Long-term radiographic appearance of a bioabsorbable biocomposite tibial tuberosity advancement cage implant.

OBJECTIVE: To report the radiographic appearance of a bioabsorbable biocomposite tibial tuberosity advancement cage at least 1 year after implantation. Design Retrospective case series. METHODS: Medical records (February 2014-March 2015) of dogs receiving a biocomposite tibial tuberosity advancement cage were reviewed. Cases were selected if they had undergone surgery at least 1 year before the selection, no additional surgeries were performed, and no known surgical site infection had occurred. Medical record information assessed included signalment, body weight (kg), affected stifle joint (left or right), date of original surgery and the size of biocomposite cage used (9 or 12 mm). Radiographs were evaluated by two blinded radiologists who calculated percentages of osteolucency present in five zones around the cage and assigned a numerical score based on these calculations. Variables were evaluated statistically for effect on lucency percentage and numerical score. RESULTS: Fifty dogs were included. Zone 5 (caudoproximal area) was found to have the lowest lucency percentage and score and zone 3 (distal area) had the highest lucency percentage and score. Twelve-millimetre cages were significantly associated with a higher lucency numerical score than 9 mm cages. CONCLUSION: A biocomposite tibial tuberosity advancement cage was found to have variable amounts of radiographically apparent osseous integration at least 1 year after implantation.

The effect of screw angulation and insertion torque on the push-out strength of polyaxial locking screws and the single cycle to failure in bending of polyaxial locking plates.

OBJECTIVE: To evaluate the mechanical properties of the Polyaxial Advanced Locking System (PAX) in screw push-out and four-point bending. MATERIALS AND METHODS: Screw push-out: PAX locking screws were applied to first generation PAX plates at three different insertion angles with two different insertion torques. A load was applied parallel to the screw axis, and screw push-out force was measured. Four-point bending: PAX plates were applied to a bone model and a fracture gap was simulated. Bending stiffness, bending strength, and bending structural stiffness were evaluated and compared to published data. RESULTS: Screw push-out forces were significantly higher at 0 and 5 degree insertion angles when compared with an insertion angle of 10 degrees. An insertion torque of 3.5 Nm also produced significantly higher push-out forces compared to 2.5 Nm. Four-point bending: Qualitative comparison of the data gained in this study with previously published data suggests that the PAX system bending stiffness and bending structural stiffness seems to be higher than that of other veterinary orthopaedic implants, but the bending strength was similar. CLINICAL RELEVANCE: The PAX locking system offers the benefit of polyaxial screw insertion while maintaining comparable biomechanical properties to other currently available orthopaedic implants.

In vitro mechanical evaluation and comparison of two crimping devices for securing monofilament nylon and multifilament polyethylene for use in extracapsular stabilization of the canine stifle.

OBJECTIVE: To compare the tensile strength and stiffness of non-absorbable suture loops created with two types of crimping devices. METHODS: Loops of monofilament nylon leader line (MN) of 18 kg, 36 kg, and 45 kg multifilament polyethylene (MP) with a crimp and MP with a crimp and knot were mechanically tested to failure in quasistatic tensile loading after being created with either a wave pattern crimp device or three applications of a single crimp device. Each testing group consisted of five samples. Tensile loading to failure at a rate of 9.5 mm/s was used. Failure was defined as a sudden drop in the recorded force. RESULTS: All suture materials failed by breaking near the crimp tube with both crimp devices, with exception of the MP without knot, which slipped through the crimp tube using both devices. Sutures secured with the wave pattern crimping device were significantly stronger with a higher load yield, maximum load, displacement yield, failure displacement, and maximum displacement than the single crimp device. Loops of MP suture crimped by either device plus the addition of a surgeon's knot resulted in a significantly stronger construct than unknotted crimped MP constructs. Crimped MP combined with knot were significantly stiffer, but not stronger, than crimped 45 kg MN. CLINICAL SIGNIFICANCE: Performing extra- capsular repair for ruptured cranial cruciate ligaments with the wave pattern crimp system may result in lower failure rates due to the construct being significantly stronger than the single crimp system.

Pharmacokinetics of an immediate and extended release oral morphine formulation utilizing the spheroidal oral drug absorption system in dogs.

This study investigated the pharmacokinetics of a human-labeled oral morphine formulation consisting of both immediate and extended release components in dogs. In a randomized design, 14 dogs were administered either 1 or 2 mg/kg morphine orally. Blood samples were collected up to 24 h post drug administration. Plasma concentrations of morphine were measured using high-pressure liquid chromatography with electrochemical coulometric detection. For both groups, maximal concentration occurred at 3 h post drug administration followed by a gradual decrease in morphine concentration over 24 h. There was substantial variability in morphine concentrations among dogs. The higher dose group produced a greater exposure (higher area-under-the-curve), higher peak concentration, longer half-life and a shorter time to peak concentration (t(max)). The specific oral morphine formulation used in this study produced sustained plasma morphine concentrations over 24 h compared with previous intravenous dosing and immediate-release oral morphine studies. However, the low morphine plasma concentrations and high variability produced from this formulation, suggest that the clinical application of this formulation at the doses evaluated in this study are limited.

Outcome and prognostic factors in non-ambulatory Hansen Type I intervertebral disc extrusions: 308 cases.

