Snakes Flashcards
Taxonomy - Families for boa constrictors; pythons; king snakes
Boidae, pythonidae, colubridae
Taxonomy - Families for vipers; cobras and coral snakes
Viperidae, elapidae
Gland that regulates frequency of ecdysis
Thyroid
Bone that connects mandible to skull and allows for opening of jaws !80 deg
quadrate bone
Groups of snakes that possess two lungs
Boas, pythons - R is primary and L is reduced
Group with heart located more cranially (ecological niche)
arboreal
Ophidian heart chambers
sinus venosus, R atrium, ventricle, L atrium; coronary sulcus between atria and ventricle
Taxonomy - Families with external spurs for courtship
Boidae, pythonidae
Describe differences in anatomy betwen cranial, transitional, and caudal aspects of the snake lung
Cranial (thick, vascular, respiratory), transitional (thin-walled, semi-vascular, variably respiratory), caudal (membranous, avascular, saccular, nonrespiratory). Lesions typically in cranial lung.
List important considerations for housing venomous snakes
Enclosure must have a locking mechanism, snake must be visible form outside, appropriate signs and emergency bite protocols
Minimum quarantine period recommended for snakes
90 days
Analgesic of choice in snakes
Butorphanol (high dose 20 mg/kg) NOT morphine like other reptiles
Vessel of concern during approach for coeliotomy in snakes
Abdominal vein, ventral midline
Inclusion body disease etiologic agent
Arenavirus (enveloped RNA virus)
Inclusion body disease CS in pythons vs boas
Regurgitation (boas), neuro signs (opisthotonus, torticollis, lack of righting), pneumonia; ball pythons die within weeks, boas die after mos to years
Inclusion body disease gross and histologic lesions
Splenic and pancreatic atrophy; intracytoplasmic eosinophilic to amphophilic inclusions in multiple tissues (boas) or CNS (pythons)
Ferlavirus - What tyep of virus?
Paramyxovirus (ssRNA)
What paramyxovirus is NOT within genus Ferlavirus
Sunshine Virus
Ferlavirus clinical presentation, gross and histo lesions
Variable - No CS to severe resp dz with or without tracheal exudate, neuro signs; caseous-necrotic material within lungs, hemorrhages, and dermatitis; histo - Proliferative interstitial pneumonia with occasional intracytoplasmic eosinophilic inclusions
Bacteria causing granulomatous dz in puff adders and emerald tree boas
Chlamydophila pneumonia
Causative agent of snake fungal dz
Ophidiomyces ophiodiicola
Drug of choice for SFD in snakes
Voriconazole (F8); combo therapy with terbinafine likely synergistic
Causative agent of necrotizing hepatitis and enterocolitis, hemorrhagic, parasite
Entamoeba invadens
Snake mite scientific name
Ophionyssus natricis
What are the three major clades of snakes?
What unique anatomy defines them?
- Scolecopidia – Fossorial, blind snakes.
- Vestigial eyes (rods only), blunt heads, short tails.
- Multi-lobed liver, mandibular raking mechanism.
- Oviparous, retain pelvic remnants.
- Alethinophidia – Early blind snakes.
- Most have well developed, bilateral ovaries, retain both pelvic vestiges and hindlimb remnents and left lung.
- Caenophidia – Advanced snakes.
- No hindlimb vestiges or left lung.
- Many possess a well-developed tracheal lung.
Describe the anatomy of the snake by body length thirds. What organs are present in each third?
- Proximal 1/3 – Esophagus, trachea, PT glands, thymus, thyroid, heart.
- Second 1/3 – Lung(s), continuation of esophagus, liver, stomach, spleen, pancreas, GB, proximal SI, air sac.
- Caudal 1/3 – Caudal small bowel, gonads, adrenal glands, kidneys, cecum, colon, cloaca.
What groups of snakes have facial pit organs?
How do they function?
- Vipers and many boas and pythons have facial pit organs.
- True eyes, function via infrared and electromechanical radiation.
- Trigeminal innervations differ by spp but innervations to the optic tectum of the brain allow for formation of images from sensory information.
Describe snake skin structure.
Do the scales have osteoderms?
Are there any specific glands? What are they used for?
Describe the sheddding process - what is it called?
Do juvenile snakes (generalization) have any differences in their coloring?
What gives snakes their iridescence?
What color and pattern mutation morphs exist (name a few) and are there any associated problems?
Integument
- No dermal osteoderms
- Epidermal scales protect from abrasion and dehydration - enlarged head shields, small dorsal/lateral scales, wide ventral protective scales
- Paired cloacal scent glands within base of tail in females and dorsal to hemipenes in males - defense and social signals; otherwise almost no skin glands
- Shedding - ecdysis
- Hormonal input from thyroid
- Proliferation of epithelial cells from stratum germinativum forms new epithelial generation between stratum germinativum and the older outer epidermal layer
- Younger epidermal layer keratinizes to resemble outer layer
- Anaerobic glycolysis assists in separating the outer layer and acid phosphatase helps breaks down cementing material
- Dull blue look as thin fluid forms between two layers - go blue for several days until fluid is resorbed and clears up
- Should shed entire skin in one event with the spectacles
- During shed cycle, many will refuse food and seek shelter in moist/humid site
- Should resume eating immediately after ecdysis
- Dysecdysis - r/o incorrect humidity, lack of proper substrate, improper handling, malnutrition, dermatopathy (trauma, ectoparasites)
- Pigment cells within skin and microscopic surface structures for iridescence
- Juveniles may have brightly colored tails to use as lures to attract prey
- Captive propagation of color and pattern mutation morphs (albinos, leucistics, hypomelanistic, patternless, scaless) - problems with inbreeding
Describe the cardiovascular system of snakes.
Does heart placement vary by ecological niche?
Why is the heart mobile?
Describe the great vessels.
What portal systems exist? How does this affect drug administration?
Where is the ventral coelomic vein - why does it matter?
Where is venipuncture performed?
