Herp Otorhinolaryngology Flashcards
Describe the ear antomy of reptiles.
What is the external ear like? What taxa have them?
What is their middle ear anatomy like? How does this vary by taxa?
Do snakes have eustachian tubes? What bone connects the mandible to the stapes?
What is unique about the turtle middle ear?
What nerve innervates hearing?
How do species without tympanums hear?
External ear:
- Depression (external auditory meatus) that collects sound waves
- Extends to tympanic membrane
- Absent in chelonians, snakes, amphisbaenians, tuataras and some lizards
- Most geckos: meatal closure muscle
- Crocodilians: muscle in dorsal skin folds (ear flaps)
Middle ear:
- Transmits and amplifies sound waves from tympanic membrane
- Chain of bony ossicles (columella) -elongated stapes, suspended in tympanic cavity
- Extends medially to oval window of the cochlea
- Snakes lack eustachian tubes - have a quadrate bone connecting mandible and stapes
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Turtles: large cavity extends caudally into blind pouch with squamosal bone
- Pharyngeal orifice of eustachian tube: buccal oral mucosa caudal to the angle of the jaw
- Crocodilians: channel system links left and right middle ears
- Lizards: tympanic cavity and pharyngeal space indistinguishable (some chameleons have thin membrane with fenestration
Inner ear
- Equilibrium and balance: semicircular canals, utricle, saccule
- Auditory perception: cochlear duct (vibrations - fluid oscillations of cochlear hair cells)
- Vestibulocochlear nerve (CN VIII)
- Species without tympanums - hearing limited to low frequency ranges 150-600 Hz (ground or water vibrations)
- Hearing not dependent on tympanic cavity size
Describe the anatomy of the nasal cavity of reptiles.
Trace the air flow through the nares into the larynx in a reptile.
How do turtles and squamates close their nares during immersion?
What is the largest cavity in the nose?
What taxa lacks concahae?
What species have nasopharyngeal ducts? Which do not?
What is the vomeronasal organ?
What species have nasal salt glands?
Nasal Cavity
- Air -> external nares -> short vestibulum nasi -> cavum nasi proprium, conchae (turbinates) -> nasopharyngeal duct -> choanae (internal nares) -> pharynx, larynx
- Select species: vomeronasal (Jacobson’s organ), nasal salt glands
- Turtles and many squamates: erectile tissue in vestibulum to close opening during water or sand submersion
- Cavum nasi proprium - largest, cavities, sensory epithelium (dorsal olfactory in chelonians)
- Chelonians lack conchae
- Tuatara lack nasopharyngeal ducts; short in lizards
- Nasopharyngeal duct is well developed in snakes, turtles and crocodilians, esp. Aquatic
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Vomeronasal (Jacobson’s) organ - ventral nasal cavity, chemoreceptors
- Absent crocodilians
- Associated with mouth in squamates
- Tuatara - in nasal septum as duct in choanae
- Turtles - similar cells arong dorsal nasal epithelium
- Gular pumping: may have olfactory rather than respiratory function
- Snakes and some lizards: rostral to choana as pair of pits on roof of mouth (tongue transfers chemical scents)
- Nasal salt glands (chuckwallas, green iguanas) - desert, herbivorous, marine lizards
- Choanae: single opening or paired structure
- Chelonians: ridges, flaps, papillae along lateral margins
- Crocodilians: basihyal valve and velum palate
Describe the anatomy of the reptiles pharynx and larynx.
What cartilages are present on the larynx? What ones are fused?
What cartilage do crocodilians lack?
What is unique about the ophidian larynx?
Pharynx/larynx
- Larynx connects the pharynx to the trachea and protects lower airways by closing
- Cartilage - thyroid, cricoid, arytenoid: thyroid and cricoid often fused
- Lies on corpus of hyoid apparatus
- Crocodilians lack epiglottis
- Snakes: muscular hyoid-type attachment allowing the upper trachea to move forward and breathing while swallowing
Aural polyps in iguanas are associated with what infection?
What are the typical clinical signs?
How are they treated?
What does the histo look like?
