Variation of actin filament length in dogs.

As the smallest functional unit of force production, the sarcomeres are important in determining muscle function. Actin filament lengths, which are important in determining optimal sarcomere length for a species, have not yet been reported in dogs. This study aims to provide a species-specific value for actin filament length in dogs, while examining intraspecies, intermuscular and intramuscular variations. Muscle samples were taken from the tibialis anterior muscle, the lateral gastrocnemius muscle head and the medial gastrocnemius muscle head in 10 dogs including a Labrador, a Belgian Malinois, a Caucasian Shepherd, German Shepherds and some mixed-breed dogs. Actin filament lengths were determined through transmission electron microscopy. Mean actin filament length across all muscle samples was 0.90 ± 0.01 µm. The low intraspecies variation, combined with a lack of important inter- and intramuscular variation found in this study, affirms the use of a species-specific optimal sarcomere length of 1.89 µm for canine muscles.

Musculotendon excursion potential, tendon slack and muscle fibre length: the interaction of the canine gastrocnemius muscle and tendon.

Although the form-function relation of muscles and tendons has been studied extensively, little in vivo data exist on the musculotendon properties of the gastrocnemius complex in dogs. Using a combination of ultrasound and 3D motion tracking, musculotendon parameters were obtained in vivo from the lateral gastrocnemius muscle and the gastrocnemius tendon in nine healthy Labrador Retrievers. These parameters include musculotendon length and excursion potential, tendon slack length, muscle belly length, muscle fibre length, pennation angle and architectural index. This study also examined the variation of muscle and tendon length contributions to musculotendon length, as well as the relation between musculotendon excursion potential and muscle fibre length or tendon length. To facilitate comparison between dog breeds, the femur length as a potential scaling parameter was examined. In the Labrador gastrocnemius musculotendon complex, the tendon contributes 41% (± 9%) of musculotendon length. In longer musculotendon complexes, the contribution of the muscle belly increases while the tendon contribution decreases. Longer muscle belly and musculotendon complexes were, however, associated with shorter muscle fibres. No significant relations were found between musculotendon excursion potential and muscle fibre length or tendon slack length, and femur length did not prove to be a reliable scale factor for the length-related musculotendon parameters examined in this study. Longer musculotendon complexes exhibit relatively longer muscle bellies, which are in turn associated with shorter muscle fibre lengths. This trade-off between gastrocnemius muscle belly length and muscle fibre length might have the advantage that muscle volume stays constant regardless of the length of the limbs.

A prospective follow up of age related changes in the subchondral bone density of the talus of healthy Labrador Retrievers.

BACKGROUND: During growth, the skeletal structures adapt to the increased loading conditions and mature to a fully-grown skeleton. Subchondral bone density reflects the effect of long-term joint loading and it is expected to change over time. The aim of this study was to describe the long-term changes in the density distribution of the subchondral bone of the talus of healthy Labrador Retrievers in a prospective study. RESULTS: The subchondral bone density distribution was evaluated using computed tomographic osteoabsorptiometry (CTOAM). Visually, all joints showed very similar density distribution patterns. No significant differences in the topography of the density maxima were found between t1 and t2. The mean density, maximum density, and maximum area ratio (MAR) were significantly increased with increasing age. CONCLUSIONS: The subchondral bone density of the talus of healthy Labrador Retrievers increases with increasing age. It is likely an adaptive response of the subchondral bone due to increased joint loading during growth.

Subchondral bone density distribution of the talus in clinically normal Labrador Retrievers.

BACKGROUND: Bones continually adapt their morphology to their load bearing function. At the level of the subchondral bone, the density distribution is highly correlated with the loading distribution of the joint. Therefore, subchondral bone density distribution can be used to study joint biomechanics non-invasively. In addition physiological and pathological joint loading is an important aspect of orthopaedic disease, and research focusing on joint biomechanics will benefit veterinary orthopaedics. This study was conducted to evaluate density distribution in the subchondral bone of the canine talus, as a parameter reflecting the long-term joint loading in the tarsocrural joint. RESULTS: Two main density maxima were found, one proximally on the medial trochlear ridge and one distally on the lateral trochlear ridge. All joints showed very similar density distribution patterns and no significant differences were found in the localisation of the density maxima between left and right limbs and between dogs. CONCLUSIONS: Based on the density distribution the lateral trochlear ridge is most likely subjected to highest loads within the tarsocrural joint. The joint loading distribution is very similar between dogs of the same breed. In addition, the joint loading distribution supports previous suggestions of the important role of biomechanics in the development of OC lesions in the tarsus. Important benefits of computed tomographic osteoabsorptiometry (CTOAM), i.e. the possibility of in vivo imaging and temporal evaluation, make this technique a valuable addition to the field of veterinary orthopaedic research.

