Outcomes, complications and risk factors following fluoroscopically guided transcondylar screw placement for humeral intracondylar fissure.

OBJECTIVES: To describe the surgical technique and complications for fluoroscopically guided transcondylar screw placement for humeral intracondylar fissure in dogs. MATERIALS AND METHODS: A retrospective review was undertaken of cases from two hospitals where identical surgical technique was employed. Factors were analysed for any association with postoperative complications. RESULTS: Sixty-two dogs (82 elbows) were reviewed for which the postoperative complication rate was 45%; a total of 15% of cases required revision surgery. Complications were more likely in cases operated on earlier in the case series and with increasing dog bodyweight. Both increasing surgical time and being a neutered female were protective against postoperative complications. CLINICAL SIGNIFICANCE: Fluoroscopically guided transcondylar screw placement for humeral intracondylar fissure is associated with a high postoperative complication rate (45%) with 15% of cases requiring revision surgery.

Skull morphology diverges between urban and rural populations of red foxes mirroring patterns of domestication and macroevolution.

Human activity is drastically altering the habitat use of natural populations. This has been documented as a driver of phenotypic divergence in a number of wild animal populations. Here, we show that urban and rural populations of red foxes (Vulpes vulpes) from London and surrounding boroughs are divergent in skull traits. These changes are primarily found to be involved with snout length, with urban individuals tending to have shorter and wider muzzles relative to rural individuals, smaller braincases and reduced sexual dimorphism. Changes were widespread and related to muscle attachment sites and thus are likely driven by differing biomechanical demands of feeding or cognition between habitats. Through extensive sampling of the genus Vulpes, we found no support for phylogenetic effects on skull morphology, but patterns of divergence found between urban and rural habitats in V. vulpes quantitatively aligned with macroevolutionary divergence between species. The patterns of skull divergence between urban and rural habitats matched the description of morphological changes that can occur during domestication. Specifically, urban populations of foxes show variation consistent with 'domestication syndrome'. Therefore, we suggest that occurrences of phenotypic divergence in relation to human activity, while interesting themselves, also have the potential to inform us of the conditions and mechanisms that could initiate domestication. Finally, this also suggests that patterns of domestication may be developmentally biased towards larger patterns of interspecific divergence.

Reliability of CT measurement of induced radioulnar step in dogs using a circle superimposition technique.

OBJECTIVES: To evaluate the reliability of CT measurement of canine elbow axial radioulnar congruence using a duplicated circle superimposition technique. MATERIALS AND METHODS: CT of six cadaveric canine elbows was performed following either: (1) placement of an external fixator on the radius with ostectomy and radial shortening of 1 to 5 mm; (2) radial lengthening of 1 to 5 mm using a radial lengthening system; or, (3) no axial length adjustment. Four observers, on two occasions, blinded to the amount of radial adjustment, placed a circle of best fit of the ulnar trochlear notch on a sagittal image that was duplicated and transposed to the articular contour of the radial head; then the axial distance between circles relative to the dorsal radius was measured. Statistical analysis assessed differences between actual and observer-assessed radial length adjustment; inter-/intra-observer interclass correlation coefficients and sensitivity/specificity were calculated to evaluate measurement reliability. RESULTS: There was not a significant difference between actual and observer measures of radioulnar congruence. Inter- (intraclass correlation coefficient=0.98) and intra-observer reliability (intraclass correlation coefficient=0.94 to 0.99) were almost perfect for measurement of radioulnar incongruence when compared to the actual radial adjustment. A Bland-Altman plot revealed a 95% confidence interval range of -1.31 to 1.16 mm. Sensitivity and specificity were high for correct identification of congruent elbows and elbows with 1 or 2 mm incongruency. CLINICAL SIGNIFICANCE: The duplicated circle superimposition technique provides a simple and accurate means of assessing radioulnar axial incongruence.

Intra- and inter-observer agreement in histological assessment of canine soft tissue sarcoma.

