Week 1 Flashcards
What are the 4 main salivary glands in dogs & cats?
Parotid
Zygomatic
Mandibular
Sublingual
Where can minor salivary glands be found
caudal 3rd of tongue
buccal mucosa
labial mucosa
soft palate
Label the salivary gland diagram
Describe the structure of the parotid gland
Just ventral to base of ear
Mixed mucus & serous saliva
single duct
becomes swollen in horses on new grass (parotiditis)
Duct runs from surface of gland across masseter muscle (dog, sheep) or ventral to it (cattle, horse, pig)
Opens in upper buccal area by maxillary 4th premolar (upper carnassial) tooth
Describe structure of zygomatic gland
Only in dogs & cats
dorsal buccal gland in other mammals
Duct opens in upper buccal mucosa opposite upper 1st molar (tooth no. 109/209) or caudal to this
Duct usually caudal to parotid duct opening & may have several (~4) minor openings of same gland nearby. Often seen as ridge with several small red dots
Describe structure of sublingual gland
Have polystomatic (many holes) part & monostomatic (1 hole) part
Monostomatic part has long sublingual salivary duct which runs next to mandibular salivary duct & opens with it at sublingual caruncle
In dogs polystomatic part comprises 6-12 lobules with independent short salivary ducts opening sublingually near frenulum.
Mucus mainly, with lesser serous component
Describe structure of mandibular gland
Connective tissue capsule is shared with monostomatic part of sublingual salivary gland
Duct opens at sublingual papilla (caruncle) at base of lingual frenulum
In 30% of dogs the mandibular and sublingual ducts merge
Mixed mucus/serous, but can alternate
Describe saliva components
Colourless, slightly opalescent liquid
98-99% water
Contains small amounts of:
Electrolytes
Proteins
Carbohydrate splitting enzyme (amylase)
Desquamated cells from mucosa
Lymphocytes
Mucin, if mucus secreting gland
Primary secretion made by epithelial cells within acini
Describe saliva modification
Primary secretion leaves acini
Modified in ducts
- Na and Cl resorbed
- HCO3 (important for ruminants for buffering) & K secreted
Osmolarity depends on flow
The greater the volume produced the closer to primary secretion concentrations achieved
Faster flow = less time in ducts = less modification
Slow flow = hypotonic.
Label the saliva duct
What are the salivon cell types
Serous cells – watery secretion
Mucous cells – mucus secretion
Plasma cells – around the acini produce IgA
Myoepithelial cells - envelope each acinus
Contract & push saliva down into mouth
Intercalated ducts – secrete HCO3- and absorb Cl-
Striated ducts – secrete K+ & HCO3- & absorb Na+
Secretory ducts – convey saliva to mouth (multiple or single ducts)
Describe saliva functions
Wetting agent / lubricates:
Moistens food bolus, eases mastication (chewing) & swallowing (deglutition)
Lubricates oral mucosa:
Mechanical washing of surfaces of teeth & mucosa to remove food, debris, microbes
Water soluble food components dissolve in saliva
Enzyme action:
Amylase (high in pigs) to aid carbohydrate digestion
Buffering action in rumen:
Bicarbonate needed to regulate acidity
Bicarbonate buffer keeps oral pH in dogs & cats +-7.5
Phosphate buffer & aid to microbial growth to enable digestion
Hydroxyapatite in saliva provides Ca ions to maintain enamel, but also mineralises dental plaque causing calculus
Anti-foaming
Peroxide-based antibacterial system
How is salivary secretion regulated
Balance of sympathetic & parasympathetic autonomic NS
Sympathetic:
Viscous, amylase, more protein
Low volume
Dry mouth
Parasympathetic:
Watery, high volume
Increased flow in response to taste, visual & olfactory stimuli
Continuous basal flow …. even when asleep
Reflex:
In ruminants presence of long fibre in reticulum near cardia stimulates salivary flow
Automatic:
Taste & smell
Composition
Conditioned:
Indirect; Pavlov’s dogs.
Describe the autonomic nerve supply for salivary glands
Sympathetic supply reaches glands via arterial supplies
Parasympathetic supply travels along trigeminal nerves even though nuclei are linked with cr.nn
VII = mand., subling., palatine
IX = parotid (& zygomatic)
Describe suckling in mammals
Presence of hard palate
Freely mobile tongue
Allows suckling and breathing together
Can drink by sucking,
Dogs and cats lap with a curled tongue
Three seals:
Lips
Tongue against soft palate
Soft palate against epiglottis (not humans)
How do different animals cope with breating and swallowing?
Mammals able to hold food in mouths & still be able to breathe (also crocodilians)
Snakes have glottis rostrally between the mandibles
Fish expel xs water through gills then swallow
Birds have more rostral glottis which allows breathing whilst swallowing bulky items
Label the diagram
Describe swallowing
How do reptiles swallow
Secondary hard palate incomplete in many species
Lip seal poor or absent
Minimal chewing
Skull types affect prehension
Kinetic skulls allow jaw movements to assist prehension, most notable in snakes & fish
Remember extra jaw bones & joints NOT dislocation allow for different gapes!
