Evaluation of the polypropylene braid as a prosthetic anterior cruciate ligament replacement in the dog.

The purpose of this scientific investigation, made prior to 1977, was to determine the suitability of a polypropylene prosthetic ACL. The 3.6 mm diamond-braided prosthesis was implanted in 17 dogs. The device was passed through a trough on the anteromedial side of the tibial crest and over the top of the lateral femoral condyle. The device was internally fixed at both ends to bone using a bushing-lag screw technique which resulted in solid prosthesis immobilization at the time of surgery. Animals were necropsied at 3, 6, or 10 months after implantation. There was partial or total disruption of the prosthesis in all cases. Destruction of the prosthesis was attributed to excessive viscoelasticity of the device and fatigue failure. Based on this study, prosthetic ACL replacement using this device is not recommended.

Portacaval shunt as treatment for hypercholesterolemia. Metabolic and morphological effects in a swine model.

Since 1973 the portacaval shunt has been used as a treatment for homozygous familial hypercholesterolemia. Favorable results have been reported, but the mechanism or reduction of cholesterol is not clear. The objective of this research was to evaluate mechanisms of lipid alterations after portacaval shunting in Yucatan miniature swine. The animals were fed a high-fat diet, similar in composition to the average American diet, with or without added cholesterol. Controls were fed the atherogenic diet (+ cholesterol) for 8 months. Pigs were fed atherogenic or American diets for 8 months, then surgery (shunt or sham) was performed. They were continued on the diets for another 8 months. The vascular system was examined for the distribution and severity of atherosclerotic disease. Blood lipids and numerous biochemical indices were measured. Progression of atherosclerosis was slowed by portacaval shunting. Low density lipoprotein (LDL) concentrations were positively and high density lipoprotein (HDL) concentrations were negatively correlated with severity of atherosclerosis. Serum insulin concentrations were positively correlated with atherosclerosis. Cholesterol synthesis was increased by the shunting and decreased by cholesterol feeding. The cholesterol-fed swine is not an adequate model for familial hypercholesterolemia, but the results are consistent with inhibition of the atherosclerotic process and the involvement of lipoproteins and insulin in the mechanisms.

Analgesic effects of butorphanol in horses: dose-response studies.

The analgesic effects of butorphanol (0.05, 0.1, 0.2, and 0.4 mg/kg), pentazocine (2.2 mg/kg), and butorphanol vehicle (0.04 ml/kg) were observed in 6 horses. These horses were instrumented to measure response objectively to painful superficial and visceral stimuli. The tested drugs were given IV according to a Latin square design. After preinjection base-line measurements were made, the analgesic effects were observed at 15 and 30 minutes and then at 30-minute intervals until postinjection minute 240. Analgesic effects of butorphanol were dose-related, with durations between 15 and 90 minutes. Duration of analgesia after pentazocine (2.2 mg/kg) was given was between 15 and 30 minutes. When compared with pentazocine, the 0.4 mg/kg dose of butorphanol provided a more intense and longer period of analgesia. A butorphanol dose of 0.2 mg/kg IV appears optimal. On a dose-body weight basis, the potency of butorphanol was 10 to 17 times that of pentazocine. Behavioral side effects were noted with both agents and were dose-related.

Effects of butorphanol, flunixin, levorphanol, morphine, and xylazine in ponies.

The analgesic and behavioral effects of butorphanol (0.22 mg/kg), flunixin (2.2 mg/kg), levorphanol (0.033 mg/kg), morphine (0.66 mg/kg), and xylazine (2.2 mg/kg), given IM were observed in 8 ponies. These ponies were instrumented to measure response objectively to painful superficial and visceral stimuli. Effects on the cardiopulmonary system and rectal temperature also were evaluated in 6 of these ponies. Observations were conducted before drug injection (base-line values) and after injection at 30, 60, 120, 180, and 240 minutes. Xylazine provided the highest pain threshold for the first 60 minutes and a sedative effect for 105 minutes. The effects for superficial pain and visceral pain persisted 3 hours and 4 hours, respectively. Morphine produced good analgesia for superficial pain (30 minutes), whereas butorphanol provided good effect for visceral pain (4 hours). A slight degree of analgesia for visceral pain was obtained after morphine (1 hour) and levorphanol (4 hours); flunixin did not induce analgesia. Butorphanol, levorphanol, and morphine stimulated motor activity. Behavioral effects did not occur after flunixin was given. Xylazine decreased systolic, diastolic, and mean blood pressures. Marked increases in these pressures, heart rate, and respiratory rate were observed after morphine was given. Changes of central venous pressure, rectal temperature, and blood gas values remained within base-line limits after both drugs were given. Butorphanol increased heart rates for 1 hour; flunixin and levorphanol did not alter any of the above values.

