Comparison of the Role of the Subcutaneous Tissues in Cutaneous Wound Healing in the Dog and Cat

OBJECTIVE

To describe and compare the contribution of the subcutaneous tissues to 1st and 2nd intention cutaneous wound healing in the dog and cat.

STUDY DESIGN

Experimental study.

ANIMALS

Domestic shorthaired cats (n=6) and 6 beagle dogs.

METHODS

Paired wounds were created on either side of the dorsal midline; the subcutaneous tissue was removed on 1 side and left intact on the other. Square, open wounds of the dorsal aspect of the thorax were observed for 21 days to monitor granulation tissue formation, wound contraction, epithelialization, and total healing (contraction+epithelialization). Breaking strength of sutured linear wounds was measured 7 days after wounding. Laser-Doppler perfusion imaging (LDPI) was used to measure cutaneous perfusion.

RESULTS

First intention healing: subcutaneous tissue removal had no consistent effect on sutured wound strength at 7 days in dogs or cats. Second intention healing: removal of subcutaneous tissue reduced wound perfusion, granulation, contraction, epithelialization, and total healing. Granulation tissue formation and wound contraction were delayed to a significantly greater degree in cats than in dogs (P<.05). Two dogs (33%) had minor wound infections.

CONCLUSIONS

The subcutaneous tissues make an important contribution to 2nd intention cutaneous healing. Dog and cat wounds had delayed 2nd intention healing when subcutaneous tissues were removed; wounds in dogs, but not cats, had largely recovered from this delay by 21 days.

CLINICAL RELEVANCE

Extensive debridement of subcutaneous tissue may delay wound healing particularly in feline patients. A higher risk for wound infections may accompany extensive removal of subcutaneous tissues in dogs.

Synovial Membrane Microarthroscopy of the Equine Midcarpal Joint

OBJECTIVE

To evaluate the value of microarthroscopy in the equine midcarpal joint using the vital stains methylene blue, trypan blue, neutral red, and Janus green B to observe components of the synovial lamina propria, vascular architecture, and synoviocytes.

STUDY DESIGN

Experimental.

ANIMALS

Ten horses.

METHODS

Microarthroscopy of left and right midcarpal joints was performed with and without vital staining of the synovium. Four vital stains (methylene blue, trypan blue, neutral red, and Janus green B) were evaluated, with each stain used in 5 joints. Synovial biopsy specimens were collected from the dorsomedial and dorsolateral aspects of the joint.

RESULTS

All dyes were biocompatible. At x 60 without vital staining, synovial surface topography, vascular network, and translucency were observed. Intra-articular vital dyes improved evaluation of synovial surface topography. At x 150 with vital staining, individual synoviocytes were clearly identified with all dyes, except neutral red. Although methylene blue provided the best in vivo microscopic differentiation of the structure of the intima, trypan blue had superior retention in conventionally processed synovial biopsies.

CONCLUSIONS

Methylene blue, trypan blue, neutral red, and Janus green B stains can be used safely for microarthroscopy. Good visualization of cells and vascular network can be obtained by microarthroscopy, and microarthroscopic evaluation of the synovium compares favorably with conventional histologic evaluation of biopsy specimens.

CLINICAL RELEVANCE

Microarthroscopy may be beneficial in both research and clinical diagnosis of equine articular diseases.

Cutaneous Wound Healing in the Cat: A Macroscopic Description and Comparison with Cutaneous Wound Healing in the Dog

OBJECTIVE

To describe the macroscopic features of first and second intention cutaneous wound healing in the cat and compare with the dog.

STUDY DESIGN

Experimental study.

ANIMALS

Domestic shorthaired cats (6) and beagle dogs (6).

METHODS

Square, open cutaneous wounds created on the dorsal aspect of the thorax were evaluated for 21 days for temporal and spatial development of granulation tissue, wound contraction, epithelialization, and total healing. To evaluate first intention healing, breaking strength of sutured linear cutaneous wounds was measured at 7 days post-wounding. Laser-Doppler perfusion imaging was used to measure cutaneous perfusion.

RESULTS

First intention healing: sutured wounds in cats were only half as strong as those in dogs at day 7 (0.406 versus 0.818 kg breaking strength). Second intention healing: cats produced significantly less granulation tissue than dogs, with a peripheral, rather than central distribution. Wound epithelialization and total wound healing (total reduction in open wound area from contraction and epithelialization) were greater for dogs than for cats over 21 days. Wound contraction on day 7 was greater for dogs, but not on day 14 or 21. Cutaneous perfusion was initially greater for dogs than for cats, but no differences were detected after day 7.

CONCLUSIONS

Significant, previously unreported differences in cutaneous wound healing exist between cats and dogs. In general, cutaneous wounds in cats are slower to heal. Cats and dogs also appear to use different mechanisms of second intention healing. In cats wounds close mainly by contraction of the wound edges, whereas in dogs wounds close more from central pull, and epithelialization.

CLINICAL RELEVANCE

Surgeons should view the cat as a unique species, which presents its own special challenges in wound healing, and should take this into account when planning treatment of feline wounds, either by primary closure, or by second intention healing.

In retrospect: teaching is "dribbling and passing"

An introspective view of the author revealed that his philosophy, style, and methods of teaching were anchored in the broad fundamentals of considering, organizing, and implementing an educational plan. Key elements of these fundamentals included the art of teaching, time management and the commitment of time to students, experience and repetition, teaching methodology, communication and listening, relevancy of information, the laboratory teaching environment, and the responsibilities of students. A coherent approach to teaching was developed by blending these individual elements with a commitment to learning by all students.

Influence of dietary calcium and phosphorus content in a fixed ratio on growth and development in Great Danes

OBJECTIVE

To study the musculoskeletal development of Great Dane puppies fed various dietary concentrations of calcium (Ca) and phosphorus (P) in fixed ratio by use of dual energy x-ray absorptiometry (DEXA), determination of serum insulin-like growth factor 1 and parathyroid hormone concentrations, radiography, and blood chemistry analysis results.

ANIMALS

32 purebred Great Dane puppies from 4 litters.

PROCEDURE

At weaning, puppies were assigned randomly to 1 of 3 diets. Blood was collected for biochemical analyses and hormone assays, and radiography and DEXA were performed through 18 months of age. Changes in body weight, bone mineral content, fat tissue weight, lean mass, result of serum biochemical analyses, hormonal concentrations, and radius lengths were analyzed through 18 months of age.

RESULTS

Bone mineral content of puppies correlated positively with Ca and P content of the diets fed. Significant differences between groups in bone mineral content, lean mass, and body fat were apparent early. The disparity among groups increased until 6 months of age and then declined until body composition was no longer different at 12 months of age. Accretion rates for skeletal mineral content, fat, and lean tissue differed from each other and by diet group.

CONCLUSIONS AND CLINICAL RELEVANCE

Ca and P concentrations in the diet of young Great Dane puppies are rapidly reflected in the bone mineral content of the puppies until 5 to 6 months of age, after which hormonal regulation adjusts absorption and excretion of these minerals. Appropriate Ca and P concentrations in diets are important in young puppies < 6 months of age.

Distribution of beta-endorphin and substance P in the shoulder joint of the dog before and after a low impact exercise programme

Beta-endorphin and substance P were immunolocalized in the articular cartilage, synovial membrane and fibrous joint capsule of dogs. Twelve adult greyhounds were randomly assigned to one of three groups: control, limited exercise, or regimented exercise. On day 0, biopsies of articular cartilage and joint capsule were obtained from the left shoulder joints of dogs receiving limited and regimented exercise. On day 72, biopsies of joint capsule from right and left shoulders and articular cartilage from the right shoulder joint were analysed for the presence of glycosaminoglycans (GAG) and for immunolocalization of substance P and beta-endorphin. Regimented exercise increased the presence of GAGs and immunolocalization of substance P and beta-endorphin in articular cartilage and synovial membrane compared to day 0 biopsies and untreated controls. Localization of beta-endorphin became prominent in and around the chondrocytes. Substance P was increased in chondrocytes and extracellular matrix. Concomitant changes in localization of beta-endorphin and substance P may have a role in the modulation of the microphysiological environment, metabolism, or function of joint tissues in response to low-impact exercise.

