Measuring fluctuating asymmetry in fattening rabbits: a valid indicator of performance and housing quality?

Fluctuating asymmetry (FA) has been advocated as the preferred measure of developmental instability and a reliable indicator of the quality of an animal (performance/fitness) and of its environment during its growing life. Empirical studies, however, are too scant or equivocal to consider this assumption adequately validated, which is partly due to the lack of a robust methodological framework for collecting and analyzing FA data. Therefore, we conducted an experiment in which 306 weaned rabbits were housed either in welfare-friendly pens (n = 6) or barren pens (n = 6). The size of both types of pen was similar (1.91 m2), but the welfare-friendly pens were equipped with suitable enrichment material (gnawing stick, elevated platform, and hiding box) and were stocked with one-half of the number of rabbits compared with the barren pens (17 vs. 34 rabbits per pen). Performance data (BW gain, ADFI, and G:F) were collected every 14 d. After slaughter (d 63 to 72), we measured twice the left- and right-hand side of 11 presumed bilateral traits on intact carcasses and 50 traits on fleshed bones. Using a stringent decision process, an optimal combination of morphological traits for estimating FA in fattening rabbits was determined. This combination consisted of five traits (fleshed bones) that showed no directional asymmetry or antisymmetry and showed a high level of FA relative to the measurement error; also, these traits were not correlated in their signed FA values. Measurements on intact carcasses seemed inappropriate for estimating FA. Using this robust FA measuring protocol, rabbits housed in the welfare-friendly pens were less asymmetric than were rabbits from the barren pens. Except for a greater daily BW gain in the welfare-friendly pens during the first 14 d after weaning, there were no effects of housing conditions on performance traits. The FA was negatively correlated with BW gain in rabbits from the barren pens, whereas in the welfare-friendly pens, there was no correlation. These results support the application of FA as an indicator of animal welfare and performance; however, FA seems to be a more reliable estimator of the underlying developmental instability when living conditions are suboptimal.     

Cage size and enrichment effects on the bone quality and fluctuating asymmetry of fattening rabbits

We studied the effect of increased cage size on different aspects of bone quality (bone strength, diameter, weight, and length) and fluctuating asymmetry (FA). Such characteristics may indicate improved animal welfare, as greater bone quality may decrease fracture incidence during handling, whereas decreased FA has been suggested to signal decreased stress. As stress is likely not only influenced by the quantity of space, but also by its quality, we also studied the effect of environmental enrichment. Groups of 8 rabbits were housed in wire open-top cages of 0.40, 0.46, 0.53, 0.64, 0.80, 1.07, and 1.60 m(2) from weaning until slaughter. All cages of 0.40 and 0.46 m(2) (12 cages/size) were left barren to allow sufficient mobility. One-half of the larger cages were enriched with a wooden-enrichment structure that could be used to gnaw on, hide in, or lie in (6 cages per size × enrichment treatment). Increased cage size led to an increase in tibiofibula diameter (P = 0.008), a tendency for increased tibiofibula weight (P = 0.051), and decreased FA (P = 0.010), suggesting improved welfare. Bone length and strength were not affected by cage size (P > 0.1). Enrichment did not affect FA (P > 0.1), in contrast with our expectations based on previous glucocorticoid analysis. This discrepancy between indicators may be due to sensitivity to other types of stressors or different sensitive periods. In summary, rabbits housed in larger cages had wider, heavier bones, but the absence of changes in bone strength indicate that this is unlikely to result in decreased fracture incidence. In larger cages, FA was lower, suggesting a favorable effect on welfare, whereas no effect of enrichment was shown.     