Piretanide (HOE 118) in dogs.

Piretanide, a "loop" diuretic, was administered orally and IV at 3 dose levels to healthy Beagles. The effects were measured over an 8-hour period. A marked diuresis occurred with both methods of administration at all dose levels. It was characterized by increased excretion of Na+, Cl-, and, to a lesser extent, K+. Urine osmolality and specific gravity decreased significantly, while urine Na+ and K+ concentrations decreased concurrently. Changes from base lines were not detected in hematologic values, except for serum K+ which reached below base line with larger doses. Piretanide is a potent diuretic and treated patients should be monitored for hypokalemia.

Pneumatically powered vertebral displacement device for dogs.

A pneumatically powered trauma device was developed to produce vertebral displacement and spinal cord injury in dogs. After surgical exposure of the spine, displacement was done without laminectomy or cutting of the intervertebral disc. Trauma resulted in luxation between L1 and L2 or fractures of L1 and L2. Force required to cause displacement was recorded via a load sensing system and ranged between 1,848 and 2,666 newtons. In a few dogs, there was partial return of the displaced segment upon pressure release from the device at posttrauma hour 4. The device was an effective means of producing spinal injuries in dogs, and provides a method for studying spinal column and spinal cord injuries.

A method for quantitation of hepatic, pancreatic, and intestinal function in conscious Yucatan miniature swine.

A right laparotomy was performed in anesthetized miniature swine. A hepatic vein was catheterized through the diaphragmatic surface of the left lateral lobe of the liver or through the cut surface of the right lateral lobe following a partial lobectomy. Continuous wave Doppler flow cuffs were applied to the hepatic artery and portal vein. Portal vein catheterization was accomplished through a stab incision made through the center of a preplaced purse string suture. Catheters and flow cuff wires exited the abdomen at the dorsal limit of the incision and were placed in nylon packs. Sterile surgery of the right ventro-lateral cervical region allowed catheterization of the right external jugular vein and carotid artery. These catheters were passed subcutaneously to the dorsum of the neck and inserted into another nylon pack. This method allowed repetitive experiments on conscious miniature swine after recovery from surgery. It allowed accurate quantitative determination of hepatic extraction of hormones as well as extraction of production of metabolites. Rates of intestinal absorption and pancreatic hormone secretion also could be assessed.

Combined pharmacologic and surgical treatments for acute spinal cord trauma.

Acute spinal cord trauma was induced by the Allen method at T12 in 48 dogs. Six groups of 7 dogs each were treated with combinations of pharmacologic and surgical treatments; a 7th group of 6 dogs remained as traumatized nontreated controls. Results indicate an additive therapeutic effect in those patients treated with myelotomy and dimethyl sulfoxide. Dexamethasone, reserpine, and perfusion with hypertonic dextrose solution were of no benefit.

Tissue reaction to suture materials in infected surgical wounds--a histopathologic evaluation.

Suture materials are foreign bodies which induce and prolong tissue reaction in the wound area. Cellular responses to infected wounds containing 7 suture materials (braided polyglycolic acid [BPGA, Dexon], multifilament stainless steel, monofilament nylon, black braided silk, braided Dacron [Mersilene], and plain and chromic catgut) were studied at 6, 10, 20, and 40 days. Cellular reaction varied with different suture materials. In general, neutrophils were the predominant cells in acute infection, but later, macrophages and fibroblasts predominated. Occasionally, plasma cells, lymphocytes, eosinophils, and giant cells were present. In the infected wounds with implants of plain catgut, chromic catgut, silk, and braided Dacron, there were large numbers of neutrophils even in chronic implantation, indicating persistence of local infection. With nylon, steel, and BPGA, the number of neutrophils rapidly decreased. Although BPGA induced intense acute reaction, the response was mild in chronic implantation. It appeared to be absorbed more slowly than plain or chromic catgut, and tissue reaction was minimal in the absorption stages. A reaction similar to the Splendore-Hoeppli phenomenon was seen around multifilament silk strands in chronic stages of implantation.

Further studies with polyglycolic acid (Dexon) and other sutures in infected experimental wounds.

