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Abstract

Objective—To quantitatively and qualitatively assess the radiographic appearance of the thorax of clinically normal alpaca crias.

Animals—21 clinically normal alpaca crias.

Procedures—Left-right lateral (LR), right-left lateral (RL), dorsoventral (DV), and ventrodorsal (VD) projections of the thorax were acquired. To account for differences in cria size, measurements of thoracic structures were compared with other anatomic landmarks.

Results—Mean ± SD vertebral heart scale was 9.36 ± 0.65 for LR projections, 9.36 ± 0.59 for RL projections, 8.21 ± 0.51 for DV projections, and 8.65 ± 0.57 for VD projections. Dimensions of the heart were compared with the length of the T3 through T5 vertebral bodies, third to fifth rib distance, and thoracic height and width, which provided additional methods of cardiac evaluation. For RL projections, mean ratio of the right cranial pulmonary artery diameter to the third rib width was 0.41 ± 0.10 and mean ratio of the right cranial pulmonary vein to the third rib width was 0.44 ± 0.10. Caudal lobar pulmonary vessels and the caudal vena cava were difficult to quantitatively assess on DV or VD projections. On lateral projections, the trachea was increased in diameter at the origin of the right cranial lobar bronchus. No qualitative differences were found between LR and RL radiographs. The lungs were generally better inflated on VD projections, with more separation of the heart and diaphragm.

Conclusions and Clinical Relevance—Establishment of radiographic values for alpaca crias should prove useful in assessment of thoracic disease in this species.

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in American Journal of Veterinary Research

Abstract

Objective—To determine the dimensions and volume of thyroid tissue in clinically normal cats by use of computed tomography.

Animals—8 cats.

Procedure—Helical computed tomography images (2-mm collimation) were acquired from the cranial aspect of the second cervical vertebra through the caudal aspect of the fourth cervical vertebra. Data were acquired before contrast medium administration (n = 7 cats) and immediately after contrast medium enhancement (1 cat). Length, width, and height measurements of each thyroid lobe were made by use of transverse, dorsal, and sagittal plane images. Thyroid lobe volume was estimated by use of 3 methods.

Results—All thyroid lobes were histologically normal. Mean dimensions for a thyroid lobe were 16.5 × 2.00 × 4.31 mm (length × width × height) using only data from transverse images. Mean thyroid lobar volume was 113.75 mm3 using the sum of areas method. Mean total volume of thyroid tissue was 215.25 mm3 using the sum of areas method.

Conclusions and Clinical Relevance—Results may be useful for computed tomography evaluation of abnormal thyroid glands in cats, which warrants investigation.

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in American Journal of Veterinary Research

Abstract

Objective

To describe the use of non–contrast-enhanced CT to identify deep digital flexor (DDF) tendinopathy in horses with lameness attributed to pain in regions distal to the metatarsophalangeal or metacarpophalangeal joints.

DESIGN

Retrospective case series.

ANIMALS

28 client-owned horses.

PROCEDURES

Medical records were searched to identify horses that underwent non–contrast-enhanced CT with or without high-field MRI as part of an evaluation for lameness localized to areas distal to the metacarpophalangeal or metatarsophalangeal joint in ≥ 1 limb. Horses were included in the study if they had ≥ 1 DDF tendon lesion (DDF tendinopathy) identified. Signalment, lameness examination findings and response to perineural anesthesia, imaging modality, anesthetic agents and duration of anesthesia, and imaging findings were recorded. Data were summarized descriptively.

RESULTS

Bilateral imaging was performed for all horses, irrespective of unilateral or bilateral lameness. Nine of 28 horses underwent both CT and MRI, and all DDF tendon lesions identified by one modality were identified by the other. Of 48 limbs with DDF tendinopathy, 46 (96%) had core lesions and 35 (73%) had dorsal border irregularities. Median anesthesia time for CT and CT followed by MRI was 15 and 110 minutes, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that non–contrast-enhanced CT was useful for identifying DDF tendinopathy in horses with lameness localized to the phalangeal regions, and this was supported by consistency of findings in a subset of horses that underwent MRI. Further research is needed to confirm these results.

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in Journal of the American Veterinary Medical Association

Abstract

OBJECTIVE

To radiographically compare patellar ligament length (PLL) in dogs undergoing tibial plateau leveling osteotomy (TPLO) for unilateral cranial cruciate ligament rupture at preoperative, postoperative, and follow-up evaluations.

ANIMALS

105 dogs that underwent TPLO for unilateral cranial cruciate ligament rupture at a referral veterinary hospital from October 1, 2008, through November 30, 2017.

PROCEDURES

Medical records were reviewed to obtain information on dog signalment, surgical procedure, and radiographically measured PLL at preoperative, postoperative, and follow-up evaluations.

