Open Heart Surgery with Deep Hypothermia and Cardiopulmonary Bypass in Small and Toy Dogs

Objective: To evaluate open heart surgery with deep surface‐induced hypothermia (sHT) and low‐flow cardiopulmonary bypass (CPB) in small and toy‐breed dogs. Study Design: Case series. Animals: Small breed dogs (n=8) weighing <5.5 kg with naturally occurring cardiac disease. Methods: Deep sHT under isoflurane anesthesia and low‐flow rate CPB with a small‐volume prime circuit were used. Ventricular septal defect was closed directly in 2 dogs and severe mitral regurgitation was corrected with mitral valvuloplasty (MVP) in 5 dogs and mitral valve replacement in 1 dog. Results: All dogs survived surgery; 1 dog died 6 days and 1 died 2 months after MVP. The other 6 dogs lived (mean follow‐up, 32.8 months; range, 12–65 months). Mean body weight at surgery was 3.6 kg (range, 2–5.3 kg). Mean lowest esophageal temperature was 21.4°C (range, 19.8–23.8°C). Mean lowest pump flow volume was 29.2 mL/kg/min (range, 9.4–57.7 mL/kg/min) during aortic cross‐clamping (mean, 53.5 minutes; range, 25–79 minutes). Mean hematocrit before CPB was 38.6% (range, 33–47%) and 20.3% (range, 13–24%) during CPB with a small circuit priming volume of 225–260 mL. Conclusion: Deep sHT with low‐flow rate CPB may be used for open heart surgery in small dogs weighing <5.5 kg. Clinical Relevance: Open heart surgery for selected congenital defects and acquired defects in small and toy‐breed dogs may be successfully performed using deep sHT and CPB.     

Technique and postoperative management for successful cardiopulmonary bypass and open-heart surgery in dogs

Twenty-six healthy mixed-breed dogs (25 to 35 kg) underwent hypothermic (27 C) cardiopulmonary bypass. The heart was arrested with cold (4 C) cardioplegic solution, and left ventriculostomy performed. Postoperative mortality was 11.5% (3/26). Two deaths were attributable to ventricular fibrillation the night after surgery, and one death 2 weeks later was the result of pulmonary embolization. All other dogs recovered promptly and were well at follow-up evaluation 6 weeks later. The most important considerations were (1) the surgical approach, ie, combining left lateral thoracotomy with cannulation of the right atrium and left femoral artery for cardiopulmonary bypass (CPB) (avoiding median sternotomy and aortic arch perfusion), (2) the adherence to strict criteria for CPB perfusion, consisting of blood flow of at least 2.2 L/m2/min, PCV no less than 25%, gas flow through the oxygenator (97% O2, 3% CO2) of at least 3.5 L/min, maintenance of a mean arterial blood pressure greater than 60 mm of Hg, and heparinization to maintain activated clotting time over 480 seconds, (3) the use of dipyridamole infusion to preserve platelets during CPB, resulting in decreased postoperative blood loss and (4) the monitoring of cardiac, respiratory, renal, and neurologic functions before, during, and after the operation, with particular emphasis on fluid balance and electrolytes. We concluded that a high success rate is possible for open-heart surgery in the dog requiring cardiopulmonary bypass, but only through meticulous surgical technique and the combined application of many monitoring techniques, with timely intervention to correct serious departures from homeostasis.     

A comparative study between hypothermic and normothermic cardiopulmonary bypass in open heart surgery in dogs--effects on systemic hemodynamics.

Open heart surgery was performed on two groups of dogs under extracorporeal circulation with or without hypothermia to investigate hemodynamic changes during extracorporeal circulation. During hypothermic cardiopulmonary bypass (CPB), arterial O2 tension and postoperative blood pressure were favorably maintained, indicating that hypothermic extracorporeal circulation can be performed for a long period of time. On the other hand, during normothermic CPB, the average surgical duration was significantly shorter, and marked shifts in the concentrations of various enzymes were suppressed. However, due to reductions in arterial O2 tension, the length of cardiac arrest time was restricted, demonstrating that this method is suitable for performing extracorporeal circulation for CPB of relatively short duration. If circulation circuitry can be improved, such as through the development of a surpassing oxygenator, normothermic CPB would incur less stress on the body, thus making it preferential to hypothermic CPB in most cases.     

