Mild exercise expedites joint clearance and slows joint degradation in a joint instability model of osteoarthritis in male rats.

OBJECTIVE: Exercise remains a hallmark treatment for post-traumatic osteoarthritis (PTOA) and may maintain joint homeostasis in part by clearing inflammatory cytokines, cells, and particles. It remains largely unknown whether exercise-induced joint clearance can provide therapeutic relief of PTOA. In this study, we hypothesized that exercise could slow the progression of preclinical PTOA in part by enhancing knee joint clearance. DESIGN: Surgical medial meniscal transection was used to induce PTOA in 3-month-old male Lewis rats. A sham surgery was used as a control. Mild treadmill walking was introduced 3 weeks post-surgery and maintained to 6 weeks post-surgery. Gait and isometric muscle torque were measured at the study endpoint. Near-infrared imaging tracked how exercise altered lymphatic and venous knee joint clearance during discrete time points of PTOA progression. RESULTS: Exercise mitigated joint degradation associated with PTOA by preserving glycosaminoglycan content and reducing osteophyte volume (effect size (95% Confidence Interval (CI)); 1.74 (0.71-2.26)). PTOA increased hind step widths (0.57 (0.18-0.95) cm), but exercise corrected this gait dysfunction (0.54 (0.16-0.93) cm), potentially indicating pain relief. Venous, but not lymphatic, clearance was quicker 1-, 3-, and 6-weeks post-surgery compared to baseline. The mild treadmill walking protocol expedited lymphatic clearance rate in moderate PTOA (3.39 (0.20-6.59) hrs), suggesting exercise may play a critical role in restoring joint homeostasis. CONCLUSIONS: We conclude that mild exercise has the potential to slow disease progression in part by expediting joint clearance in moderate PTOA.

Synthetic hydrogels engineered to promote collecting lymphatic vessel sprouting.

The lymphatic vasculature is an essential component of the body's circulation providing a network of vessels to return fluid and proteins from the tissue space to the blood, to facilitate immune ce-ll and antigen transport to lymph nodes, and to take up dietary lipid from the intestine. The development of biomaterial-based strategies to facilitate the growth of lymphatics either for regenerative purposes or as model system to study lymphatic biology is still in its nascent stages. In particular, platforms that encourage the sprouting and formation of lymphatic networks from collecting vessels are particularly underdeveloped. Through implementation of a modular, poly(ethylene glycol) (PEG)-based hydrogel, we explored the independent contributions of matrix elasticity, degradability, and adhesive peptide presentation on sprouting of implanted segments of rat lymphatic collecting vessels. An engineered hydrogel with 680 Pa elasticity, 2.0 mM RGD adhesive peptide, and full susceptibility to protease degradability produced the highest levels of sprouting relative to other physicochemical matrix properties. This engineered hydrogel was then utilized as a scaffold to facilitate the implantation of a donor vessel that functionally grafted into the host vasculature. This hydrogel provides a promising platform for facilitating lymphangiogenesis in vivo or as a means to understand the cellular mechanisms involved in the sprout process during collecting lymphatic vessel collateralization.

Effect of Human Synovial Fluid From Osteoarthritis Patients and Healthy Individuals on Lymphatic Contractile Activity.

The lymphatic system has been proposed to play a crucial role in preventing the development and progression of osteoarthritis (OA). As OA develops and progresses, inflammatory cytokines and degradation by-products of joint tissues build up in the synovial fluid (SF) providing a feedback system to exacerbate disease. The lymphatic system plays a critical role in resolving inflammation and maintaining overall joint homeostasis; however, there is some evidence that the lymphatics can become dysfunctional during OA. We hypothesized that the functional mechanics of lymphatic vessels (LVs) draining the joint could be directly compromised due to factors within SF derived from osteoarthritis patients (OASF). Here, we utilized OASF and SF derived from healthy (non-OA) individuals (healthy SF (HSF)) to investigate potential effects of SF entering the draining lymph on migration of lymphatic endothelial cells (LECs) in vitro, and lymphatic contractile activity of rat femoral LVs (RFLVs) ex vivo. Dilutions of both OASF and HSF containing serum resulted in a similar LEC migratory response to the physiologically endothelial basal medium-treated LECs (endothelial basal medium containing serum) in vitro. Ex vivo, OASF and HSF treatments were administered within the lumen of isolated LVs under controlled pressures. OASF treatment transiently enhanced the RFLVs tonic contractions while phasic contractions were significantly reduced after 1 h of treatment and complete ceased after overnight treatment. HSF treatment on the other hand displayed a gradual decrease in lymphatic contractile activity (both tonic and phasic contractions). The observed variations after SF treatments suggest that the pump function of lymphatic vessel draining the joint could be directly compromised in OA and thus might present a new therapeutic target.

