Reproductive Disease in Reptiles

Veiled chameleon distended coelom Mede

Lecture outline

Lecture topics will include:

veiled chameleon
  • Normal reproductive strategies
    • Anatomy
      • Difference between reptile classes
      • Gender ID
    • Physiology
    • Oviparity vs viviparity
    • Incubation and hatching eggs
    • Sex determination
  • Pre-ovulatory or follicular stasis
  • Post-ovulatory dystocia
  • Cloacal prolapse

 

Abstract

Reptile reproduction can be a confusing topic due to the variety of normal reproductive strategies found throughout different reptile species. It is however important to understand normal reproductive processes in order to understand the approach to some of the commonly seen problems.

Broadly reptiles can be divided into those which reproduce by laying eggs (oviparity) and those that produce live young (viviaparity). Reproduction may often be a seasonal process and the presence of a male is not always required for eggs to be produced as long as the appropriate environmental stimuli are in place. Differentiating male from female reptiles is not always straightforward especially in juvenile animals. Owners will often be unaware or misinformed of the sex of their pet, particularly if purchased when young and therefore not anticipating certain reproductive problems.

Commonly seen reproductive problems include follicular stasis, post-ovulatory dystocia and cloacal prolapses which can all be seen in captive reptiles.

Follicular or pre-ovulatory stasis occurs when follicles are produced by the ovaries but ovulation does not ensue. Clinical signs include reduced appetite, lethargy and sometimes hindlimb weakness. However despite reduced appetite, weight is often not significantly reduced and sometimes increased due to the weight of the follicles. Blood work can be suggestive of reproductive activity, although imaging is required to confirm diagnosis. Ovariectomy is usually the treatment of choice.

Post-ovulatory dystocia may occur for many reasons including husbandry deficiencies and systemic disease. If not actively straining, the biggest challenge is determining whether the reptile is truly dystocic or simply at an advanced stage of gravidity. Imaging is recommended to confirm number of eggs or fetuses present and identify any factors which may be causing the dystocia. Both medical and surgical treatment options can be considered with medical options more successful in chelonian species.

Cloacal prolapses can occur for many reasons including excessive mating behavior, low calcium levels and dystocia, but also non-reproductive disease. Prolapses may be just cloacal or involve intestine, bladder, oviduct or hemipenes. Identification of both the type of prolapse and underlying cause are important in order to select the appropriate treatment option with the best possible outcome.

 

About the presenter

Joanna Hedley qualified from the Royal (Dick) School of Veterinary Studies in 2003 and spent time in mixed, small animal, exotic, and wildlife practice before undertaking a residency in Exotic Animal and Wildlife medicine back at R(D)SVS. Jo obtained her Royal College of Veterinary Surgeons Diploma in Zoological Medicine in 2012 and European College of Zoological Medicine specialist status in herpetology in 2014. She is currently Head of the Exotics Service at the Royal Veterinary College in London. [MORE]

 

Webinar recording

 

Post-test

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Expert Q+A

Dr. Hedley was able to answer most questions submitted during the live webinar question and answer feature, but the remaining questions were answered by email and are posted below:

Q:  Calcium glubionate is no longer available in our state, is there a good alternative

A:  My personal experience is using calcium gluconate or borogluconate at 100mg/kg. If injectable options aren’t available, then oral calcium supplements can be used instead and although obviously not as helpful in the critical patient, we have been able to track consistent increases in ionized calcium using these.

Q:  What substrate do you use when taking in a female?

A:  In hospital we generally use an easy to clean paper substrate over most of the enclosure floor, but then provide one or two nesting areas if trying to encourage egg laying, with whatever the animal is used to or prefers. Usually for us that is a soil mix although others prefer moist vermiculite.

Q:  Does time of induction of oviposition affect fertility?

A:  There doesn’t seem to be any firm evidence that inducing oviposition affects fertility, but if the animal is struggling to lay normally then I would question whether it has reproductive tract pathology and that may affect whether future attempts at reproduction are successful.

