Objective—To develop a spatial epidemic model to
simulate intraherd and interherd transmission of footand-
mouth disease (FMD) virus.
Sample Population—2,238 herds, representing
beef, dairy, swine, goats, and sheep, and 5 sale yards
located in Fresno, Kings, and Tulare counties of
Procedure—Using Monte-Carlo simulations, a spatial
stochastic epidemic simulation model was developed
to identify new herds that would acquire FMD following
random selection of an index herd and to assess
progression of an epidemic after implementation of
mandatory control strategies.
Results—The model included species-specific transition
periods for FMD infection, locations of herds,
rates of direct and indirect contacts among herds, and
probability distributions derived from expert opinions
on probabilities of transmission by direct and indirect
contact, as well as reduction in contact following
implementation of restrictions on movements in designated
infected areas and surveillance zones.
Models of supplemental control programs included
slaughter of all animals within a specified distance of
infected herds, slaughter of only high-risk animals
identified by use of a model simulation, and vaccination
of all animals within a 5- to 50-km radius of infected
Conclusions and Clinical Relevance—The FMD
model represents a tool for use in planning biosecurity
and emergency-response programs and in comparing
potential benefits of various strategies for control
and eradication of FMD appropriate for specific populations.
(Am J Vet Res 2003;64:195–204)
Objective—To assess estimated effectiveness of
control and eradication procedures for foot-andmouth
disease (FMD) in a region of California.
Sample Population—2,238 herds and 5 sale yards in
Fresno, Kings, and Tulare counties of California.
Procedure—A spatial stochastic model was used to
simulate hypothetical epidemics of FMD for specified
control scenarios that included a baseline eradication
strategy mandated by USDA and supplemental control
strategies of slaughter or vaccination of all animals within
a specified distance of infected herds, slaughter of
only high-risk animals identified by use of a model simulation,
and expansion of infected and surveillance zones.
Results—Median number of herds affected varied
from 1 to 385 (17% of all herds), depending on type
of index herd and delay in diagnosis of FMD.
Percentage of herds infected decreased from that of
the baseline eradication strategy by expanding the
designated infected area from 10 to 20 km (48%),
vaccinating within a 50-km radius of an infected herd
(41%), slaughtering the 10 highest-risk herds for each
infected herd (39%), and slaughtering all animals
within 5 km of an infected herd (24%).
Conclusions and Clinical Relevance—Results for the
model provided a means of assessing the relative merits
of potential strategies for control and eradication of
FMD should it enter the US livestock population. For the
study region, preemptive slaughter of highest-risk herds
and vaccination of all animals within a specified distance
of an infected herd consistently decreased size and
duration of an epidemic, compared with the baseline
eradication strategy. (Am J Vet Res 2003;64:205–210)
Objective—To assess relative costs and benefits of
vaccination and preemptive herd slaughter to control
transmission of foot-and-mouth disease (FMD) virus
Sample Population—2,238 herds and 5 sale yards
located in Fresno, Kings, and Tulare counties of
Procedure—Direct costs associated with indemnity,
slaughter, cleaning and disinfecting livestock premises,
and vaccination were compared for various eradication
strategies. Additional cost, total program cost,
net benefit, and benefit-cost value (B/C) for each supplemental
strategy were estimated, based in part on
results of published model simulations for FMD.
Sensitivity analyses were conducted.
Results—Mean herd indemnity payments were estimated
to be $2.6 million and $110,359 for dairy and
nondairy herds, respectively. Cost to clean and disinfect
livestock premises ranged from $18,062 to
$60,205. Mean vaccination cost was $2,960/herd.
Total eradication cost ranged from $61 million to $551
million. All supplemental strategies involving use of
vaccination were economically efficient (B/C range,
5.0 to 10.1) and feasible, whereas supplemental
strategies involving use of slaughter programs were
not economically efficient (B-C, 0.05 to 0.8) or feasible.
Conclusions and Clinical Relevance—Vaccination
with a highly efficacious vaccine may be a cost-effective
strategy for control of FMD if vaccinated animals
are not subsequently slaughtered and there is no
future adverse economic impact, such as trade
restrictions. Although less preferable than the baseline
eradication program, selective slaughter of highest-risk herds was preferable to other preemptive
slaughter strategies. However, indirect costs can be
expected to contribute substantially more than direct
costs to the total cost of eradication programs. (Am J Vet Res 2003;64:805–812)
Objective—To estimate direct and indirect contact
rates on livestock facilities and distance traveled
between herd contacts.
