Common reproductive conditions of the reptile include prolapse of the cloaca, oviduct or copulatory organ, yolk coelomitis, dystocia or egg binding, as well as follicular stasis (Fig 1).
- In follicular stasis, also known as pre-ovulatory egg binding, retained follicles fail to involute or regress. If the follicles persist long enough, they become necrotic and inspissated, which can lead to yolk coelomitis. Follicular stasis is commonly reported in captive lizards like iguanas and water dragons. This condition also occurs in chelonians (turtles and tortoises) but is rare in snakes.
- The terms dystocia, egg retention, and post-ovulatory egg binding are often used interchangeably. Technically, egg retention or egg binding is a failure to lay eggs as expected based on breeding history. Dystocia refers to difficulty in oviposition or egg laying. Unfortunatelyegg retention and dystocia are relatively common in captive reptiles. In a survey of multiple facilities with a total of 1600 reptiles, dystocia occurred in approximately 10% of animals (Lloyd 1990).
1. Clinical signs of dystocia or egg binding are non-specific
Clinical signs of dystocia or egg binding in the reptile are non-specific and can vary widely. Retained eggs can remain within the uterus well beyond the normal period of time without causing obvious clinical signs of pathology, however chronic egg retention can lead to debilitation (Box 1) caused by salpingitis or even oviductal rupture with secondary coelomitis.
Box 1. Clinical signs of dystocia or egg binding in reptiles
A common presentation in snakes is failure to lay a full clutch (or collection of eggs) after a history of recent oviposition or egg laying. The retained eggs, frequently called “slugs” in snakes, are visible as caudal masses in many snakes. Coelomic palpation is necessary in larger species like pythons.
There is also a recent report of repeated scratching in the direction of the cloaca in a red-eared slider turtle (Trachemys scripta elegans) with oviductal disease (Mans 2012).
2. The most obvious difference between a gravid lizard one in dystocia
The most obvious difference between a gravid lizard and one in dystocia is often attitude. The distinction between a normal gravid lizard and one suffering from follicular stasis or dystocia can be subtle. Anorexia is normal in the gravid lizard, which can produce dozens of eggs that completely fill the coelom. The normal female often stops eating approximately 1 to 4 weeks before egg laying. Some weight loss and loss of some body condition is to be expected, however the gravid female is alert, aware, and relatively active. The female in follicular stasis or dystocia may be lethargic, persistently anorectic, and possibly emaciated.
3. Reproductively-active females with marginal calcium stores often develop signs of hypocalcemia
Normal reproductive activity places high demands on body calcium stores. Therefore females provided with borderline diets and husbandry that have only marginal calcium levels often develop signs of calcium deficiency.
Hypocalcemia is most commonly observed in herbivorous and insectivorus lizard species like the green iguana. Rapid depletion of calcium can lead to paresis, tremors, muscle fasiculations, tetany, and seizures. Profound mobilization of bone calcium can even cause lameness and deformation of the mandibles in rare instances.
Management of calcium deficiency is similar to that used in nutritional secondary hyperparathyroidism or metabolic bone disease (Box 2).
Box 2. Management of the hypocalcemic female reptile
|*Use caution with parenteral calcium administration as concurrent hyperphosphatemia can predispose the patient to soft tissue mineralization. Switch to oral calcium when the gut appears to work. Slow bolus intravenous or intraosseous calcium administration is typically reserved for tetany.IM: intramuscular; IC: intracoelomic; IV: intravenous; IO: intraosseous; PO: per os|
|Strict cage rest||Provide an appropriate temperature gradient and humidity level.|
|Provide supportive care, manage gastrointestinal ileus|
|Vitamin D (optional)||1000 IU/kg IM once weekly|
|Nutritional support||Begin enteral nutritional support as soon as paresis improves|
|Client education||Discussion correction of husbandry with the owner (they can work on correcting home setup while you provide inpatient care)|
|Manage reproductive disease||Put to an end whatever reproductive activity led to calcium depletion (see #7-9 below)|
4. Inadequate nesting is an important cause of egg retention in lizards
Lack of an adequate nesting site is an important cause of egg retention in lizards, particularly green iguanas (Iguana iguana). Many reptiles use an ‘ovipositrium’ or lay box (Box 3). In fact, failure to provide a proper nesting site can lead to dystocia in an otherwise healthy female.