Outcomes and postoperative complications after transpelvic urethrostomy used as first-line surgery in 38 male cats with obstructive lower urinary tract disease.

OBJECTIVES: This article aimed to report on the short- and long-term outcomes after transpelvic urethrostomy (TPU) as a first-line surgery to treat obstructive lower urinary tract disease (OLUTD) in male cats. METHODS: A retrospective review and follow-up owner telephone questionnaire for cats with OLUTD undergoing TPU as a first-line surgery between 2013 and 2019, at a single referral hospital, were performed. A minimum follow-up period of 1 year was required to be included in the study. Short- and long-term complications were defined as those that occurred, respectively, within or after the first 4 weeks postoperatively. RESULTS: Thirty-eight male cats were included. The short-term complication rate was 18%. Idiopathic lower urinary tract disease (ILUTD) and stomal stenosis (SS) were the two most frequent short-term complications. Long-term complications were reported in 34% of the cats and included ILUTD, urinary tract infection and SS. The mortality rate was 5%. Eighty-two percent of the owners were satisfied with the postoperative outcome. The most common reason for owner dissatisfaction was the occurrence of SS, especially because these complications required multiple surgical revisions to be definitively managed. The long-term quality of life was considered to be good to very good by 89% of the owners. Ninety-one percent of the cats were free of clinical urinary signs at the time of the questionnaire completion. CONCLUSIONS AND RELEVANCE: TPU can be an acceptable first-line surgical technique to treat cats with OLUTD. Most cats experienced a good to very good quality of life after TPU. Most complications were transient or manageable medically. Most of the major complications were SS, which can be technically challenging to address and may require multiple revision surgeries.

Multichromatic near-infrared imaging to assess interstitial lymphatic and venous uptake in vivo.

SIGNIFICANCE: Changes in interstitial fluid clearance are implicated in many diseases. Using near-infrared (NIR) imaging with properly sized tracers could enhance our understanding of how venous and lymphatic drainage are involved in disease progression or enhance drug delivery strategies. AIM: We investigated multichromatic NIR imaging with multiple tracers to assess in vivo microvascular clearance kinetics and pathways in different tissue spaces. APPROACH: We used a chemically inert IR Dye 800CW (D800) to target venous capillaries and a purified conjugate of IR dye 680RD with 40 kDa PEG (P40D680) to target lymphatic capillaries in vivo. Optical imaging settings were validated and tuned in vitro using tissue phantoms. We investigated multichromatic NIR imaging's utility in two in vivo tissue beds: the mouse tail and rat knee joint. We then tested the ability of the approach to detect interstitial fluid perturbations due to exercise. RESULTS: In an in vitro simulated tissue environment, free dye and PEG mixture allowed for simultaneous detection without interference. In the mouse tail, co-injected NIR tracers cleared from the interstitial space via distinct routes, suggestive of lymphatic and venous uptake mechanisms. In the rat knee, we determined that exercise after injection transiently increased lymphatic drainage as measured by lower normalized intensity immediately after exercise, whereas exercise pre-injection exhibited a transient delay in clearance from the joint. CONCLUSIONS: NIR imaging enables simultaneous imaging of lymphatic and venous-mediated fluid clearance with great sensitivity and can be used to measure temporal changes in clearance rates and pathways.

Double-cut center of rotation of angulation-based leveling osteotomy for treatment of cranial cruciate ligament deficiency and excessive tibial plateau angle secondary to growth anomaly in two dogs.

CASE DESCRIPTION: A 4-year-old female Staffordshire Bull Terrier (dog 1) and a 6-year-old male Yorkshire Terrier (dog 2) were evaluated because of left pelvic limb lameness. CLINICAL FINDINGS: Both dogs had a partial rupture of the left cranial cruciate ligament associated with a unilateral excessive tibial plateau angle (51° in dog 1 and 41° in dog 2) secondary to a growth anomaly. TREATMENT AND OUTCOME: Both dogs underwent a double-cut center of rotation of angulation-based leveling osteotomy combining rotation of the proximal fragment with a cranial closing wedge ostectomy. The procedure allowed leveling of the tibial plateau to a final angle of 11° in one dog and 10° in the other without perioperative complications. Both dogs had excellent functional outcomes ≤ 4 months after the surgery. No postoperative complications were reported during follow-up (12 months and 9 months for dogs 1 and 2, respectively). CLINICAL RELEVANCE: Results for these dogs suggested that double-cut center of rotation of angulation-based leveling osteotomy can be considered as a viable treatment option for cranial cruciate ligament deficiency associated with excessive tibial plateau angle.