Evaluation of the rat stifle joint after transection of the cranial cruciate ligament and partial medial meniscectomy

Osteoarthritis (OA) was induced in the rat stifle joint by partial medial meniscectomy (PMM) and transection of the cranial cruciate ligament (CCL). At 10 weeks after destabilization, joint morphologic and pathologic changes were observed, scored, and compared. The intact rat stifle joint was observed in a mid-saggital plane. Articular cartilage of the distal portion of the femur and proximal portion of the tibia had thicker and thinner sites, and the thicker sites were located caudally on the distal portion of the femur and centrally on the proximal portion of the tibia. The two separate triangular portions of the medial meniscus observed in the mid-saggital plane contained a center of ossification in the cranial portion and fibrocartilage in the caudal portion. The synovium was one to three cells thick, and contained rare inflammatory cells. Although lesions were more severe in stifles after PMM, both treatments produced OA lesions that closely simulated OA lesions of other species. Lesions consistent with idiopathic OA included chondrocytic clones with increased metachromasia around them, chondrocytic death, loss of metachromasia, fibrillation, fissuring, erosion of articular cartilage, osteophyte formation, and variable synovial inflammation. The results indicate that PMM and CCL transection in the rat are useful in vivo models for study of the etiopathogenesis of OA and therapeutic efficacy of anti-arthritic drugs and treatment concepts.

Oral treatment with a nutraceutical (Cosequin) for ameliorating signs of navicular syndrome in horses

Fourteen horses with a progressive forelimb lameness of 3 to 12 months' duration, diagnosed as navicular syndrome, were selected from clinical cases admitted to Auburn University Equine Hospital for evaluation of the efficacy of an orally administered nutraceutical (Cosequin, Nutramax Laboratories, Inc., Edgewood, MD) for ameliorating clinical signs associated with naturally occurring navicular syndrome. Horses were randomly allocated to treatment with the nutraceutical or a placebo. Treatment was five scoops (16.5 g) of powder twice daily in the feed. The test group (n = 8) received a patented nutraceutical consisting of 9 g of FCHG49 (a highly purified glucosamine HCl), 3 g of TRH122 (a specific purified low-molecular-weight sodium chondroitin sulfate), and 600 mg of manganese ascorbate. The placebo group (n = 6) received an indistinguishable oral powder containing only excipients. Owners and the investigator were unaware of group assignments. The same investigator assessed lameness and overall clinical condition at enrollment and after 4 and 8 weeks of treatment. Lameness was assessed by an algofunctional lameness index, comprising a combined sum score of standing posture, hoof tester examination, and lameness scores at various levels of work. Overall clinical efficacy was rated on a visual analogue scale. Owners assessed lameness via a preassigned questionnaire, incorporating an algofunctional lameness index and overall clinical condition at weekly intervals. Radiographic examinations of the navicular bones were performed at enrollment and after 8 weeks of treatment. The median algofunctional lameness index and overall clinical condition scores assigned the investigator were significantly improved (P = .05) for horses treated with the nutraceutical compared with placebo-treated horses. The degree of improvement in algofunctional lameness index assigned by owners after 8 weeks was also significant (P = .045) between the treatment groups. Radiographic scores after treatment were not significantly different between the groups (P > .05).

Immunolocalization analysis of transforming growth factor-beta1 in the growth plates of broiler chickens with high and low incidences of tibial dyschondroplasia

Immunolocalization of transforming growth factor-beta1 (TGF-beta1) was determined in growth plates of two lines of broiler chickens with low and high incidences of tibial dyschondroplasia (TD). Ultrathin sections of growth plates from each line were treated with a polyclonal antibody specific for TGF-beta1, followed by colloidal gold-labeled protein A. Immunolocalization for TGF-beta1 was observed in chondrocytes of all zones of growth plates of low and high TD incidence lines. However, immunolocalization in extracellular matrix was restricted to the hypertrophic zones of both lines. In the hypertrophic zone of low TD incidence line, immunolocalization of TGF-beta1 in the extracellular matrix adjacent to collapsed cartilage canals (matrix streaks) was significantly greater than immunolocalization between patent cartilage canals. A similar increase was not observed in the high TD incidence line. Results indicate that chondrocytes of all zones of the growth plate contain TGF-beta1 but do not release it into extracellular matrix until hypertrophy has occurred. Greater concentrations of TGF-beta1 adjacent to collapsed cartilage canals may play a role in controlling angiogenesis and directing invasion of mineralized hypertrophic cartilage by metaphyseal blood vessels. A low concentration of TGF-beta1 in the extracellular matrix adjacent to collapsed cartilage canals of the high TD incidence line may be a factor in limiting vascular invasion of dyschondroplastic cartilage of TD lesions.

Low-field magnetic resonance imaging of the equine tarsus: normal anatomy

The objective of this study was to define the normal gross anatomic appearance of the adult equine tarsus on a low-field magnetic resonance (MR) image. Six radiographically normal, adult, equine tarsal cadavers were utilized. Using a scanner with a 0.064 Tesla magnet, images were acquired in the sagittal, transverse and dorsal planes for T1-weighted and the sagittal plane for T2-weighted imaging sequences. Anatomic structures on the MR images were identified and compared with cryosections of the imaged limbs. Optimal image planes were identified for the evaluation of articular cartilage, subchondral bone, flexor and extensor tendons, tarsal ligaments, and synovial structures. MR images provide a thorough evaluation of the anatomic relationships of the structures of the equine tarsus.

Effects of dietary roxarsone supplementation, lighting program, and season on the incidence of leg abnormalities in broiler chickens

Two 4 x 2 factorial experiments were designed to test the effects of four diets, differing in anticoccidial programs and roxarsone (3-nitro-4-hydroxyphenylarsonic acid) content, and two lighting programs on the incidence of leg abnormalities in 56-d-old male and female broiler chickens. The four diets were: A) basal diet + salinomycin (60.0 g/ton); B) basal diet + salinomycin (60.0 g/ton) + roxarsone (45.4 g/ton); C) basal diet + roxarsone (45.4 g/ton) + live coccidial vaccine; and D) basal diet + live coccidial vaccine. The light treatments were: 1) restricted (R) [18 h light (L): 6 h dark (D)] and 2) standard (S) [23L:1D]. The respective experiments were conducted during winter (Experiment 1, November to January) and summer (Experiment 2, June to August) growing conditions in the southeastern U.S. Light treatment had no significant (P > 0.10) effect on the incidence of leg abnormalities in either experiment. However, in Experiment 1, there was a light treatment by sex interaction; leg abnormalities were greater for males on Treatment R than Treatment S. In Experiment 2, females had a higher incidence of leg abnormalities than males (8.29 vs 4.73%). There was a diet by sex interaction for the incidence of leg abnormalities in Experiment 2; females had a greater incidence of leg abnormalities than males on Treatment A. In both experiments, the incidence was greater with dietary treatments containing roxarsone (P < 0.10). The percentage of leg abnormalities was greater in Experiment 2 than Experiment 1. Leg abnormalities were primarily due to fibrosis of the gastrocnemius tendons and tendon sheaths.

