Partial Maxillectomy in the Dog Comparison of Suture Materials and Closure Techniques

This study compares the healing of oronasal defects created by partial maxillectomy when closed using two different suture materials and two different suture patterns. In experiment 1, 24 dogs were divided into four equal groups. Partial maxillectomy was performed on each dog and was closed using either a two-layer simple interrupted suture pattern (12 dogs) or a modified Mayo mattress pattern (12 dogs) with either polyglactin 910 (12 dogs) or polypropylene (12 dogs) sutures. On the seventh postoperative day, the dogs were euthanized, suture line bursting pressures were measured, and wound healing was evaluated grossly and histopathologically. Suture line dehiscence occurred in one dog from each of the four groups. These were the only dogs in which electrocoagulation had been used. The healing of suture lines closed with the two-layer simple interrupted pattern was superior to that of those closed with the modified Mayo mattress pattern based on the degree of gross oral ulceration, suppurative inflammation, fibrosis and oral epithelial covering at the suture line, and the number of necrotic sites in the adjacent tissue. The healing of suture lines closed with polypropylene was superior to that of those closed with polyglactin 910 based on suture line bursting pressures and the degree of suppurative inflammation and tissue necrosis at the suture sites. In Experiment 2, partial maxillectomies were performed on four dogs, and closure was achieved using a two-layer simple interrupted suture pattern with either polyglactin 910 (two dogs) or polypropylene (two dogs). On the 30th postoperative day, the dogs were euthanized, and wound healing was evaluated grossly and histopathologically. All suture lines were well healed. All polyglactin 910 oral sutures were absent, while all polypropylene oral sutures were still present.     

Comparison of the healing of prescrotal urethrotomy incisions in the dog: sutured versus nonsutured

Comparison was made of the healing of sutured prescrotal urethral incisions (12 dogs) with that of nonsutured incisions (6 dogs). Comparison was also made of the healing of 5-0 polyglactin 910-sutured urethral incisions (6 dogs) with that of 5-0 polydioxanone-sutured incisions (6 dogs). Three dogs from each treatment group were euthanatized 3 weeks and 6 weeks after the surgical procedure. Surgical sites were examined grossly, and urethral circumference measurements were taken at 3 locations (surgical site, 1 cm cranially, and 1 cm caudally). Transverse sections of the surgical sites were prepared and examined by light microscopy. Hemorrhage occurred postoperatively in dogs in which the incisions were not sutured. The surgical sites from the 6 dogs in which incisions healed by second intention had more fibrosis and less inflammation than did those that were sutured. There was little difference between incisions sutured with polyglactin 910 and those sutured with polydioxanone suture material. Postoperative urethral stricture formation did not occur in any of the dogs.     

In vitro comparison of mechanical and degradation properties of equivalent absorbable suture materials from two different manufacturers

Objective: To compare the mechanical, knotting, and absorption properties of 3 synthetic absorbable suture materials (polyglactin 910, polydioxanone, poliglecaprone 25) from 2 different manufacturers (Huaiyin Medical Instruments Co. Ltd. and Ethicon Inc.). Sample Population: Suture material samples from the same manufacturing lot for each suture type and manufacturer. Methods: Part 1: 10 samples of each suture were incubated in bovine serum and tested for ultimate load and stiffness at days 0, 1, 7, 14, 21, and 28. Part 2: 10 knotted samples were similarly evaluated, without incubation. Results: Huaiyin polydioxanone had a greater (P<.001) ultimate load on days 0, 1, and 7; and a consistently greater stiffness for the duration of the study, compared with the Ethicon polydioxanone. Ethicon poliglecaprone 25 had a greater ultimate load on days 0, 1, 7 (P<.001); on day 21 Huaiyin had a greater ultimate load. Ethicon poliglecaprone had greater stiffness on days 0, 1, 7 (P<.001). Ethicon polyglactin 910 had a greater (P<.001) ultimate load at all times and a greater stiffness (P<.001) at days 0, 1, 7, and 14 compared with Huaiyin polyglactin 910. Huaiyin polydioxanone and polyglactin 910 had greater knot breaking strengths than Ethicon equivalents (P<.001). Conclusion: Differences in mechanical properties exist between nominally identical suture materials from different manufacturers.     

