QUANTITATIVE PLANAR AND VOLUMETRIC CARDIAC MEASUREMENTS USING 64 MDCT AND 3T MRI VS. STANDARD 2D AND M-MODE ECHOCARDIOGRAPHY: DOES ANESTHETIC PROTOCOL MATTER?

Cross-sectional imaging of the heart utilizing computed tomography and magnetic resonance imaging (MRI) has been shown to be superior for the evaluation of cardiac morphology and systolic function in humans compared to echocardiography. The purpose of this prospective study was to test the effects of two different anesthetic protocols on cardiac measurements in 10 healthy beagle dogs using 64-multidetector row computed tomographic angiography (64-MDCTA), 3T magnetic resonance (MRI) and standard awake echocardiography. Both anesthetic protocols used propofol for induction and isoflourane for anesthetic maintenance. In addition, protocol A used midazolam/fentanyl and protocol B used dexmedetomedine as premedication and constant rate infusion during the procedure. Significant elevations in systolic and mean blood pressure were present when using protocol B. There was overall good agreement between the variables of cardiac size and systolic function generated from the MDCTA and MRI exams and no significant difference was found when comparing the variables acquired using either anesthetic protocol within each modality. Systolic function variables generated using 64-MDCTA and 3T MRI were only able to predict the left ventricular end diastolic volume as measured during awake echocardiogram when using protocol B and 64-MDCTA. For all other systolic function variables, prediction of awake echocardiographic results was not possible (P = 1). Planar variables acquired using MDCTA or MRI did not allow prediction of the corresponding measurements generated using echocardiography in the awake patients (P = 1). Future studies are needed to validate this approach in a more varied population and clinically affected dogs.

Effects of two different anesthetic protocols on cardiac flow measured by two dimensional phase contrast magnetic resonance imaging.

Companion animals are routinely anesthetized or heavily sedated for cardiac MRI studies, however effects of varying anesthetic protocols on cardiac function measurements are incompletely understood. The purpose of this prospective study was to compare effects of two anesthetic protocols (Protocol A: Midazolam, fentanyl; Protocol B: Dexmedetomidine) on quantitative and qualitative blood flow values measured through the aortic, pulmonic, mitral, and tricuspid valves using two-dimensional phase contrast magnetic resonance imaging (2D PC MRI) in healthy dogs. Mean flow per heartbeat values through the pulmonary artery (Qp) and aorta (Qs) were compared to right and left ventricular stroke volumes (RVSV, LVSV) measured using a reference standard of 2D Cine balanced steady-state free precession MRI. Pulmonary to systemic flow ratio (Qp/Qs) was also calculated. Differences in flow and Qp/Qs values generated using 2D PC MRI did not differ between the two anesthetic protocols (P = 1). Mean differences between Qp and RVSV were 3.82 ml/beat (95% limits of agreement: 3.62, -11.26) and 1.9 ml/beat (-7.86, 11.66) for anesthesia protocols A and B, respectively. Mean differences between Qs and LVSV were 1.65 ml/beat (-5.04, 8.34) and 0.03 ml/beat (-4.65, 4.72) for anesthesia protocols A and B, respectively. Mild tricuspid or mitral reflux was seen in 2/10 dogs using 2D PC MRI. No aortic or pulmonic insufficiency was observed. Findings from the current study indicated that these two anesthetic protocols yield similar functional measures of cardiac blood flow using 2D PC MRI in healthy dogs. Future studies in clinically affected patients are needed.

Systemic hypertension and hypertensive retinopathy following PPA overdose in a dog.

A 4 yr old spayed female Labrador retriever was examined 4 hr after ingesting an overdose of phenylpropanolamine (PPA). Clinical signs included anxiety, piloerection, mucosal ulceration, cardiac arrhythmia, mydriasis, and hyphema. Clinicopathologic abnormalities included elevated creatine kinase (CK) and aspartate aminotransferase (AST), proteinuria, and pigmenturia. Ventricular tachycardia and severe systemic hypertension were documented. Hyphema and retinal detachment were documented oculus uterque (OU). Phenoxybenzamine, sotalol, and esmolol resolved the ventricular tachycardia, and blood pressure was controlled with nitroprusside. All clinicopathologic and cardiac abnormalities resolved within 7 days, and ocular changes resolved within 1 mo. Monitoring of blood pressure and rapid pharmacologic intervention were successful in controlling hypertension secondary to PPA overdose and minimizing retinal damage.

