Bicarotid Trunk in the Domestic Cat.

The origin of the pair of common carotid arteries in the cat is inadequately described, and there are conflicting accounts in English veterinary anatomy textbooks published in the USA. We found one-quarter of 40 adult domestic cats dissected had a bicarotid trunk (5 female, 5 male). When present, the bicarotid trunk arose from the brachiocephalic trunk approximately midway between the expected origins of the more frequently independently arising left and right common carotid arteries, and on average, it was 5.6 mm in length. Our findings make the incidence, topographical and measurement information available so that students and veterinarians can be aware of this not insignificant variation in branching of the major arteries, forming a bicarotid trunk, in the cranial mediastinum of domestic cats.

In vitro effects of epidermal growth factor or insulin-like growth factor on tenoblast migration on absorbable suture material.

OBJECTIVE: To determine the effects of epidermal growth factor (EGF) or insulin-like growth factor (IGF) on tenoblast migration on absorbable suture material using an in vitro model. STUDY DESIGN: An in vitro evaluation of tenoblast migration. ANIMAL OR SAMPLE POPULATION: Segments of the long digital flexor tendon were obtained from Cobb chickens (9-11 weeks old) immediately after the birds were euthanatized. METHODS: Tissue culture explants of tendons containing absorbable suture material were treated with either EGF or IGF. Tenoblast migration was assessed daily using an inverted microscope equipped with bright field and phase optics. Tenoblast migration was assessed according to the following criteria: time of first cell appearance, percent of explant interfaces producing cells, migration distance, and terminal migration index at 120 and 168 hours. RESULTS: EGF had a stimulatory effect on tenoblast migration for cells originating from the endotenon interfaces. No significant effect was noted on migration distance for cells originating from epitenon interfaces. A stimulatory effect on the percentage of interfaces producing cells and a significant decrease in time of first cell appearance were also observed after EGF treatment. IGF-stimulated cell migration distance for epitenon interfaces but this stimulatory effect did not occur at a higher concentration. IGF was inhibitory to percent of epitenon and endotenon interfaces producing cells but decreased time of first cell appearance at low concentration. CONCLUSIONS: Using an in vitro model, EGF had a stimulatory effect on tenoblast migration. IGF was stimulatory at low concentration levels but inhibitory at a higher concentration. Increased migration distance was observed for endotenon interfaces after EGF treatment and for epitenon interfaces after IGF treatment. CLINICAL RELEVANCE: EGF or IGF might enhance tendon repair if they could be delivered to the repair site. Incorporation of EGF or IGF into suture material would allow slow release and prolonged exposure of migrating tenoblasts to growth factors.

Biochemical and morphological alterations in xylazine-induced pulmonary edema.

Sprague-Dawley rats were given 42 mg/kg xylazine intramuscularly, and lungs were lavaged with phosphate-buffered saline 3, 6, and 12 hr later. Total protein, lactate dehydrogenase (LDH), xanthine oxidase (XO), tumor necrosis factor (TNF), and interleukin 1 (IL-1) were measured in bronchoalveolar lavage fluid (BALF). Protein concentration, LDH, XO, and TNF levels were increased (p < 0.05) in the BALF from xylazine-treated rats as compared to controls. IL-1 level was unchanged at 3 and 6 hr and was reduced (p < 0.05) at 12 hr. Another group of rats was given 42 mg/kg xylazine intramuscularly, and lungs were fixed 0.5 and 12 hr later. Histologically, severe pulmonary edema (PE) involving the alveoli and perivascular stroma was observed. Fibrin, increased numbers of eosinophils, and macrophages with foamy cytoplasm were present in the alveoli of all treated animals. Ultrastructurally, endothelial damage, characterized by thinning, detachment from basement membranes, or bleb formation, was observed. The lesions were similar in both xylazine groups, differing mainly in severity with the 12-hr group having more severe lesions than the 0.5-hr group. To determine whether endothelial injury is caused by direct toxicity of xylazine, bovine pulmonary artery endothelial cells (BPAECs) were incubated with xylazine (0.3, 3, and 30 micrograms) for 0.5 or 3 hr. Xylazine did not have any effects on BPAECs, as indicated by phase-contrast microscopy and dye-exclusion viability assay. These results indicate that xylazine-induced PE is due to increased permeability resulting from endothelial injury, which is not caused by direct effect of xylazine on pulmonary endothelium. While oxygen radicals and TNF are possibly involved, IL-1 does not appear to play a role in xylazine-induced PE.

