The complex process of vaccinating pigs is time consuming and requires direct interaction between humans and animals, or so we thought. A study in Nature Scientific Reports in February 2023 details a successful study investigating the possibility of presenting pigs with a device that they use to apply a vaccine to themselves. Conducted by US researchers, the study indicates that understanding and appealing to pigs’ tendencies to root around in their surroundings offers a more efficient and effective vaccination strategy. 

Time for a change 

The authors note that in the US, pig producers are “experiencing a shortage in labour”. Thus, agriculture sectors “have and will need to continue increasing mechanisation” and pursuing “technological advances to reduce labour requirements”.  

“Pig producers are now seeking smart farming, digital farming, and precision farming solutions.” 

The current approach to vaccine administration requires “significant time” and “direct interactions” that “interrupt normal behaviour” and “can be a stressful time for the animal and workers”. Clearly, there is an unmet technological need.  

Enter environmental enrichment (EE) 

Environmental enrichment describes the stimulation of a captive animal’s brain with the effect of improving the animal’s quality of life. For many countries, EE is a requirement for commercial pigs, and is “encouraged” elsewhere.  The authors suggest that current EE devices “often do not accommodate the behavioural need for pigs to root and push/dig”.  

“Most awake and active behaviours of pigs involve rooting and other oral/facial/nasal behaviours (ONF).” 

In the article, they explore prototype EE devices based on the rooting motion, resulting in a rewarding “spray in their ONF regions”. Using this method to encourage self-administration of an oral vaccine, the researchers were looking for pig interactions and antibody responses. Pigs were “encouraged to interact with the sprayer” through the inclusion of a maternal pheromone and the “novelty of the sprayer”.  

Oral vaccination approaches 

The traditional approaches to oral vaccine administration include water system methods, which sometimes means the whole population accessing the system must be vaccinated. Furthermore, oral vaccines for swine are “avirulent live cultures” that are only viable for a few hours. Thus, pigs can easily be excluded from vaccination during the short window of opportunity.  

The study 

The hypothesis for the study was that accommodating “natural pig behaviours using a form of operant conditioning” would enable pigs to self-vaccinate. This would save labour and possibly improve vaccine delivery efficacy. They used the target species (domestic pigs) as found on farms, with “facilities and procedures” modelled after “common practices on farms”.  

The results demonstrated a “significant elevation in IgG and IgA response in all pigs”, as is “consistent with a vaccine-type antibody response”. Indeed, pigs that self-administered that vaccine had “equal or higher IgA in their oral fluids” than the hand-drenched pigs 21 days after vaccination. This is believed to be because self-administration delivers “equal or more antigen to more mucous membranes”.  

Although the approach relied on pig behaviour, the antibodies and behaviour data confirm that all pigs were vaccinated. No risk of over vaccination is perceived, as is the case when administering vaccines through watering devices. However, future systems “may use tracking systems to only turn on the sprayer if a given pig has not been vaccinated”.  

Benefits of the device 

The device used was “mechanical and had no electronic or plumbing parts” and could be used to administer other animal health products beyond vaccines. For the “newer smart-barn systems”, it could be modified to contain electronic valves so that different liquids or powders could be used.  

It is not clear if this technology will work for killed vaccines, intranasal vaccines, or those usually given as intramuscular injection. However, the potential to apply this device to feral swine would allow vaccination, medication, sterilisation, or surveillance of a population.  

To hear more about novel technological advances in vaccination, join us at the World Vaccine Congress in Washington this April.