Difference between revisions of "Snake Physical Examination"

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[[Image:Steth_crop.jpg|400px|thumb|right|(Copyright © RVC)]]
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[[Image:Steth_crop.jpg|200px|thumb|right|©RVC and its licensors, Peer Zwart and Fredric Frye. All rights reserved]]
 
==Introduction==
 
==Introduction==
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The physical examination involves observation of the snake, taking measurements and a thorough methodical area by area examination. Many techniques are similar to other animals, but before examining the snake ask the owner if it is accustomed to being [[Snake Handling and Restraint|handled]]. A veterinarian who is inexperienced with reptiles may focus on the presenting signs and end up treating exclusively secondary problems.  Stomatitis and rectal prolapse for example are secondary conditions where a full examination with husbandry review including [[Snake Housing|housing]] and [[Snake Feeding and Digestion|nutrition]] is vital to determine the principal problem.
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The physical examination involves observation of the snake, taking measurements and a thorough methodical area by area examination. Many techniques are similar to other animals, but before examining the snake ask the owner if it is accustomed to being handled.  [[Snake Handling and Restraint|See here]] for information on handling and restraint of snakes. A veterinarian who is inexperienced with reptiles may be likely to focus on the presenting signs but then can end up treating exclusively the secondary problems.  Stomatitis and rectal prolapse are secondary conditions where a full examination with husbandry review, including [[Snake Housing|housing]] and [[Snake feeding|nutrition]], is vital in determining the principal problem.
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===Observation===
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==Observation==
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Snakes should have active tongues that are sampling scent particles in the atmosphere.  Normal movement should be observed although allowances must be made for any chilling effect in transit since this will reduce the patient's metabolism and give a misleading impression of lethargy and lack of strength.  The righting reflex should be tested since poor reactions can be a result of weakness and not necessarily neurological disease.  Respiration, including rib movements and any sounds produced.  Be aware of hissing noises arising from agitation that are not a result of respiratory infection.
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Snakes should have active tongues that are sampling scent particles in the atmosphere and passing them to the [[Snake Special Senses|Jacobson's organ]].  Normal movement should be observed although allowances must be made for any chilling effect in transit since this will reduce the patient's metabolism and give a misleading impression of lethargy and lack of strength.  A healthy snake will have adequate muscle tone and grip the clinician's hands.  Review how to correctly handle and restrain a snake [[Snake Handling and Restraint|here]].  There will be a level of activity befitting the particular [[:Category:Snake Species|species]].  A sick snake usually remains limp.  The righting reflex should be tested since poor reactions can be a result of weakness and not necessarily neurological disease.  [[Snake Neurological System|Neurological function]] can be assessed by checking head position, body posture, cloacal tone and righting reflexes. [[Snake Respiratory System|Respiration]], including rib movements and any sounds produced should be noted.
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===Body condition===
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Weight of the snake should be taken at every examination, as should snout-vent lengths.  Obese snakes have increased fat deposition on the last third of the body before the cloaca.  Cachectic snakes with significant loss of muscle mass show a prominant dorsal spine and ribs, and the body shape looks more triangular in cross section.
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==Skin==
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[[Image:0051_BLISTER_DISEASE_PYTHON_ed.jpg|250px|thumb|right|'''Blisters on skin'''©RVC and its licensors, Peer Zwart and Fredric Frye. All rights reserved]]
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Examine under a bright light and with a hand lens if necessary.
  
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==Organ positions==
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Examine for:  
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The organisation of internal structures varies between snake families and genera.  However it is important to know the approximate position of the organs during a physical examination.  The following is a generalisation if the snake's body is divided into thirds from snout to vent:
 
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*'''Cranial third''' - contains the trachea, oesophagus and heart.
 
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*'''Middle third''' - contains the liver, lung and stomach.
 
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*'''Caudal third''' - contains the small intestine, the triad of pancreas, spleen and gallbladder, the adrenal glands, large intestine, gonads, reproductive tract, kidneys, fat body and [[Cloaca|cloaca]].  Behind the [[Vent|vent]] are the musk and, if the snake is a male, the [[Hemipenes|hemipenes]].
 