A comparison of nylon, polybutester, and polyglyconate suture materials for long digital flexor tenorrhaphy in chickens.

Digital flexor tenorrhaphies were performed in 32 8-week-old chickens with polyglyconate, polybutester, or nylon. There was no difference in maximum loads to failure at weeks 4 or 8. Polyglyconate and polybutester tenorrhaphies were significantly stronger at week 8 than all tenorrhaphies at week 4. Nylon tenorrhaphies at week 8 were not significantly stronger than any tenorrhaphy at week 4. The tenorrhaphies consistently had immature scars at week 4 and more mature scars at week 8. Scar maturity was not appreciably different between any of the suture materials at week 4 or week 8. There was no apparent difference in tissue reactivity to any of the suture materials at weeks 4 or 8.

Strength characteristics and failure modes of locking-loop and three-loop pulley suture patterns in equine tendons.

Size 3-0 polydioxanone was used as a single strand, single braid (3 strands), or double braid (6 strands) to create six suture material-pattern combinations for equine tenorrhaphy: single-strand locking loop, single-braid locking loop, double-braid locking loop, single-strand three-loop pulley, single-braid three-loop pulley, and double-braid three-loop pulley. Maximum load to failure for the single-strand locking loop (46.1 +/- 2.9 newtons [N]) was less than for all other sutures (range, 103-155 N). The load required to form a 2 mm gap between tendon ends was greater for the single-braid three-loop pulley (66.7 +/- 6.9 N) and double-braid three-loop pulley (85.4 +/- 17.7 N) than any other sutures. The load required to produce a 10 mm gap was least for the single-strand locking loop (34.3 +/- 3.9 N) and greatest for the double-braid three-loop pulley (131.5 +/- 27.5 N). Gap between tendon ends at maximum load was greater for the single-braid (18.1 +/- 0.9 mm) and double-braid (19.2 +/- 2.2 mm) locking loops than for any other sutures. Suture material broke in 53% of the locking-loop tests but in only 17% of the three-loop pulley tests. Tendon matrix disruption accounted for 43% of the locking-loop failures and 77% of the three-loop pulley failures. The three-loop pulley pattern provided more support, less tendon distraction, and less tendon matrix constriction and distortion than the locking-loop pattern.(ABSTRACT TRUNCATED AT 250 WORDS)

Strength characteristics and failure modes of suture patterns in severed goat tendons.

The load-to-gap formation, maximum load, gap present at maximum load, and failure mode were compared among four suture patterns: Bunnell-Mayer, modified Kessler, Mason-Allen, and simple interrupted. Sixty-four goat tendons were sutured with 2-0 monofilament polypropylene in one of the patterns and distracted at 92 cm/min with an electrohydraulic materials testing system. All tests were filmed at 40 frames/sec with an intermittent pin registered camera. The load-to-gap formation was not significantly different among the Bunnell (13.3 +/- 1.5 newtons [N]), Kessler (12.8 +/- 1.3 N), and simple interrupted (11.7 +/- 1.7 N) patterns. The Mason-Allen pattern was significantly different )8.2 +/- 0.5 N). The Bunnell-Mayer had the highest mean maximum load to failure (43.0 +/- 1.6 N) followed by the modified Kessler (34.1 +/- 1.9 N). There was no difference between the Mason-Allen (22.9 +/- 1.4 N) and simple interrupted (21.2 +/- 1.4 N). All of the patterns permitted at least a 1 cm gap to form when the maximum load was applied. The Bunnell pattern caused severe constriction of the tendon and failed by suture material disruption. The modified Kessler caused some focal constriction, but the suture material pulled out before breaking and sliced the tendon in the process. The Mason-Allen and the simple interrupted patterns sliced the tendon as the suture pulled out of the tendon.

A comparison of steady state and transient thermography techniques using a healing tendon model.

