Postnatal modelling of the humeroantebrachial contact areas of radius and ulna in dogs

Necropsy dogs (n = 234) ranging in age between 2 days and 17 years were examined to characterize the cross-sectional shape of the humeroantebrachial contact area of the radius and ulna on radioulnar scans of giant, large, mid-sized, small, and chondrodystrophic breeds. During growth, the contact areas became more circular in shape in all breeds, those in small dogs remained most elliptic. Smallest normalized heights (distance between the tip of the anconeal process and the most proximal aspect of the cranial margin of the radial head = RUH, distance between the tip of the anconeal process and the cranial tip of the medial coronoid process = UH) and depths (distance determined in a right angle to RUH = RUD, distance determined in a right angle to UH = UD) were noted in large and giant breeds with no significant difference between these. In juveniles, a decrease in UD was correlated with a decrease in UH in all breeds as was a decrease in RUD correlated with a decrease in RUH, whereas in non-arthrotic adults this condition could only be proven for mid-sized dogs and small breeds but not for giant, large and chondrodystrophic dogs. The average radioulnar and ulnar heights and depths (as seen in non-arthrotic adults) were calculated to be obtained in mid-sized dogs at least 3-4 weeks earlier than in large dogs. Lipping of the cranial margin of the radial head was significantly (P < 0.001) associated with lesion(s) of the articular surface (i.e. erosion of the articular cartilage and subchondral bone and/or fragmentation of the medial coronoid process) and caused additional change in shape of this contact area, which was then even more circular. However, the variables evaluated (RUH, RUD, UH, UD) allowed only poor discrimination between constitution types and between non-arthrotic and arthrotic joints.     

Demonstration of the articular cartilage of the canine ulnar trochlear notch using high-field magnetic resonance imaging

The articular cartilage covering the ulnar trochlear notch (UTN) of both elbow joints from 25 adult canine cadavers was demonstrated by the use of high-field magnetic resonance imaging (MRI) with a fat-suppressed, three-dimensional, spoiled gradient echo sequence. The dogs used for this study were divided into five groups: giant, large, mid-sized, small, and chondrodystrophic breeds. The distribution of articular cartilage of the UTN was assessed on MR images. The joints were then opened, and the distribution of the articular cartilage of the UTN was verified. In 29/50 joints, there was good agreement between gross findings of the distribution of the articular cartilage of the UTN and MRI interpretation. Reasons for the poor results in small and chondrodystrophic breeds were decreased thickness of the articular cartilage, small size of the articular surface and of its structural features, and the frequent inability to visualize the joint space.     

Canine urolithiasis in Sweden and Norway: Retrospective survey of prevalence and epidemiology

It was estimated that 23 to 24 dogs per 10,000 in Sweden were operated on for urolithiasis between 1956 and 1982. During this period urinary calculi were confirmed in 2898 dogs of 95 breeds, chiefly in chondrodystrophic and well proportioned (not short legged) miniature breeds. The distribution between the sexes in the period 1956 to 1970 was estimated at 57 per cent male and 43 per cent female in the chondrodystrophic breeds, 74 per cent male and 26 per cent female in the well proportioned miniatures, and 83 per cent and 17 per cent female in the large breeds; in the dalmatian (1956 to 1982) 94 per cent were male and 6 per cent female. Urinary calculi were found at a younger age in the chondrodystrophic breeds (1956 to 1970) than in the well proportioned miniature dogs and in large dogs (P<0–001). It was estimated that five dogs per 10,000 in Norway were operated on for urolithiasis between 1956 and 1970. During this period urinary calculi were diagnosed in 71 dogs of 28 breeds. Seventy-nine per cent were male and 21 per cent were female. Urolithiasis in dogs appears to be chiefly constitutionally dependent. Chondrodystrophic breeds and small breeds are particularly susceptible.     

