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Pathology of the alimentary system 1
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OutlineIntroduction
Post mortem examination of the alimentary systemPathology of the upper gastrointestinal tract
Oral cavityTeethSalivary glands and tonsilsTongueEsophagusStomach
Pathology of the lower gastrointestinal tractSmall and large intestine
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Outline (cont.)
Intestinal diseases of carnivores (dogs and cats)Bacterial enteritisViral enteritisParasitic diseasesOther
Intestinal diseases of pigsIntestinal diseases of ruminantsIntestinal diseases of horsesIntestinal neoplasiaPathology of the peritoneum
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References
Pathologic Basis of Veterinary Disease McGavin & Zachary (2007), 4th edition, chapter 7
Jubb, Kennedy and Palmer’s Pathology of Domestic AnimalsMaxie (2007), 5th edition, Vol.2, chapter 1
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IntroductionOral cavity
TeethTonsils Salivary glands Tongue
Esophagus StomachIntestines Peritoneum Liver and pancreas
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IntroductionAlimentary disorders are common in domestic animalsDisease manifestation varies according to species
Portals of entry of pathogensIngestion (most common)Coughed up by the lungs and swallowedSystemic circulation (bacteremia, viremia)Migration through the body (parasites)Migration through the body (parasites)
Spirocerca lupi- Dog’s aorta6
Defense mechanismsEndogenous secretions Resident flora and faunaGastric pHHigh rate of epithelial turnoverVomiting and peristalsis Innate and adaptive immune system
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Post mortem examination of the gastrointestinal tract
Sudden deathWastingHypoproteinemiaVomitingDiarrheaAnemiaSuspected septicemia
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Post mortem examination
Necropsy techniqueUse a systematic approachDetermine what is normal and what is abnormalOBSERVE!!!
Establishing an accurate etiologic diagnosis incases of gastrointestinal disease usually requires acombination of diagnostic testscombination of diagnostic tests
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Oral cavityDevelopmental anomaliesStomatitis and gingivitisHyperplastic and neoplastic lesionsDiseases of teethDiseases of tonsils and salivary glandsDiseases of the tongue
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Developmental anomalies
AgnathiaPalatoschisisCheiloschisisEpitheliogenesis imperfectaEpidermolysis bullosa
Epitheliogenesis imperfecta11
Palatoschisis
PathogenesisFailure of fusion of lateral palatine processesEtiology unknown
Genetic factors (Charolais cattle)Maternal ingestion of drugs (ie. griseofulvin inqueens and mares; steroid administration duringpregnancy in primates)Teratogenic plants (ie. lupines, hemlock in ewesand sows)
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Palatoschisis
Palatoschisis in a sheep
Palatoschisis in a calf13
Cheiloschisis
“Hare lip” in calves
Cheiloschisis
“Hare lip” in calves
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Stomatitis and GingivitisVesicular stomatitides
Characterized by the formation of vesicles(accumulation of serous fluid within theepithelium or between the epithelium andlamina propria)Infectious or non-infectious
Feline calicivirus- Oral vesicles 15
Feline calicivirus -vesicles in the tongue16
Vesicular stomatitidesFoot and Mouth Disease (FMD)
Picornavirus(Aphtovirus)
Ruminants, pigs
Vesicular Stomatitis (VS) Rhabdovirus(Vesiculovirus)
Cattle, pigs, horses
Vesicular Exanthema of Swine (VES)
Calicivirus Pigs
Swine Vesicular Disease (SVD)
Picornavirus(Enterovirus)
Pigs
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All virally inducedVery similar clinical, gross and histologic appearanceFluid-filled vesicles on lips, buccal mucosa, margins oftongue coalesce to form bullae bullae ruptureulcers
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• Lesions may arise on coronary bands, interdigital skin,teats, vulva
• Histologically start as intracellular edemaballooning degeneration of stratum spinosumnecrosis intercellular edema
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FMD, VES and SVD are exotic to the US andthus are reportable to state and federalauthorities
Foot and Mouth DiseaseOne of the most contagious animal diseases; importanteconomic lossesLow mortality rate in adults, often high mortality in youngdue to myocarditisVesicles or blisters on the tongue, dental pad, gums, cheek,hard and soft palate, lips, nostrils, muzzle, coronary bands,teats, udder, snout of pigs, and interdigital spaces
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Foot and Mouth Disease
Post-mortem lesions on rumen pillars, and in themyocardium particularly of young animals “tigerheart”
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Lesions can be more severe in pigs than in cattle
Foot and Mouth Disease
