Dual-Energy X-Ray Absorptiometry and Force-Plate Analysis of Gait in Dogs With Healed Femora After Leg-Lengthening Plate Fixation

Dual-energy x-ray absorptiometry was used to measure bone mineral density of four regions in healed femora of nine dogs after fracture fixation with a leg-lengthening plate. Six to 85 months (mean, 46 months) after surgery, the bone mineral density of healed femora was not significantly different from the contralateral uninjured femora ( P >.05; power = 0.8 at Δ= 15%). Radio-lucencies around the proximal screws, apparently associated with screw loosening, were seen on radiographic views of the healed femora of three dogs. In one of these dogs, one screw in the proximal metaphysis had broken. Force-plate analysis of gait was also performed on dogs at the time of bone mineral density measurement. Peak vertical force was decreased in the pelvic limb with the healed fracture compared with the contralateral unoperated limb ( P < 0.05). Clinically apparent lameness in three dogs did not appear to be associated with altered bone mineral density and may have been caused by hip osteoarthritis, a nondisplaced hairline diaphyseal fracture, and screw loosening in conjunction with extensive post-traumatic soft tissue injury.     

Treatment of Humeroulnar Subluxation with a Dynamic Proximal Ulnar Osteotomy A Review of 13 Cases

Humeroulnar subluxation was treated surgically in 13 dogs with 18 affected elbows using a proximal osteotomy of the ulna that allowed the ulna to elongate dynamically. Distal humeroulnar subluxation was secondary to premature closure of the distal ulnar physis in 16 elbows. One distal subluxation was secondary to a radioulnar synostosis, and one proximal subluxation developed after premature closure of the distal radial physis. The mean follow-up time was 22 months. Twenty-eight percent of the elbows were judged to have excellent results, 22% good results, 50% fair results, and none was judged to have a poor outcome. The presenting lameness grade and the severity of preoperative and postoperative humeroulnar subluxation had significant correlations with the prognosis. Associated orthopedic abnormalities and complications of concurrent surgical procedures affected the outcome in several dogs. Overall, the dynamic proximal ulnar osteotomy was a simple and effective technique for the treatment of uncomplicated humeroulnar subluxation.     

Duration of antigen-induced hyperresponsiveness in horses with allergic respiratory disease and possible links with early airway obstruction

Fairbairn, S.M., Lees, P., Page, C.P., Cunningham, F.M. Duration of antigen-induced hyperresponsiveness in horses with allergic respiratory disease and possible links with early airway obstruction. J. vet. Pharmacol. Therap. 16, 469–476.
Antigen-induced airway hyperresponsiveness in allergic horses has previously been demonstrated when clinical signs of acute airway obstruction were apparent, as a consequence of exposure of animals to hay and straw for variable periods of time, and repeat measurements of hyperresponsiveness have been made no earlier than 1 week after challenge. In the present study airway responsiveness to methacholine has been measured in normal horses and allergic horses in clinical remission before and 24, 48 and 72 h after a hay and straw challenge of fixed, short, duration (7 h). Correlations between early increases in interpleural pressure and hyperresponsiveness have also been investigated. As in other studies, the mean airway responsiveness of groups of normal and allergic horses in clinical remission was not significantly different. The responsiveness to methacholine of allergic, but not normal, horses was increased after antigen challenge and was significantly greater than that of normal horses at 48 and 72 h after challenge (log PD _{8 cm}: -0.77 ± 0.28 vs. 0.27 ± 0.14 at 48 h and -0.6 ± 0.25 vs. 044 ± 01 at 72 h; P < 0.05). There was also a significant correlation between interpleural presssure at the end of the 7-h challenge in allergic horses and the increase in responsiveness to methacholine at 24, 48 and 72 h. These results demonstrate that antigen induces an increase in airway responsiveness in allergic horses that persists for up to 3 days and which may be linked to the initial increase in interpleural pressure.     

Actions of non-steroidal anti-inflammatory drugs on equine leucocyte movement in vitro

The direct effects of four non-steroidal anti-inflammatory drugs (NSAIDs) on equine polymorphonuclear (PMN) and mononuclear (MN) leucocyte movement were investigated using two in vitro assay systems. The Boyden chamber microfilter technique measures both chemokinetic and chemotactic locomotion, and the agarose microdroplet assay measures solely chemokinesis. Zymosan-activated plasma (ZAP) and the synthetic peptide N-formyl-methionyl-leucyl-phenylalanine (FMLP) were used as standard chemoattractants for PMN and MN leucocytes, respectively. The actions of six concentrations of each NSAID, indomethacin (50 microM-10 mM), phenylbutazone (10 microM-1 mM), oxyphenbutazone (2.5 microM-500 microM) and flunixin (0.1 microM-50 microM), in suppressing cell movement induced by ZAP and FMLP were investigated. All four drugs exerted inhibitory effects on induced movement of both cell types in the Boyden chamber assay, usually in a concentration-dependent manner, although oxyphenbutazone action on PMN cells occurred only at the highest concentration tested. Significant inhibition of PMN and MN cell locomotion was produced by indomethacin, flunixin and oxyphenbutazone, and inhibition of PMN movement by phenylbutazone occurred in the agarose microdroplet assay. Flunixin was the most potent of the four drugs investigated in both assay systems. The findings may be of importance to the use of phenylbutazone and flunixin as NSAIDs in equine medicine, since the concentrations used were similar to concentrations of both drugs and the phenylbutazone metabolite oxyphenbutazone previously reported to occur in equine plasma and inflammatory exudate.     