Outcomes of nine cats with urinary retention after sacrocaudal luxation managed with long-term urinary diversion.

OBJECTIVE: To document the outcomes of cats with urinary retention (UR) after sacrocaudal luxation (SCL) and managed with a long-term cystostomy (LTC). STUDY DESIGN: Short case series. ANIMALS: Nine client-owned cats with SCL and subsequent UR. METHODS: Nine cats suffering from non-relievable UR secondary to SCL, between March 2013 and December 2020, had a LTC placed 4.5 days post-SCL (mean, range 3.5-6.0), until clinical evidence of normal urination recovery. The bladder was emptied at least twice daily. No antimicrobial was given during LTC. Indication for tube removal was voluntary micturition with complete emptying for a minimum of three consecutive days. Recheck examinations were scheduled for post-SCL days 7 and 14, as well as for LTC tube removal. Minor and major complications and length of LTC use were recorded. RESULTS: The LTC was removed 11-42 days (mean 26 days) after placement. All cats recovered normal micturition spontaneously within 17-47 days post-SCL (mean 30.7 days): 1 cat between the 2nd and 3rd weeks, 5 cats between the 3rd and 4th weeks, and 3 cats >30 days after the trauma. Major complications, such tube dislodgement, occurred in two cats, whereas complications resolving after tube removal were recorded in 6 cats. CONCLUSION: LTC was effective at managing UR post-SCL in 9 cats. All cats recovered normal urinary function within 7 weeks. CLINICAL SIGNIFICANCE: LTC can be an alternative to manual expression or bladder catheterization in cats with temporary UR after SCL.

Use of a T'LIFT transabdominal organ retraction device in two-portal laparoscopic ovariectomy in dogs.

OBJECTIVE: To describe the use of the T'LIFT transabdominal organ retraction device to suspend ovaries during canine laparoscopic ovariectomy (LapOVE) and compare its use to a transabdominal suspension suture (TSS). DESIGN: Randomized clinical trial. ANIMALS: Client-owned intact bitches (n = 30). METHODS: Dogs were randomly assigned either to group T, in which LapOVE was performed with the T'LIFT, or to group S, in which a TSS was used. Laparoscopic ovariectomy was performed by using a standard two-portal protocol. Signalment (age, weight, body condition score [BCS], fat score of the ovarian pedicle [FSOP]), overall operative time, ovarian resection time, and perioperative complications were compared between groups. RESULTS: No significant differences were found between groups regarding age, weight, BCS, or FSOP. Surgical times were not significantly different between groups. No significant differences in major or minor complications were recorded. Overall operative time was significantly shorter for the last half of the cases compared with the first half, for the overall population, and within each group. Ovarian resection time for the last cases was significantly shorter compared with that for the first ones only in group T. CONCLUSION: The T'LIFT was used to suspend ovaries for two-portal LapOVE, with no major complications noted. There was no significant difference in surgical times or complications compared with transabdominal suturing. CLINICAL SIGNIFICANCE: The T'LIFT can be considered as an alternative to transabdominal suture for ovarian suspension in dogs undergoing LapOVE.

Endothelin-1 inhibits size dependent lymphatic clearance of PEG-based conjugates after intra-articular injection into the rat knee.

