Surgery of Exotic Animals. Группа авторов

the stump (Wright and Whitaker 2001a). Place a tourniquet on the limb prior to amputation to reduce hemorrhage. Do not leave the tourniquet in place more than 15 minutes. Make a skin incision distal to the site of the planned bone transection to allow skin closure with limited tension. Prior to nerve transection, perform a local block with lidocaine and bupivacaine (Bainton and Strichartz 1994). Many newts and salamanders regenerate their limbs (Figure 6.6): the regenerated limb may contain a cartilaginous skeleton instead of bone and nerves regenerate with a resulting normal locomotion (Wright and Whitaker 2001a). Leave the stump open in these species as closure of the surgical site may prevent limb regeneration or result in abnormal regenerated tissue (Baitchman and Herman 2015).

Figure 6.4 Amputation of the tip of the tail of a California newt (Taricha torosa).

      Source: Photo courtesy: Companion Avian and Exotic Pet Medicine Service, University of California, Davis.

Figure 6.5 Surgical toe amputation in an African bullfrog (Pyxicephalus adspersus).

      Source: Photo courtesy: Companion Avian and Exotic Pet Medicine Service, University of California, Davis.

      As amphibians normally use their hind limbs during ecdysis, for nest building in females, and for amplexus in males, hind limb amputation may lead to dysecdysis and reproductive failures (Wright and Whitaker 2001a). Consequently, it is questioned whether amphibians should be released following permanent hind limb amputation.

Ophthalmic Surgery

      Given the moist environment for aquatic amphibians, corneal ulcers can be difficult to treat as ophthalmic topical aqueous solutions and ointments are quickly diluted. Deep corneal ulcers may be treated with a tarsorrhaphy or with butyl cyanoacrylate tissue adhesive (Williams and Whitaker 1994). Tarsorrhaphy is performed in a similar manner as domestic animals.

      Enucleation may be performed as a salvage procedure (Wright and Whitaker 2001a; Imai et al. 2009). Indications for enucleation are similar to those of other vertebrates and include nontreatable painful intraocular lesions and retro‐orbital neoplasms or abscesses (Williams and Whitaker 1994). Of note, amphibians have higher regenerative abilities than mammals and many anurans and newt are able to regenerate their retina while adult newts and African clawed frog tadpoles are able to regenerate their lenses (Filoni 2009). As a result, in patients with cataracts, removal of the lens allows the growth of a new transparent lens and retinal lesions that progress to permanent blindness in mammals may heal in amphibians. Temporary tarsorrhaphy may be performed to protect the cornea pending vision recovery.

Figure 6.6 An albino axolotl (Ambystoma mexicanum) presented with a traumatic amputation of the left forelimb (white arrow) and multifocal bite wound on the tail and left hind limb (black arrow). The left forelimb traumatic wound is left open to allow limb regeneration.

      Source: Photo courtesy: Aquarium du Québec.

In species that retract their globe during food swallowing, the globe is very mobile and a gauze should be placed in the mouth prior to ocular surgery (Chai 2016). After infusion of local anesthetic into the conjunctival tissue, incise the conjunctiva and dissect the extraocular muscles from the globe, which frees the globe from its attachments. Take care to not damage the tissue between the orbit and the oral cavity (Wright and Whitaker 2001a) and to not damage the facial vein (Forzan et al. 2012). Transect the optic nerve and vessels and control hemorrhage with pressure using a cotton‐tipped applicator or by packing the orbit with a collagen sponge (OraPlug, Salvin, Charlotte, NC) or an absorbable gelatin hemostatic sponge. If using hemostats to clamp the retro‐orbital vessels, avoid putting traction on the optic chiasm that would cause blindness in the contralateral eye. Tarsorrhaphy with nylon suture material is recommended in species with eyelids to facilitate hemostasis (Wright and Whitaker 2001a) (Figure 6.7). Second intention healing is also an option (Chai 2016).

Lens excision has been described in a milk frog (Tachycephalus resinifictrix) (Chai 2016). Make a two‐step circumferential incision over 180° at the limbus with a keratome with the first incision perpendicular to the globe and then a second deeper incision with a more pronounced angulation to prevent the cornea from collapsing. Inject viscoelastic medium in the anterior chamber. Retrieve the lens with a Snellen loop. Irrigate with saline. Suture the cornea in one layer with 9‐0 nylon, in a simple interrupted pattern.

Figure 6.7 Enucleation of the right eye in an Oriental fire‐bellied toad (Bombina orientalis).

      Source: Sepaq | Aquarium du Québec..

Coelomic Surgery

For a ventral coelomic cavity approach, position the patient in dorsal recumbency (Wright and Whitaker 2001a). A paramedian incision is recommended to avoid the ventral abdominal vein (Figure 6.8) (Wright and Whitaker 2001a). Incise the skin and coelomic muscles with a scalpel blade or iris scissors. Have an assistant, gently retract the coelomic wall or use a self‐retaining retractor such as Heiss, Lone Star, or Gelpi retractors or a Barraquer eyelid speculum. After celiotomy, the coelom should be sutured with absorbable monofilament suture material (Tuttle et al. 2006) in two layers, one for the muscle and one for the skin (Wright and Whitaker 2001a; Gentz 2007; Green 2010). In small amphibians, it is possible to suture both the muscle and skin in a single layer without complication (Archibald et al. 2015). When working with aquatic amphibians, such as newts, neotenic species, and tadpoles, positive buoyancy after anesthetic recovery is an important consideration, so gas should be removed from the coelomic cavity at the end of the procedure. The weight of hemostatic clips should be considered when working with small aquatic animals due to postoperative negative buoyancy issues.

Figure 6.8 Exploratory celiotomy in an Argentine horned frog (Ceratophrys ornata). Intra‐operative images.

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

      A ventral coelomic hernia has been successfully repaired in a female tomato frog (Meier 1982). Distended intestines were found to prolapse subcutaneously through a right lateral coelomic hernia. To repair a coelomic hernia, make a cutaneous incision medial to the hernia and replace the prolapsed organs into the coelom. If the coelomic musculature is thin and friable, place an absorbable gelatin sponge in the coelomic