DIURETIC RENAL SCINTIGRAPHY IN NORMAL DOGS

Diuretic renal scintigraphy is commonly used in human medicine to differentiate obstructive from nonobstructive pyelectasia. In order to determine normal parameters, 99mTc-DTPA renal scintigraphy was performed twice in 20 healthy adult Mongrel dogs. Each dog was injected with either 3.0 mg/kg furosemide or an equivalent volume of saline 4.5 min following injection of the radiopharmaceutical. The following parameters were evaluated: (1) global and individual glomerular filtration rate (GFR); (2) time of peak (TOP) of the time-activity curve (TAC); (3) shape of the TAC; (4) individual kidney excretion half-time (T1/2); (5) proportion of maximum activity measured at end of study (8 min); (6) time of onset; and (7) duration of the effect of the diuretic. Most TAC in the diuretic renography group showed a steep drop in the curve following administration of the diuretic compared with a gradual slope in the saline control group. There was a statistically significant difference in T1/2 between the control renograms (median 10.25 min, range 4.41-18.07 min) and the diuretic renograms (median 4.16 min, range 3.62-5.90 min). There was a statistically significant difference in percentage maximum activity between the control renograms (median 65.25%, range 48.27-93.68%) and the diuretic renograms (median 48.54%, range 35.64-58.76%). Median time of onset of the diuretic effect was 1.10 min (0.20-2.40 min), and median duration was 0.83 min (0.30-2.35 min).     

Hyperparathyroid disorders in the dog: primary, secondary and cancer-associated (pseudo)

Hyperparathyroid disorders were diagnosed in four dogs: one had primary hyperparathyroidism, characterized by parathyroid adenoma and hyper-calcaemia; one had renal secondary hyperparathyroidism, characterized by parathyroid gland hyperplasia, hypocalcaemia and renal failure; and two had cancer-associated hyperparathyroidism (pseudohyperpara-thyroidism), characterized by the presence of neoplasia, parathyroid gland atrophy, hypercalcaemia and absence of skeletal metastases. Significant clinicopathologic findings included serum concentrations of calcium, phosphorus and immunoreactive parathyroid hormone (PTH), presence or absence of parathyroid and bone lesions, and the presence of non-parathyroid neoplasia.     

Canine lymphosarcoma and hypercalcaemia: clinical, laboratory and pathologic evaluation of twenty-four cases

Twenty-four dogs with lymphosarcoma and hypercalcaemia were studied clinically, haematologically and biochemically. There was no age or breed predilection, although the St Bernard dog appeared to be over-represented. Male dogs were more frequently affected (62 per cent) than female dogs. Anorexia, weight loss, muscular weakness, depression, polydipsia, polyuria, and bilateral peripheral lymphadenopathy were the most frequently observed clinical signs and physical findings. Hypercalcaemia, creatinaemia, azotaemia, hypercalciuria, hyposthenuria, and decreased endogenous creatinine clearance were the most frequent laboratory abnormalities. Detailed gross and histopathologic examinations of 10 dogs revealed the multicentric anatomic form of lymphosarcoma, absence of skeletal metastases, and normal parathyroid glands. The dogs were clinically staged, and ten were histologically classified. Histologic staging revealed five diffuse histiocytic lymphomas, and five diffuse lymphocytic poorly differentiated lymphomas.     

The influence of forage quality and concentrate level on dry matter intake and milk production of British Friesian heifers

Thirty-six British Friesian heifers were divided into two groups during weeks 3-26 of lactation and received ad libitum either good (G) or average (A) quality grass silage. The in vitro digestible organic matter in the DM was 680 and 600 g kg^-1 for silages G and A, respectively. In addition, the heifers in each group were offered concentrate at either a low (4.3 kg DM d^-1), medium (64 kg DM d^-1) or high (8.4 kg DM d^-1) level. The concentrate contained 180 g (kg DM)^-1 of crude protein and had a calculated metabolizable energy concentration of 12.9 MJ (kg DM)^-1. Increasing concentrate level significantly increased milk yield (P < 0.01), milk protein concentration (P < 0.05), and yield of both milk protein depressed milk fat concentration (P < 0.001) and silage intake (P < 0.001). Although the overall effect of silage quality on milk yield was not significant, the milk yields for silage G at each concentrate level were higher, significantly so for low level, than the corresponding values for silage A. An improvement in silage quality did not affect milk fat concentration but significantly increased the concentration of milk protein (P < 005) and yields of both milk fat (P < 005) and protein (P < 0001). The response of silage DM intake to improved silage quality was 0 06 kg DM per 10 g rise in vitro DOMD value. Each additional kg concentrate DM depressed intake of silages G and A by 0-63 and 0-27 kg DM, respectively. Substitution rate was also significantly related to stage of lactation. With both silages, the digestibility coefficients determined in vivo for acid detergent fibre (ADF) decreased significantly (P < 0.001) when concentrate level was increased from low to high. Differences for DM, OM and total N digestibility coefficients between treatments were not established as significant at the 5% level. Estimates of mean efficiency of utilization of ME for lactation, made on a weekly basis, were 049 and 052 for the heifers given silages G and A. respectively, and 048, 052 and 052 for those given the low, medium and high levels of concentrate. Energy balances were calculated on a mean weekly basis.     