RESULTS

Dogs undergoing TPLO had a shorter PLL at the postoperative and follow-up evaluations, compared with the PLL at the preoperative evaluation. Mean ± SD overall unadjusted PLL decreased significantly by 2.3 ± 3.4% between the preoperative and postoperative evaluation and by 2.8 ± 3.9% between the preoperative and follow-up evaluation. The PLL did not differ significantly between the postoperative and follow-up evaluation; mean PLL decreased by 0.4 ± 3.8% between the postoperative and follow-up evaluation.

CONCLUSIONS AND CLINICAL RELEVANCE

The PLL was shorter after TPLO in dogs, which was similar to changes observed for humans after high tibial osteotomy procedures. Further evaluation of clinical assessments, joint mobility, ultrasonographic assessments, and kinematic results are needed to determine the relevance of the PLL and whether a decrease in ligament length results in decreased mobility and persistent lameness in dogs, as has been reported for humans.

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in American Journal of Veterinary Research
History

A 9-year-old 500-kg (1,100-lb) American Quarter Horse gelding used for barrel racing was referred for evaluation of right forelimb lameness of several weeks’ duration that had not resolved with rest. When examined by the referring veterinarian on the farm approximately 5 days before the referral examination, the horse had a grade 3/5 lameness in the right forelimb and substantially limited range of motion in its neck, particularly toward the left. Severity of the lameness increased when flexion tests were performed on the carpal, elbow, and shoulder joints of the affected limb, and lameness was not abolished by regional anesthesia

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To measure the effects of lowmolecular-weight inhibitors on the activity of bovine neutrophil matrix metalloproteinase 9 (MMP-9).

Sample Population—Bovine MMP-9 purified from bovine neutrophilconditioned medium.

Procedures—Neutrophils were degranulated by stimulation with phorbol ester. Enzyme purification was performed by use of gelatin affinity and gel-filtration chromatography. Activated enzyme was incubated with inhibitors prior to addition of substrate (gelatin fluorescein conjugate or fluorogenic peptide). Rates of enzymatic cleavage were determined by monitoring fluorescence as the reactions progressed. Values of IC50 (molar concentration of compound that inhibits specific activity by 50%) and KI (in vitro inhibition constant) were determined.

Results—Rates of enzymatic activity of monomeric and dimeric bovine MMP-9 measured by use of gelatin and peptide substrates were linear with respect to time and concentrations of enzyme and substrate. The MMP-9 was potently inhibited by hydroxamic acids (IC50 for gelatin, 29.2 to 55.7nM; IC50 for peptide, 4.8 to 24.6nM; KI, 0.2 to 0.5nM), whereas tetracyclines (IC50 for gelatin, 30.1 to 112.7MM; IC50 for peptide, 48.0 to 123.8MM; KI, 25.2 to 61.4µM) and chlorhexidine (IC50 for gelatin, 139.1MM; IC50 for peptide, 672.5MM to 1.7mM; KI, 495.0 to 663.0MM) had limited inhibition. Gelatinase-specific inhibitor SB-3CT had intermediate potency (IC50 for peptide, 185.0 to 290.0nM; KI, 66.5 to 86.0nM).

Conclusions and Clinical Relevance—Bovine MMP-9 was potently inhibited by hydroxamic acids and gelatinase inhibitor. These compounds may be useful as modulators of neutrophil-mediated protease activity in cattle.

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in American Journal of Veterinary Research

Abstract

Objectives—To quantify direction and velocity of blood flow in hepatic veins in dogs under different hemodynamic conditions by use of pulsed-wave Doppler ultrasonography.

Animals—10 healthy dogs.

Procedure—Dogs were anesthetized, and venous flow velocities in the quadrate lobe were measured. Arterial blood pressure, right atrial pressure, pulmonary artery pressure, and cardiac output were measured simultaneously. The timing of each waveform during the cardiac cycle was used to identify velocity profiles. Peak waveform velocities were measured during conditions of light anesthesia with isoflurane (baseline; period 1), cardiovascular depression following administration of highdose isoflurane and esmolol IV (period 2), cardiovascular depression with crystalloid volume expansion (period 3), and high cardiac output induced with dobutamine (period 4). Hemodynamic measurements and maximum waveform velocities were compared among the 4 periods by use of an ANOVA and univariate and multivariate linear regression.

Results—During each study period, 4 distinct, lowvelocity waves were identified. Mean velocities recorded during period 1 were as follows: retrograde atrial contraction a-wave, 7.3 cm/s; antegrade systolic S-wave, 15.0 cm/s; retrograde venous return v-wave, 2.7 cm/s; and antegrade diastolic D-wave, 11.4 cm/s. Mean S:D ratio was 1.27. During periods 3 and 4, Swave velocity increased; D-wave velocity was highest during period 4.

