Association of age and heart rate with pulsed-wave Doppler measurements in healthy, nonsedated cats

BACKGROUND: Associations of age and heart rate with blood flow velocities and durations assessed by pulsed-wave (PW) Doppler echocardiography in cats are incompletely understood. OBJECTIVES: To determine the effects of age and heart rate on blood flow velocities and durations of cardiac events obtained by PW Doppler echocardiography in healthy, nonsedated cats. ANIMALS: A convenience sample of 87 healthy, nonsedated cats aged 3 months to 19 years. METHODS: Prospective, observational study. PW Doppler measurements were obtained by echocardiography. Association of age and heart rate with PW Doppler values was evaluated by simple and multiple linear regressions and ANCOVA. RESULTS: Significant weak positive relationships were found between age and isovolumic relaxation time (IVRT) (R2= 0.18; P< or = .001), and between age and duration of pulmonary venous retrograde flow (R2= 0.07; P= .041). There was a significant weak negative relationship between age and transmitral peak early diastolic velocity (R2= 0.19; P< or = .001). Age and heart rate were significantly related to pulmonary venous peak systolic velocity (R2= 0.13; P= .008). Heart rate affected transmitral peak late diastolic velocity (R2= 0.11; P= .006). After adjusting for heart rate effect, the PW Doppler variables that were significantly different between age groups were transmitral peak early diastolic velocity (P< or = .001), duration of transmitral late diastolic flow (P< or = .001), IVRT (P< or = .001), and the ratio of duration of transmitral late diastolic flow to duration of pulmonary venous retrograde flow (P= .029). CONCLUSIONS AND CLINICAL IMPORTANCE: The association of several PW Doppler-derived variables and age and heart rate is weak and not clinically important.     

Microdose computed tomographic cardiac angiography in normal cats

ObjectivesTo determine if microdose contrast-enhanced multi-detector computed tomographic angiography (MDCTA) allows characterization of cardiac chambers in lightly sedated normal cats.AnimalsSeven healthy domestic cats.MethodsLightly sedated normal cats were imaged pre-contrast and with microdose (0.22 ml/kg of non-ionic iodinated contrast medium, 300 mg I/ml) triple-phase MDCTA in a motion restriction device.ResultsOn pre-contrast images, the aorta (median: 52.43 Hounsfield units [HU], range 27.35–76.74 HU) was outlined by significantly (p = 0.015) lower attenuating periaortic fat (−66.16 HU, −42.62 to −92.77 HU). On post-contrast images, median peak contrast enhancement in the right ventricle (111.77 HU, 36.09–141.60 HU) was achieved in 3.1 s (range 2.9–7.3 s), in the aorta (149.30 HU, 99.43–319.60 HU) and left atrium (180.83 HU, 88.53–266.84 HU) in 6.4 s (range 5.6–7.7 s) and in the left ventricle (147.89 HU, 57.23–245.77 HU) in 7.10 s (range 6.2–11.2 s). Significantly higher attenuation was measured between all chambers and walls, the right ventricular lumen and interventricular septum (median ratio 53.78 HU, range 0.21–83.20 HU), left ventricular lumen and left ventricular free wall (89.32 HU, 38.81–185.95 HU) and aorta and periaortic fat (190.43 HU, 143.22–425.44 HU) on post-contrast images.ConclusionsSufficient biological contrast is available on survey CT to discriminate between the aorta and the left atrium, and microdose MDCTA provides sufficient contrast enhancement for adequate visualization of the heart chambers in normal cats.     

Peak mean myocardial velocities and velocity gradients measured by color M-mode tissue Doppler imaging in healthy cats