Cardiovascular
- Position varies by species and ecological niche - arboreal snakes have more cranial hearts and aquatic snakes have more centrally located hearts
- Heart somewhat mobile - possibly to help facilitate large prey passing through
- Sinus venosus, right atrium, ventricle, left atrium
- Communication between ventricles allows for shunting (R-L, L-R)
- Paired aorta; left exits left side of ventricle and right aorta exits right side of ventricle -> fuse caudal to heart to form abdominal aorta; left arch is larger than the right; pulmonary artery also exits ventricle
- Paired carotid aa and jugular vv anterior to heart near trachea; jugulars can be accessed with cut down
- Can control arterial pressure reflexively - control reduced when snake’s body temp is lower or higher than preferred
- Oxygen dissociation curves may be influenced by temperature (not shown to be true in ball pythons)
- Renal and hepatic portal circulations - recommended to administer renal eliminated drugs in front half to avoid nephrotoxicity and first pass effects (however studies indicate that clearance of drugs via renal-portal system may rely more on how kidneys clear a drug with tubular excretion affected more than glomerular filtration)
- Ventral coelomic vein through coelom - Avoid in surgery by making approach at edge of rib cage between second and third dorsal (lateral) scale rows
- Blood collections - ventral coccygeal vein and cardiocentesis most common
- Jugular vein not common for venipuncture - ⅓ to ½ the distance between the base of the heart and base of the skull - collect blindly along medial rib margins or cannulated
- Dorsal palatine vein - difficult without sedation; hematoma is problematic
- Hematocrit 20-30%
- Black rat snake blood volume is about 6% of body weight
Describe the lymphoid tissue of snakes?
Lymphoid tissue
- Gastrointestinal tract (GALT)
- Esophageal tonsils - boas, pythons, a few colubrids
- May have significance in viral infections
Describe the respiratory anatomy of snakes?
What is important about tracheal anatomy?
How many lungs? Which is present?
Describe the internal structure of the lung.
How does inspiration occur without a diaphragm?
What is unique about the glottis?
How do bull, dopher, and pine snakes generate their distinctive defensive hissing?
Respiratory
- Trachea has incomplete cartilaginous rings - ventral portion rigid; vascular lung can extend into trachea (tracheal lung)
- Left lung is usually reduced or absent
- Boas and pythons - left lung is moderately large
- Right lung - near the heart -> cranial to the right kidney
- Cranial portion vascularized to function in gas exchange (vascular lung); caudal portion air sac (saccular lung)
- Lungs - trabeculae with faveolar spaces
- Cranial: thick, vascular, respiratory - typically where lesions are seen
- Transitional: thin walled, semi vascular, variably respiratory
- Caudal: membranous, avascular, saccular, nonrespiratory
- Lungs - trabeculae with faveolar spaces
- Vascular lung - honeycombed units of gas exchange - faveoli
- Inspiration occurs by muscular expansion of the rib cage creating negative pressure
- Glottis is mobile and can extend cranial and/or lateral as necessary to facilitate breathing while ingesting large prey
- Epiglottal cartilage enlarged/modified for defensive hissing - bull, gopher, pine snakes
Describe ophidian digestive anatomy.
What are the four fang types?
What are the primary venom toxins?
How is food moved within the GI trach?
Describe liver anatomy.
Describe the anatomy of the pancreas, spleen, and gall bladder.
Describe the musculature of the esophagus, stomach, and intestines.
How long are the intestines compared to other reptiles?
Digestive
- Prey moistened/lubricated with mucus from palatine, lingual, sublingual, and labial mucus secreting glands in oral cavity
- Venom glands are modified labial glands in upper jaw below orbit
- Teeth
- 6 rows - one row on each mandibular bone and two on each maxillary region
- not differentiated except for those with specialized fangs
- replaced throughout life
- generally modified pleurodont teeth with a socket attached to the side of the bone
- vipers/pit vipers - fangs fold caudodorsally (solenoglyphous)
- Elaphids (proteroglyphous) and fanged colubrids - fangs do not fold
- Aglyphous - homodont maxillary teeth (more primative snakes)
- Opisthoglyphous - rear fanged - enlarged teeth in posterior maxilla
- Venom toxins: neurotoxins (neuromuscular junctions), hemorrhagins (destroy blood vessels), myotoxins (skeletal muscle); venom contains a variety of enzymes; including digestive
- Tongue forked tip and lives within a sheath beneath the epiglottis - olfaction (vomernasal organs on roof of mouth); snakes that lose their tongues may stop feeding
- Esophagus distensible, largely amuscular
- Use axial musculature and skeleton to transport food
- Lack cardiac (gastroesophageal) sphincter
- Stomach muscular, distensible for digestion
- Small intestine linear
- Liver - left and right lobes, dorsal portal vein, ventral hepatic vein
- Pancreas in triad with gallbladder and spleen distal to posterior tip of elongated liver; some sp have splenopancreas
- colon empties into cloaca (cr-cd - coprodeum, urodeum, proctadeum); urates and feces temporarily stored in colon and cloaca; role in water conservation
- Small cecum present in proximal colon - boas and pythons
- Fat bodies within coelom - each side of cavity, small group cranial to heart
- Shortest intestines of all reptiles.
Describe ophidian urinary anatomy.
Where are the kidneys located? How are they shaped?
Where do the ureters empty?
Describe the function of distal convoluted renal tubules in male snakes.
What is the primary nitrogenous waste?
Can snakes concentrate urine?
Urinary
- Paired lobulated elongated kidneys are caudal dorsally located last 25% of snout to vent length
- Kidneys have craniocaudal orientation; right cranial to left
- Ureters empty into urodeum - no urinary bladder
- Males - distal convoluted renal tubules hypertrophy during repro season and contribute to seminal fluid production -> kidneys have increased size and are paler
- Uric acid is the primary nitrogenous waste -> produce white to yellow urates
- Unable to excrete urine at a higher concentration than plasma
Describe ophidian reproductive anatomy.
Where are the gonads located?
Where do the oviducts open?
Where does the vas deferens empty?
What unique reproductive behaviors exst?
How is snake sex determined?
Reproductive
- Males - paired hemipenes invaginated in pouches in ventral tail base; during copulation a hemipenis evaginates into cloaca of female; can determine sex with lubricated probe
- Gonads are cranial to the kidneys; right more cranial
- Females - Ovaries near the pancreas; each oviduct has a separate opening into the urodeum
- Some fossorial species have one ovary and oviduct
- Fusiform testes between pancreatic triad and kidneys - enlarge and regress with season
- Sperm carried in Wolffian ducts (vas deferens) into urodum and to the base of the hemipenes, travels up the sulcus spermaticus into females cloaca
- Diverse reproductive behaviors
- King cobras build nests for incubation
- Egg brooding - pythons, some colubrids, some vipers
- Some Crotalids exhibit parental care and remain with newborn until after shed
- Snakes (species studied) have genetic sex determination
- Females heterogametic: ZW, males homogametic ZZ in advanced snakes
- Primitive snakes (boids, pythons) - males are XY and females XX
- Sexual dimorphism is rare, females generally get to larger sizes
- Most snakes reproduce sexually; some are parthenogenetic (blind snake, file snake); rare parthenogenesis reported in some other species
Describe the unique musculoskeletal system of snakes.
