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Combinations of drugs we used The dramatic improvement in success shown in the table below (when we combined subq oxytocin and Lutalyse) led to a long series of experiments to determine the best proportions of each drug. A common side effect of Lutalyse is diarrhea. Because the incidence of diarrhea rose 231% when the dose of Lutalyse was increased from 1.0 mg/kg to 3.0 mg/kg, and the success rate dropped, we did not pursue dose combinations using 3.0 mg/kg or more of Lutalyse. The table above shows the various combinations of prostaglandins and oxytocin that we tried initially. Oxytocin (10u/kg) + Lutalyse (1.5mg/kg) had a 78% success rate compared to a 32% success rate with oxytocin alone; a dramatic improvement! In the early studies the oxytocin and Lutalyse were given by separate injections but later on, when the drugs were combined into one injection, the success rate was even higher (Instead of giving separate injections of oxytocin and Lutalyse ten minutes apart we decided to combine them into one injection). The combination was at least as effective and a lot less time consuming as shown below. The manufacturer of Lutalyse suggests that it be stored at room temperature. Oxytocin is…

Early work with various drugs and drug combinations   The tables below show how poor the results were using oxytocin alone (Remember that “success” for us means that the turtle laid all its eggs after one injection).  We pooled the intraperitoneal and subq results in the first table because they were similar and very different from the results with PGF-2 as the tables later in this section show. More details on the effectiveness of PGF-2 are highlighted in section nine, “Discovering the importance of PGF-2.” Because of these poor results with oxytocin, a success rate of better than 40% became our target when we experimented with other agents. The table below shows a number of other agents that we had no success with on their own. These injections were given subq by the base of the tail. We used normal saline as a control and, of course, it had no effect. One striking failure was arachidonic acid, the precursor to the prostaglandins. It is known to induce oviposition in birds (Wechsung and Houvenaghel 1981), and lizards (Guillette et al.1992). We tested a wide range of doses. Since arachidonic acid is the precursor for many prostaglandins we thought it might be…

Designing the best environment for oviposition Designing the best environment for oviposition   We had learned in previous years how important it was to shield induced turtles from being frightened by movements around them. We used to suspend them over a wet towel in a closed closet to achieve this goal. This worked fine for painted turtles (Chrysemys picta picta) and box turtles (Terrapene species) but such a procedure was time consuming and some species became agitated if suspended (snapping turtles). Placing them in deep water also worked but it required frequent observation to remove the eggs before they were damaged, and it was also time consuming. We eventually decided on using a wide spaced grid that the eggs could fall through onto a moist surface below. Constructing the grid took about twenty minutes but it could be reused hundreds of times and was safe for the turtles and the eggs. The grid was placed snugly into an opaque storage container and then the container was covered so the turtles could not see their surroundings. We wondered if noise affected the laying process. To test this we put the plastic tubs outside the lab in an alleyway that diesel powered…

Determining the techniques we would use Before we could begin to experiment with the different drugs that could induce oviposition we had to design a standard method of giving injections, a standard site for those injections and a consistent environment to contain the turtles. Environmental concerns included the possible need for noise control, how to blind the turtles to potentially frightening movements around them, preferred temperatures and deciding if the outcome would be better if the turtle was kept dry or was kept in water. We also had to adopt a method to label the turtles so we could identify them days or weeks later for follow-up. During these initial tests we used 10 units of oxytocin per kilogram as our standard dose because that was found to be most effective by John Tucker when he was working with wild RES in Illinois in 2007 and by us in the 1990s (see the “2007 article” section of this web-site). We also adopted the use of a grid as Tucker did in 2007 because it was the easiest method to keep the oviposited eggs safe from damage. When we were faced with a choice between two methods that had similar outcomes…

Establishing a pattern for working with red eared sliders In the spring of 2008 we found ourselves at the Concordia Turtle Farm in Wildsville, Louisiana. Concordia is the largest turtle farm in the United States. It’s owned by the Evans family. They were very supportive of our goals and gave us access to a pond that had 5,000 red eared sliders (Trachemys scripta elegans) in it to use for our research. They also gave us a shed to work in with power and water, and an ATV to move the animals between the pond and the shed. In later years we became concerned that the reproductive physiology of all turtles was not the same. To deal with that problem the Evan’s family also gave us access to a spiny softshell turtle (Apolone spinifera) pond so we could test the new methods we were developing on a species that was very different from red eared sliders (RES). The first challenge was to be uniform in our approach. For our results to be of any use we would need to treat every turtle the same. First we defined our goal as having every turtle lay all its eggs after the first induction. We called…