Echocardiographic values for normal conditioned and unconditioned North American whippets.

BACKGROUND: Echocardiographic reference intervals have not been reported for North American whippets, or for whippets that have undergone pet-level athletic training. OBJECTIVES: To develop normal echocardiographic reference intervals for North American whippets and investigate differences in echocardiographic parameters based on athletic conditioning in pet whippets engaged in competitive sports. ANIMALS: One-hundred healthy North American whippets. METHODS: Dogs were examined at national shows between 2005 and 2009. Echocardiographic reference intervals were constructed and the effect of athletic conditioning on parameters of structure and function was assessed. RESULTS: Two dimensional, M-mode, Doppler and tissue Doppler reference ranges for healthy North American whippets are presented. Measures of left ventricular (LV) chamber diameter were larger in conditioned whippets (N = 25) and remained significantly larger than in unconditioned whippets (N = 16) when normalized for weight using allometric equations. Calculated LV mass was higher in conditioned dogs than in unconditioned dogs, and this difference persisted when LV mass was normalized by weight. Mitral E velocity was higher in conditioned dogs than in unconditioned dogs, whereas E/A and measures related to systolic function were not different. CONCLUSIONS AND CLINICAL IMPORTANCE: Pet whippets in peak athletic condition have larger hearts than do less conditioned whippets, but measures of systolic function are similar. Whippet pet athletes may show eccentric LV hypertrophy at peak condition. Normal values for cardiac size and function in North American whippets might be considered abnormal if population-specific whippet reference intervals are not used in analysis.

Ocular lesions associated with systemic hypertension in dogs: 65 cases (2005-2007).

OBJECTIVE: To characterize ocular findings in hypertensive dogs, determine prevalence of hypertension in dogs with ocular disease suggestive of hypertension, and examine possible relationships between degree of hypertension and ocular disease. DESIGN: Retrospective case series. ANIMALS: 65 dogs initially referred for blood pressure measurement (n = 22), ophthalmic examination (25), or both (18). PROCEDURES: Medical records were reviewed to identify dogs examined at the teaching hospital that underwent a complete ophthalmic examination and blood pressure measurement within a 24-hour period between January 1, 2005, and December 31, 2007. Signalment, history, blood pressure measurements, ophthalmic examination findings, and any vasoactive drug treatments were recorded. Ocular lesions considered likely to be associated with systemic hypertension included retinal hemorrhage, retinal detachment, hyphema, tortuous vessels, and subretinal edema. RESULTS: Of the 65 dogs, 42 were hypertensive (systolic blood pressure ≥ 160 mm Hg) and 23 were normotensive. Sixty-two percent (26/42) of hypertensive dogs had ≥ 1 type of ocular lesion identified. Retinal hemorrhage was the most common ocular lesion in hypertensive dogs (17/42 [40%]). The presence of ≥ 1 type of ocular lesion had moderate sensitivity and specificity of 62% and 61 %, respectively, for identification of hypertension. Fifteen of the 25 (60%) dogs referred for blood pressure measurement after initial ophthalmic examination were found to be hypertensive. CONCLUSIONS AND CLINICAL RELEVANCE: Ocular lesions are common in dogs with systemic hypertension. Dogs with hypertension or diseases associated with hypertension should be monitored carefully for evidence of ocular target organ damage, and hypertension should be systematically ruled out in dogs with characteristic ocular lesions.

Comparison of plasma cardiac troponin I concentrations among dogs with cardiac hemangiosarcoma, noncardiac hemangiosarcoma, other neoplasms, and pericardial effusion of nonhemangiosarcoma origin.

