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Medical and Surgical Treatment of Pre-ovulatory Ova
Stasis and Post-ovulatory Egg Stasis in Oviparous
Lizards
Stephen John
ivers, B.Se. (Hons),
.Biol.,M.I.Biol.,B.Vet.Med.,M.R.
.S.
Elands Veterinary Clinic, Station Road, Dunton Green, Sevenoaks, Kent TN13 2XA. United Kingdom
Tel (4) 1732452333 Fax (44) 1732 741614
Key words: squamata, sauria, dystocia, egg binding, calcium, oxytocin, fluid therapy,
anesthesia, propofol, isoflurane, surgery, ovariosalpingectomy
INTR DU TION
Lizards (Order Squamata, suborder Sauna) form a major part of the reptile pet trade with certain
species, notably the green iguana (Iguana iguana), beards ragon (Pagana vitticeps) and leopard
gecko (Eublepharus macularius) to name but a few, being particularly common. The increasing
number of lizards being kept and bred in captivity has lead to an increase obstetric cases being
presented to the veterinary clinician. This paper describes the medical and surgical approaches to
pre-ovulatory ova stasis and post...ovulatory egg stasis in oviparous species.
Reproductive physiology
Our understanding of reptile reproductive physiology still remains in its infancy, but several modem
texts are now avails
to the clinician 1,2,3. Lizards, like other reptiles, become sex Iy mature as
a consequence of size and less importantly age, and t refore in captivity many IiZ8f! become
reproductively active at a earlier age than sir wild counterparts. Under optimal conditions, small
lizards generally become sexually mature at 1-2 yr and larger species at 3-4 yr.
Most species of lizards may be stimulated to reproduce by hibernation (temperate species), changes
in night time temperature (tropicallsu ropical species), photoperiod, nutrition, humidity and social
gro ·ng. In a suitable environment t female will enter a cycle of vitellogenesis and folliculogenesis
under the hormonal control
estrogen 1• The ovaries become active and follicles
velop into
yolk-like ova. In the wild, environmental, behavioral and social cues coupled with hormonal
influences result in successful ovulation wi the ova passing into the oviducts for fertilization,
shelling and further egg development. In captivity, many females are kept singly or with an
incompatible male or within an inappropriate social group and for reasons largely unknown or poorly
understood the normal process of ovulation or egg deposition fails to take place.
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CASE PRESENTATION AND HISTORY
The environmental cues responsible for reprodudion often leads to affected lizards presenting in the
spring and summer, although tropical lizards may present at any time of year. The history can be
variable but usually indudes a period of prolonged hypophagia or anorexia. The owner may not have
seen any signs of courtship or copulation, indeed many female lizards (especially green iguanas)
may n have had any contact with a male lizard at all. The female may have been previously
hyperactive (nest site searching) or lethargic (debilitation). One or more shelled eggs may have been
passed but deposited in an inappropriate site such as a water bowl.
Lizards often present in a state of cachexia with sloss of muscle tissue around the pelvic girdle,
limbs and tail base. Abdominal enlargement is often obvious, although some owners mistake this
as an indication of good bodily condition. Gentle palpation may give an impression of multiple
c;oelomic masses suggestive of retained eggs. Sunken eyes,
eased skin elasticity and lethargy
are often present and should alert the clinician to the possibility of dehydration and infection.
Medical investigation
The first objedive must be to stabilize a severely compromised patient. A heparinized blood sample,
most easily collected from the ventral tail vein, is clinically very valuable and should be taken prior
to any treatment. A minimum clinicopathological data base includes packed cell volume,
semi...quantitative assessment of the buffy coat and blood smear, total protein, albumin, globulin,
calcium, phosphorus and uric acid. These tests should be well within the realms of an in-house
practice laboratory and may reveal a life-threatening problem that needs medical attention long
before surgery can even be contemplated. In most cases these lizards are in a state of severe
dehydration but fortunately uric acid levels are often low to moderately elevated as a result of the
anorexia. Fluid therapy using lactated ringers (Hartmanns) or 0.180/0 saline/4% glucose is
recommended. F ids are best delivered i.v. into the cephalic vein of larger lizards or i.o. into the
proximal ti
of most species. In patients where this is not feasible the intracoelomic route can be
used. Standard texts quote rehydration rates of 10-40 ml/kg/day for Lv. or i.o. fluid administration.
