5/26/2010Pathology of MinipigsBrett Saladino, DVM, Diplomate ACVPSwine as Lab Animals Similar physiology, metabolism and anatomy SkinGI tractHeartBrain KidneyMetabolismTeratogenicsensitivityConventional swine: Long history in pharmacology, surgical researchLimited use in toxicology due to sizeSwine vs Dogs EthicsNot prone to vomitingBetter NSAID toleranceTolerate sympathomimetic drugs better,no cardiotoxicityPhysiologically more similar to man1

5/26/2010Swine vs Primates EthicsLower costsEarly sexual maturity (3-6(3 6 months)High reproduction rateNo supply or conservation concernEasier to handle, transport, and houseFewer zoonotic diseasesMiniature Pigs Sus scrofa domesticaSmaller than 75 kg adult weight, easy tohandleRRequirei lless ffood,d lless ttestt materialt i lControlled geno- and phenotypeRegulatory acceptability (US, Japan, EU)Miniature Pigs Common miniature pig breeds used inresearch: Goettingen, Hanford, SinclairS-1, YucatanAvailable as SPF barrierbarrier-bred;bred; some arealso available as germ-freeLow background lesion incidence in mostbreeds2

5/26/2010Resources Bollen et al, The Laboratory Swine Svenson, The Minipig in Toxicology Swindle, Swine in the Laboratory Gad, Animal Models in Toxicology Hau & Van Hoosier, Handbook ofLaboratoryy Animal Science,, Vol. 3Goettingen Supplied by Marshall or EllegaardUsed extensively in EuropeWhite-skinned, short snout, pot belly6-mo weight 20 kgHanford Supplied by Sinclair Bio-resourcesLooks like a conventional pigWhite-skinned6-mo weight 40 kgSurgical and cardiovascular research Heart size, weightsimilar to humans Less subcutaneousfat than otherbreeds3

5/26/2010Sinclair SS--1 Supplied by Sinclair Bio-resources6-mo weight 25 kgDifferent colors; easy identificationUsed for cardiovascular, osteoporosis,diabetes and fetal alcohol syndrome researchdiabetes,Melanoma model lineYucatan Supplied by Sinclair Bio-resourcesOnly naturally occurring miniature pig; nativeto Southern Mexico & Costa RicaTwo distinct sizes available Minipig: 66-momo weight 30 kg Micropig: 6-mo weight 20 kgDarkly pigmented skin with little or no hairWhite skin line for dermal studiesSpontaneous ventricular septal defect lineDocile, easy to handleYucatanMinipigYucatanMicropig4

5/26/2010Housing US regulatory guidelines: Biomedical Research - Guide for Careand Use of Animals, 1996 Agriculturalg cu u a Researchesea c - GuGuidede foro theeCare and Use of Animals in AgriculturalResearch and Teaching, 1999No consensus on cage sizes or typesOften no dedicated facilities (flexibility!)Guide for Care and Use of Animals,National Academy of Science, 1996Number ofAnimalsWeight in kgFloor Area in m2 150.721Up to 251.082-5 5Up to 501.35Up to 1002.16 250.54Up to 500.9Up to 1001.8Up to 2003.6 250.54Up to 500.81Up to 1001.62Up to 2003.24Guide for Care and Use of AgriculturalAnimals in Agricultural Research, 1999Stage of ProductionIndividual pigsm2 per pigLitt andLitterd lactatingl t tisow, pen3.153 15Litter and lactating sow, sow portion1.26Groups of pigsm2 per pigNursery (3(3-27 kg of weight)0.540.37Growing (27(27-57 kg of weight)0.900.370.37--0.56Finishing (57(57-104 kg of weight)1.260.560.56--0.74Late finishing (105(105-125 kg of weight)1.260.740.74--0.84Mature adults1.261.495

5/26/2010Systemic PathologyFindingsMelanosis Pigmentation in internal organs – Normal inpigmented swineMeninges, lungs, spleen, heart valves, liver,lymph nodesNecrotizing Myositis GoettingenMultifocal skeletal muscle degenerationand necrosisMononuclear cell infiltratesMay see myocyte regeneration6

5/26/2010Mononuclear Cell Infiltrates Normal background findingSeen in many different organs: LiverAdAdrenall cortextGI tractLungHeart KidneyB iBrainPancreasSalivary glandsSkinMay indicate normal immune functionIntegumentary SystemSimilarities to Humans Lightly-pigmented, sparse hairThick epidermis Pig: 70-140 µmHuman: 5050-120120 µmRat: 10-20 µmEpidermal morphology and cell turnoverImmunologic reactivityDermal penetration of compounds7