  
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'''Find out more about snake anatomy in sections covering the''' [[Snake Digestive System|digestive]], [[Snake Respiratory System|respiratory]] '''and''' [[Snake Reproductive System|reproductive]] '''systems'''.
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*Ectoparasites
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==Skin==
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*Trauma due to fighting, mating or thermal burns
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[[Image:0051_BLISTER_DISEASE_PYTHON_ed.jpg|250px|thumb|right|'''Blisters on skin''' (Copyright © RVC)]]
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*Discoloration (previous scars, injection sites)  
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Check the general appearance of the skin.  The skin should be bright and shiny.  Assess elasticity and skin tenting. Dehydrated snakes show outwardly directed folds of skin and [[Snake Dysecdysis|dysecdysis]].  Examine the skin both dorsally and ventrally for retained shed, blisters, pustules, burns, discharges, erythema, pettechi, ulcers, loss of scales, lacerations and swellings. Examine for ectoparasites, especially [[Snake Mites|mites]] that tend to hide under scales of the skin.  Brushing the body of the snake over a white sheet may be helpful in checking for mites. The snake's body can be palpated by simply moving the hand, both dorsally and ventrally, down its length.  Identify any [[Snake Lumps and Bumps|masses and swellings]] under the skin.  Subcutaneous lumps are usually due to abscesses but neoplasia and the second-stage cysts of cestodes can also be encountered in snakes.
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*Dysecdysis - retained skin is often dry and brown while normal ecdysis occurring in a piecemeal fashion is flexible and transparent. Retained skin is a focus for infection and acts as a tourniquet on the tail tip and digits leading to ischaemic necrosis
 +
*Examine the scales for loss, scabs, blisters and haemorrhages, ensuring the ventral scales are inspected
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*Assess for abnormal masses, swellings or bruised areas
 +
*Assess skin elasticity
 +
*Skin folding indicates dehydration, cachexia. Assessment of dehydration in reptiles is analogous to mammals. With 5-8% dehydration there is loss of skin elasticity with a wrinkled appearance. With more severe dehydration (10-15%) the eyes are sunken and the mucous membranes become dry and sticky (consider that the oral cavity of most reptiles is relatively dry compared with mammals).
  
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'''Find out more about [[Snake Skin|snake skin]]'''.
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Find out more about [[Snake Skin|snake skin]]
  
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[[Image:Boa_with_dys_ed.jpg|200px|thumb|right|'''Dysecdysis''' (Copyright © RVC)]]
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Find out more about [[Snake Skin Diseases|snake skin diseases]]
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[[Image:Boa_with_dys_ed.jpg|200px|thumb|right|'''Dysecdysis'''©RVC and its licensors, Peer Zwart and Fredric Frye. All rights reserved]]
 
===Shedding===
 
===Shedding===
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[[Ecdysis]] (shedding) generally takes place every 14 days although this is dependent on many variables such as environment, age and size of snake.  Snakes shed their entire skin in one piece, including the [[Snake Eye|spectacles]], although large snakes greater than 3m in length may shed their skin in incomplete sections.  Prior to ecdydsis, a snake will become anorectic and handling may be hazardous to the animal at this time if the underlying epidermis is damaged.
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Ecdysis (shedding) generally takes place every 14 days although this is dependent on many variables such as environment, age and size of snake.  Snakes shed their entire skin in one piece, including the spectacles, although large snakes greater than 3m in length may shed their skin in incomplete sections.  Prior to ecdydsis, a snake will become anorectic and handling may be hazardous to the animal at this time if the underlying epidermis is damaged.
 
==Head==
 
==Head==
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Initially check that the snake moves and supports its head normally and that it investigates its surroundings with an active flicking tongue.  Examine the rostrum for abrasions that may indicate an unsuitable cage.  Check the nares for patency and discharge.  Examine the [[Snake Special Senses|heat-sensing pits]], the crevice around the spectacle and the skin between the scales for [[Snake Mites|ectoparasites]] or [[Snake Dysecdysis|retained skin]].  Palpate the jaws for any abnormal swellings.
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===Nares===
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The nares should be clear and free of discharge and retained shed.
 
