Gross and Histological Evaluation of Five Suture Materials in the Skin and Subcutaneous Tissue of the California Sea Hare (Aplysia californica)
Invertebrate animals are ever increasing in their importance to both the public and private aquarium trade, and play a vital role in biomedical research. The California sea hare (Aplysia californica) is one of the most important models for neurophysiology research. Surgical techniques used in A. californica (subsequently referred to simply as aplysia) research experiments include probe placement within various nerves and ganglia.4,5 More recently surgical treatment has been shown to be valuable in addressing specific health problems in other aquatic invertebrate animals.1 The current study evaluated the gross and histological reaction of aplysia to five suture materials commonly used in veterinary medicine.
This study was conducted in conjunction with a teaching laboratory at the North Carolina Sate University, College of Veterinary Medicine (NCSU-CVM). Thirteen aplysia were immobilized with magnesium chloride, and five different suture types were placed in a single simple interrupted pattern at one of six predetermined sites. The five suture materials evaluated were polydioxanone (PDSTM II), black braided silk, polyglactin 910 (VicrylTM), monofilament nylon (MonosofTM), and monofilament poliglecaprone (MonofylTM). Six animals were then biopsied at 6 days, and the remainder at 12 days, after suture placement. Full histopathologic review was performed on all tissue samples. Samples were graded (1-4) on the amount of edema, inflammation, and granuloma formation present, and an overall histology score (1-6) was given to each sample.
A Wilcoxon rank sum test showed that there were no significant differences in histology scores between 6 days and 12 days after suture placement, so the data were grouped for the remainder of the analyses. A Friedman 2-way analysis of variance was applied, and where differences in suture reaction were found, the Wilcoxon matched-pairs signed-rank test was used to determine which pairs differed. The control samples had a median score of "1" for all categories. All suture materials were found to have significantly more tissue reaction than the control, but none of the suture materials were significantly different from the other suture materials. Silk, although shown to be very reactive in other animals,2,3,6,7,8 was the only suture type that did not have a significantly higher granuloma score when compared with the control.
None of the suture materials evaluated appears to be clearly superior to the others for use in aplysia, and perhaps other aquatic invertebrate animals. It was shown that silk is no worse, and potentially slightly better, than the other suture materials.
We would like to thank all of the students that participated in the 2008 NCSU-CVM Invertebrate Medicine Selective for their help with conducting the study, and especially Sam Young, Jenessa Gjeltema, and Margaret Maple for their help caring for the aplysia.
1. Harms C.A., G.A. Lewbart., R. McAlarney, L.S. Christian, K. Geissler, and C. Lemons. 2006. Surgical excision of mycotic (Cladosporium sp.) granulomas from the mantle of a cuttlefish (Sepia officinalis). J Zoo Wild Med 37: 524-530.
2. Hurty C.A., D.C. Brazik, J.M. Law, K. Sakamoto, and G.A. Lewbart. 2002. Evaluation of the tissue reactions in the skin and body wall of koi (Cyprinus carpio) to five suture materials. Vet Rec 151: 324-328.
3. Knowles RP. 1976. Critique of suture materials in small animal surgery. J Am Anim Hosp Assoc 12: 670-672.
4. Lum C.S., Y. Zhurov, E.C. Cropper, K.R. Weiss, and V. Brezina. 2005. Variability of swallowing performance in intact, freely feeding Aplysia. J Neurophysiol 94: 2427-2446.
5. Morton D.W. and H.J. Chiel. 1993. In vivo buccal nerve activity that distinguishes ingestion from rejection can be used to predict behavioral transitions in Aplysia. J Comp Physiol A 172: 17-32.
6. Tuttle A.D., J.M. Law, C.A. Harms, G.A. Lewbart, and S.B. Harvey. 2002. Evaluation of the gross and histological reactions to five commonly used suture materials in the skin of the African clawed frog (Xenopus laevis). J Am Assoc Lab Animal Sci 45: 22-26.
7. Wagner G.N., E.D. Stevens, and P. Byrne. 2000. Effects of suture type and pattern on surgical wound healing in rainbow trout. Trans Am Fish Soc 129:1196-1205.
8. Wood K.M., J.E. Collins, R. Walshaw. 1984. Tissue reaction to non-absorbable suture materials in the canine linea alba: a histological evaluation. J Am Anim Hosp Assoc 20: 39-44.