Objective: To develop a better system for classification of herd infection status for paratuberculosis (Johne's disease [JD]) in US cattle herds on the basis of the risk of potential transmission of Mycobacterium avium subsp paratubeculosis. Sample: Simulated data for herd size and within-herd prevalence; sensitivity and specificity for test methods obtained from consensus-based estimates. Procedures: Interrelationships among variables influencing interpretation and classification of herd infection status for JD were evaluated by use of simulated data for various herd sizes, true within-herd prevalences, and sampling and testing methods. The probability of finding ≥ 1 infected animal in herds was estimated for various testing methods and sample sizes by use of hypergeometric random sampling. Results: 2 main components were required for the new herd JD classification system: the probability of detection of infection determined on the basis of test results from a sample of animals and the maximum detected number of animals with positive test results. Tables were constructed of the estimated probability of detection of infection, and the maximum number of cattle with positive test results or fecal pools with positive culture results with 95% confidence for classification of herd JD infection status were plotted. Herd risk for JD was categorized on the basis of 95% confidence that the true within-herd prevalence was ≤ 15%, ≤ 10%, ≤ 5%, or ≤ 2%. Conclusions and Clinical Relevance: Analysis of the findings indicated that a scientifically rigorous and transparent herd classification system for JD in cattle is feasible.

Objective-To objectively describe morphometric features of the craniocervical junction region of Cavalier King Charles Spaniels (CKCSs) and non-CKCS dogs with suspected Chiari-like malformation (CLM) and identify associations between these features and the presence of other malformations in this region. Animals-216 CKCSs and 58 non-CKCS dogs. Procedures-Magnetic resonance and computed tomographic images of the head and craniocervical junction region of patients evaluated because of suspected CLM were assessed for cerebellar compression (CC), ventral spinal cord compression at the C1-C2 articulation (medullary kinking), and dorsal spinal cord compression at the C1-C2 articulation (dorsal compression). A compression index was calculated for each of these 3 locations in each dog. Multiple logistic regression analysis was performed to determine whether breed (CKCS vs non-CKCS) and compression index values were associated with the presence of other craniocervical junction abnormalities. Results-All 274 dogs had CC; medullary kinking was identified in 187 (68.2%) and dorsal compression was identified in 104 (38.0%). Atlantooccipital overlapping (AOO) was identified in 76 (27.7%) dogs. Breed of dog (CKCS vs non-CKCS) and value of CC index were the only significant predictors of AOO. The CKCSs had an almost 5-fold decrease in risk of AOO, compared with the non-CKCS dogs, and the risk of AOO nearly doubled for every 10% increase in CC index. Conclusions and Clinical Relevance-The anatomic abnormality responsible for CC was AOO in a substantial percentage of dogs suspected to have CLM. The CC index value may be used to help differentiate subtypes of craniocervical junction abnormalities in dogs.

Objective: To determine the expression and distribution of a disintegrin and metalloproteinase with thrombospondin motifs-4 (ADAMTS-4), its substrates aggrecan and versican, and their binding partner hyaluronan in laminae of healthy horses. Sample: Laminae from the forelimb hooves of 8 healthy horses. Procedures: Real-time quantitative PCR assay was used for gene expression analysis. Hyaluronidase, chondroitinase, and keratanase digestion of lamina extracts combined with SDS-PAGE and western blotting were used for protein and proteoglycan analysis. Immunofluorescent and immunohistochemical staining of tissue sections were used for protein and hyaluronan localization. Results: Genes encoding ADAMTS-4, aggrecan, versican, and hyaluronan synthase II were expressed in laminae. The ADAMTS-4 was predominantly evident as a 51-kDa protein bearing a catalytic site neoepitope indicative of active enzyme and in situ activity, which was confirmed by the presence of aggrecan and versican fragments bearing ADAMTS-4 cleavage neoepitopes in laminar protein extracts. Aggrecan, versican, and hyaluronan were localized to basal epithelial cells within the secondary epidermal laminae. The ADAMTS-4 localized to these cells but was also present in some cells in the dermal laminae. Conclusions and Clinical Relevance: Within digital laminae, versican exclusively and aggrecan primarily localized within basal epithelial cells and both were constitutively cleaved by ADAMTS-4, which therefore contributed to their turnover. On the basis of known properties of these proteoglycans, it is possible that they can protect the basal epithelial cells of horses from biomechanical and concussive stress.