Asymmetric densitometric and mechanical adaptation of the left fifth metacarpal bone in racing greyhounds

The densitometric and mechanical structural properties of the left and right fifth metacarpal bones of 10 racing greyhounds with a fracture of the central tarsal bone and 10 without a fracture were investigated by dual energy x-ray absorptiometry and a servo-hydraulic materials testing machine. In all the greyhounds the bone mineral density of the left fifth metacarpal bone was significantly greater than that of the right (P<0.001), but there was no significant difference between the degree of asymmetry in bone mineral density in the two groups. The ultimate torque and energy-to-failure of the left fifth metacarpal bone of the greyhounds with a fracture of the right central tarsal bone were significantly higher than in the right fifth metacarpal bone and higher than in both the left and right fifth metacarpal bones of the greyhounds with no fracture (P<0.05). The ultimate torque and energy-to-failure were significantly related to bone mineral density (P<0.005), and 22 per cent of the variation in these structural properties could be explained by variations in bone mineral density. Fifth metacarpal remodelling in response to asymmetric cyclic loading is bone-specific, and structural properties are enhanced in the left fifth metacarpal of greyhounds with a fracture of the right central tarsal bone.     

The morphology and location of atrial specific granules and the demonstration of atrial natriuretic factor in porcine,lapine and bovine heart by immunoelectronmicroscopy

The atrial specific granules (ASGs) were studied in samples collected from the right and left auricles of conventionally slaughtered cows (10), pigs (16) and rabbits (8). In addition, the presence of atrial natriuretic factor (ANF) was detected by immunocytochemistry. Mature ASGs, characterized by the presence of highly osmiophilic and electron-dense material surrounded by a membrane, were present in all atrial myoendocrine cells and their diameters ranged from 100 to 470 nm in pigs, from 100 to 235 nm in cattle, and from 125 to 275 nm in rabbits. Immunoelectronmicroscopical studies revealed the presence of ANF in the ASGs of pigs and cattle, whereas anti-ANF polyclonal serum failed to detect any significative reaction in lapine ASGs. The ultrastructural features of the ASGs of pigs, cattle and rabbits described may be useful in comparing the morphological picture of several cardiac endocrine pathological conditions.     

Symmetry of hip dysplasia traits in the German Shepherd Dog in Australia

Canine hip dysplasia (CHD) is a common and debilitating developmental condition of the canine coxofemoral (hip) joint, exhibiting a multifactorial pattern of inheritance. British Veterinary Association hip traits (BVAHTs) are nine radiographic features of hips used in several countries to ordinally score both the right and left hip of potential breeding candidates to assess their suitability for breeding. The objective of this study was to examine some aspects of the relationship between contralateral scores for each BVAHT in a cohort of 13 124 Australian‐registered German Shepherd Dogs. Goodman and Kruskal gamma coefficients of 0.48–0.95 and correlation coefficients of 0.50–0.74 demonstrate that the association between right and left hip scores varies between moderate and strong for BVAHTs. Principal component analysis of scores detected a sizeable left‐versus‐right effect, a finding supported by symmetry and quasi‐symmetry analyses which found that seven of the nine BVAHTs display significant marginal asymmetry. Dogs showing asymmetry for one BVAHT are significantly more likely to display asymmetry at other BVAHTs. When asymmetry is expressed as a binary trait (either symmetrical or asymmetrical), it displays low to moderate heritability. Estimates of genetic correlations between right and left scores are very high for all BVAHTs (>0.945), suggesting right and left scores for each BVAHT are largely determined by the same set of genes. The marginal asymmetries are therefore more likely to be of environmental and non‐additive genetic origin. In breeding programmes for CHD, we recommend that scores from both hips be used to estimate breeding values, with a term for side‐of‐hip included in the model to account for score variation owing to asymmetry.     

CLINICAL MAGNETIC RESONANCE VOLUMETRY OF THE HIPPOCAMPUS IN 58 EPILEPTIC DOGS*

Hippocampal atrophy, which is a component of hippocampal sclerosis and recognized commonly in human intractable epilepsy, is controversial in canine epilepsy. We examined the hippocampal volume in 58 epileptic dogs and 35 control dogs using magnetic resonance (MR) images, and calculated the relative hippocampal volume asymmetry of the right and left hippocampus. Subjectively, there were visible MR imaging abnormalities in seven of the 58 epileptic dogs (12%). The hippocampel volume asymmetric ratio of epileptic dogs (5.84±4.47%) was significantly greater than that of control dogs (1.62±0.88%). Using a cutoff threshold asymmetric ratio of 6% that is indicated in human epilepsy, 28 epileptic dogs (48%) were characterized as having unilateral hippocampus atrophy. The hippocampal volume asymmetry ratio cannot be used to detect bilateral atrophy. In conclusion, although less frequent than that observed in human epilepsy patients, hippocampal atrophy may occur in canine epilepsy.     