How do their jaws function?
What are the four locomotion strategies?
Do snakes have intervetebral discs?
Musculoskeletal
- Quadrate bones articulate with lower jaw and palatomaxillary arch to facilitate large prey ingestion
- No mandibular symphysis; ribs not joined ventrally, body can expand
- Pelvic vestiges and external spurs (used in courtship in boas and pythons)
- Locomotion is relatively low energy
- Lateral undulation - bend vertebral column laterally
- Rectilinear locomotion - caterpillar crawling
- Concertina locomotion - arboreal and fossorial snakes; energy expensive
- Sidewinding - sand or mud; series of separate parallel straight lines
- Caudal autonomy rare; no regeneration
- No intervertebral discus
Describe the nervous and sensory anatomy of snakes.
How do snakes hear?
How do snakes accomodate their vision?
Where do lacrimal secretions go?
How do pit organs work?
What is the jacobson organ?
Nervous/Sensory
- Unable to identify CN XI in snakes
- No external auditory opening, tympanic membrane or middle ear - however shown to be electrophysiologically sensitive to airborne low frequency sound of 150-600 Hz
- Eyes lack ciliary bodies - iris muscle movements move lens toward or away from retina
- Lacrimal secretions flow through subspectacular space between cornea and spectacle and drain into oral cavity at the distal aspect of medial maxillae
- Shape of pupil varies
- Specialized infrared receptors - heat pits of pit vipers developed independently of labial pits in boas and pythons
- Pit vipers - one organ on each side of head ventral to a line drawn between nostril and orbit; heat pits have a thin membrane stretched over an air filled cavity; heat info, direction and distance
- Boas/pythons - labial or rostral scales or both, but varies with species
- Innervation trigeminal nerve
- Keepers feeding thawed prey may get bit if by hand - smell prey but sense heat of hand
- Jacobson’s organs (vomeronasal) in roof of mouth - olfactory function, spherical, separate from the nose, innervated by olfactory nerve; lacrimal duct enters the duct of the vomeronasal organ; odors relayed to it by the forks in tongue
- CNS diseases - Inclusion Body Disease (arenavirus) of boas and pythons (ataxia, opisthotonos)
Describe the endocrine anatomy of snakes.
Where do the thyroid glands live? What do they control?
Does teh thymus involute?
Where are the parathyroids located?
Endocrine
- Single or paired thyroid glands just cranial to the heart - controls growth and shed cycle
- Thymus does not involute in adults, but difficult to find in adipose tissue cranial to the thyroid
- Paired parathyroid glands often embedded in the thymus - calcium metabolism
- Adrenal glands within the gonadal mesentery
- Pituitary gland -appears to function similar to mammals
- Pineal gland secretes melatonin
- Clinical significance of endocrine function/dysfunction poorly understood in snakes
Describe the normal behavior of snakes.
How do they regulate body temperature?
List three reasons why a snake may be warmth seeking.
What species display facultative endothermy?
How should temperature control be provided in human care?
Describe feeding behavior - how should this be handled in managed care?
Describe snake to snake behavior.
Behavior
- Ectotherms - behaviorally regulate temperatures
- Warmth seeking - ill, gravid, digesting prey
- Facultative endothermy - brooding female pythons species able to maintain temps several degrees warmer than ambient temp
- Thermal gradient recommended in human care
- Brumation - winter dormancy
Behavior
- If cage is only opened for feeding, will likely exhibit a feeding response when cage is opened
- Can train snake that prey item will be presented by tapping on enclosure with metal forceps
- Feeding large snakes outside the cage may be recommended for safety
- Courtship related interactions can be dramatic - pheromones, visual cues, tactile cues
- Behavior can be completely different during mating season - aggressive; traumatic injuries can occur
- Housing snakes singly usually referred - aggression, cannibalism (feed separately)
- Wash hands prior to interacting with a snake, especially after handling prey or predator species
- Having a king snake or other snake-eating snake nearby can affect behavior, likely due to pheromones
Describe the appropriate housing for snakes.
What lighting requirements do they have?
How does humitidy play a role?
Describe appropriate housing for venemous snakes.
Housing
- Snakes are escape artists - escape-proof cage; need latch or lock
- Plastic shoe boxes, sweater boxes, modified aquaria, home made, commercially manufactured from fiberglass or ABS plastic - easy to clean and disinfect
- Lighting requirements less understood compared to other reptiles
- Attention to photoperiod - good health, successful reproduction
- UVB not documented as necessary, but can allow for basking behavior/increased activity in diurnal snakes
- Freshwater should always be available - water bowls cleaned and disinfected at least once weekly
- Winter - forced air heat/drying effect -> dysecdysis, respiratory disease
- Too much humidity - harmful to desert species
- Most snakes due well between 50 and 70% humidity with adequate ventilation
- Plants, rocks, tree branches recommended as enrichment
- Substrate - newspaper or paper for hospitalized patients unless fossorial or aquatic
- Hide box/shelter area recommended
- Large enough to allow for activity
- Cage styles
- Basic - one substrate, water bowl, hide box, plant/tree branch
- Wet to dry - one or two substrate, moist area and dry area
- Tree-layer -bottom is gravel (can be moistened), middle sand, top is mulch
- Desert - thick sand substrate, small water bowl, good ventilation
- Swamp tea - rare; dilute solution of tea for water environment
- Natural setups and outdoor enclosures - outdoor must be escape, vermin and vandal proof
- Venomous snakes should be housed in enclosures equipped with a locking mechanism and the snake must be visible from the outside. Appropriate signs and emergency bite protocol.
Describe the heating and lighting requirements of snakes.
Thermoregulation
- Ectotherms need thermal gradient
- Heat tapes and thermostats may be used
- Light bulbs and heat rocks are inefficient and can be dangerous
- Temperature mosaic (top to bottom, front to back).
- External infrared heat sources that create basking zones.
- Humidity – Too low predisposes to chronic dehydration, dysecdysis, chronic renal problems.
- Excessive associated with development of dermatitis.
- Humidity chambers can be created.
- UV light generally not considered critical.
- Recent study showed certain snakes increase circulating 25 hydroxyvitamin D3 concentrations when exposed to UVB radiation.
Describe the feeding straegy of snakes.
What is the preferred prey source?
