Phenotypic and genetic trends of patellar luxation in Dutch Flat-Coated Retrievers.

Canine patellar luxation has been described in various dog breeds, with high prevalence especially in smaller dogs. Most dogs suffer from medial displacement of the patella, although in larger dogs lateral displacement is also seen. A sex predisposition has been described for females. Patellar luxation is considered a polygenic, multifactorial disorder. From 1990 to 2007, in total 3834 Flat-Coated Retrievers were screened; 23.6% of those animals were affected with patellar luxation. Lateral displacement of the patella was most common in this breed (61% of cases), whereas medial (31% of cases) and lateral and medial (8% of cases) were less common. Unilateral involvement (51% of cases) was just as often observed as was bilateral involvement (49% of cases). Females were more often affected with patellar luxation (30% of all tested females) than were males (17% of all tested males). The heritability of patellar luxation was 0.17 ± 0.03 in this population, and breeding with one affected parent increased the prevalence of patellar luxation in offspring by 45% compared to that with two unaffected parents. Since the start of the screening program, there was an initial decrease from 28% to 18% in incidence, but this stagnated thereafter. The annual average estimated breeding values followed the same pattern. With approximately one quarter of the Dutch Flat-Coated Retrievers being affected with patellar luxation, this population shows unusually high prevalence compared with reports in other large-breed dogs. The heritability for patellar luxation in this population was moderate (0.17), indicating that environmental factors play a large role in the manifestation of the disorder. A screening program reduced the prevalence of patellar luxation in this breed, but improvement has recently stagnated. Inclusion of breeding values in the screening program could improve its effectiveness.

Syndactyly in a litter of cats.

In this case report, we describe the clinical and radiographic features of a litter of kittens affected with complex syndactyly. We also provide guidelines for the diagnosis, possible treatment and prevention of propagation of this condition. This is the first report of syndactyly in a litter of kittens and syndactyly affecting both the pectoral and pelvic limbs.

Morphological and functional evaluation of a dog with dimelia.

Weight bearing patterns were investigated on a young Cocker Spaniel with dimelia (mirror hand) of the left forelimb, using a pressure sensing walkway (PS walkway). The dog had two left forelimb paws, both originating from the carpus, with symmetrical duplication of metacarpal bones and phalanges. In addition, the left radial head was subluxated and asynchronous growth of the left radius and ulna was noted. The PS walkway demonstrated minimal weight-bearing of the extra (medial) paw and longer metacarpal pad contact of the affected limb. The radiographic changes and the weight-bearing pattern during gait suggested that more weight was loaded on the lateral paw of the affected limb. Treatment was not recommended because of the relatively good limb function and the absence of overt pain. This is the first reported case of canine dimelia and foot pressure patterns in a canine congenital musculoskeletal deformity.

Accuracy of ultrasound-guided intra-articular injections in guinea pig knees.

OBJECTIVE: Dunkin Hartley guinea pigs, a commonly used animal model of osteoarthritis, were used to determine if high frequency ultrasound can ensure intra-articular injections are accurately positioned in the knee joint. METHODS: A high-resolution small animal ultrasound system with a 40 MHz transducer was used for image-guided injections. A total of 36 guinea pigs were anaesthetised with isoflurane and placed on a heated stage. Sterile needles were inserted directly into the knee joint medially, while the transducer was placed on the lateral surface, allowing the femur, tibia and fat pad to be visualised in the images. B-mode cine loops were acquired during 100 µl. We assessed our ability to visualise 1) important anatomical landmarks, 2) the needle and 3) anatomical changes due to the injection. RESULTS: From the ultrasound images, we were able to visualise clearly the movement of anatomical landmarks in 75% of the injections. The majority of these showed separation of the fat pad (67.1%), suggesting the injections were correctly delivered in the joint space. We also observed dorsal joint expansion (23%) and patellar tendon movement (10%) in a smaller subset of injections. CONCLUSION: The results demonstrate that this image-guided technique can be used to visualise the location of an intra-articular injection in the joints of guinea pigs. Future studies using an ultrasound-guided approach could help improve the injection accuracy in a variety of anatomical locations and animal models, in the hope of developing anti-arthritic therapies. Cite this article: Bone Joint Res 2015;4:1-5.

Ex vivo biomechanical comparison of barbed suture and standard polypropylene suture for acute tendon laceration in a canine model.