Describe the pharyngeal wall (swallowing) innervation
Glossopharyngeal nerve (IX) and vagus nerve (X)
What are the muscles involved in swallowing
Constriction and shortening:
Rostral (Palatopharyngeus)
Middle (Hyopharyngeus)
Caudal (Thyropharyngeus)
All insert onto roof of pharynx > dorsal & lateral arches
Important for passage of food
Dilation:
Single muscle : Stylopharyngeus caudalis
What is the position of the soft palate during sucking
under epiglottis
What is the position of the soft palate during swallowing
elevated to allow food to pass into laryngopharynx
What is function of epiglottis during swallowing
covers trachea to prevent food/liquid from entering
How do non-mammals deal with combining breathing & eating
swallow quickly, relying on vocal cords to close glottis
How does anatomy of herbivore vs carnivore affect:
a. clinical signs of disease
b. examination
c. surgery
a. herbivores may show dental issues related to grinding & chewing fibrous plant material while carnivores may exhibit signs of dental or gum disease related to tearing & chewing meat
b. harder to examine herbivore cavity
c. surgical access easier in carnivores
Describe the role of different types of teeth
Incisors: nibbling, grooming, cutting
Canines: grasping, fighting/defence, stabbing, toxin injection
Premolars & molars: depends on diet, but variously crushing, shearing, gripping, grinding
What kind of teeth do snakes have
Pterygoid
Label the teeth terminology
Lingual = medial side of mandibular teeth
Palatal = medial side of maxillary teeth
Labial / buccal = lateral / cheek side
Label the teeth terminology
Describe homodont vs heterodont teeth
homodont:
all teeth similar
reptiles, fish, amphibians
heterodont:
teeth dissimilar
mammals, some reptiles
Describe monophyodont, polyphyodont and diphyodont
monophyodont:
adult set only
e.g. rodents
polyphyodont:
teeth continuously replaced
e.g. reptiles & fish
diphyodont:
2 sets of teeth
most mammals
What are hypsodont teeth
Most of tooth hidden in jaw bone (long crown)
what are brachydont teeth
1/2 of tooth in jaw & 1/2 visible (short crown)
What number does each type of tooth end with
Deciduous: 5xx-8xx
Permanent: 1xx-4xx
Incisors: x01-x03
Canines: x04
Premolars: x05, x06, x07, x08
Molars: x09, x10, x11
What is mare dental formula
How to carnivores vs omnivores vs herbivores chew
Carnivores:
Moved jaw sideways to engage carnassial teeth - Pterygoideus muscles
Close jaw to shear/crush - Masseter & temporalis muscles
Omnivores:
Combined crush/grind action
Herbivores:
Close jaw on herbage - Masseter muscles
Move jaw sideways whilst held closed = grinds plant material - Pterygoideus muscles are large since working under load, Equalled by masseter muscles
What is diastema
Describe carnivore teeth
Brachydont
Erupt to set height
Teeth serve multiple functions:
Incisors: nibbling/nipping
Canines: puncture/grasp
Carnassials: cut/shear
Molars: crush
Jaws have to move laterally to bring carnassials into action
Cats = 30
Dogs = 42
Dog dental formula
Cat dental formula
What are carnassial teeth
208 & 309
What kind of dogs have dental issues
Brachycephalic breeds:
Jaws bred to be short, hence far less room for teeth
Dolichocephalic breeds:
Mandible is shorter than maxilla/incisive
Usually cope well
Few clinical problems due to this conformation
Describe herbivore teeth
Hypsodont – long/high crown (clinical vs anatomical)
Most of tooth is hidden within socket
Hence all of tooth enamel is covered by cementum, since when tooth is in bone, supporting ligaments unite with cementum
Flat surfaced
Folded enamel (like a curtain)
Grinding
Continuous eruption/growth to match wear
Horses/ruminants = slow tooth eruption
Small furries = slow tooth growth plus eruption
How can you tell horse age by teeth
Only look at lower incisors
2.5yr - 01 erupts
3.5 yr - 02 erupts
4.5 yr - 03 erupts
What are tushes
equine canine teeth
not a clinical problem
stallions & geldings
what are wolf teeth (equine)
First PM of upper jaw (105, 205)
Rarely first PM of lower jaw (305, 405)
Redundant regressed teeth
Both sexes
Appear at 3-5 yrs old, if at all
3 mm to 20 mm total length
Small ones wobble & interfere with bit – remove under sedation
Large ones quite stable and can be left in
describe rodent dentition
incisors (4 rabbit, 2 rodents)
premolars & molars
all open roots
Describe herbivore vs omnivore small animal dentition
Describe pig dentition
food trapped between occlusal faces & crushed/mashed
What are secodonts
cutting edges/shearing
carnivores
what are lophodonts
cusps as folded ridges
rodents, horses
what are selenodonts
cusps as crescents
bovidae
Label the diagram
Label the tooth
What is enamel
Hardest biological substance
Apart from limpet radula
97% hydroxyapatite
Acellular
No collagen (special support proteins instead)
No repair possible, but enamel calcium is in equilibrium with salivary calcium
Dissolves in acid
Only on crown
Not always present
What is dentine
Living tissue:
Odontoblasts produce dentine tubules
Cytoplasmic processes within dentinal tubules
Primary:
Most of dentine
Formed as tooth grows
Mineralized collagen
Secondary:
Grows slowly on daily basis
Formed after eruption
Makes pulp smaller
Tertiary:
Reaction to damage
Irregular structure
Helps to fill in damage
Label the tooth histology
What is pulp
Root canal
Blood vessels, lymph, nerves
2’ dentine deposition
Narrows with age
Closed apex
When finished erupting
Open apex
For continually erupting teeth
Apical delta
Many small canals at apex.