The background of our research During a visit to John Legler’s lab at the University of Utah in 1977 we met a young graduate student named Jim Berry. I explained to Jim that we liked to keep hatchling turtles for a year or so, release them, and then replace them with new hatchlings. When I complained about how difficult it was to catch the hatchlings he suggested I learn how to “make them.” Jim then showed me how they had been experimenting with injecting oxytocin intraperitoneally to induce turtles to lay their eggs (Ewert and Legler 1978). I didn’t realize it then, but that simple lesson was to change our lives. From 1978 to 2005 we tried to induce about 245 turtles (see web-site section labeled “2007 article”). Our first obstacle was to find the gravid turtles. I made it a habit to take my vacation time in June and we would go out most evenings and mornings to collect turtles that were looking for a nesting site in our area of Pennsylvania, USA.  We sought aquatic turtles that were emerging from the water to lay their eggs and eastern box turtles (Terrapene carolina) which we found in known nesting areas.…

Executive summary October, 2026   The tables and figures in this section summarize our key findings. Our recommendations for inducing turtles are based on this data. The recommendations can be found under the web-site heading “PIM instructional.” PIM instructional consists of a PDF that outlines our suggestions for a successful induction and a series of videos that details the practical techniques. Here’s our key findings: Large numbers of red-eared sliders (RES) were involved in multiple trials over several years to determine the most effective dose of Lutalyse in healthy RES. The most effective dose was 1.5 mg/kg given subcutaneously. ———————————————- The figure above is a graphical representation of the relative effectiveness of various doses of subcutaneous Lutalyse used to induce oviposition. ———————————————– This figure illustrates the dramatic improvement in effectiveness when Lutalyse is used when compared to oxytocin alone. Large numbers of RES were involved in these trials which were done over several years. Note the slight improvement when Lutalyse is used alone compared to various combinations. ————————————————— Smaller numbers of RES were involved in this trial to determine the best induction method for RES stressed by underfeeding. The success rate was dramatically improved by adding an alpha-agonist drug to the Lutalyse.…

Results of others that used our methods   Our research has focused on a relatively small number of species. If you read the previous section (section 18) about our experience with Australian snake necks or section 15 on soft shell turtles it’s clear that not all species respond the same way to any given induction method. For this reason we have been reaching out to others to find out what results they have had using Lutalyse with or without an alpha-agonist. The entries on the lists that follow sometimes represent just one turtle of the indicated species but sometimes it represents several. Usually we’ve received very limited information. In most cases we have no idea if our protocol of injection technique, using an opaque container and the turtle being left undisturbed was followed. Where we were given any additional information that data is indicated after the species name. You may recall that, for our purposes, “success” is defined as laying all eggs after one induction. Successful inductions: Astrochelys radiata: radiated tortoise. Chelonoidis denticulata: yellow footed tortoise. Eight kg, 1.2 mg/kg. Cuora galbinifrons: Indochinese box turtle. Cuora mccordi: McCord's box turtle. Emys blandingii: Blanding's turtle. Lutalyse only. Also some unsuccessful inductions.…

Working with the Australian snake neck turtle     The Eastern snake neck turtle is very different from any of the North American turtles we have worked with. It is an exclusive carnivore with forward facing eyes. It has a very long neck and a narrow head so it can seek out food in hard to reach places.     Like many North American species, snake necks are capable of laying two, or even three clutches a year. The big difference is a result of the Australian climate. In many areas prolonged droughts are common. Though the adults are resistant to dehydration, nest building becomes difficult in dry soils so these turtles have evolved to be able to hold their eggs for long periods while still maintaining the egg’s fertility. So there must be some biochemical mechanism to maintain the oviducts in a quiescent state until the rains arrive. However, there are limits to this egg holding capability since we found the eggs were no longer viable after being held for over two months in one case. The unique challenges: There was no turtle farm that was breeding snake necks where we could duplicate the availability of gravid females like…

Are there long term effects on reproductive behaviour after inducing every clutch of Red-eared sliders with Lutalyse for eleven years?   Because we were running the experiments with Australian snake necks simultaneous with the evaluation of long term behavior of RES, and only had limited space in our elevated ponds, we had to reduce the number of RES to a manageable number. We selected four females that we had been inducing the longest. After they emerged from brumation in 2020 we no longer induced them to lay their eggs. We followed their nesting habits for the following six seasons. They laid their eggs in the nesting site illustrated below. The site featured shade and full sun. The soil was a sandy loam. It measured 640mm by 640mm.       The number of clutches per year varied per individual female and between females with no detectable pattern. They laid between one and four clutches per season. For the first five seasons they all dug normal nests and laid their eggs. However, during the final season, one of the females would not lay her last clutch in the nesting area and proceeded to drop those eggs in the water over a…