What are some common husbandry associated causes of anorexia?
How often should snakes eat?
Feeding and nutrition
- All snakes carnivorous, but diet varies by species
- Some specialized diets.
- Commercial sources recommended to reduce parasite transmission.
- Incorrect prey is common cause of anorexia
- Whole rodents are nutritionally complete, but rodents should be fed nutritionally complete rodent diet
- Frozen thawed preferred - avoid bite wounds/injuries of live prey, humane considerations
- Freezing few days before feeding will also help reduce parasite transmission.
- Live items may cause extensive trauma to snakes if left alone in the enclosure.
- Avoid feeding by hand - radiates heat, avoid bites
- May also be anorexic if appropriate environmental temperature is not provided hat
- Normal not to feed during ecdysis
- Feeding frequency varies by species, age, and season; juvenile and adults - once weekly feedings; babies need 2 feedings a week
- Juveniles may be fed more often (every 5-10 days).
- Adults every 1-2 weeks.
- May also be fasted periodically for 4-8 weeks without harm.
- When cycling a female, more frequent feedings are often done to increase weight prior to the fasting period associated with the gravid state.
- Male snakes will often refuse food during breeding season for weeks to months.
- Snake spp that consume fishes and amphibs will generally eat more often and two to three times a week may be appropriate.
- Many snakes may not feed during gestation and breeding males may have reduced appetite
What is brumation? What snakes do it?
How is it replicated in managed care?
What species can be negatively affected by brumation (meaning they don’t typically do it)?
Brumation
- Temperate zone snakes (colubrids) must be brumated to induce successful reproduction
- Fed well during summer and fall, then feeding is stopped and snakes can pass stool to empty gi tract before cooling cycle
- Cage temperature slowly dropped over several weeks - 2.8 deg C every few days for a total drop of 10-14 deg C conditions the snakes to enter brumation
- Maintained in dark with water, but no food for 3 months
- Then slowly increased temperatures and feed 2-3 weeks later
- Most tropical boas and pythons do NOT require drastic temperature drop (5 deg C) suffices and may only need to occur at night; total darkness not required; tropical snakes prone to respiratory or neurologic disease if too cool
- Neonate temperate zone snakes that are not yet feeding if in good condition can be brumated to induce them to feed after brumation
- No snake should be brumated if not in good physical condition or showing evidence of illness
Describe the ideal preventative medicine protocol for snakes.
Quarantine (F8):
- Progression of infectious dz in snakes may be significantly slower.
- Quarantine periods of at least 90 days are recommended.
- Testing should be targeted toward agents causing chronic dz that may take longer than a quarantine period to manifest, especially those that are environmentally stable with direct LC.
- Greater collection threats.
- Some of the snake pathogens that merit most significant consideration for quarantine pathogen – Adenoviruses, arenaviruses, Chlamydophila pneumoniae, Cryptosporidium spp.
Describe the proper physical restraint of snakes.
What about venemous snakes?
What about large constrictors?
Restraint - (Ch 20 Mader, F8)
- Gentle manual restraint by grasping head immediately behind the mandible. One handler for each 3-4 ft of snake.
- Venomous snakes should only be handled by trained individuals with appropriate equipment (tongs, hooks, tubes, shift boxes).
- Aggressive or unknown disposition - identify and control head; chapter recommends placing thumb and middle finger laterally behind the jaw and index finger on top of the head
- Additional handler recommended for large boids or pythons, even if docile - safety and to support lengthy body
- Physical Restraint (West):
- Never handle lizard spp with tail autonomy by the tail.
- Nonvenomous snakes restrained by grasping the neck caudal to the head while supporting the body with the other hand.
Describe snake anesthesia.
What are the most commonly used methods? What about venemous snakes?
What inhalants are commonly used?
What injectables are commonly used?
How is apnea handled?
What is the preferred analgesic?
Anesthesia and Analgesia (F8)
- Dissociative anesthetics, propofol, local anesthetics, inhalants most commonly used.
- Venomous – Restraint in tube then propofol or chamber/tube induction with gas.
- Isoflurane most common.
- Nitrous oxide has been used as a supplemental agent during induction in monitor lizards to reduce MAC.
- Primary benefit of inhalant anesthetics over injectable agents is more direct control over the anesthetic during the procedure.
- Most snakes will become apneic at surgical plane of anesthesia, need ventilation 6 BPM.
- Recovery should be on room air.
- Propofol – IV, IO, IC; rapid induction and recovery times, ventilation needed.
- With IC injection, study showed lesions in cardiac tissues were mild and resolved after 14 days.
- Alfaxalone – Heavy sedation in one study at 9 mg/kg IV, easily intubated, may be preferable to propofol.
- Less cardiorespiratory depression, shorter induction times, shorter total ax duration.
- Telazol – Low doses have been used for large, aggressive snakes before handling or intubation.
- Snakes show antinociceptive effects in response to butorphanol but not morphine, unlike other reptile groups. Effective dose of butorphanol is much higher than other spp (20 mg/kg).
Describe the approach to a snake coelotomy.
Where is the incision made?
How is ti closed?
What post-op changes to husbandry shoudl be considered?
Ch 97 Snake Celiotomy - Mader
- Avoid incising snake skin near shed cycle - skin softer and more difficult to handle
- Fasting - recommended to minimize diameter of gastrointestinal tract
- Incision made laterally between first two or second and third rows of dorsal scales
- Avoid incising scales if possible
- Avoid midline ventral abdominal vein
- Incision may need to be long due to anatomy
- Coelomic membranes are thin and tend to be relatively transparent
- Consider stay sutures to find again at closer
- Doesn’t hold sutures well
- Simple continuous suture of absorbable monofilament material recommended
- Body wall closed with a simple continuous monofilament absorbable suture
- Skin closed using everting pattern with horizontal mattress sutures of a nonabsorbable monofilament suture
- Everting pattern - recommended due to keratinized skin’s tendency to invert à reduced contact of cut surfaces à poor healing
- Orient knots dorsally to help minimize adhesion of substrate debris to knots
- No or limited access to submersion of incision in water recommended for 14 days post-op
- Tissue glue around incision site - may reduce contamination during healing process in aquatic species
- Suture removal – typically 6 weeks post-op
- Surgery may hasten shed cycle, may shed sutures earlier
- Changes in husbandry, such as use of a paper substrate to increase cleanliness, postop fasting, reduction in prey size to reduce the incidence of dehiscence, and increases in temperature within POTZ to accelerate healing recommended
Describe the following surgical approaches in snakes:
Coeliotomy
GI Surgery
Dystocia
Subspectaceular Abscess Drainage
Surgery (F8):
- Presurgical workup should include PE, CBC, chem.