Effect of hydration on signal intensity of gelatin phantoms using low-field magnetic resonance imaging: possible application in osteoarthritis

Five gelatin phantoms were constructed to study the effect of matrical hydration on magnetic resonance imaging (MRI) signal intensity using a low-field strength imager. Water content of the phantoms ranged from 75 to 95% weight/weight. Signal intensity values of each phantom were measured using five imaging sequences: proton density, T1-weighted, T2-weighted, inversion recovery with short inversion time, and inversion recovery with long inversion time. There was significant positive correlation (p < .05) of signal intensity with differences in hydration using the T2-weighted sequence and the inversion recovery sequence with short inversion time. Significant negative correlations (p < .05) were found with T1-weighted imaging and the inversion recovery sequence with long inversion time. In a second part of the study, in vivo focal variations in MRI signal intensity were evaluated in a canine cranial cruciate ligament deficient model of osteoarthritis. Signal intensity measurements were obtained from multiple areas of articular cartilage to identify an initial stage in osteoarthritis that is characterized in part by increased hydration of articular cartilage. At 6 weeks post-transection of the cranial cruciate ligament, an increase in signal intensity was detected in the articular cartilage of the weight-bearing portion of the lateral femoral condyle and the caudal portion of the medial tibial condyle with T1-weighted imaging. The increase in signal intensity may reflect increased proteoglycan synthesis by chondrocytes that also occurs early in the pathogenesis of osteoarthritis.

Low-field magnetic resonance imaging of early subchondral cyst-like lesions in induced cranial cruciate ligament deficient dogs

Six healthy adult male mongrel dogs underwent cranial cruciate ligament transection in the left stifle. Survey radiography of both stifles and low-field (0.064 T) MRI of the left stifle were performed preoperatively and at 2, 6, and 12 weeks postoperatively. Focal changes in signal intensity were seen with MRI in the subchondral bone of the medial tibial condyle at 2 and 6 weeks postoperatively. At 12 weeks postoperative, a cyst-like lesion was detected using MRI in the subchondral bone of the medial tibial condyle in 4 of 6 dogs and a less defined lesion at this site in the remaining 2 dogs. The cyst-like lesion was spherical in shape and showed typical characteristics of fluid with low signal intensity on T1-weighted images, high signal intensity on T2-weighted images and high signal intensity on inversion recovery images. The lesion was seen in the subchondral bone of the caudal medial and/or middle region of the tibial plateau slightly cranial to the insertion of the caudal cruciate ligament. No subchondral cysts were seen in the tibia on radiographs. Histopathologically, the tibia was characterized by a loose myxomatous phase of early subchondral cyst formation.

Low-field magnetic resonance imaging of the canine stifle joint: normal anatomy

Low-field magnetic resonance imaging (MRI) was performed on the stifle joints of four normal adult mongrel dogs using a 0.064 Tesla scanner. Markers were placed on each stifle joint to serve as reference points for comparing gross sections with the images. A T1-weighted sequence was used to image one stifle joint on each dog in the sagittal plane and the other stifle joint in the dorsal plane. The dogs were euthanized immediately following MRI and the stifle joints frozen intact. Each stifle joint was then embedded in paraffin, again frozen, and sectioned using the markers as reference points. On T1-weighted images, synovial fluid had low signal intensity (dark) compared to the infrapatellar fat pad which had a high signal intensity (bright). Articular cartilage was visualized as an intermediate bright signal and was separated from trabecular bone by a dark line representing subchondral bone. Menisci, fibrous joint capsule, and ligamentous structures appeared dark. In the true sagittal plane, the entire caudal cruciate ligament was often seen within one image slice. The patella was visualized as an intermediate bright signal (trabecular bone) surrounded by a low intensity signal (cortical bone). The trochlea and the intercondylar notch were difficult areas to analyze due to signal volume averaging of the curved surface of these areas and the presence of several types of tissues.

Lighting programs for broilers that reduce leg problems without loss of performance or yield

This study tested the effects of light schedules on performance and yields of broiler chickens. In Experiment 1, light treatments during Days 1 to 49 of age were: 1) 23 h light (L):1 h dark (D); 2) 16L:8D;3) 16L: 3D:1L:4D; and 4) 16L:2D:1L:2D:1L:2D. In Experiment 2, Light Treatments 1 and 2 were the same as Treatments 1 and 4, respectively, in Experiment 1; 3) 23L:1D Days 1 to 7, 16L:8D Days 8 to 14, the light period was increased by 2 h/wk during Days 15 to 35, and 23L:1D Days 36 to 42; and 4) 23L:1D Days 1 to 7, 16L:8D Days 8 to 14, 16L:3D: 2L:3D Days 15 to 21, 16L:2D:4L:2D Days 22 to 28, 16L: 1D:6L:1D Days 29 to 35, and 23L:1D thereafter. In Experiment 1, BW was greater in Treatment 4 than Treatment 2 at 22 (708 vs 642 g) and 49 d (2,948 vs 2,797 g), percentage leg problems was lower in Treatments 2 to 4 (9, 10 and 6%, respectively) than in Treatment 1 (20%), and percentage Grade A was greater in Treatment 4 than Treatment 2 (60 vs 46%) at 49 d. In Experiment 2, BW was greater in Treatment 1 (692 g) than Treatments 3 (617 g) and 4 (620 g) at 21 d, and the incidence of tibial dyschondroplasia was lower in Treatment 2 (3.1%) than Treatment 3 (15.3%) at 42 d. There were no differences for mortality among treatments in either experiment.

Nonlinear dynamics stability measurements of locomotion in healthy greyhounds

OBJECTIVE

To characterize normal locomotion of dogs, using nonlinear dynamic stability measurements to analyze two-dimensional kinematic data.

ANIMALS

5 healthy, orthopedically sound Greyhounds.

PROCEDURE

Data were studied by sequentially constructing phase plane portraits from the angular velocity and displacement data; creating first-return (Poincaré) maps from periodically sampled data; and evaluating the dynamic stability of the gait, using Floquet multipliers calculated from the assembled data. Retroreflective markers were placed on the left craniodorsal aspect of the iliac spine, greater trochanter, lateral epicondyle of the femur, lateral malleolus, and fifth metatarsophalangeal joint. Each dog was repeatedly led at a trot along a 10-m runway. Data were collected, using a video-based, two-dimensional motion measurement and analysis system. Dogs were considered a nonlinear system and were represented by the joint angular displacements and velocities. Phase plane portraits and first-return maps were constructed to analyze the smoothed data. The Floquet theory was then used to investigate the local stability of critical points of the discrete map.

RESULTS

The femorotibial joint had the highest angular velocity, ranging from -2.5 to 4.9 radians/s. Tarsal joint velocity ranged from -2.7 to 3.2 radians/s, and the coxofemoral angle had the lowest range of -2.2 to 2.2 radians/s. The points on the first-return maps converged to the 45 degrees diagonal line and were clustered together. The largest Floquet multiplier averaged 0.452, which characterized the stability of this population and will be used to draw a comparison between this and future work.

CONCLUSIONS

Nonlinear dynamics can be effectively used to analyze two-dimensional kinematic data from animal models to quantify the dynamic stability of animal locomotion through precise mathematical measurements. The method is general and can be applied to normal or abnormal gaits.

CLINICAL RELEVANCE

Point mapping and quantitative measurement of joint movement have several advantages associated with the application to animal and human locomotion. The clinician can visually distinguish the normal gait pattern from abnormal patterns to assist in the diagnosis of musculoskeletal abnormalities (diseases).

Immunolocalization of stromelysin, tumor necrosis factor (TNF) alpha, and TNF receptors in atrophied canine articular cartilage treated with hyaluronic acid and transforming growth factor beta

OBJECTIVE

To evaluate the ability of hyaluronic acid (HA), with and without transforming growth factor beta (1GF-beta), to stabilize the catabolic processes associated with atrophy of articular cartilage.

