2021 (https://www.nobelprize.org/prizes/medicine/2000/summary/ accessed Mon. 2 Aug 2021). These factors and others make them important animals for veterinary consideration.
There is very little in the literature on gastropod surgery. Much of what is published deals with the amputation of structures like eyes and tentacles, and the surgical compromise of neural tissue to study regeneration (Moffett 2000; Tartakovskaya et al. 2003; Matsuo et al. 2010a,b). These procedures generally do not require wound closure or postoperative therapy. Anderson et al. (2010) determined that silk, among the five suture materials (braided silk, monofilament nylon, monofilament polylecaprone, polydioxanone, and polyglactin 910) tested in the skin of Aplysia californica, resulted in the least amount of granuloma formation. The amount of tissue reaction did not differ among the various sutures.
Figure 4.4 This image illustrates the major external anatomical features of a terrestrial shelled gastropod.
With regards to hard tissue surgery, there is a case report of shell repair in an apple snail, Pomacea bridgesii (Lewbart and Christian 2003). Apple snails are common in the pet trade and a number of species are maintained in aquariums globally. The shell of a typical gastropod contains the apex, spire (made up of whorls), and the body whorl, which terminates at the aperture (Figure 4.4). The head and foot of the snail protrude from the aperture. The oldest whorls are those closest to the apex of the shell. The gastropod shell is composed of four layers. The outer periostracum is composed of conchin, a horny protein, and the internal layers are composed of calcium carbonate and organic material (Ruppert and Barnes 1994). A mature female apple snail crawled out of its aquarium, fell to the floor, and fractured its shell. A depression fracture and a full‐thickness “U‐shaped” crack were noted on the body whorl (Figure 4.5).
The fractured shell and underlying tissues were flushed with sterile saline and an abrasive Dremel drill bit was used to roughen the surfaces on each side of the fracture. Epoxy (Epoxy Putty®, Oatey, Cleveland, OH) was used to construct a bridge that was attached with digital pressure (Figure 4.6). A section of transparent bandage (Tegaderm®, 3‐M) was secured to the shell over the area of the depression fracture. Three months later the shell was stable, but the defects remained. Since mollusks lay down shell at the free edges of the mantle, they cannot regenerate or remodel shell in other areas. The stability of the shell was most likely due to soft tissue healing beneath the fracture sites.
Figure 4.5 This apple snail (Ampullariidae) suffered a fractured shell after falling from its aquarium onto a firm substrate.
Figure 4.6 The same snail in Figure 4.5 after the application of an epoxy bridge and transparent bandage.
Cephalopod Mollusks
There are about 800 species of cephalopods; a group that includes the octopuses, squids, cuttlefish, and chambered nautiluses. This is an important group in that they serve as a food source for humans and other animals, are popular display animals, and are frequently employed in a variety of research applications. Their acute vision, dexterity, and intelligence make them fascinating animals to observe and study. In Great Britain an Institutional Animal Care and Use Committee (IACUC) application is required to perform research on cephalopods, largely due to their sentience (Mather and Anderson 2007). Unfortunately, most species are short‐lived in the wild and captivity. Common problems in captivity include trauma, anorexia, microbial infections, and water quality challenges (Hanlon and Forsythe 1990; Sherrill et al. 2000; Scimeca 2012).
There is not a lot of published information on clinical cephalopod surgery. Harms et al. (2006) describe surgical excision of fungal granulomas from a cuttlefish (Sepia officinalis) mantle. They did not use any surgical scrub for fear of damaging the sensitive skin or inducing toxic effects on the circulating anesthesia water. A 5 mm diameter wound was closed with 4‐0 polyglyconate on a taper needle using a simple continuous pattern. A larger (3 x 4 cm) wound was closed using the same suture and needle with an interrupted cruciate pattern.
A fairly large body of literature exists regarding research surgical procedures in cephalopods, particularly octopuses, but most of the surgeries are short and apply to amputation and destruction of organs and tissues in order to study behavior, regeneration, and behavioral and physiologic responses (Wells and Wells 1975; Wells 1980; Andrews et al. 1983; Sumbre et al. 2001; Fossati et al. 2013).
Annelids
The annelids are a large and diverse group of segmented vermiform animals that are divided into three main classes: the Polychaetes, Oligochaetes, and Hirudineans. All are characterized by regular segmentation of the trunk. It is believed this segmentation evolved as a means of burrowing via peristaltic contractions (Ruppert and Barnes 1994). Annelids have a coelomic cavity that is divided into segments by septa. The circulatory, excretory, and nervous systems are also segmented. A cuticle covers the animal and segmented setae occur in nearly all members of the phylum. The mouth is located cranially and the anus caudally with a straight gut between the two openings (Ruppert and Barnes 1994). Certain species such as tropical marine polychaetes like feather duster and Christmas tree worms are important and valuable display animals.
Some polychaetes and oligochaetes have the capacity to regenerate portions of their bodies (Ruppert and Barnes 1994). Park et al. (2013) reports on healing and blastema formation after tail amputation in earthworms. Like coelenterates and cephalopods, this has led to experimental amputations and bisections requiring nothing more than a scalpel or other sharp instrument (Bely and Wray 2001; Zattara and Bely 2011). In nearly every case, the details of the procedure are minimal (e.g. a scalpel was used or amputated with a scalpel). Much of the early research on tissue grafting and rejection was performed on earthworms (Cooper 1968, 1969a,b; Bailey et al. 1971; Cooper and Roch 1986). More recently, earthworms have been used as models for microsurgery training (Figure 4.7) since they resemble mammalian vessels and are superior to synthetic materials (Ramdhian et al. 2011; Leclère et al. 2012, 2013).
Figure 4.7 This series of images shows how earthworms can be a model for vascular surgery training (anastomosis). (a) Clamping the earthworm (Lumbricus sp.), (b) opening the body lumen, (c) two initial sutures, and (d) completed anastomosis.
Source: LeClere et al. 2013.
