Feasibility of implant driven micturition in paraplegic dogs.

OBJECTIVE: This study evaluates the feasibility of using existing technology for implant driven micturition in paralyzed dogs (part I) and also examines a less invasive technique for implant driven micturition (part II). STUDY DESIGN: Part I. Sacral nerve root dimensions and bladder and urethral pressure responses to intradural and extradural sacral nerve root stimulation were measured to determine the optimal location and size for sacral nerve root electrodes. Part II. Sacral nerve roots were stimulated via wire electrodes introduced into the S2 foramina. ANIMALS OR SAMPLE POPULATION: Ten dogs (five dogs in part I and five dogs in part II). METHODS: Part I. Microtip pressure transducers were used to monitor bladder and urethral pressure responses to sacral nerve root stimulation with tripolar hook electrodes. After euthanasia, sacral nerve root, and spinal canal dimensions were measured. Part II. Bipolar electrical stimulation of the sacral nerve roots was performed by introducing wire electrodes into the S2 foramina. Bladder and urethral pressures were recorded as in part I. RESULTS: Part I. Stimulation of SI produced an increase in urethral, but not bladder, pressure. Stimulation of S2 or S3 produced increases in bladder pressure and decreases in urethral pressure. Intradural and extradural nerve roots were not significantly different with respect to nerve dimensions or effects on nerve stimulation. Part II. High bladder pressures were achieved, but effective voiding could not be produced, primarily because of urethral resistance. CONCLUSIONS: Part I. Extradural implantation was determined to be the most appropriate site based on ease of dissection, nerve root dimensions, and decreased risk of iatrogenic trauma. Enough space is available to implant two to four tripolar spiral nerve cuffs. Part II. Transforaminal sacral nerve root stimulation did not effectively empty the bladder. CLINICAL RELEVANCE: Clinical trials in paraplegic dogs are necessary to evaluate the number of sacral nerve cuff electrodes necessary to produce effective bladder emptying.

Mast cell tumour destruction in dogs by hypotonic solution.

Distilled water was studied as an hypoosmotic oncolysis agent to prevent mast cell tumour (MCT) recurrence following surgical excision. The results from 118 MCTs excised in 74 dogs were: surgery alone, a recurrence rate of 52.6 per cent (10/19); and surgery followed by distilled water injections into the wound, a 26.2 per cent (26/99) recurrence rate. All of 10 small MCTs (0.03 to 0.25 cm3) injected with distilled water in situ with no surgery, regressed. The present data suggest that distilled water should be considered as an adjunct to surgery for canine MCTs.

Flow study of surgical coronary artery fistula as an alternative to sequential bypass.

Surgical coronary artery fistula, in which the last anastomosis is created to a low-pressure cardiac chamber, was recently introduced as an alternative method to improve graft flow and patency in a sequential graft when coronary arteries are small or diffusely diseased. To assess graft flow, effect on haemodynamics, flow distribution and to determine proper size of the distal anastomosis, a saphenous vein was sequentially anastomosed from the ascending aorta to the left anterior descending artery and then to the left atrium in eight mongrel dogs. Graft flow was measured before and after opening the fistula to the left atrium between the ascending aorta and left anterior descending artery (flow A) and between the left anterior descending artery and left atrium (flow B). Left atrium pressure and systolic left ventricular pressure (mmHg) were recorded. The diameter of the distal anastomosis was regulated with a bulldog clamp. When distal anastomosis was at 2.5-3 mm mean(s.d.) flow A increased from 64.5(19.5) to 134.7(28.5) ml/min (P < 0.01) without significant left atrial pressure or left ventricular pressure change. With a distal anastomosis of 4 mm or more, flow A increased from 69.8(19.9) to 396.1(62.2) ml/min (P < 0.001). Left atrial pressure increased from 5.6(1.0) to 6.1(0.9) mmHg (P < 0.05) without a change in left ventricular pressure. In both sizes of distal anastomosis, flow to the left anterior descending artery did not change either before or after the shunt (flow B) was opened. Neither volume loading, rapid atrial pacing, neosynephrine or epinephrine infusions caused deleterious haemodynamic effects with the shunt open.(ABSTRACT TRUNCATED AT 250 WORDS)

Flow study of coronary-coronary bypass grafting.

Coronary-coronary bypass grafting was recently introduced for patients with either calcification of the ascending aorta or an inadequate length of graft. Flow in the coronary-coronary bypass graft and that in aortocoronary bypass to the same coronary bed was compared in eight mongrel dogs. Flow reserve of the proximal right coronary artery as a donor vessel to the coronary-coronary bypass graft was also measured. Both a coronary-coronary and aortocoronary bypass were constructed to the proximally ligated left anterior descending artery. The flow in each graft was measured with the other graft temporarily occluded. Flow reserve of the right coronary artery (mean internal diameter 1.5mm) proximal to the anastomosis was measured before and after opening of the coronary-coronary bypass. Mean(s.d.) flow as 50.0(12.3) ml/min in the coronary-coronary bypass graft and 54.9(14.8) ml/min in the aortocoronary bypass, which was not significantly different. Flow curve studies demonstrated early systolic flow reversal in the aortocoronary bypass, while the coronary-coronary bypass showed only forward flow. Mean(s.d.) flow in the proximal right coronary artery increased from 35.4(11.8) to 76.0(15.3) ml/min after opening the coronary-coronary bypass graft, which had a flow rate of 42.2(10.4) ml/min. It is concluded that the coronary-coronary bypass graft can provide nearly the same flow rate as aortocoronary bypass, and that the proximal right coronary artery has sufficient flow reserve for this technique.