Steady state and transient thermal techniques were used to define the thermal signatures of surgically sectioned and sham-operated common calcanean tendons in four dogs. All limbs were imaged from the lateral side using an Inframetrics 525 system at - 1, 2, 4, 6, and 8 weeks after surgery. Individual video frames were used to compute absolute surface temperatures and rewarm curves for five predetermined 1 cm2 skin areas. Angiography was performed at each observation period to correlate changes in vascular morphology and thermal data. Thermal signatures and angiograms were similar in all animals before surgery. At 2 and 4 weeks after surgery, the absolute surface temperatures of the entire lateral crus area were elevated in three of four animals. During weeks 6 and 8, the surface temperatures, rewarm curves, and angiograms returned to presurgical values for the controls. Skin areas over the repaired tendons remained warmer and were shown to correlate with vascular proliferation by transient but not steady state techniques. Steady state and transient thermal imaging techniques can be used to detect vascular changes in the area around a healing tendon. However, our data indicate that transient thermal techniques are more suitable than steady state methods for localizing vascular disturbances in tissues. Thermographic imaging techniques may become a reliable noninvasive method to monitor wound healing processes if starting temperatures, cool down techniques, and time intervals for data collection are fully evaluated in future studies using transient thermal imaging protocols.

Morphologic comparison of healing patterns in ethylene oxide-sterilized cortical allografts and untreated cortical autografts in the dog.

Full-thickness canine cortical allografts were harvested cleanly, sterilized with ethylene oxide, and stored at 22 degrees C. The sterilized allografts were incorporated into segmental, femoral fracture repairs and evaluated for 6 months. Allografts were compared with untreated cortical autografts, which also were incorporated into segmental, femoral-fracture repairs for 6 months. Sequential fluorochrome labeling at 8, 11, 21, and 24 weeks after surgery made it possible to evaluate retrospectively the time of new bone formation. Morphometric evaluations were made of the numbers of labeled haversian systems, the percentage of labeled bone, and the porosity of the bone. The cortical allografts had bone formation in the proximal and distal portions of the graft, with the greatest activity at 5 to 6 months after surgery. Activity in the center of the allograft was minimal. Cortical autografts had bone formation throughout the graft, with the greatest number of haversian systems labeled at 3 months after surgery. We concluded that cortical allografts heal and remodel more slowly and in a different sequence of events than do cortical autografts.

Evaluation of experimental transection and partial excision of the caudal cruciate ligament in dogs.

The caudal cruciate ligament (CaCL) of one stifle joint in seven dogs was transected and a 2 to 4 mm section was removed. Six months after surgery, none of the dogs were lame. Thigh muscle circumference, stifle range of motion, and internal tibial rotation in the operated limb were not significantly different from the preoperative measurements or the contralateral, unoperated limb. A caudal drawer motion was consistently present in the stifle joints with a transected CaCL. A radiographic evaluation of the operated stifle joints did not reveal osteoarthritic changes; four of seven stifle joints had an irregular fat pad 6 months after surgery. Results of a joint fluid analysis revealed a slight increase in synovial cells within treated stifle joints; inflammatory cells were not observed. The only gross morphologic change in stifle joints with a severed ligament was enlarged knobby remnants of the CaCL. Articular cartilage defects or osteophytes were not observed. Results of a histologic examination of the CaCL remnants revealed synovial cellular capping and intraligamentous fibroplasia. Based on a limited number of dogs, it was concluded that isolated transection of the CaCL produced minimal clinical and pathologic changes in the stifle joint during a 6 month period.

Evaluation of collagen as a retainer for autogenous cancellous bone used in repair of full thickness cortical bone defects.

A commercially available collagen sponge acting as a cylindrical retainer containing autogenous cancellous bone graft was proposed for treatment of full thickness cortical defects in dogs. Three groups of three dogs each were subjected to removal of at least 1.5 cm of the tibial diaphyses. All tibias were stabilized with bilateral external fixators. Group 1 received collagen surrounding an autogenous cancellous bone graft. Group 2 received collagen and group 3 received no treatment of the ostectomy site. The collagen sponge appeared to allow vascularization of the bone graft as evidenced by new bone formation and was resorbed by 3 months after implantation. Radiographic, histomorphologic, and histomorphometric evaluation at 3 months after surgery showed a greater per cent of bone in the ostectomy site in group 1.