Box 3. Features of an appropriate* lay box
|*These are general guidelines only as each species has specific requirements that can vary.|
In the wild, gravid iguanas exhibit extensive nesting behavior that includes migration to a suitable nest site and digging a relatively deep nest for the eggs. It is difficult, if not impossible, to duplicate these conditions in captivity. At minimum, provide the gravid iguana with a large lay box containing at least 1 to 2 feet (30 to 60 cm) of substrate.
An inadequate nest is not the only environmental issue that causes dystocia, many cases of egg binding or dystocia are believed to husbandry-related in captive reptiles (Box 4).
Box 4. Causes of egg binding or dystocia in captive reptiles
Obstructive dystocia can be caused by fetal or maternal abnormalities ranging from an oversized, malformed, or misshapen eggs or fetus, deformed pelvis, oviductal stricture, as well as mass lesions like a granuloma or tumor within the oviduct, urolithiasis, cloacolith, fecal impaction, or gastrointestinal foreign body.
5. Distinguishing normal and retained eggs can be difficult
Since the normal female can retain eggs for an extended period, distinguishing normal eggs from retained eggs can be difficult. The diagnosis of egg retention or dystocia requires careful evaluation of the patient husbandry and reproductive history (see #2 above). Often a thorough diagnostic workup is also required.
Use a complete blood count and plasma biochemical analysis to evaluate your patient’s overall health status (Box 5). The reproductively active female should display a significant hypercalcemia, which is a normal physiologic response associated with calcium mobilization. Measurement of ionized calcium can also prove helpful. Ionized calcium levels were reported to be 1.47 +/- 0.105 mmol/L in normal green iguanas (Dennis 2001).
Box 5. Reported laboratory results in select reproductive diseases of reptiles
Survey radiographs are also useful to identify follicles or to assess the number, size, shape, and degree of calcification of the eggs. As a general rule, follicles tend to be round in shape and arranged like a large cluster of grapes as they extend off of the ovary. Shelled eggs tend to be more ovoid and more evenly spaced throughout the coelom. A thin, delicate shell may also be visible (Box 6).
Box 6. Follicles versus eggs on survey radiographs
|Shelled egg||Oval||More evenly distributed throughout the coelom|
Ultrasonography and endoscopy can also provide valuable information and help identify underlying disease that can cause egg retention or dystocia.
6. Beware egg manipulation
Beware: Egg manipulation is a popular method of egg removal among snake hobbyists. Physical manipulation of the egg involves palpation or “milking” of eggs by firmly running a finger down the snake’s ventrum. Although tempting, this technique carries significant risk since the distended, often friable oviduct can rupture or prolapse potentially leading to bacterial or yolk coelomitis and even death.
If physical manipulation is attempted in a clinical setting, select snake patients with non-obstructive dystocia. Gently manipulate the egg towards the cloaca; never force the egg.The risk of adverse effects is also significantly reduced when the patient is under general anesthesia so physical manipulation is frequently attempted prior to surgical correction of dystocia or egg binding.
7. Medical management of dystocia or egg binding
Medical management of dystocia or egg binding frequently relies upon hormonal stimulation, supplemental calcium as needed, and supportive care including fluids. Stabilize and rehydrate the patient. Provide a suitable nesting area with the proper heat and humidity levels for that species. Some early cases of egg retention may respond to this step alone.
