Abstract: Two unrelated iguanas were diagnosed with unilateral ovarian torsion based on gross and microscopic findings. Case 1 was an adult female green iguana that died of severe egg retention and systemic bacterial infection, accompanied by unilateral granulomatous oophoritis and 360° clockwise torsion of the left ovary. Case 2 was a 2-year-old female rhinoceros iguana who died after a 7-day history of marked weakness, lethargy, anorexia, and tremors. The right ovary showed 270° counterclockwise torsion, accompanied by oophoritis and body cavity effusion. This is believed to be the first report of ovarian torsion in an iguana, although follicular torsion was recently documented in a green iguana.

Keywords: Rhinoceros Iguana , green iguana, egg retention, oophoritis, ovarian torsion.

Ovarian torsion has been rarely described in animals, mainly horses (Sedrish et al., 1997; Valk et al., 1998). In reptiles, a case of follicular torsion was recently documented in an iguana (Mehler et al., 2002). In females, ovarian torsion is often associated with underlying ovarian disease or pregnancy (Cass 2005, Majhi et al. 2005, Schultz et al. 2005). This report documents ovarian torsion in two unrelated captive iguanas.

01 Case 1

A captive 1.9 kg adult female green iguana from a mixed population of 20 iguanas was submitted for necropsy. It was also found dead, without warning, a day after two other iguanas in the same group succumbed to systemic bacterial infections. The animals were housed in a 4*4*1-2.5 meter indoor enclosure consisting of wooden walls and a concrete roof. The bedding material consists of wood chips. Temperature range is 20-26°C (68-79°F), using artificial UV lamp. The diet consisted of fruits, vegetables, dry iguana food (diet Monster Adult iguana, Orbis), boiled eggs, and vitamin supplements (Nekton iguana). Iguanas undergo routine veterinary examinations once a year and are checked daily by keepers. At necropsy, the iguana showed severe and diffuse atrophy of adipose tissue and moderate atrophy of skeletal muscle. The body cavity was moderately to severely dilated as the bilateral fallopian tubes retained a large number of eggs with calcified shells. There was also a small amount of red serous fluid in the body cavity, and there were fibrin chains on the serosa of the gastrointestinal tract and right fallopian tube. The right fallopian tube contained numerous degenerated and partially dehydrated eggs (Figure 1-1), some of which were multifocally adherent to the mucosa, consistent with areas of ulceration and necrosis, and were covered with yellow exudate. The left ovary was twisted 360° clockwise and consisted of a 4 x 3.8 x 3 cm mass. No normal follicle structure could be seen on the outside (Figure 1-1 and Figure 1-2), and there was a slightly higher white large area on the surface. Extends into the underlying ovarian stroma. Superficial blood vessels are obviously congested. After incision, the ovarian stroma was dark red and necrotic. There were two necrotic follicles in the lesion, 2 cm in diameter, and the yolk was dense, concentrated and hard. The twisted ovarian vascular rod was compressed between the left ovary and adrenal gland and was generally normal. The right adrenal gland and ovary were also essentially normal. There are some yellow nodules up to 1 mm in diameter in the liver and heart. There is a small amount of mucus and many ulcers in the stomach, and the red halo is up to 2 mm in diameter. The gallbladder is moderately dilated and the bile is basically normal. There was a 2 cm mass in the caudal third, consisting of a large necrotic focus with a large amount of yellow dry exudate forming concentric bands covering the vertebrae within the lesion and extending into adjacent skeletal muscle and subcutaneous organize.

Green iguana, case 1. Note bilateral severe egg retention, egg degeneration (de), and marked enlargement (asterisk) of the left ovary compared with the normal right ovary (arrow); gb = gallbladder. Bar=1 cm.

Left ovary; green iguana, iguanas, case 1. The distorted ovary is seen to be significantly enlarged with loss of extracystic follicular structure and a large white patch on the surface (asterisk). Bar=1 cm.

Left ovary; green iguana, case 1. The distorted section of the ovary shows obvious congestion, thickening and necrosis of the ovarian stroma (asterisk), as well as necrosis of the follicle wall (nf) and thickening of the yolk (iy). The concentrated yolk is removed from another follicle. Bar=1 cm.

Under the microscope, there were obvious dilated blood vessels in the left ovary, some of which had fibrin thrombi. There was diffuse necrosis of the ovarian stroma and follicles, the white superficial lesion described was mainly composed of sheets of macrophages, coccal colonies were mainly located at the advancing edge of the lesion, and the two ovarian lesions overlapped. The right ovary was histologically within normal limits. The right fallopian tube lesion consisted of a large area of ​​fibrinonecrosalpingitis with similar bacterial colonies within the lesion; they extended into the muscle fascicles multiple times and were accompanied by some histiocytic granulomas with small necrotic centers. Tail lesions include severe chronic granulomatous and necrotizing osteomyelitis with cocci within the lesions. In the adrenal gland, the interrenal cells are moderately hyperplastic with clear cytoplasmic vacuoles, some of which displace and compress the nucleus to the periphery. The gastric lesions consist of ulcers covered with abundant fungal organisms that match morphologically Candida and blasting conidia. Other lesions were mild focal chronic granulomatous and necrotizing hepatitis, moderate focal fibrinonecrotic and purulent mural endocarditis and myocarditis, and mild acute multifocal rhabdomyositis.