Hip dysplasia in a cat

The clinical and radiographical features of hip dysplasia in a Persian cat are described. Pectineus myotendonectomy produced only a temporary improvement and coxofemoral excision arthroplasty was performed. This resulted in complete remission of the signs and symptoms.     

EVALUATION OF 99MTC-DIETHYLENETRIAMINEPENTAACETIC ACID RENAL SCINTIGRAM CURVES IN NORMAL DOGS AFTER INDUCTION OF DIURESIS

The normal 99mTc-diethylenetriaminepentaacetic acid (DTPA) renal scintigram curve has 3 distinct phases; an arterial phase followed by progressive uptake and subsequent excretion from the kidney. In dogs with X-linked hereditary nephritis, a distinct flattening of the renal scintigram curve has been observed prior to any decline in glomerular filtration rate (GFR). The cause of this shape change is not known, however, it coincided with decreased urine-specific gravity and thus might be related to polyuria. To further evaluate this possibility, we assessed whether diuresis without concurrent renal disease could flatten the 99mTc-DTPA renal scintigram curve. GFR scintigraphy was performed in six healthy dogs once as a baseline, and again after induction of diuresis by each of four different methods. Scintigram curves were evaluated subjectively as well as quantitatively by calculation of GFR estimates, mean renal transit times, time to peak activity and half-time clearance. Complete flattening of the renal scintigram curve did not occur with diuresis alone, and therefore, flattening of the scintigram curve may serve as an early indicator of renal dysfunction. However, during diuresis after intravenous saline administration, alterations in time to peak activity and mean renal transit time may create inaccuracies in GFR estimates based on the conventional regression formula that cause a false lowering of the resultant global GFR value.     

EFFECT OF OBSERVER VARIABILITY ON GLOMERULAR FILTRATION RATE MEASUREMENT BY RENAL SCINTIGRAPHY IN DOGS

Observer variation in kidney depth measurement for correction of soft-tissue attenuation and kidney region of interest (ROI) drawing was evaluated using 60 clinical dogs with a wide range of glomerular filtration rate (GFR) for their effect on the calculated percentage uptake of 99mTc-diethylenetriamine pentaacetic acid (DTPA) and individual kidney GFR by scintigraphy. Kidney depth was measured separately on the lateral image using two color tables: a threshold and a continuous red-green-blue. Within-observer variability of the semi-automatic ROI drawing of the estimated total GFR was up to 10% for the right kidney (RK) and 9% for the left kidney (LK). The variability was lower between observers, 6% for RK and 8% for LK. Manual ROI drawing caused more within observer variation than semi-automatic: up to 14% for RK and 11% for LK. Continuous red-green-blue table caused more variation within and between observers than threshold table. Average within-observer variability from both observers of kidney depth measurement on different color tables could vary up to 5.5% and 6.5% variation of the GFR of RK and LK, respectively. Most variation affecting the DTPA percentage uptake came from the ROI drawing technique. Variations of the method because of the effects of both kidney depth and kidney ROI drawing were up to 8% and 10% for RK and LK, respectively. To minimize these variations a threshold scale should be used for the kidney depth measurement and an automatic or semi-automatic ROI should be used whenever possible. In sequential examinations the same person should make all the measurements.     

INVESTIGATION OF TWO METHODS FOR ASSESSING THYROID-LOBE ASYMMETRY DURING PERTECHNETATE SCINTIGRAPHY IN SUSPECTED HYPERTHYROID CATS

Our aim was to investigate thyroid:thyroid (T:T) ratio and visual inspection for assessing thyroid-lobe asymmetry in suspected hyperthyroid cats. Although thyroid-salivary asymmetry is a preferred test, inherent thyroid symmetry may assist image interpretation. Association was determined using a scatter plot and Spearman's rank correlation. Agreement was assessed using the kappa (K) statistic. Accuracy was assessed by sensitivity and specificity. Hyperthyroidism was diagnosed in 33/48 (69%) cats based on elevated serum total thyroxine level. Using two Wilcoxan rank-sum tests, a significant difference (P < 0.0001) was detected between cats with and without hyperthyroidism for both methods of assessing thyroid symmetry. For the 18 cats with T:T ratios < or = 1.5, there was poor correlation between the two methods (r(s) = 0.39). Using a cut-point of 1.5 for the T:T ratio, the test accurately predicted hyperthyroidism in 28/33 cats (sensitivity, 85%; 95% confidence interval (CI), 71-99%) and correctly predicted that hyperthyroidism was absent in 14/15 cats (specificity, 93%; CI, 77-100%). For visual inspection, agreement for diagnosing hyperthyroidism was excellent between methods (kappa = 0.82), within the same examiner (weighted kappa = 0.85) and between examiners (weighted kappa = 0.89). Considering cats with only definitely asymmetric thyroid lobes as positive, visual inspection accurately predicted hyperthyroidism in 28/33 cats (sensitivity, 85%; CI, 71-99%) and correctly predicted that hyperthyroidism was absent in 11/15 cats (specificity, 73%; CI, 48-99%). Thyroid-lobe asymmetry occurs more frequently in hyperthyroid than in euthyroid cats but caution should be exercised because some euthyroid cats have asymmetric thyroid glands.