What is cementum
Similar to bone
Peripheral to dentine or enamel
Attachment for periodontal fibres
Completely covers herbivore teeth
describe the tooth root types
Closed:
Root apex closed off = do not grow once formed
Teeth erupt slowly and continuously - Horses, cattle
Teeth erupt to fixed height - Carnivores and omnivores
Open:
Root apex is open (=grows continuously elondont)
Teeth continually grow & erupt
Rodent and lagomorph incisors
Many rodents also have open root molars
Describe tooth development
Describe horse tooth eruption
Describe carnivore tooth eruption
Describe tooth maturation
As tooth grows, primary dentine grows, pulp remains large, open root
Mature tooth: secondary dentine gradually replaces pulp, closed root
what is periodontium
Collective term for supporting structures of tooth
Label the diagram
What is gingiva
Squamous epithelium
Dense fibrous layer
Closely bound to the periosteum
Reflects at cemento-enamel junction (CEJ) to form pocket, gingival sulcus
Site for food debris to be trapped
Site where inflammation starts (gingivitis)
What is periodontal ligament
Series of angled collagen fibres
Supports the tooth
Shock absorber
Spreads load into whole socket
What is temporo-mandibular joint
Synovial joint
Hinge joint, but also has:
Lateral movement and
Rostro-caudal movement
Allows for grinding & opposing of teeth
Well-developed meniscus:
Creates two synovial compartments
- Skull-side = translation movements
- Mandible-side = hinge movements
Label the carnivore closing masticatory muscles
Label the carnivore opening masticatory muscles
label the herbivore masticatory muscles
Label the arterial supply
Main mastication veins
Masticatory mm drain via maxillary vein & deep facial vein
drain into the external jugular vein
describe maxilla & mandible nerve supply & sites of nerve blocks
Maxilla
Infraorbital nerve (V2):
Enters maxillary foramen - Nerve block site
Sensory branches to tooth roots
Exits at infraorbital foramen - Nerve block site
Mandible
Mandibular nerve (V3):
Enters mandibular foramen - Nerve block site
What are dental nerve block sites
Fill in the table
How do mammals breathe & chew at the same time
By sealing off buccal cavity & oropharynx from common pharynx
Seal made by tongue against soft palate & soft palate against epiglottis
How do non-mammals cope with not being able to breathe while chewing
Dont chew - bite and swallow large food items quickly
What is a salivary mucocele?
Accumulation of saliva in tissues due to blockage of salivary gland duct which leads to formation of cyst like structure
Name cranial nerves for
1. olfaction
2. skin sensation of lips
3. lip movement
4. jaw opening
5. tongue movement
6. taste
7. jaw closing
8. swallowing
Which route would you use to pass a stomach tube in cattle, horses & dogs?
What is the embryological origin of ameloblasts and odontoblasts and what do they produce?
What happens to tooth pulp cavity with age
Reduces in size as secondary dentine is deposited by odontoblasts which reduces size of pulp chamber
What is the difference between primary & secondary dentine?
Primary dentine forms before tooth eruption and secondary after
Describe the anatomical form & features of ruminant, horse, pig & dog stomachs
What is the enamel organ?
Epithelial structure that sits above & around dental papilla.
Formation of enamel,
initiation of dentin formation,
establishment of shape of tooth crown,
establishment of dentogingival junction
What happens during bud stage, cap stage & bell stage of tooth development?
Gradual differentiation of various cell types of tooth
What is the function of dental sac?
Connective tissue structure that surrounds enamel organ & dental papilla during tooth development
provides cementum, alveolar bone & blood supply
Fill in the numbers of teeth table
Fill in the teeth eruption ages table
What is Vmax
theoretical saturation point
What is Km
substrate concentration at 1/2 Vmax
rate constant
indicator of enzyme affinity for substrate
What is enzyme inhibition
Enzyme inhibitors bind to enzyme & decrease its activity
competitive or non-competitive
irreversible or reversible
important for metabolic pathway regulation
Describe reversible competitive inhibition
Mimics substrate
substance competes directly with substrate for active site
Increases Km - lower affinity for substrate
No effect on Vmax
e.g. ACE inhibitors
Describe non-competitive inhibition
substrate & inhibitor bind at different site
causes change in 3D structure
enzyme able to bind both inhibitor & substrate
decrease Vmax
no effect on Km
e.g. allosteric inhibition in metabolic pathways
Describe irreversible inhibition
Forms covalent bond to amino acid near/at active site
permanently inactivates enzyme
e.g. aspirin
Define enzymes
proteins that function by accelerating chemical reactions in biological systems
reduce activation energy required for reaction to take place
What is induced fit substrate binding
Active site not always correct shape
when substrate comes close, molecular forces alter active site shape to allow substrate to bind
What is mechanism of enzyme catalysis
- substrate orientation (substrate correctly aligned)
- changing substrate reactivity (gives substrate charge)
- induce substrate strain (allows reaction to take place)
- exclude water (so substrate can remain in transition state)
What is the role of metal ions in catalysis
Co-factors
changes charge in active site
not used up
What are co-enzymes
organic molecules (vitamins)
deficiency disease (e.g. vit B)
high affinity for enzyme
couple reactions together
used up
e.g. nicotinamide adenine dinucleotide (NAD) which has role in energy release
List some examples where enzymes are used clinically
assays
looking at genetic diseases
vitamins
cofactor levels
What properties make enzymes excellent tools in clinical diagnostics
work at nice physiological conditions
quick results
specific to diseases
easy to detect
Describe oral mucosa
Is keratin present on the outside and inside of the lip?