Assessment of medial coronoid disease in 180 canine lame elbow joints: a sensitivity and specificity comparison of radiographic, computed tomographic and arthroscopic findings.

BACKGROUND: Diagnostic imaging is essential to assess the lame patient; lesions of the elbow joint have traditionally been evaluated radiographically, however computed tomography (CT) has been suggested as a useful technique to diagnose various elbow pathologies. The primary objective of this study was to determine the sensitivity and specificity of CT to assess medial coronoid disease (MCD), using arthroscopy as gold standard. The secondary objective was to ascertain the radiographic sensitivity and specificity for MCD compared with CT. METHODS: For this study 180 elbow joints were assessed, of which 141 had been examined with radiography, CT and arthroscopy; and 39 joints, had radiographic and CT assessment. Sensitivity and specificity were calculated for CT and radiographic findings using available statistical software. RESULTS: Sensitivity and specificity of CT using arthroscopy as gold standard resulted in high values for sensitivity (100 %) and specificity (93 %) for the assessment of MCD. For the radiographic evaluation, a sensitivity of 98 % and specificity of 64 - 69 % using CT as the technique of reference, were found. DISCUSSION: These results suggest that in case of doubt during radiographic assessment, CT could be used as a non-invasive technique to assess the presence of MCD. CONCLUSION: Based on the high sensitivity and specificity obtained in this study it has been considered that CT, rather than arthroscopy, is the preferred noninvasive technique to assess MCD lesions of the canine elbow joint.

Medial humeral epicondylar lesions in the canine elbow. A review of the literature.

A calcified fragment near the medial epicondyle of the humerus was originally described as an ununited medial epicondyle in 1966. Since then several papers reported similar lesions as a cause of elbow lameness. The aetiology and clinical significance of those lesions is poorly known. This paper gives an overview of the veterinary and human literature in an attempt to explain the aetiology and to suggest a diagnostic protocol and treatment plan.

Comparison of radiography and CT to identify changes in the skulls of four rabbits with dental disease.

Four domestic pet rabbits with dental pathology were presented at a university clinic. In addition to conducting physical examinations of the rabbits, radiographic and computed tomographic (CT) images of the rabbits' heads were obtained. Three rabbits were euthanized at the owners' request, and anatomic sections of the skulls were made. The observations of the anatomic sections, radiographs, and CT images are described. The abnormalities found on the radiographs and CT images were very similar to the findings on the anatomic sections. Compared to radiography, the CT images provided more details about the extent of the dental pathology, which is likely to be important for establishing a more precise prognosis and a more informed decision making process.

The use of CT and CT arthrography in diagnosing equine stifle injury in a Rheinlander gelding.

A 5-year-old Rheinlander gelding was evaluated for left hindlimb stifle lameness. The lameness was localised to the stifle, but source of the lameness was not specifically diagnosed from the physical, radiographic and ultrasonographic examinations. Computed tomography (CT) and CT arthrography were therefore used for further investigation since these imaging techniques image bony structures, cartilage and soft tissues. This examination showed multiple lesions in the stifle: an osteochondrosis dissecans like lesion of the medial femoral condyle, bony fragments, cartilage trauma and caudal cruciate ligament injury. The prognosis for continuing use as a sports horse was regarded as unfavourable. Therefore, the horse was subjected to euthanasia. All CT findings were confirmed by gross pathology. The CT and CT arthrography examination in this case provided a diagnosis not achieved with other conventional imaging techniques.

Elbow lameness in dogs of six years and older: arthroscopic and imaging findings of medial coronoid disease in 51 dogs.

