Non-core vaccines are those which we as a profession have determined are not recommended for all dogs or cats. Vaccination,
in general, has the benefit of potentially lessening the prevalence or severity of disease, ensuring that patients are examined
on a regular basis, increasing practice revenue, and potentially saving clients money in the long-run. However vaccination
has also been associated with acute severe, life-threatening illness (anaphylaxis, respiratory distress), subacute illnesses
(IMHA), and potentially fatal long-term effects (vaccine-associated sarcomas). Short- and long-term efficacy of the non-core
vaccines are also commonly called into question. There is no question that many of the non-core vaccines are controversial;
this presentation will review the pros and cons for some of these vaccines based on the peer reviewed literature and the general
impression of specialists, and conclude with the speaker's personal views on each product.
FELINE INFECTIOUS PERITONITIS
The prevalence of feline enteric coronavirus varies from 15% in single-cat households to 80% of breeding cats. Cats in multicat
households, purebred cats, outdoor cats, and cats from shelters or humane societies have a higher rate of infection. The
majority of cats develop no overt clinical signs, although mild transient diarrhea may occur. The virus replicates within
the gastrointestinal tract epithelial cells and draining lymph nodes, and transient viremia may occur. Feline infectious
peritonitis develops following mutation in the viral genome; alteration of the 3C or 7B protein (at one of several possible
locations) allows the virus to lose its epitheliotropism, infect macrophages and monocytes, and disseminate throughout the
host. The host invariably succumbs to vasculitis or intraparenchymal granulomas. It appears that once the mutated virus
becomes systemically distributed it is no longer shed in the feces the way that non-mutated enteric coronavirus is; therefore
FIP is not considered a contagious disease.
Pros for vaccination:
1. FIP is invariably fatal—any chance at preventing development of disease is worthwhile.
2. FIP is most devastating in areas of high cat density; therefore vaccination will hopefully confer some herd immunity
to these populations.
Cons against vaccination:
1. Once cats are infected with coronavirus (usually at a very young age) the FIP vaccine will not prevent mutations or
dissemination of pathogenic FIP virus.
2. The FIP vaccine does not reliably cause a decrease in the incidence of FIP.
3. Preventative strategies in herd health situations are much more efficacious than the vaccine.
4. The vaccine induces antibodies that are indistinguishable from anti-enteric coronavirus antibodies; therefore screening
and removal of infected individuals is impossible after vaccination.
5. Some studies have shown that vaccines could be associated with antibody-dependent enhancement of disease (although
this is uncertain, as it was shown in experimental animals with viral strains of increased virulence).
—Two populations should be considered for this vaccine. Single cat/low-number multicat households (i.e. <5 cats) are at inherently
lower risk for FIP outbreaks. Most of these cats are already infected with feline enteric coronavirus, so vaccination is
of questionable benefit. In cattery and shelter situations good husbandry practices and/or screening and elimination of coronavirus
carriers is known to be far more effective in preventing disease than the FIP vaccine. The American Association of Feline
Practitioners does not recommend use of this vaccine, as it has not been shown to produce clinically relevant protection.