ANIMALS

20 adult, skeletally normal, hound-type dogs.

PROCEDURE

Dogs (20 to 30 kg) were randomly assigned to 1 of 5 groups. One group served as untreated controls. Bivalve casts were placed on the left hind limbs of the remaining 16 dogs to limit weightbearing and motion of the limb for 92 days. One group served as the cast control. Beginning on day 56, 3 groups received aseptic intra-articular injections in the left stifles of either 5 mg of HA or 5 mg of HA containing either 20 or 50 micrograms of TGF-beta. Intraarticular injections were repeated at 4-day intervals until the end of the study. Or day 92, stifles were harvested at necroscropy. Medial femoral condyle were histologically processed, and the articular cartilage was stained for the presence of proteoglycans, stromelysin, tumor necrosis facto (TNF) alpha, and TNF receptors (p55 and p75).

RESULTS

Decreased metachromasia was evident in the cartilage matrix of all cast groups, with the smallest decrease in the HA-treated group. Stromelysin was immunolocalized in articular cartilage of the cast (left) limbs of cast control and both HA/TGF-beta-treated groups. TNF-alpha was localized in articular cartilage of all cast (left) and right limbs, except those of the HA-treated group. Receptors for TNF were observed in both limbs of untreated control and cast control groups and cast limbs of HA/TGF-3-treated groups. The receptors were not localized in the right limbs of the HA with or without TGF-beta-treated groups. TGF-beta did not decrease stromelysin or TNF-alpha or receptors at the doses used.

CONCLUSIONS

HA may mediate a chondrostabilizing influence on articular cartilage by down-regulating TNF-alpha importantly. HA appeared to exert its inhibitory influence on TNF-alpha, as well as stromelysin and TNF receptors, on a systemic basis.

CLINICAL RELEVANCE

Results provide insight into the mode of action of HA as a therapeutic agent for arthritis and its stabilizing influence on cartilage metabolism.

Immunohistochemical analysis of an equine model of synovitis-induced arthritis

OBJECTIVES

To use lipopolysaccharide (LPS) to create synovitis in the midcarpal joint of ponies, and to assess the morphologic, histochemical, and immunohistochemical effects of synovitis on articular cartilage of the third carpal bone.

ANIMALS

2- to 3-year-old ponies, 6 control (group 1) and 6 treated (group 2).

PROCEDURE

Synovitis was induced in 1 midcarpal joint of group-2 ponies by intra-articular injections of LPS (0.02 micrograms/kg of body weight), morphine (0.1 mg/kg), and saline solution (group 2a) and a morphine and saline solution alone in the contralateral midcarpal joint (group 2b). Articular cartilage sections and attached synovial membrane from the third carpal bones were examined by immunohistochemical distribution of interleukin 1 beta, tumor necrosis factor (TNF)-alpha, TNF receptors (P55, P75) and 3-B-3(-) epitopes, and by localization of proteoglycans (metachromatic staining). Proteoglycan extracts were assessed by metachromatic staining or western blotting and immunohistochemical staining, using anti-3-B- antibodies.

RESULTS

Enhanced immunoreactivity for the cytokines and receptors was found in inflamed synovial membrane and noncalcified cartilage (group 2a more than 2b). Metachromasia of the noncalcified cartilage was greater in group-1 than in group-2a and group-2b specimens. In group 2a, chondrocyte hypertrophy and enhanced immunoreactivity for 3-B-3(-) epitope in areas of increased cytokine immunoreactivity suggested possible phenotypic change of the chondrocytes in response to synovitis. Immunohistochemical analysis by western blotting of proteoglycan extracts indicated strong 3-B-3(-) epitope immunolocalization in group-2a, weaker staining in group-2b, and barely detectable stain in group-1 specimens, which correlated with in situ immunolocalization.

CONCLUSIONS

Intra-articular administration of LPS may be used to induce a synovial environment conductive to increased immunoreactivity of interleukin 1 beta, TNF-alpha, and its receptors in equine synovial membrane and articular cartilage. These cytokines may be involved in the early phenotypic change of chondrocytes that is believed to occur in osteoarthritis and is characterized in this study by enhanced 3-B-3(-) epitope immunoreactivity and chondrocyte hypertrophy.

Morphology of the musculus articularis genus in dog with description of ectopic muscle spindles

The gross morphology of the musculus articularis genus and the location of muscle spindles at its point of insertion were studied in 18 adult dogs. The m. articularis genus was usually small and bipartite. From its originate on the cranial surface of the distal femur, it passed distally to terminate at the femoropatellar-joint capsule surface and extend into the synovial membrane. Although the m. articularis genus was usually composed of two parts, only a medial part was present in some dogs and was entirely absent in one specimen. Innervation to the m. articularis genus was provided by a branch of the femoral nerve. Muscle spindles were abundant in the termination of the muscle. spindles were abundant in the termination of the muscle. Frequently, the spindles were not in contact with muscle fibers (dissociated). Muscle spindles were located in close proximity to the surface of the synovial membrane. Morphological adaptations of the m. articularis genus support its potential function as a monitor of joint movement rather than an extensor of the stifle joint.

A comparison of laparoscopic and belt-loop gastropexy in dogs

A simplified technique for laparoscopic gastropexy (group 1) was compared to belt-loop gastropexy (group 2) in eight adult male dogs randomly divided into two groups of four dogs each. Our hypothesis was that a satisfactory laparoscopic gastropexy would approximate the strength and operative time required for belt-loop gastropexy. Operative time, surgical complications, postoperative morbidity, gross and histological appearance, radiographic microvascularization, and maximal tensile strength were measured and compared between the two groups. All dogs recovered from surgery. No morbidity was associated with either procedure. The mean (+/- SD) duration of surgery was 69.75 +/- 7.23 minutes for group 1 and 58.75 +/- 7.63 minutes for group 2. Fifty days after surgery, the microvascular appearance of the gastropexy site was similar for both groups. Blood vessels were observed within each seromuscular flap but vascular ingrowth to the abdominal musculature was observed in only two dogs, one from each group. The maximum tensile strength at 50 days was 76.55 +/- 22.78 for group 1 and 109.21 +/- 22.29 N for group 2. Differences between surgical duration and maximum tensile strength were not statistically significant (P > .05). Histologically, all gastropexies consisted of an adhesion composed of dense fibrous connective tissue. The results of this study indicate that laparoscopic gastropexy provides a minimally invasive alternative to open abdominal prophylactic gastropexy in dogs.

Effect of locally injected medications on healing of pad wounds in dogs

OBJECTIVE

To ascertain the effects of locally injected immunostimulant and tripeptide-copper complex (TCC) on improving healing of pad wounds.

DESIGN

Wounds in pads of large dogs were injected with either medication or physiologic saline solution (controls). Healing was evaluated.

ANIMALS

12 mature English Pointers.

PROCEDURE

Full-thickness 6 x 8-mm wounds in metatarsal and third and fourth digital pads were injected with immunostimulant or TCC at 0, 3, and 6 days after wounding. Wounds on control dogs were injected with physiologic saline solution. Using planimetric measurements at 0, 3, 6, 14, and 21 days, rates of healing were evaluated. Biopsy of the digital pad wounds at 3, 6, and 14 days was used to evaluate collagen content by hydroxyproline analysis. Biopsy specimens were also evaluated for type-I and type-III collagen, using Sirius red differential staining.

RESULTS

Effect on healing rate and hydroxyproline content was best during the first week for immunostimulant. Immunostimulant- and TCC-injected wounds had more type-I collagen than did controls at 6 days; TCC-injected wounds had the most type-I collagen. At 14 days, the amount of type-I collagen in TCC-injected wounds was significantly greater than that in other wounds.