GP IIb-IIIa Receptor Blockers Minimize Vascular and Perivascular Damage in the Hippocampus after Cardiopulmonary Bypass Management

Brain injury remains a significant and potentially devastating outcome of cardiopulmonary bypass (CPB) under circulatory arrest. These outcomes caused by a microvasculature embolization are associated with increased mortality, longer hospital stays and increased use of intermediate or long term care facilities. The administration of heparin in heart surgery during deep hypothermic cardiopulmonary bypass is the basic prophylactic strategy for reducing or even preventing, microvasculature embolization. Unfortunately, an incidence of neuropsychological impairments (NPI) is found in as many as 25 % of the survivors. As it is suspected that these impairments are correlated with morphological alterations, in our study we use the GP IIb-IIIa receptor blocker Eptifibatide for the inhibition of platelet aggregation, in order to look for a reduction of tissue damage compared to the standard treatment. Two groups of 11 piglets (mean body weight of 15±5 kg) underwent 10-minute normothermic bypass, 40-minute cooling on cardiopulmonary bypass, 60-minutes deep hypothermic circulatory arrest (DHCA) at 15°C, and 40-minute rewarming to 37°C. Group 1 was treated only with unfractionated heparin (UFH), whereas Group 2 was medicated with Eptifibatide, in addition to the UFH-treatment group 1. After rewarming, all animals underwent bilateral carotid perfusion with 4% paraformaldehyde. Histological investigations of semi thin sections reveal a marked decrease of hippocampal alterations by using the GP IIb-IIIa receptor blocker in addition to standard UFH treatment. We detect a reduction of degenerative areas in perivascular (vessels with 10–30 μm in diameter) tissue. These semi-quantitative data are confirmed by ultrastructural findings.     

Limb Salvage Surgery for Osteosarcoma of the Proximal Humerus: Outcome in 17 Dogs

Objective —To describe function and identify factors that affect outcome in dogs undergoing limb salvage surgery for osteosarcoma (OS) of the proximal humerus.
Study Design —A retrospective study of dogs in which OS of the proximal humerus was treated with limb salvage surgery.
Animals —17 client-owned dogs.
Methods: Records were analyzed for functional outcome, recurrence, metastasis, and survival.
Results —Outcome was good to excellent in 12% of dogs. Recurrence, metastasis, and survival were significantly affected by completeness of surgical margins. Double plating of the distal allograft-host junction significantly reduced frequency of biomechanical failure.
Conclusions —Limb salvage surgery for OS of the proximal humerus did not result in acceptable function and was fraught with postoperative complications. Outcome was significantly affected by completeness of surgical margins.
Clinical Relevance —Limb salvage surgery for OS of the proximal humerus in dogs cannot be recommended until improvement in functional outcome and reduction in postoperative complications can be achieved. The dependence of outcome on completeness of surgical margins supports aggressive en bloc resection and marking and evaluating surgical margins.     

Congenital Interruption of the Portal Vein and Caudal Vena Cava in Dogs: Six Case Reports and a Review of the Literature

Objective —To describe six dogs with congenital abnormalities involving the portal vein, caudal vena cava, or both.
Animals —Six client-owned dogs with congenital interruption of the portal vein or the caudal vena cava, or both.
Methods —Portal vein and caudal vena cava anatomy was evaluated by contrast radiography and visualization at surgery. Vascular casts or plastinated specimens were obtained in three animals.
Results —Portal blood shunted into the caudal vena cava in four dogs and the left hepatic vein in one. Two of these five dogs also had interruption of the caudal vena cava with continuation as azygous vein, as did an additional dog, in which the portal vein was normally formed. Portal vein interruption was present in 5 of 74 (6.8%) dogs with congenital portosystemic shunts evaluated at the Veterinary Teaching Hospital during the study period.
Conclusions —Serious malformations of the abdominal veins were present in more than 1 in 20 dogs with single congenital portosystemic shunts.
Clinical Relevance —Veterinarians involved in diagnosis and surgery for portosystemic shunts should be aware of these potential malformations, and portal vein continuity should be evaluated in all dogs before attempting shunt attenuation.     

