Equine dentistry Flashcards
what type of teeth do horses have?
hypsodont (long crowned)
what does hypsodont mean?
long crowned
how fast do horses teeth erupt?
2mm/year
what is the deciduous dental formula for equids?
I 3/3 C 0/0 PM 3/3 (24)
what is the permanent dental formula of equids?
I 3/3 C 1/1 (0/0) PM 3/3 (4/4) M 3/3 (24)
what number is the upper right quadrant of the triadan system?
1
what number is the upper left quadrant of the triadan system?
2
what number is the lower left quadrant of the triadan system?
3
what number is the lower right quadrant of the triadan system?
4
how is the deciduous teeth of equids numbered using the triadan system?
add 4 to quadrant number (upper right =5, upper left =6…)
when do the deciduous incisors of horses erupt?
(01) central - 1 week
(02) middle - 6 weeks
(03) corner - 6 months
(6 days, 6 weeks, 6 months)
when do the permanent incisors of horses erupt?
central - 2.5 years
middle - 3.5 years
corner - 4.5 years
when do canine teeth of horses erupt?
5 years (not all have them)
when do wolf teeth erupt?
1 year
when do deciduous pre-molars erupt?
present at birth
when do the permanent cheek teeth of horses erupt?
1-4 years (06 - 2.5 years 07 - 3.5 years 08 - 4 years 09 - 1 year 10 - 2 years 11 - 3.5 years)
how many infundibulae do maxillary cheek teeth have?
2
what shape are maxillary cheek teeth?
square (wide)
how many infundibulae do mandibular cheek teeth have?
none
what shape are mandibular cheek teeth?
rectangular (narrow)
what are pulp horns?
areas of pigmented secondary dentine on the occlusal surface of teeth (cheek teeth have at least 5)
what sinuses are close to the cheek teeth?
rostral maxillary
caudal maxillary
what is anisognathia in relation to horses??
maxillary cheek teeth wider than mandibular
what are two normal anatomical variations of the mouth?
curvature of maxilla
curve of spee
when watching a horse with suspected dental disease eat, what is looked at?
normal grinding sounds
chewing with both sides
takes longer chewing
quidding
what is assessed when looking at incisors?
masses/trauma
occlusion from side/front
count teeth
where should be palpated on an examination of cheek teeth?
occlusal surface edges of teeth interdental space buccal mucosa tongue adjacent to teeth
what are category one dentistry procedures?
examination
using manual rasps
what is parrot mouth also known as?
overbite
what is parrot mouth?
overly long maxilla compared to mandible (brachygnathism)
what can overbite cause?
ulceration behind upper incisors
overgrowth of teeth
what is prognathism?
overgrowth of mandible compared to the maxilla
what is campylorrhinus lateralis also known as?
wry nose
what is wry nose?
deviation of entire maxilla (incisive region, nasal septum, bones)
what does slant mouth indicate?
horse is eating predominantly on one side
where are retained deciduous incisors found in relation to permanent teeth?
rostrally
when incisors are fractured, what determines if they can be repaired or not?
if the pulp cavity is effected
what is equine odontoclastic tooth resorption and hypercementosis?
swelling/draining tracts over multiple mandibular/maxillary incisors
what is done to treat equine odontoclastic tooth resorption and hypercementosis?
extract loose incisors (may have to remove all)
what is the most common oral neoplasm of dental origin?
ameloblastoma
what is done to treat ameloblastomas?
surgical extraction
what are common oral neoplasias of soft tissue origin?
squamous cell carcinomas
sarcoid
epulis
fibroma
what is the most common problem seen with canines?
calculus build up (remove)
what are indications for wolf tooth removal?
bitting problems
ulceration
blindly erupting (pain)
what are retained caps?
remnants of deciduous teeth (normally shed during eruption of permanent teeth)
how are retained caps usually attached?
in one place to gingiva (site of pain)
what causes cheek teeth displacements?
overcrowding during eruption
what happens if the cheek teeth develop too far apart?
diastemata forms
food accumulates
fermentation (gingivitis)
periodontal disease
where do supernumerary cheek teeth usually develop?
caudal aspect of cheek teeth
what aspect of the cheek teeth does enamel overgrowth effect?
maxillary - buccal
mandibular - lingual
enamel overgrowth is more pronounced in horses fed what?
more concentrates and less forage
what is wavemouth?
undulation to occlusal surface
what is stepmouth?
focal overgrowth of single tooth (reduce in stages) - usually due to missing opposing tooth
what is shearmouth?
increase occlusal angle to entire cheek tooth row
what is shearmouth usually secondary to?
diastemata or dental fracture
how is shearmouth managed?