Surgical repair of deep melting ulcers with porcine small intestinal submucosa (SIS) graft in dogs and cats

PURPOSE: To evaluate the efficacy of using a porcine small intestinal submucosa (SIS) graft for the surgical repair of deep melting ulcers in dogs and cats. METHODS: Two cats and five dogs presented with deep and large melting ulcers of the cornea. In each case, the necrotic and collagenolytic tissue of the cornea was removed by keratectomy. A SIS graft, 1 mm greater than the corneal defect, was rehydrated in sterile saline and sutured to the edges of the ulcer with a simple interrupted pattern of 9/0 polyglactin 910. A nictitating membrane flap was utilized in two cats and four dogs for 2 weeks. All cases were treated postoperatively with topical and systemic antibiotics, a systemic anti-inflammatory drug and topical atropine. All animals were re-evaluated 15 days, 4 weeks, 35-45 days, 2-3 months and 6 months postsurgery. RESULTS: At 15 days postsurgery, a superficial intense corneal neovascularization surrounded the SIS graft. No ocular discomfort was present and fluorescein staining was negative in all cases. At 4 weeks the SIS graft was thick and opaque in all cases, although in one cat the SIS graft had partially detached. Between 35 and 45 days, SIS graft integration was evident in all eyes, and corneal neovascularization had decreased progressively. All eyes healed without complications and retained corneal transparency. This occurred even in the presence of corneal perforation in two cases: one prior to and one during surgery. CONCLUSION: Results of our study suggest the SIS graft may be an effective alternative surgical treatment to the traditional conjunctival grafts commonly used to repair melting ulcers in dogs and cats. The advantages of using a SIS graft include good corneal transparency, preservation of corneal integrity and maintenance of vision.     

A mechanical study of ligature security of commercially available pre-tied ligatures versus hand tied ligatures for use in equine laparoscopy

OBJECTIVE: To determine a hand-tied ligature knot configuration, suture size, and suture type that would be an acceptable substitute to commercially available ligature knots for use in equine laparoscopic surgery. STUDY DESIGN: Three-factor ANOVA with the fixed effects being suture type, suture size, and knot type. The dependent variable was ligature security (load to failure). METHODS: Commercially available Endoloop and 4 hand-tied slipknot ligatures were compared with a 4-layer square knot. The hand tied ligature knots tested were the 4S modified Roeder knot, the Brooks knot, the modified Roeder knot, and the Weston knot. Two suture sizes (0, 2) of each of 2 suture types (polydioxanone, polyglactin 910) were tested with each hand tied knot. Two types (polydioxanone, polyglactin 910) of size 0 Endoloop were tested. Twenty repetitions of each knot suture type were tested for force to yield on a materials testing machine. Statistical analysis consisted of a 3-way ANOVA with individual comparisons made using the Bonferroni method. Significance was P< or = .05. RESULTS: Only the 4S modified Roeder knot in 2 polydioxanone (103 N) was comparable with the breaking strength of the square knots (157 N). All other knot suture combinations tested were significantly weaker than the square knot (range, 2-18 N). CONCLUSION: For equine laparoscopy, a 2 polydioxanone 4S modified Roeder knot would be an acceptable alternative to the commercially available Endoloop. CLINICAL RELEVANCE: Laparoscopic slip knots are commonly used in equine laparoscopic surgery. Various knot configuration and suture size and type combinations will affect the security of the slip knot.     

Corneal sensitivity and aqueous tear production in dogs undergoing evisceration with intraocular prosthesis placement