BACKGROUND: The diagnosis of canine soft tissue sarcoma (STS) is based on histological assessment. Assessment of criteria such as, degree of differentiation, necrosis score and mitotic score, gives rise to a final tumour grade, which is important in the recommendation of treatment and prognosis of patients. MATERIALS AND METHODS: Previously diagnosed cases of STS were independently assessed by three board-certified veterinary pathologists. Participating pathologists were blinded to the original results. For the intra-observer study, the cases were assessed by a single pathologist six months apart and slides were randomized between readings. For the inter-observer study, the whole case series was assessed by a single pathologist before being passed onto the next pathologist. Intraclass correlation coefficient (ICC) and Fleiss's Kappa (ƙ) for the intra- (single observer) and inter-observer agreement. RESULTS: Strong agreement was observed for the intra-observer assessment in necrosis score, mitotic score, total score and tumour grading (ICC between 0.78 to 0.91). The intra-observer agreement for differentiation score was rated perfect (ICC 1.00). The agreement between pathologists for the diagnosis and grading of canine STS was moderate (ƙ = 0.60 and 0.43 respectively). CONCLUSION: Histological assessment of canine STS had high reproducibility by an individual pathologist. The agreement of diagnosis and grading of canine STS was moderate between pathologists. Future studies are required to investigate further assessment criteria to improve the specificity of STS diagnosis and the accuracy of the STS grading in dogs.

Inter- and intraobserver agreement in interpretation of CT features of medial coronoid process disease.

OBJECTIVES: To evaluate inter- and intraobserver reliability of the assessment of computed tomography features commonly used in the identification and classification of medial coronoid process disease and to assess inter- and intraobserver variability in the identification of the percentage ulna sclerosis from single transverse computed tomography images. METHODS: Eight observers, on two occasions, reviewed 84 standardised single transverse computed tomography images acquired at the level of the apex of the medial coronoid process. Observers assessed: medial coronoid process disease, coronoid process fragmentation, osteophytes, sclerosis grade and sclerosis delineation with normal bone defined using a sclerometer. Cohen's kappa and intraclass correlation coefficient were calculated. RESULTS: Inter-observer agreement was fair to moderate for identification of computed tomography changes consistent with medial coronoid process disease, moderate to almost perfect for fragmentation, and moderate for osteophyte detection. Agreement was poor for sclerosis grading. Percentage sclerosis measured with a sclerometer had moderate to almost perfect inter- and intraobserver agreement. CLINICAL SIGNIFICANCE: These findings suggest that subjective assessment of computed tomography images is less repeatable than more quantitative methods.

Computed tomographic evaluation of elbow congruity during arthroscopy in a canine cadaveric model.

OBJECTIVE: To assess the effect of arthroscope insertion, using a carbon-fibre rod model, on humero-radial, humero-ulnar and radio-ulnar congruity, as assessed by computed tomography (CT). METHODS: Cadaveric Greyhound elbow joints were assessed at a flexion angle of 135 ± 5° using CT. For condition 1, a 36 mm fulcrum induced cubital valgus, as used to aid arthroscope insertion. For conditions 2 and 3, a single 1.8 or 2.5 mm diameter rod was inserted under arthroscopic guidance to simulate arthroscope position for assessment of the medial coronoid process. Repeat CT scans were obtained for all conditions and parasagittal sections were reconstructed to evaluate medial, axial and lateral positions within the elbow. Humero-radial, humero-ulnar, and radio-ulnar congruity measurements were obtained. Differences between groups were assessed using repeated measures analysis of variance. RESULTS: Mean (±SD) change in radio-ulnar step between conditions 1 and 3 was 0.6 ± 0.3 mm (axial), 0.8 ± 0.6 mm (medial), and 0.5 ± 0.1 mm (lateral). Insertion of rods induced a significant decrease in radio-ulnar step in all planes. Significant differences were also identified between groups for humero-radial, humero-ulnar, and radio-ulnar congruity. CLINICAL SIGNIFICANCE: Insertion of carbon-fibre rods as a model for elbow arthroscope insertion induces elbow incongruity. Changes in radio-ulnar congruity are small but the effect of arthroscope diameter should be considered when assessing elbow congruity.