- Supplemental heat should always be provided.
- Coeliotomy most common surgical procedure.
- Large abdominal vein runs along ventral midline.
- Approach should be between the second and third rows of lateral scales.
- Closure in two layers – body wall and skin. Skin is holding layer.
- Everting suture pattern for skin.
- One study showed polyglyconate and poliglecaprone were the least reactive materials.
- Remove sutures 4-8 wks after surgery.
- GI surgery – FB, management of intestinal prolapse or intussusception, excision of masses or granulomas, relief of impaction.
- Serosa-to-serosa contact for closure of GI incisions.
- Two layer closure ideal but may not be possible in small snakes. Can use a serosal patch.
- Coelomic cavity should be irrigated with warm, sterile saline after GI closure.
- Dystocia – Generally follicular.
- Salpingotomy indicated in reproductively valuable animals, where noninvasive techniques have failed, or if rads show natural passage not possible.
- Incision should be in avascular region of the oviduct. May need more than one incision to access all eggs or fetuses.
- Subspectacular abscesses – Often from ascending infections within oral cavity.
- Excision of spectacle to gain direct access.
- Small triangular wedge, allow for drainage.
- Topical antibiotic three to four times daily to manage infection.
- Spectacle will regenerate but the original incision must remain open until infection is under control.
Describe gout in snake.
How do the kidneys appear on gross necropsy? What about histo?
What is the most common cause of gout in snakes?
Where is the first anatomical site to have urate deposition?
- Gout
- Kidneys swollen- multifocal to miliary white/tan pinpoint nodules
- Impression smears can differentiate urate stasis (sexual segment streaking in males) from true renal gout
- Radiating urate tophi will be present in gout (vs round or amorphous urates with urate stasis)
- Histo: tophi appear as empty spaces and are surrounded by epithelioid macrophages, multinucelated giant cells and heterophils
- Secondary gout associated with dehydration is most common in snakes
- Uric acid deposition in kidneys usually precedes other tissues (pericardial sac, pleura, serosa of liver, etc)
- Articular (intervertebral) gout is not as common, but can occur
What is vertebral osteopathy in snakes?
What lesions are observed?
What are the proposed etiologies?
- Chronic vertebral osteopathy
- Proliferative, degenerative, inflammatory lesions in vertebral bodies, intervertebral joints, and ribs
- Bony remodeling, new bone and fibrocartilage formation, sclerosis, vertebral and costal spondylosis and ankylosis, degeneration of the articular cartilage, osteomyelitis, osteoarthritis, osteonecrosis, pathologic fractures
- Irregular patches of woven and lamellar bone with mosaic reversal lines
- Etiologies: trauma, viral, nutritional (hypervitaminosis A and D), chronic inactivity (confinement), chronic or resolved bacterial infections
- Salmonella (S. enterica arizonae associated with osteotropism in colony of ridgenose rattlesnakes), Pseudomonas, Staphylococcus
What are some common nutritional diseases of snakes?
What about piscivorous snakes?
What about egg-eating snakes?
- Nutritional diseases
- Both temp extremes will lead to anorexia and regurgitation if food is taken.
- Obesity is the most common nutritional disorder observed in captive snakes (F8).
- Reducing wt of obese snake should be done slowly over 6-12 months.
- Rapid reduction of food may lead to hepatic lipidosis.
- Captive snakes should not be fed wild-caught food items.
- Rodent suppliers who use pesticides to manage ectoparasites in their operation should be asked to stop use of pesticides a min of 3 wks before shipment.
- Avoid NSHP by dusting with calcium or vitamin sources for snakes fed neonatal rodents.
- Piscivorous snakes vet strictly fish may be predisposed to thiamine and vit E deficiencies.
- Neuro signs, loss of righting reflex, abnormal locomotion, muscle tremors, blindness.
- Vit E deficiencies leading to steatitis may occur when snakes are fed fish high in PUFAs.
- Feeding variety of fish spp and not a high percentage of fatt, cold water fish, is an effective prevention strategy.
- Egg eating - biotin deficiency caused by uncooked avidin binding it
How often are snakes diagnosed with neoplasia compared to other reptiles?
What are the most common hematopoietic tumors?
What are the most common oral tumors?
What are the most common GI tumors?
What are the most common renal tumors?
What are the most common integumentary tumors?
- Neoplastic - more often diagnosed with neoplasia than other reptile species
- Lymphoma - usually multicentric, though esophageal MALT reported
- Lymphocytes most commonly large and blast-like
- CD3+ T-cell lymphomas seem to be most common (biased as B-cell markers have limited diagnostic utility)
- Other hematopoietic: leukemia, mast cell tumors, histiocytic origin round cell tumors
- Squamous cell carcinoma
- solitary or multifocal; common in oral cavity
- Invasive, locally destructive, metastasis uncommon
- Association with chronic inflammation (stomatitis) has not been fully examined
- Other oral cavity tumors: fibrosarcoma, amelanotic melanophoroma, oral tumors of odontogenic origin, ameloblastoma
- Gastric, intestinal, cloacal adenocarcinomas
- Gastric: locally invasive and expansile masses - tubulopapillary arrangements of columnar to cuboidal neoplastic epithelial cells with scirrhous response
- Intestinal are common in colubrids, distal si and colon common sites
- Signet ring or mucinous cell morphology
- Pancreatic and pancreatic duct adenocarcinomas - well differentiated, but can be aggressive and metastasize
- Exocrine pancreas adenomas and nodular exocrine hyperplasia are a common incidental finding
- Renal adenocarcinomas
- large, solitary tumors composed of tubules lined with epithelial cells and scirrhous stroma that expand and disrupt normal parenchyma
- Urate tophi often present within neoplastic tubules and desmoplastic stroma
- Large cystic cavities with urine and urates can be seen
- Renal tubular adenomas - inicental finding - solid nodular foci of tubular proliferations that may compress adjacent tissue but lack desmoplastic response
- Reproductive - varial metastases
- Ovarian carcinoma, sarcoma and benign granulosa cell tumors
- Oviductal adenocarcinomas - exophytic, papulary, composed of cords of neoplastic cells that may have areas of hemorrhage, necrosis, and inflammation
- Integument:
- Squamous cell carcinomas most common with cloacal region (hemipenes, cloacal glands, cloacal skin)
- Chromatophoromas
- melanophoromas most common (gray or black composed of neoplastic spindled cells with prominent black cytoplasmic granules); variable activity (some invasive with intravascular and visceral mets)
- Iridophoromas: grossly white to light gray dermal masses of spindle cells with golden brown to yellow/green cytoplasmic pigment (most often benign)
- Xanthophoromas
- Cutaneous soft tissue sarcomas - locally invasive, interlacing bundles and streams of neoplastic spindle cells (fibrosarcomas) most common
- Many other benign and malignant neoplasms (smooth muscle, endothelial, mesenchymal, hepatic, biliary (often cystic), thyroid and parathyroid adenomas, pheochromocytomas, interrenal (adrenocortical) adenocarcinomas, intratracheal chondromas (airway obstruction in ball pythons), hemangiosarcomas of heart and spleen, etc
- Lymphoma - usually multicentric, though esophageal MALT reported
How does herpesvirus affect snakes?