5/26/2010Differences from Humans Ichthyoform; thick stratum corneumEccrine sweat glands limited to snoutand carpal areas (not involved inthermoregulation)Extensive subcuticular adiposeSkin pH of 6-7 compared to 5 in manPorcine juvenile pustular psoriasiformdermatitis (Pityriasis rosea) Young, whitewhite-skinned breedsCircular to serpiginous, erythematousl ilesionswithith crusts,t usuallyll on ventralt labdomen & inner thighsEtiology unknownTransient anorexia and diarrhea reportedSpontaneous resolution in 66-8 weeksPorcine juvenile pustular psoriasiformdermatitis (Pityriasis rosea) Microscopic lesions Early: perivascular eosinophilic andlymphoplasmacytic inflammation,spongiform pustules, & psoriasiformhyperplasia Later: Hyperplastic plaques with littleinflammation, ultimately resolve completely,leaving normal skin8

5/26/2010Cutaneous Melanoma Specific line of Sinclair S-1 pigs is a model formalignant melanoma 50% of piglets have tumors at birth, 85% by 6weeks of ageHereditary, not related to sun exposureMicroscopic features, pattern of metastasis verysimilar to humansSpontaneous depigmentation and regressionbetween 6-12 months of ageThrombocytopenic PurpuraSyndrome Goettingen pigletsImmune--mediated thrombocytopeniaImmune(platelets 20 20,000/ul)000/ul) and anemiaCutaneous purpuraDisseminated visceral hemorrhagesOthers ? Other cutaneous pig diseases are seen rarely ifever in laboratory minipigs Staph hyicus (greasy pig disease) Erysipelothrix rhusiopathiae (diamond skindisease) Parakeratosis (zinc(zinc--responsive dermatosis) Ringworm Dermatosis vegetans9

5/26/2010Respiratory SystemRespiratory Diseases Minipigs are genetically susceptible to allporcine respiratory diseasesActual disease rare in the lab setting SPF / barrier-raisedb ii d pigsi Vaccination HusbandryShould always perform completenecropsy on acute pigs to protectherd healthPorcine RespiratoryDisease Complex Primary pathogens M. hyopneumoniaeA. ppleuropneumoniaepSIVPRRSVPRVPRCVPCV Secondary pathogens P. multocidaS. suisH. parasuisB. bronchisepticaA. pyogenes**A. pleuropneumoniae10

5/26/2010Laryngeal traumaLong soft palate and laryngeal diverticulummake intubation or gavage difficultTraumatic procedures can cause edema /acute inflammation in the pharynx, larynx,and cervical region Alveolar Histiocytosis Increased numbers of foamy macrophagesin alveoliMay be grossly visible as white areas inlungCan be increased in gavage studies orstudies with amphiphilic compounds, butalso occur as a normal background findingin control pigsPulmonary IntravascularMacrophages (PIMs) Primary site of removal of blood-borneparticulates in pigs and ruminants.Similar function to the hepatic Kupffer celli dindogs, rodentsd t andd primates.i tPIMs are resident cells, junctionallyadherent to pulmonary capillaryendothelium.Be cautious using pigs for studies withinjectable microencapsulated compounds.11

5/26/2010Digestive SystemSimilarities to Humans OmnivorousLarge stomach, long small & large intestineGastric cell types and secretionsSmall intestinal transit timeDigestion, absorption, pH changesTooth developmentGastric ulcer syndrome Begins with hyperkeratosis of theesophagus and/or pars esophageaRelated to anorexia or finely ground,pelletedll t d ffeedd – decreaseddd gastrictiemptyingStomach acid damages the squamousepitheliumExacerbated by stress12

5/26/2010Cardiovascular SystemSimilarities to Humans Cardiovascular physiology, especiallystress-related responsesSimilar heart and great vesselsCoronary arterial blood supply No collateral vessels in myocardium Coronary artery can be clamped toinduce myocardial infarctPostprandial lipemiaArteritis Goettingen minipigsDegenerative vascular lesions in smallsmall- tomedium--sized muscular arteriesmediumCoronary arteries and vessels of the renalpelvis are most consistently involvedIntimal proliferation, medial thickening / /necrosis, endothelial proliferation, luminalstenosis, thrombosis, disruption andfragmentation of the internal elastic lamina13

5/26/2010Ventricular Septal Defect (VSD) Specific Yucatan mini- and micropiglines are models for VSDOccurs in about 20% of fetuses65% are high membranous defectsPolygenic defectVSD Small defects may close spontaneouslyLarge defects create L to R shuntsleading to pulmonary hypertension andrespiratory distressMay also cause a “failure“failure-to thrive”syndromeExcellent model for human diseaseUrinary System14

5/26/2010Interstitial Nephritis Goettingen and Sinclair SS -1Interstitial mononuclear cell infiltratesTubular degeneration and lossTubular ectasia and proteinosisBasement membrane thickeningGlomerulosclerosisFibrosisNervous SystemSimilarities to Humans CNS development; brain growth spurt beforebirthMajority of CNS cell division before birthMyelination largely postnatalBlood-brain barrier relatively immature at birthHighly developed eyeIdeal for teratology studies15

5/26/2010Retinal Dysplasia GoettingenFolds orrosettes in“rosettes”retinaCongenitalbackgroundlesion16