Horses 1 Flashcards
what are some clinical signs of teeth related conditions in horses
- Trouble eating
- Quidding (food falling out of mouth)
- Grain in manure
- Colic/Choke
- Slobbering
- Mouthing
- Not eating
- Weight loss
- Fighting bridle
- Throwing head
- Bad head carriage
- Off balance (lame)
- Facial swelling
- Lumps under jaw
- Draining fistula
- Bad breath
- Nasal discharge
Dental examinations how often recommended at what age and why
- Recommended at least twice yearly
- Even more frequently in some younger and older horses
○ Younger -> caps (deciduous premolars) that when growing out could get food stuck in between -> born with 3 cheek teeth
§ Cups shed at following ages
□ 2.5 years - P2
□ 3 years - P3
□ 4 years - P4
§ Discomfort generally in 3 and 4 year old
○ Older -> malocclusion due to abnormal wear or loss of teeth
Horse dentition what are the 5 main types of teeth and how many/function
1) Incisors -> 3 incisors
- From midline outwards called central, intermediate and corner incisors
2) Canines -> most males (fighting teeth) have and most females don’t (20% will get)
- Brachydont -> don’t continually erupt
3) Wolf teeth -> vestibule pre-molar 1, not always present, could be just one side
- Frequently removed as being blamed for interfering with bit when horse is ridden
4) Premolars -> 3 (not including wolf teeth)
5) Molars -> 3 - grinding food
horse how many possible permanent teeth, what type of teeth and what do they have
36-44
- ALL permanent teeth are hypsodont (high crowned teeth) in horses with peripheral crown cementum (i.e. cementum on the outside of the crown of the tooth over the enamel) -> continue eruption
- They have a reserve crown, which accommodates continual wear.
○ As this reserve crown is within the alveolus, cementum covers the surface of the enamel to allow for attachment of the periodontal ligament.
what leads to the discolouration of horses teeth and what occurs with the development of the cheek teeth
- The discolouration of horse teeth is due to food pigments staining the dead cementum of the crown.
○ This is not calculus as seen on the teeth of small animals.
○ The tooth of the horse is composed of enamel, cementum and dentine as with other species.
The development of the cheek teeth
○ During development, deep enamel infolding occurs forming enamel lakes (infundibulae) - filled with cementum
What is the triadian system in horse and number important teeth
100 - upper right 200 - upper left 300 - lower left 400 - lower right 101-103 = incisors 104 = canine 105 = wolf tooth 106-108 = PM 109-111 = M Deciduous teeth -> 500,600,700,800
in terms of aging foals up with 2 years old based on teeth what is involved
6 days: central incisors present
6 weeks: central and intermediate incisors present
6 months: all incisors present (corner incisors erupt)
12 months: dental star present in central incisors, corner incisors not in wear
18 months: corners in wear
24 months: dental star in all lower incisors, M2 present
in terms of permanent dentition when central incisors, intermediates and corners erupt therefore when complete dentition
2.5 years: permanent central incisors erupted
3 years: centrals in wear
3.5 years: intermediates erupted
4 years: centrals and intermediates in wear
4.5 years: corners erupted
5 years: all incisors in wear (dentition complete at this age)
what occurs in terms of dentition to 6,7 and 8 year old
6 years: cups disappear from centrals, oval shaped occlusal surface
7 years: small hook present on distal aspect of the upper corners. Cups present in corners only.
8 years: incisors oval, cups gone, dental star present in centrals - VERY HARD TO DEERMINE AFTER THIS
what occurs in terms of dentition at 10 years, 15 years, 20 and 20+ years and what is important to remember
10 years: Galvayne’s groove at gum margin of corners, centrals and intermediates round, corners oval
15 years: Galvayne’s groove halfway down corner incisor, centrals triangular, corners round. Bite plane starts to become more angled.
○ Enamel ring goes lingually - disappears at 16 years in centre incisors
20 years: Galvayne’s groove extends full length of corner incisor. Lower incisors may be worn almost all the way to the gum - enamel ring
20+ years: Galvayne’s groove moves down the corner until it grows out.
