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OBJECTIVE: To determine whether West Nile virus (WNV) disease hyperendemic foci (hot spots) exist within the horse population in Texas and, if detected, to identify the locations. SAMPLE POPULATION: Reports of 1,907 horses with WNV disease in Texas from 2002 to 2004. Procedures: Case data with spatial information from WNV epidemics occurring in 2002 (1,377 horses), 2003 (396 horses), and 2004 (134 horses) were analyzed by use of the spatial scan statistic (Poisson model) and kriging of empirical Bayes smoothed county attack rates to determine locations of horses with WNV disease in which affected horses were consistently (in each of the 3 study years) clustered (hyperendemic foci, or hot spots). RESULTS: 2 WNV hot spots in Texas, an area in northwestern Texas and an area in eastern Texas, were identified with the scan statistic. Risk maps of the WNV epidemics were qualitatively consistent with the hot spots identified. Conclusions and CLINICAL RELEVANCE: WNV hot spots existed within the horse population in Texas (2002 to 2004). Knowledge of disease hot spots allows disease control and prevention programs to be made more efficient through targeted surveillance and education.

Wittich CAWard MPFosgate GTSrinivasan R
Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843-4458, USA.

A definitive cure for type 1 diabetes is currently being pursued with enormous effort by the scientific community. Different strategies are followed to restore physiologic production of insulin in diabetic patients. Restoration of self-tolerance remains the milestone that must be reached in order to move a step further and recover a cell source capable of independent and functional insulin production. Multiple strategies aimed at modulation of both central and peripheral immunity must be considered. Promising results now show that the immune system can be modulated in a way that acquisition of a “diabetes-suppressive” phenotype is possible. Once self-tolerance is achieved, reversal of the disease may be obtained by simply allowing physiologic rescue and/or regeneration of the β cells to take place. Given that these outcomes have already been confirmed in humans, refinement of existing protocols along with novel methods adapted to T1DM reversal will allow translation into clinical trials.

Lorenzo Pasqualia　Nick Giannoukakisa　Massimo TruccoaEmail:mnt@pitt.edu
[a]Division of Immunogenetics, Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213, USA;[b]Department of Pediatrics, University of Genoa, Institute G. Gaslini, 16174 Genoa, Italy;[c]Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213, USA

OBJECTIVE: To define the reference range for laminar blood flow (BF) and vascular permeability (VPM) in horses without laminitis by use of dynamic contrast-enhanced computed tomography (CT). ANIMALS: 9 adult horses that were not lame and had no abnormalities of the laminae or phalanges detectable via radiographic examination. PROCEDURES: Each horse was anesthetized by use of a routine protocol. Horses were placed in right or left lateral recumbency with the dependent forelimb in the CT gantry; only 1 limb of each horse was scanned. Serial 10-mm collimated transverse CT images were acquired at the same location every other second for 90 seconds during infusion of ionic, iodinated contrast medium. Custom software was used to estimate BF, VPM, and fractional vascular volume (FVV) in the dorsal, dorsomedial, and dorsolateral laminar regions. RESULTS: Among the 9 horses’ forelimbs, mean +/- SD dorsal laminar BF was 0.43 +/- 0.21 mL*min(1)*mL(1). Mean dorsomedial and dorsolateral laminar BFs were 0.26 +/- 0.16 mL*min(1)*mL(1) and 0.24 +/- 0.16 mL*min(1)*mL(1), respectively. Mean dorsal laminar VPM was 0.09 +/- 0.03 mL*min(1)*mL(1). Mean dorsomedial and dorsolateral laminar VPMs were 0.16 +/- 0.06 mL*min(1)*mL(1) and 0.12 +/- 0.06 mL*min(1)*mL(1), respectively. Mean dorsal laminar FVV was 0.63 +/- 0.20 and dorsomedial and dorsolateral laminar FVV were 0.37 +/- 0.14 and 0.34 +/- 0.17, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: In horses, laminar BF, VPM, and FVV can be non-invasively measured by use of dynamic contrast-enhanced CT.

Kruger EFPuchalski SMPollard REGaluppo LDHornof WJWisner ER
Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.

