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Year : 2017  |  Volume : 24  |  Issue : 2  |  Page : 147-151

Estimation of gastrointestinal transit time in the West African Mud Turtle, Pelusios castaneus (Schwinger 1812) using contrast radiography

1 Department of Veterinary Surgery and Reproduction, Faculty of Veterinary Medicine, University of Ibadan, Ibadan, Nigeria
2 Department of Radiology, College of Medicine, University of Ibadan, Ibadan, Nigeria

Date of Web Publication20-Jul-2017

Correspondence Address:
Folayemi Omotomilola Olayinka-Adefemi
Department of Veterinary Surgery and Reproduction, Faculty of Veterinary Medicine, University of Ibadan, Ibadan 200284
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DOI: 10.4103/1658-354X.206808

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Background: Gastrointestinal (GI) transit time is a useful diagnostic technique routinely done around the world in human medicine. In veterinary medicine, however, this has only been done in few species in developed nations. With veterinary science, still developing in many parts of Africa, this technique is not routinely done. Our aim was to determine GI transit (GIT) time in Pelusios castaneus, a small sized group of freshwater pleurodira turtles that inhabit the tropics of West Africa.
Materials and Methods: The study group comprised four males and four females with a mean weight of 0.81 ± 0.37 kg. Using a routine feeding technique, 10 ml of dilute barium sulfate suspension was administered orally and the GIT time of the contrast observed and monitored through radiography. The transit time was recorded in hours as it traveled through each section of the GIT. The time for complete contrast excretion was recorded for each turtle.
Results: The contrast mean transit time from the mouth through the esophagus to the stomach was 1.06 ± 0.20 h and the mean onset of gastroduodenal transit was 4.05 ± 0.09 h while mean intestinal transit time was 245.90 ± 53 h. The mean total contrast excretion time was 10.8 ± 2.4 days. The female excretion time was shorter than the males (males: 13.7 ± 3.33 days; females: 7.8 ± 3.27 days), but this was not statistically significant. Our findings were at variance with results obtained among freshwater turtle species that inhabit temperate climates.
Conclusion: These findings suggest an influence of turtles' natural habitat climatic conditions on their GIT time and possibly digestion.

Keywords: Contrast radiography, Pelusios castaneus, transit time

How to cite this article:
Olayinka-Adefemi FO, Ogbole GI, Olatunji-Akioye A. Estimation of gastrointestinal transit time in the West African Mud Turtle, Pelusios castaneus (Schwinger 1812) using contrast radiography. West Afr J Radiol 2017;24:147-51

How to cite this URL:
Olayinka-Adefemi FO, Ogbole GI, Olatunji-Akioye A. Estimation of gastrointestinal transit time in the West African Mud Turtle, Pelusios castaneus (Schwinger 1812) using contrast radiography. West Afr J Radiol [serial online] 2017 [cited 2021 Jun 20];24:147-51. Available from: https://www.wajradiology.org/text.asp?2017/24/2/147/206808

  Introduction Top

The West African mud turtles (Pelusios castaneus) are a group of freshwater turtles belonging to the family Pelomedusidae.[1] They are scattered around the river basins of Western and Middle African countries such as Nigeria, Ghana, Gabon, Mali, and Congo.[2]

Unlike most turtle species listed by the International Union for the conservation of nature (IUCN) as endangered and extinct, P. castaneus, face no global threat of extinction.[3] Recent reports, however, indicate some threats to this specie in their immediate environment. These include practices such as habitat disruption, slaughter during traditional cultural practices, inhumane capture and transport as well as trade in the wildlife market as pets.[4],[5] These factors pose a threat to the medical well-being of turtles and reptiles in general.

Although studies have been done on the digestive tract of fresh and Sea turtles in other parts of the world, report that gives insight into the digestive tract of P. castaneus is sparse.[6],[7] The aim of this study is to describe probably for the first time the radiographic pattern and contrast transit time in the digestive tract of this tropical West African turtles.

  Materials and Methods Top

Eight adult P. castaneus comprising four males and four females with mean body weight of 0.81 ± 0.37 kg were used in this study; however, the age of the turtles was not considered. Approval for the study was obtained from the Institutional Review Board and the Animal Care and Use Research Ethics Committee, University of Ibadan (Reference No. UI-ACUREC/App/2015/041). The turtles were acquired during the months April to July 2015 and kept in a simulated natural environment in the university laboratory and research unit. They were housed in box cages occasionally and allowed a daily swim in an artificial pond.

The turtles were manually restrained and the contrast barium sulfate (READI-CAT ®) was administered through 10 ml syringe tubing orally at a concentration of 80% w/w, volume 7–10 ml/kg per os.

The digital X-ray equipment (Allegers ®) was used to create dorsoventral view images of the turtles using machine settings of 70 kV, 200 mA for 0.3 s. The images were recorded at 0, 15, and 30 min, and subsequently at 1, 2, 24, and every 36 h till total and complete contrast excretion for each turtle was achieved.