treat primary problem
gradual reduction
what is bit seating?
rostral profiling of cheek teeth (contraindicated)
what is smooth mouth?
cheek teeth enamel worn away, dentine and cementum become smooth (dietary management)
what are dental caries?
food material becomes trapped in pits in peripheral cementum
what happens when food gets trapped in pits that lead to dental caries?
fermentation
drop in pH
demineralisation
larger pits in cementum form
how should diastemata without periodontal disease be treated?
cleaned out completely and packed with impression material
how should diastemata with periodontal disease be treated?
widen with a mechanised burr and pack with impression material (feed short fibre)
what are the three types of cheek teeth fractures?
buccal slab
midline sagittal
occlusal fissure
what are the clinical signs of apical infection?
facial swelling
unilateral nasal discharge
mandibular swelling
what can cause apical infections?
anachoresis (blood-borne infection)
fracture
periodontal spread
pulpar exposure
what are the ways of removing a cheek tooth?
oral extraction
modified transbuccal extraction
lateral buccotomy
repulsion
what is the first step of oral extraction of cheek teeth?
interdental spreading (increase space infant/behind the tooth)
what is the second step in oral extraction of cheek teeth?
application of molar forceps and wiggle
when is modified transbuccal extraction used?
when the crown is fractured
what are the function of the upper airway?
air flow filtering/protection olfaction phonation swallowing thermoregulation
what is the respiratory rate of a horse?
15bpm
what is the tidal volume of a horse?
5L
what is the minute ventilation of a horse?
75L
the breathing pattern of a horse is coupled with their gait, how?
inspiration - back feet on the ground
expiration - front feet on the ground
(canter)
what does narrowing of the upper airway lead to?
increased negative pressure on inspiration - collapse of structures (pharynx/larynx)
where does unilateral nasal discharge come from?
sinus or nasal passage (rostral to nasal septum)
where does bilateral nasal discharge come from?
larynx, pharynx, lower respiratory tract (caudal to nasal septum)
what is the rebreathing test used on horses?
place bag over nose to increase respiratory rate/force, then take away and examine
what should happen in a healthy horse when the bag is removed during the rebreathing exam?
1 or 2 deep breaths with no coughing
what are normal sounds heard on exercise?
snorting
high blowing
sheath noise
thick wind
what are the main methods of diagnostic imaging used for the head?
endoscopy (resting/exercise)
radiography
sinoscopy
CT
what are the standard radiographic views to assess the horses head?
latero-lateral
lateral oblique
dorso-ventral
what is latero-lateral radiographic views of the head good for assessing?
paranasal sinuses, guttural pouch, pharynx
what is the lateral oblique radiographic view used for?
assess periodontal regions of cheek teeth
what is the dorso-ventral radiographic view of the head used for?
paranasal sinus
nasal septum
teeth
(compare left/right)
what are the indications for CT scanning of horses head?
dental disease
masses of paranasal sinus
trauma
what can cause facial nerve paresis/paralysis?
recumbency with pressure on nerve
iatrogenic
what are the clinical signs of facial nerve paresis/paralysis?
facial swelling/asymmetry
reduced airflow and stertor
why is minimal debridement need for lacerations of the nares?
good blood supply (preserves tissues)
how many suture layers should be used to close a laceration of the nares?
2-3
what is nasal atheroma?
cyst within the nasal diverticulum
what is the major clinical sign of nasal atheroma?
non-painful swelling at nasoincisive notch
what is done to treat nasal atheroma?
surgical removal
what are the clinical signs of alar fold collapse?
flaccid alar folds
respiratory noise
exercise intolerance
what are the three meati formed from the turbinates?
dorsal
middle
ventral
why is the sinus drainage angle an important anatomical feature?
(narrow passage from paranasal sinus to nasal passage)
cannot access using endoscopy
what is the significance of ethmoturbinate 2?
when passing a gastric tube must push down to avoid damaging
how can iatrogenic trauma to the nasal passage be prevented when passing a tube?
pass ventral to middle meatus
smooth tube
lubricate
(do not force!!)
what is a progressive ethmoid haematoma (PEH)?
encapsulated non-neoplastic mass
where can progressive ethmoid haematomas grow into?
nasal passage and paranasal sinus
what are the two main clinical signs of progressive ethmoid haematoma?
epistaxis facial swelling (sinuses)
how do progressive ethmoid haematomas appear on endoscopy?
yellow/green mass
what can be done to treat progressive ethmoid haematoma?
intralesional formalin (care with cribriform plate) laser excision (sinus flap surgery)
what can fungal rhinitis commonly occur secondary to?
bacterial sinusitis
what are the main clinical signs of fungal rhinitis?
purulent/haemorrhagic discharge
malodorous smell
nasal stertor
what can be done to treat fungal rhinitis?
remove plaques/necrotic bone topical antifungals (enilconazole)
how many pairs of paranasal sinuses are there?
