Zusammenfassung der Ressource
Pathology of the Alimentary Tract 1
(Oral Cavity & Oesophagus)
- Alimentary Tract
- Normal Histology (Alimentary Tract)
- Stratified Squamous epithelium
- Mouth
- Oesophagus
- Non-glandular part of
stomach: Pigs, Horses
- Forestomachs: Ruminants
- Anus:
- Keratinized: Ruminants,
Horses, Pigs
- Non- Keratinized:
Dogs & Cats
- Simple columnar glandular epithelium
- Stomach; Abomasum
- Surface epithelium
- Simple tubular glands
- Chief (peptic, zymogen) cells: Pepsinogen
- Parietal (oxyntic) cells: HCl
- Neuroendocrine cells
- Stem cells: Neck of gland
- Small intestine
- Progenitor cells: Crypts
- Enterocytes: Villi
- Mucous (goblet) cells
- Neuroendocrine cells
- Large Intestine
- Enterocytes: Crypts,
surface epithelium
- Mucous(goblet) cells
- Defense Mechanisms (Alimentary Tract)
- GI tract sterile at birth ->
becomes colonized w/ bacteria
- Routes of Entry:
- Oral ingestion
- Secretions swallowed
from the respiratory tract
- Haematogenous dissemination
- Parasite migration
- Secretions
- Saliva
- Mucous
- Inhibits contact w/ mucosa,
protects surface
- Acid
- Parietal cells in stomach
- Digestive enzymes
- Salivary amylase, Pepsin from
gastric chief cells, pancreatic & SI
enzymes
- Bile secretions
- Kill some pathogens
- Flushing effect & antibacterial
components (Ex. lysozyme,
secretory IgA)
- Epithelium
- Mucosal barrier
- Stomach, Intestine
- Tight junctions (b/w
epithelial cells)
- Prevent entry of
macromolecules &
pathogens (but
allows ions & H2O to
diffuse through)
- Very high cell turnover
- Stratified Squamous
epithelium
- Oral cavity
- Multilayered
- Relatively high
cell turnover
- Keratinized surface
layer at some sites
- Commensal Flora
- Act as barrier to
pathogens
- Secrete VFAs &
compete w/ pathogens
for nutrients
- Essential for digestion
in herbivores
- Any disequilibrium
of microflora can
lead to disease
- Movement
- Continuous movement/peristalsis
discourages persistence of insult/agent
- Cell-mediated & Humoral Defenses
- Lamina propria:
- Macrophages, B & T
Lymphocytes, Plasma cells,
mast cells
- Epithelium:
- Intraepithelial lymphocytes
(T lymphocytes)
- Lymphoid Aggregates:
- Peyer's Patches (esp. ileum), GALT
- Ab production (esp. secretory IgA)
- Regional Lymph Nodes
- Omental macrophages
- Inflammation in the Alimentary Tract
- Vascular changes
- Hyperaemia (Congestion)
- Reddening, Oedema
- Haemorrhage: Petechiae, Ecchymoses
- Exudates
- Serous/Mucous/Seromucous: Catarrhal
- Suppurative (Purulent)
- Mucopurulent
- Diptheritic: Fibrin & Necrotic material,
secondary bactrerial invasion
- Oral Cavity
- Defense Mechanisms (Oral Cavity):
- Taste buds
- Normal bacterial flora
- Saliva (flushing, coating,
lysozyme & Igs)
- Developmental Anomalies
(Oral Cavity)
- Brachygnathia superior/inferior
- Short maxilla/mandible
- Prognathia
- Abnormal prolongation
of maxilla/mandible
- Cleft palate/palatoschisis
- Inadequate growth of palatine
shelves leaves a central defect
- Communication of nasal &
oral cavities may result in
aspiration pneumonia &
problems w/ suckling
- Affects hard &/or soft palate
- Hare lip/cheiloschisis
- Absence of part of lip
rostral to nasal septum
- Inflammatory Lesions (Oral Cavity)
- Inflammation predominates in
Chronic lesions of bacterial or
fungal origin
- Granulomatous inflammation
- Actinobacillosis ("Wooden togue")
- Actinobacillus
lignieresii
- Actinomycosis ("Lumpy jaw")
- Actinomyces bovis
- Mandible becomes enlarged
due to chronic osteomyelitis
- Eosinophilic Inflammation
- Oral eosinophilic
granuloma (Cats)
- Necrotizing Inflammation
- Calf diptheria
- Fusobacterium necrophorum
- Coagulative necrosis &
surrounding granulation tissue
affecting the gingival & oral mucosa
- Vesicular Inflammation
- Often viral
- Vesicular, ulcerative or
proliferative patterns may also