Evidence of the development of ‘domain‐restricted’ expertise in the recognition of asymmetric motion characteristics of hindlimb lameness in the horse

Reasons for performing study: Visual assessment of horses' movements is subjective, affected by bias and dependent on the level of experience of the assessor. However, to date there are no data available on the ability of the human visual system to recognise (a)symmetry in moving objects. Objectives: To investigate, using visual lameness assessment, the limits of human perception and the ability of experienced and nonexperienced individuals to detect asymmetry in 2 moving objects simulating hindlimb lameness in the horse. Methods: Twelve experienced individuals (equine and small animal clinicians), and 24 nonexperienced individuals (undergraduate veterinary students) were presented with computer simulations showing 2 ‘tuber coxae markers’ created using data from both lame and nonperceptibly lame horses, as well as artificial data based on a sine wave. Individuals were asked to classify as symmetrical or asymmetrical, and then rank based on the grade of perceived asymmetry. Repeatability and learning effect were evaluated by repeating the tests on a subset of subjects. Results: The threshold for detection of movement asymmetry was found to be approximately 25% difference in amplitude between the 2 moving objects for all individuals. There was no significant difference between experienced and nonexperienced individuals in the ability to detect asymmetry in the simulations based on artificial data. However, the percentage of correct answers was higher for experienced compared to nonexperienced individuals for simulations based on data from real lame horses. Conclusions: There was a significant difference between experienced and nonexperienced individuals in the ability to identify asymmetric movement based on the pattern seen in a lame horse, as opposed to an artificial pattern for which all individuals showed similar performance. Potential relevance: The study provides the basis for the development of computer simulations that could aid in training veterinarians in the diagnosis of lameness and, even, the objective assessment of expertise in this field.     

The effect of training on stride parameters in a cohort of National Hunt racing Thoroughbreds: A preliminary study

Reasons for performing study: The influence of training on stride parameters is controversial and to date there is no information on how training influences stride parameters during high‐speed locomotion in the field. Objective: To determine the influence of training on stride variables during high‐speed locomotion in Thoroughbred racehorses. Methods: Speed, stride frequency, stance and protraction times were quantified in 8 Thoroughbreds with foot mounted accelerometers and GPS sensors during their first week of canter after the summer break and 6 months into training. Results: At a speed of 11 m/s, stride frequency was (mean ± s.d.) 2.160 ± 0.120 strides/s pre‐ and 2.167 ± 0.083 strides/s post training; mean stance time was 125.3 ± 9 ms pre‐ and 125.9 ± 7 ms post training; protraction time was 340.7 ± 20.4 ms pre‐ and 337.2 ± 14.3 ms post training. The increase in stride frequency and the decrease in protraction time after training were significant. There was no statistically significant difference in the maximum speed reached by each horse pre‐ and post training. Conclusions: Stance time stayed constant throughout the training season in the tested horses. A significant decrease in protraction time and a corresponding significant increase in stride frequency were observed after training. Potential relevance: Training of racehorses could be adapted to maximise the effect on modifiable parameters and reduce the risk of training‐induced pathologies. Further research will be conducted to investigate the effect of different training protocols on a large number of horses.     

Effect of Prosthesis Number and Position on Rima Glottidis Area in Equine Laryngeal Specimens