Outside only
Label the lip histology
What are oral & lingual papillae and their functions
What are the tongue functions
Prehension
Food capture
Move food over teeth
Prepare bolus for swallowing
Catch ruminal bolus during cudding
Gustation
Suckling in neonates
Label the tongue
What are the extrinsic muscles of the tongue
Geniohyoideus
Genioglossus
Hyoglossus
Styloglossus
Mylohyoideus
Which nerve contains motor supply to intrinsic & extrinsic tongue muscles?
Hypoglossal nerve
Which nerves carry sensation to tongue
Facial nerve - taste
Trigeminal nerve - general sensation
Label the intrinsic muscles of the tongue
Label the muscles
What is wooden tongue
Bacterial infection that leads to nodule formation in soft tissue of tongue
Label the tongue histology
Label the tongue histology
What role does keratin perform in tongue
Structural support & protection
Why do gustatory papillae need to be wet
Sensitive to chemicals in food that are dissolved in saliva
Label the salivary glands
Label the salivary gland
Label the salivary gland
Label the mixed gland
What do myoepithelial cells do
contractile function
Label the oesophagus histology
Label the oesophagus histology
Label the tonsil
Do tonsils have lymphatic drainage like regional lymph nodes
Yes
Label the lymphoid tissue
Describe function of GI tract
What is autochthonous
Individuals personal commensal flora
established at birth
Describe carnivore diet & GI tract
What are the types of herbivores
Advantages & disadvantages of grass fermentation
What are some herbivore evolutionary adaptations
Describe omnivore diet & GI tract
Describe insectivore diet & GI tract
Describe arbivore diet & GI tract
Why do piscivores have simple GI tracts
Fish are nutrient dense so easy to absorb nutrients
Fish easy to breakdown so dont need fermentation chambers
Name an enzyme that digests fibre
cellulase
Describe smooth muscle of GI tract
Unitary/syncytial
all fibres contract as single unit
arranged in sheets or bundles
stretch leads to contraction
Describe oesophagus structure
deep folds when contracted - capable of massive expansion to accommodate food boluses
wall is 3 layered:
connective tissue adventitia
muscular layer
mucous membrane
tunica adventitia connects to neighbouring structures
tunica muscularis undergoes wavelike contraction to propel bolus to stomach or mouth
Label the oesophagus wall
label the oesophageal section
Describe the tunica mucosa (mucous membrane) of oesophagus
Label the oesophagus
Describe ruminant oesophagus
What is this (oesophagus)
What is this (oesophagus)
Label the oesophagus
Describe oesophagus blood supply
Describe oesophagus innervation
Compare carnivore to herbivore oesophagus
Shorter & more muscular in carnivores
Herbivores longer and has salivary glands that produce mucin to lubricate & moisten ingested material
What is megaoesophagus
Abnormally enlarged oesophagus
Describe features of foregut fermentation
Large structures
By product is gas
saliva buffers fermentation
coarse feed can be remixed several times for repeated digestion
products more easily available to intestinal absorption
digestion largely complete before LI
What are the ruminant forestomachs and what happens there
Reticulo-rumen & omasum
Label the camelid stomachs
Where is the forestomach in GI tract
Anterior portion of stomach
What are the different types of fibre
soluble (pectins & gums) & insoluble (cellulose & lignin)
What process is responsible for digestion of fibre in forestomachs
microbial fermentation
Where do fibre digesting enzymes originate from
Microbial enzymes produced by bacteria & protozoa
What is the difference between cellulose & lignin? are they digested in ruminant GI tract?
