors are not likely to come in contact with the virus.

Before administering vaccines, the animal should be evaluated for factors that may influence the ability to respond to the vaccine (Box 94-2) or that may affect whether vaccination could be detrimental. Hypothermic animals have poor T-lymphocyte and macrophage function and are unlikely to respond appropriately to vaccination. Dogs with body temperature above 39.7° C respond poorly to canine distemper virus vaccines; this may be true for other vaccines as well. Immunosuppressed animals, including those with FeLV infection, FIV infection, canine parvovirus infection, Ehrlichia canis infection, and debilitating diseases, may not respond appropriately to vaccination; modified-live vaccines occasionally induce the disease in these animals.

If high levels of specific antibodies are present, vaccine efficacy is diminished. This is a particularly important consideration when vaccinating puppies or kittens from well-vaccinated dams. Disease may also develop in vaccinated puppies and kittens because infection had already occurred and was incubating when the animal was vaccinated. Vaccines can be rendered ineffective from mishandling. Vaccines should not be administered while the animal is under anesthesia because efficacy can be diminished; if a vaccine reaction occurs, it may be masked by the anesthesia.

Adverse reactions can potentially occur with any vaccine. However, they are relatively uncommon in dogs and cats. In a recent study of more than 1.2 million dogs, the overall rate of adverse reactions was 38.2/10,000 dogs that had received vaccines within the previous 3 days (Moore et al., 2005). In a recent study of 496,189 cats, the overall rate of adverse reactions was 51.6/10,000 cats that had received vaccines within the previous 30 days (Moore et al., 2007). Vaccination has been associated with soft tissue sarcomas in some cats and can be life threatening. These tumors can occur after administration of infectious or noninfectious vaccines. Intranasal products can result in transient sneezing and coughing. Feline vaccines for which the viruses were grown on Crandall Rees feline kidney cell cultures induce antibodies that cross-react with feline renal tissues (Lappin et al., 2005), and some hypersensitized cats have developed lymphocytic-plasmacytic interstitial nephritis (Lappin et al., 2006b). Whether this results in renal disease is currently unknown. Suspected adverse reactions to vaccination should be reported (Paul et al., 2006). Administration of any vaccine to animals with proven vaccine-associated sarcoma or immune-mediated diseases, such as immune-mediated polyarthritis, immune-mediated hemolytic anemia, immune-mediated thrombocytopenia, glomerulonephritis, or polyradiculoneuritis, is questionable because immune stimulation may exacerbate these conditions.

For some infectious agents, including canine distemper virus, canine parvovirus, feline panleukopenia virus (FPV), feline calicivirus (FCV), and FHV-1, serologic test results have been shown to correlate to resistance to disease on challenge in some studies. The advantages and disadvantages of the use of serologic testing were recently reviewed (Moore et al., 2006). If validated laboratories or kits are used, results can be used accurately to make vaccination decisions for some dogs and cats (Lappin et al., 2002). For example, previously vaccinated animals that were presumed to have had a vaccine reaction and are still at risk of exposure to infectious agents could be assessed by serologic testing in lieu of arbitrary vaccination. In general, the positive predictive value of these tests is good (i.e., a positive test result usually predicts resistance on challenge).

VACCINATION PROTOCOLS FOR CATS

A physical examination, fecal parasite screen, and vaccine needs assessment should be performed at least yearly for all cats. The American Association of Feline Practitioners (AAFP) recently published the third version of the Feline Vaccine Advisory Panel Report (Richards et al., 2006; http://www.catvets.com). These guidelines are an excellent source of information for veterinarians to use when individualizing vaccination protocols. Vaccine antigens were divided into those that were considered core (FPV, FCV, FHV-1, and rabies), noncore (FeLV, FIV, Bordetella bronchiseptica, and Chlamydophila felis), and not generally recommended (Giardia and feline infectious peritonitis [FIP]). The following recommendations were adapted from the AAFP Panel Report.

VACCINATION PROTOCOLS FOR DOGS

A physical examination, fecal parasite screen, and vaccine needs assessment should be performed at least yearly for all dogs. The American Animal Hospital Association recently published the revised version of vaccination guidelines for dogs (Paul et al., 2006; http://www.aahanet.org/PublicDocuments/VaccineGuidelines06Revised.pdf) that also included recommendations for use of canine vaccines in shelters. These guidelines are an excellent source of information for veterinarians to use when individualizing a vaccination protocol for dogs. Different forms of vaccine antigens were divided into those that were considered core, noncore, and not recommended. For two products (Crotalus atrox toxoid and Porphyromonas spp.), the Task Force chose to take no position because of a lack of experience and paucity of field validation of efficacy. The following discussion was adapted from those guidelines.