===Eyes===
 
===Eyes===
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The [[Snake Eye|eyes]] are usually considered as a barometer of general health and environmental conditions; therefore a full ophthalmologic examination should be performed in all cases. Observe the movement and general position of the eye within the socket. The optic nerve and other cranial nerves associated with eye function are assessed by observing the snake's reaction to movement and by normal and co-ordinated eye movements.  Strabismus may indicated dysfunction.  Bulging eyes may result from retrobulbar or periocular cellulitis, absecesses or neoplasia. Inspect the spectacles.  They should be clear, not wrinkled, distended or discoloured although they are normally bluish-white prior to shedding. The subspectacular space should be clear.  Check for any signs of conjunctivitis.  Remember that the mydriatics are not useful and that there is no consensual light reflex.  
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The eyes are usually considered as a barometer of general health and environmental conditions; therefore a full ophthalmologic examination should be performed in all cases.  
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* Other diagnostic tools, such as tonometry (measurement of the intraocular pressure), stains, cytology, bacteriology, histopathology and electron microscopy, in addition to routine diagnostic tools ([[Lizard and Snake Haematology|haemotology]], [[Lizard and Snake Biochemistry|biochemistry]], [[Lizard and Snake Imaging|radiology]] and [[Lizard and Snake Imaging|ultrasound]]) can also be used to detect an ocular disease or underlying problem in snakes.  
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[[Image:Boa_stomatitis_ed.jpg|200px|thumb|right|'''Ulcerative stomatitis''' (Copyright © RVC)]]
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* Following a general assessment of the eye, a more detailed examination should be performed using a form of focal illumination and a magnification system.  
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* Examination of the ocular fundus to assess the retina (fundoscopy) can be carried out using a direct or indirect ophthalmoscope.
 +
* Mydriasis can be attempted either through general anaesthesia or intracameral injection of neuromuscular blocking agents such as curare or d-tubocurarine. These agents can also be applied topically; however their effectiveness may be affected by the variable corneal penetration of the drugs.  
 +
* Other diagnostic tools, such as tonometry (measurement of the intraocular pressure), stains, cytology, bacteriology, histopathology and electron microscopy, in addition to routine diagnostic tools (haemotology, biochemistry, radiology and ultrasound) can also be used to detect an ocular disease or underlying problem in snakes.
 +
*Retained spectacles are a concern.  They should be clear with no signs of subspectacluar disease.  
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[[Image:Boa_stomatitis_ed.jpg|200px|thumb|right|'''Ulcerative stomatitis'''©RVC and its licensors, Peer Zwart and Fredric Frye. All rights reserved]]
 
===Oral cavity===
 
===Oral cavity===
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The oral cavity is fairly easy to evaluate once the mouth is open.  Use an object to gently open the mouth without damaging the delicate gingiva and teeth.  Do not use any cotton since it snags on the caudally curving teeth.  The normally pale and pinkish-white gingiva should be glistening and moist with no petecchiation, excess salivation or oedema.  Excessive saliva in the oral cavity suggests pneumonia or gastrointestinal upset.  [[Snake Vesicular Dermatitis|Mouth rot]] when present varies from mild erythema to a generalised stomatitis with necrotic tissue.  The tongue and its sheath should be examined.  Check the glottis for any discharge.  Check the patency of the internal nares.
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*The oral cavity should be opened using a soft, pliable speculum
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*Mucous membranes should be pale to pink and free of thick ropey mucous
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==Musculoskeletal==
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*Evaluate the tongue for movement
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Assess the bulk and tone of the muscles first.  The body should be rounded.  With emaciation it becomes triangular and the spine and ribs more prominent.  Then assess [[Snake Locomotion|locomotion]] on a rough surface.  Normal posture and coordination should be evident.  Check the righting reflex.  A defect in the vestibular system or hypothiaminosis may result in rolling and an inability to right.  The spine and ribcage should then be palpated for swellings that may be associated with abscesses or fractures.
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*The glottis should be gree of discharge
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==Auscultation/cardiovascular==
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*Examine the teeth for fractures
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In colubrids and boids the heart is located in the cranial third of the body and the lung is in the middle third.  The use of a moistened gauze sponge over the stethoscope will help to eliminated the grating noise against the scales.  Special attention should be paid to abnormal sounds and symmetry.  Sometimes the presence of mucous can be detected.  Defensive hissing must be differentiated from pathologic respiration.
 
