ECHOCARDIOGRAPHIC PARAMETERS IN EIGHT ADULT TIGERS ( PANTHERA TIGRIS) DURING TWO PHASES OF AN ANESTHETIC PROTOCOL.

Eight adult tigers ( Panthera tigris) underwent a complete echocardiographic examination following sedation with medetomidine, midazolam, and induction of general anesthesia using ketamine and isoflurane (phase 1). Atipamezole was used to antagonize medetomidine (phase 2) and a second echocardiographic examination was performed. Physiologic tricuspid and pulmonic regurgitations were common findings in the sample population and one tiger was excluded from final analyses due to the finding of a ventricular septal defect. Measurements and mean arterial pressure were assessed for statistically significant differences between the two examination phases as well as gender and weight. There was a statistically significant difference between interventricular septum thickness at end systole, ejection fraction, and mean arterial pressure between anesthetic phases while fractional shortening and left ventricular internal dimension at end-systole approached, but did not reach, statistical significance between phases. Weight was found to be a statistically significant predictor of stroke volume and left ventricular internal dimension at end-diastole. The echocardiographic measurements obtained during this study can be used as guidelines for future examinations in adult tigers. The effects of medetomidine on these measurements and systolic function should be taken into account when performing echocardiograms and monitoring anesthetic events.

Pericardial Mesothelioma in a Yellow-naped Amazon Parrot (Amazona auropalliata).

A 37-year-old female yellow-naped Amazon parrot (Amazona auropalliata) was presented with a history of lethargy, inappetence, and decreased vocalizations. On examination, the coelom was moderately distended and palpated fluctuant, and the heart was muffled on auscultation. Coelomic ultrasound, coelomocentesis, and radiographs were performed and revealed an enlarged cardiac silhouette and marked coelomic effusion. Pericardial effusion was confirmed by echocardiography. A well-circumscribed, hyperechoic soft tissue density was observed at the level of the right atrium on initial echocardiography; however, a cardiac mass was not identified by computed tomography scan or repeat echocardiograms. Ultrasound-guided pericardiocentesis was performed under anesthesia, and cytology results were consistent with hemorrhage; no neoplastic cells were identified. A repeat echocardiogram 4 days after pericardiocentesis revealed recurrence of the pericardial effusion. Due to the grave prognosis, the owners declined endoscopic pericardiectomy, and the patient died the following day. On postmortem examination, the pericardial surface of the heart was covered in a white to yellow, multinodular mass layer. Histologic analysis revealed a multinodular mass extending from the atria, running along the epicardium distally, and often extending into the myocardium. Neoplastic cells present in the heart mass and pericardium did not stain with a Churukian-Schenk stain, and thyroglobulin immunohistochemistry was negative. Cytokeratin and vimentin stains showed positive expression in the neoplastic cells within the mass. These results are consistent with a diagnosis of mesothelioma. This is the first report of mesothelioma in a psittacine bird.

Selected clinical, biochemical, and electrolyte alterations in anesthetized captive tigers (Panthera tigris) and lions (Panthera leo).

A prospective study to assess changes in selected plasma biochemistry and electrolyte values, plasma insulin and aldosterone concentrations, and electrocardiography (ECG) was performed on eight female captive tigers (Panthera tigris) and three lions (Panthera leo) undergoing general anesthesia for elective laparoscopic ovariectomy. Each animal was sedated with medetomidine (18-25 microg/kg) and midazolam (0.06-0.1 mg/kg) intramuscularly, and anesthesia was induced with ketamine (1.9-3.5 mg/kg) intramuscularly and maintained with isoflurane. Venous blood samples were collected and analyzed for plasma biochemistry parameters and insulin and aldosterone concentrations. An ECG was recorded at the time of each blood sample collection. Mean plasma potassium, glucose, phosphorus, and aldosterone concentrations increased during anesthesia (P < or = 0.05). One tiger developed hyperkalemia (6.5 mmol/L) 2.5 hr after anesthetic induction. Plasma insulin concentrations were initially below the low end of the domestic cat reference interval (72-583 pmol/L), but mean insulin concentration increased (P < or = 0.05) over time compared with the baseline values. Three tigers and two lions had ECG changes that were representative of myocardial hypoxemia. Based on these results, continuous monitoring of clinical and biochemical alterations during general anesthesia in large nondomestic felids is warranted, and consideration should be given to reversal of medetomidine in these animals should significant changes in electrolytes or ECG occur.