Sample Population—320 beef, dairy, goat, sheep,
and swine herds, 7 artificial insemination technicians,
6 hoof trimmers, 15 veterinarians, 4 sales yard owners,
and 7 managers of livestock-related companies
within a 3-county region of California.
Procedure—A questionnaire was mailed to livestock
producers, and personal and telephone interviews
were conducted with individuals.
Results—Mean monthly direct contact rates were
2.6, 1.6, and 2.0 for dairies with < 1,000, 1,000 to
1,999, and ≥ 2,000 cattle, respectively. Mean indirect
contact rates on dairies ranged from 234 to 743 contacts/
mo and increased by 1 contact/mo as herd size
increased by 4.3. Mean direct monthly contact rate
for beef herds was 0.4. Distance traveled by personnel
and vehicles during a 3-day period ranged from
58.4 to 210.4 km. Of livestock arriving at sales yards,
7% (500/7,072) came from ≥ 60 km away, and of
those sold, 32% (1,180/3,721) were destined for a
location ≥ 60 km away. Fifty-five percent (16/29) of
owners of large beef herds observed deer or elk within
150 m of livestock at least once per month.
Conclusions and Clinical Relevance—Direct and
indirect contacts occur on livestock facilities located
over a wide geographic area and at a higher frequency
on larger facilities. Knowledge of contact rates may
be useful for planning biosecurity programs at the
herd, state, and national levels and for modeling
transmission potential for foot-and-mouth disease
virus. (Am J Vet Res 2001;62:1121–1129)
Objective—To characterize husbandry practices that could affect the risks of foreign animal disease in miniature swine.
Study Population—106 owners of miniature swine.
Procedures—An online survey of owners of miniature swine was conducted to obtain information about miniature pig and owner demographics; pig husbandry; movements of pigs; and pig contacts with humans, other miniature swine, and livestock.
Results—12 states, 106 premises, and 317 miniature swine were represented in the survey. More than a third (35%) of miniature swine owners also owned other livestock species. Regular contact with livestock species at other premises was reported by 13% of owners. More than a third of owners visited shows or fairs (39%) and club or association events (37%) where miniature swine were present. More than 40% of owners fed food waste to miniature swine. Approximately half (48%) of the veterinarians providing health care for miniature swine were in mixed-animal practice.
Conclusions and Clinical Relevance—Results of this study indicated that miniature swine kept as pets can be exposed, directly and indirectly, to feed and other livestock, potentially introducing, establishing, or spreading a foreign animal disease such as foot-and-mouth disease. In addition, the veterinary services and carcass disposal methods used by miniature swine owners may reduce the likelihood of sick or dead pigs undergoing ante- or postmortem examination by a veterinarian.
Animals—46 AED-naïve dogs with naturally occurring epilepsy.
Procedures—Study inclusion was based on age, history, findings on physical and neurologic examinations, and clinicopathologic test results. For either phenobarbital treatment (21 dogs) or bromide treatment (25), a 7-day loading dose period was initiated along with a maintenance dose, which was adjusted on the basis of monthly monitoring. Efficacy and safety outcomes were compared between times (baseline and study end [generally 6 months]) and between drugs.
Results—Phenobarbital treatment resulted in eradication of seizures (17/20 [85%]) significantly more often than did bromide (12/23 [52%]); phenobarbital treatment also resulted in a greater percentage decrease in seizure duration (88 ± 34%), compared with bromide (49 ± 75%). Seizure activity worsened in 3 bromide-treated dogs only. In dogs with seizure eradication, mean ± SD serum phenobarbital concentration was 25 ± 6 μg/mL (phenobarbital dosage, 4.1 ± 1.1 mg/kg [1.9 ± 0.5 mg/lb], PO, q 12 h) and mean serum bromide concentration was 1.8 ± 0.6 mg/mL (bromide dosage, 31 ± 11 mg/kg [14 ± 5 mg/lb], PO, q 12 h). Ataxia, lethargy, and polydipsia were greater at 1 month for phenobarbital-treated dogs; vomiting was greater for bromide-treated dogs at 1 month and study end.
Conclusions and Clinical Relevance—Both phenobarbital and bromide were reasonable first-choice AEDs for dogs, but phenobarbital was more effective and better tolerated during the first 6 months of treatment.
Objective—To determine the lowest of 5 doses of cosyntropin (1.0, 0.5, 0.1, 0.05, or 0.01 μg/kg) administered IV that stimulates maximal cortisol secretion in clinically normal dogs.
Animals—10 clinically normal dogs.