OBJECTIVES: To report on the frequency and distribution of lesions of the medial coronoid process in dogs of six years of age and older, and to describe the arthroscopic findings in the affected joints. To compare those lesions seen in 'old' dogs with those seen in 'young' dogs between the ages of five and 18 months. METHODS: A retrospective study of dogs six-years-old and older admitted for elbow lameness and subsequent elbow arthroscopy. The dogs were divided into groups according to the lesions of the medial coronoid process diagnosed during arthroscopic examination and computed tomography (CT). The radiographic degree of osteoarthritis (OA) and arthroscopically diagnosed lesions on the medial humeral condyle are described. RESULTS: In 51 'old' dogs, five types of lesions could be identified on arthroscopy and CT: chondromalacia-like lesions (2%), fissures (27.5%), non-displaced fragments (12%), displaced fragments (27.5%), and erosions within the medial compartment without fragmentation (31%). A significantly different distribution of lesions was seen in 'young' dogs: fissures (23%), non-displaced fragments (45%), displaced fragments (29%), and erosions within the medial compartment without fragmentation (3%). No difference in radiographic degree of OA was seen between the two groups. CLINICAL SIGNIFICANCE: This study demonstrates the relatively high incidence of medial coronoid disease in dogs older than six years of age, and it highlights one particular problem in 'old' dogs: the complete erosion of the medial compartment.

The effect of patient positioning on adrenal gland linear measurements estimated from computed tomographic images in healthy beagle dogs.

Considering that recumbency can lead to a change in localization, detectability of distinct margins and thus measurement of the organs and reconstruction quality, it is of value to evaluate the effect of positioning on the objective evaluation of abdominal organs in computed tomography (CT). The objective of the present study was to evaluate the effect of patient decubitus on adrenal gland CT biometry. For this purpose, 6 clinically healthy adult beagle dogs underwent CT examination in 4 recumbencies. The various adrenal gland's size measurements were performed by 2 observers. Statistical analyses revealed that repeatability and reproducibility was the highest on the ventral and right lateral recumbencies, respectively. Significant differences were found in the left adrenal gland's length between the different positions (P < 0.001) and the left adrenal gland's width of the cranial pole measured in the dorsal plane (P < 0.04). The measurements on the parasagittal images differed significantly for the left adrenal length (P = 0.01), cranial pole height (P = 0.03), the right adrenal gland's lateral limb's length (P = 0.05) and medial limb's caudal poles height (P < 0.01). The caudal pole height of the right adrenal gland's medial limb was significantly different (P < 0.01) in all positions on the transverse images. In addition, the adrenal position differed significantly, except for the left adrenal gland relative to the nearest renal vessel (P = 0.1). According to these results, it is recommended to perform a CT of adrenal glands always in the same recumbency. If adrenal glands are evaluated on images taken in various recumbencies, we suggest relying on the measurements made on transverse plane images.

Clinical presentation, diagnostic findings, prognostic factors, treatment and outcome in dogs with meningoencephalomyelitis of unknown origin: A review.

Meningoencephalomyelitis of unknown origin (MUO) encompasses a group of idiopathic, most likely immune mediated, inflammatory central nervous system diseases that cause clinical, diagnostic and treatment challenges to veterinary neurologists. Clinical criteria for obtaining this presumptive diagnosis are currently available, and multiple treatment protocols have previously been investigated in small (prospective or retrospective) case series. As this group of diseases is considered fatal if left untreated, the identification of clinically usable prognostic indices could be of great value. This review provides an overview of recent developments in the clinical presentation, diagnostic findings, possible prognostic factors, treatment and outcome in dogs diagnosed with MUO.

Echocardiographic identification of atrial-related structures and vessels in horses validated by computed tomography of casted hearts.

BACKGROUND: Echocardiography is the imaging technique of choice for the equine heart. Nevertheless, knowledge about ultrasonographic identification of dorsally located structures and vessels, related to the atria, in horses is scarce. OBJECTIVES: To describe the echocardiographic approach and the identification of structures and vessels in relation to the atria in healthy horses. METHODS: CT images from two equine hearts, casted with self-expanding foam, were segmented and used to identify atrial-related structures and vessels. These images were compared with standard and nonstandard ultrasound images from ten healthy horses obtained from a left and right parasternal view optimised to visualise the dorsal cardiac area. RESULTS: On new standard ultrasound views, specific atrial anatomical landmarks such as vena cava, pulmonary arteries, intervenous tubercle and oval fossa were identified in all horses. In addition, ultrasound views were defined to visualise the brachiocephalic trunk, pulmonary veins and their ostia. The 3D segmented CT images from casted hearts were used to reconstruct slices that corresponded with the echocardiographic images and allowed correct identification of specific structures. MAIN LIMITATIONS: Ultrasound examinations and casts were from different animals. A small number of casts and horses were used; therefore, anatomical variation or individual differences in identifying structures on ultrasound could not be assessed. CONCLUSIONS: Important cardiac structures and vessels, even the different pulmonary veins, could be identified on standard and nonstandard ultrasound images in adult horses. This knowledge is important to guide and develop interventional cardiology and might be useful for diagnostic and therapeutic purposes.