Tympanic protrusions
- Aural polyps in the middle ear and auropharyngeal region of the green iguana associated with cryptosporidial infections
- Protrusion of the tympanic membrane typical, anorexia, head swelling
- Histo: dense fibrous connective tissue, hyperplastic epithelium and mixed heterophils, lymphocytes and plasma cells
- Surgical removal attempted; recurrence reported
What are some of the potential causes of aural abscesses in reptiles?
What taxa is most commonly affected?
What are the typical clinical signs?
What is typically seen on histology?
How are these treated?
MARMS – 141. Aural/Tympanic Abscessation
Aural abscessation - caseous material within middle ear or tympanic cavity causing protrusion of tympanum
- Free-ranging and captive reptiles
- Most common in chelonians
- Not reported in species lacking a tympanic cavity
Causes
- Appears to be multifactorial - no known cause
- Predisposing factors - immunosuppression from poor environmental conditions (temperature, hygiene), diet (vitamin A deficiency)
- Hypovitaminosis A - hyperplasia and squamous metaplasia, including middle ear and eustachian tube
- Free ranging EBT (Terrapene carolina carolina) - organochlorine-containing pesticides that disrupt vitamin A metabolism cause similar signs
- Other studies unable to induce tympanic squamous metaplasia with correlation between organochlorine compounds and abscess formation in RES (Trachemys scripta elegans)
- Oropharynx and middle ear connected by eustachian tube -> pathway for ascending infections
- No consistent pathogens, most opportunistic commensals (aerobic gram negatives)
- Hematogenous spread and trauma less likely positive
Clinical signs
- Tympanic swelling(s) - semi firm to firm, unilateral or bilateral
- swelling of tympanic membrane rather than rupture
- Caseous debris (no lysosomes in leukocytes)
- Caseous debris can be seen in pharynx, through eustachian openings
- Diagnosis based on visual assessment/PE
- Vestibular signs not typical, head tilt can occur
Histology
- Mild: squamous metaplasia and hyperplasia
- Severe: inflammation, osteolysis
Diagnostics
- FNA cytology to differentiate from neoplasia
- Hematology and chemistry to evaluate for systemic disease
- Radiography/CT - severity, management
Treatments
- Surgical management
- Daily lavage
- Healed with second intention
- Antibiotics not usually indicated
- No evidence confirming Vitamin A supplementation alone adds relief
- Bigger risk if given parenterally
Prognosis is good with complete removal and correction of husbandry/nutrition
Recurrence: inadequate debridement, failure to address underlying factors
Describe mycoplasma rhinitis in chelonians.
What species have experienced population declines as a result?
What is the course of infection typically like?
How can you tell acute from chronic infections?
Which Mycoplasma is the most severe?
What are the lesions found on histopath?
What coinfections may occur?
Mycoplasmosis
- Disease in other animals typically associated with chronic lower respiratory tract disease (pneumonia, pleuropneumonia)
-
Chelonians: upper respiratory tract disease (URTD)
- nasal discharge/rhinitis, conjunctivitis, ocular discharge, palpebral edema (not pneumonia)
- May be associated with population declines of the desert tortoise (Gopherus agassizii) and gopher tortoise (Gopherus polyphemus)
- Clinical signs develop as early as 2 weeks post infection
- Clinical signs intensify and abate cyclically -> grooves ventrally from nares, eroded nares and depigmentation can develop
- Subclinical infections reported
- Decreased activity, irregular basking and burrowing behaviors, reduced foraging
- Stress from environmental change or poor husbandry can increase morbidity/mortality
- Host immune response contributes to disease severity
- Confirmed URTD species (chelonians): Mycoplasma agassizii, M. testudineum
- M. testudineum more focal and less severe pathology than M. agassizii
- Coinfections with herpesvirus and ranavirus reported
- Pathology
- M. agassizii attaches to ciliated mucosa epithelium to disrupt normal tissue architecture and function
- Severe infections: nasal cavities can be completely obstructed with thick caseous discharge, nasal cavity erosion, reduced coelomic fat, thymus atrophy, hepatic hemosiderosis, lymphocytic inflammation in splenic sinusoids
- Histology: multifocal to focally extensive subepithelial lymphoid aggregates, a mixed inflammatory cell infiltrate consisting of heterophils, lymphocytes, plasma cells and macrophages, basal cell hyperplasia, mucous and olfactory epithelial metaplasia, and erosion of the ciliated epithelium
- Gopher tortoises with URTD were more likely to have gram-negative bacteria isolated from nasal cavity - increased susceptibility to secondary infections
Describe the effects of mycoplasma in species other than chelonians.