Dynamic mobilisation exercises increase cross sectional area of musculus multifidus

Reason for performing study: In human subjects with back pain, the deep spinal stabiliser m. multifidus is inhibited ipsilaterally leading to atrophy, asymmetry and intervertebral instability. Specific physiotherapeutic exercises are required to reactivate m. multifidus. This study assesses the effect of dynamic mobilisation exercises on size and symmetry of m. multifidus in the equine caudal thoracic and lumbar spine. Hypotheses: Regular performance of dynamic mobilisation exercises over a period of 3 months increases cross sectional area (CSA) and left‐right symmetry of m. multifidus muscles in the caudal thoracic and lumbar spine. Methods: Eight horses performed dynamic mobilisation exercises (3 cervical flexions, one cervical extension and 3 lateral bending exercises to the left and right sides) with 5 repetitions/exercise/day on 5 days/week for 3 months during which time they were not ridden. Left and right m. multifidus CSA was measured ultrasonographically at 6 levels from T10 to L5 at the start (initial evaluation) and end (final evaluation) of the 3 month study. Changes in CSA of the right and left m. multifidus muscles and symmetry of m. multifidus CSA on the right and left sides between the 2 evaluations were sought using analysis of variance (P<0.05). Results: Between the initial evaluation and final evaluation m. multifidus CSA increased significantly at all 6 spinal levels on both right and left sides. Asymmetries in m. multifidus CSA between the right and left sides decreased between the initial and final evaluations. Conclusions: Hypertrophy of multifidus occurred over a 3 month period during which dynamic mobilisation exercises were the only exercise performed. Potential relevance: Dynamic mobilisation exercises maybe a useful rehabilitative technique for horses in which m. multifidus has atrophied in response to back pain.     

Endoscopic evaluation of bronchial morphology in rabbits

OBJECTIVE: To evaluate bronchial morphology endoscopically in rabbits and develop a valid nomenclature for the endobronchial branching pattern. ANIMALS: 10 mature New Zealand White rabbits. PROCEDURES: Flexible bronchoscopy was performed in rabbits anesthetized with isoflurane via nasal mask. Airways were systematically evaluated from the larynx to the terminal branches accessible with a 2.5-mm-outer diameter flexible endoscope. Airway branching patterns were identified and assessed for variation among subjects. RESULTS: Airways of all rabbits were readily examined with the 2.5-mm flexible endoscope. Laryngeal structure and function were normal in each rabbit, and airway branching patterns in all rabbits evaluated were identical. At the carina, branching into left and right principal bronchi was evident. The left principal bronchus divided immediately into the left cranial and left caudal lobar bronchi. The left cranial lobe bronchus further divided into dorsal and ventral segmental bronchi. The left caudal lobe bronchus gave rise to branches originating dorsally, ventrally, and medially before continuing caudally. The right principal bronchus divided into the right cranial, right middle, and accessory lobar bronchi and continued distally as the right caudal lobar bronchus. The right cranial lobe bronchus also divided into dorsal and ventral segmental bronchi, and the right caudal lobe bronchus had branches that originated dorsally, ventrally, and medially. CONCLUSIONS AND CLINICAL RELEVANCE: Definition of a standard nomenclature for airway branching in rabbits will allow precise localization of disease in clinical cases and accurate collection of airway samples in clinical and scientific evaluations.     

Spontaneous neoplasms of lagomorphs.

Many of the same neoplastic processes reported in companion animal medicine have been documented in lagomorphs. With only a few reports in the literature regarding rabbits and hares, the behavior of many of these tumors cannot be predicted. Further, based on limited current knowledge, the practitioner is left to make decisions for diagnostics and therapeutics in these cases based upon current recommendations for companion animals with adjustments for lagomorph physiology. We hope that this review of lagomorph neoplasia will inform the general practitioner of the occurrence of these tumors, promote further documentation and research of these processes in rabbits, and encourage the practitioner of rabbit medicine along with rabbit owners to consult with veterinary oncologists regarding neoplastic processes in rabbits rather than just giving a guarded prognosis.     