Clearance of particles from the knee is an essential mechanism to maintain healthy joint homeostasis and critical to the delivery of drugs and therapeutics. One of the limitations in developing disease modifying drugs for joint diseases, such as osteoarthritis (OA), has been poor local retention of the drugs. Enhancing drug retention within the joint has been a target of biomaterial development, however, a fundamental understanding of joint clearance pathways has not been characterized. We applied near-infrared (NIR) imaging techniques to assess size-dependent in vivo clearance mechanisms of intra-articular injected, fluorescently-labelled polyethylene glycol (PEG-NIR) conjugates. The clearance of 2 kDa PEG-NIR (τ = 171 ±â€¯11 min) was faster than 40 kDa PEG-NIR (τ = 243 ±â€¯16 min). 40 kDa PEG-NIR signal was found in lumbar lymph node while 2 kDa PEG-NIR signal was not. Thus, these two conjugates may be cleared through different pathways, i.e. lymphatics for 40 kDa PEG-NIR and venous for 2 kDa PEG-NIR. Endothelin-1 (ET-1), a potent vasoconstrictor of vessels, is elevated in synovial fluid of OA patients but, its effects on joint clearance are unknown. Intra-articular injection of ET-1 dose-dependently inhibited the clearance of both 2 kDa and 40 kDa PEG-NIR. ET-1 caused a 1.63 ±â€¯0.17-fold increase in peak fluorescence for 2 kDa PEG-NIR and a 1.85 ±â€¯0.15-fold increase for 40 kDa PEG-NIR; and ET-1 doubled their clearance time constants. The effects of ET-1 were blocked by co-injection of ET receptor antagonists, bosentan or BQ-123. These findings provide fundamental insight into retention and clearance mechanisms that should be considered in the development and delivery of drugs and biomaterial carriers for joint diseases. STATEMENT OF SIGNIFICANCE: This study demonstrates that in vivo knee clearance can be measured using NIR technology and that key factors, such as size of materials and biologics, can be investigated to define joint clearance mechanisms. Therapies targeting regulation of joint clearance may be an approach to treat joint diseases like osteoarthritis. Additionally, in vivo functional assessment of clearance may be used as diagnostics to monitor progression of joint diseases.

Radical cystectomy and subsequent ureterohysterostomy in a bitch.

OBJECTIVE: To describe and report the outcome of a ureterouterine anastomosis after unilateral dehiscence of a ureterovaginal anastomosis after total cystectomy in a bitch. STUDY DESIGN: Case report. ANIMAL: A 10-year-old intact female border collie with a urinary bladder leiomyosarcoma. METHODS: The dog was diagnosed with an invasive urinary bladder tumor, treated by radical cystectomy and bilateral ureterovaginal anastomosis. Postoperative necrosis of the distal ureter led to dehiscence of the anastomosis on the right side. To preserve the right kidney, the right ureter was anastomosed to the right uterine horn, and a stent was placed across the uterine cervix. RESULTS: The dog recovered from surgery and regained satisfactory urine output. Both ureteral anastomoses were patent at 10 months postoperatively. At 12 months postoperatively, intraluminal obstruction of the uterine stent, loss of patency of the right ureter, and severe right renal hydronephrosis were noted. The owner declined nephrectomy, and the dog died 2 months later. CONCLUSION: This is the first published report of a ureterouterine anastomosis and stenting of the uterine cervix in a dog. The functional outcome was satisfactory for 1 year postoperatively. The uterine stent and distal ureter were eventually obstructed by soft tissue. CLINICAL SIGNIFICANCE: Ureterouterine anastomosis can be considered as a salvage procedure when other surgical techniques have failed.

Control of hemorrhage through the osteotomy gap during tibial plateau leveling osteotomy: 9 cases.

OBJECTIVE: To describe a new technique to control intraoperative hemorrhage during tibial plateau leveling osteotomy (TPLO) and report subsequent short-term and long-term complications. STUDY DESIGN: Retrospective case series. ANIMALS: Nine dogs with arterial hemorrhage during TPLO. METHODS: Medical records of dogs with hemorrhage controlled through the osteotomy gap of a TPLO were reviewed at 2 institutions over 8 years. Inclusion criteria included diagnosis of single cranial cruciate ligament rupture, intraoperative arterial hemorrhage during the radial osteotomy controlled with bipolar electrocautery or hemostatic clips placed along the cranial tibial artery through the osteotomy, complete medical records, radiographic follow-up for at least 8 weeks postoperatively, and completion of long-term follow-up questionnaire by the owner. RESULTS: Dogs were 4.6 ± 1.8 years old and weighed 36.6 ± 9.7 kg. In total, 3 ± 1 hemostatic clips were placed per stifle. Intraoperative hemostasis was achieved in all cases. One of the first dogs received a blood transfusion during the procedure and had a postoperative packed cell volume of 37%. The only complication consisted of fibular fracture, which was noticed on radiographs of 1 dog 8 weeks after TPLO. CONCLUSION: Arterial hemorrhage during the radial osteotomy of a TPLO can be controlled by occlusion of the compromised artery through distraction of the osteotomy gap. This technique was not associated with long-term complications.