In terms of oral examination what are some important equipment
WEAR GLOVES - Full-mouth gag/speculum ○ Haussman/McPherson - Dental Halter - Flush mouth - Light source - torch - Consider Sedation/Local - Anaesthesia
How to use a horse gag during dentals
Placed with ratchets facing DOWN
Plates at the front sit between the incisors
Strap behind ears firmly to prevent gag slippage
Gag opened gradually by one or two ratchets at each side
Mouth examined by inserting hand through the side of the mouth and feeling the teeth
AVOID placing hand between the cheek teeth rather insert along buccal or lingual sides
visual and manual examination of the mouth during dental examination what are looking at
- Soft tissue ○ Ulcers ○ Foreign bodies ○ Tongue - Teeth/Gums ○ Visualize ○ Palpate (v. sensitive) § Determine mobility § Gingival margins § Periodontal pockets -clear -> probe and mirrors used to detect
In terms of incisors what common pathology occur here
- Common site of trauma - fracture avulsions
- Malocclusions - generally not a problem
○ May indicate molars problems - Equine odontoclastic tooth resorption and hypercementosis (EOTRH)
○ Resorption of bone around incisor teeth -> radiograph to diagnosis
in terms of premolars and molars how to examine, how much grow and main issue
- Teeth most often ‘floated’ (filed)
- Difficult to examine properly
- Erupt (not grow) at approx. 2-3(4)mm per year
- Reduce in rostro-caudal length with age
- May affect performance
Eruption bumps what are they, where commonly occur and due to
- Eruption cysts: ○ Bilateral, non-painful ○ Mandible and, less commonly, maxilla ○ DDx: Periapical disease - Due to ‘frustrated’ permanent teeth -> permanent teeth continue to grow without deciduous teeth being removed yet
what are the main pathology seen in the cheek teeth and where
- Malocclusions
○ Hooks, Ramps, Steps, Excessive transverse ridges (ETR), lateral edges, ulcers etc.
§ Hooks -> commonly develop on P2 upper arcade and M3 lower arcade - Fractured teeth, patent infundibulae
- Periapical Disease - around tooth
- Periodontal Disease - around the gum
why do horses get sharp edges and where occur
- Anisognathic-different sizes and shapes
○ Maxillary aracade 30% broader and curved (compared to mandible) - THEREFORE will get Outside (buccal) of maxillary (upper arcade) and inside (lingual) of mandibular (lower arcade) will get sharp edges
○ Need circular grinding motion to avoid this
periapical disease what is it, cause and diagnosis
- Inflammation, usually infection, of the apices of the teeth. (Upper M1, M2, PM4, Lower M1)
- Etiology:
○ Bacterial diapedesis (translocate from capillaries) through damaged gingiva
○ Haematogenous - Diagnosis:
○ Clinical signs
○ Oral examination
○ Radiographic examination (valuable, difficult to interpret)
§ See radiolucency, and draining fistula
○ Nuclear Scintigraphy, CT or MRI
tooth removal (exodontia) what is the preferred way and what other way can do it, what need to beware of
- Intra-oral extraction-ideal but technical
- Surgical removal - anaesthesia
○ Repulsion with a bolt and hammer - cause trauma/damage and increase potential for bone infection
○ Lateral buccotomy -> cut the check and access tooth on the side - Complication rates approach 50% ** BEWARE
What is the 2 main nerve block done during equine tooth removal and the 2 main brancches
1) trigeminal
- infraobital branch
- mental branch
2) local
In terms of the infraorbital branch of the trigeminal branch for teeth extraction where done, what blocks and anatomical landmarks with size of needle and amount of anaesthetic
○ Maxillary foramen (entrance) - complications
○ Infraorbital foramen (exit) - more user friendly
○ Carefully infiltrate into foramen
○ Blocks - skin to muzzle, upper incisors to cheek teeth (cheek teeth depends on how far move up the infraornital sinus)
○ Anatomical Landmarks Infraorbital (foramen)nerve block
§ Thumb over - Naso-incisive notch
§ Finger on -> Facial Crest
§ Levator nasolabialis muscle over the infraorbital foremen
§ Index finger -> Infraorbital foramen
§ 22G-40mm needle
§ 8-10ml local anaesthetic and adequately sedate
Mental branch of the trigeminal nerve for teeth extraction where can be done, what does it block and the anatmocial landmarks
○ Mandibular foramen (entrance)
○ Mental foramen (exit)
○ Blocks - Incisors and rostral mouth NOT CHEEK TEETH
○ Anatomical landmarks
§ Chin crease
§ Palpation -> rostral foramen, mental nerve
§ 22 G 40mm needle 8-10ml local anaesthetic
Local anaesthesia for tooth extraction what useful for, limited to, where blocking and what need to avoid
- Useful for wolf tooth and incisor extraction
- Limited use for cheek tooth extraction
- Block medial and lateral to tooth
- Avoid major palatine artery
What are the mild, moderate and severe clinical signs of colic
mild - Off feed (inappetence) - Dull/quiet - Flank watching Moderate - Lying down - Pawing Severe - Rolling/crouching - Uncontrollable/violet
what are the 3 causes of abdominal pain and what level of pain
- Dysmotility - mild
- Distention/tension on mesentery - moderate
- Ischemia - severe pain
clinical approach to colic with mild pain
- dysmotility/mild distension