7
what are the two functional groups of paranasal sinuses?
rostral
caudal
what paranasal sinuses are included in the rostral group?
rostral maxillary
ventral conchal
what paranasal sinuses are included in the caudal group?
caudal maxillary frontal dorsal conchal sphenopalatine ethmoid
what structures are the paranasal sinuses near?
brain
teeth
what separates the rostral and caudal paranasal sinus groups?
oblique bony septum
why is paranasal sinus drainage often inhibited in horses?
drain when head is down eating grass (modified diet causes issues)
what are the most common diseases effecting paranasal sinuses?
primary sinusitis
secondary sinusitis
what are the two most common presenting signs of paranasal sinus disease?
nasal discharge
facial swelling
what can cause secondary sinusitis?
dental disease
sinus cyst
progressive ethmoid haematoma
neoplasm
what is done to treat primary sinusitis?
culture sensitivity testing then one course of antibiotics
NSAIDs
feed from ground (drainage)
turn out and reduce dust
what is the most common cause of secondary sinusitis?
dental disease
what age animal are paranasal sinus cysts most common in?
young horses
what is done to treat paranasal sinus cysts?
surgical remove by sinus flap
what are common neoplasm of the paranasal sinuses?
SCC
adenocarcinoma
myxoma
fibro-osseous tumour
what are potential complications of sinus surgery?
haemorrhage
infection
poor cosmetics
reoccurring sinusitis
what is suturitis?
inflammation in the suture line (where bones join)
what separates the nasopharynx and oropharynx?
soft palate
where is the larynx found?
in the soft palate
why is pharyngeal collapse during exercise common?
pharynx lacks rigid support (bones/cartilage)
what are the functions of the pharynx?
passage of air and ingesta
what happens in the pharynx to protect the airway during swallowing?
arytenoid closure
vocal cord closure
epiglottis retroversion
what are the functions of the larynx?
breathing
protect lower airway
vocalisation
what cartilage rings make up the larynx?
cricoid
thyroid
epiglottic
arytenoid (paired)
what are the three process of the arytenoid cartilage?
muscular
corniculate
vocal
what is the the muscular process of the arytenoid cartilage for?
cricoarytenoideus dorsalis (CAD) muscle attachment
what is the the vocal process of the arytenoid cartilage for?
vocal cords attach
what process of the arytenoid cartilage can be seen on endoscopy?
corniculate
what are the two ways the larynx can move?
abduction (breathing)
adduction (swallowing)
what muscle abducts the larynx?
cricoarytenoideus dorsalis (CAD)
what muscle adducts the larynx?
cricoarytenoideus lateralis
what nerve innervates the muscles that abduct and adduct the larynx?
recurrent laryngeal nerve
what are the key clinical signs of a horse with laryngeal/pharyngeal disease?
respiratory noise
exercise intolerance
poor performance
what are the two main modes of imaging used to asses the larynx/pharynx?
endoscopy
ultrasound
what is DDSP?
dorsal displacement of the soft palate
when is intermittent DDSP seen?
during intense exercise (expiratory obstruction)
how is intermittent DDSP correct by the horse?
swallowing returns it to normal
what can persistent DDSP be secondary to?
epiglottic entrapment
sub epiglottic ulcer
sub epiglottic cyst
what can cause intermittent DDSP?
neuromuscular dysfunction
lower airway disease
structural abnormalities
how can lower airway disease cause intermittent DDSP?
increases negative pressure
how can the majority of intermittent DDSP cases be treated?
conservative - maturity, get horse fit, change tack, tongue tie, treat inflammation
what surgeries can be used to treat DDSP?
tie forward
palatoplasty
how is a tie forward surgery for DDSP treatment carried out?
suture from basihyoid bone to thyroid cartilage (larynx postponed more rostrally/dorsally)
how does palatoplasty work to treat DDSP?
thermal/laser cautery causing a stiffened soft palate
what is pharyngeal lymphoid hyperplasia?
enlargement of lymphoid follicles of the walls/roof of nasopharynx (incidental)
what can nasopharyngeal collapse cause in neonates?
dysphagia and respiratory distress
how is nasopharyngeal collapse treated in neonates?
self-resolves
which side does recurrent laryngeal neuropathy usually effect?
left unilateral (paresis/paralysis)
what is the pathophysiology that causes recurrent laryngeal paralysis?