Cellulose is complex carbohydrate & main structural component of plant cell walls. partially digested in rumen
lignin is complex non-carbohydrate polymer that provides plant cell wall rigidity. not digested
Describe stomach structure & function
Why can’t horses vomit & what clinical issues does this cause
Have weak cardiac sphincter compared to other animals & oesophagus enters stomach at acute angle. Inability to vomit can lead to gastric rupture or colic
What stomach regions are keratinised vs glandular
Label the different stomach regions
How many stomach muscle layers do horses have
3
normal longitudinal (outer) & circular layers
extra inner oblique muscle layer
Name structures in foregut of chicken
Crop
proventriculus
gizzard
Name 4 regions of stomach & their functions
Cardia - receive digested food from oesophagus & initiate digestive process
fundus - store ingested food temporarily
corpus - mixing & grinding food with gastric secretions
pylorus - mixing & propulsion onwards into SI
name the stomach secretions & their nature
What is chyme
semi liquid mixture of partially digested food, gastric juices & digestive enzymes
What is the small intestine divided into
duodenum
jejunum
ileum
What are the small intestine functions
Fill in the table
Bile important in species which have fat in diet
describe pancreas structure
What is pH of secretions in small intestine
alkali to neutralise stomach acid
What is the brush border
microvilli on surface of epithelial cells that increase surface area for absorption
Which 5 cell types are found in mucosa of SI & what are their functions
enterocytes - absorption
goblet cells - secrete mucus
paneth cells - secrete antimicrobial substances
enteroendocrine cells - secrete hormones
M cells - initiate immune response
Which nutrients are primarily absorbed in SI
monosaccharides
amino acids
fatty acids
glycerol
vitamins
minerals
water
Describe hindgut fermentation
What is the caecum
Well developed in hindgut fermenters
What is the role of the caecum
Fermentation & absorption of nutrients
reservoir for material moving to colon
appendix attachment
Describe large intestine structure
Describe LI function & species differences
What are the main functions of Large intestine
water & electrolyte reabsorption
fermentation of undigested material
storage of faeces
bacterial flora for fermentation
Compare histology of SI vs LI mucosa
Describe avian digestive tract
Label the bird GI tract
Label the bird GI tract
What are fish spiral valves
Lengthen path ingesta has to travel in intestine
Label snake GI tract
Describe development of gingivitis
Plaque develops changing the microenvironment
Anaerobes can establish
Mineral deposition can occur
Sub-gingival deposits and growth will trigger inflammation
Bacteria also secrete enzymes weakening tissue causing more damage
Describe flora distribution on teeth
Plaque formation on teeth is not uniform
Depends on degree of protection from oral removal forces & gradients of biological factors from host
Consider:
How much of the surface is washed with saliva
What contact is there when chewing
Distinct sites such as
Gingival crevice
Smooth surfaces
Pits and fissures
Allogenic vs autogenic plaque development
Allogenic due to factors of non microbial origin
i.e. tooth eruption, addition of dentures, diet change
Autogenic due to changes in microbiology
i.e. development of food chains, low redox environments
Label the diagram
Describe oral mucosal surfaces as a habitat
Stratified non-keratinized epithelia
Protects underlying structures
Not sterile has population of commensal bacteria
A barrier to deeper infection
Layers can be worn off and replaced
Houses immune cells in tissue
If damaged can initiate inflammation
What is gingival crevice fluid
GCF is serum component
Increased production of GCF during infection can lead to localised small rises in pH. Can shift types of bacteria that grow
Enzymes: collagenase, elastase & trypsin in GCF can contribute to tissue destruction
GCF also has antimicrobial properties
(carries IgG)
It can contain Leucocytes
Describe non-specific (physical) factors in oral cavity
Describe dental plaque development
Why do bacterial populations change over time in plaque?
As plaque develops on tooth do does environment around & within plaque
There is progression from pioneer species followed by further bacteria as food web develops & more anaerobic conditions start to form
The more bacteria the more reduced environment as bacteria use up oxygen allowing anaerobes to grow
Growth of black pigmented anaerobes highly indicative of poor dental health
How does an anaerobic microenvironment form in plaque?
Oxygen has to diffuse into the plaque from the air
As O2 is used for bacterial respiration (it is reduced)
This develops an anaerobic (reduced) ‘respiratory’ environment
General rule of thumb is the more bacterial growth the more reduced/anaerobic environment
Anaerobes required reduced/anaerobic conditions for their respiration
What is dental plaque
a biofilm composed of bacteria & saliva that builds up on teeth
What is calculus
Mineralised phosphates deposited around the bacteria
Can occur subgingival or supragingival
Presence increases with age
This close contact with periodontal pathogens can lead to stimulation bone resorption (host mechanism)
Once formed a lot of force required to remove it
Dental products may include compounds to reduce mineralisation
Describe Streptococcus sp. (oral)
Genus: Streptococcus
Gram +Ve
Facultative anaerobes
Fastidious (requires enriched media)
Range of haemolytic activities
Found in all animals
Linked to number of diseases (Bacterial species & site dependent)
Can also cause opportunistic infection
In human dental disease linked to peridontitis
Describe Actinomyces (oral)
Genus: Actinomyces
Gram +Ve
Slow growth rate
Colonise mucous membranes
Opportunistic pathogen particularly oral cavity infections
Colonies form branched networks of hyphae
(do NOT confuse with fungi)
In rare cases, these bacteria can cause Actinomycosis
Genera is common in the environment (including soils)
Describe Neisseria (oral)
Gram negative
Diplococci
This genera colonize the mucosal surfaces of many species
Common isolate from oral cavity of dogs and other species
Requires oxygen but some prefer increased CO2
Describe Prophyromonas (oral)
Gram –Ve
Anaerobic
Rod-shaped bacteria
Produces porphyrin pigments (dark brown/black pigments)
Presence correlates with periodontal disease in humans, some non-human primates & beagles
NOT zoonotic so there must be bacterial/host species differences
Describe cat bite abscesses
Very Common in Small Animal Practice
Pyrexia is common
Results in inappetence and depression
Other clinical signs may result from spread to deeper structures (Bone, muscle, CNS)
Abscess may not be apparent on clinical examination
An abscess is:
A trapped collection of bacteria and cell debris (pus)
A defensive reaction of tissue - prevents spread of infection
An inflammatory response
Attracting white blood cells
Increasing the regional blood flow
Define pyrexia
fever
How does dental decay occur
What are feline odontoclastic resorptive lesions
Chronic accumulation of microorganisms
Endothelial and epithelial production of cytokines
Initiation and stimulation of odontoclastic activity
Stem cells attracted to the sulcus area by the cytokines
Instead of forming into macrophages, stem-cells become clast cells
Clast cells dissolve mineralised tissue
Clast cells multinucleated giant dissolve the tooth tissue
What is Candidiasis?