Q:  I am a new grad, and I am interested in seeing reptiles and other exotics in my general practice, but currently nobody in my practice sees them, and I am hesitant to start without much support. What advice do you have in terms of getting started seeing reptiles in practice? Thanks!

A:  This is a challenge, but often a familiar situation. I would advise anyone interested in building their reptile caseload to start with attending CPD sessions (as you are obviously already doing!) both online and in real life to learn more and to start building up a network of other vets you can ask for advice. Also joining the Association of Reptilian and Amphibian Veterinarians which can provide great links and resources as well as attending their regular conference where you can meet other reptile vets too and benefit from practical sessions too. Finally there are some great textbook and online resources available nowadays, including obviously the LafeberVet website which can help you approach many of the common reptile presentations.

Q: Can sugar solution or glucose be used to reduce swellings with prolapses, and how much would you use? Are there any complications of using this?

A:  Sugar solution or glucose can be used directly on the prolapse to reduce the swelling very effectively. In terms of complications, issues could be seen if the the sugar isn’t lavaged off well afterwards as potentially this could encourage bacterial overgrowth and subsequent infection, but it’s not a complication I’ve personally seen.

Q:  Are neoplasms common as a reproductive problem in reptiles? If so, what?

A:  Reproductive neoplasia can definitely occur in reptiles, although it does not appear as common as the conditions discussed in the webinar. Examples include ovarian teratomas, oviductal leiomyomas, and Sertoli cell tumors. I suspect these will be more commonly detected as we begin to see captive reptiles living to an older age.

Q:  Do you often see follicular stasis causing cloacal prolapse? (Should we always check a radiograph with a prolapse)?

A:  This wouldn’t be a common cause of cloacal prolapse, but this could potentially happen if the follicles are taking up large amounts of space and especially if the animal is weak and hypocalcemic. I always like to perform a full work up for reptiles with a prolapse whenever possible, but at minimum I think x-rays should be performed as a quick and easy screen for abnormalities such as foreign bodies, eggs or space occupying lesions.

 

Comment: I have just one comment about leopard geckos:
Dr. Hedley stated that at lower temperatures females are produced and at higher temperatures males are produced. This was also part of the CE questions. That statement does contradict some peer reviewed literature from the 90s (these are PubMed abstracts):

J Exp Zool. 1993 May 1;265(6):679-83. Temperature-dependent sex determination in the leopard gecko, Eublepharis macularius. Viets BE, Tousignant A, Ewert MA, Nelson CE, Crews D.

Physiol Behav. 1994 Jun;55(6):1067-72. Incubation temperature affects the behavior of adult leopard geckos (Eublepharis macularius). Flores D, Tousignant A, Crews D.

Dr. Hedley wrote: This is a good comment and I apologize for any confusion caused. There is conflicting information in the literature about this, so the leopard gecko is not the most appropriate example in this case. A better example of more males hatching at higher temperatures would be the tuatara:

Grayson, KL, Mitchell, NJ, Monks JM., Keall SN, Wilson JN, Nelson NJ (2014). Sex ratio bias and extinction risk in an isolated population of tuatara (Sphenodon punctatus). PLoS One, 9(4), e94214.

Note: Based on this feedback, the original post-test question was replaced.

 

RACE approval

This program 776-33856 is approved by the American Association of Veterinary State Boards (AAVSB) Registry of Continuing Education (R.A.C.E.) to offer a total of 1.00 CE credits to any one veterinarian and/or 1.00 veterinary technician CE credit. This RACE approval is for Category Two: Non-Scientific Clinical using the delivery method of Interactive-Distance/Non-Interactive Distance. This approval is valid in jurisdictions which recognize AAVSB RACE; however, participants are responsible for ascertaining each board’s CE requirements. RACE does not “accredit” or “endorse” or “certify” any program or person, nor does RACE approval validate the content of the program.