Age, Sex and Body Weight Related Echocardiographic Parameters of Clinically Healthy New Zealand White Rabbits

Omer Gurkan Dilek, Hasan Erden


Background: Echocardiography provides useful additional information on cardiac dimensions including heart wall and dimension of the ventricles, atria and conditions. Rabbits have been diagnosed with cardiac diseases, and an understanding of the animals’ cardiac chamber dimensions is vital in assessing the diseases’ severity and prognoses. Changes in cardiac dimensions due to age related and body weight were determined at different animals. The increased incidence of congenital cardiovascular anomalies makes it essential to establish the diagnosis at an early age. The aims of this study 1) establish normal values for the commonly used two-dimensional (2D) M-mode parameters using pre anaesthetics and 2) evaluate the effects of age, sex, and body weight on echocardiographic parameters in clinically healthy New Zealand rabbits.

Materials, Methods & Results: In this study we used 49 New Zealand white rabbits (25 male, 24 female) all reared under the same conditions. A general physical and clinical examination including complete blood count was performed for each animal. Body surface area was calculated as BSA= 0.00718 × Height 0.725 × Weight 0.425. Rabbits were sedated with midazolam before echocardiographic examination was performed. Echocardiographic examination was performed using a DC 6-Vet® (Mindray, PRC) ultrasonographic device equipped with a micro-convex 8 MHz probe. Right parasternal short-axis view, B-mode and two-dimensional guided M-mode parameters were measured. Echocardiographic measurements were performed using leading-edge-to-leading-edge conventions outlined by the American Society of Echocardiography. Statistical analyses were employed using the SPSS 19.0 program. Sex had no significant effect on the measured echocardiographic parameters except in the case of interventricular septum thickness in diastole values of the three-month-old rabbits. The increase in the left ventricular systolic and diastolic diameters, E- point to septal separation, diastolic aortic root parameters for the three, six, and nine-month-old groups indicated persistent anatomic heart enlargement. However, it was also discovered that the fractional shortening percentage of the left ventricle and diastolic diameters of left atrium:aortic root  were unrelated to age and weight.

Discussion: New Zealand rabbits are an important model for cardiovascular research, mainly as they are small and relatively inexpensive however large enough to allow anatomical and physiological experiments. Different ages and sizes of New Zealand rabbits showed no significant difference in fractional shortening despite heart enlargement. The ejection fraciton, which can be calculated from the left ventricular dimensions via M-mode echocardiography, is another parameter of cardiac function. Our echocardiograph calculated the ejection fraction automatically using the Teicholz formula. It was further observed that three-month-old rabbits ejection fraction of the left ventricle was higher than that of the six and nine-month-old rabbits. This might indicate the necessity of periodical analysis of echocardiographic parameters. Transthoracic echocardiography can be considered an applicable method for cardiovascular research using a growing rabbit animal model after appropriate adjustments for age, sex and body size. These findings give a better understanding of the functional changes investigated by echocardiography in rabbits and will be helpful when evaluating echocardiographic data in small experimental animals.

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Al-Haidar A., Farnir F., Deleuze S, Sandersen C.F., Leroux A.A., Borde L., Cerri S. & Amory H. 2013. Effect of breed, sex, age and body weight on echocardographic measurements in the equine species. Research in Veterinary Science. 95: 255-260.

Bhasin V., Shastry V.R.B., Singh D., Gulyani R., Malhi R.S., Kishore K., Singh R.N., Lahri S.S., Rai R.B. & Das P.K. 1989. Performance of broiler rabbits in a subtemperate Himalayan region. Journal of Applied Rabbit Research. 12: 263-265.

Boon J. 2011. The two dimensional echocardiographic exam. In: Boon J. (Ed). Veterinary Echocardiography. Chichester: Jon Willey & Sons, pp.53-138.

Boluyt M.O., Converso K., Hwang H.S., Mikkor A. & Russell M.W. 2004. Echocardiographic assesment of age-associated changes in systolic and diastolic function of the female rat F344 rat heart. Journal of Applied Physiology. 96: 822-828.

Casamian-Sorrosal D., Saunders R., Browne W.J., Elliott S. & Fonfara S. 2014. M-mode, two-dimensional and Doppler echocardiographic findings in 40 healthy domestic pet rabbits. Journal of Veterinary Cardiology. 16: 101-108.

Colin M. 1990. Rabbit breeding problems in summer. Rivista di Coniglicoltura. 27: 11-19.

