A previously described/developed koffe-bait was not considered suitable for the Philippines, due to concerns about it being attractive to humans.
As a reference bait, the chickenhead-bait was suggested. This bait was initially also used for oral vaccination of foxes in Europe. But the larger vaccine capsule intended for dogs could not be slid underneath the skin of the chickenhead. It was therefore decided to replace the chickenhead with larger segments of chickenneck.
As an inexpensive alternative, rinsed segments of intestine was used as a completely new bait (costs per bait:0.01 U$). These intestine baits were prepared from sections (5–8 long) from the large intestine of domestic pigs (Sus domesticus). After boiling for ten minutes, the baits become more "elastic" and would increase the bait handling time.
Finally, the cleaned serosa of the smaller intestine of pigs was used as a matrix for other baits. These baits were filled with local available materials (Table ), in order to see if these additives would increase bait-acceptability compared to the intestine bait.
Description and costs (only costs of material) of baits with the scrosa of the smaller intestine of pigs as bait matrix (scrosa – bait).
An empty vaccine container (6.5 × 3.0 × 0.7 cm), a polyvinyl-chloride capsule with serrated edges and sealed with an aluminum cover foil, was placed manually, inside the baits. All dogs offered a bait were owned, some of the animals were restricted, but most animals were free roaming and were found in doorways, allays, yards, or on the streets adjacent to the owners dwellings.
Young dogs, less than three months old, were excluded from the bait trials. The baits were offered to the dogs by the vaccinators only, baits were not handed out to the owners.
The bait trials with the (boiled and raw) intestine-and chickenneck baits were carried out in rural areas around Agoo and the North La Union campus of Don Mariano Marcos Memorial State University campus in Bacnotan, both in the province of La Union, Philippines.
A bait was recorded as 'accepted' when the dog had actually consumed the entire bait. When the dog only licked or sniffed at the bait, or did not show any interest at all, it was recorded as 'not accepted'. Sometimes, dogs would take the bait and ran away with it, here the outcome of the vaccination attempt was classified as 'unknown'. Although the dog accepted the bait, it could not be ruled that the animal would cached the bait for later consumption, or would loose interest and abandon it. If a dog ran away, before a bait was offered, it was recorded as 'not offered'. However, sometimes it was possible to offer another bait to the same dog during a second vaccination attempt. Otherwise, the animals were only once offered a bait. Of course, it cannot be avoided that some unrestricted dogs were encountered twice or more often. To avoid this as much as possible, the neighbourhoods were visited only once. During the field trials with the (boiled and raw) intestine- and chickenneck baits, also the fate of the vaccine container was recorded; P-the discarded container was punctured, NP- the discarded container was not punctured; SW-container was swallowed almost immediately, probably not punctured, SW/P-container was punctured and subsequently swallowed. An animal was considered vaccinated when it had accepted the bait and, subsequently, the vaccine container was punctured (P and SW/P). All vaccine containers were recovered by the vaccinators and the fate determined. The field trials were approved by the appropriate local and national committees and authorities.