Assessment of the geometry of the cubital (elbow) joint of dogs by use of magnetic resonance imaging

OBJECTIVE: To assess joint geometry and highlight potential evidence of physiologic incongruity in cubital (elbow) joints of large, small, and chondrodystrophic breeds of dogs. SAMPLE POPULATION: Nonarthritic elbow joints obtained from cadavers of mature dogs of large breeds (n = 19), small breeds (14), or chondrodystrophic breeds (8). PROCEDURE: Magnetic resonance imaging was used to quantify interosseous gaps at 6 defined positions and 2 sagittal planes of the humeroantebrachial region by use of a fat-suppressed 3-dimensional gradient-echo sequence. RESULTS: Interosseous gaps in the more medially located sagittal plane were significantly narrower at the level of the anconeal process than at any other position of the joint in large-breed dogs, compared with results for small- or chondrodystrophic-breed dogs. In both sagittal planes, the gaps were significantly wider at the center of the ulnar trochlear notch than at any other position. Significant correlation between body weight and width of the interosseous gaps was found only in large-breed dogs and was found in both sagittal planes at the center of the ulnar trochlear notch (r, 0.834 and r, 0.680, respectively). CONCLUSIONS AND CLINICAL RELEVANCE: In large-breed dogs, the interosseous gap was especially narrow at the level of the anconeal process and its diametric position. This suggests less ability to compensate intra-articular steps in dogs with short ulna syndrome, which predisposes to failure of the union between the anconeal process and olecranon. Geometric incongruity may be regarded as clinically normal in nonarthritic humeroulnar joints. The degree of geometric incongruity increases with body weight.     

Osteological and morphometric observations on intervertebral joints in the canine pre-diaphragmatic thoracic spine (Th1-Th9)

The incidence of facet aplasia was investigated in three groups of pure-bred dogs. We examined large breeds (Rough Collies, Doberman Pinschers, Rottweilers, Bernese Mountain Dogs, German Shepherd Dogs), chondrodystrophic breeds (Dachshunds, Pekinese dogs), and small breeds (Yorkshire Terriers, Maltese dogs). Uni- or bilateral aplasia of zygapophyseal (facet) joints was exclusively found in juvenile and adult small dogs, in which the incidence of aplasia ranged from between 26% (Th1) and 63% (Th8). There was no evidence that aplasia of zygapophyseal joints increases the risk of developing intervertebral disc disease or deformative spondylosis in small breeds. By applying the findings of previous empirical studies on intervertebral disc geometry and its biomechanical behaviour on the present morphometric results, there was an indication that the intervertebral disc may well compensate for the functional loss of aplastic zygapophyseal joints in small dogs. Biomechanical factors and their potential role as inducing agents of facet aplasia in the pre-diaphragmatic thoracic spine are also discussed.     

A morphometric investigation on breed-specific features affecting sagittal rotational and lateral bending mobility in the canine cervical spine (c3-c7)

Vertebral and inter-vertebral parameters obtained in large breeds (n = 74), small breeds (n = 35), and Dachshunds (n = 30) were compared to reveal potential differences in the range of motion of the cervical spine between these three groups of breeds. Body size normalized dimensions of vertebral and inter-vertebral parameters and correlations between these indicate large canine breeds to have a tendency towards higher range of motion in sagittal rotation and lateral bending compared with Dachshunds and small breeds. Higher mobility in large breeds is based on significantly (P < 0.05) lower vertebral endplate heights and widths, shorter vertebral bodies and longer inter-vertebral discs, wider but shorter cranial and caudal articular surfaces, larger differences in width between caudal and cranial joining facets (compared with Dachshunds from C3/4 to C6/7, compared with small breeds from C4/5 to C5/6), and larger differences in length between caudal and cranial joining facets. Large differences in width between caudal and cranial joining facets were associated with small distances between the most medial (C3/4 to C6/7) and lateral (C3/4 to C5/6) aspects of the articular surfaces as well as with small differences in length between caudal and cranial joining facets (C3/4 to C5/6). This suggests that from C3/4 to C5/6 a higher range of motion in lateral bending is coupled to a lower range of motion in sagittal rotation. The present findings contribute also to explain the higher incidence of degenerative lesions of the cervical spine in large dogs.     