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==Coloemic cavity==
 
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Examination of the coelomic cavity is possible in most small snakes by palpating ventrally between the ends of the ribs.  Large snakes are difficult to palpate because of their musculature.  There should be no palpable swellings and if they do occur their position can indicate the organ involved.  The heart can be palpated in the cranial third and the liver lies at a distance caudally in boids and colubrids because of their caudal lung.  Caudal to the liver the gall bladder can be palpated on the ventral midline.  It is possible to palpate the ingesta in healthy snakes while anorexic individuals will feel empty of doughy.
 
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==Vent and tail==
 
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The [[Cloaca|cloaca]] can be examined very simply by using a otoscope or endoscope.  Check for [[Oedema|oedema]], erythema, discharge and swellings.  Check the vent for any soiling which may be due to parasitic infection of the large intestine.  Make a faecal smear if possible.  Examine the tail for retained sloughed skin, lumps and other deformities.
 
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[[Image:Sexing_snakes.jpg|200px|thumb|right|'''Sexing snakes''' (Copyright © RVC)]]
 
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==Sexing/Probing==
 
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The snake is positioned so that the [[Vent|vent]] is easily accessible.  A smooth lubricated blunt-tipped probe is inserted caudally through the vent.  In males the probes enters the [[Hemipenes|hemipenes]] (10-12 scale rows) while in females it may enter the musk glands (2-3 scale rows).  Take care since rough use of probes can cause damage.  In females it is possible to perforate the musk gland and allow the probe to slide in as far as it would in a male snake.
 
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'''See also''' [[Snake Necropsy]].
 
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{{Learning
 
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|full text = [http://www.cabi.org/cabdirect/FullTextPDF/2009/20093018977.pdf ''' Let your fingers do the walking: how to restrain and examine snakes.''' Diaz-Figueroa, O.; The North American Veterinary Conference, Gainesville, USA, Small animal and exotics. Proceedings of the North American Veterinary Conference, Volume 22, Orlando, Florida, USA, 2008, 2008, pp 1746-1748, 1 ref.]
 
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[http://www.cabi.org/cabdirect/FullTextPDF/2009/20093118384.pdf '''Neurologic examination in reptiles - Part I: Cranial nerve examination.''' Bennett, R. A.; The North American Veterinary Conference, Gainesville, USA, Small animal and exotics. Proceedings of the North American Veterinary Conference, Orlando, Florida, USA, 17-21 January, 2009, 2009, pp 1766-1767]
 
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[http://www.cabi.org/cabdirect/FullTextPDF/2009/20093118385.pdf '''Neurologic examination in reptiles - Part II: Localizing neurologic dysfunction.''' Bennett, R. A.; The North American Veterinary Conference, Gainesville, USA, Small animal and exotics. Proceedings of the North American Veterinary Conference, Orlando, Florida, USA, 17-21 January, 2009, 2009, pp 1768-1769]
 
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}}
 
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==References==
 
==References==
 
Fowler, M.E. and Miller, R.E. (2003). Zoo and Wild Animal Medicine. Saunders, 5th Edition. pp. 84. ISBN 0-7216-9499-3  
 
Fowler, M.E. and Miller, R.E. (2003). Zoo and Wild Animal Medicine. Saunders, 5th Edition. pp. 84. ISBN 0-7216-9499-3  
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[[Category:Snake_Examination]]
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{{review}}
 
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==Webinars==
 
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<rss max="10" highlight="none">https://www.thewebinarvet.com/internal-medicine/webinars/feed</rss>
 
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[[Category:Snake Examination|C]]
 

Revision as of 14:33, 9 March 2010


 This article is still under construction.


©RVC and its licensors, Peer Zwart and Fredric Frye. All rights reserved

Introduction

The physical examination involves observation of the snake, taking measurements and a thorough methodical area by area examination. Many techniques are similar to other animals, but before examining the snake ask the owner if it is accustomed to being handled. See here for information on handling and restraint of snakes. A veterinarian who is inexperienced with reptiles may be likely to focus on the presenting signs but then can end up treating exclusively the secondary problems. Stomatitis and rectal prolapse are secondary conditions where a full examination with husbandry review, including housing and nutrition, is vital in determining the principal problem.