CT assessment of the influence of dynamic loading on physiological incongruency of the canine elbow.

OBJECTIVES: To present a novel technique for loading of the canine elbow joint and to quantify changes in congruency with increasing load using computed tomography. MATERIALS AND METHODS: Five pairs of thoracic limbs were mounted at a mid stance angle in a custom made jig. Elbow joints were loaded to 0, 33, 66 and 100% of total individual cadaver bodyweight. At each load computed tomography of the elbow was performed. Joint space measurement was performed on sagittal plane central, lateral and medial compartment images at humero-radial (R1 , R2 , R3 ), humero-ulnar (U1 , U2 ) and radio-ulnar loci. The effect of loading on joint spaces was assessed (P<0.05). RESULTS: With increasing load; for central an increase in R1 and radio-ulnar distance and decreased R3 occurred; for medial R1 increased; and for lateral R1 and radio-ulnar distance increased. The largest increases were seen in the lateral compartment. CLINICAL SIGNIFICANCE: Significant changes in humero-radio-ulnar congruency occurred suggesting pronation of the radius with respect to the ulna was induced during loading. This movement may influence the load experienced by the medial coronoid process and could play a role in the aetiopathogenesis of medial coronoid process disease.

A survey of surgical draping practices in small-animal practice in the UK.

Veterinary practices in the United Kingdom were surveyed to compare their surgical draping practices with Royal College of Veterinary Surgeons (RCVS) accreditation tier and other surgery-related factors. Using descriptive statistics and logistic or ordinal regression analysis (where appropriate), the relationships between draping material and accreditation tier and other surgery-related factors were assessed. Procedures were categorised as short or long. Two hundred and sixty-nine surveys were completed. Reusable drapes were used in 66 per cent of practices. Antibiotics were administered routinely in 38 per cent of short and 93 per cent of long procedures. Practices accredited as a Veterinary Hospital (VH) were 6.3-7.2 (short and long surgeries, respectively) times more likely to use disposable drapes, when compared with non-accredited practices. Use of dedicated surgical attire, draping the whole animal/table, and routine antibiotic usage were also positively correlated with disposable drape usage. Fifty-one per cent of practices rated infection rate as most important when choosing drape material. 'Best practice' techniques are associated with lower importance given to infection rate, and higher importance given to financial cost, when choosing drape material. Disposable drape use correlates with RCVS accreditation and with other aspects of surgical technique. Importance ratings awarded correlate with best practice procedures. Clinical relevance 'Best practice' draping procedures, that are not governed by RCVS accreditation scheme, are also more frequently performed in accredited VHs.

Static hydraulic urethral sphincter for treatment of urethral sphincter mechanism incompetence in 11 dogs.

OBJECTIVE: To review the postoperative results and complications associated with urethral sphincter mechanism incompetence managed with a static hydraulic urethral sphincter. METHODS: Case records and a telephone owner questionnaire were retrospectively used to assess postoperative urinary continence scores (1 - dripping constantly to 10 - completely dry) and presence and frequency of complications. RESULTS: Eleven spayed females were included. Median continence score/10 (range) awarded preoperatively was 3 (2 to 6), and scores at two weeks, three and six months were 8 (4 to 10), 9 (4 to 10) and 8 (4 to 10), respectively. At the last survey, the median continence score of 9 (5 to 10) was significantly better (P=0·004) than before surgery. Complete continence was achieved in 36·4% of dogs. The median (range) follow-up time was 412 (118 to 749) days. Complications occurred in 9 of 11 dogs and included dysuria (n=7), bacterial cystitis (n=7), longer urination time (n=8), urinary retention (n=3), haematuria (n=1), pain (n=3) and incisional seroma (n=3). CLINICAL SIGNIFICANCE: Static hydraulic urethral sphincter was frequently associated with minor complications but no major complications (i.e. those requiring further surgery). Continence scores were significantly improved compared with those before surgery, with the possibility of further improvement following inflation of the sphincter.