OBJECTIVE: To determine whether plasma cardiac troponin I (cTnl) concentrations can be used to identify cardiac involvement in dogs with hemangiosarcoma, exclude cardiac hemangiosarcoma in dogs with noncardiac hemangiosarcoma, and identify cardiac hemangiosarcoma in dogs with pericardial effusion. DESIGN: Cohort study. ANIMALS: 57 dogs (18 with confirmed [5 dogs] or suspected [13] cardiac hemangiosarcoma, 14 with confirmed hemangiosarcoma involving sites other than the heart [noncardiac hemangiosarcoma], 10 with pericardial effusion not caused by hemangiosarcoma, and 15 with noncardiac nonhemangiosarcoma neoplasms). PROCEDURES: Plasma cTnl concentration was measured, and thoracic radiography, abdominal ultrasonography, and echocardiography were performed in each dog. The cTnl concentration was compared among groups. RESULTS: Median plasma cTnl concentration in dogs with cardiac hemangiosarcoma was significantly higher than the concentration in each of the other groups. A plasma cTnl concentration > 0.25 ng/mL could be used to identify cardiac involvement in dogs with hemangiosarcoma at any site (sensitivity, 78%; specificity, 71 %). A plasma cTnl concentration > 0.25 ng/mL could be used to identify cardiac hemangiosarcoma in dogs with pericardia effusion (sensitivity, 81%; specificity, 100%). CONCLUSIONS AND CLINICAL RELEVANCE: The median plasma cTnl concentration was higher in dogs with cardiac hemangiosarcoma, compared with the median concentration in dogs with hemangiosarcoma at other sites, dogs with other neoplasms, and dogs with pericardial effusion not caused by hemangiosarcoma. The plasma cTnl concentration may be used to identify cardiac involvement in dogs with hemangiosarcoma and to identify cardiac hemangiosarcoma in dogs with pericardial effusion.

Use of radiographic measurements to diagnose stage B2 preclinical myxomatous mitral valve disease in dogs.

OBJECTIVE: To investigate the usefulness of radiographic measures of the left atrium and ventricle as surrogates for echocardiographic criteria in identifying dogs with stage B2 preclinical myxomatous mitral valve disease (MMVD). ANIMALS: 56 client-owned dogs with preclinical mitral regurgitation attributed to MMVD examined between April 19, 2016, and November 22, 2017. PROCEDURES: Medical records were retrospectively searched, and data collected included age, body weight, heart murmur grade, and echocardiographic and radiographic measurements. Dogs were grouped according to whether they did (case dogs) or did not (control dogs) meet echocardiographic criteria used to identify dogs with stage B2 MMVD. Measurements for lateral thoracic radiographic variables normalized to vertebral body units (VBUs) were obtained, and results were analyzed to identify variables that could best discriminate between case and control dogs. RESULTS: Three radiographic variables of left atrial size (vertebral left atrial size [VLAS], left atrial width, and the combined variable of VLAS + left atrial width) most accurately distinguished control dogs from case dogs, and the VLAS was the simplest and fastest to perform in a clinical setting. The optimal cutoff for VLAS was 2.5 VBUs (sensitivity, 70%; specificity, 84%; and likelihood ratio, 4.38), with VLAS ≥ 2.5 VBUs for case dogs. The maximum specificity cutoff for VLAS was 3.0 VBUs (sensitivity, 40%; specificity, 96%; and likelihood ratio, 10.0), with VLAS ≥ 3.0 VBUs for case dogs. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that when echocardiography is unavailable, radiographic VLAS ≥ 3 VBUs could be used with minimal risk of false-positive diagnosis of stage B2 MMVD in dogs.

Temporal changes in clinical and radiographic variables in dogs with preclinical myxomatous mitral valve disease: The EPIC study.

