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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