Enhanced ventricular recovery from high dose glucose, insulin and potassium with cardiopulmonary bypass support prior to cardioplegic arrest.

The concept that a beneficial preconditioning effect in ventricular recovery exists using high dose glucose (0.5 mg/kg), insulin (0.3 unit/kg), and potassium (0.2 mmol/kg) (GIK) with 20 min of normothermic cardiopulmonary bypass support (CPB) prior to 60 min of cardioplegic arrest (CA) was tested using 32 mongrel dogs divided into four subset test groups. Group 1 was given GIK and 20 min of CPB prior to CA, Group 2 was given GIK systemically over 10 min but no CPB prior to CA, Group 3 underwent 20 min of CPB without GIK and Group 4 was the control group with no GIK and no CPB assist. To focus specifically on in vivo ventricular recovery, dP/dT (mmHg/sec), developed pressure (dP) (mmHg), and segmental shortening (SS) (%) were measured prior to CPB, then 15, 30, 60, and 90 min after weaning from CPB, while left atrial pressure was kept constant. The average dP/dT (% recovery) at 60 min in Group 1 was 1,454 (122%) and significantly higher (P < or = 0.05) than Groups 2: 1,189 (99%), 3: 1,027 (79%) and 4: 1,030 (82%). Developed pressure at 90 min (% recovery) in Group 1, 88 (111%) was also better than Groups 3, 74 (86%), and 4, 72 (87%) (P < or = 0.05). Segmental shortening (% recovery) at 30 min was better in Group 1 (94%) than in Groups 2 (59%), 3 (73%) and 4 (68%). We conclude that GIK added to 20 min of CPB support prior to cardioplegic arrest enhances post CPB ventricular recovery and weaning from CPB.

Mast cell tumor destruction by deionized water.

In a controlled study, malignant murine P815 mastocytoma cells exposed in vitro to distilled and deionized water died as a result of progressive swelling, degranulation, and membrane rupture. A 90% mean cell death occurred when cells obtained directly from culture were exposed to deionized water for 2 minutes. Of 6 cryopreserved malignant murine cell lines, which included Cloudman S91 melanoma, CMT-93 rectum carcinoma, MMT-06052 mammary carcinoma, and S-180 Sarcoma, only P815 mastocytoma and YAC-1 lymphoma were significantly (P less than 0.05) affected by hypotonic shock; Cloudman S91 melanoma cells were the most resistant. Mastocytoma cells were selectively killed by hypotonic solution, and lymphoma cells were also killed by isotonic saline solution. Local mast cell tumor (MCT) recurrence and percentage survival were evaluated in 12 cats (21 MCT) and 54 dogs (85 MCT) subjected to surgery alone or local infiltration of deionized water as an adjunct to surgery. Of all 16 incompletely excised MCT in cats, there was no local recurrence following injection. Four mast cell tumors (2 cats) regressed after being injected in situ. In dogs with clinical stage-I MCT, local recurrence was detected in 50% (5/10), but with injection after incomplete excision, local MCT recurrence was significantly (P less than 0.05) less (6.6%, 1/15). Percentage recurrence was significantly (P less than 0.05) less and survival significantly greater when incompletely excised grade-II MCT were injected. Mean follow-up period after surgery in cats and dogs was 35 and 23.4 months, respectively.

Cystotomy closure. A comparison of the strength of appositional and inverting suture patterns.

Dorsal cystotomies were performed in 60 healthy dogs. Twenty bladders were closed with a single-layer interrupted appositional suture pattern, 20 with a two-layer interrupted appositional suture pattern, and 20 with a two-layer continuous inverting suture pattern. Four dogs from each group were euthanatized at hours 0, 3, 12, 18, and 24. Mechanical strength of the cystotomy closures was evaluated by calculating the circular bursting wall tension. The single-layer interrupted appositional suture pattern was as strong as both two-layer suture patterns at hours 3, 12, 18, and 24. The two-layer interrupted appositional suture pattern was as strong as the two-layer continuous inverting suture pattern during the first 24 hours.

Postoperative mediastinitis: a comparison of two electrocautery techniques on presternal soft tissues.