Thoracolumbar intervertebral disc disease is the most common cause of caudal paresis in dogs. Whilst the pathogenesis of the extrusion has been widely studied, treatment protocols and prognostic factors relating to outcome remain controversial. Recent studies have examined a multitude of factors relating to time to regain ambulation after decompressive surgery. Most intervertebral disc herniations occur in the thoracolumbar region, causing upper motor neuron signs in the rear limbs, which are thought to have a more favourable prognosis compared to the lower motor neuron signs created by herniation of an intervertebral disc in the caudal lumbar region. Due to the potential disruption of the lumbar intumescence, lower motor neuron signs have been reported as having a less favourable prognosis. The purpose of this study was to evaluate the intervertebral disc space as a prognostic factor relating to ambulatory outcome and time to ambulation after decompressive surgery. Hansen Type I intervertebral disc extrusions were studied in 308 non-ambulatory dogs. Preoperative and postoperative neurological status, corticosteroid use, signalment, intervertebral disc space, postoperative physical rehabilitation, previous hemilaminectomy surgery, disc fenestration, return to ambulation, and time to ambulation were reviewed.

Pharmacokinetics, pharmacodynamics, and analgesic effects of morphine after rectal, intramuscular, and intravenous administration in dogs.

OBJECTIVE: To compare systemic bioavailability and duration for therapeutic plasma concentrations and cardiovascular, respiratory, and analgesic effects of morphine administered per rectum, compared with IV and IM administration in dogs. ANIMALS: 6 healthy Beagles. PROCEDURE: In a randomized study, each dog received the following: morphine IV (0.5 mg/kg of body weight), morphine per rectum (1, 2, and 5 mg/kg as a suppository and 2 mg/kg as a solution), and a control treatment. Intramuscular administration of morphine (1 mg/kg) was evaluated separately. Heart and respiratory rates, systolic, diastolic, and mean blood pressures, adverse effects, and plasma morphine concentrations were measured. Analgesia was defined as an increase in response threshold, compared with baseline values, to applications of noxious mechanical (pressure) and thermal (heat) stimuli. Data were evaluated, using Friedman repeated-measures ANOVA on ranks and Student-Newman-Keuls post-hoc t-tests. RESULTS: Significant differences were not found in cardiovascular, respiratory, or analgesia values between control and morphine groups. Overall systemic bioavailability of morphine administered per rectum was 19.6%. Plasma morphine concentration after administration of the highest dose (5 mg/kg) as a suppository was significantly higher than concentrations 60 and 360 minutes after IV and IM administration, respectively. A single route of administration did not consistently fulfill our criteria for providing analgesia. CONCLUSIONS AND CLINICAL RELEVANCE: Rectal administration of morphine did not increase bioavailability above that reported for oral administration of morphine in dogs. Low bioavailability and plasma concentrations limit the clinical usefulness of morphine administered per rectum in dogs.

Incomplete urethral duplication with cyst formation in a dog.

Incomplete urethral duplication with cyst formation was diagnosed in a dog that had soft, fluctuant, subcutaneous swellings in the ventral perineal and penile areas and a history of nocturia and incontinence during recumbency that were unresponsive to treatment with antibiotics. Retrograde urethrocystography, voiding urethrography, double-contrast cystography, radiography after direct administration of contrast medium into cystic structures, and excretory urography were performed to evaluate the urinary tract. Communication between the cysts and the urethra was demonstrated radiographically only after intralesional injection of contrast medium. Nocturia and incontinence resolved after surgical removal of the urethral duplication and cysts. The dog was clinically normal 1 year after surgery.

Pericolonic mass containing chyle as a presumed sequela to chronic pancreatitis in a dog.

A 9-year-old dog was admitted because of recurrent episodes of chronic pancreatitis. Ultrasonography revealed a multiloculated, fluid-filled cystic mass at the caudal portion of the stomach. Guided fine-needle aspirates yielded a fluid consistent with chyle. The dog underwent surgery during which a 6- to 8-cm mass was found adhered to the mesocolon and serosa of the transverse colon. Intraoperative lymphangiography revealed lymphangiectasia, but contrast medium did not accumulate within the mass. The mass and a portion of transverse colon were removed en bloc. Results of histologic examination were consistent with an abscess. Pancreatic enzymatic digestion may allow abscesses to extend beyond pancreatic parenchyma, cause severe local inflammation, and encapsulate and incorporate adjacent abdominal lymphatics. Subsequent lymphatic leakage can result in chyle within the abscess. Inflammatory masses of the pancreas are a rare, but serious, complication of pancreatitis in dogs. Familiarity with these types of lesions can aid in selection of appropriate treatments.

Pleural effusion as a complication of extrahepatic biliary tract rupture in a dog.

Bile pleural effusion associated with traumatic rupture of the extrahepatic biliary tract and bile peritonitis in a dog is described. Pleural and abdominal fluids were identical cytologically and chemically despite a grossly intact diaphragm. Transfer of peritoneal fluid across the diaphragm via lymphatics and subsequent leakage into the pleural space is the likely cause of effusion. Pleural and abdominal fluid accumulation resolved spontaneously with repeated abdominocenteses and supportive care.