Australian veterinary journal | 2021
Design and development of a biological implant for long term intravaginal retention in cattle.
Abstract
OBJECTIVE\nDesign, develop and trial an intravaginal device able to remain within the bovine vagina for up to 6\u2009months, accommodating various technologies, while not adversely affecting the cow, or pregnancy.\n\n\nMETHODS\nDevice scoping required minimal interference with vaginal drainage, no constant pressure on any single point of the vaginal mucosa and minimal footprint on the vaginal floor. A polycarbonate prototype was developed consisting of a central cargo space to house sensors and battery, with a separate retention module. Mathematical modelling informed the required length and flexibility of the arms on the retention module to reduce pressure necrosis and inflammation within the vagina. The prototype was initially trialled, with a loaded cargo pod, for 4\u2009weeks in five non-pregnant cows. Cows were monitored for signs of systemic infection and inflammation by collecting blood samples for haematology and acute phase inflammatory proteins. Cows were also assessed for general demeanour, signs of discomfort and positioning of the device. Later, the device was inserted into 20 early pregnant cows, with 20 contemporary, untreated controls. Cows were monitored, as in the initial trial, every 4\u2009weeks for the next 5 to 6\u2009months until calving.\n\n\nRESULTS\nIn Trial 1, there was 100% retention with no adverse effects. In Trial 2, device retention was 75% until calving with no adverse effects on cow health or pregnancy.\n\n\nCONCLUSIONS\nWe describe the longest successful deployment of an intravaginal device in pregnant and non-pregnant cattle, with long-term retention, no adverse effects and 28\u2009cm3 of cargo space.