loss of myelinated fibres of recurrent laryngeal nerve leading to atrophy laryngeal muscles
what are the surgical options for treatment of recurrent laryngeal neuropathy?
prosthetic laryngoplasty (tie back)
ventriclo-cordectomy (hobday)
laryngeal re-innervation
arytenoidectomy
how is prosthetic laryngoplasty (tie-back) carried out?
suture placed from cricoid cartilage to muscular process of arytenoid (mimics CAD)
what is the disadvantage of prosthetic laryngoplasty (tie-back)?
permanent abduction of left arytenoid (may struggle to protect airway when swallowing)
what are potential complications of prosthetic laryngoplasty (tie-back)?
coughing
seroma formation
infection
dysphagia
how does a vocalcordectomy work to treat recurrent laryngeal neuropathy?
remove vocal cord to remove collapsing tissue into the airway
how is laryngeal re-innervation carried out?
implant C1/C2 nerves onto effected CAD
what can cause bilateral laryngeal paralysis?
hepatic disease
toxins
post anaesthetic complications
what is laryngeal dysplasia?
congenital abnormality in the development of the laryngeal cartilage (4BAD)
what dysfunction does laryngeal dysplasia lead to?
limited abduction of right arytenoid cartilage
when is a noise heard with vocal cord collapse?
inspiration (whistle)
what is the only way of detecting vocal cord collapse?
overground scope (only happens at exercise)
when is noise heard with medial deviation of the aryepiglottic folds?
inspiration
what is done to treat medial deviation of the aryepiglottic folds?
laser removal of aryepiglottic folds
what is used to treat sub epiglottic cysts?
laser extraction
snare excision
what is arytenoid chondritis?
infection/inflammation of arytenoid cartilage
what are guttural pouches?
air filled out-pouchings of the auditory tubes connecting the middle ear to the nasopharynx
what sits close to the guttural pouches dorsally?
skull/1st cervical vertebrae
tympanic bulla
auditory meatus
what sits close to the guttural pouches ventrally?
nasopharynx
retropharyngeal lymph nodes
what sits close to the guttural pouches laterally?
parotid and mandibular salivary glands
what significance does the stylohyoid bone have to the guttural pouches?
separates them into medial and lateral (medial larger)
what arteries pass through the guttural pouch?
internal and external carotid arteries
what vessels supply the brain makes surgery of the guttural pouch more complex?
circle of willis (base of the brain)
what are the most important clinical signs of guttural pouch disease?
epistaxis
dysphagia
nasal discharge
why do horses with guttural pouch disease get dysphagia?
swallowing nerves pass through guttural pouch
what is the best way to image the guttural pouch?
endoscopy
what is guttural pouch mycosis?
fungal infection of the guttural pouch (artery erosion)
what are the clinical signs of guttural pouch mycosis?
nasal discharge epistaxis nerve dysfunction (horners, dysphagia, laryngeal paralysis)
what are the differential diagnoses for epistaxis?
guttural pouch - mycosis
paranasal sinus - trauma, progressive ethmoid haematoma
nasal passage - trauma
lower respiratory tract - exercise induced pulmonary haemorrhage
where should endoscopy of suspected guttural pouch mycosis be done?
surgical facility (high risk of haemorrhage)
how must arteries be occluded for guttural pouch mycosis surgery?
on cardiac and cerebral side (internal/external carotid depending on what’s effected)
when can guttural pouch mycosis be managed medically?
if there is no plaques overlying the arteries (fungal flush)
what causes rupture of rectus capitis and longus capitis muscles?
head trauma (rearing and falling)
what is the clinical sign of rupture of rectus capitis and longus capitis muscles?
blood emanating form the guttural pouch (they haemorrhage into the guttural pouch)
what is guttural pouch empyema?
purulent material in the guttural pouches (chondroids is when it hardens)
what are the clinical signs of guttural pouch empyema?
purulent nasal discharge
lymph node enlargement
dysphagia
what are chondroids?
inspissated purulent material (chronic infection)
what age animals does guttural pouch tympani occur in?
less than 1 year old
what is guttural pouch tympani?
air gets trapped
what are the clinical signs of guttural pouch tympani?
retropharyngeal swelling
respiratory stridor
dysphagia
what is usually done to treat guttural pouch tympani?
catheters placed until animal matures and valves start operating normally
what is temporohyoid osteoarthropathy?
progressive arthritic disease of stylohyoid
what are the main clinical signs of otitis media?
headshaking
vestibular
what is otitis media?
infection of the middle ear
what is the most common neoplasm of the guttural pouch?
melanoma in grey horses
what is the location for a tracheostomy?
midline on the upper third of the neck
what incisions are made for a tracheostomy?
vertical through the skin
horizontal between the rings