Phenotypic plasticity, heterochrony and ontogenetic repatterning during juvenile development of divergent Arctic charr (Salvelinus alpinus).

Phenotypic plasticity is a developmental process that plays a role as a source of variation for evolution. Models of adaptive divergence make the prediction that increasing ecological specialization should be associated with lower levels of plasticity. We tested for differences in the magnitude, rate and trajectory of morphological plasticity in two lake populations of Arctic charr (Salvelinus alpinus) that exhibited variation in the degree of resource polymorphism. We reared offspring on diet treatments that mimicked benthic and pelagic prey. Offspring from the more divergent population had lower levels of morphological plasticity. Allometry influenced the rate of shape change over ontogeny, with differences in rate among ecomorphs being minimal when allometric variation was removed. However, plasticity in the spatial trajectory of development was extensive across ecomorphs, both with and without the inclusion of allometric variation, suggesting that different aspects of shape development can evolve independently.

High speed field kinematics of foot contact in elite galloping horses in training.

REASONS FOR PERFORMING STUDY: Mechanical characterisation of the high speed gallop has significant importance for animal welfare and basic biology. Kinematic parameters such as the velocity of each foot at contact can inform theories of why animals gallop, and supplant epidemiological investigation into the mechanisms of musculoskeletal injury. OBJECTIVE: To determine the velocity at which the fore and hind hooves of elite galloping horses impact the surface. METHODS: High speed videography was used to measure the horizontal and vertical velocity of the hoof immediately prior to impact, and the subsequent sink (vertical) and slip (horizontal) distances travelled by the hoof into the surface. Horse speed ranged from 11-19 m/s. In total 170 forelimb and 168 hindlimb foot falls from 89 horses were analysed. RESULTS: Horizontal and vertical hoof velocity increased with speed (P<0.001). Horizontal hoof velocity was significantly greater in the hindlimbs compared to the forelimbs (P<0.001) and was greater in the nonlead limbs compared to the lead limbs (P<0.001). Vertical hoof velocity was significantly greater in the lead limb than the nonlead limb (P<0.001). Overall, forelimbs contacted the ground with a more acute velocity vector angle than hindlimbs (P<0.001). Lead limbs contacted the ground at more acute angles than nonlead limbs (P<0.001). Vertical and horizontal velocities were highly correlated to sink and slip distance. CONCLUSION: Hindlimbs impact the surface at higher velocity than forelimbs, which is likely to result in higher peak impact forces in the hindlimbs. This runs counter to the finding of lower incidence of injury in hindlimbs. POTENTIAL RELEVANCE: Explanations consistent with these findings include the hindlimbs more effectively dampening peak impact forces, or that other injury mechanisms, such as limb vibration and limb load at mid stance, play an important role in injury.

A retrospective study of surgically treated cases of septic peritonitis in the cat (2000-2007).

OBJECTIVES: To review aetiology, clinical signs and outcome of cats surgically treated for septic peritonitis (2000-2007). METHODS: A retrospective study. Inclusion criteria were the identification of intracellular bacteria and degenerate neutrophils and/or a positive culture from abdominal fluid and exploratory coeliotomy. Aetiology, clinical signs, haematological and biochemical parameters, surgical treatment and outcome were recorded and analysed. RESULTS: Twenty-six cats fulfilled the inclusion criteria. Abdominal pain was reported in 10 (38 per cent) and vomiting was reported in 11 (42 per cent) of the cats. The most common aetiology was trauma (31 per cent). The principal source of contamination was the gastrointestinal tract. Hyperlactataemia, hypoproteinaemia and hyperglycaemia were reported in 9, 13 and 14 of the 26 cases, respectively. Non-survivors had significantly higher blood lactate concentrations than survivors (P=0.02). Nineteen cats were managed with primary closure, two with closed suction drains and three with open peritoneal drainage. Twelve (46 per cent) cats survived to discharge. CLINICAL SIGNIFICANCE: In cats, lethargy, depression and anorexia were more common clinical signs than abdominal pain. Lactate level at the time of diagnosis may be a useful prognostic indicator in cats. The proportion of cats that survived was lower than previously reported and owners should be given a guarded prognosis.

