Loggerhead sea turtles (Caretta caretta) are among the most frequent victims of bycatch in drifting longlines, and the ingestion of fish hooks and fishing lines is one of the most frequent causes of death of sea turtles. The aim of this study was to evaluate whether coelomic ultrasound (US) can be decisive, not only for diagnosis but also to optimize surgical planning based on preoperative evaluation of the bowel conditions and, in addition, to see if there are characteristic sonographic findings in sea turtles associated with the ingestion of fishing lines. Physical examination, hematology, blood chemistry, radiographs, and US examination were performed in 37 loggerhead sea turtles with suspected or known ingestion of fish hooks or monofilament fishing lines. During the ultrasonographic examinations, the loggerhead sea turtles were placed in dorsal recumbency and the prefemoral left and right acoustic windows were used. Nine wild loggerheads had sonographic findings of intestinal and coelomic abnormalities, and the sonographic images were compared with the surgical findings. Ultrasonography positively identified the foreign body in 89% (8/9) animals. The presence of intestinal plication (in all loggerhead turtles) and ultrasonographic visualization of the linear foreign body was always consistent with the ingestion of a fishing line. In sea turtles, fishing lines cause a corrugated appearance in the small intestine due to increased/unproductive peristalsis. The affected small bowel loops are usually dilated with fluid. In the present study, coelomic US allowed us to make a thorough evaluation of the characteristics, number, and severity of the bowel wall lesions in the animals, thus ensuring the planning of a correct surgical procedure. We suggest that US examination of the coelomic cavity should be complementary to radiographic survey in cases of suspected ingestion of fish hooks and fishing lines by sea turtles.

A wide variety of digestive diseases have been reported in sea turtles (Glazebrook et al. 1989; Gordon et al. 1993; Hasbún et al. 1998). Some of these occur naturally but other conditions, such as the digestive lesions associated with the ingestion of fish hooks, monofilament fishing lines, and crude oil, are essentially a result of human activities (George 1997). Worldwide, sea turtles are caught incidentally by trawl, pelagic longline, and coastal gillnet fisheries (Hays et al. 2003; Lewison and Crowder 2007; Peckham et al. 2007).

Captured sea turtles are usually released back into the sea with a fish-hook still lodged, and it is estimated that between 20% and 30% of these animals could die of the lesions, mostly caused by monofilament fishing lines (Aguilar et al. 1995; Casale et al. 2007). However, the mortality rate is likely underestimated, with the hook localization and length of fishing lines influencing the prognosis (Ryder et al. 2006).

When a sea turtle is hooked by longline gear, it faces substantial risks depending on where the hook is embedded. Most often, hooked turtles are not hauled aboard, as fishermen will often cut the line as soon as they are able to identify the species captured (Tomás et al. 2008). If the hook and line are ingested, they may produce intussusception and other gut pathologies that can be lethal (Orós et al. 2005). Ingestion of hooks and monofilament lines has resulted in ulcerative and fibrinous esophagitis, fibrinonecrotic gastritis, fibrinous and necrotizing enteritis, intestinal intussusception, severe coelomitis, and septicemia (Orós et al. 2005). Fishing lines disable digestive functions, leading to starvation and death after a fairly long period. In cases with a relatively long fishing line extending to the intestine but firmly anchored by the hook in an anterior position (usually the esophagus), peristalsis of the intestine around the fishing line tightens the line until it either perforates the intestine or causes intussusception, or both (Bjorndal et al. 1994; Orós et al. 2004; Casale et al. 2007). Moreover, as the peristaltic movement pushes the line caudally, it produces plication from the point of hook attachment. Sea turtles with a long monofilament line attached to the hook that runs out through the cloaca or mouth (Di Bello et al. 2006a) have a worse prognosis than those in which the hook alone is present.