OBJECTIVE: To determine whether there is an association between evisceration with intraocular prosthesis placement via a dorsal scleral approach and decreased corneal sensitivity or aqueous tear production in dogs. DESIGN: Prospective study. PROCEDURE: Twenty-one dogs scheduled to undergo unilateral evisceration with intraocular prosthesis, and with a normal normotensive contralateral eye, based on slit-lamp biomicroscopy, indirect ophthalmoscopy and applanation tonometry, were included in the study. Central corneal sensitivity was measured with a Cochet-Bonnet esthesiometer prior to (week 0) and 2, 7, 14 and 28 weeks following surgery. Other pre- and postoperative data collected were Schirmer's tear test (STT I), Schirmer's tear test with topical anesthesia (STT II), corneal fluorescein retention, and intraocular pressure (IOP; postoperative control eye only). Axial globe length was determined for both eyes. Scleral incision length in the surgery eye was also recorded. RESULTS: Corneal sensitivity was significantly lower in eyes undergoing evisceration with intraocular prosthesis than in control eyes both preoperatively and postoperatively at all time points. There was no significant difference between preoperative and postoperative corneal sensitivity within the two groups. There was no significant difference in STT I or STT II-values between control eyes and surgery eyes preoperatively. There was a significant difference between preoperative and 2-week postoperative STT I in the surgery eye. There was a significant difference between the preoperative and 28-week postoperative STT II in the surgery eye. The 28-week postoperative STT I-values differed significantly between control and surgery eyes. Corneal sensitivity tended to decrease with increased degree of buphthalmos or with increased scleral incision length, although neither relationship was statistically significant. CONCLUSIONS: Eyes that have sustained chronically elevated intraocular pressure had decreased axial corneal sensitivity compared to normal eyes, which persisted even after intraocular pressure was reduced. The presence of buphthalmos appeared to be a factor in globes developing decreased corneal sensitivity. Evisceration via a dorsal scleral incision did not result in a significant further reduction in axial corneal sensitivity. A mild reduction in aqueous tear production occurred over time in globes following evisceration with intraocular prosthesis.     

Clinical Experience With Polydioxanone Suture Material

Polydioxanone (PDS™) synthetic absorbable suture material was evaluated in 169 dogs and cats. Sutures or ligatures were used on 446 tissues including 18 contaminated and 16 infected wounds. There was less tissue friction than with polyglycolic acid or polyglactin 910 sutures. The suture tended to kink during placement of continuous suture patterns. There was one wound dehiscence.
Polydioxanone may be used wherever surgical gut, polyglycolic acid, or polyglactin 910 sutures are normally used.     

Effects of Nylon and Polyglactin 910 Suture Material on Perilimbal Corneal Wound Healing in the Dog

The effects of fine suture materials on corneal wound healing in the dog were studied. In 20 dogs, standardized perforating perilimbal clear corneal wounds were made and closed with either monofilament Polyglactin 910 or nylon. Five dogs each were euthanized 8,12,16, and 21 days postoperatively. Results of gross, biomicroscopic, and histologic examinations at 8,12,16, and 21 days showed nylon and Polyglactin 910 to cause similar inflammatory responses. Epithelialization and suppuration around the suture tracts were observed more frequently when Polyglactin 910 was used. Both materials were associated with a foreign body (granulomatous) response. There was no loss of wound integrity with either material. Strengths of the incised corneal tissues with and without the sutures intact were determined. At day 16 postsurgery, there was a statistically significant difference in tissue strengths between cases in which sutures were and were not intact. This difference was not apparent at 21 days postsurgery, which suggested that the suture dependent phase ends between the 16th and 21st postsurgical days. In addition, at day 16 there was no statistical difference between the tissue strength of wounds sutured with nylon or Polyglactin 910. Corneal suture materials studied should remain in place for at least 16 days, and absorbable material is only appropriate if it retains tensile strength for 16 days.     

The Effect of Six Knotting Methods on the Biomechanical Properties of Three Large Diameter Absorbable Suture Materials

Objective— To evaluate the effect of 6 different knotting methods on the mechanical properties of 3 large absorbable suture materials used in large animal surgery. Study Design— In vitro mechanical study. Sample Population— Knotted suture loops (n=15 per group). Methods— Suture loops were created between two low‐friction pulleys with either 2 polydioxanone, 2 polyglactin 910 or 3 polyglactin 910. Strands were tied using 1 of 6 knotting technique: square knot, surgeon knot, clamped surgeon's knot, sliding half‐hitch knot (HH), Delimar knot and self‐locking knot (SLK). A single cycle to failure test was performed on each suture loop with a distraction rate of 100 mm/min. Failure modes were evaluated and breaking strength, elongation to failure and stiffness were compared. Results— All loops except two HH failed at the knot by acute breaking. The double‐stranded SLK was both stronger and stiffer than all other knots for each suture material. Clamping the first throw of the surgeon knot decreased load to failure significantly (143.11 ± 8.64 N) compared with not clamping (159.21 ± 6.14 N) for polydioxanone. Stiffness and elongation to failure were respectively lower and increased for 2 polydioxanone compared with both polyglactin 910 materials for all knotting techniques. Conclusions— Knotting techniques do influence structural properties of suture loops. The double strand loop conferred stiffer and stronger properties to the SLK Clinical Relevance— Clamping the first throw of polydioxanone should be avoided when tying a suture under tension even using large diameter suture materials. Using a SLK might be considered as a useful alternative when excessive tension is present.     