Application of Ventral Pins and Polymethylmethacrylate for the Management of Atlantoaxial Instability: Results in Nine Dogs

Objective — The purpose of this report was to determine the efficacy of the application of ventral pins and polymethylmethacrylate for the management of congenital and traumatic atlantoaxial instability (AAI) in dogs.
Study Design — Medical records and radiographs of nine dogs with AAI were reviewed for neurological deficits, clinical diagnosis, surgical technique, and long-term outcome.
Sample Population — Six toy breed dogs with congenital AAI and three medium or large breed dogs with traumatic AAI were identified for inclusion in the study.
Methods — The atlantoaxial joints of nine dogs with AAI were surgically stabilized using ventral application of pins and polymethylmethacrylate. Follow-up evaluation for resolution of clinical signs and possible complications of surgery was performed in all dogs. The median follow-up time for surviving dogs (8) was 11.5 months with a mean of 13 months.
Results — An excellent outcome was identified in five patients. Three dogs had a good outcome and one dog died of respiratory complications. Cervical pain was eliminated or significantly reduced in all dogs that survived and none of the dogs had major residual neurological deficits.
Conclusions — Arthrodesis could not be confirmed on follow-up radiographs due to the presence of the polymethylmethacrylate; however, adequate stabilization of C1-C2 appears to have been achieved based on the resolution of clinical signs.
Clinical Relevance — Application of ventral pins and polymethylmethacrylate is an effective means of surgical treatment for congenital and traumatic AAI.     

Therapeutic hypothermia applicable to cardiac surgery

ObjectiveTo review the beneficial and adverse effects of therapeutic hypothermia (TH) applicable to cardiac surgery with cardiopulmonary bypass (CPB) in the contexts of various temperature levels and techniques for achieving TH.Databases usedMultiple electronic literature searches were performed using PubMed and Google for articles published from June 2012 to December 2014. Relevant terms (e.g. ‘hypothermia’, ‘cardiopulmonary bypass’, ‘cardiac surgery’, ‘neuroprotection’) were used to search for original articles, letters and reviews without species limitation. Reviews were included despite potential publication bias. References from the studies identified were also searched to find other potentially relevant citations. Abstracts, case reports, conference presentations, editorials and expert opinions were excluded.ConclusionsTherapeutic hypothermia is an essential measure of neuroprotection during cardiac surgery that may be achieved most effectively by intravascular cooling using hypothermic CPB. For most cardiac surgical procedures, mild to modest (32–36 °C) TH will be sufficient to assure neuroprotection and will avoid most of the adverse effects of hypothermia that occur at lower body core temperatures.     

Surgical Management of Multiple Congenital Intrahepatic Shunts in Two Dogs

Objective —To present details of an unusual type of portosystemic shunt and its surgical management in two dogs.
Animals —Two young dogs that had a tentative diagnosis of a portosystemic shunt on the basis of clinical signs and serum biochemical abnormalities. Abdominal ultrasonography and contrast portography demonstrated multiple intrahepatic shunts. In both cases, the multiple shunts arose from a single branch of the portal vein.
Outcome—It was possible to locate and attenuate flow through the shunts via a transportal venotomy under conditions of hepatic vascular occlusion. Clinical and biochemical abnormalities resolved after surgery in both dogs. Postoperative sonography revealed complete obliteration of the shunt plexus in one of the dogs.     