Incomplete ossification of the humeral condyle in two Labrador retrievers

Incomplete ossification of the humeral condyle (IOHC) was identified in two Labrador retrievers using computed tomography. Both dogs were non-weightbearing on the affected forelimbs. The dogs were treated by means of a bone screw placed across the humeral condyle. IOHC was originally reported in spaniel and chondrodystrophic breeds. The pathogenesis of the condition remains unknown, but may be related to impaired antebrachial bone growth, similarly to the pathogeneses of elbow dysplasia and radius curvus.     

Gastrointestinal transit of solid radiopaque markers in large and giant breed growing dogs

Observations on food tolerance in dogs have shown that some breeds, especially the giant breeds, have a greater digestive sensitivity. One of the consequences common in these breeds is a higher faecal water content and a poor faecal quality. This could be explained, at least in part, by limited digestive capacity and function in giant breed dogs. In this report, the gastric emptying that represents one parameter of the digestive function was studied in large and giant breed dogs during their growth. Six Great Danes (GD) and six Giant Schnauzers (GS) were fed small radiopaque markers mixed with a test diet at 12, 22 and 36 weeks of age. Abdominal radiographs were made every 30 min for a period of 4 h and then hourly until 12 h. At 12 weeks of age, the gastric emptying pattern was similar in both breeds. However, from 22 weeks of age, the gastric emptying of the GD was significantly more rapid than that of GS. The gastric emptying of small markers tended to slow down in growing dogs, especially in GS. A significant positive correlation between the gastric emptying time of 50% of markers and the body weight was found. These results show that GD have a lower gastric retention time of foods, which could lead to a poor digestion and an altered absorption of nutrients. These could explained why digestive function and sensitivity could be different in dogs from different sizes and breeds.     

Calcium-excess causes subclinical changes of bone growth in Beagles but not in Foxhound-crossbred dogs, as measured in X-rays

Numerous investigations and reports have covered the potential negative effects of an excess of calcium (Ca) in the skeletal development of young dogs. However, it still remains unclear why not all puppies, particularly of larger breeds, develop clinical signs of skeletal disorders after an overexposure to Ca. This trial with the small Beagle breed and a larger Foxhound-crossbred dog (with an adult weight of around 35 kg) investigated the effects of Ca-excess on parameters of bone growth. The employed small breed is known for its chondrodystrophic predispositions, no such data are reported for the slender hound-type Foxhound-crossbred dogs. The Ca-supply had no influence on weight development and general health of the dogs. The measurements of bone lengths and widths in X-rays of the forearm of Beagles and Foxhound-crossbred dogs at 6 weeks of age, and again after a period of overexposure to Ca at about 27 weeks of age, revealed a growth-reducing influence only in Beagles, without influence on clinical parameters of skeletal health.     

RELATIONSHIP OF CERVICAL SPINAL CORD DIAMETER TO VERTEBRAL DIMENSIONS: A RADIOGRAPHIC STUDY OF NORMAL DOGS

Cervical spinal cord abnormalities are often unapparent on myelographic studies, because no normal values for cervical spinal cord diameter are currently available. The purpose of this study was to establish, myelographically, the normal sagittal diameter of the cervical spinal cord in large and small breed dogs and its relationship to the sagittal diameter of the vertebral canal and sagittal height/length of the corresponding vertebral bodies. Forty-one adult dogs underwent cervical radiography and myelography. Spinal cord and vertebral canal sagittal diameter, vertebral body height at C2 to 5, body length at C3 to 5, and dorsal spine length of C2 were measured on lateral views. Ratios of spinal cord:vertebral canal diameter, spinal cord:body height, and spinal cord:body length/spine were calculated, and a normal range was determined for small and large breed dogs. The spinal cord:vertebral canal ratios showed that small breeds have a higher cervical cord-to-canal ratio than large breeds. The mean values and ranges of 14 ratios are reported. The ratios of spinal cord:body length at C2 to 4 in small breeds and spinal cord:body height at C3 to 5 in large breeds were found to be the most accurate for assessing spinal cord sagittal diameter. These normal ranges would allow quantitative and objective evaluation of the cervical spinal cord by myelography and early identification of dogs with altered spinal cord diameter, which could be further evaluated by means of alternative imaging techniques.     