In vitro bursting pressures of jejunal enterotomy closures in llamas

OBJECTIVE: To evaluate closure strength (in vitro bursting pressure) of jejunal enterotomies in llamas. STUDY DESIGN: In vitro experimental study. SAMPLE POPULATION: Jejunal specimens (n=72) from 6 llamas. METHODS: Differences in bursting pressures and luminal diameters were compared between 2 layer enterotomy closures with an initial full thickness simple continuous pattern oversewn with either a continuous Lembert or Cushing suture pattern using 3 sizes (2-0, 3-0, 4-0) of polyglactin 910 and polydioxanone. RESULTS: Bursting pressures were significantly higher for enterotomies closed with polydioxanone than polyglactin 910, independent of suture size, but there was no difference between Lembert and Cushing oversew patterns. Use of a Lembert pattern reduced intestinal diameter more than a Cushing pattern regardless of suture material or size. CONCLUSIONS: Although polydioxanone resisted higher bursting pressures than polyglactin 910, both suture materials should be considered satisfactory for jejunal enterotomy closure in llamas based on typical intraluminal pressures expected in clinical patients. The optimal oversew pattern may be continuous Cushing to maximize the luminal diameter in small intestinal enterotomy closures. CLINICAL RELEVANCE: In vitro bursting pressures may help to predict which enterotomy sites would leak post-operatively, although further studies are necessary to determine the outcome in clinical patients.     

Comparison of gross and histologic tissue responses of skin incisions closed by use of absorbable subcuticular staples, cutaneous metal staples, and polyglactin 910 suture in pigs

OBJECTIVE: To assess gross and histologic tissue responses of skin incisions closed by use of absorbable subcuticular staples, cutaneous metal staples, and polyglactin 910 suture in pigs. ANIMALS: 8 purpose-bred disease-free pigs. PROCEDURE: Pigs were randomly allocated to 1 of 4 groups from which tissues were collected after death on postoperative days (PODs) 7, 14, 21, or 42. In each pig, 4 incisions were made; 1 was closed subcuticularly with 3-0 polyglactin 910 suture, 1 was closed with metal staples, and 2 were closed with absorbable subcuticular staples. Incision sites were grossly evaluated every 3 days after closure. At necropsy, incision sites and surrounding tissues were examined histologically; a histopathologic scoring system was used to quantitate healing and tissue response directed against the closure material. RESULTS: Postoperatively, the metal staples induced a severe inflammatory response, compared with minimal inflammation associated with the suture or absorbable subcuticular staples. Histologic evaluation of incisions on PODs 7, 14, and 21 revealed less severe inflammation associated with absorbable subcuticular staples than that associated with the other materials. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that absorbable subcuticular staples induced a less severe inflammatory response in the early stages of healing in pigs, compared with other commonly used methods of wound closure. Use of absorbable staples potentially combines the benefits of subcuticular closure with the speed and precision of staple placement.     

Amniotic membrane transplantation for the treatment of feline corneal sequestrum: pilot study

Objectives To describe and evaluate the use of equine amniotic membrane trans‐plantation after lamellar keratectomy for the treatment of corneal sequestrum in cats. Methods Six cats (seven eyes) of various breed and ages with corneal sequestra were treated surgically with lamellar keratectomy and amniotic membrane transplantation. All the sequestra and a small piece of the amniotic membranes used for each surgery were submitted for histopathologic examination. Results Five of the seven eyes showed minimal level of scarring in the cornea and good transparency. No recurrences of the sequestra have been noted during the follow‐up period (3–9 months). One eye had necrosis of the amniotic membrane 2 weeks after the surgery. The sequestrum of this eye showed a high level of bacterial contamination on histopathology. Three months later the same cat developed a descemetocele in the area where the necrotic amniotic membrane was rejected. A second eye developed a perforation under the amniotic membrane two weeks after the surgery. The sequestrum of this eye was deep and without vascularization. Conclusion Amniotic membrane transplantation after lamellar keratectomy was a valid procedure for surgical treatment of corneal sequestrum in cats. The procedure resulted in excellent cosmesis and functional vision in five of seven eyes; although case selection is important, particularly to exclude the very deep and non‐vascularized sequestra.     

