Veterinary Research Forum

Abstract Ventricular septal defect (VSD) is a common congenital anomaly in large animals, but it is rarely documented in small ruminants. This report described a case involving a three-month-old male lamb of the Iranian Shall breed that was presented to a Veterinary Hospital of University of Tehran with nasal discharge and growth retardation. Clinical examination revealed a heart rate of 120 beats per min, a respiratory rate of 50 breaths per min, pale mucous membranes and a low-grade pansystolic murmur that was auscultated bilaterally in the thoracic region. Echocardio-graphy revealed a 10.00 mm defect between the right and left ventricles, located in the supraventricular region behind the aortic valve, along with evidence of left-to-right shunting. Imaging studies including echocardiography and radiography indicated increased cardiac volume particularly in the right ventricle. These findings were corroborated by necropsy. This case study aimed to elucidate the imaging findings associated with Ventricular septal defect in an Iranian Shall lamb.

Abstract Echocardiography is a noninvasive, highly sensitive method for evaluating heart disease in veterinary medicine, crucial for measuring cardiac structures and functions. Despite its importance, limited data exist on sheep, particularly the Ghezel breed, a significant breed in Iran. This study aimed to establish normal echocardiographic values for Ghezel sheep, providing reference data for both clinical and research applications. We evaluated 15 healthy Ghezel sheep with a mean age of 16.50 ± 1.80 months and a mean weight of 42.69 ± 4.73 kg. Comprehensive clinical exams, biochemical and hematological tests and color Doppler echocardiography were performed. Descriptive results from standard right and left parasternal views in both longitudinal and transverse planes were obtained and compared to existing studies. The study successfully established pulse wave Doppler reference values for the Ghezel breed. These findings could be used in diagnosing heart disease in Ghezel sheep and would be beneficial in future research particularly in sheep used as an animal model for translation in human cardiac studies.

Abstract Cardiovascular and respiratory alterations during anesthesia are of major concern in canines. Thus, it is essential to understand the potential depressant effects of anesthetic drugs on cardio-vascular system; so that, anesthetic procedures are conducted in the best possible way. The objective of the study was to assess and compare the echocardiographic indices during dex-medetomidine and midazolam anesthesia in dogs undergoing elective ovariohysterectomy. Twenty-eight female dogs brought to the department for elective ovariohysterectomy were randomly divided into two groups comprising of 14 each. Sedation was achieved with dex-medetomidine and G_MID. Physiological parameters and echocardiographic indices were evaluated before drug administration (T₀), after 10 min of sedation (T₁), after induction (T₂) and at the end of surgery (T₃) in both groups. Heart rate was significantly higher at T₁, T₂ and T₃; while, rectal temperature was significantly lower at T₃ in G_MID compared to the G_DEX. There was a significant decrease in stroke volume and cardiac output values at T₁ and then, a significant increase at T₂; whereas, there was a non-significant decrease at T₃ in both groups. Ejection fraction and fractional shortening values decreased significantly at T₁, increased significantly at T₂ and then, decreased significantly at the end of surgery (T₃). Dexmedetomidine-ketamine and midazolam-ketamine combinations provide better hemodynamic and respiratory stability in the dogs undergoing elective ovariohysterectomy. Systolic functions were minimally altered with G_MID compared to G_DEX. Thus, G_MID is more cardio stable compared to G_DEX.