An external line is not always seen in sea turtles with bowel plication, and the nonradiopaque nature of nylon fishing lines (as well as plastic bags, plastic fragments, etc.), along with the frequent absence of clinical signs, can delay the diagnosis of gastrointestinal obstruction, plication, perforation, intussusception, etc. Radiography can be challenging and limited in its usefulness in chelonians because of difficulties in interpretation caused by the superimposition of the carapace and plastron and the low volume of intracoelomic fat that together limit subject contrast (Williams et al. 2013). In these cases, contrast radiography of the gastrointestinal tract using 60% barium sulfate solution or water-soluble contrast media could help in the diagnosis, but contrast medium administration presents some difficulties that compound due to the slow intestinal transit time in sea turtles (Di Bello et al. 2006b). In aquatic animal medicine, ultrasound (US) is a very helpful and easy-to-use tool for clinical investigation and diagnosis (Martorell et al. 2004; Valente et al. 2007; De Majo et al. 2016).

Ultrasonography has been used as a noninvasive method to evaluate the coelomic organs of sea turtles (Schumacher and Toal 2001; Valente et al. 2007; Pease et al. 2010). We performed coelomic US examination in 37 juvenile or subadult loggerhead sea turtles (Caretta caretta) captured with suspected or confirmed ingestion of fish hooks or monofilament fishing lines. In 76% (28/37) of the loggerhead sea turtles, the US did not reveal abnormalities. However, in 24% (9/37) of sea turtles the US technique and the acquired images suggested the presence of monofilament fishing lines inside the intestine. The US images were compared with surgical findings. Our aims were to evaluate whether coelomic US may be decisive, not only for diagnosis but also to optimize the surgical procedures, based on a preoperative evaluation of bowel conditions, and to determine if there are characteristic sonographic findings in sea turtles associated with the ingestion of fishing lines.

Between January 2014 and October 2016, 37 loggerhead sea turtles were referred to the Surgery Section at the Department of Veterinary Medicine at the University of Bari (Italy) after having been taken to the local Adriatic Sea turtle rescue center for treatment of accidentally ingested fishing hooks and lines. The majority of the animals were found either drifting at sea or stranded on the coast, and they were referred to the rescue center by volunteers. Upon admission, physical examination was made of each sea turtle, with detailed recording of its biometrics and clinical conditions: curved carapace length notch-to-tip ranged from 34.5 to 68.8 cm (mean 47.5±16 cm), curved carapace width was 33.1 to 64.5 cm (mean 45.2±14 cm), and weight was 5.3 to 39.0 kg (mean 15.8±11.8 kg). Core body temperature was measured from the cloaca, and blood samples to measure plasma biochemical and hematologic values were obtained.

All loggerhead sea turtles underwent dorsoventral, lateral, and craniocaudal radiographic examinations. We examine 37 loggerhead sea turtles by US. Indications for use of US included presence of the tip or a loop of a fishing line coming out of the mouth or cloaca, radiographic evidence of one or more hooks lodged in various areas of the digestive tract, and entangled turtles in very poor general condition.

We used a portable US device (MyLab™ 30 Gold Vet, Esaote, Firenze, Italy) with multifrequency probes (Convex CA 123, 5–8 MHz, Esaote). The prefemoral left and right acoustic windows were used and contact was maintained with acoustic coupling gel. The transducer was oriented mainly on the horizontal plane. Color and pulsed Doppler imaging were applied on the vessels. During the ultrasonographic examinations, the loggerhead sea turtles were placed in dorsal recumbency and held in place by balancing their carapace on a foam mattress. The animals were manually restrained and the flippers were extended as needed. No sedation was necessary. To reduce turtle stress, the eyes were blinded by applying a self-adhesive elastic bandage around the head, and the body surface was kept wet using a soaked towel.

Ultrasound assessment was made of gastric and intestinal wall thickness and layering. The presence of gastric or intestinal distension, the gastrointestinal contents, intestinal plication, and any presence of effusion were assessed. The presence and location of any foreign body were recorded. Animals with clinical, radiographic, and US evidence of hooks and fishing lines were subjected to esophageal or gastrointestinal surgery (or both) to remove them. A detailed report was drafted during surgery for comparison with US images.