The author has had no problems with the higher rate of 40-50 mllkg/day. Indeed, for the first 1-2 hr
a shock fluid rate of 100 ml/kg/dayhas been used without adverse effects. The use of infusion
pumps (electrical or spring action) enables the small volumes of fluid required to be administered
at an accurate rate. The lizard must be hospitaliz and maintained at 30-35 °C (depending upon
species)" Antibiotics, allopurinol and other medications may be employed as indicated but fluid
therapy and a suitable environment remain most important.
A good quality dorsoventral radiograph is a ays indicated. In cases of post-ovulatory egg stasis
( ES) the eggs may occupy most of the coelomic cavity, often appear oval in shape and possess
a thin, sometimes barely perceptible, shell. In cases of pre-ovulatory ova stasis (POOS) the ova can
. also occupy most of the coelomic cavity and often appear as more rounded without any shell.
Injecting a small volume of air into the coelomic cavity can improve contrast and visualization of the
individual ova.
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1996 PROCEEDINGS ASSOCIATION OF REPTILIAN AND AMPHIBIAN VETERINARIANS
Pre-ovulatory ova stasis (POaS)
In cases where the ova enlarge but do not ovulate and remain within the ovary the term pre-ovulatory
ova stasis (POOS) is applicable. In such circumstances the presence of the greatly enlarged ovaries
severely reduces the coelomic space available to the gastrointestinal tract resulting in prolonged
anorexia. In most untreated cases affected females usually die from the secondary changes
associated with dehydration and anorexia. A diagnosis of poas can be made by ultrasonography,
laparoscopy or more commonly radiography. It is possible for the ova to spontaneously resolve over
a period of 2-8 wk. However, if affected animals are completely anorexic and becoming debilitated
then further deterioration and death can ensue before the problem resolves naturally. If
ical
therapy is contemplated then intensive nutrition fluid support win be required for many wee and
ova res
should be monitored using radiography or ultrasonography. In the author's experience
medical management is seldom successful in lizards prasen
e in the course of the disease and
does not prevent recurrence the lowing year. Greater success has been seen with short term
patient stabilization using 10 fluid therapy for 1-3 day followed by surgery (ovariosalpingectomy). A
case of follicular aspiration as a treatment for poas has been reported 4 •
Post-ovulatory egg stasis (POES)
In cases of post-ovulatory egg stasis (POES), the eggs (usually shelled) are located within the
oviduc but normal laying at term fails to occur because of the lack
a sui
e nesting site
(tern rature, humidity, nest materi ,seclusion), excessive disturbance by the owner, competition
for nesting sites (overcrowding), stress of transportation, metabolic disturbances (particularly
involving calcium), systemic or calized infections of the oviducts or cloaca and obstructions due
to abnormal eggs or cloacal prolapse. The space occupied by the eggs again compresses the
gastrointestinal tract and leads to secondary hypophagia or anorexia.
If there is no indication of infection, metabolic disease or obstruction as determined by radiography,
digital palpation and direct visualization of the cloaca and a limited hematological and biochemical
assessment, then conservative treatment should be sttempte
ovision afa suit Ie environment
and nesii site may well be II that is required to persuade t
to lay naturally. If o,viductal
inertia is suspected then medical treatment using oxytocin is indicated.
oan can be administered
at ados
IU/kg i.m. repeated a
min. In the
experience, oxytocin at 5 IU/kg given
by slow intravenous or intraosseous infusion over 4-8 hr has been most effective. Arginine vasotocin
at 0.01 1 JiQ/kg i.vs is considered more efficacious than oxytocin 1• Parenteral calcium therapy is
not necessary unless hypocalcemia is confirmeds
01
Complications including abnormal eggs, doacal prolapse, suspected infection
oviducts will prevent normal laying and in these cases surgery is indicated.
the cloaca or
Surgical technique
Once the patient's hydration status has been returned to normal (as determined by serial packed cell
volume, total protein and albumin) surgery can proceed. Premedication using anticholinergics,
phenothiazines and benzodiazepines have been advocated but their importance is questionable5 •
Preoperative antibiotics, for example 20-40 mg/kg ceftazidime (Fortum, 500 mg, Glaxo), 1M is
advisable. The rate of fluid administration can be increased to 5 mllkg/hour during anesthesia,
surgery and the immediate postoperative period5 •
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Anesthesia is induced with 10-14 mglkg propofol (Rapinovet, 10 mg/ml, Mallinckrodt Veterinary), Lv.
followed by intubation and maintenance on oxygen and 2-30/0 isoflurane. It is vital than the preferred
body temperature of the patient is maintained before, during and after surgery. The use of a low
wattage heat mat or water bed to maintain a core body temperature of 30 C is recommended. The
subject is connected to an ECG or pulse oximeter, and prepared for aseptic surgery. The use of
plastic adhesive drapes enables better monitoring and are to be preferred over cotton drapes.