CONCLUSIONS

Tested medications had positive effects on healing of pad wounds.

CLINICAL RELEVANCE

Intralesional injection of medications helps ensure their presence for enhancement of wound healing. The benefit could be lost with topical use in a bandage if the bandage is lost or becomes wet.

Tumor necrosis factor-alpha (TNF-alpha) in canine osteoarthritis: Immunolocalization of TNF-alpha, stromelysin and TNF receptors in canine osteoarthritic cartilage

The presence and distribution of tumor necrosis factor-alpha (TNF-alpha), TNF receptors and stromelysin [matrix metalloproteinase 3 (MMP-3)] in articular cartilage were evaluated in an iatrogenically induced model of osteoarthritis (OA). Eleven adult male dogs were assigned randomly to a control group (N = 4) or an OA group (N = 7). Osteoarthritis was created by surgical transection of the cranial cruciate ligament of one stifle joint. Both femoral condyles were sampled 3 months post-surgery at necropsy and immunohistochemically analyzed for the presence of the aforementioned cytokines and receptors. Chondrocytes stained for TNF-alpha and TNF receptors in control articular cartilage, spanning an area encompassing most of the middle and deep zones. Positive matrical and chondrocytic staining for TNF-alpha, TNF receptors, and stromelysin was present in OA articular cartilage. Staining varied in intensity and distribution and was dependent of the severity of the lesion. Smooth muscle cells of arteries and arterioles (periarticular synovial membrane) were stained for only one (p55) of two TNF receptors; this staining was confined to control tissues. Results indicate that the differential expression of TNF-alpha and its receptors may be important in the normal maintenance of articular cartilage. The increased presence of TNF-alpha and its receptors in articular cartilage with mild osteoarthritic changes suggests a role in the development of early OA. Regulating TNF-alpha may be an important component in the treatment of OA.

Immunohistochemical study of a chondroitin-6-sulfate in growth plates of broiler chickens with high and low genetic predispositions to tibial dyschondroplasia

The distribution of a chondroitin-6-sulfate (C6S) epitope, which is a biochemical marker of chondrocyte hypertrophy, was studied in the growth plates of two lines of 3-week-old broiler chickens with low and high genetic predispositions to tibial dyschondroplasia (TD). Ultrathin sections of growth plates from both groups were subjected to immunolocalization with monoclonal antibody 3-B-3(-), the epitope of which is increased on proteoglycans made by hypertrophic chondrocytes. Bound antibody was localized with colloidal gold-labeled protein A for observation with an electron microscope. The 3-B-3(-) epitope was localized in pericellular and interterritorial matrix of growth plates of both lines. In the low-TD-incidence birds, the concentration of 3-B-3(-) bound to C6S progressively increased from the proliferative zone to the hypertrophic zone. However, in the high-TD-incidence line, the epitope expression remained at a low level in all zones. The increase of the 3-B-3(-) epitope produced by maturing growth-plate chondrocytes is indicative of changes in the glycosaminoglycan chains of proteoglycans that may be important in the process of matrical calcification. Thus, failure of chondrocytes of the high-TD-incidence line to produce this change in post-translational modification of their proteoglycans could be important in the pathological process.

Redistribution of vertical ground reaction force in dogs with experimentally induced chronic hindlimb lameness

When lameness occurs in a load-bearing limb, compensatory load adjustments are made in the other supporting limbs. The vertical component of the ground reaction force, as measured by force platform analysis, reflects these adjustments. This study describes the pattern of vertical ground reaction force redistribution during experimental, chronic hindlimb lameness in dogs. The peak and impulse of the vertical ground reaction force were measured and described in 13 dogs before, and at 2, 6, and 12 weeks after transection of the cranial cruciate ligament. These variables were compared among limbs. The vertical ground reaction force in the forelimbs did not change significantly during the course of the study. At 2, 6, and 12 weeks after surgery, means of peak vertical force in the limb that underwent surgery were 18.9%, 44.0%, and 61.3% respectively, of presurgical values. In the contralateral limb, corresponding values were 131.7%, 112.8% and 112.9% respectively. If one accepts the relationship of mechanical loading to musculoskeletal architecture and the now certain relationship between lameness and compensatory loading of other limbs, then the use of another limb of the same animal as a control is a potential study design flaw.

Ultrastructural changes of chondrocytes of growth plates of young broiler chickens predisposed to tibial dyschondroplasia

Growth plates from the proximal tibiotarsal bones of growing broiler chickens from lines exhibiting high and low incidences of tibial dyschondroplasia (TD) were compared for ultrastructural differences. Samples of growth plates were collected from five chickens of each line at 2, 7, 14, and 21 d of age. Each sample was prepared for ultrastructural evaluation after initial fixation in 2.5% glutaraldehyde and secondary fixation in 1% osmium tetroxide, each containing .7% ruthenium hexamine trichloride. No gross TD lesions were observed. The ultrastructure of growth plates of birds at 2, 7, and 14 d of age was similar between the groups. However, at 21 d of age, chondrocytes in the prehypertrophic zone of the high incidence group contained large lipid inclusions and vesiculated and disarranged stacks of rough endoplasmic reticulum with greatly dilated cisternae. Apoptotic and necrotic chondrocytes were present in the hypertrophic zone. Nuclei of apoptotic chondrocytes contained crescentic caps of condensed chromatin. The cytoplasm contained short segments of dilated granular endoplasmic reticulum, lipid droplets, and vacuoles. Necrotic chondrocytes appeared as amorphous masses with pyknotic and karyorrhectic nuclei. These changes were not observed in chondrocytes of the low TD incidence group and have not been previously reported in nonthickened growth plate cartilage.

The intercondylar fossa of the normal canine stifle an anatomic and radiographic study

The intercondylar fossa (ICF) in dogs consists of a cranial outlet, intercondylar shelf, caudal arch, caudal outlet, a medial wall, and a lateral wall. The normal cranial outlet is bell-shape and, in mixed-breed dogs (mean body weight 19.2 kg, N = 21), measured 5.8 mm cranially, 8.1 mm centrally, and 10.3 mm caudally. The ICF is oriented 12 degrees from the dorsal plane of the femoral diaphysis and obliqued 7 degrees, proximolateral to distomedial, in the sagittal plane. To adjust for dog size, a fossa width index (FWI) was calculated by dividing the cranial outlet width by the distance between epicondyles. The normal FWI as determined in this study was 0.18 cranially, 0.25 centrally, and 0.32 caudally. The fossa height index 0.31. Contact between the ICF and the cranial cruciate ligament began at about 115 degrees of extension. The contact area moved cranially in the intercondylar fossa as the stifle was extended. Evaluation of the ICF can be performed radiographically but positioning is critical.

The effect of intercondylar notchplasty on the normal canine stifle

This study evaluated the effect of notchplasty (enlargement of the intercondylar fossa) in stable and unstable canine stifles. Bilateral notchplasty and unilateral cranial cruciate ligament (CrCL) transection were performed in 6 dogs. Exercise, consisting of walking 1.5 miles three times a week, began 1 month after surgery and continued until euthanasia 6 months after surgery. Evaluation methods included orthopedic examination, serial radiographs, thin section radiography, histopathology, and gross pathology. Notchplasty in the stable stifle did not cause lameness beyond 3 weeks, joint instability, or degenerative joint disease. In the stable stifle, smooth resurfacing of the notchplasty site with fibrous and osseous tissue occurred. Stifles with notchplasty and CrCL transection exhibited persistent lameness, instability, and degenerative joint disease. In CrCL deficient stifles osteophytes formed within the notchplasty site, resulting in a rough surface. Our observations indicated significant refilling in notchplasties of both stable and unstable stifles (P < .05). However, the intercondylar fossa (ICF) width 6 months after notchplasty was significantly smaller in unstable stifles compared with stable stifles (P < .05) indicating that greater refilling of the notchplasties occurred in the unstable stifles. In clinical cases, notchplasty should be larger than the desired final result to accomodate the partial refilling that occurs even in stable stifles.