On clinical evaluation, 32% (12/37) loggerhead sea turtles were in a poor state of nutrition. We found that 11% (4/37) of loggerhead sea turtles had the tip or a loop of a fishing line running out of the cloaca, 73% (27/37) of loggerhead sea turtles had a fishing line running out of the mouth, and one turtle showed a hook wedged in the oral cavity, with the fishing line lodged caudally inside the esophagus. No clinical symptoms were apparent in 68% (25/37) subjects. Abnormal biochemical and hematologic results were obtained in 27% (10/37) of loggerhead sea turtles. Hyperglycemia, hypoalbuminemia, and hypouremia were the most common biochemical anomalies, and the most frequently occurring hematologic anomaly was thrombocytosis.

After radiographic examinations, 97% (36/37) of sea turtles showed one or more hooks lodged in various areas of the digestive tract. Of these, hooks were located in the oral cavity (n=1), in the cervical esophagus (n=30), and in the intracoelomic part of the esophagus close to the bronchial bifurcation (n=5), and one sea turtle had hook fragments in the cervical esophagus and in the proximal colon. One sea turtle had ingested two hooks; one was in the esophagus and the other in the distal ileum.

The US findings were considered normal in 76% (28/37) of loggerhead sea turtles. Ultrasound findings of intestinal and coelomic abnormalities were noted in 24% (9/37) of loggerhead sea turtles (Table 1). There was coelomic fluid between the bowel loops of 24% (7/37) of the loggerhead sea turtles. Plication of the small intestine and colon was present in 19% (7/37) sea turtles (Fig. 1a), and the affected intestinal loops were dilated with fluid. A linear foreign body with posterior acoustic shadowing was detected sonographically along the mesenteric margin in 22% (8/37) of loggerhead sea turtles.

Table 1

Clinical, radiographic, ultrasound, and surgical findings in nine loggerheads (Caretta caretta) found stranded on the Adriatic coast of Italy, with hook and fishing longlines inside the gastrointestinal tract.

Clinical, radiographic, ultrasound, and surgical findings in nine loggerheads (Caretta caretta) found stranded on the Adriatic coast of Italy, with hook and fishing longlines inside the gastrointestinal tract.
Clinical, radiographic, ultrasound, and surgical findings in nine loggerheads (Caretta caretta) found stranded on the Adriatic coast of Italy, with hook and fishing longlines inside the gastrointestinal tract.
Figure 1

Case 1. Ultrasound scan of a loggerhead (Caretta caretta) found stranded on the Adriatic coast of Italy, with two hooks located in the cervical esophagus and fishing line protruding from the cloaca. (a) Longitudinal ultrasound scan (right prefemoral access) showing the hyperechogenic linear image of the longline in the medial-distal small bowel tract along the mesenteric margin (filled arrow) and consequent anomalous plication of the loops (empty arrows). (b) Intraoperative image: Hyperemic, bundled loops with marked plication of small intestine and colon due to ingested fishing line.

Figure 1

Case 1. Ultrasound scan of a loggerhead (Caretta caretta) found stranded on the Adriatic coast of Italy, with two hooks located in the cervical esophagus and fishing line protruding from the cloaca. (a) Longitudinal ultrasound scan (right prefemoral access) showing the hyperechogenic linear image of the longline in the medial-distal small bowel tract along the mesenteric margin (filled arrow) and consequent anomalous plication of the loops (empty arrows). (b) Intraoperative image: Hyperemic, bundled loops with marked plication of small intestine and colon due to ingested fishing line.