The origin and course of the greater,lesser and least thoracic splanchnic nerves in New Zealand rabbits

In this study, the origin and course of the greater, lesser and least splanchnic nerves was investigated in 12 adult New Zealand rabbits with regard to sex and the side of the body. There were no significant differences between the female and male rabbits. The greater and lesser splanchnic nerves were present in all the cadavers examined. However, the least splanchnic nerve was found on the right side in 50% of the cadavers (nos. 2, 4, 6, 7, 11 and 12), and on the left side in 75% (1, 2, 4, 6, 7, 8, 9, 11 and 12). With regard to the origin and pattern of the greater, lesser and least splanchnic nerves, there were significant differences between the right and left sides of the body even in the same rabbit. No significant difference was observed between sexes.     

Horizontal moment around the hoof centre of pressure during walking on right and left circles

Reasons for performing study: Recent research indicates that the digital joints experience some degree of extrasagittal motion during stance and that the moments under the hoof are asymmetric in horses walking in a straight line. On a circle, these have not been defined. Objectives: To quantify the amplitude and symmetry of horizontal twisting moments around the vertical axis through the hoof's centre of pressure on left and right circles at walk. Methods: Six Thoroughbred horses were led at walk across a Kistler force platform on a left and a right circle of 5 m radius. The resultant moment around the hoof was calculated from the 4 horizontal forces and their moment arms. Results: Five of the 6 horses exerted an internal moment around their left forehoof, and 4 exerted an internal moment around their right forehoof on the left circle. On the right circle, 5 of the 6 exerted an internal moment around the left forehoof and a weak external moment around the right forehoof. The moments under the hind hooves were bilaterally similar for right and left circles. Conclusion: Intrahorse variability in the applied moments is low, but there is some interhorse variability, especially in the forelimb moments, that indicates future studies of movements of the distal limb joints should be bilateral to account for mechanical asymmetry. Potential relevance: The finding that horizontal moments vary between forelimbs in some horses will apply to how exercise on a circle is approached, especially in rehabilitation programmes for horses with orthopaedic injury of the distal limb.     

The behavior of superoxide dismutase (SOD) in serum of cows with abomasal displacement (DA)

After surgical reposition of displaced organs (abomasum, uterus, intestines) restoration of blood flow and oxygen supply generates oxygen radicals and other reactive oxygen species. SOD indicates radical stress of the organism. Subject of the study was the question if SOD can be detected in blood serum samples of cows and if there are differences in SOD activity between healthy cows and cows with Dislocatio abomasi (DA). We also wanted to investigate the influence of breed "Schwarzbunte" with DA (16 left/5 rights). The samples were drawn before and 1, 3 and 24 post op. Ten healthy cows of the same breed were also examined (2 weeks and 4-6 weeks after calving). There are no significant differences between the SOD activity of healthy cows and cows with DA, but the SOD activity of cows with left DA is significant lower than the activity of cows with right DA. Post op. SOD activity decreases; 24 h after surgery cows with left but not with right DA show an increase of SOD activity similar to values before surgery. There is a close positive correlation between SOD activity and protein concentration as well as negative correlation to concentration of free fatty acids after surgery. The behaviour of SOD activity shows that the surgical replacement of the displaced abomasum can generate a depression of the antioxidative capacity of the organism.     

The effect of Alkanna tinctoria Tausch on burn wound healing in rabbits

Eighteen adult male New Zealand White rabbits were used in the treatment of partial thickness, severe and olive oil burns. Both right and left sides of the animals were burned to make partial thickness, severe and hot olive oil burn wounds. The solution of A. tinctoria TAUSCH in 16% prepared in medical olive oil in weight basis, were applied to the left, and right side served as control. It was topically applied twice a day by gently rubbing against the burn area. While complete healing of partial thickness and olive oil burn wounds occurred in 7 to 10, and 26 days, respectively, with well formed dermal-epidermal junctions in both groups, severely burned wounds appeared to be nonresponsive to A. tinctoria.     

Are sound dogs mechanically symmetric at trot? No, actually.