Comparison of the large muscle group widths of the pelvic limb in seven breeds of dogs

Orthopaedic diseases are common in the pelvic limbs of dogs, and reference values for large muscle groups of the pelvic limb may aid in diagnosis such diseases. As such, the objective of this study was to compare the large muscle groups of the pelvic limb in seven breeds of dogs. A total of 126 dogs from different breeds were included, and the widths of the quadriceps, hamstring and gastrocnemius muscles were measured from images of the lateral radiographies. The width of the quadriceps was not different between the breeds, but the widths of the hamstring and gastrocnemius muscles were significantly different between the breeds. The widest hamstring and gastrocnemius muscles were seen in the Rottweilers and the Boxers, respectively. The narrowest hamstring and gastrocnemius muscles were seen in the Belgian Malinois and the Golden retrievers, respectively. All ratios between the measured muscles differed significantly between the breeds. Doberman pinschers and Belgian Malinois had the highest ratio of gastrocnemius width:hamstring width. Doberman pinschers had also the highest ratio of quadriceps width:hamstring width. German shepherds had the highest ratio of gastrocnemius width:quadriceps width. The lowest ratios of quadriceps width:hamstring width were determined in the German shepherds. The ratios of the muscle widths may be used as reference values to assess muscular atrophy or hypertrophy in cases of bilateral or unilateral orthopaedic diseases of the pelvic limbs. Further studies are required to determine the widths and ratios of the large muscle groups of the pelvic limbs in other dog breeds.     

Osteological features in pure-bred dogs predisposing to thoracic or lumbar spinal cord compression

Consistent with those vertebral sites most commonly clinically affected by spinal cord compression, body size normalised midsagittal diameters of the caudal vertebral foramen limits T10-T12 were significantly (P<0.05) lower in Dachshunds relative to other breeds. Minimal midsagittal diameters in Yorkshire Terriers and Maltese were noted at T11cd/12cr. However, these diameters were always larger (P<0.05) in small breeds compared to those in Dachshunds and large breeds suggesting that the small breeds investigated are at lower risk of developing clinical signs if a compressive disease occurs at that site. In large breeds, minimal values were present at L1cd/L2cr and in agreement with clinical findings correlate with those spinal sites most susceptible to spinal cord compression in nonchondrodystrophic large breeds. Caudal displacement of the lumbosacral enlargement of the spinal cord relative to the position previously noted in large breeds was confirmed for the Dachshunds and 50% of small breeds. However, caudal displacement was also noticed in the German Shepherd dogs.     

Congenital elbow dislocations

Three categories of congenital elbow dislocations are described in the literature: humeroulnar, humeroradial, and dislocation or joint laxity with other congenital anomalies. Congenital humeroulnar dislocation is a well-defined problem that occurs predominantly in small breeds of dogs and causes severe limb deformity and dysfunction. Early reduction and stabilization are simple to achieve and have provided good results. Radial head dislocations occur most often as a result of growth disturbance of the radius and ulna. There is a lack of conclusive information on congenital radial head dislocations. Regardless of the etiology, radial head dislocation causes rather mild deformity and lameness and can be treated by conservative management, surgical correction, or radial head ostectomy. Dislocation of the elbow may occur concurrently with other rare congenital anomalies and has been described with ectrodactyly and polyarthrodysplasia.     

Non-dietary risk factors for gastric dilatation-volvulus in large and giant breed dogs

OBJECTIVE: To identify non-dietary risk factors for gastric dilatation-volvulus (GDV) in large breed and giant breed dogs. DESIGN: Prospective cohort study. ANIMALS: 1,637 dogs > or = 6 months old of the following breeds: Akita, Bloodhound, Collie, Great Dane, Irish Setter, Irish Wolfhound, Newfoundland, Rottweiler, Saint Bernard, Standard Poodle, and Weimaraner. PROCEDURE: Owners of dogs that did not have a history of GDV were recruited at dog shows, and the dog's length and height and the depth and width of its thorax and abdomen were measured. Information concerning the dog's medical history, genetic background, personality, and diet was obtained from the owners, and owners were contacted by mail and telephone at approximately 1-year intervals to determine whether dogs had developed GDV or died. Incidence of GDV, calculated on the basis of dog-years at risk for dogs that were or were not exposed to potential risk factors, was used to calculate the relative risk of GDV. RESULTS AND CLINICAL RELEVANCE: Cumulative incidence of GDV during the study was 6% for large breed and giant breed dogs. Factors significantly associated with an increased risk of GDV were increasing age, having a first-degree relative with a history of GDV, having a faster speed of eating, and having a raised feeding bowl. Approximately 20 and 52% of cases of GDV among the large breed and giant breed dogs, respectively, were attributed to having a raised feed bowl.     