Close modal

In all loggerhead sea turtles, the small intestine was diffusely thickened with mucosal edema (Fig. 2) but intestinal layering was normal. In one sea turtle, the linear foreign body had penetrated the thickness of the intestinal mucosa (Fig. 3). The US examination suggested a small bowel perforation in two sea turtles (Fig. 4a), although there was no radiographic evidence of pneumocoelom. There was free coelomic fluid present in these animals. Sonographic evidence of intussusception of the ileum into the colon was present in one sea turtle but a linear foreign body was not detected (case 2, Table 1). In cross-section, the intussusception appeared as a circular lesion of concentric ‘onion rings.' The outer intussuscipiens was edematous and hypoechoic whereas the inner intussusceptum was hyperechoic (Fig. 5a). In an entangled sea turtle with bilateral proximal flipper laceration, poor general body condition, and a reluctance to feed, radiographs did not reveal the presence of hooks while US revealed a linear foreign body (case 4, Table 1).

Figure 2

Case 3. Transverse ultrasound scan (right prefemoral access) of a stranded loggerhead (Caretta caretta) with no longline present but with a single hook in the cervical esophagus. There is evidence of increased wall thickness and attenuated echogenicity of the mucosa compatible with small bowel wall severe edema (asterisk).

Figure 2

Case 3. Transverse ultrasound scan (right prefemoral access) of a stranded loggerhead (Caretta caretta) with no longline present but with a single hook in the cervical esophagus. There is evidence of increased wall thickness and attenuated echogenicity of the mucosa compatible with small bowel wall severe edema (asterisk).

Close modal
Figure 3

Case 6. Transverse ultrasound scan (right prefemoral access) of a stranded loggerhead (Caretta caretta) with no longline present but with a single hook in the oral cavity showing a linear formation in the wall of the intestine (empty arrow).

Figure 3

Case 6. Transverse ultrasound scan (right prefemoral access) of a stranded loggerhead (Caretta caretta) with no longline present but with a single hook in the oral cavity showing a linear formation in the wall of the intestine (empty arrow).

Close modal
Figure 4

Case 7. (a) Transverse ultrasound scan (right prefemoral access) of a stranded loggerhead (Caretta caretta) with a longline protruding from the oral cavity and a single hook in the intracoelomic esophagus. There is a laceration of an intestinal wall with leakage of the content into the coelomic cavity (empty arrow). (b) Intraoperative image: Highly hyperemic, bundled loops of small intestine, with lacerations of the wall and necrotic margins, from which a segment of line embedded in fibrinonecrotic matter was extracted.

Figure 4

Case 7. (a) Transverse ultrasound scan (right prefemoral access) of a stranded loggerhead (Caretta caretta) with a longline protruding from the oral cavity and a single hook in the intracoelomic esophagus. There is a laceration of an intestinal wall with leakage of the content into the coelomic cavity (empty arrow). (b) Intraoperative image: Highly hyperemic, bundled loops of small intestine, with lacerations of the wall and necrotic margins, from which a segment of line embedded in fibrinonecrotic matter was extracted.

Close modal
Figure 5

Case 2 (a) Transverse ultrasound scan (right prefemoral access) of a stranded loggerhead (Caretta caretta) with a longline protruding from the cloaca and a single hook in the cervical esophagus. There is evidence of an ileoterminal intussusception into the colon with a multilayering of the intussusceptum. (b) Intraoperative image showing an invagination of a loop extending for more than 40 cm in the ileum adjacent to the colon. The intussusceptum tract is completely lacerated along the mesenteric margin, with protrusion of the line from intestinal perforation.

Figure 5

Case 2 (a) Transverse ultrasound scan (right prefemoral access) of a stranded loggerhead (Caretta caretta) with a longline protruding from the cloaca and a single hook in the cervical esophagus. There is evidence of an ileoterminal intussusception into the colon with a multilayering of the intussusceptum. (b) Intraoperative image showing an invagination of a loop extending for more than 40 cm in the ileum adjacent to the colon. The intussusceptum tract is completely lacerated along the mesenteric margin, with protrusion of the line from intestinal perforation.

Close modal

Surgery was performed as soon as possible in all 37 loggerhead sea turtles to remove hooks (n=35), the fishing lines (n=2), or both the hook and the fishing lines (n=7). Cervical (30/37 loggerhead sea turtles) and supraplastron (5/7 loggerhead sea turtles) approaches to the esophagus were necessary for removal of hooks.