Stimulate contractions of the oviduct:
- Oxytocin (5-30 IU/kg IM, Bimeda Animal Health Inc., LeSueur, MN USA) is often effective in chelonians with egg retention or non-obstructive dystocia. In fact, doses as low as 1 IU/kg have been effective in tortoises (Glassford 1977). Squamates (lizards and snakes) do not respond as consistently to oxytocin (Denardo 2006, Rivera 2008). Oxytocin can be administered every 20 to 60 minutes for 2 to 3 treatments, at least 60 minutes after the administration of parenteral calcium (see calcium below).Like birds, reptiles are much more sensitive to arginine vasotocin (0.01-1 ug/kg IV or IC), however this agent is only available in research settings.
- Although oxytocin promotes oviductal contractions, calcium levels must be adequate. Administer calcium gluconate (50-100 mg/kg IC, IM, SC, American Pharmaceutical Partners, Inc., Schaumburg, IL USA) when indicated at least 60 minutes before oxytocin administration.
- Beta-blockers, such as propranolol (1 ug/kg IC)or atenolol (7 mg/kg PO), have been reported to potentiate the effects of oxytocin in some chelonians and lizards.
Prostaglandins have also been tried for dystocia in reptiles. A combination of oxytocin (7.5 IU/kg) and PGF2 alpha (1.5 mg/kg SC) was reported to be effective in inducing oviposition in red-eared sliders (Sykes 2010).
McArthur (2004) has recommended a protocol for dystocia in the reptile that involves lubrication of the cloaca and administration of calcium (as needed). These treatments are then followed by atenolol (7 mg/kg PO) and oxytocin (1-3 IU/kg IM) 8-12 hours later.
If medical treatment fails, an experienced reptile veterinarian can perform further diagnostics, such as endoscopy or exploratory coeliotomy.
8. Ovocentesis techniques
Ovocentesis isn’t just for the birds: Transcloacal and percutaneous ovocentesis techniques have been described in reptiles. The goal of ovocentesis is to make the egg(s) smaller and therefore easier to pass (Box 7).
Box 7. Transcloacal ovocentesis
9. Surgical management of dystocia or egg binding
Surgical management of dystocia or egg binding should be performed by an experienced reptile veterinarian when there is no response to medical treatment or the reptile suffers from obstructive dystocia. Ovariectomy is the treatment of choice for follicular stasis. Management of egg binding or dystocia will vary with the species involved and the condition of the oviducts. Single or multiple salpingotomy may be performed in snakes, while unilateral or bilateral salpingectomy or ovariosalpingectomy is performed in snakes or lizards. Bilateral procedures are typically performed in lizards. Dystocia can usually be resolved with improvements in husbandry or medical therapy in chelonians, however surgery can be performed via prefemoral celiotomy, plastron osteotomy, or by endoscopic-assisted prefemoral approach.
10. Dystocia in reptiles is not usually an emergency situation except…
Dystocia is not usually an emergency situation in reptiles although delays in treatment increase the risk of complication. There are two exceptions to this rule of thumb. First, screen all patients with reproductive disease for the presence of bacterial or yolk coelomitis since this requires immediate treatment (see #11 below). Also lizards with retained eggs can quickly become depressed and unresponsive so treatment is rarely delayed.
In contrast, dystocia can usually be resolved with improvements in husbandry or medical therapy in chelonians, and is rarely considered a medical emergency.
Snakes can tolerate dystocia for extended periods of time, however pressure from the retained egg(s) can cause local inflammation. In patients that lay egg(s) then halt delivery, Denardo (2006) recommends that treatment be initiated within 48 hours, because as he says “The female sometimes completes delivery during first 48h but rarely after this time”.
11. Yolk peritonitis is common
Yolk peritonitis or coelomitis is one of the most common diseases of the reptile reproductive tract. Egg yolk coelomitis is one of the most common diseases of the reproductive tract and an important cause of death in captive lizards such as iguanas and bearded dragons (Pogona vitticeps). In lizards, yolk coelomitis can occur secondary to retained follicles, oophoritis, salpingitis, or dystocia. Except for iatrogenic coelomitis caused by overzealous egg manipulation (see #6 above), yolk peritonitis is not very common in snakes.
Unlike many reptile health problems, patients with coelomitis can rapidly decline. Clinical signs are often non-specific and can include anorexia, lethargy, diarrhea, reduced or absent fecal output, and apparent discomfort upon coelomic palpation.