Induction and recovery characteristics and cardiopulmonary effects of sevoflurane and isoflurane in bald eagles.

OBJECTIVE: To compare induction and recovery characteristics and cardiopulmonary effects of isoflurane and sevoflurane in bald eagles. Animals-17 healthy adult bald eagles. PROCEDURES: Anesthesia was induced with isoflurane or sevoflurane delivered in oxygen via a facemask in a crossover design with 4 weeks between treatments. Eagles were intubated, allowed to breathe spontaneously, and instrumented for cardiopulmonary measurements. Time to induction, extubation, and recovery, as well as smoothness of recovery, were recorded. RESULTS: Administration of sevoflurane resulted in a significantly quicker recovery, compared with isoflurane. Temperature, heart rate, and respiratory rate significantly decreased over time, whereas systolic (SAP), diastolic (DAP), and mean arterial blood pressure (MAP) significantly increased over time with each treatment. Temperature, heart rate, SAP, DAP, and MAP were significantly higher with isoflurane. Blood pH significantly decreased, whereas PaCO(2) significantly increased over time with each treatment. Bicarbonate and total carbon dioxide concentrations significantly increased over time with each treatment; however, there was a significant time-treatment interaction. The PaO(2) and arterial oxygen saturation increased over time with isoflurane and decreased over time with sevoflurane with a significant time-treatment interaction. Six eagles developed cardiac arrhythmias with isoflurane, as did 4 with sevoflurane anesthesia. CONCLUSIONS AND CLINICAL RELEVANCE: Isoflurane and sevoflurane administration resulted in smooth, rapid induction of and recovery from anesthesia similar to other species. Isoflurane administration resulted in tachycardia, hypertension, and more arrhythmias, compared with sevoflurane. Sevoflurane was associated with fewer adverse effects and may be particularly beneficial in compromised bald eagles.

Endocardial fibroelastosis in two related tiger cubs (Panthera tigris).

Two tiger cubs (Panthera tigris) from the same litter were evaluated for suspected cardiac disease. Two cubs with a dilated cardiomyopathy phenotype were diagnosed with endocardial fibroelastosis based on necropsy and histopathologic examinations. Echocardiography revealed salient anatomic and functional aspects of this cardiac disorder. This is the first report of endocardial fibroelastosis in this species.

Cardiovascular involvement in 8 dogs with blastomyces dermatitidis infection.

BACKGROUND: Blastomycosis is a common systemic fungal infection in dogs. HYPOTHESIS: Dogs with cardiovascular involvement may have abnormalities in electrical conduction and valvular function, and may have a worse prognosis. ANIMALS: Eight client-owned animals. METHODS: Dogs with cardiovascular lesions caused by blastomycosis were identified from retrospective evaluation of medical records. RESULTS: Five dogs had de novo infections and 3 had recurrences of previously treated infections. Harsh labored breathing, lethargy, and anorexia were the most common historic complaints. Three dogs had syncope. Physical examination and clinicopathologic data were typical of blastomycosis and included dyspnea, increased lung sounds, and lethargy. In addition, 3 dogs had heart murmurs and 1 had a third-degree atrioventricular block. Four dogs had myocarditis and 2 had pericarditis or epicarditis. Two dogs had cardiac signs attributed to extracardiac compression by fungal granulomas and clinical signs were relieved by treatment. Half of the remaining 6 dogs were euthanized; 2 of these were not treated. Of the remaining 3 dogs, 1 dog died acutely while sleeping; the second died intraoperatively during an attempt to place an epicardial pacemaker; and the third had Blastomyces-induced endocarditis and died of heart failure. CONCLUSIONS AND CLINICAL IMPORTANCE: Blastomycosis should be considered in the differential diagnosis of dogs from endemic areas with inflammatory myocarditis, heart block, heart base or intracardiac mass lesions, syncope, or endocarditis.