In the 24% (9/37) of loggerhead sea turtles with US evidence of long fishing line located inside (sometimes throughout) the intestine, a right inguinal incision into the coelomic cavity was performed through the soft tissues of the prefemoral fossa (Brannian et al. 1984; Gould et al. 1992; Di Bello et al. 2006a; Table 1). In seven turtles this inguinal approach to the coelom was required before removing hooks from the esophagus, via the corresponding approaches, because of the presence of fishing lines. In one animal, the same right inguinal approach was performed before removing a hook from the oral cavity. In these eight cases, it was necessary to proceed initially with single or multiple enterotomies to remove the line, thus reducing traction on the hook, which was subsequently extracted together with the remainder of the line. In one sea turtle with diagnostic evidence of hook fragments in the esophagus and colon, only the inguinal approach with enterotomies was performed. In two loggerhead sea turtles, besides multiple enterotomies it was necessary to perform an enterectomy because of bowel wall damage.

In all nine loggerhead sea turtles that underwent coeliotomy, the intestine was diffusely thickened with edema and hyperemia of the mucosa. Coeliotomy confirmed coelomic effusion in seven sea turtles. The fluid was transparent in three sea turtles and hemorrhagic in four other animals. Plication of the small intestine and colon along the mesenteric margin was present in seven animals (Fig. 1b). In one subject that had ingested a large caliber line, the intestine did not appear plicated, confirming the US finding in this sea turtle. The intestine was carefully inspected to check for perforations and necrosis, which were found in four animals (Fig. 4b). In one of those, there was a 40-cm intussusception of the ileum into the colon with multiple and extensive lacerations, serosal adhesions among the walls, and necrosis of the invaginated portions (Fig. 5b). Moreover, massive contamination of the coelomic cavity was found due to leakage of fecal material from intestinal lacerations.

Seven loggerhead sea turtles that underwent coeliotomy (Table 1) were released after 10- to 20-wk rehabilitation periods. Because of the serious condition of the intestine and poor clinical conditions, one turtle with intussusception underwent euthanasia. Another turtle that showed such severe bowel wall damage as to require extensive enterectomy died 3 d after surgery.

Loggerheads are among the most frequent victims of bycatch in drifting longlines (Lewison et al. 2004; Camiñas et al. 2006; Casale et al. 2008). The ingestion of fish hooks and fishing lines is one of the most frequent causes of death for sea turtles (Orós et al. 2005; Di Bello et al. 2006a). A study on sea turtles that were victims of drifting longlines in the Mediterranean demonstrated that the hook was embedded in the mouth in 36% of cases, the esophagus in 42% of cases, the stomach in 8% of cases, and the intestine in 6% of cases (Di Bello et al. 2013). Multiple hooks were observed in 5% of cases, lodging in the digestive tract in different locations, whilst in 3% of cases a line passed through the digestive tract but hooks were not identified (Di Bello et al. 2013).

At the time of the clinical observation, the presence and localization of the hook were easily observed during routine radiographic examinations. What is often missed, at least until surgical extraction of hooks that are wedged in the proximal portions of the digestive tract is attempted, is the possible presence of lengths of fishing line anchored to the hook, which may run along the intestinal canal.

More often than not, sea turtles entangled in a drifting longline are immediately thrown back into the sea by fishermen after cutting the fishing line. Unless the line is cut short, a few centimeters from the hook, the segment that emerges from the mouth may run back aborally and be ingested. Moreover, the line can follow the progression of the hook that has detached from the oral or esophageal mucosa, and the peristaltic movements will displace the line caudally. In such cases the line may occupy a part of the digestive tract or entirely pass through it and emerge from the cloaca, while the hook may then pierce the stomach or intestinal wall (Di Bello et al. 2013). This will result in traction, lacerations, necrosis, and invaginations of the walls of the intestine, and will ultimately cause the death of the animal.