High-speed gallop locomotion in the thoroughbred racehorse. I. The effect of incline on stride parameters.

During locomotion up an incline, power is required to elevate the centre of mass. This is provided when the animal's limbs are in contact with the ground. Measurements of stride timing variables from multiple limbs during high speed, over-ground locomotion would enhance our understanding of locomotor powering during changes in terrain. This study measured foot-on and foot-off times from galloping horses using a previously validated system of limb-mounted accelerometers and a global positioning system data logger. A detailed track survey provided incline information from all areas of the track. Measurements were made from six horses over a speed range of 9 to 13 m s(-1). Foot-fall timings were used to calculate variables, which included stance duration, protraction duration, stride frequency and duty factor. The relationship between track incline and measured variables was assessed. Stride variables from horses galloping on level (0-2% incline) and incline (8-12% incline) sections of the track were compared. Fore- and hindlimb protraction durations were significantly reduced across the speed range during incline galloping (P=0.001). This resulted in a mean increase in stride frequency from 2.01 to 2.08 strides s(-1) at 9.5 m s(-1) and 2.10 to 2.17 strides s(-1) at 12.5 m s(-1) during incline galloping. Duty factor was significantly greater for the hindlimbs during incline galloping (P<0.001), increasing from 0.31 to 0.32 at 9.5 m s(-1) and 0.28 to 0.29 at 12.5 m s(-1). Peak limb force was calculated from duty factor and assumed fore- to hindlimb impulse distributions. Smaller peak vertical forces were calculated in the forelimbs and increased peak vertical forces were calculated in the hindlimbs when galloping on an incline. Measured changes in stride timing variables differ from those reported in trotting horses. We propose that horses increase their stride frequency at a given speed during incline galloping to provide power for moving the centre of mass up the slope.

High-speed gallop locomotion in the Thoroughbred racehorse. II. The effect of incline on centre of mass movement and mechanical energy fluctuation.

During locomotion on an incline, mechanical work is performed to move an animal up the slope and increase the potential energy (PE) of the trunk and hence the centre of mass (CoM). Thus, at a given speed the total net mechanical work increases with the PE of the animal. In this study we investigate the mechanical energy (ME) fluctuations and the mechanical cost of transport (MCT) in six horses galloping up a range of gradients. We captured trunk movement with a six degrees-of-freedom inertial sensor mounted over the dorsal spinous process of the fourth to sixth thoracic vertebrae of the horse. Footfall timings were measured using a previously validated system of limb-mounted accelerometers. Speed was measured using a Global Positioning System (GPS) data logger. A track survey provided detailed incline information for the track. Linear (craniocaudal, mediolateral and dorsoventral) and rotational (roll, pitch and heading) kinematic parameters (displacement, velocity and acceleration) were calculated at speeds ranging from 9.0 to 12.0 m s(-1) during routine training over a range of inclines. Estimates of ME fluctuations and the MCT were made. Results showed the effect of incline on trunk motion during galloping was small. Increases in linear mechanical work and MCT were primarily explained by an increase in the work required to move the animal up the slope (and increase the PE of the CoM). Within the stride the majority of the work was performed during hindlimb stance. Our results have provided new insights into how horses power uphill locomotion.

Foraging performance of diet-induced morphotypes in pumpkinseed sunfish (Lepomis gibbosus) favours resource polymorphism.

