Objective—To develop partial budgets of the economic
costs of 2 test strategies for screening cattle for persistent
infection with bovine viral diarrhea virus (BVDV).
Design—Partial budget analysis.
Animals—938 calves arriving at 2 stocker operations.
Procedure—Calves were tested to determine prevalence
of persistent BVDV infection. Test strategies that
were evaluated included a single-test strategy consisting
of immunohistochemical staining of skin biopsy
specimens from all animals and a 2-test strategy consisting
of polymerase chain reaction (PCR) assaying of
pooled blood samples followed by immunohistochemical
staining of skin biopsy specimens from animals in
pools for which assay results were positive. Breakeven
costs (ie, cost of persistent BVDV infection per
animal necessary to justify whole-herd diagnostic testing)
associated with each test strategy were calculated
as a function of disease prevalence and test cost.
Results—Apparent prevalence of persistent BVDV
infection was 0.32%. Sensitivity and specificity of the
PCR assay for pooled samples were 100% and
89.7%, respectively. Regardless of the prevalence of
persistent BVDV infection, the break-even cost for the
2-test strategy was lower than the break-even cost for
the single-test strategy. However, the economic
advantage was greatest when prevalence was low.
Conclusions and Clinical Relevance—Results suggest
that using a 2-test strategy to screen cattle for persistent
BVDV infection, whereby the first test involves
PCR assaying of pooled samples and the second
involves immunohistochemical testing only of those animals
represented in pooled samples with positive assay
results, will reduce the cost of screening incoming feedlot
cattle, compared with immunohistochemical testing
of all animals. (J Am Vet Med Assoc 2005;226:249–254)
Objective—To evaluate a technique for minimally invasive excisional brain biopsy and intracranial brachytherapy catheter placement in dogs.
Animals—5 healthy adult female dogs.
Procedures—Computed tomographic guidance was used to plan a biopsy trajectory to a selected area of brain with reference to a localizer grid. The procedure was performed through a 1-cm skin incision and 6-mm burr hole by use of a 9-gauge biopsy device. Five cylindrical samples (3 to 4 mm in diameter and 7 to 12 mm in length) were removed over 5 cycles of the vacuum-assisted tissue excision system, leaving approximately a 2-cm3 resection cavity. A balloon-tipped intracranial brachytherapy catheter was placed through the burr hole into the resection cavity, expanded with saline (0.9% NaCl) solution, and explanted 7 days later.
Results—4 of 5 dogs survived the procedure. The fifth died because of iatrogenic brain damage. Neurologic deficits were unilateral and focal. Twenty-four hours after surgery, all surviving dogs were ambulatory, 2 dogs exhibited ipsiversive circling, 4 had contralateral proprioceptive deficits, 3 had contralateral menace response deficits, 2 had a reduced contralateral response to noxious nasal stimulation, and 1 had dull mentation with intermittent horizontal nystagmus and ventrolateral strabismus. Neurologic status improved throughout the study period. Histologic quality of biopsy specimens was excellent.
Conclusions and Clinical Relevance—This technique enabled histologic diagnosis from high-quality biopsy specimens obtained through a minimally invasive technique and has potential applications for multimodal treatment of deep brain tumors in dogs.
Objective—To develop and assess the short-term feasibility, maintenance, and complications associated with percutaneous endoscopic gastrostomy (PEG) tube placement in standing horses.
Animals—6 adult horses.
Procedures—Feasibility of the technique was evaluated in 2 horses. In each of 4 other horses, a PEG tube was maintained for 14 days and used to provide fluid requirements during the latter 7 days, before removal. Following air inflation of the stomach, each PEG tube was placed via a left intercostal approach; proper tube location was ascertained by percutaneous ultrasonography and gastroscopy. The horses underwent physical examinations, CBCs, and peritoneal fluid analyses before and at intervals after tube placement. Seven days after tube removal, horses were euthanized and necropsied.
Results—Placement of a PEG tube was feasible in all 6 horses. The 4 horses assessed long term tolerated water administration through the PEG tube and remained clinically stable throughout the 21-day experiment. However, during the period PEG tubes were in place, significant increases in some peritoneal and hematologic variables were detected. Postmortem evaluation revealed localized peritonitis in 1 horse and body wall inflammation along the PEG tube tracks in 3 additional horses.
Conclusions and Clinical Relevance—Placement and maintenance of a PEG tube were tolerated well by the study horses, although peritoneal and systemic inflammation were detectable. Fluid requirements were adequately met with this technique, which could provide an alternative method for managing chronically dysphagic horses. Nevertheless, further research is warranted to evaluate the feasibility of enteral feeding by use of this approach in horses.
Objective—To evaluate concordance among veterinary
pathologists in the assessment of histologic findings
in the pars intermedia of pituitary gland sections
from aged horses with mild signs suggestive of pituitary
pars intermedia dysfunction (PPID).
Sample Population—10 pituitary glands from aged
Procedure—7 pathologists were provided with signalment,
clinical signs, and a single H&E-stained pituitary
gland section from 10 aged horses with mild
signs suggestive of PPID. Pathologists described histologic
findings for each section and stated whether
findings were consistent with PPID. Agreement
among pathologists and with antemortem diagnostic
test results was calculated.
Results—Overall, only fair agreement was found
among the pathologists as to which horses had histologic
findings consistent with disease (mean ± SE
kappa value, 0.34 ± 0.069). Interpretation of individual
sections varied, with minimal agreement (4 or 5/7
pathologists) for 5 of 10 sections evaluated.
Postmortem assessment was in agreement with an
antemortem endocrine diagnostic test result 79% of
Conclusions and Clinical Relevance—Validation of
antemortem diagnostic testing for PPID in horses
often relies on the results of postmortem histologic
evaluation. The lack of consensus in histologic interpretation
of pituitary glands from aged horses with
mild clinical signs in our study indicates that postmortem
histologic evaluation of pituitary glands is an
inappropriate standard in validation of antemortem
diagnostic tests for detection of early PPID. Caution
should be used when interpreting diagnostic test
results in horses in which early PPID is suspected.
(Am J Vet Res 2005;66:2055–2059)