Objective: To determine the tissue depletion profile of tulathromycin and determine an appropriate slaughter withdrawal interval in meat goats after multiple SC injections of the drug. Animals: 16 healthy Boer goats. Procedures: All goats were administered tulathromycin (2.5 mg/kg, SC) twice, with a 7-day interval between doses. Blood samples were collected throughout the study, and goats were euthanized at 2, 5, 10, and 20 days after the second tulathromycin dose. Lung, liver, kidney, fat, and muscle tissues were collected. Concentrations of tulathromycin in plasma and the hydrolytic tulathromycin fragment CP-60,300 in tissue samples were determined with ultrahigh-pressure liquid chromatography–tandem mass spectrometry. Results: The plasma profile of tulathromycin was biphasic. Absorption was very rapid, with maximum drug concentrations (1.00 ± 0.42 μg/mL and 2.09 ± 1.77 μg/mL following the first and second doses, respectively) detected within approximately 1 hour after injection. Plasma terminal elimination half-life of tulathromycin was 61.4 ± 14.1 hours after the second dose. Half-lives in tissue ranged from 2.4 days for muscle to 9.0 days for lung tissue; kidney tissue was used to determine the withdrawal interval for tulathromycin in goats because it is considered an edible tissue. Conclusions and Clinical Relevance: On the basis of the tissue tolerance limit in cattle of 5 ppm (μg/g), the calculated withdrawal interval for tulathromycin would be 19 days following SC administration in goats. On the basis of the more stringent guidelines recommended by the FDA, the calculated meat withdrawal interval following tulathromycin administration in goats was 34 days.

Objective: To evaluate 2 plate designs for pancarpal arthrodesis and their effects on load transfer to the respective bones as well as to develop a computational model with directed input from the biomechanical testing of the 2 constructs. Sample: Both forelimbs from the cadaver of an adult castrated male Golden Retriever. Procedures: CT imaging was performed on the forelimb pair. Each forelimb was subsequently instrumented with a hybrid dynamic compression plate or a castless pancarpal arthrodesis plate. Biomechanical testing was performed. The forelimbs were statically loaded in the elastic range and then cyclically loaded to failure. Finite element (FE) modeling was used to compare the 2 plate designs with respect to bone and implant stress distribution and magnitude when loaded. Results: Cyclic loading to failure elicited failure patterns similar to those observed clinically. The mean ± SD error between computational and experimental strain was < 15% ± 13% at the maximum loads applied during static elastic loading. The highest bone stresses were at the distal extent of the metacarpal bones at the level of the screw holes with both plates; however, the compression plate resulted in slightly greater stresses than did the arthrodesis plate. Both models also revealed an increase in bone stress at the proximal screw position in the radius. The highest plate stress was identified at the level of the radiocarpal bone, and an increased screw stress (junction of screw head with shaft) was identified at both the most proximal and distal ends of the plates. Conclusions and Clinical Relevance: The FE model successfully approximated the biomechanical characteristics of an ex vivo pancarpal plate construct for comparison of the effects of application of different plate designs.

Objective-To determine the effects of increases in dietary intake of polyunsaturated and saturated fatty acids on plasma lipid and lipoprotein concentrations and activity of associated enzymes in healthy domestic cats. Animals-16 healthy adult sexually intact female cats. Procedures-A baseline diet (40% energy from fat) and 4 test diets, with increased amounts of fat (51% and 66% energy from fat) from the addition of polyunsaturated and saturated fatty acids, were fed for 6 weeks each. Plasma cholesterol, triglyceride, and lipoprotein cholesterol concentrations, along with activities of lipoprotein lipase, hepatic lipase, and lecithin-cholesterol acyl transferase, were measured at the end of each feeding period. Results-Diet, amount of fat, or ratio of polyunsaturated to saturated fatty acids had no effect on plasma concentrations of cholesterol, triglycerides, and very–low-density or high-density lipoproteins or the activity of lecithin-cholesterol acyl transferase. Low-density lipoprotein concentrations were significantly lower in cats fed a high-fat diet containing polyunsaturated fatty acids. Lipoprotein concentration and hepatic lipase activity were significantly higher in cats fed the fat-supplemented diets, and this was unrelated to whether diets were enriched with polyunsaturated or saturated fatty acids. Conclusions and Clinical Relevance-Diets containing up to 66% of energy from fat were tolerated well by healthy cats and did not affect plasma lipid concentrations. Therefore, high-fat diets probably will not contribute to hypercholesterolemia or hypertriglyceridemia in cats.

Objective: To determine MRI characteristics of the skulls and brains of sheep with chronic cerebral coenurosis (CC) caused by naturally acquired Taenia multiceps infection. Animals: 33 sheep with CC and 10 healthy control sheep. Procedures: Sheep underwent MRI of the head. Volumes of the cranial cavity and rostral and caudal fossas of the cranial cavity were determined. For CC-affected sheep, the number, location, and volume of T multiceps cysts were determined and the percentage volumes of cysts in the cranial cavity and rostral and caudal fossas of the cranial cavity were calculated. Focal and diffuse abnormalities of cranial bones in CC-affected sheep were identified. Brain edema and hemorrhage and signs of increased cranial pressure (ICP) in MRI images were determined. Results: Volumes of the cranial cavity and rostral and caudal fossas of the cranial cavity were significantly larger for CC-affected sheep versus healthy control sheep. Total volumes of cysts ranged from 4.40% to 46.93% in cranial cavities of sheep, 4.12% to 51.53% in rostral fossas of cranial cavities of sheep, and 15.24% to 68.30% in caudal fossas of cranial cavities of sheep. Moderate to severe diffuse cranial bone abnormalities and signs of increased ICP in MRI images were detected in 21 and 24 sheep, respectively, and were positively correlated with cyst volumes. Conclusions and Clinical Relevance: Results suggested that cranial cavity volume and morphological abnormalities can be detected in sheep with CC. These changes may reflect abnormalities in ossification of the cranial bones secondary to chronically increased ICP caused by development of T multiceps cysts.