What mycoplasma species affect crocodilians? What are the typical clinical signs and lesions?
How are snakes and lizards affected?
Mycoplasma in Other Reptiles
- Crocodilians: fulminant lethal sepsis (alligators), synovitis/arthritis
- Snakes: has been implicated in pneumonia
- Chronic morbidity, mortality associated with initial outbreaks or with stress
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M. alligatoris and M. crocodylii cause arthritis and pneumonia in crocodilians
- M. alligatoris associated with multiorgan sepsis and mortality in alligators and caimans
- Pathology of naturally infected alligators: multifocal abscesses of the coccygeal and thoracic vertebrae, degradation of spinal cord white matter, fibrosis, vertebral osteomalacia and epaxial myofiber degeneration; mixed inflammatory infiltrate in lungs/airways with edematous connective tissue, hyperplastic bronchial epithelial lining; pericardial fluid, fibrinous adhesions of parietal and visceral pericardia
- M. iguana considered to be pathogenic, but etiology not confirmed
- Reports of Mycoplasma sp in boids and pythons presenting for tracheitis and pneumonia, clinical significance not determined
How is mycplasma transmitted?
What diagnostics are recommended?
What medium is needed to grow mycoplasma?
What samples should be collected?
What is the first line of treatment?
What is the prognosis for mycoplasmosis?
What control measures should be implemented?
Transmission: direct contact, nasal discharge; vertical transmission at low rates likely; does not persist long in environment outside of host (however may persist in high density captive environment)
Diagnostics
- Culture; mycoplasma specific medium (SP4) needed, special labs
- Tortoise species cultured at 30 deg C, grow slowly (6 wks for isolation)
- Crocodilian species grow rapidly (24 hours), but different optimal growth temperatures
- PCR: early stages or currently shedding, shipping with mycoplasma media
- ELISA: validated for tortoises, may not detect tortoises in earliest stages of infection, but more likely to detect subclinical, intermittent shedders, or chronic infections; serum or plasma can be used
- Sampling for culture/PCR: nasal swabs, nasal flushes (colonizes ventro lateral depression, oral swabs close to choanal opening can be used for PCR
- Western blot: confirmatory test (M. crocodylii)
Treatment
- Differentiating between clearance and subclinical infection difficult (long term oral clarithromycin therapy for 3 months failed to clear subclinical infection from all but one animal)
- Tortoises and snakes: isolated, supportive care, antimicrobials
- Mycoplasma does not have a cell wall
- Antibiotics: tetracyclines (recommended as first line), fluoroquinolones, lincosamides, macrolides, some aminoglycosides
- Topical antibiotic and steroid combos with systemic antibiotics
- Nasal flushes, topicals (ophthalmic)
Prognosis
- Acute death rare except in alligators
- Pneumonia in snakes can have poor outcomes if untreated
- Mortality common in chelonian hatchlings in initial transmission
- Most tortoises develop chronic disease with intermittent signs
Control
- Disinfection: 3-5% bleach
- Isolate, separate eggs and hatchlings
- Separate clinical ill animals for treatment
- Introduction of rehabbed tortoises into naive populations have resulted in mortality events - release where found (if releasing)
Describe rhinitis in reptiles that is not associated with mycoplasma infection.
What are some potential causes of epistaxis?
What are some infectious differentials to consider for rhinitis?
What bacterial infections cause obstructive rhinitis in sea turtle juveniles?
What are some noninfectious causes of rhinitis in reptiles?
What are some causes of rostral abrasions?
Non-mycoplasma rhinitis
- Nasal discharge: rhinitis, stomatitis, pneumonia; distinguish from gastric reflux
- Epistaxis uncommon, almost always abnormal
- Long-nosed snakes and dwarf boids can squirt blood from their nostrils as a defense mechanism (autohemorrhage)
- Metastatic mineralization can cause bleeds in green iguanas
- Iatrogenic hypervitaminosis D, hypercalcemia
- Infectious causes of rhinitis: herpesviruses, ranaviruses, adenoviruses, reoviruses, intranuclear coccidiosis,Pasteurella testudinis, iridovirus, chlamydiosis
- Fungal infection or chronic respiratory tract disease is another differential from nasal depigmentation
- Obstructive rhinitis - usually with ulcerative stomatitis and/or bronchopneumonia
- High mortality rates in hatchling and juvenile green turtles (C. mydas) and loggerheads.