Conclusions and Clinical Relevance—Consistent hepatic venous velocity profiles were observed in healthy dogs under different hemodynamic conditions. These findings provide baseline values that may be useful in evaluating clinical cases, but further study involving healthy, awake dogs and dogs with cardiac and hepatic diseases is required. (Am J Vet Res 2004;65:734–740)

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in American Journal of Veterinary Research

Abstract

Objective—To determine whether the reported drug-drug interaction between the flea medication spinosad and ivermectin is attributable to inhibition of P-glycoprotein by spinosad.

Animals—6 healthy adult dogs with the ABCB1 wildtype genotype.

Procedures—The study was conducted as a prospective, masked, randomized crossover design. Six dogs were allocated to 2 groups; each dog served as its own control animal. Dogs in one of the groups received spinosad at the manufacturer's recommended dose; the other group received no treatment. Forty-eight hours later, scintigraphic imaging of the head and abdomen were performed with the radiolabeled P-glycoprotein substrate methoxy-isobutyl-isonitrile (sestamibi) in both groups of dogs. After a washout period of 60 days, the dogs in each group received the alternate treatment, and scintigraphic imaging again was performed 48 hours later. Gallbladder-to-liver and brain-to-neck musculature ratios of technetium Tc 99m sestamibi were calculated for each dog and compared between treatments.

Results—No significant differences in gallbladder-to-liver or brain-to-neck musculature ratios were found between treatments.

Conclusions and Clinical Relevance—Results provided evidence that spinosad did not inhibit P-glycoprotein function 48 hours after spinosad was administered at the manufacturer's recommended dose. Further investigations will be necessary to elucidate the mechanism of the reported toxic interaction between spinosad and ivermectin.

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in American Journal of Veterinary Research

Abstract

Objective—To evaluate and correlate patterns of subchondral bone density and articular cartilage degeneration (derived by use of gross, histologic, and computed tomographic [CT] examinations) in equine third metacarpal condyles with and without osteoarthritis.

Sample Population—8 metacarpophalangeal (MCP) joints (n = 4 horses) without osteoarthritis and 6 osteoarthritis-affected MCP joints (4).

Procedures—Horses were euthanized. The third metacarpal condyles of the joints were examined grossly and via CT (3 slice images/condyle). For 6 condylar zones, mean bone density and pattern of density distribution were determined. Data for osteoarthritis-affected and control joints were compared. Histomorphometric point count analyses identified areas of bone density for comparison with CT density measurements.

Results—Osteoarthritis-affected condyles had heterogeneous subchondral bone with focal resorptive lesions and patterned sclerosis, whereas control condyles had symmetric bone density distribution. In osteoarthritis-affected condyles, bone density determined via gray scale image density analysis was greater (dorsal and medial pattern), compared with control condyles, and differed among zones because of resorption and sclerosis. With regard to bone density in osteoarthritis-affected condyles, histologic findings correlated with CT images, and bone lesions were significantly correlated with cartilage lesions.

Conclusions and Clinical Relevance—In horses, heterogeneous distribution and greater subchondral bone density were characteristic of osteoarthritis-affected condyles, compared with control condyles. Subchondral bone lesions correlated with overlying cartilage lesions in osteoarthritis-affected MCP joints. Identification of CT image characteristics appears to predict the presence of a cartilage lesion in MCP joints of horses with osteoarthritis.

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in American Journal of Veterinary Research

Abstract

Objective—To develop protocols for helical computed tomography (CT) and axial high-resolution CT (HRCT) of lungs and correlate densitometric CT values with morphometric and histologic data for normal pulmonary tissue in dogs.

Animals—8 healthy adult dogs.

Procedure—2 dogs were used to establish a protocol for helical CT and HRCT of lungs. Six dogs were used to acquire densitometric CT data regarding normal lungs. After the dogs were euthanatized, their lungs were fixed and sampled for morphometric and histologic evaluation. Four CT acquisitions were compared by means of paired t tests.

Results—For normal lung tissue of dogs, mean densitometric CT value obtained during helical CT scans reconstructed in a sharp algorithm was -846 Hounsfield units. Values obtained via helical CT or HRCT acquisitions and reconstructed with sharp or standard algorithms did not differ significantly. Morphometric analysis was used to determine the proportion of lung parenchymal (82%) and nonparenchymal tissue (18%). Alveolar size, estimated by mean linear intercept, was approximately 172 µm, and alveolar surface area-to-volume ratio was 0.024 to 0.026 µm–1. Histologic evaluation confirmed the presence of normal lung tissue.

Conclusions and Clinical Relevance—Correlation of densitometric CT data with morphometric and histologic findings and the establishment of helical CT and HRCT protocols were attained; clinical use of this information may facilitate investigation of pulmonary disease in dogs. Sharp helical CT acquisitions were preferred because of better lung parenchyma detail and rapid image acquisitions, compared with HRCT. (Am J Vet Res 2003;64:935–944)

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in American Journal of Veterinary Research