We sought to assess the feasibility of recording the myocardial velocity gradients (MVGs) and mean myocardial velocities (MMVs) measured by color M-mode tissue Doppler imaging (TDI) in the free wall of unsedated normal cats (n = 18) with a 7.4-MHz probe equipped to record TDI images. The peak MVG and MMV values during the different phases of the cardiac cycle corresponded to certain color velocity patterns occurring in the left ventricular free wall (LVFW). Biphasic shifts were recorded in the tracings of both the MVG and MMV during early diastole (E1 and E2) as well as during the isovolumic relaxation (IVR) and isovolumic contraction (IVC) phases. Stepwise regression analysis showed that age was the only significant predictor for the peak MVG values during the 2nd phase of early diastole (E2) (r = -0.79, r2 = 0.63, and P < .001). The peak late diastolic MVG values were associated positively with age (r = 0.50, r2 = 0.25, and P < .05). The peak MMV values showed a negative association with age during E2 (r = -0.71, r2 = 0.50, and P < .001) as well as during early systole (Se) (r = -0.55, r2 = 0.30, and P < .05) and late systole (SI) (r = -0.62, r2 = 0.39, and P < .01). A positive association was found between age and the peak MMV values during late diastole (r = 0.54, r2 =- 0.29, and P < .05). The MVG values showed cyclic variations consistent with wall thickness changes. The accuracy of velocity determination and the spatial resolution of the system used were validated with a phantom. To our knowledge, this study is the 1st report of the application of this technique to the myocardium of cats,providing insights into the physiology of myocardial motion. It provides reference ranges of the peak MVG and MMV values for future studies of feline myocardial diseases.     

Color and power Doppler ultrasonography for characterization of splenic masses in dogs

Benign and malignant splenic masses can appear similar on B-mode imaging, making ultrasound sensitive but not specific in their diagnosis. Our goal was to characterize color and/or power Doppler characteristics of vasculature within and adjacent to a splenic mass, which would distinguish benign vs. malignant lesions. The hypothesis was that malignant splenic masses will have altered vascular patterns compared with benign masses. Color and power Doppler cineloops evaluating the vasculature within the mass and normal splenic parenchyma were obtained in sagittal and transverse planes using a standardized protocol. Categories of evaluation included presence of peritoneal effusion, a large aberrant or tortuous vessel within the mass, relative blood flow within the mass compared with normal parenchyma, and path of vessels in the adjacent parenchyma entering into the mass. All patients had histopathologic or definitive cytologic diagnosis. Thirty-one dogs were included. There were 13 malignant masses and 18 were benign. Peritoneal effusion was significantly associated with malignancy (P = 0.0007). Presence of an aberrant or tortuous vessel within the mass was nearly significant (P = 0.059). There was no significant difference in any of the color or power Doppler blood flow evaluations. Ultrasonographic findings of a splenic mass and peritoneal effusion may indicate malignancy. The presence of an aberrant vessel within a splenic mass could suggest malignancy; however more data are needed.     

Safety of masitinib mesylate in healthy cats

Background: Masitinib mesylate is a PO‐administered tyrosine kinase inhibitor developed both for human and animal diseases with activity against both mutated and wild type forms of the c‐kit receptor and platelet‐derived growth factor receptors α and β, and is currently registered in Europe for the treatment of mast cell tumors in dogs. Hypothesis/Objectives: The objective of this study was to determine if healthy cats can tolerate administration of masitinib without clinically relevant adverse effects. Animals: Twenty healthy research colony‐specific pathogen‐free cats. Methods: This study was a prospective, randomized phase 1 clinical trial. Masitinib was administered PO to 20 healthy cats. Ten cats received 50 mg masitinib every other day for 4 weeks, and 10 cats received 50 mg masitinib daily for 4 weeks. Results: Clinically relevant proteinuria was noted in 2/20 (10%) cats (both treated daily), and neutropenia was noted in 3/20 (15%) (seen in both treatment groups). An increase in serum creatinine concentration and adverse gastrointestinal effects were noted in some cats. Conclusions and Clinical Importance: Masitinib mesylate was tolerated in the majority of cats. Long‐term administration and pharmacokinetic studies are needed to further assess the use of masitinib in cats.     