Candidiasis is mainly a disease of keratinized epithelium
Infections observed in immunosuppressed or where there are other chronic oral diseases
Appearance:
White pseudomembranous covering greyish plaques with some ulceration
Candidiasis recognised by budding yeasts with pseudo-hyphae or true hyphae in cytology
What is lumpy jaw (Actinomycosis)?
Cause: Actinomyces bovis
Route of infection: Mucosal commensal, invades tissue through breaks in lining of mouth. Damage due to rough forage or sharp tooth damage
Pathology:
Tumor-like hard swellings slowly develop (several months to be noticeable) on upper & lower jawbones of cattle
Lumps consist of honeycombed masses of thin bone filled with yellow pus
Advanced cases can discharge small amounts of sticky pus containing gritty yellow granules
Most common treatments are iodine therapy or tetracycline’s – or PTS
What is wooden tongue?
Cause: Actinobacillus lignieresii, Gram –ve, facultative anaerobe
Source: Commensal of mucous membranes
Route of infection: Invasion through breaks in lining of mouth due to abrasion by rough feed
Pathology: Sudden onset with tongue becoming hard, swollen & painful. Chronic pyogranulomatous inflammation of soft tissue. Infection usually limited to soft tissue of tongue & lymph nodes of head
What are some rabbit teeth adaptations
What are rabbit chisel shaped teeth
What does rabbit cheek teeth refer to
molars & premolars
What are rabbit peg teeth
2 “extra” tiny incisors
Sit just behind upper incisors
At rest – tips of lower incisors rest against upper peg teeth
Help with occlusion and wear
What is rabbit mandibular arcade
Lingual edge of maxillary teeth occludes with buccal edge of mandibular teeth
Label the lateral rabbit dental radiograph
What views are used for dental radiography
Lateral
Latero-oblique
dorsoventral
In what view is this radiograph taken
Latero-oblique
head tilted by 10-20 degrees
In what view is this radiograph taken
Dorsoventral
in ventral recumbency
What is dental burring
Indications
Incisor overgrowth
Cheek teeth overgrowth
Aim
Remove any spikes
Restore normal anatomy
Caveats
Not long-term solution
Need to correct underlying cause
Not enough for abscesses
Label the dentistry equipment
Label the molars equipment
Label the incisors equipment
What are the causes of dental disease in small mammals
DIET
Not enough vegetation
Selective eating
Sugary treats and fruit
Vitamin C deficiency (guinea pigs)
Selenium deficiency
Ca/P imbalance (metabolic bone disease)
Breeding
Inherited predisposition
Brachycephalic conformation
Acquired dental disease
Including secondary overgrowth
Congenital abnormalities
Prognathism, incisor malocclusion
Trauma
Incl. tooth/jaw fractures
What is PSADD in rabbits
Progressive syndrome of acquired dental disease
Accounts for most rabbit dental disease
Apical elongation
Crown elongation and curvature
Enamel spurs
Acquired malocclusion
Enamel hypoplasia
Dental abscesses
What are the early stages of rabbit PSADD
Apical elongation
First change
Eruption slows or stops due to reduced wear
Pressure on nasolacrimal duct, nerves
Can penetrate bone on ventral mandible
Palpable
What are the intermediate stages of rabbit PSADD
Acquired malocclusion
Malocclusion, abnormal wear – vicious cycle
Incisors and cheek teeth
Crown elongation and curvature
Enamel spurs
Soft tissue damage, inflammation & pain
What are the late stages of rabbit PSADD
How can small mammal dental disease be prevented
Diet diet diet…!
Lots of grass and good quality hay
Small amount of pellets, no muesli
Feed appropriate diet for age and species
Guinea pigs and vitamin C
Adequate calcium for growing/breeding animals
Feed weeds, wild plants & fibrous veg(e.g. broccoli, cabbage, spring greens)
Only feed root veg or fruit as a treat
Avoid sugary treats
Encourage/allow gnawing behaviours
Selective breeding and culling
Signs of periodontal disease
bad breath
loss of appetite
mouth pain
drooling
What is the difference between plaque & calculus
Plaque is precursor of calculus
Calculus is mineralised & hardened & firmly adheres to teeth
Which changes in plaque make it a potential cause of periodontal features?
Gingivitis (plaque accumulates at gum line leading to irritation & inflammation of gingival tissues)
periodontitis (untreated gingivitis, inflammation is deeper into surrounding structures of teeth & body’s immune response leads to breakdown of gum tissue & bone)
What advice would you give to an owner to prevent further build up of plaque on cats teeth?
regular check ups
dental cleaning
dental diet
dental chews
brush teeth
no human food
monitor teeth
How does osteoclast formation (osteoclastogenesis) occur?
