Ecdysis / dysecdysis
Synonym(s): Shedding / poor shedding
Introduction
- Definition:
- Ecdysis: the process of shedding the dead outer skin in reptiles.
- Dysecdysis: abnormal shedding of the dead outer skin in reptiles.
- Cause: dehydration, skin infection, skin wounds, burns, scars, ectoparasitism, poor or unbalanced diet, suboptimal husbandry, suboptimal environmental temperatures, stress, metabolic issues.
- Signs: snakes shedding skin in pieces, retained sheds in lizards/chelonia (especially around toes and tail in lizards). Terrapins not shedding their scutes properly.
- Diagnosis: physical examination.
- Treatment: improve husbandry and diet, rehydration, treat underlying disease/skin infection, ectoparasite treatment and control.
- Prognosis: fair to good.
Ecdysis and the pathogenesis of dysecdysis
- Reptile skin is unique, differing from mammals in thickness, elasticity and strength Chelonia anatomy and physiology Lizard anatomy and physiology Snake anatomy and physiology.
- Snake and lizard skin consists of a series of elevated scales continuous with each other at a hinge region.
- Each body scale has an outer surface, and an inner surface which overlaps the adjacent scale.
- Only the epidermal components of the scale participate in the shedding process.
- The shedding mechanism, ecdysis is a normal characteristic of most reptiles, is usually periodic and complete in snakes and some lizards but often only partial in other species.
- Ecdysis is dependent upon the health of the snake, the ambient temperature, humidity and other environmental factors.
- In all snakes, the whole epidermis is shed, including spectacles.
- The epidermal splitting occurs after the infiltration of lymph and enzymes between the old and the new skin.
- Younger animals shed the skin more frequently than older animals.
- Healthy adult pythons undergo ecdysis approximately every 2-3 months; in younger snakes it occurs more often.
- Dysecdysis occurs commonly when environmental conditions are not ideal, eg suboptimal temperature, humidity and enclosure hygiene, stress, etc.
- Hyperthyroidism may cause an increased frequency of ecdysis in some snakes (every 10-14 days).
- Other underlying disease can also manifest with dysecdysis.
Presenting signs
- Lizards: retained skin on limbs and digits; distal swelling of limbs due to constriction; mite infestation.
- Snakes: skin shedding in parts and not whole; mite infestation.
- Chelonians: scutes retained.
Acute presentation
- Distal swelling or edema of limbs, toes or tail due to constriction.
Cost considerations
- Minimal.
- Husbandry changes.
- Might need further medical work-up for underlying diseases.
Pathogenesis
Etiology
- Dehydration.
- Ectoparasites (Ophionyssus natricis).
Predisposing factors
General
- Poor husbandry Chelonia husbandry Lizard husbandry Snake husbandry.
- Poor nutrition Nutritional requirements.
- Chronic problems.
Specific
- Dehydration.
- Temperatures.
- Poor diet.
- Anorexia.
- Skin infection/wounds.
- Scars.
- Ectoparasites.
- Stress.
Pathophysiology
- Major differences in physiology and cutaneous biology between mammals and reptiles
- Epithelium is thin, consisting of one or two layers of cells covered by two zones of keratin.
- Dermal-epidermal junction is smooth.
- Dermis is thinner and less vascular than mammalian skin.
- Fewer glandular structures.
- Dermis is attached to the underlying musculature by a small amount of loose connective tissue.
- Range of stiffness or elasticity in snake skin is great compared with other vertebrate groups.
- Diversity in the structure and function of dermal collagen fibers.
- Epidermal growth and replacement of the old layer with the new is continuous in chelonians and crocodilians or discontinuous in lizards and snakes.
- Shedding cycle in lizards and snakes has a resting stage, followed by 5 stages of renewal.
- As a snake enters the renewal stages the skin becomes more dull and blueish in color due to the presence of lipid between the two layers:
- The scales are rougher to touch.
- The spectacle becomes milky in appearance.
- Ecdysis is controlled by the pituitary/thyroid axis.
Timecourse
- Ecdysis: frequency varies, depending upon on metabolic rate, environment, external factors.
Epidemiology
- Dysecdysis: multiple animals may be affected if dry environment, poor hygiene, lower temperatures, ectoparasites are mitigating factors.
Diagnosis
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Treatment
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Prevention
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Outcomes
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Further Reading
Publications
Refereed papers
- Recent references from PubMed and VetMedResource.
- Maderson P F A (1965) Histological changes in the epidermis of snakes during the sloughing cycle. J Zool 146 (1), 98-113 WileyOnline.
Other sources of information
- Jacobson E R (2007) Reptile Immunology. In: Infectious Diseases and Pathology of Reptiles. Ed: Jacobson E R. CRC Press, USA. pp 131-166.
- Cooper J E (2006) Dermatology. In: Reptile Medicine and Surgery. Ed: Mader D R. Elsevier, USA. pp 196-216.
- Fitzgerald K T & Vera R (2006) Dysecdysis. In: Reptile Medicine and Surgery. 2nd edn. Ed: Mader D. Saunders Elsevier, USA. pp 778-785.
- Jacobson E R (1991) Diseases of the Integumentary System of Reptiles. In: Dermatology for the Small Animal Practitioner. Eds: Ackerman L & Nesbitt G. Veterinary Learning Systems Company, USA.