Single-phase bone scintigraphy in dogs with obscure lameness.

OBJECTIVES: To evaluate the diagnostic merits of scintigraphy in dogs with clinically obscure lameness origin. METHODS: In 43 dogs, the scintigraphic findings were compared with the results of subsequent radiological, computed tomography and/or arthroscopic findings and/or additional neurological examination. RESULTS: In all dogs, focal increased uptake was found in one or more joints or bones. The presence of associated pathology was confirmed by radiography, computed tomography and/or arthroscopy of the limb region of interest. Additional neurological examination was performed when indicated. In cases of elbow pathology, unilateral involvement of the elbow was confirmed with computed tomography/arthroscopy in 14 cases, while bilateral increased uptake could not be confirmed with radiography or computed tomography in three cases. Three dogs showed an increased activity in one joint on the bone scan, while computed tomography, arthroscopy or radiography revealed bilateral joint disease. Generalised mild increased radionuclide uptake in all joints and bones was observed in the lame limb in 15 forelimbs and five hindlimbs. Generalised prominent uptake of an entire limb was noted in three cases suffering from neurological disease. CLINICAL SIGNIFICANCE: Scintigraphy may provide information on areas of increased radionuclide uptake, thereby aiding in the localisation of obscure lameness. Generalised mild increased uptake of radionuclide in all joints and bones in the lame limb may occur in the older dog. The generalised prominent uptake, seen in three cases with neurological disease, may resemble reflex sympathetic dystrophy syndrome seen in human beings.

Hemifacial spasm associated with an intracranial mass in two dogs.

Two dogs were presented with hemifacial spasm. Computed tomography images of both the dogs revealed an intracranial mass. In the first dog, a lesion at the level of the medulla oblongata was thought to cause primary irritation of the facial nucleus, with consequently permanent contraction of the ipsilateral facial muscles. In the second dog, a mass seemingly arising from the middle cranial fossa presumably isolated the facial motor neurons from upper motor neuron control, which resulted in hemifacial spasm as a result of loss of inhibitory interneuronal activity.

Radiographic assessment of the progression of osteoarthrosis in the contralateral stifle joint of dogs with a ruptured cranial cruciate ligament.

The formation and progression of osteoarthrosis in the unaffected contralateral stifle joints of 14 dogs with a unilateral cranial cruciate ligament rupture were monitored radiographically in terms of a global score and the scores for 10 parameters specific for the stifle joint. The dogs were examined initially and six and 12 months later by three observers, and the variability between the observers' scores was also assessed. The score for osteophytes at the tibial attachment site of the ligament was the most reliable parameter, and that for the increase in femoropatellar joint space was the least reliable. In the contralateral stifle joints there were significant increases after six and 12 months in osteophyte formation caudal to the tibial plateau, and in subchondral sclerosis of the tibial plateau and of the long digital extensor muscle groove. These three parameters progressed more regularly during the disease process than the other parameters. The global osteoarthrosis score of the contralateral stifle joint was an important risk factor for sustaining a rupture of the cranial cruciate ligament in that joint during the next six months.

Comparison of subchondral lesion size between clinical and non-clinical medial trochlear ridge talar osteochondritis dissecans in dogs.

In this retrospective study of nine dogs exhibiting bilateral medial trochlear ridge talar osteochondritis dissecans (MTRT-OCD) and unilateral hind limb lameness, we compared subchondral lesion size in limbs with visible lameness, with contralateral lesions that were not associated with any visible lameness. All MTRT-OCD lesions were imaged by radiography and computed tomography (CT). The dimensions of subchondral bone lesions were measured (length, width and depth) using CT software. Similar to a method used in humans, the estimated volume (length x width x depth) and cross sectional area (length x width) were calculated and compared. We found that MTRT-OCD lesions causing visible lameness were significantly larger, and were associated with more joint thickening and degenerative joint disease than contralateral lesions that were not associated with any apparent lameness. As in the disease of shoulder osteochondritis dissecans, there is probably a correlation between the size of MTRT-OCD lesions and the symptoms of lameness.

Diagnostic findings in a lame-free dog with complete rupture of the biceps brachii tendon. A case report in a unilaterally affected working Labrador Retriever.