Use of biometry and keratometry for determining optimal power for intraocular lens implants in dogs.

Axial length and corneal curvature were determined by use of A-scan ultrasonography and keratometry on both eyes of dogs of various breeds, sizes, and ages. Mean axial length was 20.43 +/- 1.48 mm; axial length was not related to age or sex, but was significantly greater (P = 0.047) in dogs of larger breeds. Mean corneal curvature was 39.94 +/- 2.61 diopters. Dogs of large breeds had significantly (P less than 0.001) flatter corneas. Mild, roughly symmetric astigmatism was detected in a majority of dogs. Use of mean values in a theoretic artificial intraocular lens power equation suggests that aphakic dogs require an implant of approximately 40 diopters to achieve emmetropia.     

Comparison of ultrasonographic characteristics of the thyroid gland in healthy small-, medium-, and large-breed dogs

OBJECTIVE: To determine ultrasonographic characteristics of the thyroid gland in healthy small-, medium-, and large-breed dogs and evaluate the relationships of thyroid gland size and volume with body weight and body surface area (BSA). ANIMALS: 72 dogs of small (6 Toy and 6 Miniature Poodles), medium (12 Beagles), and large breeds (12 Akitas and 36 Golden Retrievers). PROCEDURE: Each dog's thyroid gland was examined ultrasonographically with a 10- to 5-MHz multifrequency linear-array transducer. Size, shape, echogenicity, and homogeneity of thyroid lobes were evaluated on longitudinal and transverse images. Thyroid lobe volume was estimated by use of the equation for an ellipsoid (pi/6 [length x height x width]). RESULTS: Thyroid lobes appeared fusiform or elliptical on longitudinal images and triangular or round to oval on transverse images. In most dogs, thyroid lobes were hyperechoic or isoechoic, compared with surrounding musculature, and had a homogeneous echogenic pattern. Mean length, width, height, and volume of thyroid lobes were significantly greater in Akitas and Golden Retrievers, compared with findings in Beagles or Poodles; mean length, width, and height were significantly greater in Beagles, compared with findings in Poodles. Total thyroid gland volume correlated with body weight (r = 0.73) and BSA (r = 0.74). CONCLUSIONS AND CLINICAL RELEVANCE: Among the dog breeds examined ultrasonographically, thyroid lobe size and volume were more variable than shape, echogenicity, and homogeneity. The correlation of thyroid gland volume with BSA suggests that size of the dog, rather than breed, should be considered when assessing thyroid glands ultrasonographically.     

Incidence of and breed-related risk factors for gastric dilatation-volvulus in dogs

OBJECTIVE: To compare incidence of and breed-related risk factors for gastric dilatation-volvulus (GDV) among 11 dog breeds (Akita, Bloodhound, Collie, Great Dane, Irish Setter, Irish Wolfhound, Newfoundland, Rottweiler, Saint Bernard, Standard Poodle, and Weimaraner). DESIGN: Prospective cohort study. ANIMALS: 1,914 dogs. PROCEDURE: Owners of dogs that did not have a history of GDV were recruited at dog shows, and the dog's length and height and depth and width of the thorax and abdomen were measured. Information concerning the dogs' medical history, genetic background, personality, and diet was obtained from owners, and owners were contacted by mail and telephone at approximately 1-year intervals to determine whether dogs had developed GDV or died. Incidence of GDV based on the number of dog-years at risk was calculated for each breed, and breed-related risk factors were identified. RESULTS AND CLINICAL RELEVANCE: Incidence of GDV for the 7 large (23 to 45 kg [50 to 99 lb]) and 4 giant (> 45 kg [> 99 lb]) breeds was 23 and 26 cases/1,000 dog-years at risk, respectively. Of the 105 dogs that developed GDV, 30 (28.6%) died. Incidence of GDV increased with increasing age. Cumulative incidence of GDV was 5.7% for all breeds. The only breed-specific characteristic significantly associated with a decreased incidence of GDV was an owner-perceived personality trait of happiness.     