Difference in incisional complications following exploratory celiotomies using antibacterial‐coated suture material for subcutaneous closure: Prospective randomised study in 100 horses

Reasons for performing study: Incisional complications are a major post operative challenge following ventral midline exploratory celiotomy for abdominal pain in horses. They lead to discomfort, prolonged hospitalisation, longer recovery times and increased cost; therefore, investigation of preventative procedures are warranted. Objectives: To determine the clinical effect of antibacterial (triclosan) coated 2‐0 polyglactin 910 suture material on the likelihood of incisional infections when used for closure of subcutaneous tissue following ventral midline celiotomies in horses. Methods: One hundred horses undergoing exploratory celiotomy assigned at random to one of 2 groups. In the control group coated 2‐0 polyglactin 910 (Vicryl) was used for apposition of the subcutaneous tissue in a simple continuous pattern and, in the study group, antibacterial (triclosan) coated 2‐0 polyglactin 910 suture material (Vicryl Plus) was used. Post operatively an elastic adhesive abdominal bandage was applied, changed and the incision was inspected by a clinician blinded to the study protocol at 24–36 h and 6–9 days post operatively. Outcomes of interest were evidence of incisional pain, incisional oedema, sheath/udder oedema, incisional drainage, hernia formation and dehiscence. Results: Antibacterial‐coated suture material did not decrease the likelihood of incisional complications in 100 horses. Conclusions: A beneficial effect on ventral midline incisions in 100 horses was not evident by using antibacterial‐coated suture material. Potential relevance: Lack of effectiveness of antibacterial‐coated suture material in equine ventral midline closure after exploratory celiotomy and the observed potential adverse effects suggest that further clinical investigations are needed before using such material routinely on horses.     

Cullen frontal sinus valved glaucoma shunt: preliminary findings in dogs with primary glaucoma

PURPOSE: To evaluate the efficacy of a novel, professionally manufactured, frontal sinus valved glaucoma shunt in maintaining normal intraocular pressure (IOP) and vision in dogs with primary glaucoma. METHODS: Three eyes of three dogs diagnosed with primary glaucoma were included in this prospective clinical study. A Cullen frontal sinus valved glaucoma shunt was implanted into each glaucomatous globe. Dogs were treated postoperatively with topical neomycin/polymyxin B/0.1% dexamethasone and 0.03% flurbiprofen every 6 h tapered over 8-12 weeks, and meloxicam at 0.1 mg/kg orally every 24 h for 7-10 days. IOP, intracameral shunt position and apparent patency, and vision were assessed twice daily for up to 4 (n= 3 eyes) and 10 (n= 2 eyes) days postoperatively, and then at re-examination periods of up to 36 weeks (n= 1 eye). Postoperative complications were recorded and documented photographically. RESULTS: Normal IOP was maintained in all shunted globes (range 10-29 mmHg; mean = 16.7 mmHg at 24 h; IOP = 23 mmHg at 36 weeks) postoperatively for 2 days (3/3 eyes), 8 weeks (2/2 eyes), and 36 weeks (1/1 eye) without additional antiglaucoma therapies. Photopic vision and shunt position and patency were maintained in all shunted globes for all follow-up periods. Postoperative complications included mild aqueous flare and fibrin (n= 3 eyes for 3-10 days postoperatively); intracameral shunt occlusion with fibrin (n= 1 eye at days 2 and 4); partial anterior chamber tube extrusion (n= 1 eye at day 4), and focal corneal edema (n= 1 eye at 18 weeks). Tissue plasminogen activator injected intracamerally through the silicone tube near the frontal sinus effectively resolved the fibrinous shunt occlusion. CONCLUSIONS: The Cullen frontal sinus valved glaucoma shunt shows promise for the management of canine primary glaucoma.     