What species are susceptible?
What lesions are suggestive?
- Herpesvirus infections uncommon - cobras, kraits
- Cobras: inflammation, degeneration, necrosis of venom gland epithelium associated with decreased venom production or poor quality venom, hepatic necrosis.
- Suggestive of herpesvirus: Hepatocellular necrosis with amphophilic intranuclear hepatocellular inclusions in clutch of boa constrictors concurrent with pancreatic, renal, and adrenal intranuclear inclusions
- All herpesviruses in reptiles and birds are in the subfamily Alphaherpesvirinae.
- Known for latency, should be considered infected for life.
What is the etiologic agent of inclusion body disease?
What are the clinical signs?
What are the lesions? Describe the inclusion bodies.
Which snakes have acutely progressive disease? Which have chronic disease?
How is this disease transmitted?
Are tehre any associated clinicopathologic changes?
How is this disease diagnosed and managed?
- Inclusion body disease (IBD) – Arenaviridae.
- Global, transmissible, progressively fatal
- Captive boas and pythons
- Arenavirus implicated as cause
- Central nervous system abnormalities- flaccid paralysis, stargazing, torticollis, chronic regurgitation, loss of body condition
- Some individuals succumb in weeks while others survive for months - challenge in captive collections
- Variably sized, eosinophilic to amphophilic, intracytoplasmic inclusions
- With more rapid progression (particularly pythons), inclusions typically in CNS)
- With more chronic disease (boa constrictors), inclusions throughout body, lymph and blood
- Disease progression may take months or years.
- Secondary infections common, immunosuppression
Mader 2019 – Ch. 154 Inclusion Body Disease
- Definition
- Arenavius = enveloped RNA virus
- Inclusion body disease → chronic, multisystemic wasting disease
- Primarily affects boids but also colubrids and vipers
- Snake mite may be vector
- Clinical Signs
- Regurgitation (common in boas not pythons), incoordination, disorientation, opisthotonus, torticollis, lack of righting reflex
- Secondary: pneumonia, stomatitis, lymphoproliferative/neoplastic dz
- Ball pythons often die within weeks
- Boas die after months to years
- Acute disease → Leukocytosis, lymphocytosis, lower total protein and globulin, elevated AST
- Gross Lesions:
- Splenic and pancreatic atrophy
- Intracytoplasmic eosinophilic to amphophilic inclusions
- In multiple tissues in boas
- In CNS in pythons
- Diagnosis
- RT PCR
- IHC
- Inclusions on blood smear
- Histo
- Virus isolation
- Prognosis and Prevention
- No treatment; euthanasia recommended
- Poor prognosis
- Quarantine for > 6 months, repeat testing
What are teh clinical signs of nidovirus in snakes?
What species ahve been reported with disease.
What lesions have been documented?
- Nidoviruses
- Fatal respiratory disease in ball pythons and an Indian python reported
- Open mouth, labored, audible breathing; copious mucoid to exudative oral/glottal/tracheal discharge
- Catarrhal and necroexudative stomatitis, tracheitis and pneumonia present - expanded faveoli, mucus present in gi tract
- Epithelial hyperplasia and necrosis with lymphoplasmacytic and heterophilic inflammation seen in oral cavity, nasal cavity, trachea, esophagus, lungs
- Profound pneumocyte hyperplasia
What are the two paramyxoviruses affecting snakes?
What species are affected?
What clinical signs do these viruses cause?
What gross lesions are present? What histologic lesions?
What are the inclusion bodies?
How is this disease transmitted?
How is it diagnosed and managed?
- Paramyxoviruses (ZPP) - primarily viperids and crotalids, others susceptible
- Respiratory disease in captive snake (OPMV)
- Lungs - thickened, edematous; hemorrhage and necroexudative material in airways throughout lung (hemorrhage can also occur in oral/nasal cavities, glottis, esophagus and coelomic cavity
- Similar histologic changes to other viral pneumonia - pneumocyte hyperplasia and inflammation
- Presence of both pulmonary epithelial syncytia and eosinophilic intracytoplasmic inclusion bodies within pneumocytes are diagnostic features along with the absence of segmental esophagitis can help differentiate
- Pancreatic inflammation and necrosis may be present
- Concurrent neurologic disease (meningoencephalitis, lymphocytic perivascular cuffing, demyelination, axonal and neuronal degeneration, intracytoplasmic gleal and intranuclear neuronal viral inclusion bodies
- Neurologic, respiratory, and acute immunosuppressive diseases in snakes.
- Two clades: Ferlaviruses and Sunshine Virus.
- Temperature dependent.
- PCR with sequencing recommended for most clinical applications (F8).
Mader 2019 – Ch. 158 Paramyxoviruses (Ferlaviruses)
- All partially characterized reptile paramyxoviruses (ssRNA) are within genus Ferlavirus, family paramyxoviridae.
- Except: Sunshine virus – Australian pythons.
- Documented mainly in snakes, also lizards and chelonians.
- Clinical presentation:
- Variable – No CS to severe resp dz with or without tracheal exudate.
- Neurologic signs.
- Gross lesions:
- Range from none to caseous-necrotic material in lungs, hemorrhages, and dermatitis.
- Microscopic lesion:
- Proliferative interstitial pneumonia with occasional intracycoplasmic eosinophilic inclusions is characteristic of Ferlaviruses infection
- Sunshine virus – severe spongiosis of white matter of hindbrain.
- Chelonian paramyxovirus infection – pneumonia, degenerative liver dz, stomatitis, dermatitis.
- Transmission:
- Intratracheal administration leads to disease.
- Vertical transmission also considered for Sunshine vvirus.