RANK pathway
1. inflammation leads to recruitment of immune cells
2. cells in periodontal tissue (e.g. osteoblasts) produce RANKL
3. binds to RANK & stimulates differentiation into mature osteoclasts
Why is osteoclastogenesis important in periodontal disease?
When osteoclastogenesis becomes unregulated, bone resorption increases & weakens bone around teeth
Describe the stages of periodontal disease
- gingivitis: plaque formation, gingival inflammation
- early periodontitis: gingival pocket formation (inflammation of gingiva extending deeper into roots - bacteria & plaque accumulate), early bone loss
- moderate: increased pocket depth, further bone loss, formation of periodontal abscess, pocket may become sites of pus collection
- advanced: severe pocket formation, extensive bone loss, tooth mobility & loss, soft tissue recession
What factors predispose cats to periodontal disease
diet
age
oral hygiene
obesity
tobacco smoke exposure
Define vesicle
circumscribed epidermal elevations in skin containing clear fluid & usually less than 5mm in diameter
Define bulla
If vesicle has diameter of greater than 5mm, its called a bulla
Define erosion
Partial loss of epidermis that doesn’t penetrate beneath basal laminar zone
Define ulcer
Loss of epidermis & dermis (& sometimes deeper tissue)
Name common notifiable vesicular diseases that cause oral lesions in farm animals
Foot-and-mouth disease (FMD)
Swine vesicular disease (SVD)
Vesicular stomatitis (VS)
How does Foot and Mouth disease spread
Predominantly by respiratory infection
Ingestion of contaminated food or direct inoculation are also effective
FMD spreads rapidly in previously free country (like UK) due to highly contagious nature of virus & lack of immunity in susceptible animals
Therefore FMD is a notifiable disease in the UK
Caused by Apthovirus
Describe Foot and Mouth disease epidemiology
Virus extremely infectious & contagious
Rapid replication cycle, high virus yield
Large volumes of aerosols, virus stable
Short incubation period
Virus excreted up to 4 days pre-clinical signs
Carriers – virus persists in pharynx (not pigs)
Transmitted by animals/contaminated items/people environment, windborne
What are the clinical signs of FMDV in cattle
Incubation 2-8 days
fever, loss of appetite & marked drop in production of milk
Within 24hrs, profuse salivation-drooling, vesicles develop on tongue & gums
Vesicles may also be found on teats & coronary band of feet (interdigital cleft) - Lameness
Smacking of lips - oral vesicles rupture
Ruptured vesicles – large denuded ulcerative lesions
Secondary bacterial infection - mucopurulent nasal discharges
Pregnant cows may abort - as consequence of fever - virus doesn’t cross placenta
What are the clinical signs of FMDV in pigs
Lameness is the first sign
Foot lesions can be severe & very painful - prevent pig from standing
Vesicles within the mouth are less prominent than cattle
Large vesicles that quickly rupture often develop on snout
How if FMD diagnosed
Laboratory diagnosis is essential
Samples: Vesicular fluid, epithelial tissue from edge of vesicle, blood in anticoagulant, serum & pharyngeal fluid
Detection of FMDV antigen in tissue & fluid samples by ELISA
Can use pharyngeal fluid from recovering animals
PCR for the detection of viral nucleic acid
How is FMD controlled
In countries free from FMD it is notifiable:
- Exposed and affected animals are culled- ‘Stamping out’
- Rigid enforcement of quarantine & restriction of movement
In endemic countries:
- Inactivated vaccines are used
How does VSV spread
Virus enters body through breaks in mucosa & skin - minor abrasions & arthropod bites (e.g. mosquito, sandflies)
Vesicles develop at the site of infection
What are the clinical signs of VSV
Incubation period of 1 to 5 days
Fever & excessive salivation first sign in cattle & horses
Lameness is the first sign in pigs
Vesicles, blisters on oral mucous membrane, produces excess salivation
Vesicular lesions on teats, coronary bands, snout
Lesions usually heal within 7-10 days
How are viruses diagnosed
Detection of viral antigen: by immunofluorescent antibody staining of vesicle tissue or ELISA on vesicular fluid
Serology: Demonstration of rise in antibody titre by ELISA
RT-PCR: detect viral RNA
Isolation of virus : in cell culture
How is VSV (vesicular stomatitis virus) treated
Specific treatment NONE, try to minimize secondary infection (insect proof buildings, avoidance of insects)
How is VSV controlled
Vaccines available but generally not used
Movement restrictions & quarantine for 30 days post last case
What causes cat flu
FCV or FHV
What are the clinical signs of feline calicivirus
Causes acute or sub-acute disease
Incubation period is 2-3 days & recover in 7-10 days when disease not complicated by secondary bacterial infections
conjunctivitis, rhinitis, tracheitis, pneumonia & vesiculation & ulceration of oral epithelium
Fever, lethargy, anorexia, & stiff gait are also common
What are the clinical signs of feline viral rhinotracheitis
Incubation period 24-48hrs
Sudden onset of sneezing, coughing profuse nasal & ocular discharges, corneal ulcers
Acute disease is very similar to feline calicivirus infection
Profuse frothy salivation & corneal ulcers more common in FHV while ulcers of tongue & palate more common in FCV
What are other causes of oral vesicle formation?