0
A standard paramedian or mid-line coeliotomy is performed, avoiding the large, ventral, midline
venous sinus and, often voluminous, bladder',7,8. The incision may have to extend from the zoophyte
process to just cranial to the pelvis to provide sufficient exposure. The bladder must be identified to
prevent accidental incision, and emptied by cystocentesis if necessary.
In cases of P~~S, the enlarged ovaries will be immediately obvious, often resembling clusters of
yellow-orange grapes. Each ovary, supplied by 4-8 ovarian vessels that branch off the two dorsal
aortae, is lifted to expose these vessels which can be clamped using hemoclips, or ligated using
Vicryl (3/0-5/0)0 Once clamped the ovaries can be dissected free and removed. The oviducts are
usually small and appear norm . Theoretically it may be possible to leave the oviducts in place but
subsequent infection is always a possibility and therefore removal is recommended. The small blood
vessels can usually be sealed using radiosurgery, hemoclips or ligatures as necessary. The oviducts
should be double ligated using 3/0-5/0 Vicryl as far distally as possible, at their insertion to the
cloaca.
In cases
POES, it is the thin oviducts full of eggs that are immediately obvious. Multiple
incisions can be made to remove the eggs in an effort to maintain future breeding
capacity, however, surgery
is greatly extended. In most cases complete salpingectomy is
recommended.
large, numerous blood vessels that branch from the dorsal aortae to supply
oviduct must be I
Hemoclips greatly
su
time and more than vessel can often be
damp
a single medium dip. The oviducts must be ligated close to the
and removed
as descri d above. In these cases, the ovaries are often small lying on top of the dorsal aortae.
Their removal is considered by some to be unnecessary as it has been suggested that
folliculogenesis requires feedback from the shell glands of the oviducts. The author prefers complete
ovariosaipingectomy due to the possible danger of ectopic ova in the future. When removing inactive
ovaries the ovarian vessels are smaller and shorter and it is generally easier to clamp these vessels
with hemoclips than to ligate them. Special care is also required not to damage the closely
associated adrenal glands.
$~I
·
The coelomic membrane and mus
skin is sutured US~
3/
inverting
returned to a vivarium at
layers are closed in a routine manner using 3/0-5/0 Vicryl. The
0 nylon in an everting horizontal mattress pattern. This will prevent the
of reptilian skin and prevent dysecdysis in the future. The patient is
C to recover. Postoperative antibiotics are not routinely required
unless in
n was con
ad at surgery but parenteral fluid therapy remains essential for the next
24 hr. Discharge
icaUy occurs the next day with a return to normal feeding within a week. Skin
sutures are removed in 6-8 wk.
81 illOlIULAlill.w":BJII
0
Prevention
Prevention is to be preferred over treatment and therefore routine ovariosalpingeclomy can be
recommended for lizards for similar reasons as ovariohysterectomy is recommended for other
domestic pets.
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LITERATURE CITED
1. DeNardo, D. (1996). Reproductive Biology. In: Reptile Medicine and Surgery. First edition
(Ed. D. R.
der). W.B. Saunders, Philadelphia. Pages 212-224.
piile Reproduction. In: Biomedical and Surgical Aspects of Captive
2. Frye, F.L. ( 91).
Reptile Husbandry. Second edition. Krieger,
labar. Pages 345-392.
3. Zwart, P. (19 . Urogenital System. In: Manual of Reptiles. BSAVA, Cheltenham. Pages
120-127.
4. Orosz, S.E., Toal, R.L., Korenek, N.L. and Teubner, V.A. (1992). Follicle aspiration for the
treatment of pre-ovulatory egg binding in a green iguana. Journal of Small Exotic Animal Medicine
1(4): 161-165.
5. Bennett, R.A. (19
. Anaesthesia. In: Reptile edicine and Surgery. First edition (Ed. D.
R. Mader).
Saunders, Philad phis. Pages 241-247.
6.
Nardo,
(1996). Dystocias. In:
tile edicineand Surgery. First edition (Ed. D. R.
Mader).
sunders,
ladelphis. Page
0-374.
7. Barten, S.LD (1
). The medical care of iguanas and other common pet lizards. The
Veterinary
· of North America ... Small Animal Practice (Exotic P
icine I) 2
: 1213..1249.
, T.H. (11991).
mmon problems a
treatment of green iguanas (Iguana iguana).
Bulletin of the Association of Amphibian and Reptilian Veterinarians 1(1): 8...11.
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