Postoperative mediastinitis remains a serious surgical problem, complicating 0.4% to 5% of all cases. In an experiment designed to address this problem, 36 mongrel dogs underwent a median sternotomy incision. In group I (n = 18) all layers to the sternum were opened by a scalpel, and electrocautery was used only for pinpoint hemostasis. In group II (n = 18) the skin was opened by a scalpel and the remaining layers to the sternum were opened by electrocautery. Total kilojoules of electrical energy delivered to the tissues was 9.4 +/- 5.7 for group I and 44.1 +/- 7.0 for group II (p less than 0.001). Each group was randomly divided into three subgroups (n = 6): Ia and IIa were noninoculated controls; Ib and IIb were inoculated just before skin closure; Ic and IIc were inoculated and given one preoperative dose of cefonicid. The inoculum contained Staphylococcus intermedius in a 0.5 ml suspension of 10(8) organisms. Each animal was observed and the wounds were scored daily until death or until all survivors were put to death on the eighth postoperative day. Pleural fluid was cultured at autopsy. Ten dogs died of mediastinitis (four in IIa and six in IIb), but none from group I (p less than 0.01). Positive cultures from pleural fluid in matching subgroups (n = 6) occurred as follows: one in Ia and five in IIa (p less than 0.05); one in Ib and six in IIb (p less than 0.01); zero in Ic and two in IIc. We conclude that pinpoint hemostasis on the soft tissues of the sternotomy incision significantly reduces the severity and frequency of penetrating mediastinitis.

Static strength evaluation of sacroiliac fracture-separation repairs.

The relative static strengths of seven fixation configurations for the repair of sacroiliac fracture-separations were determined. The fixation techniques were two 3.5 mm screws, one 4.5 mm screw, one 4.5 mm screw and a pin, two 4.5 mm screws, one 6.5 mm screw, one 6.5 mm screw and a pin, and two 6.5 mm screws. Each configuration was subjected to a torsional, a bending, and a shear disruptive force while the maximum load tolerated before failure was measured. Two screws were stronger than a single screw of similar size, two small screws were stronger than a single larger screw, and a reduction pin added no significant strength to a single screw repair. It was concluded that use of the largest screws possible will maximize the strength of a sacroiliac fracture-separation repair.

Pilot study on the treatment with thioproline of 24 small animals with tumors.

Thioproline (thiazolidine-4-carboxylic acid) was administered in a 16-week trial by either IM or subcutaneous routes to 23 dogs and 1 cat with solid tumors (12 animals) and incompletely excised malignant tumors (12 animals). Acute partial responses were observed in 3 of the 12 animals with solid tumors. In a mammary gland carcinoma and oral fibrosarcoma, there was tumor enlargement by the 4th day of drug therapy followed by partial regression. Drug activity appeared to be directed against tumor blood supply. Tumor progression occurred in 11 of the 12 other animals (incompletely excised tumors). Although 4 of 5 dogs with intranasal tumors were alive and relatively free of tumorous signs at 9 months or more after surgical operation was done, there was no microscopic evidence of reverse transformation or cytostatic activity in the 2 intranasal tumors that were reoperated upon. There was no hematologic or biochemical toxicosis noted. Apparent pain from injection and abscess formation were the most frequent complications from parenteral administration and would preclude using this method on a long-term basis.

Asynchronous growth of the canine radius and ulna: effects of cross pinning the radius to the ulna.

Kirschner wires were introduced into the diaphyseal region of the radius and the ulna in 4 Australian shepherd crossbred pups, and change in relationships between the bones during growth was demonstrated. The contributions to longitudinal growth of the radius from proximal and distal growth plates were also calculated. Over the period of growth, the proximal growth plate contributed approximately 40% of the length of the radius. A marked shifting of the radius in relationship with the ulna occurred. This normal shifting between radius and ulna was prevented in 6 dogs by cross pinning the radius to the ulna at 90, 111, 142, and 168 days of age. Marked change was produced in the elbow joint, where altered relationships of articular surfaces of the radius and the ulna resulted in displacement of the humeral condyle from the trochlear notch of the ulna. Changes in dogs cross pinned at 90 and 111 days of age were most severe and consisted of severe degenerative changes which were most marked on the lateral side of the distal half of the trochlear notch of the ulna.

Cryosurgical treatment of cancerous and noncancerous diseases of dogs, horses, and cats.

Cryosurgery was used to treat a variety of cancerous and noncancerous diseases in dogs, horses, and cats. Follow-up evaluation on 52 animals revealed an overall "no recurrence" rate of 61%. Among the animals with no recurrence were 12 of 17 with cutaneous lesions and 5 of 8 (horses) with sarcoids. Seven of 10 dogs with anal fistulas healed after cryosurgery, but 2 had recurrence of the disease. Treatment of invasive neoplasms of the oral and nasal cavities was not successful. Side effects and complications were minimal.

Primary hyperparathyroidism in a dog.

Anorexia, severe skeletal demineralization, and muscular weaknesss developed in a 9 year-old Collie. Hypercalcemia, hypophosphatemia, and nephrocalcinosis were found on clinical evaluation. The surgical removal of a parathyroid adenoma was followed by profound hypocalcemia that was unresponsive to calcium therapy, and the dog died. The persistent hypocalcemia was attributed to increased deposition of calcium in mineral-deficient bone.