Anticoagulant effects of low-molecular-weight heparins in healthy cats

BACKGROUND: Low-molecular-weight heparin (LMWH) has potential benefit in cats at risk for thromboembolic disease. However, LMWH pharmacokinetics has not been characterized in the cat. Drug effect with LMWH may be evaluated with analysis of factor Xa inhibition (anti-Xa) or thromboelastography (TEG). HYPOTHESIS: Administration of LMWH at previously recommended dosages and schedules to healthy cats will result in inhibition of factor Xa and hypocoagulable TEG. ANIMALS: In vivo research with heparin was performed in 5 purpose-bred cats. METHODS: In a prospective study with randomized crossover design, heparin or placebo was administered. Treatments were unfractionated heparin (UFH), 250 IU/kg q6h; dalteparin, 100 IU/kg q12h; enoxaparin, 1 mg/kg q12h; or 0.9% saline, 0.25 mL/kg q6h. Each drug was administered for 5 consecutive days followed by a minimum washout of 14 days. Baseline and post-treatment analyses included anti-Xa, TEG, and prothrombin time/activated partial thromboplastin time. RESULTS: Mean anti-Xa activity 4 hours after enoxaparin (0.48 U/mL) approached the human therapeutic target (0.5-1.0 U/mL); however, mean trough anti-Xa activity was below detection limits. Mean anti-Xa activity 4 hours after dalteparin was lower, and only 1 cat attained therapeutic target at a single time point. Cats receiving UFH attained target anti-Xa activity and changes in TEG at trough and 4 hours. CONCLUSIONS: Cats have rapid absorption and elimination kinetics with LMWH therapy. On the basis of pharmacokinetic modeling, cats will require higher dosages and more frequent administration of LMWH to achieve human therapeutic anti-factor Xa activity of 0.5-1 U/mL. Peak anti-Xa activity is predicted at 2 hours after administration of LMWH.     

Pulsed tissue Doppler imaging in normal cats and cats with hypertrophic cardiomyopathy

Myocardial motion was quantified in normal cats (n = 25) and cats with hypertrophic cardiomyopathy (HCM) (n = 23) using the pulsed tissue Doppler imaging (TDI) technique. A physiologic nonuniformity was documented in the myocardial motion of normal cats, which was detected as higher early diastolic velocities, acceleration, and deceleration in the interventricular septum compared with the left ventricular free wall (LVFW). HCM cats exhibited lower early diastolic velocities, acceleration, and deceleration and also prolonged isovolumic relaxation time compared with normal cats. These differences were detected mainly along the longitudinal axis of the heart. A cutoff value of E' in the LVFW along the longitudinal axis >7.2 cm/s discriminated normal from HCM cats with a sensitivity of 92% and a specificity of 87%. The physiologic nonuniformity of myocardial motion during diastole was lost in affected cats. Systolic impairment (decreased late-systolic velocities in most segments along the longitudinal axis and decreased early systolic acceleration in both mitral annular sites) was evident in HCM cats irrespective of the presence of left ventricular outflow tract obstruction and congestive heart failure. Postsystolic thickening was recorded in the LVFW along the longitudinal axis only in affected cats (n = 6) and was another finding indicative of systolic impairment in the HCM of this species. This study identified both diastolic and systolic impairment in cats with HCM compared with normal cats. The study also documents the normal physiologic nonhomogeneity in myocardial motion in cats and the subsequent loss of this feature in the HCM diseased state.     

Serum alhpa 1-acid glycoprotein concentrations in healthy and tumor-bearing cats

The purpose of this study was to evaluate alpha 1-acid glycoprotein (AGP) concentrations in tumor-bearing and healthy cats. The hypothesis of the present study was that AGP concentrations would be significantly increased in tumor-bearing cats. Serum from 51 healthy and 97 tumor-bearing, client-owned cats was harvested at the time of presentation and stored at -80 degrees C until assayed. Cats with measurable, histologically confirmed malignancies, and healthy cats of similar ages were included. Serum was assayed for AGP concentration by using a radial immunodiffusion method. AGP concentrations were significantly (P = .0051) higher in tumor-bearing (763 +/- 595 microg/mL; mean +/- SD) when compared to healthy cats (501 +/- 377 microg/mL; mean +/- SD). Of the tumor-bearing cats, 35 had carcinomas, 33 had sarcomas, and 26 had discrete, round cell tumors. AGP concentrations were 645 +/- 62 microg/mL, 660 +/- 540 microg/mL, and 967 +/- 860 microg/mL, respectively, and there were no significant differences among the groups.     

Hyperglycaemia but not hyperlipidaemia decreases serum amylase and increases neutrophils in the exocrine pancreas of cats