OBJECTIVE: To evaluate correlations among measurements on radiographic and computed tomography (CT) images with articular cartilage microdamage in lax hip joints of dogs. ANIMALS: 12 adult mixed-breed hounds. PROCEDURES: Pelvic CT and radiography were performed. Hip joints were harvested following euthanasia. Orthopedic Foundation for Animals (OFA) and PennHIP radiograph reports were obtained. Norberg angle (NA) and radiographic percentage femoral head coverage (RPC) were determined. Center-edge angle (CEA), horizontal toit externe angle (HTEA), ventral acetabular sector angle (VASA), dorsal acetabular sector angle (DASA), horizontal acetabular sector angle (HASA), acetabular index (AI), and CT percentage femoral head coverage (CPC) were measured on 2-dimensional CT images. Femoral head-acetabular shelf percentage was measured on sagittal 3-dimensional CT (SCT) and transverse 3-dimensional CT (TCT) images. Light microscopy was used to score joint cartilage. Relationships of OFA confirmation and PennHIP osteoarthritis scores with radiography, CT, and cartilage variables and relationships of cartilage scores with radiography and CT measurements were evaluated with Spearman rank correlations. Pearson correlation was used for relationships of distraction index (DI) with radiography, CT, and cartilage variables. RESULTS: Significant relationships included PennHIP osteoarthritis score with cartilage score, CEA, HTEA, DASA, AI, CPC, and TCT; OFA confirmation score with cartilage score, NA, RPC, CEA, HTEA, DASA, AI, CPC, and TCT; cartilage score with NA, RPC, CEA, HTEA, DASA, HASA, AI, and TCT; and DI with cartilage score, CEA, HTEA, DASA, HASA, AI, and CPC. CONCLUSIONS AND CLINICAL RELEVANCE: CT appeared to be a valuable imaging modality for predicting cartilage microdamage in canine hip joints.

Lopez MJLewis BPSwaab MEMarkel MD
School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA 70803, USA.

OBJECTIVE: To determine the effect of naturally acquired heartworm (Dirofilaria immitis) infection on myocardial fluid balance as indicated by myocardial water content and the dynamics of transepicardial fluid flow. ANIMALS: 7 dogs infected with adult heartworms and 8 dogs free of heartworm infection. PROCEDURES: Infected dogs had heartworms in the right ventricle, pulmonary artery, or both but no evidence of cardiovascular disease on physical examination. A hemispheric capsule was attached to the epicardial surface of all dogs for determination of transepicardial fluid dynamics and permeability of the epicardium to water and protein. Myocardial water content and hydroxyproline content were assessed at necropsy. RESULTS: Myocardial water content was significantly lower in heartworm-infected dogs. No differences in myocardial hydroxyproline content, transepicardial fluid flow, or epicardial water or protein permeability were detected. Conclusions and CLINICAL RELEVANCE: Heartworm infection significantly altered myocardial fluid balance in dogs, possibly because of a change in the myocardial interstitial pressure-volume relationship. These changes may be associated with increased vulnerability to cardiovascular stressors in heartworm-infected dogs.

Stewart RHUray KCox CSLaine GA
Michael E. DeBakey Institute, Texas A&M University, College Station, TX 77843, USA.

OBJECTIVE: To compare isolated limb retrograde venous injection (ILRVI) and isolated limb infusion (ILI) for delivery of amikacin to the synovial fluid of the distal interphalangeal and metacarpophalangeal joints and to evaluate the efficacy of use of an Esmarch tourniquet in standing horses. ANIMALS: 6 healthy adult horses. PROCEDURES: Horses were randomly assigned in a crossover design. In ILRVI, the injection consisted of 1 g of amikacin diluted to a total volume of 60 mL administered during a 3-minute period. In ILI, the infusion consisted of 1 g of amikacin diluted to 40 mL administered during a 3-minute period followed by administration of boluses of diluent (82 mL total) to maintain vascular pressure. During ILI, the infusate and blood were circulated from the venous to the arterial circulation in 5-mL aliquots. Synovial fluid and serum samples were obtained to determine maximum amikacin concentrations and tourniquet leakage, respectively. RESULTS: Both techniques yielded synovial concentrations of amikacin>10 times the minimum inhibitory concentration (MIC) for 90% of isolates (80 microg/mL) and>10 times the MIC breakpoint (160 microg/mL) of amikacin-susceptible bacteria reported to cause septic arthritis in horses. These values were attained for both joints for both techniques. Esmarch tourniquets prevented detectable loss of amikacin to the systemic circulation for both techniques. CONCLUSIONS AND CLINICAL RELEVANCE: Both techniques reliably achieved synovial fluid concentrations of amikacin consistent with concentration-dependent killing for bacteria commonly encountered in horses with septic arthritis. Esmarch tourniquets were effective for both delivery techniques in standing horses.

Errico JATrumble TNBueno ACDavis JLBrown MP
Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL 32610, USA.