Hinged Ilizarov External Fixation for Correction of Antebrachial Deformities

Objective —To evaluate hinged circular external fixation for correction of antebrachial deformities in dogs.
Study Design —Uncontrolled clinical trial.
Animal Population —Seven client-owned dogs.
Methods —Six dogs had one radius corrected and one dog had both radii corrected. Preoperative planning included measurement of the craniocaudal and mediolateral angular deformities, rotational deformity, length deficit, origin of deformity, graphical or mathematical determination of the amplitude and direction of the actual limb deformity, and frame assembly.
Results —Preoperatively, function and cosmesis were assessed to be fair to poor in all dogs. Deformity correction started 48 to 60 hours postoperatively and ranged from 0.46 mm to 1.36 mm twice daily. Hospitalization time ranged from 4 to 6 days. Corrections were mostly made by the owners, at home. Lengthening and angular correction ranged from 3 to 38 mm and 18° to 48°. Mean residual deformities were 2.7% of radial length and 2.7°. The time duration with the circular external fixators in place ranged from 29 to 71 days. Two additional surgeries were necessary in one dog because of wire breakage. Mean follow-up was 40 months. Long-term function and cosmesis were good to excellent in all dogs.
Conclusion—Although complications were present in six of seven dogs, the outcome of hinged Ilizarov external fixation was successful in all dogs treated for deformities of the antebrachium.
Clinical Relevance —Despite complex preoperative planning, the placement of hinged circular external fixators is straightforward, and allows precise correction of complex antebrachial deformities with minimal tissue trauma.     

Mitral Valve Replacement in Dogs Surgical Technique and Postoperative Management

Although techniques for the perioperative management of patients undergoing mitral valve replacement have been well established in humans, the use of these techniques has not been widely accepted in veterinary practice. The purpose of this study is to demonstrate that low morbidity and mortality could be achieved in the dog undergoing mitral valve replacement. Nine mongrel dogs (25-45 kg body weight) were subject to left thoracotomy and mitral valve replacement using cardiopulmonary bypass (CPB). The average time on CPB was 1 hour with an aortic cross-clamping time of 40 minutes using chemically induced cardiac arrest. CPB was performed under conditions of moderate systemic hypothermia (28-30 degrees C) and hemodilution (hematocrit, 25-35%). Operative mortality was 22% (2/9) with one death from excessive bleeding and the other from cerebral air embolism. All other animals recovered and were clinically normal 3 weeks after surgery. The authors conclude that successful mitral valve replacement is possible in the large dog.     

Use of Colostomy to Manage Rectal Disease in Dogs

Objective — The purpose of this study was to develop a diverting colostomy technique for use in dogs.
Study Design — Clinical case series.
Animals — Five client-owned dogs presented for diseases requiring diverting colostomy during treatment.
Methods — Diverting colostomy was performed in five dogs. A ventral approach was used in the first dog and the colon was exteriorized adjacent to the linea alba. The technique used in the next four dogs involved creation of a left flank rod-supported loop colostomy in which the colon was exteriorized through a muscle-separating flank approach to the abdomen.
Results — Peritoneal leakage of fecal material resulted in the perioperative death of the first dog. The flank colostomies were maintained for times ranging from 3.5 weeks to 7 months. No major complications were observed, but skin excoriation occurred occasionally around the stomasites in all dogs.
Conclusion — Diverting colostomy is a technique that is suitable for use in treatment of dogs with obstruction or leakage involving the distal colon or rectum.     

Ventral Abdominal Approach for Laparoscopic Ovariectomy in Llamas

Objective —To evaluate a technique for laparoscopic ovariectomy by a ventral abdominal approach in the llama.
Study Design —Prospective evaluation.
Animal Population —Six healthy adult female llamas, aged 2 to 6 years.
Methods —Laparoscopic ovariectomy was performed with the llamas in a 30-degree Trendelenburg position. The mesovarium and proper ligament of the ovary were isolated, and two Hulka clips were placed in opposite directions across each mesovarium and proper ligament of the ovary. Ovaries were removed through either the instrument cannula or instrument portal.
Results —The ovaries, mesovarium, and proper ligaments of the ovaries were easily identified using laparoscopy by a ventral abdominal approach. The Hulka Clip Applicator was easy to use, and the Hulka Clips provided secure hemostasis of the vessels within the mesovarium. Mean duration of surgery was 35 minutes (range, 17 to 85 minutes). Two llamas were depressed after surgery but improved within 24 hours. No other complications occurred during an 18-month follow-up period.
Conclusions —Laparoscopic ovariectomy in the llama was facilitated by the use of Hulka Clips placed across the mesovarium and proper ligament of the ovary.
Clinical Relevance —Laparoscopic ovariectomy in the llama can be accomplished easily with few complications.     