- Vibrio alginolyticus, Aeromonas hydrophila, Flavobacterium
- Rhinoliths rare
- Dysecdysis can occur within nares - ususally resolves on its own
- CT useful in evaluating nasal cavity
- Noninfectious: foreign bodies, congenital (oronasal fistula), inhaled irritants, rostral trauma
- Differentiate from normal salt discharge in reptiles with salt glands
- Choana - foreign bodies (plastic straws and forks in sea turtles, fish hooks), digesta, inflammation, petechiae, icteric changes
- Overrepresented species for rostral trauma in human care:
- bearded dragons, pater dragons, terrestrial snakes
- Mature male snakes housed near females
- Overcrowding
- Inappropriate cage design
- Feeding live prey
Describe the causes of laryngitis and pharyngitis in herps.
What crocodilian species is commonly affected by pharyngitis, layngitis, and conjunctivitis? What pathogens have been detected? What demographic is affected? What is the prognosis?
What is the cause of necrotizing pharyngitis, tracheitis, pneumoni, and esophagitis in gopher tortoises? What are the typical lesions?
A similar syndrome in ball pythons is caused by what pathogen?
What are the helminths that infest the pharynx of frogs?
Laryngitis and Pharyngitis
- Pharyngitis/laryngitis/conjunctivitis syndrome
- Australian farmed saltwater crocodiles
- Primarily hatchlings and juveniles
- Severe lesions - mixed gram-negative and gram-positive bacteria, occasional hyphae
- PCR detected a 55% prevalence of Chlamydia sp (81% of these also harbored herpesvirus infection)
- Poor treatment trial responses
- High mortality rates
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Multifocal necrotizing pharyngitis with concurrent tracheitis, pneumonia and esophagitis
- Gopher tortoise
- Intracytoplasmic viral particles resembling Iridovirus
- Similar respiratory syndrome (pharyngitis, sinusitis, stomatitis, tracheitis, and a proliferative interstitial pneumonia with caseous material in the choana) - ball pythons due to Nidovius
- Rhabdias sp. Nematode lungworms common in anurans
- Trematodes in oropharynx of anurans - clinical significance undetermined
- Myiasis in amphibians:
- Bufolucilia - nasal passages, often fatal
- Pharyngeal myiasis - sarcophagid flesh fly larva (Diptera)
- Larval ascarids (Hexametra sp) - severe purulent abscess forming pharyngitis in green striped tree dragon concurrently with viruses
What are some causes of pharyngeal and submandibular edema in reptiles?
Cervical aneurysms are commonly reported in what species? How do they typically present?
A laryngeal paralysis type syndrome is reported in what species of seaturtle?
What neoplasma may affect the upper respiratory tract?
Pharyngeal and submandibular edema and cellulitis
- Swelling of mandible can interfere with normal breathing and swallowing, may cause dysphagia
- Pharyngeal edema associated with renal disease in green iguanas (hypoproteinemia)
- Ranavirus infection in green pythons - pharyngeal submucosal edema, nasal mucosa ulceration, hepatic necrosis, severe necrotizing inflammation reported
- Accessory lung lobe of some chameleons - cervical swelling if it fills with fluid, parasites or inflammatory exudates
Cervical aneurysm
- Adult bearded dragons
- Also reported in green iguana and burmese pythons
- Dissecting aneurysms from internal carotid or aorta
- Presents with large unilateral fluctuant to firm swelling in dorsolateral neck or dorsal to temporal muscles
- Doesn’t typically affect behavior
- Aspiration - whole blood (may coagulate), immediate refill
- One successful surgical case reported
- Etiology unknown - trauma, hypertension, genetic predisposition
Laryngeal paralysis-like condition in loggerhead
- Stertorous upper airway sounds with partial airway obstruction
- Abnormalities of the abductor arytenoideae or dilator laryngis muscle
- Histology revealed unilateral myofiber atrophy
- Etiology unknown
Neoplasia
- Primary neoplasms not common in herps
- Most frequent in snakes
- Lymphoma (secondary infection) in cranial cervical area of green iguana (remission with radiation and chemotherapy
- Squamous cell carcinoma reported in a Madagascar ground boa’s caudoventral pharyngeal region
- Thyroid adenoma in a green iguana with ventral cervical mass
- One report of olfactory neuroblastoma involving the Jacobson’s organ of a blue-tongued skink
- Growths from adjacent organs can impede ENT - fibropapilomas
What are some indications for aural surgery in reptiles?