OBJECTIVES: Evaluate performance and resistance to gap formation of a non-absorbable, barbed, monofilament suture, in comparison with a non-absorbable, smooth, monofilament polypropylene suture, in two different suture patterns: three-loop pulley (3LP) and modified Bunnell-Mayer (BM). SAMPLE SIZE: Seventy-two medium-sized cadaveric superficial digital flexor muscle tendon units. METHODS: After manual transection and suture repair, individual specimens were placed in an electromechanical tensile testing machine and tested to monotonic failure using tensile ramp loading. Video data acquisition allowed evaluation of failure mode and quantification of gap formation. RESULTS: Incidence of gap formation between tendon ends was significantly greater in tenorrhaphies repaired with barbed suture compared to those repaired with smooth polypropylene. Use of a 3LP suture pattern caused significantly less gapping between tendon ends when compared to the BM pattern. CONCLUSION: Smooth polypropylene suture was consistently superior in load performance than a unidirectional barbed suture. The 3LP pattern was more resistant than a BM pattern at preventing gap formation. CLINICAL SIGNIFICANCE: Smooth polypropylene should be recommended over barbed unidirectional suture for use in canine tendinous repair to provide increased resistance to gap formation. The 3LP is superior to the BM suture pattern, requiring significantly more force to cause tenorrhaphy gap formation and failure, which may translate to increased accrual of repair site strength and tendinous healing in clinical situations.

Linear relationship between the volume of hypertrophic chondrocytes and the rate of longitudinal bone growth in growth plates.

In this study, we tested the hypothesis that hypertrophic cell volume varies directly with the rate of longitudinal bone growth. The volume of hypertrophic chondrocytes (using stereological techniques) and longitudinal bone growth per 24 h (using oxytetracycline labeling techniques) were measured in the proximal and distal radial growth plates and the proximal and distal tibial growth plates of 21- and 35-day-old hooded rats and 21- and 35-day-old Yucatan pigs. We demonstrated a high coefficient of correlation (rats 0.98, pigs 0.83) between the final volume of hypertrophic chondrocytes and the rate of longitudinal bone growth over a wide range of growth rates and volumes of hypertrophic chondrocytes. In addition, we demonstrated a positive linear relationship between the rate of longitudinal bone growth and the final volume of hypertrophic chondrocytes. The slope of the regression line was different for rats than for pigs. The relationship was independent of the location of the growth plate in the animal and the age of the animal. The data suggest that mechanisms regulating volume changes in hypertrophic chondrocytes may exist and that chondrocytic volume increase is a major determinant of the rate of longitudinal bone growth. However, the relative contribution of cellular hypertrophy to longitudinal bone growth may be different in rats than in pigs.

Cellular basis of decreased rate of longitudinal growth of bone in pseudoachondroplastic dogs.

Regulation of growth of long bones occurs in cartilage growth plates, where proliferation of chondrocytes, matrix synthesis, and an increase in vertical height in the direction of growth all contribute to the final length of a bone. In this study, we tested the hypothesis that an increase in chondrocytic vertical height is a major variable that accounts for the decreased rate of growth of long bones in Scottish deerhound dogs that had pseudoachondroplasia. The diagnosis of pseudoachondroplasia is based, primarily, on the demonstration of alternating electron-dense and electron-lucent lamellae with a periodicity of 100 to 150 nanometers in dilated rough endoplasmic reticulum. These ultrastructural changes are similar to those seen in humans who have pseudoachondroplasia. In Scottish deerhounds that have the disease, growth of bone is approximately 65 per cent of that in normal animals. There were striking differences in the diameters of proliferating and hypertrophic chondrocytes in pseudoachondroplastic animals compared with normal animals. Specifically, the horizontal diameter of proliferating chondrocytes was 22.7 micrometers in normal animals and 11.3 micrometers in pseudoachondroplastic animals. The vertical diameter of proliferating chondrocytes was 4.8 and 7.6 micrometers in normal and pseudoachondroplastic animals. In the distal 100 micrometers of the hypertrophic zone, the mean horizontal diameter of hypertrophic chondrocytes was 29.6 and 19.1 micrometers and the mean vertical diameter was 22.8 and 18.6 micrometers in normal and pseudoachondroplastic animals. All these differences were statistically significant. The changes in vertical height resulted in a significant difference in the incremental difference in vertical height between chondrocytes from the proliferative and hypertrophic zones in normal animals (18.0 micrometers per chondrocyte) and pseudoachondroplastic animals (11.0 micrometers per chondrocyte). Each chondrocyte in the abnormal plates achieved only 61 per cent of the incremental difference of chondrocytes in normal plates. The mean cellular volume of chondrocytes in the hypertrophic zone was 13,050 cubic micrometers in the normal animals and 10,740 cubic micrometers in the pseudoachondroplastic animals. This difference was not statistically significant. These results are discussed in relation to current theories of the role of the shape and change in volume of chondrocytes in the regulation of longitudinal growth of bone.(ABSTRACT TRUNCATED AT 400 WORDS)

Urinary markers of type I collagen degradation in the dog.