Objective: To evaluate effects of the arytenoid lateralization technique and suture tension on airway pressure in the canine larynx. Sample: 7 canine cadaver larynges. Procedures: Negative pressure was elicited aboral to the larynx. Airway pressure was measured at airflows of 15 to 120 L/min before and after thyroarytenoid lateralization (TAL), cricoarytenoid lateralization (CAL), and combined TAL and CAL (cricothyroarytenoid lateralization [CTAL]) at 100 and 500 g of suture tension and with sectioning of the sesamoid cartilage (SSC) and disarticulation of the cricothyroid joint (DCTJ). Rima glottidis area (RGA) was measured. Effects of technique, modification, and suture tension on pressure and RGA were evaluated statistically. Results: Increased suture tension significantly reduced airway pressure for TAL at 30 L/min, CAL at 45 to 120 L/min, and CAL after SSC and DCTJ at 60, 75, and 105 to 120 L/min. The CAL and CTAL caused significantly lower airway pressures than did TAL > 30 L/min, but SSC and DCTJ did not significantly reduce pressure. All procedures, except TAL at 100 g of tension, resulted in a significant RGA increase from baseline. The CAL and CTAL caused a significantly greater RGA than did TAL. For TAL at 100 g of tension, SSC significantly increased RGA. Conclusions and Clinical Relevance: CAL and CTAL caused lower airway pressures than did TAL. No significant pressure differences were detected between CAL and CTAL; SSC and DCTJ had little effect on pressure. Pressure may be a more sensitive indicator of airflow than is RGA in the larynx of canine cadavers.

Objective: To determine the pharmacokinetic properties of 1 IM injection of ceftiofur crystalline-free acid (CCFA) in American black ducks (Anas rubripes). Animals: 20 adult American black ducks (6 in a preliminary experiment and 14 in a primary experiment). Procedures: Dose and route of administration of CCFA for the primary experiment were determined in a preliminary experiment. In the primary experiment, CCFA (10 mg/kg, IM) was administered to ducks. Ducks were allocated into 2 groups, and blood samples were obtained 0.25, 0.5, 1, 2, 4, 8, 12, 48, 96, 144, 192, and 240 hours or 0.25, 0.5, 1, 2, 4, 8, 24, 72, 120, 168, and 216 hours after administration of CCFA. Plasma concentrations of ceftiofur free acid equivalents (CFAEs) were determined by use of high-performance liquid chromatography. Data were evaluated by use of a naive pooled-data approach. Results: The area under the plasma concentration versus time curve from 0 hours to infinity was 783 h•μg/mL, maximum plasma concentration observed was 13.1 μg/mL, time to maximum plasma concentration observed was 24 hours, terminal phase half-life was 32.0 hours, time that concentrations of CFAEs were higher than the minimum inhibitory concentration (1.0 μg/mL) for many pathogens of birds was 123 hours, and time that concentrations of CFAEs were higher than the target plasma concentration (4.0 μg/mL) was 73.3 hours. Conclusions and Clinical Relevance: On the basis of the time that CFAE concentrations were higher than the target plasma concentration, a dosing interval of 3 days can be recommended for future multidose CCFA studies.

Objective: To determine the effects of intensive serial plasmapheresis on total plasma protein and total IgG concentrations in donor horses involved in a plasmapheresis program. Animals: 18 horses (13 mares and 5 geldings; 13 Belgians, 3 Percherons, 1 Standardbred, and 1 warmblood) ranging from 7 to 14 years of age (mean ± SD, 10 ± 3 years) and weighing 822 ± 128 kg. Procedures: Horses from which 22 mL of plasma/kg of donor body weight was harvested at 14-day intervals for a minimum of 8 consecutive plasmapheresis donations were retrospectively selected for use in the evaluation. Automated plasmapheresis procedures were performed by use of 2 modified plasmapheresis instruments/donor horse. Plasma samples were obtained at each donation and used for determination of total protein and total IgG concentrations. Total plasma protein concentrations were determined via refractometry. A commercially available ELISA was used to determine total equine IgG concentrations. Results: The 18 donor horses were used in 8 to 19 serial donations (mean ± SD, 13 ± 3 donations) during the study. Donor horses had significant decreases in both plasma protein and IgG concentrations over the study period. Conclusions and Clinical Relevance: Serial plasmapheresis procedures caused significant decreases in both plasma protein and IgG concentrations in donor horses; however, decreases were not physiologically relevant. Performing plasmapheresis in horses in accordance with the evaluated automated plasmapheresis procedures did not result in a critical decrease in total plasma protein or total IgG concentrations.