Laboratory results can include hypercalcemia, hyperproteinemia, anemia and/or azotemia, leukocytosis, and azurophilia. A definitive diagnosis of egg yolk coelomitis relies on ultrasonographic identification of coelomic fluid, as well as aspiration and analysis of the material collected. Other imaging modalities, such as endoscopy and radiography, can aid in diagnosis as well identifying the underlying cause of follicular stasis or dystocia.
After stabilizing the debilitated patient with supportive care, an exploratory celiotomy is performed to remove yolk material and thoroughly lavage the coelom. Care should be taken to pack the cranial aspect of the incision to avoid spreading contaminated material cranially. Bilateral ovariectomy is also be required in many cases. Patients are provided with analgesia and started on antibiotics. Supportive care must be continued postoperatively since patients are often severely compromised.
12. Prolapse is a common clinical problem
Prolapse is a common clinical problem in male and female reptiles. Cloacal prolapse can occur during normal oviposition or with dystocia and is often associated with poor management or with disease processes that promote tenesmus. Keep prolapsed tissues moist until they can be cleaned gently.Use cold compresses or hypertonic solutions like 50% dextrose or hypertonic saline to shrink edematous tissues. Then carefully and gently Invert and return prolapsed tissue using a relatively large diameter, blunt instrument like a rubber catheter, syringe case, or sexing probe. Management of cloacal prolapse should almost always be performed under sedation or general anesthesia.
Oviductal prolapse is another common sequela to dystocia, particularly in snakes. Mild oviductal prolapses can be reduced transcloacally. More severe prolapses require a surgical approach. Traumatized tissue may need to be removed, however if this is necessary then ovariectomy on the same side should also be recommended to reduce to risk of yolk coelomitis.
Prolapse of the phallus or penis:Prolapse of the phallus in chelonians or hemipenis in snakes and lizards is usually the result of infection and inflammation secondary to trauma (aggressive sex probing), chronic sexual activity, excessive straining caused by disease of the lower urogenital or gastrointestinal tract (i.e. constipation, endoparasite, foreign body, cystic calculi). Prolapse can also be associated with neurologic dysfunction or general debilitation in all reptiles or even metabolic bone in chelonians (Martinez-Jiminez 2007, Innis 2002). A normal chelonian phallus can become turgid during cloacal manipulation or handling of the caudal shell, but the phallus should retract within a few hours (Innis 2002).
Prolapsed copulatory organs quickly become traumatized and swollen, making reduction near impossible. Fortunately the urinary system is separate from phallus since the ureters empty into the cloaca. In some cases, after irrigating the prolapsed tissue, lubrication and occlusive bandaging can be applied overnight while the patient is stabilized for surgery and anesthesia the next day (Martinez-Jiminez 2007).
- In small chelonians, the base of the phallus can be ligated with transfixing, circumferential, or vertical mattress patterns with absorbable suture. The phallus is then transected and removed (Innis 2002).
- Lateral vessels as well as each corpus cavernosum should be ligated separately in larger chelonians. The phallus is then dissected free of cloaca and cut.
- Make sure the prolapsed lizard or snake hemipenis is fully everted. Then clamp and ligate at the base, using a horizontal mattress pattern again with absorbable suture . Transect and remove the prolapsed tissue, then replace the stump into the tail base.
- Some surgeons recommend placement of a stay suture like a purse string suture for 2 to 3 weeks (Sykes 2010), some do not (Denardo 2006).
Be sure to provide appropriate antimicrobial and analgesic therapy, and do not forget to look for the underlying cause of prolapse.
The prognosis for reproductive tract disease in reptiles tends to be good as long as the patient was originally in good health.
Educate owners on proper husbandry, since optimal temperature, humidity, and nutrition as well as the need for appropriate nest box for sexually mature females. Currently the only clinical prevention to reproductive disease that veterinarians can offer is bilateral ovariosalpingectomy or ovariectomy.