The goal of the study was to determine whether hyperglycaemia or hyperlipidaemia causes pancreatitis in cats and to assess the effect of excess serum glucose and lipids on amylase and lipase activity. Ten-day hyperglycaemic and hyperlipidaemic clamps were carried out in five and six healthy cats, respectively. Ten healthy cats received saline and served as controls. The activity of amylase was below the normal range in 4 of 5 hyperglycaemic cats by day 10. The activity of lipase did not vary in any of the cats. Samples of exocrine pancreas were normal on histological examination, but the number of tissue neutrophils was increased in hyperglycaemic cats (P < 0.05). In a retrospective study 14 of 40 (35%) cats with naturally occurring diabetes mellitus had amylase activities below the reference range at the time of admission. Amylase activities normalised within 1 week of insulin therapy and subsequent glycaemic control. Lipase activity was increased in 26 of 40 (65%) diabetic cats and remained elevated despite glycaemic control. In conclusion, hyperglycaemia, but not hyperlipidaemia, increases pancreatic neutrophils in cats. However, because the histological morphology of the exocrine pancreas was normal, hyperglycaemia may play only a minor role in the pathogenesis of pancreatitis. Low amylase activities in diabetic cats may reflect an imbalance in glucose metabolism rather than pancreatitis.     

The GLP-1 mimetic exenatide potentiates insulin secretion in healthy cats

The glucagon-like peptide-1 mimetic exenatide has a glucose-dependent insulinotropic effect, and it is effective in controlling blood glucose (BG) with minimal side effects in people with type 2 diabetes. Exenatide also delays gastric emptying, increases satiety, and improves β-cell function. We studied the effect of exenatide on insulin secretion during euglycemia and hyperglycemia in cats. Nine young, healthy, neutered, purpose-bred cats were used in a randomized, cross-over design. BG concentrations during an oral glucose tolerance test were determined in these cats previously. Two isoglycemic glucose clamps (mimicking the BG concentration during the oral glucose tolerance test) were performed in each cat on separate days, one without prior treatment (IGC) and the second with exenatide (1 μg/kg) injected subcutaneously 2 h before (ExIGC). BG, insulin, and exenatide concentrations were measured, and glucose infusion rates were recorded and compared in paired tests between the two experiments. After exenatide injection, insulin serum concentrations increased significantly (2.4-fold; range 1.0- to 9.2-fold; P = 0.004) within 15 min. This was followed by a mild decrease in BG concentration and a return of insulin concentration to baseline despite a continuous increase in serum exenatide concentrations. Insulin area under the curve (AUC) during ExIGC was significantly higher than insulin AUC during IGC (AUC ratio, 2.0 ± 0.4; P = 0.03). Total glucose infused was not significantly different between IGC and ExIGC. Exenatide was detectable in plasma at 15 min after injection. The mean exenatide concentration peaked at 45 min and then returned to baseline by 75 min. Exenatide was still detectable in the serum of three of five cats 8 h after injection. No adverse reactions to exenatide were observed. In conclusion, exenatide affects insulin secretion in cats in a glucose-dependent manner, similar to its effect in other species. Although this effect was not accompanied by a greater ability to dispose of an intravenous glucose infusion, other potentially beneficial effects of exenatide on pancreatic β cells, mainly increasing their proliferation and survival, should be investigated in cats.     

Evaluation of Doppler ultrasonography for the measurement of blood flow in young loggerhead sea turtles (Caretta caretta)

The aim of this study was to identify ultrasound accessible blood vessels in the loggerhead sea turtle (Caretta caretta) and describe their Doppler waveform patterns, peak systolic velocity, mean velocity, systolic/diastolic ratio as well as pulsatility and resistive indices. B-mode, colour and pulsed-wave Doppler examinations were performed on 10 turtles. Flow measurements were recorded for the left and right aorta, epigastric and internal iliac arteries, and right hepatic vein. Additionally, the large blood vessels of three dead turtles were injected with latex and dissected for anatomical support. A parabolic flow velocity profile was observed in all arteries. The waveforms of the right and left aortic arteries showed an unusual pattern when compared with mammals. The hepatic vein flow velocity waveform of the loggerhead sea turtle was found to be similar to that in the dog, although the flow velocity in the C-wave was higher than that in the A-wave. The low resistance flow pattern observed suggests that the loggerhead sea turtle's organs require a continuous blood supply.     

