Design and development of a biological implant for long term intravaginal retention in cattle

Research output: Other contribution to conferenceAbstractpeer-review


Most studies investigating the use of intravaginal devices in cattle have focused on the development of controlled internal drug release (CIDR) and progesterone releasing intravaginal devices (PRID). These devices are placed for up to 18 days duration for the specific purpose of manipulating the oestrous cycle. There is minimal information on a multipurpose device that could be retained intravaginally for long-term use in non-pregnant and pregnant cattle, with only one study investigating the use of an intravaginal temperature transmitting device in 18 non-pregnant Holstein heifers for 107 days. The aim of this project was to design and develop an intravaginal implant able to accommodate varying technologies, that would not adversely affect the cow, or pregnancy and can remain within the vagina for at least 6 months. Such a device would be useful to carry sensors like thermometers, XYZ accelerometers, vaginal electrical resistance sensors, micro cameras, pedometers, and transmitters.

Materials and methods
During development, consideration was given to the following points: 1) The intravaginal device should not interfere with vaginal drainage; 2) The intravaginal device should not place significant, constant pressure to any single point of the vaginal mucosa to prevent pressure necrosis; 3) The intravaginal device should have minimal footprint on the ventral vaginal floor to avoid impairment of vaginal drainage, and also reduce any potential adverse effects on the urethral opening.
A prototype was developed consisting of a standard central core to house sensors and battery, and a separate retention module. Mathematical modelling was performed to determine the ideal length and flexibility of the arms on the retention module to reduce the possibility of pressure necrosis within the vagina. Plastic injection moulding techniques using acrylic were utilised to develop the initial prototypes, however due to strength and moisture condensation issues, the material was replaced with ultrasonically welded polycarbonate. The final prototype was initially trialled with a loaded cargo pod for 4 weeks in 5 non-pregnant cows, with 100% retention and no adverse effects. These were inserted into the cranial vagina using a custom-made applicator. Later it was inserted into 20 early (2 to 3 months) pregnant cows, with 20 contemporary controls. Cows were monitored every 4 weeks until calving for signs of systemic infection and inflammation by collecting blood samples for haematology and measurement of acute phase proteins. Cows were also assessed for general demeanour, signs of discomfort and a vaginal exam using an endoscope was performed to confirm the presence and positioning of the device, and to ensure adequate vaginal drainage.

Device retention was 85% until calving and there were no adverse effects from long-term device retention on cow health or pregnancy.

To our knowledge, this project describes the longest successful deployment of an intravaginal device in cattle with long-term retention and no adverse effects. The capacity of the device to carry a payload up to 11 cm long and 1.8 cm wide within its core module will make it a useful tool for incorporating various sensors for remote monitoring of various behavioural and physiological aspects.
Original languageEnglish
Number of pages1
Publication statusPublished - 19 Aug 2019
Event2019 Northern Beef Research Update Conference: Bush to bright lights - Brisbane Convention & Exhibition Centre, Brisbane, Australia
Duration: 19 Aug 201922 Aug 2019 (program and abstracts)


Conference2019 Northern Beef Research Update Conference
Abbreviated titleBeef Research
Internet address

Grant Number

  • 0000005245


Dive into the research topics of 'Design and development of a biological implant for long term intravaginal retention in cattle'. Together they form a unique fingerprint.

Cite this