Lack of interactions between dietary lysine or strain cross and photoschedule for male broiler performance and carcass yield

The purpose of this study was to test interactions of dietary lysine or strain crosses provided increased lysine with photoschedule on broiler performance and carcass quality. In Experiment 1, treatments were factorially arranged as two lysine levels [control grower and finisher (NRC, 1984) or control grower and finisher plus .15% L-lysine HCl] and two photoschedules [23 h light (L):1 h dark (D) or 14L:10D]. All birds received a control starter feed and dietary treatments were initiated at 22 d of age. In Experiment 2, treatments were factorially arranged as two strain crosses [Peterson x Arbor Acres (PAA) or Ross x Ross (RR)] and two photoschedules (23L or 16L). All birds received standard starter and standard grower and finisher plus .15% L-lysine HCl. There were no lysine by photoschedule or strain cross by photoschedule interactions in this study. The high-lysine diet increased BW, improved feed efficiency, increased lean carcass weight and yield of breast meat, and decreased abdominal fat and yield of thighs. The PAA strain cross had better feed conversion, fewer Grade A carcasses, more back bruises and breast blisters, greater yield of wings and drumsticks, and less yield of breast meat than RR. The 23L had greater BW, better feed efficiency, fewer breast blisters, greater carcass weight (Experiment 1), more abdominal fat (Experiment 2), lower yield of wings (Experiment 1), drumsticks, and thighs, and greater yield of breast meat than the treatments with shorter photoschedules. Increased dietary lysine did not compensate for decreased breast meat yield associated with 14L (Experiment 1).

Ground reaction force profiles from force platform gait analyses of clinically normal mesomorphic dogs at the trot

Force platform analysis of gait provides ground reaction force information that can be used to study limbs with normal or abnormal function. When combined, the interrelated variables of ground reaction forces give a more thorough description of gait than when used individually. To describe the pattern of ground reaction forces in clinically normal, conditioned, mesomorphic dogs, we studied the data from platform gait analyses of 43 dogs. Mediolateral (Fx), craniocaudal (Fy), and vertical (Fz) forces were measured and recorded. Torque (Tz) around the vertical axis also was calculated. Mean stance times for forelimbs and hind limbs were 0.278 and 0.261 second, respectively. Among dogs, ground reaction forces were normalized and expressed as percentage of body weight (%bw). The vertical (Fz) peak, average force during stance phase, and force vs time impulses were 106.68, 60.82, and 17.2 %bw in forelimbs, and were 65.11, 35.3, and 9.33 %bw in hind limbs. The forelimb braking/propulsive (Fy) peaks were -16.74 and +6.73 %bw. In hind limbs, these peaks were -3.76 and +7.69 %bw. The usual mediolateral force (Fx) pattern found in forelimbs was laterally directed, with average peak magnitude of 6.69 %bw, whereas the hind limb patterns were variable.

Vertical ground reaction force distribution during experimentally induced acute synovitis in dogs

The pattern of vertical ground reaction force redistribution among limbs during episodes of acute synovitis of the stifle in 12 mixed-breed dogs was investigated as an adjunct to a blinded nonsteroidal anti-inflammatory drug efficacy study. Without regard to drug efficacy groupings, the redistribution of vertical forces before and during the acute synovitis episode was evaluated by analysis of gait, using a force platform. Acute synovitis was induced by intrasynovial injection of sodium urate crystals. Simultaneously, each dog was given 1 of 4 treatment regimens, including IV injection of sterile saline solution (as a negative control), phenylbutazone (as a positive control), or 1 of 2 proprietary nonsteroidal anti-inflammatory drugs. Postinjection analyses took place at 2, 4, 8, 12, 24, and 36 hours. The peak vertical force redistribution in the 3 untreated limbs of the dogs was described. The greatest redistribution was observed 4 hours after substance injection when the synovitis was clinically at maximum. Thereafter, there was steady improvement and the dogs had a clinically normal gait 24 hours after substance injection. During synovitis, peak vertical force increased in the contralateral hind limb. During the more severe synovitis episodes, force was decreased in both forelimbs. There was good correlation between severity of lameness and peak vertical force response in the contralateral hind limb. Results of the study indicate that the untreated limbs of the same animal should not be used as a control during acute lameness studies.

Effects of photoschedule and strain cross on broiler performance and carcass yield

The purpose of the present experiment was to examine possible interactions of strain cross and age with photoschedule for broiler performance and carcass yield. Day-old male broiler chicks from strain crosses of either Peterson x Arbor Acres (PA) or Ross x Arbor Acres (RA) were placed in light-controlled chambers (5.6 lx) with either 23 h light (L):1 h dark (D) from 1 to 56 days (Treatment E) or 6L:18D from 1 to 14 days and 1L:3D repeated from 15 to 56 days of age (Treatment BI). There were age by light treatment and age by strain cross interactions for BW; Treatment E had greater BW than Treatment BI from 7 to 42 days, and the PA cross BW was greater than the RA cross BW from 1 to 42 days of age. Cumulative feed efficiency was improved by Treatment BI compared with Treatment E up to 49 days. There were no differences among main effects for mortality, and the incidence of leg problems increased with age. Fillet and tender yields (per lean carcass weight) were higher for Treatment E than BI and opposite responses were seen for drumstick and thigh yields. The RA cross showed higher fillet and tender yields than the PA cross and the opposite relationship was found for drumstick and wing yields.

Live performance and carcass yield of broiler strain crosses provided either sixteen or twenty-three hours of light per day

The purpose of the present study was to compare a restricted (R) lighting program [16 h light (L):8 h dark (D)] with a standard extended (E) lighting schedule (23L:1D) for broilers. Experiment 1 was carried out during March and April (mean temperature of 23.3 C). Light treatments were 1) E; 2) R; 3) 16L:8D Days 1 to 21 and 23L:1D thereafter to 49 days (R3E); and 4) 16L:8D Days 1 to 14 and 23L:1D thereafter to 49 days (R2E). Treatments were factorially arranged with two strain crosses [Indian River x Arbor Acres (IA) and Peterson x Arbor Acres (PA)]. Experiment 2 was carried out during the summer (mean temperature of 27.0 C). Light Treatments E and R were factorially arranged with two strain crosses [Cobb x Arbor Acres (CA) and PA]. In Experiment 1, BW of Cross PA was greater than BW of Cross IA at 1, 14, 35, and 49 days of age. The percentage of birds with breast blisters was greater in Cross PA than IA. The incidence of broken clavicles was lower in Treatments R and R3E than in Treatments E or R2E. In Experiment 2, Treatment E had greater BW than R from 7 to 42 days of age, and BW of Cross CA was greater than that of PA from 1 to 48 days. Yield (percentage of lean carcass weight) of breast meat at 49 days of age was higher for Treatment E than R, and the percentage of birds with breast blisters was greater in Treatment R than E.(ABSTRACT TRUNCATED AT 250 WORDS)