An in vitro biomechanical comparison of the breaking strength and stiffness of polydioxanone (sizes 2, 7) and polyglactin 910 (sizes 3, 6) in the equine linea alba

OBJECTIVE: To determine failure strength, stiffness, and failure mode of 4 suture materials in equine linea alba. STUDY DESIGN: Randomized complete block design. SAMPLE POPULATION: Linea albas collected from 12 adult horses (mean weight, 475 kg; mean age, 10 years). METHODS: The ventral abdominal fascia, including the linea alba, was collected and bisected along the linea alba into right and left halves. Each half was divided into four, 5-cm sections extending from the umbilicus cranially, and randomly assigned to 1 of 4 suture materials: 2 polydioxanone (2 PD), 3 polyglactin 910 (3 PG), 6 polyglactin 910 (6 PG), and 7 polydioxanone (7 PD). A single cycle to failure test was performed on each specimen at a distraction rate of 100 mm/min. Differences in failure strength and stiffness for the materials were evaluated using a mixed linear model with significance set at P<.05. RESULTS: In 94 of 96 test sections, constructs failed by suture failure. There were significant differences in failure strength (P<.0001) and stiffness (P<.001) among the suture/tissue constructs. 7 PD had the highest breaking strength (316.8 N) followed by 6 PG (281.3 N), 3 PG (229.9 N), and 2 PD (193.0 N). Six PG had the largest stiffness (14 N/mm) followed by 3 PG (12.7 N/mm), 7 PD (10.1 N/mm), and 2 PD (7.2 N/mm). Suture breaking strength and stiffness were not affected by linea or fascia thickness, individual horse, half of the linea alba, or abdominal wall position. Eighty-five (90.4%) suture loops failed adjacent the knot. CONCLUSIONS: When tested in single cycle to failure, suture material was more likely to fail than the linea alba. Larger suture materials had higher breaking strengths than smaller suture materials and stiffness was also affected by suture material and size. CLINICAL RELEVANCE: Given its high initial breaking strength and its relatively longer in vivo strength retention, 7 PD seems an appropriate choice of suture material for closure of the equine linea alba when maximal short-term failure strength is desired.     

Survey of conjunctival flora in dogs with clinical signs of external eye disease

Bacteria were isolated 68% of the time from the conjunctival sacs of 120 dogs with conjunctivitis, blepharitis, dacryocystitis, or corneal ulcerations. Coagulase-positive Staphylococcus aureus was the most frequently isolated organism (68%); when both eyes were affected, S aureus was recovered from 29% of the dogs; and in dogs with 1 eye affected, S aureus was isolated from 23% of the affected eyes and in 18% of the nonaffected eyes. Other organisms recovered from eyes were coagulase-negative Staphylococcus epidermidis (27%), beta-hemolytic streptococcus (19%), alpha-hemolytic Streptococcus (17%), Escherichia coli (10%), Bacillus spp (11%), and Proteus spp (7%). It was concluded that S aureus may appear as a primary pathogen in ocular disease. When 1 eye is clinically affected, S aureus can be a potential invader of the normal eye.     

In Vitro Loss of Tensile Strength and Elasticity of Five Absorbable Suture Materials in Sterile and Infected Canine Urine

The loss of breaking strength and elasticity of five absorbable suture materials (polydioxanone [PDS-II], polyglycolic acid [PGA], polyglactin 910 [PG-910], polyglyconate [GTMC], and chromic gut) after in vitro incubation in sterile, Escherichia coli- and Proteus mirab/tfs-inoculated canine urine was studied. Biomechanical testing, in a controlled environment, was performed during the 28-day study period. Polydioxanone and chromic gut retained greater than 90% of their original strengths after 28 days of incubation in sterile urine and 87% of original strengths in E. co//-inoculated urine. Polyglyconate retained 24% and 18% of original strength, respectively, after incubation in sterile and E. co/i-inoculated urine for 28 days. Polyglycolic acid and PG-910 retained less than 30% of original strength in sterile urine and only 7% in E. co/i-inoculated urine after 21 days of incubation. In P. m/rabi/is-inoculated urine, loss of tensile strength and elongation was significant for all suture materials. Polyglycolic acid and PG-910 lost all strength after 24 hours of incubation. Polydioxanone lost all strength after 7 days of incubation, whereas GTMC retained 19% at day 7. Chromic gut retained 78% at day 7 and 16% after 21 days of incubation, however, the absence of normal phagocytic destruction of chromic gut in this in vitro study may have artificially elevated these values. In sterile urine with chemically modified pH, loss of strength and elongation was greater in alkaline urine than in neutral or acidic urine for all types of suture materials.     