BACKGROUND: The Evaluation of pimobendan in dogs with cardiomegaly caused by preclinical myxomatous mitral valve disease (EPIC) study monitored dogs with myxomatous mitral valve disease (MMVD) as they developed congestive heart failure (CHF). OBJECTIVES: To describe the changes in clinical and radiographic variables occurring as dogs with MMVD and cardiomegaly develop CHF, compared to similar dogs that do not develop CHF. ANIMALS: One hundred and thirty-five, and 73 dogs that did or did not develop CHF, respectively. MATERIALS AND METHODS: The following variables were evaluated in 2 groups of dogs (dogs that did or did not develop CHF): Heart rate (HR), clinic respiratory rate (RR), home-measured resting respiratory rate (RRR), rectal temperature (RT), body weight (BW), and vertebral heart sum (VHS). Absolute value and rate of change of each variable were calculated for each day a dog was in study. Daily means were calculated and plotted against time. The onset of CHF or last visit before leaving the study were set as reference time points. RESULTS: The most extreme values and rate of change occurred in variables immediately before onset of CHF. Vertebral heart sum increased earliest. Heart rate, RR, and RRR also increased. Rectal temperature and BW decreased. Increases in RR and RRR were most extreme and occurred immediately before CHF. CONCLUSIONS AND CLINICAL IMPORTANCE: Dogs with MMVD and cardiomegaly experience increases in HR, RR, RRR, and VHS, and decreases in BW and RT as they develop CHF. The variables with highest absolute change and rate of change were RR and RRR. These findings reinforce the value of RR and RRR as indicators of impending or incipient CHF.

Elevations in sex hormones in dogs with sudden acquired retinal degeneration syndrome (SARDS).

Dogs diagnosed with sudden acquired retinal degeneration syndrome (SARDS) commonly are presented with concurrent clinical, physical, and historical findings consistent with hyperadreno-corticism (HAC) at the time of vision loss. Thirteen dogs diagnosed with SARDS on the basis of complete ophthalmic examination and extinguished bright-flash electroretinogram were evaluated for steroid hormonal abnormalities. Signalment, case history, physical examination, and clinicopathological findings were recorded. Serum cortisol and sex-hormone concentrations were measured before and after adrenocorticotropic hormone (ACTH) stimulation. Clinical signs of HAC, systemic hypertension, and proteinuria were commonly found in dogs with SARDS. Elevations in one or more sex hormones were found in 11 (85%) of 13 dogs (95% confidence interval [CI] 65% to 100%); cortisol was elevated in nine (69%) of 13 dogs (95% CI 44% to 94%). A minority of dogs (three [23%] of 13; 95% CI 0.2% to 46%) exhibited only an increase in adrenal sex hormones. Only one dog had completely normal ACTH stimulation test results. Symptoms of HAC were associated with abnormal ACTH stimulation results. Routine ACTH stimulation testing to evaluate cortisol and sex hormones, blood pressure screening, and urinalysis are recommended in these animals.

Chylothorax associated with a congenital peritoneopericardial diaphragmatic hernia in a dog.

A 2-year-old dog was presented with a 3-month history of increasing respiratory effort and rate, inappetence, and lethargy. Chest radiographs demonstrated significant pleural effusion, which was consistent with chyle on biochemical and cytological evaluations. Further diagnostic evaluation, including a thoracic computed tomographic scan, revealed a peritoneopericardial diaphragmatic hernia (PPDH) resulting in a large, fat-attenuating mass within the pericardium. The dog was taken to surgery for repair of the PPDH, pericardectomy, and cisterna chyli ablation. Rapid and permanent resolution of the chylothorax occurred postoperatively. This is the first reported case of chylothorax secondary to PPDH.

Long-term incidence and risk of noncardiovascular and all-cause mortality in apparently healthy cats and cats with preclinical hypertrophic cardiomyopathy.

BACKGROUND: Epidemiologic knowledge regarding noncardiovascular and all-cause mortality in apparently healthy cats (AH) and cats with preclinical hypertrophic cardiomyopathy (pHCM) is limited, hindering development of evidence-based healthcare guidelines. OBJECTIVES: To characterize/compare incidence rates, risk, and survival associated with noncardiovascular and all-cause mortality in AH and pHCM cats. ANIMALS: A total of 1730 client-owned cats (722 AH, 1008 pHCM) from 21 countries. METHODS: Retrospective, multicenter, longitudinal, cohort study. Long-term health data were extracted by medical record review and owner/referring veterinarian interviews. RESULTS: Noncardiovascular death occurred in 534 (30.9%) of 1730 cats observed up to 15.2 years. Proportion of noncardiovascular death did not differ significantly between cats that at study enrollment were AH or had pHCM (P = .48). Cancer, chronic kidney disease, and conditions characterized by chronic weight-loss-vomiting-diarrhea-anorexia were the most frequently recorded noncardiovascular causes of death. Incidence rates/risk of noncardiac death increased with age in AH and pHCM. All-cause death proportions were greater in pHCM than AH (65% versus 40%, respectively; P < .001) because of higher cardiovascular mortality in pHCM cats. Comparing AH with pHCM, median survival (study entry to noncardiovascular death) did not differ (AH, 9.8 years; pHCM, 8.6 years; P = .10), but all-cause survival was significantly shorter in pHCM (P = .0001). CONCLUSIONS AND CLINICAL IMPORTANCE: All-cause mortality was significantly greater in pHCM cats due to disease burden contributed by increased cardiovascular death superimposed upon noncardiovascular death.