Video-assisted removal of metal pellet fragments from the vertebral canal following gunshot injury and long-term outcome in a cat.

OBJECTIVE:  To describe the surgical management and long-term outcome of a spinal gunshot injury in a cat. CLINICAL REPORT: A two-year-old, 4.2 kg castrated European Shorthair male cat was referred for evaluation of bilateral acute hindlimb paralysis with loss of deep pain perception in the right hindlimb associated with a perforating gunshot wound in the left side of the flank. Based on the clinical findings, the injury was localized to the fourth lumbar-first sacral spinal cord segment. The orthogonal spinal radiographs and computed tomography examination showed several metal pellet fragments within the vertebral canal of the sixth lumbar vertebra. A left mini-hemilaminectomy of the sixth lumbar vertebra pedicle combined with a mini dorsal laminectomy over the sixth to seventh lumbar vertebrae disc space were performed. A 2.4 mm 30° arthroscope was then introduced within the spinal canal to improve visibility and help with the fragment extraction. The cat was discharged from the hospital five days after surgery and the owners were encouraged to continue passive and active physiotherapy movements. RESULTS: The cat was ambulatory with a plantigrade stance eight weeks following surgery. At the last follow-up examination (24 months postoperatively), the cat was able to jump on chairs, although intermittent urinary and faecal incontinence, proprioceptive deficits, and plantigrade stance were still present. CLINICAL SIGNIFICANCE:  Decompressive surgery may promote neurological status improvement following spinal gunshot injury.

Biomechanical Comparison of Locking Compression Plate and Limited Contact Dynamic Compression Plate Combined with an Intramedullary Rod in a Canine Femoral Fracture-Gap Model.

OBJECTIVE: To compare the biomechanical properties of locking compression plate (LCP) and a limited contact dynamic compression plate combined with an intramedullary rod (LC-DCP-R) in a cadaveric, canine, femoral fracture-gap model. STUDY DESIGN: In vitro biomechanical study; nonrandomized, complete block (dog). SAMPLE POPULATION: Paired cadaveric canine femora (n = 10 dogs). METHODS: Paired femurs with a mid-diaphyseal 20 mm gap were stabilized with either LCP or LC-DCP-R. Nondestructive testing up to 60% of body weight (BW) was followed by a continuous destructive test. Comparative structural properties, 3-dimensional (3D) interfragmentary motion, and plate linear strain were evaluated. Paired comparisons were made between LCP and LC-DCP-R. RESULTS: Stiffness after nondestructive testing was significantly lower for LCP with a mean (95% confidence interval [CI]) of 61 N/mm (46-76) versus 89 N/mm (67-110) for LC-DCP-R (P = .0072). Ultimate load to failure was significantly lower for LCP with a median (interquartile range [IQR]) of 270 N (247-286) versus 371.5 (353-385) for LC-DCP-R (P = .002). Axial motion at 60% BW was significantly higher for LCP with a median (IQR) of 1.01 mm (0.71-1.26) versus 0.36 mm (0.20-0.49) for LC-DCP-R (P = .002). Shear motion was significantly higher for LCP with a median (IQR) of 1.18 (0.78-1.58) versus 0.72 mm (0.45-1.00) for LC-DCP-R (P = .018). Strain was significantly higher for mid-LCP surface with a mean (95%CI) at 60% BW of 979 µdef (579-1378) versus 583 µdef (365-801) at mid-LC-DCP-R surface (P = .0153). The elastic limit strain of the plates was not different and was reached at a mean (95%CI) load of 241 N (190-292) for LCP versus 290 N (245-336) for LC-DCP-R (P = .12). CONCLUSION: The LC-DCP-R showed higher stiffness and resistance to failure, lower interfragmentary motion, and lower plate strain and stress compared to LCP.

Evaluation of risk factors for outcome associated with adrenal gland tumors with or without invasion of the caudal vena cava and treated via adrenalectomy in dogs: 86 cases (1993-2009).