Daimon M., Watanbe H., Abe T., Hirata K., Hozumi T., Ishii K., Ito H., Iwakura K., Izumi C., Matsuzaki M., Minagoe S., Abe H., Murata K., Nakatani S., Negishi K., Yoshida K., Tanabe K., Tanaka N., Tokai K. & Yoshikawa J. 2008. Normal values of echocardiographic parameters in relation to age in a healthy Japanese population: The JAMP study. Circulation Journal. 72: 1859-1866.

Della Torre P.K., Kirby A.C., Church D.B. & Malik R. 2000. Echocardiographic measurements in greyhounds, whippets and Italian greyhounds - dogs with similar conformation but different size. Australian Veterinary Journal. 78: 49-55.

De Heer L.M., Buddle R.P., Vonken E.J., Baaijens F.P., Gründeman P.F., Van Herwerden L.A., Hoerstrup S.P. & Kluin J. 2011. Computed tomography detects tissue formation in a stented engineered heart valve. The Annals of Thoracic Surgery. 92: 344-345.

Diez-Prieto I., García-Rodríguez M.B., Ríos-Granja M.A., Cano-Rábano M.J., Peña-Penabad M. & Pérez-García C.C. 2010. M-mode echocardiographic changes in growing beagles. Journal of the American Association for Laboratory Animals Science. 49: 31-35.

Du Bois D. & Du Bois E.F. 1989. A formula to estimate the approximate surface area if height and weight be known. Nutrition. 5: 303-311.

El-Sayiad G.H.A., Yamani K.O., Tawfeek M.I. & Yassin H.M. 1993. Some traits of doe and young rabbits as affected by breed, parity and diet supplementation under Egypt conditions. Egyptian Journal of Rabbit Science 3: 81-90.

Fontes-Sousa A.P., Brás-Silva C., Moura C., Areias J.C. & Leite-Moreira A.F. 2006. M-mode and doppler echocardiographic reference values for male New Zealand white rabbits. American Journal of Veterinary Research. 67: 1725-1729.

Jenkins J.R. 2008. Rabbit diagnostic testing. Journal of Exotic Pet Medicine. 17: 4-15.

Joy A.D., Jose M.T. & Prabhakaran P. 1985. Carcass characteristics of American Chinchilla crossbred rabbits. Kerala Journal of Veterinary Science. 16: 29-32.

Green C.J. 1975. Neuroleptanalgesic drug combinations in the anaesthetic management of small laboratory animals. Laboratory Animals. 9: 161-178.

Hasenfuss G. 1998. Animal models of human cardiovascular disease, heart failure and hypertrophy. Cardiovascular Research. 39: 60-76.

Kienle R.D. & Thomas W.P. 1995. Echocardiography. In: Nyland T.G. & Mattoon J.S. (Eds). Veterinary Diagnostic Ultrasound. Philadelphia: Saunders, pp.198-256.

Kirberger R.M. 1991. Mitral valve E point to ventricular septal separation in the dog. Journal of the South African Veterinary Association. 62: 163-166.

Kraus A.L., Weisbroth S.H., Flatt R.E. & Brewer N. 1977. Biology and diseases of rabbits. New York: Academic Press, 483p.

Kriz N.G., Hodgson D.R. & Rose R.J. 2000. Changes in cardiac dimensions and indices of cardiac function during deconditioning in horses. American Journal of Veterinary Research. 61: 1553-1560.

Mach K. & Safarova P. 1988. Purebreeding and commercial crossing of broiler type rabbits. Scientia Agricultura Bohemos. 20: 211-216.

Maertens L. & De Groote G. 1990. Comparison of feed intake and milk yield of does under normal and high ambient temperature. The Journal of Applied Rabbit Research. 13: 159-162.

Martin M.W., Darke P.G. & Else R.W. 1987. Short communication: congestive heart failure with atrial fibrillation in a rabbit. Veterinary Record. 24: 570.

Mora C., Fontes-Sousa A.P., Teixeira-Pinto A., Areias J.C.C. & Leite-Moreira A.F. 2009. Agreement between echocardiographic techniques in assessment of the left ventricular myocardial performance index in rabbits. American Journal of Veterinary Research. 70: 464-471.

Nazlıgül A. 1998. Laboratory Animal Breeding. Aydın: Adnan Menderes University Publications, pp.12-23.

Özkan C., Kaya A. & Akgül Y. 2012. Normal values of haematological and some biochemical parameters in serum and urine of New Zealand White rabbits. World Rabbit Science. 20: 253-259.

Poser H., Semplicini L., De Benedictis G.M., Gerardi G., Contiero B., Maschietto N., Valerio E., Milanesi O., Semplicini A. & Bernardini D. 2013. Two-dimensional, M-mode and Doppler-derived echocardiographic parameters in sedated healthy growing female sheep. Laboratory Animals. 47: 194-202.


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