Efficacy of atenolol as a single antihypertensive agent in hyperthyroid cats.

beta-Adrenergic blockers, particularly atenolol, are often recommended for the tachycardia and hypertension that accompany hyperthyroidism; however, the effects of monotherapy with atenolol on both systolic blood pressure (SBP) and heart rate (HR) have not been reported. Twenty hyperthyroid cats with SBP > or = 160 mmHg were studied retrospectively to investigate the SBP and HR lowering effects of atenolol. Median pre-treatment SBP and HR for all cats were 186.5 mmHg and 231 beats/min, respectively. All cats were treated with atenolol at a dosage of 1-2 mg/kg PO q 12h for a minimum of 5 days prior to reassessment and treatment with radioactive iodine. SBP and HR both decreased following atenolol therapy in this group of cats to median values of 171.5 mmHg (P=0.0088) and 185/min (P=0.0003). However, when successful clinical control of hypertension was defined as a post-treatment SBP < 160 mmHg, atenolol monotherapy was ineffective in 70% of the cases. There was no statistically significant difference in baseline serum total thyroxine or atenolol dosage between clinical responders and non-responders. While atenolol effectively reduces HR in most cats with hyperthyroidism, elevated SBP is poorly controlled, and the addition of another vasodilator such as amlodipine or an angiotensin converting enzyme inhibitor is needed to treat associated hypertension.

ACVIM consensus statement: Guidelines for the identification, evaluation, and management of systemic hypertension in dogs and cats.

An update to the 2007 American College of Veterinary Internal Medicine (ACVIM) consensus statement on the identification, evaluation, and management of systemic hypertension in dogs and cats was presented at the 2017 ACVIM Forum in National Harbor, MD. The updated consensus statement is presented here. The consensus statement aims to provide guidance on appropriate diagnosis and treatment of hypertension in dogs and cats.

International collaborative study to assess cardiovascular risk and evaluate long-term health in cats with preclinical hypertrophic cardiomyopathy and apparently healthy cats: The REVEAL Study.

BACKGROUND: Hypertrophic cardiomyopathy is the most prevalent heart disorder in cats and principal cause of cardiovascular morbidity and mortality. Yet, the impact of preclinical disease is unresolved. HYPOTHESIS/OBJECTIVES: Observational study to characterize cardiovascular morbidity and survival in cats with preclinical nonobstructive (HCM) and obstructive (HOCM) hypertrophic cardiomyopathy and in apparently healthy cats (AH). ANIMALS: One thousand seven hundred and thirty client-owned cats (430 preclinical HCM; 578 preclinical HOCM; 722 AH). METHODS: Retrospective multicenter, longitudinal, cohort study. Cats from 21 countries were followed through medical record review and owner or referring veterinarian interviews. Data were analyzed to compare long-term outcomes, incidence, and risk for congestive heart failure (CHF), arterial thromboembolism (ATE), and cardiovascular death. RESULTS: During the study period, CHF, ATE, or both occurred in 30.5% and cardiovascular death in 27.9% of 1008 HCM/HOCM cats. Risk assessed at 1, 5, and 10 years after study entry was 7.0%/3.5%, 19.9%/9.7%, and 23.9%/11.3% for CHF/ATE, and 6.7%, 22.8%, and 28.3% for cardiovascular death, respectively. There were no statistically significant differences between HOCM compared with HCM for cardiovascular morbidity or mortality, time from diagnosis to development of morbidity, or cardiovascular survival. Cats that developed cardiovascular morbidity had short survival (mean ± standard deviation, 1.3 ± 1.7 years). Overall, prolonged longevity was recorded in a minority of preclinical HCM/HOCM cats with 10% reaching 9-15 years. CONCLUSIONS AND CLINICAL IMPORTANCE: Preclinical HCM/HOCM is a global health problem of cats that carries substantial risk for CHF, ATE, and cardiovascular death. This finding underscores the need to identify therapies and monitoring strategies that decrease morbidity and mortality.