Knot Security of Suture Materials

The knot security of chromic gut, polyglycolic acid, polyglactin 910, polydioxanone, polypropylene, and monofilament nylon size 2-0 suture materials were tested biomechanically in vitro. Twenty reproducible knots were tied and incubated in canine serum at 37 degrees for 24 hours before testing. A "secure knot" was defined as a knot that, when tested to failure, broke rather than untied by slippage. The minimum number of throws necessary to make a secure, snug (1500 g tension) square knot was three for gut, polyglycolic acid, polyglactin 910, and polypropylene and four for polydioxanone and nylon. All throws including the first were counted. With all suture materials tested, surgeon's knots were as secure as square knots. Only gut, polyglycolic acid, and polydioxanone granny knots were as secure as square knots; no loosely tied (500 g tension) asymmetric square knots were as secure as snug square knots, and only polydioxanone and polypropylene loose square knots were as secure as snug square knots. Square knots used to start a continuous pattern required one additional throw with gut, polydioxanone, and nylon. Square knots used to end a continuous pattern required two to three additional throws with all materials tested.     

A keratoprosthesis prototype for the dog

Objective  To describe the technique for implantation of a novel keratoprosthesis (KP) prototype and evaluate its application for the treatment of corneal blindness in dogs.
Animals studied  Seven dogs, all of them being clinically blind before surgery as a result of severe corneal endothelial disease (5/7) or chronic superficial keratitis (2/7) that were unresponsive to prior therapy.
Procedures  A silicone KP was implanted unilaterally, just anterior to Descemet's membrane, after creating a stromal pocket by deep stromal lamellar dissection.
Results  Implantation of the KP was accomplished without complication in six of seven operated dogs. In the remaining case, an intra-operative complication (perforation of Descemet's membrane) was associated with extrusion of the KP 8 weeks postoperatively. All operated eyes regained limited vision after surgery. Three to six months after implantation purulent keratitis occurred in all five eyes with endothelial disease, necessitating surgical removal of the KP 6 months postoperatively in 5/7 eyes.
Conclusions  This KP prototype shows promise as a treatment for certain blinding corneal diseases. However, changes in the design of this KP, allowing improved stromal integration, will be necessary before its clinical application can be approved.     

Repair of urethral defects using fascia lata autografts in dogs

OBJECTIVE: To evaluate the feasibility of urethroplasty using a free fascia lata (FL) graft in the dog. STUDY DESIGN: In vivo experimental study. ANIMALS: Mixed-breed dogs (n=14). METHODS: Half of the circumference of the urethra, approximately 1.5 cm long, was excised in 14 male dogs to induce a urethral defect. FL (approximately 2 cm x 2 cm) harvested from the lateral thigh was sutured to the urethra using a 3-0 polyglactin 910 continuous pattern. Dogs were monitored daily for bladder distention and had urethral catheters until normal voiding was observed. On day 60, each dog had a positive contrast urethrogram, and then 8 dogs were euthanatized for gross and histologic examination. Six dogs were monitored for urologic problems for 6 months, and a positive contrast urethrogram was repeated. RESULTS: All dogs recovered successfully; 4 dogs had difficulty voiding for 2-3 days and urine was aspirated from these dogs every 3 hours until signs of painful urination disappeared. On positive contrast urethrograms, urethral anatomy was considered normal except in 4 dogs that had an irregular contour. Gross urethral examination confirmed an absence of ulceration, stricture, diverticula, or fistula formation, and the FL-lined graft survived in all dogs. No degenerative and reparative responses were observed. On histologic examination of the penile urethra, the lumen was intact, covered with transitional epithelium, and surrounded by corpus spongiosum with cavernous spaces and blood-filled vessels. CONCLUSIONS: Free FL grafts are incorporated satisfactorily and would appear to be useful for repairing urethral defects. CLINICAL RELEVANCE: FL grafts should be considered for repair of urethral defects in dogs.