Describe your surgical and management approach to an aural abscess.
MARMS – 92. Ear Surgery
Surgical intervention is not common
- Polyps, neoplasia, abscesses, protruding/obstructive growths
- Diagnostics and surgical planning depend on condition - imaging, FNA, radio/laser/cryosurgery helpful in some cases
Aural abscesses
- Authors (Divers, Kischinovsky) recommend surgical plane of anesthesia, intubation and packing the oral cavity with moistened gauze to prevent aspiration
- If not intubated, ensure head is in down position during lavage (AK)
- Sedation with opioid analgesics as well as lidocaine block typically adequate for for free-ranging wildlife: allows for shorter monitoring period, good for patients when less certain of stability (AK)
- Aseptic preparation with povidone-iodine; avoid chlorhexidine and alcohol (proximity to eyes)
- Most cases: full thickness incision through tympanum along ventral border from 9 o’clock to the 3 o’clock positions
- Okay to remove entire tympanic membrane if needed
- Remove caseous debris with small ear loops, should get plug (funnel shape from eustachian tube)
- Avoid damaging columella
- Collect samples for histo, culture/sensitivity, acid-fast stains or PCR (Chryptosporidium) if indicated by case or abnormal tissue
- Inspect caudomedial aspects of tympanic cavity
- Ensure patency of eustachian tube:
- larger tortoises (red rubber, careful use of cotton tipped applicator)
- Lavage liberally with sterile saline
- Severe case example: tympanic membrane was marsupialized to delay healing until infection resolved and red rubber was sutured to facilitate flushing (uncooperative patient)
- Flush q24h until wound closed and apply topical treatment (triple antibiotic ointment)
- 1-3 days of analgesics
- Aquatic species: drydock for 24 hours, then maintained in shallow water below surgical site for 10 to 14 days (recommended by authors)
- Additional supportive care may be indicated, but reptiles typically recover quickly. TRT’s EBTs tend to eat pretty quickly after surgery (AK)
- Recheck: one week; 6-8 wks
What are some indications for rhinotomy in reptiles?
What are some complicatios with rhinotomy? How can these be mitigated?
How are foreign bodies removed?
MARMS – 93. Rhinarium (nostrils, nasal passages, choana)
Few indications for rhinotomy
- Nostrils common site of trauma
- Abscesses of maxilla may involve rhinarium
- Osteomyelitis
Trauma
- Captive reptiles and amphibians prone to self trauma from striking at enclosure (traumatic injuries very common in free ranging chelonians as well)
- Damage to rostral area -> open mouth breathing -> drying of oral mucosa -> secondary oral and/or respiratory disease
- Imaging (CT) may be helpful in cases that develop osteomyelitis, stomatitis or fractures for surgical planning
- Aggressive surgical debridement of infected tissue and bone fragments indicated
- Deep samples for cytology and bacterial/fungal cultures, or infectious disease PCR (chlamydia, mycoplasma, ranavirus, herpesvirus, nidovirus) if indicated
- Area is highly vascularized - hemorrhage, laryngeal obstruction -> dyspnea
- Radiosurgery or laser modalities can be helpful
- Avoid damaging nares
- Caution with flushing choana - aspiration
- Husbandry changes should also be addressed
- Corrective surgery difficult, bandaging not usually possible
- Flush q12-24h and topical antiseptics (dilute chlorhexidine or betadine); topical ointments depending on location
- Nutritional support often indicated
- Surgical anesthesia recommended, oral speculums helpful
- Endoscopy helpful, dental/ophthalmic surgical equipment helpful
Foreign bodies, rhinoliths
- Plastic straws and forks in sea turtles (removed with pliers, cleaned with betadine)
- Fish hooks
- Endoscopy recommended
- Rhinoliths not common -> rhinoscopy would aid in investigation/removal when possible