A two-year-old, sound Labrador Retriever was determined to be 'right hind limb dominant' by comparison of total hind limb moments of support using inverse dynamics. Net joint moments at the hip, tarsal and meta-tarsophalangeal joints were larger on the right side. Vertical joint reaction forces at the stifle were larger on the right, and horizontal stifle joint reaction forces were smaller on the right. The crus segment was more cranially inclined on the right side through most of stance, but the angle of the resultant stifle joint reaction force vector against the long axis of the crus segment was identical between the right and left sides. The cranially inclined crus segment orientation on one side, coupled with the larger vertical joint reaction force, may result in an internal asymmetry in stifle joint mechanics, although the effects of this on cruciate ligament stresses remain to be determined.     

Gene expression profiling in embryonic chicken ovary during asymmetric development

The reproductive system in female birds arises as bilateral asymmetrical anlagen, excluding the birds of prey. Earlier, histological and messenger RNA (mRNA) expression profile studies of several genes related to gonadal sex differentiation in chicken embryos tried to elucidate the query of this asymmetry in a scattered manner. To understand the matter precisely, we have focused on mRNA expression of a cohort of genes (FSHR, CYP19A1, caspase 3, caspase 8) in second half of the embryonic days (E10–E18). The established role of leptin in development of the embryo and its expression in the embryonic ovary also drove us to check leptin receptor (LEPR) expression in the ovary. Increased expression of FSHR and CYP19A1 in the left ovary compared with that in the right ovary was identified (P < 0.05), promoting preferential left ovarian development and functionality. Significant high expression (P < 0.05) of the apoptotic genes in the right ovary were also involved here. Leptin probably has no direct influence on ovarian asymmetry as no significant variation in gonadal mRNA expression of LEPR was observed within the same experimental days. We propose that asymmetric expression of this cohort of genes (FSHR, CYP19A1, caspase 3, caspase 8) leads to the development of dimorphic gonads during embryogenesis.     

Relationships between lactational incidence of displaced abomasum and milk production traits in German Holstein cows

The objective of this study was to analyse the heritabilitiy of the lactational incidence of displaced abomasum (DA) and the relationships of DA with milk production traits in German Holstein cows. Data were recorded between February 1999 and January 2000 in cooperation with five veterinary practitioners. Their veterinary practices were located in the northern part of Lower Saxony. The investigation included 160 dairy farms under the official milk-recording scheme with 9,315 cows. The lactational incidence of the left abomasal displacement amounted to 1.21%, and of the right abomasal displacement to 0.41%, respectively. The linear heritability estimates for the lactational incidences of left and right DA were h(2) = 0.05 +/- 0.012 and h(2) = 0.004 +/- 0.005, respectively. Using the Dempster-Lerner-transformation the corresponding heritabilities were h(2) = 0.53 and 0.09, respectively. Milk losses for the lactation when DA was diagnosed were significant and reached 1016 kg milk, 41 kg fat, 36 kg protein and 0.07% protein. Fat content significantly increased by 0.18%. The analysis could not show significant differences between cows diagnosed with DA and cows not diagnosed with DA in the 305-day milk production traits of the lactation preceding the diagnosis of DA. There was also no indication for an unequal distribution of breeding values for milk performance traits between cows with and without DA. The additive genetic correlations between 305-day milk performance and left DA were low. The results indicated that cows with a high milk production and superior breeding values for milk performance were not exposed to an increased risk for DA.     

Los ligamentos triangulares del perro

The triangular ligaments of 82 dogs were studied to determine the presence, number, size and hepatic attachment of each ligament. A new — dorsal or intermediate — ligament is described. The left ligament was found to be the largest and the only constant one. It could be simple, double or triple. The right and intermediate ligaments could be simple or double. The frequency of these types of ligaments and the variations of them are considered. There was a statisticaly significative difference between the dimensions of the left and right ligaments specially when the left was simple     