Seven suture materials (braided polyglycolic acid [BPGA, Dexon], multifilament stainless steel, monofilament nylon, black braided silk, braided Dacron (BD, Mersilene], and plain and chromic catgut) were implanted in surgical wounds which were inoculated with 3 dilutions of Staphylococcus aureus. The degree of swelling was measured at 6, 10, 20, and 40 days. Monofilament nylon and multifilament steel produced the least amount of swelling; plain and chromic catgut produced the most. The BPGA, BD, and silk caused swellings that were intermediate in degree. In chronic implantations, inflammatory reactions to the various suture materials differed from those occurring soon after implantation. Response to steel and nylon remained minimal; that to silk was gradual, but overall became the most severe. There was slightly less response with BD. The catguts varied little from each other in their responses. Intense reaction was induced by BPGA in the early stages, but the response was mild in chronic implantations.

Objective tests of analgesic drugs in ponies.

An equine model, subjected to three kinds of pain (superficial, deep, and visceral) was used to test effects of analgesic drugs. Two groups of ponies were used. In the first group of six ponies, six drugs (fentanyl, meperidine, methadone, oxymorphone, pentazocine, and xylazine) were given according to a Latin square experimental design, and tests were made at 30-minute intervals for 4 hours. Mean values (control) for the three kinds of pain were obtained before and after the tests and were compared with the mean values (drugs) obtained over 2- and 4-hour intervals (four and eight measurements per interval, respectively). Xylazine was significantly more effective in obtunding deep pain (P less than 0.05) at 2- and 4-hour intervals than were the other drugs. Significant differences were not found between values for controls and values for drugs tested for relief of superficial and visceral pain at 2- and 4-hour intervals. In the second group of four ponies, the drug (xylazine) determined most effective in group 1 ponies was given alone or in combination with the next most effective drugs (fentanyl, meperidine, and oxymorphone). Data were obtained in the same manner as for the first group. Mean values were calculated for 2- and 4-hour intervals, and the variance was analyzed. Xylazine and fentanyl combined had the best 2- and 4-hour performance for the relief of visceral pain in the second group (P less than 0.1). Neither xylazine nor a combination of drugs differed markedly from control values for 2- and 4-hour intervals for relief of superficial and deep pain.

Evaluation of gamma radiation therapy in experimentally induced hemorrhagic pancreatitis in dogs.

Acute bile-trypsin pancreatitis was induced in two groups of six dogs each. One group was given supportive treatment only; the second group was treated with irradiation of the pancreas (400 rad). A third group of six dogs was irradiated, but pancreatitis was not induced. A 13-fold increase in survival time was observed in the dogs with pancreatitis which had been irradiated. Irradiation alone was found to reduce the volume of pancreatic secretion with a relative increase in trypsin content. Modification of the inflammatory reaction by irradiation and reduction in pancreatic secretion probably account for the therapeutic effect.

Lumbar spondylectomy in the subhuman primate.

Removal of the 2nd or 3rd lumbar vertebrae (or both) has been accomplished in the subhuman primate (Macaca mulatta). Variations between this animal and the dog in posture, vertebral column anatomy, and spinal cord blood supply made no apparent difference in the results when compared with those in previous experiments. All macaques were able to clinb and to use their hind legs in a normal manner within 3 days after surgical operation. Once hair had regrown over the surgical incision, persons not familiar with the animals were not able to identify the animals that had undergone surgical operation. If a single vertebra was removed, use of spinous process and a single vertebral body plate was sufficient to stabilize the vertebral column. Except for 1 rhesus macaque whose spinous process plates were removed 20 days after the operation, vertebral columns of macaques (n = 3) that underwent single spondylectomy healed in nearly normal alignment. With the removal of 2 lumbar vertebrae, the previously described stabilization procedure was not sufficient to prevent kyphotic deformity of the vertebral column. Spinous process plates from 1 macaque were removed after 64 days. However, all these macaques (n = 3) could climb and use their legs as well as others in the colony.

Plating of canine scapular fractures.

The purpose in this study was to determine whether there was a significance difference between conservative management and plating of scapular body fractures. Bilateral scapular body fractures were created in 10 dogs. The left scapula in each dog was treated by open reduction and plating of the scapular spine. The right scapula was not treated. Plating enhanced healing and early return of function, but there was no significant difference in the long-term results.

Evaluation of polytetrafluoroethylene-graphite-coated total hip prostheses in goats.

This study was designed to determine if a porous polytetrafluoroethylene-graphite coating could furnish long-term stabilization of total hip prostheses. Prostheses were surgically implanted in 12 mature goats, which were observed postoperatively for as long as 1 year. Effective stabilization occurred in only 4 animals. Poor results in the other animals were attributed to lack of stabilization of the prostheses following initial implantation, which allowed movement at the interface between bone and polytetrafluoroethylene-graphite.