Abstract Echocardiography is a non-invasive and gold standard imaging tool for diagnosing dilated cardiomyopathy (DCM) in dogs. This study aimed to compare the echocardiographic parameters between healthy and DCM-affected dogs. A total of 52 client-owned dogs, comprising 38 males and 14 females, were included. Among these, 24 dogs (46.15%) were classified as healthy controls and 28 dogs (53.85%) were part of DCM group. On breed-wise prevalence, it was reported that Labrador Retriever breeds showed a higher incidence of DCM than the others. The comparative studies of echocardiographic parameters showed that DCM-affected dogs had significantly higher values in left ventricular long axis length at -end diastole (LVLdA4C) and -end systole (LVLsA4C), end diastolic volume (EDV), end systolic volume (ESV), left atrium (LA)/aorta diameter (Ao) ratio, left ventricular internal dimension at systole (LVIDs), and end point septal separation (EPSS), as well as significantly lower values in left ventricular contractibility indices such as fractional shortening (FS) and ejection fraction (EF) compared to healthy dogs. Also, receiver operating characteristic curves were made to determine the optimal cut-off points for each echocardiographic parameter with specificity and sensitivity for diagnosing DCM. Significant areas under the curve were observed for parameters such as LVIDs, EF, FS, LA/Ao, EPSS, LVLdA4C, LVLsA4C, left ventricular EDV, left ventricular ESV, and ESV for DCM-affected dogs. This cut-off value can be used as an early diagnosis of DCM through echocardiography, facilitating timely clinical interventions and management strategies for improved quality of life in dogs.

Abstract The aim of this study was to compare the sedative and cardiovascular effects of the combination of xylazine-acepromazine versus xylazine-pregabalin - in horses. Four healthy crossbred horses were included in the study and assigned to two treatments. In treatment I (T1), the animals received xylazine hydrochloride (1.00 mg kg^-1) in combination with acepromazine maleate (0.05 mg kg^-1) intravenously. In treatment II (T2), the animals received intragastric administration of pregabalin (4.00 mg kg^-1) followed by xylazine hydrochloride (1.00 mg kg^-1) intravenously after 60 min. Head height above ground (HHAG) and echocardiographic indices were evaluated. In T1, recordings were made 5 minubefore and 5, 15, 30, 60, and 90 minu after drug administration. In T2, recordings were made 5 min before pregabalin, 55 minu after pregabalin administration, and then 5, 15, 30, 60, and 90 min after xylazine hydrochloride acepromazine injection. Analyses of the data showed there were no significant differences regarding HHAG and echocardiographic indices between the two treatments. Intragastric administration of pregabalin prior to xylazine could be considered as an alternative premedication regimen when acepromazine administration is contraindicated or undesirable.

Abstract The aim of this study was to compare the sedative and cardiovascular effects of the combination of acepromazine-clonidine versus acepromazine-xylazine in horses. Four healthy cross-bred horses were included in the study. They were assigned to two treatments. In treatment I (T1), the animals received xylazine hydrochloride (1.00 mg kg^-1) in combination with acepromazine maleate (0.05 mg kg^-1) intravenously (IV). In treatment II (T2), the animals received intra-gastric administration of clonidine (0.002 mg kg^-1) followed by acepromazine (0.05 mg kg^-1; IV) after 60 min. Head height above the ground (HHAG) and echocardiographic indices were evaluated. In T1, recordings were made 5 min before and 5, 15, 30, 60, and 90 min after drug administration. In T2, recordings were made 5 min before clonidine, 55 min after clonidine administration, and then 5, 15, 30, 60, and 90 min after acepromazine injection. Analyses of the data showed there were not significant differences regarding HHAG and echo-cardiographic indices between two treatments. For sedation of healthy horses, it was concluded that intra-gastric administration of clonidine and IV administration of acepromazine showed similar sedative and cardiovascular effects compared to IV acepromazine-xylazine administration.

