Ultrasound imaging and sexing, lizard style.
Animal breeders can face different obstacles when trying to establish a pregnancy. For the Gila lizard, successful breeding firstly requires accurate and reliable sexing, which can be carried out by veterinary ultrasound (www.vetimagesolutions.co.uk).
Identification of the henipenes by ultrasonography is not the most effective method by which to sex male Gila lizards. The presence of a tubular structure in the female is almost identical to the hemipenes, thus confounding results. Consequently, an alternative and more reliable method is sought. Dr. Mark Seward recommends sexing Gila lizards by their gonads, ideally when they reach 2.5 years of age, with the initiation of breeding 1 year later. The gonads are situated below the liver, which can be easily detected following ultrasound imaging, and approximately one third up from the vent. The liver may then be used as a 'focal' point before attempting to identify the gonads.
In addition, sexing during the springtime is optimum; the testes will become enlarged and follicular development is initiated, resulting in easy detection of the ovaries. Ultrasound imaging should then be able to identify follicles ranging between 0.5-3.5cm in diameter, dependent on the occurence of ovulation, resulting in differentiation between males and females. Dr. Seward also reveals that an empty stomach and a full bladder can greatly aid in accurate sexing, with the latter enabling the gonads to be clearly separated from other tissues.
Whilst for some members of the animal kingdom breeding is taken for granted, sexing must firstly be accurately carried out. It is easy to envisage the frustration a breeder would experience if two males or two females were erroneously matched. Ultrasonography can therefore be greatly advantageous prior to breeding, highlighting yet another application for ultrasound imaging.
This article was written by Melissa Robbin, PhD.