Osteochondritis dissecans of the femoral head of a Pekingese.

An 8-month-old male Pekingese was admitted with a 1-month history of right hindlimb lameness and crepitation in the right coxofemoral joint. There was radiographic evidence of a focus of subchondral osteolysis of the right femoral head. The tentative diagnosis was avascular necrosis of the femoral head. The problem was corrected by femoral head ostectomy. Gross and microscopic examination of the femoral head resulted in a diagnosis of osteochondritis dissecans. Osteochondritis dissecans is an uncommon diagnosis both in small breeds of dogs and in the coxofemoral joint.

Preliminary study of ethylene oxide sterilization of full-thickness cortical allografts used in segmental femoral fracture repair.

Full-thickness canine cortical allografts were cleanly harvested, sterilized with ethylene oxide, and stored at room temperature. The allografts were incorporated into canine segmental femoral fracture repairs and compared clinically, radiographically, and morphologically with control femoral cortical autografts for function of the limb, graft acceptance, and bone union. Sterility was maintained and the cortical allografts were well accepted by the host animals, resulting in full use of the limb which was subjected to surgical operation. The allografts showed healing patterns similar to those of the autografts, as determined by radiographic, gross, and histologic evaluation of the proximal and distal host-graft interfaces. Evaluations were made monthly. The host-graft interfaces of the allografts and autograft were filled with woven bone with adjacent vascular invasion and remodeling of the graft at the final 4th-month evaluation.

Effects of serum, fibroblast growth factor, and platelet-derived growth factor on explants of rat tail tendon: a morphological study.

Eighteen tail tendon fascicles were explanted from a 40-day postpartum rat and maintained in both serum-supplemented and serum-free Eagle's minimal essential medium for 2 weeks. Epitendon and paratendon connective tissues were excluded from these explants. Tendon fibroblasts maintained in serum-supplemented medium proliferated and synthesized collagen. Tendon fibroblasts explanted in serum-free medium remained viable but did not proliferate. Fibroblast growth factor and platelet-derived growth factor were shown to stimulate proliferation of mature tendon fibroblasts in serum-free medium.

Effects of whole blood clots, time, and implant size on vascularization and collagen deposition along Teflon-ensheathed carbon fibers implanted in ewes.

Seventy-two subcutaneous implants were examined to evaluate connective tissue response to Teflon-ensheathed carbon fibers and whole blood clots. Carbon fibers significantly (P less than or equal to 0.001) increased vascularization and collagen formation within the Teflon sheath. Carbon fibers provide a potentially strong scaffold that would physically support cell migration during wound healing. However, obvious foreign body reactions occurred, which indicate that further studies on the biologic features of carbon fiber are needed before carbon fibers become entirely acceptable for long-term implantation. Compared with no-clot controls, Teflon tubes containing only whole blood clots stimulated a significant (P less than or equal to 0.001) wound-healing response, including organized collagen fiber formation. Other variables tested in this study such as length and diameter of the Teflon tubes did not significantly influence connective tissue responses.

In vitro analysis of ovarian differentiation and the initiation of meiosis in the rat.

Intact, cranial, and caudal portions of fetal rat gonads on days 13, 14, 15, 16 and 17 of gestation were cultured singly on Nucleopore filters in Eagle's MEM and McCoy's 5A media (both supplemented with fetal calf serum and glutamine) to evaluate the role of the mesonephros in mammalian gonadogenesis. After 2--7 days in culture, in vitro and in vivo control tissues were examined by light and electron microscopy to determine the extent of morphological differentiation and gonium maturation. The onset of morphological differentiation and meiotic activity, as determined by synaptonemal complex formation, was found to be independent of the mesonephric epithelium. Ovaries and testes were also cultured as heterologous pairs on opposite sides of collagen-coated Nucleopore filters for 4--6 days in McCoy's 5A media. In the absence of transfilter cellular migration and establishment of cell-to-cell contact, the in vivo pattern of sexual dimorphic onset of meiosis was observed. This finding lends support to the concept that local somatic-germ cell associations as opposed to extragonadal factors, are capable of providing the necessary environment for regulation of meiosis in the fetal rat.