In sea turtles hooked by longline gear, the presence of lines extending into the intestine should always be considered. This is sometimes quite evident because the line runs out through the cloaca but, even when the line runs out through the mouth, intestinal involvement cannot be excluded because the line may run back aborally and be ingested, forming a long loop. Even when the line runs out of the cloaca, making obvious its presence and the fact that it runs all through the intestinal tract, it is not possible to know what the conditions of the intestinal walls are like before surgical intervention. These may include severe lesions, perforations, necrosis, and variable degrees of plication of the bowel loops. It is difficult to ensure correct surgical decision-making and to make a prognosis without knowing about the state of the intestine and coelom.

As in other chelonian species, the carapace and plastron severely limit the examination of internal organs, and the diagnosis based only on a clinical examination is usually very poor. Furthermore, the presence of a foreign body or soft tissue opacity may easily be overlooked on a radiograph. When the radiographic diagnosis of a foreign body is uncertain, a gastrointestinal contrast study can be performed in sea turtles, but the diagnostic procedure is challenging (Di Bello et al. 2006b).

In humans and veterinary patients, ultrasonography has replaced the use of contrast studies in the evaluation of some gastrointestinal tract conditions (Tyrrell and Beck 2006). In sea turtles, much of intestine can be visualized through the left and right prefemoral windows. The ultrasonographic anatomy of the small intestine is similar to that of mammals with five wall layers visualized. In contrast, the wall of the large intestine is thinner and has indistinguishable layers (Pease et al. 2017)

In the current study, ultrasonography positively identified the foreign body in 89% (8/9) of loggerhead sea turtles. The presence of intestinal plication (in all nine loggerhead sea turtles) and ultrasonographic visualization of the linear foreign body was always consistent with the ingestion of a fishing line. In sea turtles, fishing lines cause a corrugated appearance in the small intestine due to increased/unproductive peristalsis. The affected small bowel loops are usually dilated with fluid.

The additional information obtained from ultrasonography can assist in surgical planning. In our study, US allowed us to make an important analysis of the characteristics, number, and severity of the bowel wall lesions in each animal, thus ensuring correct planning of the surgical procedure, including a correct approach for the surgical procedure. In addition, in one case the US identification of the fishing line, despite the fact that survey radiography had not revealed the presence of a hook, enabled us to remove the foreign body from the gut.

Ultrasonography provides specific information about alterations of the wall of the gastrointestinal tract, including viability. Symmetric thickening of the wall with preservation of the normal layering in the small intestine was shown in all loggerhead sea turtles. Intestinal perforation was sonographically suggested in two animals with no radiographic evidence of such lesions. This information promoted rapid surgical treatment of these animals. In the case of thicker (diameter 1.40–1.80 mm) fishing lines, the lesions observed were mostly edema and congestion of the intestinal walls while the most severe intestinal lesions were observed in subjects that had ingested thin (diameter: 0.60–0.80 mm) fishing lines (Di Bello et al. 2013). The value of US in the diagnosis of intestinal perforations with no presence of pneumocoelom on survey radiographs is noteworthy.

Ultrasound examination also facilitates the identification of intestinal lacerations or intussusceptions and allows for assessment of the nature and volume of coelomic fluid. Sonographic examination of the coelomic cavity detected free fluid in 78% (7/9) of animals and intussusception of the ileum into the colon in one. In cross-section, intussusception appears as a multiple-concentric-rings sign (a mass with multiple alternating hypoechoic and hyperechoic concentric rings), which represent the multiple intestinal wall layers of the intussuscipiens within the intussusceptum.

There are many advantages of ultrasonography because it provides real-time imaging. When selecting an imaging modality, a balance of the imaging need, capital cost, equipment availability, and patient accessibility should be taken into account as well as the best modality to identify the abnormality suspected (Pease et al. 2017).

The findings of our study suggested that US examination of the coelomic cavity is a key diagnostic tool that should be complementary to radiographic survey when accidental ingestion of fishing hooks and fishing lines is suspected in sea turtles. Through the left and right inguinal acoustic windows, it is possible to visualize the entire intestinal canal and check for the presence of lines, as well as alterations to the wall of the gastrointestinal tract, gaining additional information including motility, lacerations, necrosis, and the degree of intestinal plication, which is invaluable to optimize the surgical decision making.