All quantitative results were analyzed for mean and standard error values as well as the p-values using the GraphPad® Prism (GraphPad Software, Inc. California, USA) statistical software pack.

  Results Top


Preliminary images (gross images and dorsoventral plain radiographs) which served as the study control gross images of the turtle showed a hard carapace while the plain radiographs of the turtles displayed a radio-opaque bony structures and carapace surrounding a radiolucent coelomic cavity with indistinguishable visceral structures [Figure 1].
Figure 1: (a) Dorsal carapacial view of Pelusios castaneus. (b) Dorsoventral plain radiographic view of P.castaneus in which the coelomic cavity appear radiolucent, Bone and the Shell structures are radio-opaque

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Contrast in the esophagus

At 0 min, the barium sulfate contrast is seen outlining the oral cavity before it progresses to the cranial first part of the esophagus. The average esophageal transit time was 1.06 ± 0.2 h [Figure 2]. In one of the turtles, the contrast was seen to have fully traversed the esophagus and moved into the stomach in an early as 30 min.
Figure 2: Radiograph depicting the radio-opaque contrast material within the esophagus on exiting the oral cavity

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Gastroduodenal and intestinal contrast transit time

The mean time of onset for gastroduodenal transit for the eight turtles was 4.05 ± 0.90 h [Figure 3] while the mean intestinal contrast transit time was 245.90 ± 53.12 h. The contrast material can be seen outlining the pear shaped stomach and entire intestinal tract (S; Stomach, D; Duodenum, J; Jejunum, IL; Ileum, CR; Colon- Rectum as seen in [Figure 4]), signifying a very slow intestinal travel time in this species.
Figure 3: Contrast column within the oesophagus and stomach/gastric region at 2hrs post administration. The stomach is seen as pear shaped and located to the left

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Figure 4: Dorsoventral radiographic X-ray view showing contrast outlining the entire Intestinal tract. S;Stomach, D;Duodenum, J; Jejunum, IL;Ileum, CR; Colon- Rectum

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The mean total contrast excretion time was 10.8 ± 2.4 days, with a range of 2–21 days.

  Discussion Top

This study provided radiographic information useful in outlining the anatomy of the digestive tract of P. castaneus, which is essential in understanding the unique anatomy of their tract.

The associated radiographic anatomic details would allow elucidation and proper management of pathologies such as foreign body obstructions, intestinal ulcerations, and digestive tract lesions. Other field applications of the knowledge of the gastrointestinal (GI) transit time is in the development of efficient diet plans and feed formulations by pet nutritionist, conservation facilities, and turtle pet owners. The information from this study may help identify turtle feed formulation that may interrupt the physiologic transit time patterns and range.

In addition, the study revealed a sex variation in transit time, as male had a comparatively longer transit time compared to females. Although the difference appeared small and not statistically significant (P< 0.05 is considered statistically significant), it raises a concern which a larger study with an appropriate population sample size may help clarify [Table 1]. Nevertheless, this subtle gender difference may be as a result of hormonal or genetic factors, and the clinical relevance would be an interesting issue to investigate in future studies among this species.
Table 1: Summary of transit and excretion time of barium sulphate in Pelusios castaneus, in males and females

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Turtles have a unique rate of metabolism.[8] As ectotherms, they rely predominately on heat from their environment for internal metabolic processes such as respiration and digestion.[9] Like other reptiles, they have a decreased resting metabolism, which consequently cumulates in decreased energy requirements hence digestion is a much slower process in them when compared with other classes of animals.[10]

Diagnostic imaging of the digestive tract of reptiles has been documented in some reptiles such as the ball python, Python regius and the green iguana, Iguana iguana.[11],[12] In chelonians, GI studies to show the transit time of contrast was reported in the spur-thighed tortoise, Testudo graeca, the Hermann's tortoise, Testudo hermanni, the loggerhead sea turtle, Caretta caretta, and in the South American freshwater turtle, Podocnemis unifilis.[13],[14],[15],[16]

The findings from this study showed that transit time in the P. castaneus was slow with the longest transit time recorded during intestinal travel. This agrees with observations of Di Bello (2006) in his study “Contrast radiography of the gastrointestinal tract of sea turtles” and Banzato's (2013) “Review of diagnostic imaging of Snakes and Lizards” that intestinal transit time is longer in chelonians and reptiles respectively.