Procedures—5 dose-response experiments were performed in each of the dogs. Each dog received 5 doses of cosyntropin (1.0, 0.5, 0.1, 0.05, and 0.01 μg/kg) IV in random order (2-week interval between each dose). Serum samples for determination of cortisol concentrations were obtained before (baseline) and at 10, 20, 30, 40, 50, 60, 120, and 240 minutes after cosyntropin administration.
Results—Compared with baseline values, mean serum cortisol concentration in the study dogs increased significantly after administration of each of the 5 cosyntropin doses. Mean peak serum cortisol concentration was significantly lower after administration of 0.01, 0.05, and 0.1 μg of cosyntropin/kg, compared with findings after administration of 0.5 and 1.0 μg of cosyntropin/kg. After administration of 0.5 and 1.0 μg of cosyntropin/kg, mean peak serum cortisol concentration did not differ significantly; higher doses of cosyntropin resulted in more sustained increases in serum cortisol concentration, and peak response developed after a longer interval.
Conclusions and Clinical Relevance—Administration of cosyntropin IV at a dose of 0.5 μg/kg induced maximal cortisol secretion in healthy dogs. Serum cortisol concentration was reliably increased in all dogs after the administration of each of the 5 doses of cosyntropin. These data should be useful in subsequent studies to evaluate the hypothalamic-pituitary-adrenal axis in healthy and critically ill dogs.
Objective—To determine the effect of treatment approach on outcome and the appropriateness of initial empirical antimicrobial treatment in dogs with pyothorax.
Design—Retrospective case series.
Animals—46 dogs with pyothorax confirmed by either (n = 15) or both (31) of the following: intracellular bacteria in pleural fluid or tissue (41) and bacteria recovered via culture of pleural fluid (36).
Procedures—Medical records of dogs treated for pyothorax from 1983 through 2001 were reviewed. Data on signalment, history, clinical signs, and treatment and results of diagnostic imaging and cytologic and microbiological evaluations were obtained. Follow-up was performed via reexamination (n = 15) and contact with referring veterinarians (26) and owners (24).
Results—46 dogs were treated with at least 1 antimicrobial and thoracocentesis (n = 7; noninvasive group), a thoracostomy tube (26; invasive group) with or without pleural lavage and heparin, or a thoracotomy (13; surgical group) and thoracostomy tube with or without pleural lavage and heparin. Pyothorax recurred in 7 dogs, and 5 of the 7 died or were euthanatized. In the respective groups, the short-term survival rate was 29%, 77%, and 92% and the long-term survival rate was 29%, 71%, and 70%. Pleural lavage and heparin treatment increased the likelihood of short- and long-term survival. Results of antimicrobial susceptibility testing suggested empirical antimicrobial selection was associated with a 35% risk of inefficacy.
Conclusions and Clinical Relevance—In the dogs with pyothorax in this study, favorable treatment effects were achieved with surgery (for short-term survival) and pleural lavage and heparin treatment (for short- and long-term survival). Findings failed to support the hypothesis that invasive (surgical) versus noninvasive treatment of pyothorax in dogs leads to a better long-term outcome.
Objective—To evaluate differences in bacterial numbers,
identity, and susceptibility in samples obtained
from the tympanic cavity on entry (preflush) and after
evacuation and lavage (postflush) and assess perioperative
and empiric antimicrobial selection in dogs
that underwent total ear canal ablation (TECA) with
lateral bulla osteotomy (LBO) or reoperation LBO.
Design—Prospective clinical study.
Procedure—TECA with LBO or reoperation LBO was
performed on 47 ears. Pre- and postflush aerobic and
anaerobic samples were obtained from the tympanic
cavity. Isolates and antimicrobial susceptibility patterns
Results—Different isolates (31/44 [70%] ears) and susceptibility
patterns of isolate pairs (6/44 [14%] ears)
were detected in pre- and postflush samples from
84% of ears. Evacuation and lavage of the tympanic
cavity decreased the number of bacterial isolates by
33%. In 26% of ears, bacteria were isolated from postflush
samples but not preflush samples. Only 26% of
isolates tested were susceptible to cefazolin. At least 1
isolate from 53% of dogs that received empirically chosen
antimicrobials postoperatively was resistant to the
selected drugs. Anaerobic bacteria were recovered
from 6 ears.
Conclusions and Clinical Relevance—Accurate
microbiologic assessment of the tympanic cavity
should be the basis for selection of antimicrobials in
dogs undergoing TECA with LBO. Bacteria remain in
the tympanic cavity after evacuation and lavage.
Cefazolin was a poor choice for dogs that underwent
TECA with LBO, as judged on the basis of culture and
susceptibility testing results. (J Am Vet Med Assoc 2005;227:748–755)