- Dx confirmation:
- Serology, molecular tests, VI, IHC, histo, EM.
- Most common serologic test – Hemagglutination inhibition.
- Most common molecular test – RT-PCR, targets L gene.
- Specific PCR available for Sunshine virus.
- Can detect Ferlavirus RNA in tissues as early as 4 days post infection, animals remain positive at least 49 days.
- Lung, SI, pancreas, brain tissues of choice for post mortem dx.
- Antemortem – Combine RT-PCR and viral isolation on tracheal wash, viral detection as early as 16 days post infection. Cloacal swabs may be positive as early as 28 days post infection.
- HI titers require minimum of 16 days, becomes more robust at 28 days.
- Ideal dx – molecular, serologic, histopathologic investigations and VI.
- Serology, molecular tests, VI, IHC, histo, EM.
- TX – None; Supportive care.
- Px and prevention:
- Quarantine up to 6 mos while carrying out repeated molecular and serologic tests.
- Isolation and testing of reptiles with clinical signs.
- Prognosis is guarded to poor.
What are the clinical signs associated with ophidiomycosis?
Is there a seasonality to clinical signs?
What lesions are found at necropsy?
Clinical presentation:
- CS: focal or moultifocal and coalescing scale necrosis, esp. on head and face, discolored scutes and scales with epidermal brown crusting, sometimes hyperkeratosis
- Very rarely dissemination and fungicemia
- Swelling causes by granulomas in subcutis
- More frequent ecdysis
- Lesions can impede hunting and feeding and cause behavioral changes like seeking open areas and exiting hibernacula during winter
- In rat snakes (and other colubrids); swelling along body caused by subcutaneous mycetomas
- If mild lesions, can improve with shedding during summer months (increase in T˚ leads to more efficient immune response), but if lesions begin at ingress (beginning of winter), dropping T˚ favor fungal growth in increasingly torpid animals –> worse prognosis although some survive
Lesions
- Histo: necroulcerative, heterophilic, ulcerative dermatitis; overlying serocellular crusts with necrotic debris and proteinaceous material, parallel walled branching septate hyphae; along surface of crusts - cylindrical fission arthroconidia may be present (similar to CANV)
- Mild dermatitis may resolve, severe cases -> facial distortion, deep chronic granulomatous heterophilic inflammation associated with severe osteolysis and osteomyelitis
- Disseminated infections with widespread visceral granulomas
What is the ocular nematode of ball pythons?
What lesions are present?
Serpentirhabdias dubielzigi - ocular disease in captive ball pythons: opaque spectacles, swelling of oral/facial/periocular tissues; subspectacular space expanded by inflammatory and proteinaceous debris as well as parasites of all life stages
What are the clinical signs associated with cryptosporidiosis in snakes?
What gross and histologic lesions are generally present?
What cryptosporidium species are present in snakes? Do they cause different disease?
How is this disease diagnosed and controlled?
- Cryptosporidiosis - Cryptosporidium serpentis
- Enlarged and firm stomach - may cause bulging of body wall
- Gastric mucosa thickened with prominent rugae and mucus accumulation
- Gastric mucosa hyperplastic with more connective tissue in the lamina propria and submucosa; gastric glands dilated, atrophy of granular and serous cells, hyperplasia of mucus cells, intracellular extracytoplasmic cryptosporidial oocysts attached to microvillar surface
- C. saurophilum (C.varanii new name) primarily in lizards can also be found in snakes - chronic enteritis, crypto is at apical margin of enterocytes
- Monogenous – Entire LC in one host. Transmission is fecal-oral. Also fomites.
- Thick-walled sporozoite resistant to desiccation and most disinfectants.
- Only ammonia 5% and formal saline are effective against oocysts.
- Direct LC.
- C. serpentis has gastric tropism.
- Poor growth, wt loss, regurgitation, gastric hypertrophy and midbody swelling.
- C. varanii usually present with wasting, diarrhea without regurgitation.
- Intestinal disease.
- Gallbladder and intra and extrahepatic bile ducts contain organisms.
- Antimortem dx by demonstrating oocysts in mucus-coated regurgitated food, gastric lavage, impression smears of biopsy samples, or in feces by using AF stains. PCR with speciation.
- During quarantine, AF screening of fecal samples with PCR for any positive results should be considered.
- Endoscopic bx or laparotomy samples may be evaluated for the presence of the organism.
- Tx not rewarding, not effective.
- Culling confirmed cases from collection and prevention are best control methods.
What are the two genera of pentastomids affecting snakes?
How are these diagnosed and treated?
- Pentastomids.
- Obligate parasites of lower respiratory tract of vertebrates.
- All require IM host for LC, zoonotic potential for some spp to humans.
- Armilifer and Porocephalus.
- Dx with eggs in lung washes or feces, survey rads.
- Larvae possess hooklets.
- Tx in larger snakes with endoscopic removal. Some chemotherapeutic agents have been suggested.
- Fenbendazole may cause significant bone marrow suppression and damage to gut epithelium in many snake spp.
Describe the management of scent gland impaction in snakes.
What diseases are associated with impaction?
Are any demographic groups overrepresented?
- Presentation of a swelling caudal to the cloaca was similar in all six snakes and led to the clinical diagnosis of a cloacal scent gland impaction
- No other systemic signs aside from obstipation
- Infection (66.7%), neoplasia (16.7%), and mineralization (16.7%) of the glands were associated with the clinical impactions in 83.3% snakes
- Colubrids, older snakes, and female animals over-respresented
- Medical management often unrewarding or impossible
- Surgical excision recommended
- Introduction of a small probe, wax, or synthetic resin may help to better delineate the gland before resection recommended
- Ligate gland as close as possible to proctodeum to remove all possible glandular tissue and allow histopath of excretory duct
Couture, É. L., Lung, N. P., Lair, S., & Ferrell, S. T. (2018). Ophidian Cloacal Scent Gland Impaction and Surgical Excision: A Case Series in Six Different Snake Species. Journal of Herpetological Medicine and Surgery, 28(3-4), 81-88.
A recent paper described a potentially fatal complication following cardiocentesis in snakes?
What occurred in this case?
JHMS 32.2 (2022)
Cardiac Tamponade Following Cardiocentesis in a Ball Python (Python regius)
Jessica R. Comolli, Brittany McHale, Spencer Kehoe, Jörg Mayer
Key Points:
- Cardiocentesis generally thought to be a safe way to collect blood from snakes
– Previous studies in pythons showed minimal histological / clinical side effects even when multiple cardiocenteses performed.