co-exist or progress (e.g. vesicles
-> ulcers)
- Foot & mouth disease
- Feline calcivirus
- Erosive Inflammation
- Ulcers may progress from vesicles, but
can also be caused by: some bacterial
& immune-mediated diseases, trauma
- Feline calcivirus &
Feline herpesvirus
- Causes mouth ulceration
- Mucosal Disease
- Bovine viral diarrhoea virus (BVDV)
- Causes ulceration of oral cavity, muzzle
& more distal alimentary ytact
- Immune - mediated diseases
- Autoantibodies directed against
epithelial cell surface Ags
- Ex. Pemphigus vulgaris, bullous
pemphigold (Dogs, Cats & Horses)
- Papular Inflammation
- Proliferative (papular) lesions
- Contagious pustular
dermatitis ("orf")
- Firm, raised papules &
pustules on lips & oral mucosa
- Sheep & Goats
- Hydrophobic degeneration, mixed
inflammatory cell infiltration &
secondary bacterial invasion
- Neoplasia (Oral Cavity)
- Epithelial Tumors
- Papillomas
- Benign
- Raised, sometimes
cauliflower-like lesions (Lips
& Oral Mucosa)
- Thick squamous epithelium
over a branching
pedunculated fibrous stroma
- Squamous cell carcinoma
- Malignant
- Most common oral
malignancy (Cats)
- Ventrolateral tongue
- Locally invasive +/- metastases
- Composed of elevated firm,
white plaques or nodules that
may ulcerate
- Irregular masses & cords of
squamous epithelium invading
the lamina propria
- May be circular pearls of keratin
- Melanoma
- Tumor of pigment
producing melanocytes
- Most common oral
neoplasm (Dog)
- Nearly always
Malignant (in oral
cavity)
- Grow rapidly & are
not always pigmented
- Oval or spindle-shaped
melanocytes w/ variable
melanin content
- Epulis
- Group of benign
neoplasms of peridontal
origin affecting gingivae
- Particularly in
brachycephalic Dog
breeds (boxer)
- Firm lesions on gums,
surrounding teeth, esp.
carnassial/canine region
- Dense collagenous & sometimes
ossified tissue covered with stratified
squamous epithelium (descends into
dermis in cords)
- Oesophagus
- Congenital Anomalies
- Segmental aplasia
- Rare failure of fusion
- Band of fibrous tissue where
distal oesophagus should be
- Achalasia
- Failure of cardiac
sphincter to open
- Functional (Neuromuscular) Disorders
- Megaesophagus
- Dilated oesophagus lacks peristalsis
- Accumulates ingesta due to underlying
neuromuscular disorder (or obstruction),
but lower oesophageal sphincter is usually
normal
- Aspiration pneumonia may be a sequel
- Idiopathic
- Developmental disorder of vagus
nerve/motor nucleus (esp. Great Dane,
German shepherd, Siamese cat)
- Acquired
- Neurological
- Dysautonomias (ex.
Equine grass sickness,
feline dysautonomia),
Myaesthenia gravis
- Muscular
- Myodegeneration (ex.
nutritional myopathy (Vit.
E/ selenium deficiency in
cattle)
- Obstruction
- Intraluminal
- Foreign bodies ("Choke")
- Ex. Root vegetable, sugar beet pulp, bone
- Most likely sites are narrow
areas: Thoracic inlet, base of
heart & cardiac sphincter
- May cause inflammation, pressure
necrosis, ulceration & perforation
- Obstruction of Ruminant
oesophagus may cause
bloat
- Healing may cause
narrowing (Stricture)
- Intramural (w/in wall of
oesophagus)
- Inflammatory lesion (abscess,
granulation tissue), fibrosis or
neoplasm => Narrowing
- Extrinsic ( outside the
oesophagus)
- Vascular ring anomaly (persistent
RT. aortic arch constricts
oesophagus & leads to
megaoesophagus cranially)
- Also pressure from abscess,
haematoma, neoplasm
- Inflammation (Oesophagitis)
- Reflux Oesophagitis
- Damage from gastric acid
due to gastric-oesophageal
reflux or vomiting
- => Erosion of epithelium (may
progress to ulcers)
- Infectious Agents
- Ex. Actinobacillosis,
feline calcivirus
- Neoplasia
- Papillomatosis
- Cattle: Bovine papillomavirus
type 4 (transforms squamous
cell carcinoma w/ bracken fern
toxins)
- Squamous cell carcinoma
- Cats
- Leiomyoma
- Benign tumor of
smooth muscle