Observation

Snakes should have active tongues that are sampling scent particles in the atmosphere. Normal movement should be observed although allowances must be made for any chilling effect in transit since this will reduce the patient's metabolism and give a misleading impression of lethargy and lack of strength. The righting reflex should be tested since poor reactions can be a result of weakness and not necessarily neurological disease. Respiration, including rib movements and any sounds produced. Be aware of hissing noises arising from agitation that are not a result of respiratory infection.

Body condition

Weight of the snake should be taken at every examination, as should snout-vent lengths. Obese snakes have increased fat deposition on the last third of the body before the cloaca. Cachectic snakes with significant loss of muscle mass show a prominant dorsal spine and ribs, and the body shape looks more triangular in cross section.

Skin

Blisters on skin©RVC and its licensors, Peer Zwart and Fredric Frye. All rights reserved

Examine under a bright light and with a hand lens if necessary.

Examine for:

  • Ectoparasites
  • Trauma due to fighting, mating or thermal burns
  • Discoloration (previous scars, injection sites)
  • Dysecdysis - retained skin is often dry and brown while normal ecdysis occurring in a piecemeal fashion is flexible and transparent. Retained skin is a focus for infection and acts as a tourniquet on the tail tip and digits leading to ischaemic necrosis
  • Examine the scales for loss, scabs, blisters and haemorrhages, ensuring the ventral scales are inspected
  • Assess for abnormal masses, swellings or bruised areas
  • Assess skin elasticity
  • Skin folding indicates dehydration, cachexia. Assessment of dehydration in reptiles is analogous to mammals. With 5-8% dehydration there is loss of skin elasticity with a wrinkled appearance. With more severe dehydration (10-15%) the eyes are sunken and the mucous membranes become dry and sticky (consider that the oral cavity of most reptiles is relatively dry compared with mammals).

Find out more about snake skin

Find out more about snake skin diseases

Dysecdysis©RVC and its licensors, Peer Zwart and Fredric Frye. All rights reserved

Shedding

Ecdysis (shedding) generally takes place every 14 days although this is dependent on many variables such as environment, age and size of snake. Snakes shed their entire skin in one piece, including the spectacles, although large snakes greater than 3m in length may shed their skin in incomplete sections. Prior to ecdydsis, a snake will become anorectic and handling may be hazardous to the animal at this time if the underlying epidermis is damaged.

Head

Nares

The nares should be clear and free of discharge and retained shed.

Eyes

The eyes are usually considered as a barometer of general health and environmental conditions; therefore a full ophthalmologic examination should be performed in all cases.

  • Following a general assessment of the eye, a more detailed examination should be performed using a form of focal illumination and a magnification system.
  • Examination of the ocular fundus to assess the retina (fundoscopy) can be carried out using a direct or indirect ophthalmoscope.
  • Mydriasis can be attempted either through general anaesthesia or intracameral injection of neuromuscular blocking agents such as curare or d-tubocurarine. These agents can also be applied topically; however their effectiveness may be affected by the variable corneal penetration of the drugs.
  • Other diagnostic tools, such as tonometry (measurement of the intraocular pressure), stains, cytology, bacteriology, histopathology and electron microscopy, in addition to routine diagnostic tools (haemotology, biochemistry, radiology and ultrasound) can also be used to detect an ocular disease or underlying problem in snakes.
  • Retained spectacles are a concern. They should be clear with no signs of subspectacluar disease.
Ulcerative stomatitis©RVC and its licensors, Peer Zwart and Fredric Frye. All rights reserved

Oral cavity

  • The oral cavity should be opened using a soft, pliable speculum
  • Mucous membranes should be pale to pink and free of thick ropey mucous
  • Evaluate the tongue for movement
  • The glottis should be gree of discharge
  • Examine the teeth for fractures

References

Fowler, M.E. and Miller, R.E. (2003). Zoo and Wild Animal Medicine. Saunders, 5th Edition. pp. 84. ISBN 0-7216-9499-3

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