Urinary assays for type I collagen metabolites provide a non invasive index of bone resorption in humans, and are widely used in the management of patients with metabolic bone diseases. The specific aims of this study were to investigate the feasibility of using commercial human assay kits for quantifying the urinary excretion of type I collagen metabolites in dogs of different ages. Urine and serum samples were collected from 35 beagle dogs in five age groups (0 to 1 years; 1 to 2 years; 2 to 3 years; 3 to 7 years; > 8 years old). Urinary concentrations of pyridinoline (Pyd), deoxypyridinoline (Dpd), and the carboxy- and amino-terminal cross-linked telopeptides of type I collagen (CTx and NTx, respectively) were measured with commercial enzyme-linked immunoassay kits. Serum concentrations of another type I collagen metabolite, the carboxy-terminal cross-linked teloptide of type I collagen (ICTP), were measured with a commercial radioimmunoassay. Dilutional studies indicated that the four urinary assays show specific cross-reactivity with canine urine. Age-related differences in urinary marker excretion were identified, with young dogs excreting the highest concentrations of Pyd, Dpd, NTx and CTx. The correlation between the individual urinary markers was excellent (r = 0.87 to 0.98), while the correlation between serum ICTP and individual urinary markers was weaker (r = 0.52 to 0.64). These results validate the usefulness of the commercial assay kits in monitoring type I collagen metabolism in dogs. Histomorphometric studies have confirmed the relationship between collagen degradation and bone resorption in humans, and similar studies are now needed in dogs.

A comparison of two techniques for the determination of serum bone-specific alkaline phosphatase activity in dogs.

Bone-specific alkaline phosphatase (BALP) shows potential as a marker of bone formation in the dog. Recent studies have indicated that serum BALP may provide a useful, non-invasive indicator of skeletal health in dogs, and as a diagnostic and prognostic marker in the management of dogs with musculoskeletal or metabolic disorders. Two assay techniques (one based on wheatgerm lectin precipitation followed by a simple enzymatic reaction, the second on a specific enzyme-linked immunoassay) were used to measure serum levels of BALP in 35 dogs of different ages. As expected, BALP concentrations decreased with age. For the enzymatic assay, mean (+/-SD) serum concentrations of BALP activities were 100.3 (+/-11.6) U/liter in dogs under 1 year of age, 25.3 (+/-6.8) U/L in dogs 1 to 2 years of age, 16.5 (+/-7.3) U/L in dogs 2 to 3 years of age, 14.3 (+/-5.6) U/L in dogs 3 to 7 years of age, and 12.3 (+/-4.8) U/L in dogs aged 8 years and older. Corresponding results from the immunoassay were 56.3 (+/-9.8) U/L, 10.7 (+/-4.5) U/L, 7.0 (+/-2.5) U/L, 6.7 (+/-3.6) U/L and 7.0 (+/-2.9) U/L. There was excellent correlation between the results from the two assay techniques (r = 0. 96; P < 0.0001). The correlation between BALP and total ALP activities was poor (r = 0.20 for enzymatic BALP, r = 0.31 for immunoreactive BALP), indicating that total ALP should be considered unreliable as an indicator of BALP activity in canine serum. The immunoassay demonstrated acceptable (13 per cent) cross-reactivity with the liver isoform of ALP. The commercial immunoassay kit is simple and provides fast results. Although the wheatgerm lectin/enzymatic technique is preferred in situations where the activities of all three isoforms of ALP are required, the immunoassay should be considered whenever the activity of BALP is the focus of interest.

Percutaneous biopsy of the proximal humeral growth plate in dogs.

A percutaneous biopsy technique for the study of endochondral bone formation in the dog was developed. With the dogs under general anesthesia or sedated with a combination of a tranquilizer and a local anesthetic, biopsy specimens were obtained from the proximal growth plate of the humerus with the use of a Jamshidi bone biopsy needle. Biopsy specimens were structurally intact, and contained epiphysis, growth plate, and metaphysis. The procedure proved to be a simple, safe technique, which caused minimal discomfort for the patient and did not affect the growth of the proximal end of the humerus, even after multiple biopsies.

Serum markers of bone metabolism in dogs.

