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Cystotomy has been reported in a variety of amphibians including Phyllomedusa spp. (Wright and Whitaker 2001a; Archibald et al. 2015) that seem to be predisposed to ammonium urates uroliths due to their uricotelism (the production of uric acid). With the patient in dorsal recumbency, make a ventral paramedian incision using a #15 scalpel blade. Exteriorize the urinary bladder to avoid contamination of the coelom as bacteriuria is normal in amphibians (Johnson et al. 2015). Incise the bladder wall with a #15 blade. Close the bladder in a simple continuous pattern with fine poliglecaprone 25 suture after removing the calculi, and then suture the coelomic cavity with a simple continuous pattern with fine polydioxanone suture (Archibald et al. 2015).

Partial or complete cystectomy is an option in amphibians with bladder necrosis secondary to chronic bladder prolapse or with untreatable mucosal lesions because the ureters connect to the cloaca and not the urinary bladder (Archibald et al. 2015).

Surgical harvest of oocytes from laboratory amphibians is a commonly performed procedure, especially to design transgenic frogs (Green 2010). To collect ova, place the frog in dorsal recumbency and perform a paramedian ventral incision with particular care to not puncture the lungs, the urinary bladder, or the enlarged ovaries. The ovaries with mature follicles extend ventrally in the coelom and are easily visualized (Figure 6.9). Grasp the ovaries with forceps and exteriorize them onto the plastic drape, as the skin is not sterile. Excise the desired number of oocytes using scissors. No ligature is necessary to collect a small portion of the ovary (Gentz 2007). Close the coelomic incision in two layers. Place simple interrupted sutures in the muscle layer and simple interrupted, vertical, or horizontal mattress monofilament sutures in the skin (Green 2010). The procedure can be repeated every three to six months in a single female.

Ovariectomy is performed in adult females. Make a ventral paramedian incision. Use an eyelid retractor to facilitate visualization. Exteriorize the ovaries onto the plastic drape with cotton tip applicators. Use electrocautery, diode laser (Chai 2016), place hemostatic clips, or ligate the ovarian pedicles with polydioxanone suture (Wright and Whitaker 2001a). Transect the pedicle and retrieve the ovary. After repeating the procedure contralaterally, lavage the coelom and suture the coelomic muscles and skin in two layers. If the muscular layer is very thin, place a collagen pad in the coelom to improve the security of the suture, especially in laying females (Meier 1982). Ovariectomy may predispose amphibians to becoming overweight (Wright and Whitaker 2001a).

Figure 6.9 Location of the ovaries (white arrow) in a reproductively active Gray tree frog (Hyla versicolor).

Source: Photo courtesy: Zoological Medicine Service, Université de Montréal.

Castration is performed in a similar manner to ovariectomy. Make a paramedian ventral incision and locate the intracoelomic testicles cranial to the kidneys. Testicular vessels are shorter than ovarian vessels. Gently elevate the testis to place hemostatic clips or ligating sutures. Use small overlapping hemostatic clips in large specimens rather than choosing large hemostatic clips which are more prone to slip if not closed appropriately resulting in hemorrhage. Cauterize the bilateral ductus deferens with electrocautery and transect the testicle distal to the clips. Close the coelom in two layers of monofilament suture. Testicular biopsy is used in laboratories for reproductive studies (Gentz 2007). Make a small paramedian ventral incision and locate the intracoelomic testicles located cranial to the kidneys. Obtain biopsies with a biopsy forceps: close the forceps, wait and apply gentle pressure before pulling on the forceps to retrieve the biopsy. Apply counter‐forces to the testicle with a cotton‐tip applicator to avoid damage to the vasculature supplying the testicle. Close the coelomic incision in two layers with monofilament suture. Alternatively, endoscopy‐assisted testicular biopsy can be performed.