Effect of modified ultrafiltration on cytokines and hemoconcentration in dogs undergoing cardiopulmonary bypass

Cardiac surgery using cardiopulmonary bypass (CPB) generates severe inflammatory reactions secondary to hemodilution and surgical stress. This study was conducted to evaluate whether modified ultrafiltration (MUF) could be performed safely and to clarify its effects during mitral valve repair in dogs in terms of hemodilution and the status of inflammatory cytokines. We retrospectively studied 38 dogs with mitral valve disease who underwent MUF immediately after mitral valve repair under CPB. To determine the effect of MUF, we measured the pre- and post-MUF blood dilution and blood cytokine levels. The levels of red blood cells, hematocrit (HCT), and albumin were significantly increased after MUF, whereas interleukin (IL)-6 levels were significantly increased from 24.3 (range 9.6–54.6) to 32.3 (15.9–65.1) pg/ml. The levels of IL-8 and IL-10 declined significantly after MUF, from 368.2 (246.1–669.4) and 45.4 (28.6–76.1) to 272.2 (174.1–414.4) and 28.8 (18.8–44.5) pg/ml, respectively. Our results demonstrated that MUF can be applied in dogs undergoing CPB and is effective in achieving hemoconcentration. Moreover, MUF may be useful for the removal of cytokines. Further studies are needed to validate these findings and clarify the effects of inflammatory cytokines after CPB.     

Use of Buccal Mucosal Flaps for the Correction of Congenital Soft Palate Defects in Three Dogs

Objective —To present an alternative surgical technique for the repair of soft palate defects in dogs.
Animal Population —Three Foxhound cross dogs.
Methods —Bilateral buccal mucosal flaps, based at the palatoglossal arches, were raised. One flap was rotated so that the mucosal side created the floor of the nasopharynx. The second flap was rotated so that the mucosal side formed the roof of the oropharynx. The mucosa of the remnant of the soft palate and the pharyngeal walls was incised and the flaps sutured to these free mucosal edges. The caudal ends of the two flaps were sutured to each other.
Results —Complete closure of the soft palate defect was obtained in all three dogs. The dogs were monitored for between 1.5 and 3 years postoperatively, and no long-term problems were encountered.
Conclusions —This surgical technique resulted in an excellent functional separation of the oropharynx and nasopharynx and allowed reconstruction of a large bilateral soft palate defect.
Clinical Relevance —By using the buccal mucosal flaps, as described in this report, a tension-free closure of large soft palate defects can be obtained, thereby eliminating a major cause of failure of this type of reconstructive surgery.     

Comparison of Hypothermic and Normothermic Spinal Cord Perfusion in the Dog

Lumbar dorsal laminectomies were performed on 24 dogs, and exposed spinal cords were subjected to various time-temperature combinations of perfusion according to the following schedule: 1) 30 minutes of hypothermic perfusion—6 dogs; 2) 30 minutes of normothermic perfusion—6 dogs; 3) 120 minutes of hypothermic perfusion—6 dogs; and 4) 120 minutes of normothermic perfusion—6 dogs.
Surgery, cord perfusion, and exposure of the dorsal aspects of the spinal cord to the epaxial musculature for 5 days following surgery produced histopathologic changes in the dorsal aspects of the cord, especially around the dorsal root area. Hypothermic spinal cord perfusion for 120 minutes produced a marked deleterious effect on normal spinal cord function and spinal cord tissue. Spinal cords exposed to 30 minutes of hypothermic or normothermic perfusion or 120 minutes of normothermic perfusion had less severe clinical and histopathologic changes than those exposed to 120 minutes of hypothermic perfusion. Hypothermic perfusion for 30 minutes and 120 minutes affected not only dorsal aspects of the cord, but also the grey matter. The most severe change in grey matter occurred in cords perfused for 120 minutes.     