Abstract Ovariohysterectomy (OHE) is one of the most common surgeries in veterinary medicine. Although this surgical method has several advantages, it can alter the function of various organs such as heart. The present study investigated the effect of OHE on cardiac functions using M-mode echocardiography. A total of 10 healthy adult domestic short-haired cats were enrolled in the current study. Fractional shortening (FS) and ejection fraction (EF) percentages along with cardiac output (CO) were measured through the right parasternal approach in papillary muscle level view. Moreover, the levels of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) were measured by enzyme-linked immunosorbent assay before OHE (D0) as well as 10 (D10), 20 (D20) and 30 (D30) days after OHE. The results of this study showed that the mean FS and EF decreased on all days of the study. The FS reduction was significant between D10 and D30 and EF changes were significant between D10 and D20. The means of CO increased significantly on D0 compared to the D10. After D20, CO reduced until the end of the study. Mean concentrations of LH and FSH increased on all research days; but, the changes were significant until D20. Despite the negative effects of OHE on myocardial function, there was no significant correlation between hormonal levels and echocardiographic findings after OHE in this study.

Abstract Right ventricular structural and functional changes result from many cardiovascular disorders in cats. Accordingly, echocardiographic evaluation of the size and function of the right ventricle (RV) provides important prognostic information in many conditions affecting the right heart. Therefore, detection of these changes is clinically important and needs reference values to ease the diagnosis. The present study was designed to calculate structural and fanctional right ventricular variables in 10 apparently healthy cats (six males and four females, averege age 1 year old and body weight 2.70 - 4.80 kg) with no sedation. For this purpose, The minimum, maximum, mean ± standard error of the mean of right ventricle internal dimention in systole and diatole (cm), right ventricle free wall thickness in systole and diastole (cm), fractional shortening (%), right ventricle volume in systole and diastole (mL), right ventricle area in systole and diastole (cm²), ejection fraction (%) and fractional area change (%) were measured and reported. Descriptive statistics were provided for all calculated variables. Statistical correlation of the collected variables with body weight, gender and heart rate were analyzed. Results showed that there is a significant correlation between heart rate with body weight and between systolic and diastolic RV volumes with gender. The results of the present study would help clinicians in the diagnosis of the right heart changes in DSH cats.

Abstract Right ventricular parameters change in many cardiovascular diseases; so, the presence of normal right ventricular parameters is necessary to diagnose these diseases. Ten clinically healthy adult domestic short-haired cats including six males and four females in the range of 2.70 to 4.80 kg were studied using echocardiography without sedation. The speed and pressure of blood flow through the tricuspid and pulmonary valves, speed of the movement of tricuspid valve and tricuspid annular plane systolic excursion (TAPSE) were recorded using conventional pulsed-wave (PW) Doppler, tissue Doppler imaging (TDI) and M-mode, respectively. No significant statistical differences were observed between the measured values and sex, heart rate and body weight. A positive correlation was observed between the maximum velocity of the right ventricular outflow tract and heart rate and also between TAPSE slope and body weight. With determining the normal values of PW-TDI of the right ventricle in apparently healthy domestic short-haired cats, it is expected that with providing normal reference values, the diagnosis of heart diseases especially asymptomatic heart disease be achieved as soon as possible to provide the best appropriate therapeutic management and monitoring decision about them.

Abstract Heart murmurs and valvular regurgitation are common in horses and often have no effect on their performance. However, when structural changes occur in the heart size, they can affect performance adversely. This study aimed to examine the correlation between cardiac valves disease and poor performance in athletic horses. A total of 300 athletic Thoroughbred and mix-breed horses including 164 Mares and 136 Stallions, with a history of poor performance, were selected. Horses with cardiac murmurs were identified and further cardiac examination including precise auscultation, base-apex electrocardiogram for possible dysrhythmias at rest and after exercise, echocardiographic and hematological tests were conducted in two stages. The first was at admission time and the second examination was done four to six months later to evaluate the outcome of the possible disorders. Respiratory system and musculoskeletal diseases were diagnosed respectively in 93 and 149 out of 300 examined horses and 36 horses showed heart murmur without any other complications. Echocardiography was performed in horses with heart murmur and 25 of them showed regurgitation of the cardiac valve. During the first examination, 7 horses were diagnosed with regurgitation and changes in the size of cardiac chambers, whereas this number increased to 25 during the second examination. There was no significant relationship between degree of murmur and severity of regurgitant jet in horses. The valvular regurgitation can affect the performance when causing changes in the size of the cardiac chambers which can consequently jeopardize the athletic future of the horse.