Left ovary; green iguana, iguana, case No.1 ovarian stroma was obviously congested, fibrin formation (t), necrotic stroma (ns) and follicles (nf) HE. Bar=1 mm

Left ovary ; Green iguana, case 1 shows hyperemia (asterisk) and ovarian stromal necrosis (ns), as well as subcapsular granulomatous inflammation (separated by thick arrows), with colonies at the advancing edge of the lesion (thin arrows). Hematoxylin and eosin. Bar=10mm.

After diagnosis of egg retention, it is recommended to evaluate the adequacy of the egg-laying bedding in the housing environment. Beach sand was placed in a corner of the enclosure and several more females quickly laid eggs.

02 Case 2

A two-year-old female rhino iguana presented with a two-day history of significant weakness, lethargy, anorexia, and tremors. He was fed dark leafy greens, fruit and the occasional monkey biscuit and housed in a 0.9 x 0.9 x 1.2m enclosure with UVB and heat lamps. Hematological examination showed leukocytosis (20,900/ml) and mild anemia (PCV23%) due to heterophilia (16,300/ml). Plasma biochemistry revealed only mild hypoalbuminemia and hypoalbuminemia (total protein 55 g/L or 5.5 g/dL, albumin 16 g/L or 1.6 g/dL); other values ​​were within normal limits ( Glucose 10.9 mmol/L or 198 mg/L, AST 16 U/L, calcium 2.73 mmol/L or 10.9 mg/d, phosphorus 1.8 mmol/L or 5.5 mg/dL, CK 638 IU/L, uric acid 26 μmol/L or 4.3 mg/dL). X-ray radiography revealed a small metallic foreign body in the gastrointestinal tract, but heavy metal analysis was apparently normal (lead <1.4 μg/dL, zinc 0.4 ppm). Through body cavity ultrasonography, multiple mixed echogenic nodules about 2.5 cm in diameter were found in the tail of the liver, which may correspond to eggs. We observed much smaller cystic structures in the near cranial extent of the presumed egg, which are thought to be small follicles. Electromyography showed no neuromuscular abnormalities. Treated with ceftazidime 20 mg/kg IM Q 72 hours, EDTA calcium 30 mg IM Q 24 hours, LRS and normal saline mixture, 30 ml/kg intraperitoneal injection and nutritional support, Aibao critical care powder, 20 mls SID, but in He was found dead 5 days after treatment.

At the time of autopsy, approximately 75 ml of serum red blood cell-modified exudate was collected in the body cavity (Figure 1-6). The right ovarian stalk was twisted 270° counterclockwise, the external follicle structure of the affected ovary was significantly enlarged and lost (Figure 1-6 and Figure 1-7), and the capsule was congested; the follicles were concentrated and adhered to the incarcerated part of the ovary. A black identifying clip was found in the cecal lumen. Aerobic culture of incarcerated yolk material from the right ovary yielded mild growth of enterococci.

Rhinoceros iguana, case 2. Note the body cavity fluid (asterisk) and the marked enlargement and loss of follicular structures outside the right ovary (ro); gb = gallbladder, li = liver. Bar=2 cm.

Rhino-horned iguana, case 2. Note the torsion of the right ovarian stalk (arrow); gb=gallbladder, Bar=2 cm.

Histologically, the right ovary showed congestion, hemorrhage, and follicular degeneration, accompanied by granulomas and heterophilic inflammation. Diffuse capsular congestion and localized diffuse red blood cell extravasation. Other associated microscopic findings include mild systemic soft tissue mineralization (renal tubules, mucocutaneous membranes, and large vessels), mild diffuse interstitial pneumonitis, and mild erythrophagocytosis of melanocytic macrophage centers in the liver.

Unilateral ovarian torsion was diagnosed based on pathological results. This is believed to be the first report of ovarian torsion in an iguana and in any reptile, although follicular torsion in green iguanas has been recently documented (Mehler, et al, 2002).

Ovarian torsion has been described in females, both as young adults and as adults (Sah et al., 2004, Cas, 2005, Majhi et al., 2005, and Schultz et al., 2005) . In the veterinary literature, there are a few reports of ovarian torsion in horses, including a mare with an underlying ovarian tumor (Sedrish et al., 1997) and a newborn foal (Valk et al., 1998 ).

Ovarian torsion in green iguanas is associated with underlying ovarian disease (bacterial oophoritis) and egg retention. Bacterial oophoritis, severe egg retention, and social stress caused by cagemate aggression may be causes of ovarian torsion. Rhinoceros iguanas also have potential for ovarian inflammation. In humans, ovarian torsion is often associated with underlying ovarian disease, such as ovarian tumors and dermoid cysts in pediatric cases (Sah et al. 2004, Cas 2005, Majhi et al. 2005, Schultz et al. 2005), has also been associated with pregnancy and ovarian hyperstimulation syndrome in adult-onset cases (Born et al, 2004) and rarely in cases of non-reproductive disease such as appendicitis (Hoey et al, 2005) or in the absence of independent ovarian disease middle.