Variation in conformation in a cohort of National Hunt racehorses

REASONS FOR PERFORMING THE STUDY: Assessment of conformation is commonly used in the selection of horses for performance purposes. Little information is available on the normal range of conformational traits within the Thoroughbred population. OBJECTIVES: To describe variations in conformation in a cohort of racing Thoroughbreds in order to provide a set of baseline standards within which conformational traits can be considered normal. MATERIALS AND METHODS: Ninety-eight conformational parameters were measured in a cohort of 108 National Hunt racehorses using a digital motion analysis system. The measurements consisted of segment lengths, joint angles in 2D and 3D, inclinations, deviations and circumference measurements. The differences between left and right sides were determined to obtain a measure of asymmetry. Conformational parameters were related to each horse's country of origin, preferred race distance and race type. RESULTS: The majority of parameters followed a normal distribution with the biggest relative variation in hoof related measurements and in stifle and coxal angle. All circumference measurements and the majority of the length measurements were significantly correlated with the height of the horse at the withers. No underlying pattern of combinations of conformational parameters was identified. Twenty-five per cent of the parameters showed a significant difference between left and right-sided measurements. A significant difference in girth and intermandibular width was observed between Irish and French horses. CONCLUSIONS: Thoroughbreds differ from other breeds, not only with regard to segment lengths but also with regard to joint angles and deviations. Variation in conformational parameters was relatively small and no distinct pattern of combinations of conformational traits identified. CLINICAL RELEVANCE: The variation in conformational measurements in Thoroughbred racehorses establishes a set of baseline measurements of conformational range against which individual horses can be assessed.     

Ultrasonographic measurement of the adrenal gland-to-abdominal aortic ratio as a valuable method of estimating normal adrenal size in rabbits

A wide range has been reported for the ultrasonographic measurements of the normal adrenal gland in rabbits. Therefore, having sufficient information about the normal measurements of the adrenal gland and their relationship with indicators such as weight, sex and the diameter of the internal abdominal aorta will be of great help in diagnosing diseases of the adrenal gland. In the present study, 21 healthy adult intact rabbits were selected. The abdominal cavity of the animals was examined using ultrasound; adrenal gland parameters such as length, width, height, circumference and area on the right and left sides were measured in both sagittal and transverse planes. Additionally, the diameter of the abdominal aorta in the sagittal plane was imaged. After statistical analysis, the parameters of the adrenal glands on the right and left showed a positive significant correlation with the weight and the diameter of the abdominal aorta, although no significant correlation was found between these parameters and sex. The ratio of adrenal gland parameters to abdominal aortic diameter was calculated and the statistical analysis of the values showed that, except for the ratio of left adrenal area to aortic diameter, the other ratio of adrenal gland parameters to abdominal aortic diameter was not significantly related to weight. Therefore, these ratios can be used as suitable indicators for assessing the change in size of the adrenal gland of rabbits of different sizes. Knowing the relationship between normal adrenal measurements and the indices such as weight, sex and diameter of the abdominal aorta can help clinicians and researchers evaluate the changes in the size of the adrenal gland.     

Live animal measurement of carcass traits by ultrasound: assessment and accuracy of sonographers.

The establishment and evaluation of an assessment system to accredit sonographers for measuring the carcass traits of subcutaneous fat depths and longissimus muscle area (LMA) on potential breeding animals by real-time ultrasound is described. Repeatability of operators, variation between the animal's left and right sides, and variations in technique were assessed from measurements and repeat measurements of 30 cattle by up to eight operators at three testing sessions. Accuracy of carcass data was determined by repeatability of measurements, variability between measurers, between left and right sides of the carcass, and variation due to handling and dressing procedures. Correlations with carcass data averaged .92 for rump fat, .90 for rib fat, and .87 for LMA. Residual SD averaged .81 mm, .88 mm, and 5.1 cm2. A very experienced sonographer can measure LMA only marginally less accurately than it can be measured on the carcass. In Session 3, the SE between repeat fat measurements for accredited sonographers averaged .43 mm, indicating that fat depths can be measured more accurately, but when comparing measurements from different operators, adjustments may be required for differences in technique, otherwise overall accuracy will be about the same, approximately 1 mm. Scanned rump fat measurements were consistently approximately 20% higher than on the chilled, hanging carcass 24 h after slaughter; after applying the standard correction factor of 1.17, LMA measurements were similar. Scan and carcass rib fat measurements were similar for animals with less than or equal to 10 mm of fat cover, above which carcass measurements tended to be higher.