The total contrast emptying time in the turtles used in this study was 10.8 ± 2.4 days [Table 2]. This greatly differed from similar studies on sea turtles and freshwater turtles. The total transit time in the yellow spotted Amazon river turtle, P. unifilis was on average 17.6 days, the loggerhead sea turtle C. caretta; 20.2 days, Podocnemis expansa; 22.5 days, T. graeca; 26.5 days and Geochelone carbonaria; 42 days.[17],[18],[19] The above figures indicate that although the transit time in the P. castaneus was long as expected in any reptile (when compared with mammals), its transit time is shorter when compared with other reported chelonians.
Table 2: Summary of transit and excretion time in Pelusios castaneus

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A study by Spencer (1998) may best explain the findings of this study. In his study on the “The diet and digestive energetics of the Australian short-necked turtle, Emydura macquariihe concluded that environmental temperature influenced digestion in Testudines.[20] The geographical location of the P. castaneus is the muddy waters of countries like Nigeria, Mali, Ghana, Gabon located in Western and Middle Africa (latitude 4°N and 28°N, longitude 15° E and 16°W) where the climate is classified as hot or tropical.[21] These regions have been characterized has having a uniformly high temperature (as high as 35°C) and sunshine throughout the year.[22] The increased temperatures in these regions is thought to hasten the metabolism processes in the P. castaneus. Previous studies that have been done were in chelonians in Europe and South America (the Greek tortoise, the loggerhead sea turtles, yellow spotted Amazon river turtle) where temperate climate temperatures can go as low at − 10°C. Therefore, it is extrapolated from this study that Tropical climate of the natural habitat of the P. castaneus is most likely responsible for the shorter contrast excretion time that was observed.

Another study that may additionally explain these findings is the relationship between metabolic rates and body size as described by Martinez (2010). This study reported that metabolic rate increases with decreased body size in endotherms especially in birds and this was similar in Reptiles.[23] The results of this study may corroborate this finding as the P. castaneus is small sized, 7–12 inches than previously studied turtles.[24] The freshwater turtle P. unifilis has a size range of 14–27 inches and C. caretta can reach a size of about 35 inches when fully grown. Therefore, turtle size may also explain this difference in contrast excretion time.

Age factor was not considered as a parameter in this study as the aging of reptiles generally and turtles specifically, remain an aspect of modern science still been explored. While P. castaneus have been documented to achieve a maximum longevity of about 41 years in the wild, techniques such as the use of growth rings or skeletochronology used in age estimation of turtles have been described as unreliable and almost impossible to accurately perform.[25]

  Conclusion Top

The results of this study create a baseline radiological database for the P. castaneus which has not been documented before this study. This creates a radiological reference for clinicians and a scientific reference for conservationists, educationist, and Herpetologists. A scientific bank that will be useful for research comparisons and whose information can be extrapolated for other turtles, giving a better understanding of Testudines, as a scientific group.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

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Banzato T, Selleri P, Veladiano I, Martin A, Zanetti E, Zotti A. Comparative evaluation of the cadaveric, radiographic and computed tomographic anatomy of the heads of green iguana(Iguana iguana), common tegu (Tupinambis merianae) and bearded dragon (Pogona vitticeps). Anat Histol Embryol 2013;42:453-60.  Back to cited text no. 11
Banzato T, Hellebuyck T, Van Caelenberg A, Saunders JH, Zotti A. A review of diagnostic imaging of snakes and lizards. Vet Rec 2013;173:43-9.  Back to cited text no. 12
Meyer J. Gastrografin as a gastrointestinal contrast agent in the Greek tortoise (Testudo hermanni). J Zoo Wildl Med 1998;29:183-9.  Back to cited text no. 13
Holt PE. Radiological studies of the alimentary tract in two Greek tortoises (Testudo graeca). Vet Rec 1978;103:198-200.  Back to cited text no. 14
Valente AL, Parga ML, Velarde R, Marco I, Lavin S, Alegre F, et al. Fishhook lesions in loggerhead sea turtles. J Wildl Dis 2007;43:737-41.  Back to cited text no. 15
Lopes LA. Determinação do tempo do trânsito gastrintestinal em Podocnemis expans a Schweigger, 1812 (tartaruga-da-amazônia) (Testudine s, Podocnemidida e) 52f Dissertaçço (Mestrado em Ciências Veterinárias)-Faculdade de Medicina Veterinária, Universidade Federal de Uberlândia, Uberlândia; 2006.  Back to cited text no. 16
Di Bello A, Valastro C, Staffieri F, Crovace A. Contrast radiography of the gastrointestinal tract in sea turtles. Vet Radiol Ultrasound 2006;47:351-4.  Back to cited text no. 17
Santos AL, Ferriera CG, Pinto JG, Lima CA, Veira LG, Brito FM. Radiographic anatomy aspects and gastrointestinal transit time in Podocnemis unifilis, Troschel. 1848 (Testudines, Podocnemididae). Maringa 2010;32:431-5.  Back to cited text no. 18
Pizzutto CS, Mariana AN, Guimaraes MA, Correa SH. Radiological anatomy and barium sulfate contrast transit time in the gastrointestinal tract of the red- footed tortoise (Geochelone carbonaria). Bol Asoc Herpetol Esp 2001;1:32-6.  Back to cited text no. 19
Spencer RJ, Thompson MB, Hume ID. The diet and digestive energetics of an Australian short-necked turtle, Emydura macquarii. Compa. Biochem. Physiol 1998;121:341-349.  Back to cited text no. 20
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  [Figure 1], [Figure 2], [Figure 3], [Figure 4]

  [Table 1], [Table 2]

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