Aguilar
R,
Mas
J,
Pastor
X.
1995
.
Impact of Spanish swordfish longline fisheries on the loggerhead sea turtle Caretta caretta population in the western Mediterranean
.
In
:
Proceedings of the 12th annual workshop on sea turtle biology and conservation
,
Richardson JL, Richardson TH, compilers. National Oceanic and Atmospheric Administration Technical Memorandum NMFS-SEFSC-361. US Department of Commerce, National Oceanographic and Atmospheric Administration, National Marine Fisheries Service, Southeast Fisheries Science Center, Miami, Florida,
pp
.
1
6
.
Bjorndal
KA,
Bolten
AB,
Lagueux
CJ.
1994
.
Ingestion of marine debris by juvenile sea turtles in coastal Florida habitats
.
Marine Poll Bull
28
:
154
158
.
Brannian
RE.
1984
.
A soft tissue laparotomy technique in turtles
.
J Am Vet Med Assoc
185
:
1416
1417
.
Camiñas
JA,
Báez
JC,
Valeiras
X,
Real
R.
2006
.
Differential loggerhead by-catch and direct mortality due to surface longline according to boat strata and gear type
.
Sci Mar
70
:
661
665
.
Casale
P,
Cattarino
L,
Freggi
D,
Rocco
M,
Argano
R.
2007
.
Incidental catch of marine turtles by Italian trawlers and longliners in the central Mediterranean
.
Aquat Conserv
7
:
686
701
.
Casale
P,
Freggi
D,
Rocco
M.
2008
.
Mortality induced by drifting longline hooks and branchlines in loggerhead sea turtles, estimated through observation in captivity
.
Aquat Conserv
18
:
945
954
.
De Majo
M,
Macri
F,
Masucci
M,
Cogi
G,
Pennisi
MG.
2016
.
Clinical ultrasonography in loggerhead sea turtles (Caretta caretta): Imaging of pathological features
.
Vet Med-Czech
61
:
155
161
.
Di Bello
A,
Valastro
C,
Freggi
D,
Lai
OR,
Crescenzo
G,
Franchini
D.
2013
.
Surgical treatment of injuries caused by fishing gear in the intracoelomic digestive tract of sea turtles
.
Dis Aquat Organ
106
:
93
102
.
Di Bello
A,
Valastro
C,
Staffieri
F.
2006a
.
Surgical approach to the coelomic cavity through the axillary and inguinal regions in sea turtles
.
J Am Vet Med Assoc
228
:
922
925
.
Di Bello
A,
Valastro
C,
Staffieri
F,
Crovace
A.
2006b
.
Contrast radiography of the gastrointestinal tract in sea turtles
.
Vet Radiol Ultrasound
47
:
351
354
.
George
RH.
1997
.
Health problems and diseases of sea turtles
.
In
:
The biology of sea turtles
,
Lutz
PL,
Musick
JA,
editors
.
CRC Press
,
Boca Raton, Florida
,
pp
.
363
386
.
Glazebrook
JS,
Campbell
RS,
Blair
D.
1989
.
Studies on cardiovascular fluke (Digenea: Spirorchiidae) infections in sea turtles from the Great Barrier Reef, Queensland, Australia
.
J Comp Pathol
101
:
231
250
.
Gordon
AN,
Kelly
WR,
Lester
RJ.
1993
.
Epizootic mortality of free-living green turtles, Chelonia mydas, due to coccidiosis
.
J Wildl Dis
29
:
490
494
.
Gould
WJ,
Yaegar
AE,
Glennon
JC.
1992
.
Surgical correction of an intestinal obstruction in a turtle
.
J Am Vet Med Assoc
200
:
705
706
.
Hasbún