The Effect of Laparoscopic Versus Open Ovariectomy on Postsurgical Activity in Small Dogs

Objective— To describe a technique for laparoscopic ovariectomy (LapOVE) in small dogs, and compare the surgical time, complications, and postoperative activity of dogs undergoing LapOVE to those undergoing conventional traditional open ovariectomy (OOVE).
Study Design— A randomized, controlled clinical trial.
Animals— Intact small breed (<10 kg) female dogs (n=20).
Methods— Ventral median celiotomy was performed for OOVE. A 2-midline portal technique using a 3.5 mm laparoscope port and a 6 mm instrument portal was used for LapOVE. An accelerometer was attached to the collar of each dog to record 24-hour preoperative and 48-hour postoperative activity. Total activity counts recorded before surgery were compared with total counts recorded after surgery. The percent change in counts after surgery was compared between OOVE- and LapOVE-treated dogs.
Results— No major complications occurred and surgical time for LapOVE was significantly longer than for OOVE cases ( P =.005). Dogs in the LapOVE group had a 25% decrease in total activity counts after surgery (95% confidence interval [CI]: 11–38%), whereas dogs in the OOVE group had a 62% decrease in total activity counts after surgery (95% CI: 48–76%).
Conclusions— Both procedures were performed with reasonable surgical times and without major complication. Postoperative activity, as measured by accelerometry, was significantly different between the 2 groups.
Clinical Relevance— Laparoscopy is a safe method for ovariectomy in small dogs and results in increased postoperative activity counts when compared with an open technique.     

Short-term performance of mitral valve replacement with porcine bioprosthetic valves in dogs

Porcine bioprosthetic valves cross-linked with glutaraldehyde and polyepoxy compound were newly developed for mitral valve replacement (MVR) in dogs. Five beagle dogs were performed a left thoracotomy and underwent MVR using the porcine bioprosthetic valves during cardiopulmonary bypass (CPB). A vein catheter inserted into right atrium and a vent catheter inserted into the right ventricle to drain. The hemodynamic conditions of CPB were excellent during surgery. The left atrial pressure was measured before and after MVR; there was no significant difference and it was normal. Thrombosis and the prosthetic valve regurgitation were not observed one week after MVR. Pressure half time (PHT) prolonged significantly (P<0.05) from 31.40 +/- 4.0 msec presurgery to 99.20 +/- 19.4 msec at seven days after MVR, although it indicated the normal range as the bioprosthetic valve. The symptom of the prosthetic valve failure was not observed. This study indicated that the MVR using porcine bioprosthetic valves under CPB might have been effective in dogs as a short-term evaluation.     

Transsphenoidal Hypophysectomy in Beagle Dogs: Evaluation of a Microsurgical Technique

Objective — Assessment of a microsurgical technique for transsphenoidal hypophysectomy in dogs.
Study Design — Prospective study using physical examination, pituitary function testing, computed tomography (CT), and histological examination at autopsy.
Animals or Sample Population — Eight laboratory beagle dogs.
Methods — Pituitary function was assessed before and at 10 weeks after hypophysectomy by combined administration of four releasing hormones (anterior pituitary), administration of haloperidol (pars intermedia), and infusion of hypertonic saline (posterior pituitary).
Results — CT imaging enabled accurate preoperative localization of the pituitary. Appropriate positioning and surgical technique facilitated exposure of the pituitary and its extraction without hemorrhage. Postoperative recovery was generally uncomplicated. None of die eight dogs had somatotropic, gonadotropic, lactotropic, melanotropic, or posterior pituitary responses to stimulation at 10 weeks after hypophysectomy. Four dogs (ACTH nonresponders) also had no cortico-tropic response and four (ACTH responders) had small but significant responses in the combined anterior pituitary function test. Adrenocortical atrophy was more pronounced in the ACTH nonresponders man in the responders. No residual pituitary tissue was found along the ventral hypothalamic diencephalon but nests of pituitary cells were found embedded in fibrous tissue in the sella turcica.
Conclusions — The surgical technique proved to be safe and effective. Microscopic nests of pituitary cells in the sella turcica may be responsible for residual corticotropic response to hypophysiotropic stimulation after hypophysectomy.
Clinical Relevance — The surgical technique may be used in the treatment of dogs with pituitary-dependent hyperadrenocorticism. The corticotropic response is the most sensitive criterion in assessing completeness of hypophysectomy in dogs.