A pilot study of sexual dimorphism in the head morphology of domestic dogs

The dog (Canis lupus familiaris) displays more morphological diversity than any other species. It is a direct descendant of the gray wolf (Canis lupus), but shows remarkable behavioral and morphological differences. It has been suggested that differences in skull shape that relate to brain shape and retinal ganglion cell distribution may predict behavioral differences. The aim of this pilot study was to assess head morphology in common breeds for evidence of sexual dimorphism in head length, head width, and the ratio of the 2: cephalic index (CI). When males of 80 breeds studied were compared with females, sexual dimorphism (differences in a t-test at the level of P < 0.01) emerged for head length in 5 breeds, for head width in 10 breeds and in CI for 2 breeds. The 2 breeds that showed sexual dimorphism in CI showed no difference (at the level of P < 0.01) in either length or width. These results suggest that all 3 types of dimorphism in head morphometrics must be considered separately. Although the longer and wider heads in males may be predicted because, within a breed, they are expected to be generally bigger animals, the sexual dimorphism in CI is of interest. It may belie differences in brain shape and even predict differences in health, welfare, and behavior.     

The intra‐ and intertester repeatability of radiographic elbow incongruity grading is high in chondrodystrophic dog breeds

Elbow incongruity is a form of elbow dysplasia that causes osteoarthritis, pain, and lameness, and it is common in chondrodystrophic dog breeds. The objective of this retrospective secondary analysis study was to evaluate the intra‐ and interobserver repeatability of a novel radiographic incongruity grading system for assessing elbow incongruity in three chondrodystrophic dog breeds—the dachshund, Skye Terrier, and Glen of Imaal Terrier. We conducted an observer agreement study that included 220 mediolateral antebrachial radiographs from 110 dogs with the elbow in 90° flexion. The radiographs were independently assessed by three observers at three time points, using a four‐stepped grading scale. The proportion of agreement and Kappa coefficient were calculated. Both the intra‐ and interobserver proportions of agreement were substantial when three grades were required to be identical (.705‐.777 and .609, respectively), and almost perfect for two identical grades (.991‐1.000 and .991, respectively). Some differences in repeatability between breeds were noted; specifically, the intraobserver repeatability was higher in the dachshund, and the interobserver repeatability was lower in the Glen of Imaal Terrier. Our study showed that the radiographic imaging protocol and incongruity grading system have high repeatability when assessing elbow incongruity in chondrodystrophic dog breeds.     

ULTRASONOGRAPHIC EVALUATION OF ADRENAL GLAND SIZE COMPARED TO BODY WEIGHT IN NORMAL DOGS

The accepted cut‐off value for adrenal gland maximum diameter of 0.74 cm to distinguish adrenal gland enlargement in dogs regardless of body weight may not be appropriate for small to medium breed dogs. The purpose of the current retrospective study was to examine adrenal gland dimensions as a function of body weight in healthy dogs in three weight categories (< 10 kg, 10–30 kg, and > 30 kg) representing small, medium, and large breeds, respectively, to establish greater confidence in determining if adrenal gland size is abnormal. The measurements of length (sagittal plane), cranial and caudal pole thickness (sagittal and transverse planes), and caudal pole width (transverse plane) of both adrenal glands were obtained ultrasonographically in clinically healthy dogs (n = 45) with 15 dogs in each weight group. Findings support our hypothesis that adrenal gland size correlates with body weight in normal dogs, and more precise reference intervals should be created for adrenal gland size by categorizing dogs as small, medium, or large breed. The caudal pole thickness of either adrenal gland in a sagittal plane was the best dimension for evaluating adrenal gland size based on low variability, ease, and reliability in measurement.