OBJECTIVE: To establish reference values for a panel of serum markers of bone turnover in dogs of various ages. ANIMALS: Dogs in 4 age groups (0 to 1 year; 1 to 2 years; 3 to 7 years; > 8 years). PROCEDURE: Serum concentrations of the carboxyterminal propeptide of type-I procollagen (PICP) and the aminoterminal propeptide of type-I procollagen (PINP), both markers of type-I collagen synthesis (hence, bone formation), were measured by use of commercial human radioimmunoassay kits. Serum concentrations of the carboxyterminal cross-linked telopeptide of type-I collagen (ICTP), a marker for type-I collagen breakdown (hence, bone resorption), also were measured by use of a commercial human radioimmunoassay kit. Serum osteocalcin (OC) concentrations and alkaline phosphatase (ALP) isoenzyme activities were measured by use of techniques developed specifically for dogs. RESULTS: As expected, the highest values for all of the markers were found in young dogs (< 12 months old). Concentrations of OC and ICTP decreased with age, and were lowest in dogs > 8 years old. Total ALP and bone-specific ALP activities initially decreased with age, then increased in dogs > 8 years old. CONCLUSIONS AND CLINICAL RELEVANCE: Serum markers of bone turnover may be useful diagnostic and prognostic tools for management of dogs with musculoskeletal disorders.

Traumatic injury of the iliopsoas muscle in three dogs.

Three dogs with injuries of the iliopsoas muscle were examined. All dogs had a history of trauma. On physical examination, discomfort on hyperextension of the hip joints was detected. Palpation and stretching of the affected muscle by simultaneous internal rotation and extension of the hip joint elicited signs of pain. Abnormalities were not detected on pelvic radiography. On the basis of clinical signs and lack of radiographic abnormalities, a presumptive diagnosis of a strain injury of the iliopsoas muscle was made. Ultrasonography confirmed the presumptive diagnosis and provided further information about the location and extent of the injury. Traumatic injury to the iliopsoas muscle should be included as a differential diagnosis for lameness of the pelvic limb in dogs, and ultrasonography can be of value in the diagnosis of muscle injuries in dogs.

Clinical, radiographic, pathologic, and genetic features of osteochondrodysplasia in Scottish deerhounds.

Clinical, radiographic, pathologic, and genetic features of a form of osteochondrodysplasia in 5 related Scottish Deerhound pups from 2 litters were evaluated. All pups appeared to be phenotypically normal at birth. At approximately 4 or 5 weeks, exercise intolerance and retarded growth were observed. Kyphosis, limb deformities, and joint laxity gradually developed. Radiography of the affected pups revealed skeletal changes characterized by abnormalities in long bones and vertebrae, with involvement of epiphyses, growth plates, and metaphyses. Short long bones and vertebrae and irregular and delayed epiphyseal ossification were most noticeable in younger pups; in older pups, bony deformities became more prominent. In skeletally mature dogs, osteopenia and severe deformities were seen. The histologic changes of the growth plate were compatible with a diagnosis of chondrodysplasia. Growth plate chondrocytes contained periodic acid Schiff-positive, diastase-resistant cytoplasmic inclusions. A single autosomal recessive mode of inheritance was suspected.

Cutaneous T-cell lymphoma in a cat.

An 8-year-old castrated male cat was examined because of a chronic, nonhealing, ulcerative lesion on the left hind limb. Cutaneous lymphoma was diagnosed on the basis of the morphologic appearance of malignant cells and Pautrier's microabscesses on light and electron microscopic examination. The tumor was found to be of T-cell origin by use of a polyclonal antibody recognizing T-cell antigen. Results of serum ELISA for FeLV were negative. The gp70 antigen of FeLV was not detected immunohistochemically in tumor tissue sections, using polyclonal goat antisera and avidin/biotin/peroxidase complex technique. Presence of FeLV was demonstrated by the polymerase chain reaction procedure, involving amplification of a 166-base pair region of FeLV DNA. Although FeLV is reported to be the cause of most types of lymphoma in cats, cats with epitheliotropic cutaneous lymphoma have consistently negative test results for circulating FeLV antigen. In such cases, using the polymerase chain reaction method, tumor DNA may be assessed for integrated FeLV provirus and the presence of FeLV can be confirmed.

Use of two-dimensional real-time ultrasonography for diagnosing contracture and strain of the infraspinatus muscle in a dog.

A strain injury to the infraspinatus muscle was a potential cause of forelimb lameness in a dog. Ultrasonography was used for evaluation of infraspinatus muscle injury. The ultrasonographic appearance of a typical infraspinatus muscle, contracture of an infraspinatus muscle, acute strain of an infraspinatus muscle, and progression of healing of the infraspinatus muscle are described.

[Current viewpoints in mechanisms of bone length growth]. / Nieuwe inzichten in mechanismen van botlengtegroei.

Pertinent morphology and physiology of the growth plate is discussed and theories related to mechanisms of bone length growth are reviewed.