Percutaneous ultrasound-guided cholecystocentesis in healthy cats

Percutaneous ultrasound-guided cholecystocentesis (PUC) is a minimally invasive technique for bile collection that is used successfully in human patients with cholecystitis. Its use in veterinary medicine for evaluation of hepatobiliary disorders has been limited because of the perceived unacceptable risk of bile peritonitis. An experimental study was conducted to evaluate the safety and efficacy of PUC, to collect data on bile cytology and bacteriologic culture, and to attempt to isolate Helicobacter spp. from the bile of healthy cats. In fasted and sedated cats, PUC was performed with a 22-gauge 1.5-in. (3.81 cm) needle with an attached 12-mL syringe via a right-sided transhepatic approach (n = 1) or into the fundus of the gallbladder (n = 11) via a right ventral abdominal approach. An attempt was made to completely empty the gallbladder. A small amount of abdominal effusion, consistent with bile or blood, was seen ultrasonographically immediately after aspiration in the 1st cat. Ultrasonographic complications with the 2nd technique were not observed in the remaining 11 cats. Decreased appetite and evidence of mild abdominal pain were detected in 4 cats within 2 days after PUC. The mean neutrophil count increased 2 days after PUC (P < .01) but remained within the reference range. The bile was acellular in 11 of 12 cats, and aerobic, anaerobic, and Helicobacter spp. cultures yielded no growth in 12 of 12 cats. There were no remarkable gross or histologic lesions of abdominal organs at the postmortem examination (8 cats) performed 7-8 days after the procedure. PUC appears to be a safe and technically simple procedure. Further studies are warranted to determine the use and safety of PUC in cats with hepatobiliary diseases.     

Contrast-enhanced ultrasonography in the differentiation of retinal detachment and vitreous membrane in dogs and cats

Objectives : To evaluate contrast‐enhanced ultrasonography (CEU) and colour Doppler imaging (CDI) for detection of persistent vascularisation in retinal detachment. Methods : In 22 eyes, retinal detachment (n=13) and vitreous membranes (n=9) were confirmed by ophthalmological examination, during cataract surgery, by histopathology or after vitreoretinal surgery. Tentative diagnosis of retinal detachment or vitreous membrane was made using grey‐scale B‐mode ultrasonography. Assessment of retinal detachment was based on the presence or absence of vascularisation in the membranous structure using CDI and CEU. Results : Sensitivity, specificity, positive‐predictive value and negative‐predictive value of grey‐scale ultrasonography in differentiating retinal detachment from vitreous membrane were 92·3%, 66·6%, 80% and 85·7%. In 91% of eyes, colour Doppler assessment was unsuccessful due to the movement of the eye. Persistent vascularisation was demonstrated in all cases of retinal detachments with CEU. CEU was 100% accurate for detection and differentiation between retinal detachment and vitreous membrane. Clinical Significance : CEU is a useful clinical tool for the diagnosis of retinal detachment and vitreous membrane in dogs and cats.     

Circulating natriuretic peptides in cats with heart disease

BACKGROUND: Circulating natriuretic peptide concentrations are increased in cats with myocardial dysfunction. HYPOTHESIS: Serum N-terminal fragment of proatrial natriuretic peptide (NT-proANP) and NT-probrain natriuretic peptide (proBNP) concentrations may predict the presence of heart disease (HD) and congestive heart failure (CHF). A positive relationship is also predicted among natriuretic peptide (NP) concentrations, a noninvasive estimate of left ventricular filling pressure (E/E(a)), and an echocardiographic measure of left atrial (LA) size (LA/aortic diameter [Ao]). METHODS: Serum NP concentrations were measured in 28 healthy control and 50 study cats using sandwich enzyme immunoassays. The study group comprised cats, with HD but no CHF (HD - CHF, n = 17) and cats with CHF (HD + CHF, n = 33). The relationship among NP concentrations, LA size, and E/E(a) was examined. The ability of NP to distinguish control from study cats, and HD - CHF from HD + CHF cats, was explored using receiver operator curve analysis. RESULTS: NP concentrations were significantly lower in control than in study cats (P= .0001). The NT-proBNP concentrations were positively correlated with LA/Ao ratio (rho= 0.34; P= .02) and with E/E(a) ratio (rho= 0.68; P < .05). An NT-proBNP concentration of 49 fmol/mL gave a sensitivity and specificity of 100 and 89.3%, respectively, for correctly distinguishing 96.2% of control from study cats. Pairwise comparisons of the areas under the curve identified a statistically significant difference (P= .011) between NT-proANP and NT-proBNP to distinguish control from study cats. NT-proANP and NT-proBNP concentrations were significantly higher in HD + CHF cats than in HD - CHF cats (P= .0023 and .0001, respectively). CONCLUSIONS: Serum concentrations of NT-proANP and particularly NT-proBNP were different in healthy control cats, asymptomatic cats with HD, and cats with CHF, suggesting that measurement of NP concentrations may prove clinically useful as an initial screening test for cats with suspected cardiac disease.     