Autoimmune diseases:
- Pemphigus vulgaris - Rare – usually dogs
- Oral, skin and mucosal surfaces
- Antibodies are directed against intracellular layers above basal cell layer
- Causes separation of epidermal cells from underlying tissue
- Diagnosis requires biopsy
- Severe disease with systemic signs (pyrexia, depression)
Toxicity:
- Other diseases may give crusty skin lesions with ulcers
- e.g. Primary photosensitisation due plant ingestion (e.g St Johns wort, alfalfa)
- e.g. Secondary to liver disease
- e.g. Phenylbutazone toxity in horses (oral ulcers)
What are Hox genes
DNA sequences that regulate pattern of development in embryos
Where hox genes overlap or change, a valve or change of structure occurs
define neurulation
formation of neural plate & its infolding to form neural tube
define somitogenesis
Occurs at same time as neurulation
development of paired blocks/bodies (somas) of tissues along length of developing embryo
Describe embryology of gut tube
Forms from endoderm following cephalocaudal & lateral folding of embryo
endoderm forms epithelial lining of digestive tract
mesoderm forms muscular & peritoneal components
How do buccopharyngeal & cloacal membranes form
2 small circular areas of embryo dont have mesoderm so ectoderm & endoderm in direct contact
at head & tail of embryo
these become buccopharyngeal & cloacal membranes
How are thoracic, cardiac & abdominal cavities formed
Splitting of mesoderm to create a space
Split forms extra-embryonic coelom, somatic mesoderm & splanchnic mesoderm
Splitting continues until it reaches embryo & stalk becomes umbilical cord
GIT is pinched off yolk sac
How does the yolk sac form
From blastocoele as embryo rolls up
- links to midgut
- becomes choriovitelline placenta
How does allantoic sac form
As an outgrowth of hindgut
- Root with gut becomes divided by urorectal septum to create hindgut & bladder
- becomes chorioallantoic placenta
What is a mesentery
Fold or membrane that conveys blood vessels, nerves & lymphatics to/from a visceral structure
How does the tongue develop
As outgrowth from mesoderm of lower jaw
Projects forward
How does the oesophagus develop
Develops as part of foregut, separated from developing respiratory tract bud by oesophagotracheal septum
Lengthens rapidly as embryo grows
Outer layers of striated muscles are formed from surrounding mesenchyme
How does the stomach develop
Forms from dilation of foregut
- gut tube around stomach is suspended by dorsal & ventral mesogastrium
Developing stomach undergoes rotation around longitudinal & cranio-caudal axis
- original caudal wall grows quicker to form greater curvature
Dorsal mesogastrium (left) forms greater omentum
Ventral mesogastrium (right) forms lesser omentum which connects to liver
How does the small intestine develop
Jejunum undergoes lengthwise growth & herniates from abdomen
Coils in on itself as its drawn back into abdomen as fetus grows
Rotation draws duodenum & large colon anticlockwise
What is an umbilical hernia
Faulty closure of abdominal wall leaves greater opening
Herniation of fat then SI through umbilicus
Heriditary
What are clefts & some examples
Persistence of embryonic/fetal clefts due to abnormal growth processes
Define aplasia
absence of part or all of an organ
Define hypoplasia
reduced development of an organ
Define atrophy
acquired reduction in size of an organ
e.g. disuse, nutrition, blood supply, hormones
Describe development of liver
Involves inductive & growth factor signalling from septum transversum & cardiac mesenchyme
Splanchnic mesenchyme contributes to sinusoids, liver capsule, connective tissue stroma, falciform ligament & muscle of biliary tract
Where does the spleen develop
In dorsal mesentery
What is the vitelline artery
Initially supplies yolk sac & forms plexus around gut
Forms arterial blood supply to gut:
- coeliac artery
- cranial mesenteric artery
- caudal mesenteric artery
What organs does the coeliac artery supply
stomach
duodenum
pancreas
liver
spleen
what organs does the cranial mesenteric artery supply
stomach
duodenum
pancreas
jejunum
ileum
large intestine
what organs does the caudal mesenteric artery supply
large intestine
What is the hepatic portal vein (embryology)
List some radiation safety precautions
Describe latero-lateral view for dental x-rays
Describe dorsoventral 30º lateral oblique view for dental x-rays
Skylines maxillary apices on side adjacent to cassette
Describe ventrodorsal 45º lateral oblique view for dental x-rays
Skylines mandibular apices on side adjacent to cassette
Describe dorsoventral view for dental x-rays
Describe intraoral view for dental x-rays
What abnormalities can you see and what medication would you give
Calculus
Gum recession
Fractured
give prednisolone for swelling & metacam for pain
What tooth is it and why is it discoloured? How can it be treated?
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Pulpitis
- damage to root causing bleeding in root
- haemoglobin enters dentine & stains
Root canal therapy (affected pulp removed & filled with suitable material - expensive)
Tooth removal
Crown or cap
Describe general antimicrobial (innate) factors in oral cavity
Describe specific antimicrobial (adaptive) factors in oral cavity