Live performance and yields of broilers provided various lighting schedules

The purpose of the present study was to measure performance and carcass yield from broilers maintained on photoschedules that may influence incidence of leg disorders. Day-old male broilers were placed on litter floors of light-controlled chambers. Four chambers were randomly assigned to each of four light treatments: 1) 23 h light (L): 1 h dark (D) from 1 to 56 days of age (designated extended, E); 2) 1L:3D from 1 to 56 days (intermittent, I); 3) 6L:18D from 1 to 14 days and 1L:3D from 15 to 56 days (brief-I, BI); and 4) 6L:18D from 1 to 14 days and 23L:1D from 15 to 56 days (brief-E, BE). Mean (+/- SEM) light intensity was 5.4 +/- .26 lx for all light treatments. At 13, 21, and 42 days of age, Treatments BI and BE had lower BW than Treatment E. The percentage of birds with leg abnormalities among treatments was greater at 56 days than at 42 days. The BI birds had significantly fewer leg abnormalities than E birds. There was an age by treatment interaction for the frequency of tibial dyschondroplasia (TD), with BI showing better recovery from TD at 56 days than other treatments. At 42 days of age, split breast yield (percentage of BW) was greater in E than I, and breast yield (percentage of lean carcass) was greater in E and BI compared with I. At 56 days of age, yield (percentage of BW) of tenders was lower in I and BI compared with E and BE.(ABSTRACT TRUNCATED AT 250 WORDS)

Cartilage canals and lesions typical of osteochondrosis in growth cartilages from the distal part of the humerus of newborn pigs

Vessels in cartilage canals supplying the articular-epiphyseal cartilage complex and growth plate of the distal part of the humerus of pigs between on day and 15 weeks old were examined in perfused and cleared specimens, and histochemical preparations. An extensive capillary network surrounded the arterioles and venules and probably maintained the circulation of blood as the ends of the cartilage canals underwent involution. Pits and grooves were in predilection sites for osteochondrosis and osteoarthrosis and were typical of early lesions of these conditions. Some ghosts that were observed mesoscopically were chondrified cartilage canals or remnants of cartilage canals in histological sections, and were considered to be the result of a normal process. However, abnormal involution may predispose to chrondrolysis, and the presence of involuting transverse cartilage canals at predilection sites implicated damaged canals in the aetiopathogenesis of osteochondrosis and osteroarthrosis in some pigs. Cleared specimens provided the most useful demonstration of the form and distribution of cartilage canals, ghosts, and pits or grooves. The association of cartilage canals with areas of chondrolysis, and the distribution of ghosts in the predilection sites for lesions, warrant further investigation of blood vessels within cartilage canals.

The development of centres of ossification of bones forming elbow joints in young swine

Epiphyseal centres of ossification in the bones forming the elbow joints of pigs between one day and 15 weeks of age were examined radiographically, macroscopically, mesoscopically and microscopically. Thoracic limbs from 39 pigs were perfused with India ink or silicone rubber injection compound and the bones were dissected free of soft tissues. The humerus, ulna and radius were fixed in formalin or ethyl alcohol and then cleared by the modified Spalteholz technique. Bones were radiographed, examined grossly, and then cut into slabs for mesoscopical evaluation. Foci considered to be calcifying within cartilaginous anlage were selected for microscopical examination. It was concluded that the epiphyseal centre of ossification develops at different times in different sites in the bones forming the elbow joint. Centres of ossification are initiated when foci of chondrocytes adjacent to one side of a cartilage canal undergo hypertrophy and the inter-territorial matrix becomes calcified. Osteogenesis then proceeds in the calcified focus, presumably with osteoprogenitor cells that originate within the cartilage canals. Subsequently, each epiphyseal centre of ossification enlarges by one of two methods. Firstly, the layer of cartilage adjacent to the centre undergoes endochondral ossification, thus allowing for the circumferential growth of the epiphyseal centre of ossification. Secondly, foci of calcification develop adjacent to the ends of cartilage canals near the epiphyseal centre of ossification and eventually the focus of calcification coalesces with the developing epiphyseal centre of ossification, thus establishing a new ossification front. Endochondral ossification continues at the periphery of the mass of bone. Mesoscopical examination is more useful than radiographical evaluation for identifying small foci of calcification which precede epiphyseal centres of ossification.

The vascular supply of the chondro-epiphyses of the elbow joint in young swine

The vasculature of the elbow joint was examined in 39 pigs between one day and 15 weeks of age. Each pig was anaesthetised, exsanguinated and the thoracic limbs were perfused with India ink or a silicone rubber injection compound. The humerus, ulna and radius were dissected free, examined, fixed in formalin or ethyl alcohol, cleared by the modified Spalteholz technique and examined mesoscopically. Features of interest were photographed and then a limb from two pigs in each age group was cut into slabs and examined mesoscopically. The vascular supply of the distal part of the humerus was complex. It was supplied by vessels on both the cranial and caudal aspects and locally each aspect had a dual blood supply. Vessels anastomosed and on the cranial aspect formed a vascular ring. The proximal part of the ulna was supplied by vessels that were on its medial and lateral surfaces. The vessel on the lateral surface continued distally and supplied the lateral aspect of the proximal part of the radius. The proximal part of the radius was also supplied by arteries that were on the cranial and medial surfaces. Blood vessels provided branches to numerous cartilage canals of the articular-epiphyseal cartilage complexes, epiphyseal centres of ossification, and growth plates. The patterns of blood vessels in cartilage canals which were in sagittal or transverse planes were best exemplified by those in the distal part of the humerus. Perforating cartilage canals emerged from the epiphyseal centres of ossification. The pattern of cartilage canals was consistent in a general configuration, but individual variation did occur. Although cartilage canals were abundant in the youngest pigs, with increasing age the distribution of cartilage canals changed and the numbers of cartilage canals decreased.

The effects of beveling the margins of articular cartilage defects in immature dogs

Eight 4 month old crossbred puppies underwent surgery simulating treatment of osteochondritis dissecans. Both humeral heads were exposed by a caudal approach to the shoulder joint. In one, an 8 mm circular, full-thickness cartilage defect was created so that the remnant cartilage margin was perpendicular to the joint surface. In the other, a similar 8 mm defect was created with the chondral margins beveled at approximately 45 degrees. There was no clinical lameness in any of the dogs. At necropsy after 16 weeks, the cartilage defects with beveled edges were significantly larger (11.0 +/- 0.6 mm SD) than those with perpendicular edges (8.0 +/- 0.1 mm SD), because of the beveling (p = 0.0039). Fibrocartilage was present but did not always completely fill the defects. Articular surfaces of the glenoid cavities suffered erosion and fibrillation more frequently opposite beveled defects than opposite defects with vertical walls (p = 0.0312). This was presumably due to the larger apposing defect. It was concluded that the cartilage margins surrounding a chondral defect should not be beveled.

Observations of fracture of the anconeal process of the ulna of swine

Fractures of the anconeal process of 5 pigs ranging in age from 4 to 8 months were studied radiographically and histologically. Clinically, animals with a fracture of the anconeal process had a "tight," restricted gait. In pigs at 4.5 months of age, a radiolucent line through the base of the anconeal process was composed of fibrocartilage, fibrous connective tissue, and hyaline cartilage. Subperiosteal proliferation of woven bone was located along the cranial surface of the olecranon, adjacent to the base of the anconeal process. In older animals, the radiolucent line through the anconeal process contained variable amounts of fibrous connective tissue and fibrocartilage. The proliferation of subperiosteal bone at the base of the anconeal process formed a "buttress callus" which retained a radiolucent area between the callus and the proximal surface of the anconeal process. The latter region of radiolucency was continuous with the transversely oriented line that traversed the base of the anconeal process.