Triple phase computed tomography of the pancreas in healthy cats

While the availability and use of computed tomography (CT) continues to grow, no study has described the size and multiphase CT appearance of the normal feline pancreas. This information is important to not only allow more accurate identification and differentiation of disease, but it may also be useful in assessing pancreatic function. In this prospective analytical study, we described a triple phase CT protocol of the pancreas for use in sedated cats and the attenuation, enhancement pattern, size, and volume of the pancreas for a group of healthy cats. Fifteen healthy cats were enrolled in the study and a standardized protocol for acquiring arterial, portal, and delayed phase CT images of the pancreas was developed and described. The pancreas was hypo to isoattenuating to both the liver and spleen in all phases in the majority of cats with a homogenous enhancement pattern noted in all 15. Mean pancreatic attenuation was 48, 79, 166, and 126 Hounsfield units (HU) respectively on precontrast, arterial, portal, and delayed phase images. In addition, mean height, length, and width of the left lobe of the pancreas were larger than the right lobe in all 15 cats. There were no associations between volume and volume: body weight ratio with age (P = 0.6518, P = 0.6968) or sex (P = 0.7013, P = 0.2043). This baseline information may be beneficial for use in future studies characterizing pancreatic disease in cats as well as future research studies evaluating pancreatic endocrine function.     

Dietary NaCl does not affect blood pressure in healthy cats

The purpose of this study was to assess the effects of dietary salt intake on systolic blood pressure, water intake, urine output, and urine concentration in cats. Ten healthy young adult cats (mean age 2.5 years) were randomly divided into 2 groups and fed either a control diet (0.46% Na and 1.33% Cl on a dry matter [DM] basis) or a diet with a moderately increased salt content (1.02% Na and 2.02% Cl on a DM basis) for 2 weeks. After a 1-week wash-out period, each group was switched to the opposite diet for 2 weeks. During each 2-week study period, food and water intake, urine volume, urine specific gravity, and urine osmolality were measured daily. Systolic blood pressure (calculated as the mean of 5 readings measured with a Doppler flow detector) was assessed twice daily. No significant effect of diet composition was found on systolic blood pressure, and blood pressure measurements remained within reference limits throughout the study in all 10 cats. However, animals fed the higher salt diet had significantly increased water intake and urine osmolality, and significantly decreased urine specific gravity in comparison to animals fed the control diet. Examination of results of this preliminary study suggests that feeding a diet with moderately increased salt content increases water intake and causes diuresis without increasing systolic blood pressure in healthy adult young cats.     

Non-invasive assessment of left ventricular relaxation property using color M-mode-derived intraventricular pressure gradients in cats

IntroductionDiastolic dysfunction is an early clinical feature of feline hypertrophic cardiomyopathy (HCM). The left ventricular filling in early diastole is facilitated by the diastolic intraventricular pressure gradient (IVPG). The study objectives were to evaluate color Doppler M-mode-derived IVPG calculation in cats as a non-invasive assessment of the left ventricular relaxation property to determine the normal ranges of peak IVPG in cats and investigate the influence of left ventricular function and heart rate (HR).AnimalsOne hundred and six client-owned apparently healthy cats.MethodsProspective cross-sectional study. Quantitative analysis of color Doppler M-mode images was used to estimate total and segmental IVPGs non-invasively.ResultsThe total IVPG was 0.76 mmHg (95% reference interval (RI): 0.28–1.29 mmHg), the basal IVPG 0.34 mmHg (95% RI: 0.07–0.63 mmHg), and the mid-apical IVPG 0.42 mmHg (95% RI: 0.15–0.71 mmHg). Total and segmental IVPG increased with HR (P < 0.003), while segmental percent IVPG was HR independent. A short isovolumic relaxation time (IVRT) and a high mitral annular velocity in early diastole were associated with an increase in total IVPG (P = 0.008 and P = 0.009, respectively) adjusted for HR. An increase in IVPG was associated with an increase in mitral inflow velocity (P < 0.001).ConclusionsFeline IVPGs increase with HR and a short IVRT, which was believed to be a normal physiologic adrenergic response associated with an increased sympathetic tone. Future studies of segmental IVPG changes in feline HCM are needed to evaluate the clinical applicability of color Doppler M-mode estimated IVPGs in feline cardiology.