- This was a case report of a ball python that died shortly after cardiac venipuncture
– Snake was anesthetized and cardiocentesis performed by an experienced tech
– Swelling in area of heart seen just after cardiocentesis, followed quickly by cardiac arrest
– Necropsy detemined case of death to be acute cardiac tamponade secondary to hemopericardium
– Snake had mild respiratory disease but no evidence of pre-existing cardiac diseaese
Take home: Hemopericardium and fatal cardiac tamponade are rare potential side effects of cardiocentesis in snakes
A recent paper described a case of kidney prolapse in. a kingsnake.
What are the most common type of organ prolapses?
- How are they typically treated?
- What conditions are they associated with?
What was found on necropsy of this individual?
What are some common causes of renal disease in snakes?
JHMS 32.4 (2022).
Cloacally Located Kidney Prolapsing in a Kingsnake Species (Lampropeltis spp.)
Jade Hardy, Ethan Biswell, Nicole Hardy, Curtis Eng
Key Points:
- Organ prolapses through the cloaca are a relatively common occurrence
– Treatment: reduction or resection
– Prolapse associated with: straining (intestinal disease), mating, neoplasia, urinary calculi, cystitis, metabolic bone disease, obesity, muscular weakness
– Distal GI tract, urinary bladder, phallus/hemipenes and oviduct are most common prolapsed organs
- 8yo F Kingsnake with caudal coelomic swelling - multiple firm masses palpated
– Enema administered, snake passed a pedunculated mass
– Died 72h after procedure with no clinical signs
- Necropsy: Mass confirmed as kidney with bacterial granulomas and gouty tophi
– Multifocal granulomas present in colon and oviducts
- Suspect that an enteritis lead to breach of colonic wall and then spread to kidney and repro
– Cloacal tissue healed behind the kidney, trapping it in cloaca and causing fecal buildup cranial: No signs of acute rupture of the cloaca, ligation around pedunculated stalk was in the cloaca
- Renal Dz:
– Bacterial nephritis caused by: Salmonella, Pseudomonas, Microsporidia, Spironucleus, Klossiella and Myxozoa
– Gout: dehydration most common cause, excessive dietary purines and nephrotoxic drugs
- Bacterial Salpingitis: Pseudomonas and Salmonella most common causes
A recent paper described complete unilateral maxillectomy in columbian boas.
What is the scientific name of the columbian boa?
Describe the unique maxillary anatomy of snakes.
Why was this procedure being performed in these snakes?
What local anesthesia was performed for these procedures?
What was the surgical approach?
JZWM 53.3 (2022)
COMPLETE UNILATERAL MAXILLECTOMY IN A COHORT OF FIVE COLOMBIAN BOAS (BOA IMPERATOR)
Clément Paillusseau, Frédéric Gandar, Lionel Schilliger
Key Points:
- Snake skulls unique: absence of a mandibular symphysis, presence of a mobile quadrate bone and, in some species, a high degree of mobility of the maxillary bones allowing independent movement of toothed bones facilitating large prey ingestion; Pleurodont teeth .
- Because the maxilla is attached to neighboring bones by soft tissues in pythonids and boids, postoperative healing can be maximized, as no osseous tissue resection is necessary
- Using a lateral gingival approach, the maxillo–prefrontal, maxillary–palatine, and maxillo–ectopterygoid attachments were transected, and the maxillary bone removed
- complete unilateral maxillectomy in boids does not substantially affect food intake when snakes were fed small, dead prey
- Surgical dehiscence seen in one animal - risks = more friable gingiva in snakes, oral flora, mastication trauma (reduce with monofilament suture, continuous pattern, taper needle not cutting, fasting patient for period post-op to allow healing, antimicrobials - gram neg)
- Nerve block for maxillectomy: trigeminal nerve (V) contributes to sensory and motor innervation of the head in snakes. It is divided into the ophthalmic (V1), maxillary (V2), mandibular (V3), and pterygoid (V4). Maxillary branch innervates maxilla - emerges from the anterior prootic foramen (block here is contraindicated due to risk of iatrogenic lesion), distal block at infraorbital foramen yields incomplete block of maxilla, therefore local infiltration/periosteal infiltration recommended
Take home: Unilateral maxillectomy may be viable alternative to medical management for osteomyelitis in boid snakes
A recent study characterized the ultrasonographic evaluation of coelomic fluid in healthy corn snakes.
What is the scientific name of the corn snake?
Coelomic fluid in snakes can be indicative of what pathology?
What region of the snake is likely to contain coelomic fluid?
What is the cytological characteristic of this fluid?
Hepps Keeney CM, Cohen EB, Lewbart GA, Ozawa SM.
ULTRASONOGRAPHIC EVALUATION OF COELOMIC FLUID IN HEALTHY CORN SNAKES (PANTHEROPHIS GUTTATUS).
J Zoo Wildl Med. 2023 Mar;54(1):65-72.
Key Points:
- Free coelomic fluid in snakes can be from pathology (cardiac dz, neoplasia, renal or hepatic failure, and trauma); small volume reported as a normal finding; however, no reports on what volume or appearance would be considered normal
- R3 (region with the stomach, splenopancreas and portion of intestine) in corn snakes is most likely to contain coelomic fluid in a normal animal
- Ceolomic fluid can be normal in healthy snakes and is transudative. If cells present - predominantly lypmphocytic.
- Also a reference paper for POCUS in snakes
A recent study described the ejaculate of lancehead pitvipers.
What genus do these vipers belong to?
How did the gonadosomatic index vary throughout the year in these species?
How did sperm count change throughout the year?
ZB 2023 42(1) 119-132
Ejaculate characteristics over seasons in five species of lancehead pitvipers Bothrops spp
Key Points:
- Gonadosomatic Index (GSI) in Brazilian lanceheads did not vary throughout the year, whereas it increased in the autumn for Common lanceheads, Jararacussu, and Whitetail lanceheads. On the other hand, GSI declines occurred at different seasons for these three species, taking place in spring for Jararacussu and Whitetail lanceheads, and in winter for Common lanceheads.
- Sperm count: only Jararaca and Whitetail lancehead demonstrated seasonal differences with increases during winter and spring, respectively
- Seasonal variations in GSI did not seem to markedly impact sperm production or quality
Takeaway: Although all snakes used in the study were kept within similar protocols of temperature, food, and humidity, the data suggest they can still maintain their reproductive characteristics according to their biome of origin, even if they are born in captivity.