Lipids of normal and osteochondritic cartilage of the immature canine humeral head

Specimens of cartilage removed from the shoulder joint of dogs with osteochondritis dissecans were compared with the articular-epiphyseal cartilage from the same location of healthy dogs. The pathologic cartilage lost the lamination pattern of articular-epiphyseal cartilage from healthy dogs. Chondrocytes of healthy and pathologic cartilage contained lipid inclusions. However, in pathologic samples, the lipid inclusions were more prominent, particularly in the superficial region of the presumptive articular cartilage. Lipids in the interterritorial matrix of the pathologic cartilage were observed. The pathologic cartilage contained large groups of chondrocytes and areas of mineralization of variable magnitude. Although lipid inclusions were found in the chondrocytes of cartilage of healthy dogs, the increase in magnitude of lipids in the cartilage from dogs with osteochondritis dissecans was considered to result from a metabolic response of the chondrocyte to an altered microenvironment. The loss of sudanophilic lipids in areas of chondrolysis may be used to explain the retardation of osteogenesis of chondrolytic cartilage.

Chondrolysis associated with cartilage canals of the epiphyseal cartilage of the distal humerus of growing pigs

The articular-epiphyseal (A-E) cartilage of the distal humeri of 7 pigs weighing 13.1 to 18.2 kg and of 3 pigs weighing 36.4 to 40.9 kg was studied. Frozen samples of A-E cartilage were stained for the presence of reduced nicotinamide adenine dinucleotide dehydrogenase, lactate dehydrogenase, isocitrate dehydrogenase, and uridine diphosphate galactose-4-epimerase. Additional frozen sections and paraffin-processed sections were stained using the Alcian blue-critical electrolyte concentration method, safranin O-fast green, and hematoxylin and eosin. An area of grossly visible, opaque A-E cartilage of the medial condyle corresponded to regions of chondrolysis of the epiphyseal cartilage. The chondrolytic regions contained chondrocytes that did not stain for enzymes, had reduced staining for proteoglycans in the matrix, and were located at the site where the A-E cartilage increased in thickness. Cartilage canals were associated with the chondrolytic areas. Cartilage canals in both groups of pigs were commonly in various stages of chondrification, some of which were associated with degenerative cartilage. The regions of chondrolysis may indicate sites of biomechanical weakness in the A-E cartilage during the transformation of the epiphyseal cartilage into bone.

En bloc staining of articular cartilage and bone

Blocks of canine and porcine articular cartilage were stained en bloc with Weigert's iron hematoxylin or Harris' hematoxylin with or without eosin Y counterstaining and cleared in methyl salicylate. The morphology and three-dimensional relationships of chondrocytes were best demonstrated with Weigert's iron hematoxylin. The morphology of the cartilage and chondrocytes was superior to that in sections of routine hematoxylin and eosin stained, paraffin processed samples. The three-dimensional localization of intracellular lipids in individual and clones of chondrocytes was observed when cartilage samples were stained with oil red O and mounted directly in a water-based medium. Blocks of decalcified bone were stained en bloc with Weigert's iron hematoxylin and cleared with methyl salicylate. The three-dimensional orientation of osteocytes around osteonal canals, in circumferential lamellae, and in interstitial lamellae was demonstrated. The morphology of "cutting cones" in cortical bone also was observed.

Observations on the postnatal morphogenesis of the porcine humeral condyle and the pathogenesis of osteochondrosis

The condyles of the distal humeri of 75 pigs ranging in age from 1 day to 9 months were studied by gross observation and radiography. Twenty-eight pigs were reared on pasture, necropsied, and were studied histologically. The portion of the secondary center of ossification of the distal humeral epiphysis located in the lateral condyle of neonatal pigs was larger than that observed in the medial condyle and assumed the contour of the articular surface at an earlier age. Thus, the articular-epiphyseal cartilage of the medial condyle had an inherent propensity to be thicker than that of the lateral condyle and might be predisposed to the influence of deleterious biomechanical insult. Projections of cartilage containing degenerating chondrocytes from the epiphyseal cartilage into the subadjacent trabecular bone may have been early lesions of osteochondrosis in pigs less than or equal to 3 months of age. Osteochondral and articular fractures of the medial condyles and intercondylar cristae of the distal humeri of 6- to 9-month-old pigs were observed. Seemingly, fractures resulted from shearing forces within the humeral articular surfaces at the junction of the articular-epiphyseal cartilage continuum and the subchondral epiphyseal bone with subsequent separation of the tissues at the osteochondral interface. Such shearing forces could result from a torque and/or laterally to medially directed forces of unusually great magnitude generated by movement of the proximal radius against the distal humerus.(ABSTRACT TRUNCATED AT 250 WORDS)

Experimental copper deficiency in laboratory mice

Copper deficiency was produced in weanling C57BL/6J and Hap:(ICR) mice that were fed a milk-sucrose based diet supplemented with appropriate vitamins, minerals, and amino acids. Growth retardation, decreased hematocrit, lethargy, dyspnea, achromotrichia, and high mortality (in ICR mice) were apparent in copper-deficient mice. Cardiac enlargement, hemopericardium, hemothorax, and pleural effusion were observed at necropsy. Thrombosis of the atria, myocardial degeneration and necrosis, and sites of myocardial rupture were observed at histopathologic examination.

Effects of exercise on the histochemical changes of articular chondrocytes in adult dogs

Effects of exercise regimens on the enzyme histochemical changes of articular chondrocytes of the humeral heads in adult shepherd-type dogs were studied. One group of 4 dogs was exercised by walking on a flat surface 5 days a week for 6 months. A 2nd group of 4 dogs was exercised under the same conditions, except that the dogs were forced to walk over platforms placed in their path. Three control dogs were exercised ad libitum in their housing area. In all dogs, the reactivity of lactic acid dehydrogenase was quite strong nicotinamide dinucleotide dehydrogenase was moderate, and glucose-6-phosphatase was week. Succinic acid dehydrogenase uridine diphosphate (UDP)-galactose-4-epimerase, and UDP-N-acetylglucosamine-4-epimerase were of weakly moderate staining reactivity. Consistent regional or laminar variability was not found among the chondrocytic populations of the exercised and control groups for the reactivity of the enzymes studied. However, regional and/or laminar variabilities in individuals of the experimental groups were identified. The weak reactivity of glucose-6-phosphatase as seemingly contradictory to the presence of intracellular lipids of adult articular chondrocytes. Lipid synthesis was suggested as a mechanism to store excessive quantities of hydrogen ions in an innocuous form, rather than in the potentially deleterious by-product of anaerobic glycolysis, lactic acid.

Communicating cartilage canals of the physis of the distal part of the ulna of growing swine and their potential role in healing of metaphyseal dysplasia of osteochondrosis

The distal parts of ulnae of 22 pigs ranging in age from 1 day to 6 months were studied histologically. Communicating cartilage canals passing from the epiphyseal vasculature through the physis and anastomosing with the metaphyseal vasculature were identified in neonatal pigs. In older pigs, the communicating cartilage canals had become smaller, as evidence by the presence of only capillaries. Eosinophilic matrical strekas and patches containing scattered elongated nuclei and centrally located accumulations of erythrocytes within the physis became more numerous in groups of old pigs. These streaks were considered to be compressed, nonpathologic extensions of the communicating physeal cartilage canals. In abnormally thick physeal cartilage of dysplastic 3-month-old-pigs, ossification was observed around hypertrophied communicating cartilage canals in the central portion of the lesion. Presumably, with reestablishment of endochondral ossification, the physis could return to its normal thickness and laminar pattern.

Postnatal morphogenesis of the anconeal process of the ulna of swine

The proximal ulnae of 79 swine ranging in age from 1 day to 2 years were radiographed and those of 46 of the swine were studied histologically. The anconeal process was a hyaline cartilaginous model at birth but ossified by 6 months of age. Endochondral ossification began at the base of the anconeal process and progressed in a pyramidal manner toward its apex. Secondary center of ossification was not observed in porcine anconeal processes examined. A lesion in the anconeal process of a 2-year-old animal was interpreted as a fracture of the anconeal process, and not a fracture of an anconeal physis. Implications of the development of the anconeal process as related to osteochondrosis in swine were discussed.