Abstract Echocardiography illustrates a convenient and noninvasive tool for measuring cardiac output (CO) changes after administration of sedative drugs, but it is unknown in camelids practice. The aim of present study was to investigate echocardiographic effects of intravenous (IV) injection of medetomidine and xylazine in camel calves. Twenty apparently healthy immature male one-humped camel calves (Camelus dromedarious) were divided into four groups (five animals in each treatment). Medetomidine and xylazine were injected into the left jugular vein at two different doses of 10.00 and 20.00 μg kg^-1 and 0.20 and 0.40 mg kg^-1, respectively. Effects on some selected echocardiographic parameters were recorded at different intervals, before drug administrations (baseline) and after 3, 60 and 120 min. Data were analyzed by repeated measure, ANOVA test, then relevance and significance were taken as p ≤ 0.05. Significant decrease in fractional shortening percentage (FS%), ejection fraction percentage (EF%), stroke volume (SV), heart rate (HR) and subsequent CO were noticeable 3 min after drug administration in medetomidine high dose (MH), medetomidine low dose (ML) and xylazine high dose (XH) groups (p ≤ 0.05), furthermore at this time significant decrease in left ventricular mass (LVmass) and left ventricular systolic time intervals were seen in these groups, however, in xylazine low dose (XL) group, the lowest level of most echocardiographic parameters were detectable after 60 min. High dose IV injection of medetomidine was associated with significant decrease in most echocardiographic parameters without echocardiographic arrhythmia. Although, ML and XH groups had the same effects on echocardiographic indices but the intensity and duration were less than MH group.

Abstract Echocardiography is a non-invasive method of cardiac evaluation in most species. Echocardiographic reference parameters are poorly documented in sheep and not documented in Ghezel sheep. The purpose of this study was to determine reference ranges of normal echocardiographic parameters using two-dimensional and M-mode techniques in Ghezel sheep. In 15 healthy female Ghezel sheep aged between 15 and 18 months, echocardiography was performed in standing position from left and right parasternal approach focused at 3^rd - 5^th intercostal spaces using a 2.50 - 5.00 MHz phased array transducer. The following parameters were measured in two-dimensional echocardiography: left atrial diameter (LAD), mitral valve annulus (MVA), aortic sinus (AoS), aortic valve (AoV), pulmonary sinus (PuS), and pulmonary valve (PuV); and in M-mode echocardiography: interventricular septum (IVS), left ventricular internal diameter (LVID), left ventricular free wall (LVFW), right ventricle free wall (RVFW), right ventricle internal diameter (RVID). Calculated variables included the ratios LAD/Ao and Pu/AoS, and the fractional shortening (FS), end diastolic volume (EDV), end systolic volume (ESV), ejection fraction (EF), stroke volume (SV) and cardiac output (CO) of the left ventricle. In conclusion, echocardiographic parameters could be reliably assessed in Ghezel sheep and our study provided some normal echocardiographic reference ranges that might be useful in proper identification, visualization, and measurements of cardiac structures. Such findings could be useful to assess and to diagnose the specific heart diseases in sheep practice and also for experimental studies in sheep as an animal model used for research purposes in cardiovascular studies of human.

Abstract Patent ductus arteriosus (PDA) is a persistent patency of a vessel normally present in the fetus that connects the pulmonary arterial system to the aorta. The ductus arteriosus fails to close at birth when breathing commences and placental blood circulation is removed. Closure of the ductus arteriosus arises in response to decline pulmonary vascular resistance and increased systemic vascular resistance. This report describes a case of PDA in a two-month-old male lamb with clinical signs of machinery murmur, tachycardia, increase respiratory rate, weakness and ill thrift. Echocardiographic examination and necropsy finding confirmed PDA.