Objective— To assess the effect of 1 or 2 laryngeal prosthetic sutures on rima glottidis areas in equine laryngeal specimens. Study Design— Experimental, randomized design. Animals— Cadaveric equine larynges (n=16). Methods— Larynges were collected from 10 horses; 2 sutures each were preplaced in the right and left sides of each larynx. A dorsal suture (DS) was placed through the caudal rim of the dorsal midline of the cricoid cartilage, under the cricopharyngeus muscle and through the proximal and rostral aspect of the muscular process. A lateral suture (LS) was placed 1.5 cm lateral to the DS and through the muscular process more distal and caudal to the 1st suture. Larynges were positioned in a customized stand and the rima glottidis photographed after each suture (LS or DS) or suture combination (CS) was tied in random sequence. An additional 6 larynxes were used to determine whether the tension applied to the sutures was repeatable. Sutures were preplaced in both the right and left side of each larynx as described above and each suture and CS was tied and released 3 times in each larynx. Photographs were taken of the rima glottidis after each suture or CS was tied generating 3 replicates for each suture configuration on each side of the 6 larynges. Results— Mean rima glottidis area was not different between DS and LS when tied alone (P=.85); however, mean area after CS (DS+LS) was greater than DS (P<.001) and LS (P<.001) alone. The coefficient of variation for the 6 suture patterns were low (1–7%) and the intraclass correlation coefficient estimates were very high (0.997–0.998) demonstrating excellent repeatability between replicates for each of the 3 suture configurations. Conclusion— Our results suggest that laryngoplasty using 2 prostheses; 1 placed dorsally in the cricoid and through the rostral and proximal muscular process and 1 placed 1.5 cm lateral to the 1st and more caudal and distal in the muscular process results in a greater cross sectional area of the rima glottidis than either suture used alone. Clinical Relevance— Seemingly prosthetic sutures contribute independently to each other in determining the contour of the rima glottidis. Use of 2 prosthetic sutures improves crosssectional area of the rima glottidis compared with each suture alone and may improve surgical outcome in laryngoplasty.     

Intra‐ and interobserver agreement in the interpretation of navicular bones on radiographs and computed tomography scans

Reasons for performing study: Criteria for the radiographic evaluation of navicular bones in horses have been published to standardise classification of radiographic signs. However, intra‐ and interobserver agreement have not been established. Objective: To determine intra‐ and interobserver agreement in the evaluation of radiographic and computed tomographic (CT) navicular changes. It was hypothesised that: 1) intraobserver agreement would be better than interobserver agreement; 2) agreement would be better for CT than for radiography; and 3) pathological changes would be recognised with greater certainty with CT. Methods: Radiographs and CT scans of 60 cadaver navicular bones were evaluated by 3 observers using published criteria. A subset of 30 studies was evaluated twice by one observer. Agreement was tested using the kappa statistic. Certainty about pathological changes was evaluated by giving the observers the option to choose ‘not sure’. Results: Agreement varied from poor to almost perfect for radiographic evaluation and from poor to substantial for CT evaluation. For radiographic evaluation mean interobserver agreement was fair, as it was for CT evaluation. For radiographic evaluation mean intraobserver agreement was moderate as it was for CT evaluation. Pathological changes were evaluated with greater certainty on CT scans compared to radiographs; however, this was not associated with improved agreement. Conclusions: Variations in classification of navicular lesions in radiographic and CT studies were considerable between and within observers and challenge the use of such studies for diagnostic and prognostic purposes. Potential relevance: The results of this study allowed the identification of evaluation criteria with sufficient precision to be useful for navicular bone evaluation.     

Two‐ and three‐dimensional computed tomographic anatomy of the enamel,infundibulae and pulp of 126 equine cheek teeth. Part 2: Findings in teeth with macroscopic occlusal or computed tomographic lesions

Reasons for performing study: Dental disease often presents a diagnostic challenge in the horse. Computed tomography (CT) is increasingly used in the evaluation of head related disease in the horse, but the CT appearance of the most common dental diseases of horses has not yet been fully described. Objective: To describe the CT appearance of the peripheral enamel, pulp, infundibular enamel and cement in equine cheek teeth with macroscopic occlusal or CT lesions. Methods: In this study, 126 cadaveric cheek teeth with eruption ages of between 0.5 and 19 years were evaluated for lesions of their infundibulae, pulp and enamel using occlusal surface morphology, 2‐ (2D) and 3‐dimensional (3D) CT and anatomical sectioning. Variations in teeth with no macroscopic lesions have been described in a previous study. The infundibular lesions were categorised further into one of 6 classifications. Results: Infundibular lesions were identified on CT in 90% (115/128) of infundibulae. Of these, 65% (83/128) had infundibular lesions on occlusal surface examination. The extent of infundibular lesions observed varied with age group. All infundibulae over 6 years post eruption had detectable lesions. Peripheral enamel hypoplasia and enamel prolapses, were observed in 10% (12/126) and 1.6% (2/126) of teeth, respectively. The CT appearance of teeth with pulp infections was seen to vary with differing pathologies. Conclusions and potential relevance: The high prevalence of infundibular lesions should encourage consideration of their clinical significance, in addition to the role of infundibulae in dental disease of the horse. Two‐dimensional and 3D CT proved to be highly valuable imaging modalities for dental disease, enabling lesions within the enamel, infundibulae and pulp of equine cheek teeth to be easily detected. The results of this study will facilitate the use of 2D and 3D CT as clinical diagnostic tools for dental disease and aid in the selection of the most appropriate treatment protocol.