Shelter animals require a diffeent approach when it comes to vaccination. If possible, it is best to try to get a complete
record of the animal's history from the adopting shelter.
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The principles involved in designing a vaccination program for the animal shelter are the same general principles behind any
disease prevention program. The difference is in the relative importance of various concepts as they pertain to the shelter
population and environment. Shelters take animals from a wide variety of sources, occasionally with a detailed medical history
but most often with little or no information. The risk of exposure to infectious disease is much higher in the shelter than
for the general population, and the subclinically infected or mildly afflicted animals pose the greatest danger, especially
to the young.
The principles for vaccination It is useful to divide vaccines into "core" and "non-core," where the latter are optional depending on the animal's home environment
and "lifestyle," e.g. hunting dog vs. lap dog. In most shelters, the "non-core" concept is not relevant. Core vaccines protect
against highly contagious, often endemic diseases with significant mortality, morbidity or economic consequences. The core
of a shelter vaccination program is likely to differ from one in private practice and among shelters. Shelter protocols may
vary according to differences in location, facilities, resources, average length of stay, and mission or philosophy, e.g.
limited admission vs. animal control. If vaccination for Microsporum canis effectively and economically prevented dermatophytosis,
for example, it might be routine in many shelters, but few practices.
In any case, risk and efficacy have to be weighed against expense. Shelters often have small budgets and no hope of recouping
costs from adopters. Some shelters use the intranasal vaccine against Bordetella in cats, but the cost per dose puts a premium
on determining the significance of the disease in that particular environment. Whereas having many animals from many places
in close proximity argues for a comprehensive vaccination program, economics is often a limiting factor. Another problem is
the lag between vaccine administration and, if all goes well, immunization. Waiting or quarantine periods are advisable if
not always feasible. Injectable vaccines may take over a week to induce immunity.
Table 1: Proposed Categorization of Infectious Diseases/ Vaccines for Animal Shelter Protocols
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For legal and public health reasons, vaccination against rabies is warranted before (or shortly after) adoption, even though
rabies exposure is highly unlikely in the shelter. It should arguably not be done until any waiting period for lost animals
is past or until ownership is signed over to the shelter, or when there is proof of current vaccination. An animal suspected
or known to have bitten someone cannot be vaccinated and requires close observation or testing. Animals with suspicious bite
wounds pose a dilemma. If previously vaccinated, they would be boostered; if not, vaccination will not protect them but may
slow the onset of the disease. Realistically, unknown animals with severe unexplained bite wounds are probably too great a
risk and require too much time and expense for a shelter to handle.
Providing protection Protection against canine and feline parvovirus (panleukopenia) is essential. Young animals are exposed to virus in the environment,
where it is very difficult to inactivate. Kittens and puppies should be vaccinated as early as 6 weeks of age, then every
two to three weeks until the age of 3 months in kittens and 4 months in pups. If we start at 6 or 7 weeks of age, I give the
first booster two weeks later. High-titer low-passage canine parvovirus vaccines should be used, and highly susceptible breeds
should be given boosters until they are more than 5 months of age. The protocol for canine distemper and adenovirus vaccination
follows that for parvovirus. If canine distemper is a known threat, the distemper/measles vaccine can be used in pups at 6
weeks of age. It should be given in the muscle. Adults, even with no vaccine history, do not need a three to four week booster
for these viruses.
Whether or not to include Leptospira in dog or puppy vaccines depends on the incidence of leptospirosis in the area, public
perceptions and concerns, the presence (or absence) of relevant serovars in the vaccine, and the possibility of adverse reactions
and a short duration of immunity. If used, adult dogs need a booster shot in three to four weeks. The significance of canine
coronavirus as a cause of clinical disease in shelters is unknown. It might be relevant in some multiple-dog environments,
where vaccination is recommended every six months, but it seems to cause only mild disease in young pups under certain conditions.
Intranasal vaccination against Bordetella bronchiseptica and canine parainfluenza virus in dogs is routine in a multiple-dog
setting, and can be given to 4-week-old pups. It does not protect against all causes of infectious tracheobronchitis, and
should be repeated at six-month intervals as long as there is a risk of exposure. In cats, more relevant than the intranasal
feline Bordetella vaccine is the topical bivalent vaccine against calicivirus and herpesvirus (rhinotracheitis), which is
administered in the eyes and nares. There is no advantage to including panleukopenia in the vaccine, and it has been implicated
in an outbreak of salmonellosis in kittens.
Routine in some shelters, but not others, topical vaccination against feline respiratory viruses should induce immunity in
as little as two to three days at the sites of viral attack. More data is needed on the efficacy of the vaccine in shelters,
but one study showed a significant decrease in the occurrence and severity of upper respiratory infection (URI). My sense
is that the incidence of URI is roughly the same since we started using the vaccine at the American Society for the Prevention
of Cruelty to Animals (ASPCA) two years ago, but there are fewer severe cases among vaccinates. For example, we have seen
fewer cats with caliciviral lingual ulceration. The apparent disease incidence may include many vaccine reactions, which can
occur days after inoculation and resemble mild URI.
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