Objective—To assess spatial and temporal patterns
of seroprevalence among dogs in California to the
causative agent of granulocytic ehrlichiosis (GE).
Sample Population—Sera of 1,082 clinically normal
dogs from 54 of 59 counties in California in 1997 to
Procedure—Serum-specific IgG reactivity to
Ehrlichia equi was assessed by use of an immunofluorescent
antibody assay, using E equi-infected horse
neutrophils as substrate. Data were analyzed, using a
geographic information system. Spatial analysis of
seroprevalence included first order Bayesian analysis
of seroprevalence and second order analysis of clustering
by K-function and Cuzick-Edwards tests.
Monthly seroprevalence among dogs was examined
by use of regression on monthly densities of Ixodes
pacificus adults and nymphs .
Results—Seroprevalence among dogs to E equi was
8.68%. Data were seasonally bimodal with highest
prevalence in winter (when adult ticks were abundant)
and a secondary peak in late spring (corresponding to
nymphal ticks). Humboldt County had the highest seroprevalence
(47.3%), and other northern coast range
counties had seroprevalence from 15 to 30%.
Conclusion and Clinical Relevance—The patchy
distribution of exposure to Ehrlichia organisms is a
subset of the distribution of the tick vector. This may
reflect enzootic cycles or climatic or historical factors
that limited the range of the disease. Dogs, horses,
and humans from north coast range counties in
California are at increased risk of GE. These data provide
a background for assessing risk of infection in
horses and dogs, depending on geographic location.
Dogs may be sentinels for assessing risk of GE in
humans. (Am J Vet Res 2001;62:1599–1605)
Objective—To evaluate 2 county trap-neuter-return
(TNR) programs for feral cat population management
via mathematical modeling.
Design—Theoretical population model.
Animals—Feral cats assessed from 1992 to 2003 in
San Diego County, California (n = 14,452), and from
1998 to 2004 in Alachua County, Florida (11,822).
Procedure—Data were analyzed with a mathematical
Ricker model to describe population dynamics of the
feral cats and modifications to the dynamics that
occurred as a result of the TNR programs.
Results—In both counties, results of analyses did not
indicate a consistent reduction in per capita growth,
the population multiplier, or the proportion of female
cats that were pregnant.
Conclusions and Clinical Relevance—Success of
feral cat management programs that use TNR can be
monitored with an easily collected set of data and statistical
analyses facilitated by population modeling
techniques. Results may be used to suggest possible
future monitoring and modification of TNR programs,
which could result in greater success controlling and
reducing feral cat populations. ( J Am Vet Med Assoc