OBJECTIVE: To evaluate risk factors for outcome for dogs with adrenal gland tumors with or without invasion of the caudal vena cava treated via adrenalectomy. DESIGN: Retrospective study. ANIMALS: 86 dogs that underwent adrenalectomy for treatment of adrenal gland tumors. PROCEDURES: Medical records of dogs that underwent adrenalectomy for treatment of an adrenal gland tumor from 1993 to 2009 were reviewed; data collected including signalment, clinical signs, diagnostic test findings, treatments prior to surgery, findings at surgery including additional procedures performed and extent of caudal vena caval invasion (local invasion [caudal to the hepatic portion of the vena cava] or extensive invasion [cranial to the hepatic portion of the vena cava]), procedures performed during surgery, histopathologic diagnosis, perioperative complications, follow-up data, and necropsy findings. RESULTS: Of the 86 dogs, 14 had adenomas, 45 had adrenocortical carcinomas, and 27 had pheochromocytomas. Fourteen dogs had invasion of the caudal vena cava; of these tumors, 7 were locally invasive and 7 were extensively invasive. Risk factors for poor short-term survival (death within 14 days following surgery) were vena caval invasion, extent of invasion, pheochromocytoma, intraoperative transfusion, and postoperative factors including disseminated intravascular coagulation, pancreatitis, hypotension, hypoxemia, and renal failure. Multivariate analysis of risk factors for poor short-term survival revealed that extensive invasion was the most important factor. Regardless of extent of invasion or tumor type, long-term survival was possible. CONCLUSIONS AND CLINICAL RELEVANCE: Invasion of the caudal vena cava, particularly tumor thrombus extension beyond the hepatic hilus, was associated with a higher postoperative mortality rate, but did not affect long-term prognosis in dogs undergoing adrenalectomy because of an adrenal gland tumor.

Monotonic aspects of the mechanical behaviour of bottom ash from municipal solid waste incineration and its potential use for road construction.

Municipal solid waste incineration (MSWI) bottom ash is an atypical granular material because it may include industrial by-products that result from the incineration of domestic waste. The prospects for the beneficial use of this particular material mainly lie in the field of road construction, as a substitute for the traditional natural aggregates. However, its mechanical properties are still little known, particularly in term of stiffness and deformability, characteristics that are essential to the construction of a durable roadway. The purpose of this paper is to describe better the mechanical behaviour of this recycled material. In order to reach this objective, a large experimental campaign is presented. The first part of this paper presents and comments in detail on the results obtained from static monotonic tests. Oedometric and triaxial shear tests were performed on MSWI bottom ash both before and after treatment with a specific hydraulic binder. These tests allow specification of the mechanical characteristics of the MSWI bottom ash, such as the initial Young's modulus, Poisson's ratio, the compressibility index, the friction angle, and the contracting or dilating behaviour of the material. The results reveal a mechanical behaviour similar to that of initially dense standard materials (sands, unbound granular materials) and a dependence on the applied average pressure, characteristic of the mechanical behaviour of granular media. More laboratory data on other samples of MSWI bottom ash are required to ensure that this comparison is statistically valid.

Hemodynamic effects of interpleural lidocaine and bupivacaine combination in anesthetized dogs with and without an open pericardium.

OBJECTIVE: To identify dysrhythmias and hemodynamic changes after lidocaine and bupivacaine infusion into the interpleural space with an open pericardium. STUDY DESIGN: Experimental study. ANIMALS: Six adult dogs. METHODS: Systemic arterial pressure and electrocardiogram were recorded. A 7.5 Fr Swan-Ganz catheter was advanced to the level of the main pulmonary artery to record pulmonary arterial pressure. Cardiac output was measured by a thermodilution technique. A pericardial window (PW) was performed in 3 dogs using thoracoscopy. Hemodynamic variables were recorded before and 15 minutes after injection of lidocaine (1.5 mg/kg) and bupivacaine (1.5 mg/kg) into the pleural space in the control group and in the pericardial space for the PW group. A randomized-block ANOVA for repeated measures was used to evaluate the effect of local anesthetic administration on hemodynamic and electrophysiologic variables in dogs with a pericardectomy. RESULTS: Each dog maintained sinus rhythm. Infusion of local anesthetic induced a significant increase in right ventricular diastolic pressure (P = .002) and a significant decrease in stroke volume (P = .047) in both groups; however, the effects were not significantly different between groups. CONCLUSIONS: Infusion of lidocaine and bupivacaine, either intrapleural or in the pericardial space, had a mild detrimental effect on cardiac output. CLINICAL RELEVANCE: Intrapleural administration of lidocaine and bupivacaine at a therapeutic dose can be used safely in healthy dogs with a pericardectomy.