CR,
Lawrence
AJ,
Samour
JH,
Al-Ghais
S.
1998
.
Duodenal volvulus in free-living green turtles from coastal United Arab Emirates
.
J Wildl Dis
34
:
797
800
.
Hays
GC,
Åkesson
S,
Broderick
AC,
Glen
F,
Godley
BJ,
Papi
F,
Luschi
P.
2003
.
Island-finding ability of marine turtles
.
Proc Biol Sci
270
(
1 Suppl
):
S5
S7
.
Lewison
RL,
Crowder
LB.
2007
.
Putting longline bycatch of sea turtles into perspective
.
Conserv Biol
21
:
79
86
.
Lewison
RL,
Freeman
SA,
Crowder
LB.
2004
.
Quantifying the effects of fisheries on threatened species: The impact of pelagic longlines on loggerhead and leatherback sea turtles
.
Ecol Lett
7
:
221
231
.
Martorell
J,
Espada
Y,
De Gopegui
RR.
2004
.
Normal echoanatomy of the red-eared slider terrapin (Trachemys scripta elegans)
.
Vet Rec
155
:
417
420
.
Orós
J,
Calabuig
P,
Déniz
S.
2004
.
Digestive pathology of sea turtles stranded in the Canary Islands between 1993 and 2001
.
Vet Rec
155
:
169
174
.
Orós
J,
Torrent
A,
Calabuig
P,
Déniz
S.
2005
.
Diseases and causes of mortality among sea turtles stranded in the Canary Islands, Spain (1998–2001)
.
Dis Aquat Organ
63
:
13
24
.
Pease
A,
Blanvillain
G,
Rostal
D,
Owens
D,
Segars
A.
2010
.
Ultrasound imaging of the inguinal region on adult male loggerhead sea turtles (Caretta caretta)
.
J Zoo Wildl Med
41
:
69
76
.
Pease
A,
Di Bello
A,
Rivera
S,
Valente
ALS.
2017
.
Diagnostic imaging
.
In
:
Sea turtle health & rehabilitation
,
Manire
CA,
Norton
TM,
Stacy
BA,
editors
.
J. Ross Publishing
,
Plantation, Florida
,
pp
.
123
143
.
Peckham
SH,
Diaz
DM,
Walli
A,
Ruiz
G,
Crowder
LB,
Nichols
WJ.
2007
.
Small-scale fisheries bycatch jeopardizes endangered Pacific loggerhead turtles
.
PLoS One
2
:
e1041
.
Ryder
CE,
Conant
TA,
Schroeder
BA.
2006
.
Report of the workshop on marine turtle longline post-interaction mortality
.
National Oceanic and Atmospheric Administration Technical Memorandum NMFS-F/OPR-29
.
US Department of Commerce
,
Washington, DC
, 36 pp.
.
Schumacher
J,
Toal
RL.
2001
.
Advanced radiography and ultrasonography in reptiles
.
Sem Avian Exotic Pet Med
10
:
162
168
.
Tomás
J,
Gozalbes
P,
Raga
JA,
Godley
BJ.
2008
.
Bycatch of loggerhead sea turtles: Insights from 14 years of stranding data
.
Endang Species Res
5
:
161
169
.
Tyrrell
D,
Beck
C.
2006
.
Survey of radiography vs. ultrasonography in the investigation of gastrointestinal foreign bodies in small animals
.
Vet Radiol Ultrasound
47
:
404
408
.
Valente
AL,
Parga
ML,
Espada
Y,
Lavin
S,
Alegre
F,
Marco
I,
Cuenca
R.
2007
.
Ultrasonographic imaging of loggerhead sea turtles (Caretta caretta)
.
Vet Rec
161
:
226
232
.
Williams
SR,
Dennison
S,
Dunnigan
B,
Moore
B,
Nicholson
J,
Zagzebski
K,
Ketten
D,
Cramer
S,
Arruda
J.
2013
.
Diagnosis and management of intestinal partial obstruction in a loggerhead turtle (Caretta caretta)
.
J Zoo Wildl Med
44
:
457
461
.