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Vesicular Stomatitis
Rhabdovirus (vesiculovirus)Common in calves, does not affect goats, sheep;affects horses and pigsInsects may act as vectorsLesions limited to the epithelial tissues of themouth, teats and feetLesions limited to the epithelial tissues of the
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Vesicular ExanthemaCalicivirusDisease of pigs; clinically andpathologically indistinguishablefrom FMDClosely related to San Miguelsea lion virus
Swine Vesicular DiseasePicornavirus (Enterovirus)Indistinguishable from otherswine vesicular diseases
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Non-infectious vesicular diseasesPemphigus vulgaris
Autoimmune disease mediated by autoantibodies tothe desmosome protein desmoglein 3Characterized by acantholysis
Bullous pemphigoidAutoimmune disease characterized by subepithelialclefting and no acantholysisclefting and no acantholysis
Pemphigus vulgaris
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Erosive/Ulcerative Stomatitides
Mechanisms
Viral damage to the epitheliumCompromised circulation to subepithelial connectivetissue resulting in infarction of the epitheliumMay reflect ulceration of vesicular stomatitides
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Erosive/Ulcerative Stomatitides
Agents responsible include:Viruses Bovine viral diarrhea virus (BVD), Rinderpest,Malignant catarrhal fever (MCF), Feline Calicivirus,Equine Viral Rhinopneumonitis, Bluetongue
Other causes:UremiaFeline Eosinophilic Granuloma ComplexVitamin C deficiency in primates and Guinea Pigs
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Bovine viral diarrheaBovine viral diarrhea
Ulcerative stomatitis BVD (mucosal disease)
Ulcerative gingivitis BVD
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Rinderpest
Malignant catarrhal fever
Blue tongue
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Non-infectious causes
Uremia
Feline eosinophilic granuloma(rodent ulcer)
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Uremic stomatitisPathogenesis
High blood and salivary urea oral bacteria transforms salivary urea into ammonia caustic injuryVascular damage thrombosis ischemia infarctionIncreased urea decreased immune response
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Papular/Proliferative Stomatitides
Caused by Parapoxviruses (both zoonotic)Viral infection of epithelial cells results in cell swelling and hyperplasia
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Bovine papular stomatitis
Papules on nares, muzzle, gingiva, buccal cavity, palate,tongue, esophagus, rumen and omasum
Characterized by ballooning degeneration of the stratumspinosum epithelial cells may contain eosinophilicintracytoplasmic parapoxvirus inclusions
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Contagious ecthymaAffects sheep and goatsMacules, papules, vesicles, pustules, scabs, scars,in areas of skin abrasions corners of mouth,mouth, udder, teats, coronary bands, anus,esophagus, rumenEpithelial cells may contain eosinophilicintracytoplasmic viral inclusions
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Necrotizing/Deep Stomatitides
Occur in cattle, sheep, pigsEpithelial trauma permits invasion of opportunisticallypathogenic normal flora into deeper tissues of the oralcavity (muscle, fascia, bone, and/or regional lymphnodes)
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Calf diphtheria (Oral necrobacillosis)
Usually end-stage of any form of stomatitis complicatedby infection with Fusobacterium necrophorum (Gram-negative anaerobe) produces necrotizing toxinsClinical signs swollen cheeks, anorexia, fever, fetidbreath
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Other stomatitides1. Oral eosinophilic granuloma
Presence of a focal granuloma or ulcer within the oralcavity of cats, less commonly young dogsCats upper lips (near commissure); may develop ingingiva, palate, pharynx, tongue, regional lymph nodesCanine eosinophilic granuloma young male SiberianHuskies, Cavalier King Charles SpanielHuskies, Cavalier King Charles Spaniel
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Oral eosinophilic granulomaAffected animals can have peripheral eosinophiliaCause unknown; suspected immune-mediatedmechanism hypersensitivity reaction ?Histologically, characterized by the presence ofmultiple eosinophilic granulomas around a centralfoci of collagenolysis
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2. Lymphoplasmacytic stomatitis
Chronic idiopathic condition of cats characterized byinflamed gingiva, inappetence, fetid breathAssociated with other infectious diseases (feline leukemiavirus, feline immunodeficiency virus)
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3. Chronic ulcerative paradental stomatitis
Condition of dogs also known as ulcerative stomatitis and lymphocytic-plasmacytic stomatitisMore common in older dogs and in Malteses and Cavalier King Charles SpanielsKing Charles Spaniels
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