Nutritional and herbal therapies in the treatment of heart disease in cats and dogs.

Nutritional supplements such as L-carnitine and taurine have been found to be beneficial in dogs and cats with certain cardiac diseases. However, not all animals with cardiac disease respond to nutritional supplementation, which means that further work must be done to identify causes of cardiac disease. Herbal therapies have been used in dogs and cats based on information available from their use in humans. This paper reviews the possible benefits and side effects of L-carnitine, taurine, and herbal supplements.

Giant platelet disorder in the Cavalier King Charles Spaniel.

OBJECTIVE: The aim of this study was to describe the clinical, functional, and morphologic characteristics of platelets in Cavalier King Charles Spaniel dogs (Cavaliers). MATERIALS AND METHODS: Blood from 69 clinically normal Cavaliers was collected and anticoagulated with ethylenediamine-tetraacetic acid (EDTA) and citrate. Automated and manual platelet counts were obtained. Percent platelet aggregation in response to ADP (2, 4, 8, 16, and 32 microM) was determined. Electron microscopy was performed to examine platelet internal morphology and dense granule distribution. A cardiologist recorded the quality of murmurs. RESULTS: Thrombocytopenia (<100,000/microL) was present in 51.43% (36/69) of Cavaliers. Macrothrombocytes (>3 microm) were present in 33.33% (22/69). Mean manual platelet count was 118,770/microL. Manual (EDTA blood) and automated (EDTA and citrated blood) methods of platelet counting were correlated. Prevalence of cardiac murmurs was 38% (26/69). There was no association between affected dogs and murmur, signalment, or coat color. Mean percent platelet aggregation was significantly higher in controls than in Cavaliers (79% vs 38%, p=0.001). Response to ADP was unaffected by thrombocytopenia, macrothrombocytes, murmur, or any combination thereof. Platelet electron microscopy showed normal and giant sized platelets with normal internal morphology. CONCLUSIONS: A benign inherited giant platelet disorder affects approximately 50% of Cavalier King Charles Spaniels. It is characterized by thrombocytopenia, macrothrombocytes, or decreased platelet aggregation in response to ADP. Platelet ultrastructure is normal. Citrated or EDTA blood provides accurate platelet counts. Further studies are indicated to determine platelet glycoprotein structure and any association with mitral endocardiosis. Cavaliers may be useful models of inherited giant platelet disorders.

Diagnosis of congenital cardiac right-to-left shunts with 99mTc-macroaggregated albumin.

Diagnosing right-to-left congenital cardiac shunts can be difficult. Cardiac catheterization and angiocardiography represent the traditional gold standard for diagnosis, but they are invasive. Nuclear scintigraphy using 99mTc-macroaggregated albumin (MAA) has been employed in humans as an alternate method of diagnosis. This study reviews eight dogs presented for evaluation of a suspect right-to-left cardiac shunt that were examined using 99mTc-MAA. In all, 2-4 mCi (74-148 MBq) of reduced particle 99mTc-MAA were injected IV in a cephalic vein and static images of the whole body, including right and left lateral, dorsal, and ventral views, were acquired for 60 s and stored into a 256 x 256 x 16 matrix. Shunt fractions were calculated. One dog with radiopharmaceutical distribution limited to the lungs did not have a shunt. Seven dogs had distribution of the radiopharmaceutical outside the pulmonary capillary bed, indicating bypassing of the pulmonary capillary circulation due to a right-to-left shunt. Four dogs had 99mTc-MAA within the brain. Three dogs that did not have brain uptake, but instead had a sharp cutoff of radioactivity at the level of the front limbs and neck, were diagnosed with reverse patent ductus arteriosus (PDA). The asymmetric distribution of the radiopharmaceutical is due to the location of the shunt, distal to the brachiocephalic trunk and left subclavian artery. Shunt fractions of dogs with extrapulmonary radioactivity ranged from 40% to 59%. Nuclear scintigraphy with 99mTc-MAA is a quick alternative method of diagnosing right-to-left cardiac shunts that permits quantification of shunt fraction. Distinguishing between reverse PDA and other right-to-left shunts may be possible based on the radiopharmaceutical distribution.