Morphological plasticity can influence adaptive divergence when it affects fitness components such as foraging performance. We induced morphological variation in pumpkinseed sunfish (Lepomis gibbosus) ecomorphs and tested for effects on foraging performance. Young-of-year pumpkinseed sunfish from littoral and pelagic lake habitats were reared each on a 'specialist diet' representing their native habitat-specific prey, or a 'generalist diet' reflecting a combination of native and non-native prey. Specialist and generalist diets, respectively, induced divergent and intermediate body forms. Specialists had the highest capture success on their native prey whereas generalist forms were inferior. Specialists faced trade-offs across prey types. However, pelagic specialists also had the highest intake rate on both prey types suggesting that foraging trade-offs are relaxed when prey are abundant. This increases the likelihood of a resource polymorphism because the specialized pelagic form can be favoured by directional selection when prey are abundant and by diversifying selection when prey resources are restricted.

The use of MP3 recorders to log data from equine hoof mounted accelerometers.

REASONS FOR PERFORMING STUDY: MP3 recorders are readily available, small, lightweight and low cost, providing the potential for logging analogue hoof mounted accelerometer signals for the characterisation of equine locomotion. These, however, require testing in practice. OBJECTIVES: To test whether 1) multiple MP3 recorders can maintain synchronisation, giving the ability to synchronise independent recorders for the logging of multiple limbs simultaneously; and 2) features of a foot mounted accelerometer signal attributable to foot-on and foot-off can be accurately identified from horse foot mounted accelerometers logged directly into an MP3 recorder. METHODS: Three experiments were performed: 1) Maintenance of synchronisation was assessed by counting the number of samples recorded by each of 4 MP3 recorders while mounted on a trotting horse and over 2 consecutive 30 min periods in 8 recorders on a bench. 2) Foot-on and foot-off times obtained from manual transcription of MP3 logged data and directly logged accelerometer signal were compared. 3) MP3/accelerometer acquisition units were used to log accelerometer signals from racehorses during extended training sessions. RESULTS: Mean absolute error of synchronisation between MP3 recorders was 10 samples per million (compared to mean number of samples, range 1-32 samples per million). Error accumulation showed a linear correlation with time. Features attributable to foot on and foot off were equally identifiable from the MP3 recorded signal over a range of equine gaits. CONCLUSIONS: Multiple MP3 recorders can be synchronised and used as a relatively cheap, robust, reliable and accurate logging system when combined with an accelerometer and external battery for the specific application of the measurement of stride timing variables across the range of equine gaits during field locomotion. POTENTIAL RELEVANCE: Footfall timings can be used to identify intervals between the fore and hind contacts, the identification of diagonal advanced placement and to calculate stride timing variables (stance time, protraction time and stride time). These parameters are invaluable for the characterisation and assessment of equine locomotion.

Testing alternative explanations of character shifts against ecological character displacement in brook sticklebacks (Culaea inconstans) that coexist with ninespine sticklebacks (Pungitius pungitius).

Ecological character displacement (ECD) provides opportunities to test how resource competition generates diversifying selection that results in adaptive divergence. We quantify an association between phenotypic and ecological divergence between two similar small fishes, brook (Culaea inconstans) and ninespine (Pungitius pungitius) sticklebacks, in replicate northern Ontario lakes, Canada. The two species partition resources and habitat, where they coexist, and brooks that coexist with ninespines are more benthically specialized in body form and diet than brooks from local allopatric populations. Here we test various explanations for this pattern. Chance is unlikely to have been the primary cause because divergence is replicated in three separate populations. Preliminary comparisons indicate that resource availability and a variety of abiotic ecological conditions are generally similar between sympatric and allopatric sites, and so do not readily account for the divergence. Biased colonization or extinction is less likely to account for the divergence because character values in sympatry tend to exceed those in allopatry, as expected if they have repeatedly evolved under diversifying selection. Recent studies have also demonstrated that these two species compete, and that competitive effects are more severe for allopatric compared to sympatric brook forms, as predicted if divergence reflects the ghost of competition past. Ongoing studies indicate heritable variation in this system. Our results suggest that even small amounts of character shifts can influence competition and hence relative fitness, further implicating a role for ECD in the evolution of biodiversity.