○ Physical exam/history
○ CV compromise
§ NO -> NGT (nasogastric tube), rectal exam (abnormal -> NO then likely medical treatment and recovery 3-4 hours), ultrasound, abdominal tap
Clinical approach to colic with moderate pain
dysmotility, distension, ischemia ○ Physical exam/history ○ CV compromise § No -> NGT, rectal exam (abnormal) □ NO -> ultrasound, abdominal tap -> treat and recovery 2-3 hours □ YES -> likely surgical § Yes -> likely surgical
Clinical approach to colic with severe pain and what is respond and don’t respond
significant distension, ischemia
○ TREAT PAIN and NGT (if yes to this then likely surgical) -> need to relieve the distention
§ Response -> physical exam/brief history, CV compromise
□ NO -> rectal exam, ultrasound, abdominal tap -> abnormal
® NO - reassess 2-3 hours
® YES -> likely surgical
□ YES -> likely surgical
§ Doesn’t respond -> need more sedative and then move to response
In terms of history for colic case what are the horse and management factors need to consider and the 2 critical things to as
- Horse factors:
○ Duration /severity of pain – is it escalating? - CRITICAL
○ Any drugs given, dose/route and how long ago? - CRITICAL
○ Previous colic (surgery) - CRITICAL
○ Manure passed today (mild-moderate)
○ Age of horse /purpose /(insurance status) - Management factors:
○ Change in feed/ management past few weeks
○ Previous episodes of colic
○ (Recent worming) - if have a high burden when dewormed then possible inflammatory response to the dying worms - not common
What properties for NSAIDS, apha-2 agonists and ketamine
- NSAIDS are anti-inflammatory with analgesic properties
○ Flunixin/phenylbutazone - pick one - Alpha 2 agonists are sedatives with analgesic properties
○ Detomidine/xylazine - Effects are complemented with opiates
○ Butorphanol (morphine/methadone (avoid in colic due to ileus) - Ketamine is an anaesthetic with analgesic properties - not appropriate for analgesia
in terms of interpretation of pain for colic what is involved
- Duration /severity of pain –is it escalating?
○ Severity determines possible lesions
○ Lesions can progress
○ Longer duration (hours) suggests more likely to need intensive treatment /surgical- correlate with CV status
○ Finite duration of ischaemia before CV collapse and death
what are the 2 main short-term visceral analgesics, their onset and duration, and when to use
○ Alpha 2 agonists: rapid onset, variable durations
§ xylazine: 20-30 minutes (200-250mg /500 kg IV)
§ detomidine: 40-60 minutes (0.5ml /500 kg IV)
○ Opiates: rapid onset, augments sedation
§ butorphanol: 30-40 minutes (0.5-1ml /500kg IV)
§ morphine: hours (avoided in colic: ileus)
- Use detomidine and butorphanol for severe pain
- Use xylazine alone for lower grade pain or procedures
what type of drug used for longer term pain relief with colic, the 3 main drugs, duration and potency
NSAIDS
1) Flunixin: 0.5 -1.1mg/kg IV - most common
§ Duration 12-24 hours, onset 40 minutes
§ Potent visceral analgesic at high dose
§ Improves appearance of mmbs - keep in mind when reassessing horses
2) PBZ: 2.2- 4.4mg/kg IV
§ Duration 12-24 hours, onset approx 40mins
§ Less potent than flunixin for visceral pain - debatable
§ Oral phenylbutazone: 2 hours for effect
3) Buscopan: ‘Antispasmodic’ + weak NSAID -> not for significant GIT pain
§ Relatively poor analgesic compared with others
Sedatives for colic cases what is the main type and 2 drugs and duration used
○ Strong visceral analgesics - short acting analgesics - important to know duration
§ Alpha 2 agonists: rapid onset
□ Xylazine: 30 mins duration
□ Detomidine: 60min duration
what are 3 main risk factors for colic and why within
1) Change in feed/ routine past few weeks
○ Large amount of grain- fermented in large intestine
○ Lucerne hay- gas production
2) Previous episodes of colic
○ Management influential
3) Recent worming
○ Colic 1-2 days after worming
○ Presumed disruption of motility
○ Can be severe and surgical
○ Intestinal inflammation when worms are killed
○ Worm ‘injury’ uncommon these days
Physical examination for a horse with colic what is the 8 main things to do
1) assess level of pain
2) cardiovascular status
3) temperature
4) mucous membrane colour
5) abdominal distention
6) gut sounds - very subjective
7) nasogastric intubation (NGT)
8) rectal examination
placing a stomach tube in a horse what should you do
- Ensure tube remains ventral and central (within the ventral meatus)
- Once get to larynx will have resistance and then twist 180degrees
- Ensure the head is flexed for this
in terms of cardiovascular and temperature for physical examination of colic horse what is involved and what does this indicate
- Cardiovascular status
○ Ischaemia/endotoxaemia: hypovol +CV compromise
§ HR >60, RR >20, delayed crt, poor peripheral pulses - surgical lesion
§ injected/congested/toxic mmbs
§ Early ischaemic lesions can have normal CV - Temperature
○ See febrile causes: rarely surgical
○ May still need intensive treatment
Abdominal distention detection during colic physical exam what generally represent and significance
○ Large intestine in an adult
○ Large or small intestine in immature animal
○ Always significant
○ Often surgical