Sildenafil citrate therapy in 22 dogs with pulmonary hypertension.

BACKGROUND: Pulmonary hypertension (PH) is a disease condition characterized by abnormally increased pulmonary artery pressures and often is associated with a poor prognosis. Sildenafil is a phosphodiesterase inhibitor that causes pulmonary arterial vasodilation and reduction in pulmonary artery pressures. HYPOTHESIS: Treatment with sildenafil will improve echocardiographic determinants of PH in dogs, while also improving quality of life and survival. ANIMALS: Twenty-two dogs with clinical and echocardiographic evidence of pulmonary hypertension. METHODS: A retrospective study evaluating the effects of sildenafil on physical examination, ECG and radiographic findings, blood pressure and echocardiographic findings of PH, clinical score, and outcome was completed. PH was defined as a peak tricuspid regurgitation flow velocity > or = 2.8 m/s or a peak pulmonic insufficiency flow velocity > or = 2.2 m/s. RESULTS: Sixteen of 22 dogs with PH were elderly females of small body size. Their clinical score was significantly improved (P = .0003) with sildenafil treatment, but physical examination findings remained unchanged. Heart rate, respiratory rate, vertebral heart size, ECG heart rate, and systolic blood pressure did not change significantly with sildenafil treatment (P > .05). Peak tricuspid regurgitation flow velocities did not change significantly with the treatment of sildenafil, but selected systolic time intervals were significantly improved. Survival times for all dogs ranged from 8 to > 734 days. CONCLUSIONS AND CLINICAL IMPORTANCE: Sildenafil did not significantly lower the degree of measurable PH in dogs. Clinical improvement and increased quality of life was seen with sildenafil treatment, despite lack of significant change in other variables.

Echocardiographic effects of dexmedetomidine-ketamine in chinchillas ( Chinchilla lanigera).

Alpha2-agonist anesthetic combinations are often used in rodent anesthesia but no information about their effects on cardiac function in chinchillas exists. The purpose of this study was to utilize echocardiography to evaluate the cardiovascular effects of dexmedetomidine-ketamine anesthesia in chinchillas. Echocardiographic examinations were performed in eight adult chinchillas under manual restraint and following dexmedetomidine (0.015 mg/kg) and ketamine (4 mg/kg) administration. Dexmedetomidine-ketamine anesthesia resulted in a significantly decreased heart rate, fractional shortening, cardiac output, and flow velocity across the aortic and pulmonic valves, and significantly increased left ventricular internal diameter in systole. The observed changes in echocardiographic parameters are similar to those previously reported in chinchillas anesthetized with isoflurane.

Subdural hematoma of the brainstem in a dog: magnetic resonance findings and treatment.

An 8-year-old, spayed female Dalmatian with a history of seizures was evaluated for cervical pain and bilateral scleral hemorrhages. Diagnostic evaluations revealed a mass displacing the ventral brainstem on magnetic resonance imaging (MRI). The mass was surgically removed and histologically confirmed to be a hematoma. The dog's neurological signs resolved completely after surgery. Although extradural, subdural, subarachnoid, and intraparenchymal hemorrhages have been reported in dogs and cats, this is the first known report of a subdural hematoma of the ventral brainstem in a dog. On the basis of the history and the appearance of the subdural hematoma on MRI, a traumatic event during the seizure episodes was considered the most likely cause of the subdural hematoma in this case.

Aortic tear and dissection related to connective tissues abnormalities resembling Marfan syndrome in a Great Dane.

Aortic tears and acute aortic dissection are rarely reported in dogs. This report describes a case of aortic dissection and probable sinus of Valsalva rupture in a young Great Dane with associated histopathologic findings suggestive of a connective tissue abnormality.