A case of a complete rupture of the biceps brachii tendon in a lame-free three-year-old Labrador Retriever is described. The dog had a history of chronic lameness following a trauma, but had become lame-free shortly before presentation. Clinical examination, biceps tendon test and shoulder instability tests under general anaesthesia were inconspicuous for shoulder instability. Routine radiographs, arthrography and ultrasound were suspicious for bicipital tendopathy. The definite diagnosis of a complete rupture of the biceps brachii tendon was made upon arthroscopic inspection of the glenohumeral joint.

Spinal Arachnoid Diverticula: Outcome in 96 Medically or Surgically Treated Dogs.

BACKGROUND: Little is reported about the role of medical management in the treatment of spinal arachnoid diverticula (SAD) in dogs. OBJECTIVES: To describe the outcome of 96 dogs treated medically or surgically for SAD. ANIMALS: Ninety-six dogs with SAD. METHODS: Retrospective case series. Medical records were searched for spinal arachnoid diverticula and all dogs with information on treatment were included. Outcome was assessed with a standardized questionnaire. RESULTS: Fifty dogs were managed medically and 46 dogs were treated surgically. Dogs that underwent surgery were significantly younger than dogs that received medical management. No other variables, related to clinical presentation, were significantly different between both groups of dogs. The median follow-up time was 16 months (1-90 months) in the medically treated and 23 months (1-94 months) in the surgically treated group. Of the 38 dogs treated surgically with available long-term follow-up, 82% (n = 31) improved, 3% (n = 1) remained stable and 16% (n = 6) deteriorated after surgery. Of the 37 dogs treated medically with available long-term follow-up, 30% (n = 11) improved, 30% (n = 11) remained stable, and 40% (n = 15) deteriorated. Surgical treatment was more often associated with clinical improvement compared to medical management (P = .0002). CONCLUSIONS AND CLINICAL IMPORTANCE: The results of this study suggest that surgical treatment might be superior to medical treatment in the management of SAD in dogs. Further studies with standardized patient care are warranted.

Phenobarbital or potassium bromide as an add-on antiepileptic drug for the management of canine idiopathic epilepsy refractory to imepitoin.

Imepitoin has recently been approved in Europe for the management of dogs with idiopathic epilepsy. Currently, there is no evidence-based information available on the efficacy of antiepileptic drugs used as additions to the therapeutic regimen in dogs with idiopathic epilepsy that are not well controlled with imepitoin. The goal of this study was to evaluate the efficacy of phenobarbital or potassium bromide (KBr) as add-on antiepileptic drugs for controlling dogs refractory to a maximum dose of imepitoin (30 mg/kg twice daily). The study was performed as a prospective, randomised, controlled clinical trial. The efficacy of phenobarbital and KBr was evaluated by comparing monthly seizure frequency (MSF), monthly seizure day frequency (MSDF), the presence of cluster seizures during a retrospective 2-month period with a prospective follow-up of 6 months, and the overall responder rate. Twenty-seven dogs were included in the study, 14 dogs in the phenobarbital group and 13 dogs in the KBr group. Both median MSF and MSDF decreased in the phenobarbital group (both P = 0.001) and in the KBr group (P = 0.004 and P = 0.003, respectively). Overall, the number of dogs with cluster seizures decreased (P = 0.0005). The responder rate was 79% vs. 69% in the phenobarbital and KBr groups, respectively. We conclude that phenobarbital or KBr add-on treatment decreases median MSF and MSDF in epileptic dogs refractory to a maximum dose of imepitoin. Combination therapy was generally well tolerated and resulted in an improvement in seizure management in the majority of the dogs.

The Influence of the Size, Age and Sex on the Computed Tomographic Measured Size of the Pituitary Gland in Normal Horses.

The objective of this study was to examine the influence of the size, age and sex of the horse on the size of the pituitary gland and determine the possibility of using the pituitary gland height-to-brain area ratio (P:B ratio) to allow comparison of different sized and aged horses. Thirty-two horses without pituitary pars inter-media dysfunction that underwent a contrast-enhanced computed tomographic (CT) examination were included in a cross-sectional study. On the CT images, the pituitary gland height was measured and the P:B ratio was calculated. These measurements were correlated to the size, age and sex of the horses. The pituitary gland height was significantly associated with the size (P < 0.001) and the age (P < 0.001), but not with the sex (P = 0.40), of the horses. No significant association was found between the P:B ratio and the size (P = 0.25), the age (P = 0.06) or the sex (P = 0.25) of the horses. In conclusion, the pituitary gland size varies between different sized and aged horses. The use of the P:B ratio is a valuable metric for making comparisons between the pituitary glands of these horses.