The integument’s viral diseases in horses

1. Papillomatosis

Cattle type 1, 2 and horse papilloma virussarcoid: bpv1 enhanced lcr activity in horse cells

(long control region)Pathogenesis: Virus str germinat. cell proliferation,

but ceratinocytes contain the matured virusesClinical signs: 4-6 weeks

cauliflower like, warted, benign cell tumours: exception; sarcoid bovine papillomav.type specific protection

Diagnosis: Macroscopic: signs are characteristicHistology:ELMI, IF, PCRAGID (indirect)

Differential diagnosis:

Epithelial and connective tissue tumours

Strangles Str. Equi (2) abscessiGlanders P. mallei

granulomas in skins, erosions in nasal cavity,respiratory signs

Dermatophylosis D. congolensisscurf

Lymphangitis caused by Coryneb. Pseudotuberculosislymphangitis

Histoplasmosis (Histoplasma farciminosum)lymphangitis

Sarcoid caused by bovinepapilloma virus

Photo; R. Pascoe

Papillomas caused by equine papillomavirus

2. Coital exanthema

Alpha herpesvirus, EHV-3, strictly species specific,world-wide spread

Pathogenesis: Venereal spread (sometimes on the udder)mucous membrane of vagina, glans localmultiplication papulae epithel degeneracy erosions scurf pigmented spotsprone to recovery

Diagnosis: Virus isolation, PCRDifferential diagnosis:

Due to its characteristic clinical signsand predilection’s sites can not be confusedwith other diseases

Lesions due to coital exanthema virus

Photo; T. Lane

3. Vesicular stomatitis

Rhabdoviridae, vesiculovirus, 2 serotypes: Indiana New-Jersey

Only on the American continent, transmission byinsects, horses, ruminants, pigs, humans

Clinical signs: Vesiculae on the mucous membrane of theoral cavity, on the skin, cushion, udder.Morbidity 10-15%, Mortality 0%

Diagnosis:direct: virusisolation cell culture VERO, BHK-21,giant cell formation, embr. egg, CF, IF, IS-ELISAmouse inoculationindirect: CF, VNT, ELISA

Differential diagnosis: The only vesicular disease of horsesruminants, pigs: FMD, SVD, VES, Stomatitis papulosa

Photo: B. Wright

Slobbers, due to vesicles in oral cavity

Erosions on the joint

Viral infectious diseases of the blood circulatory-and lymphatic system

African horse sickness

Arthropode borne = arbovirus infection in equidae (Culicoidae)Reoviridae, Orbivirus 10 serotypes, varying virulenceMosquitoes spread (real vector) warm, wet climate,

over 500 m does not existPathogenesis: mosquito skin 5-9 days incubation

lymph.n. (5-10 days) viraemia vascular endothelcell degeneration vasculituis thrombosis oedema, haemorrhages lung and heart insufficiency perishing 3-5 d.PI

Clinical signs: Mortality 50-90%peracute: frothy nasal discharge, 41°C feversubacute: haemorrhages, oedema in connect. tiss.

and sublingual, fever

Diagnosis:clinical signs, pathol. findings (fibrin, oedema)labordiagn.direct: Virus isolation: Cef, mouse i.c.

a.g. detection from leucocytes: ELISA, IFnucleic acid detection: RT-PCR

indirect:CF, AGID, ELISADifferential diagnosis: (Oedema, haemorrhage)

Equine arteritis abortion, virus isolation, PCREquine infectious anaemia: lymphoid cell prolif spleen,

interstitial lymphocytic infiltration of liver Coggins test

Anthrax dark blood, carbunculus, splenomegalia bacter and (Ascoli test)

Babesiosis haemocytological findings

Photo; A. Elmissery

Subacut oedematousswelling

Large amount of frothin peracut stage

Photo; J. Hodgson

Equine infectious anaemiaworld-wide spread, Retroviridae, Lentivirus genus

Epizootology:lifelong carrier horses, arbovirus, short term carriervector

Pathogenesis:Insects(Tabanidae,Stomoxys c.)viraemialymphoret. tiss;lymph.n., liver, spleen, bone marrow 2-3 weeks fever

anaemia, decreased rbc production increasingrbc lysis immune complexes new antigen variant repeated viraemic fever immune supression immune complex formation

Clinical signs: acute; haemorrhages, oedemachronic;recurrent fever, fatigue

Pathological findings: anaemiaSago palm like spleen: lymphoid cell proliferation,mace like liver: limphohistiocytic infiltrationpale kidneys: glomerulonephritis

Diagnosis:haematologyhistopathologyisolation from leucocytes on leucocyte cell culture nucleic acid detection: RT-PCRindirect:Coggins test (AGP), ELISA

Differential diagnosis:African horse sickness acute phase: frothy nasal dischEquine arteritis abortion and respiratory dis.Anthrax carbunculus, Ascoli testBabesiosis blood smearEquine encephalitis cl. signs of the nervous system

Petechiae on the mucous membrane

Photo; T. Lane

Viral infectious diseases of the respiratory tract

Herpesviruses:Equine abortion; EHV-1World-wide spread, Alphaherpesvirinae, varicellovirusPathogenesis: Aerogen (peroral) nasopharyngeal muc.

membrane blood-streamleucocytes lung bronchopneumonia uterus foetus lung, liver abortion nervous system inflammation of the arterioli

degeneration of the nerve-cells paralysis of hind limbs, incoordination latency

Diagnosis:direct: virus isolation, IF, IHC, PCRindirect:VN

Differential diagnosis: Respiratory, nervous s. forms, abortionRhinopneumonitis (EHV-4)

mouse pathogenicity, abortion rare,IF Mab, PCR

foals EHV-2 in the first 3 monthfoals EHV-5 between 3-9 monthadenovirus between 2-4 month diarrhoea

(immune deficient Arabian thor.br.)Reovirus foalsAphtho,-Erbovirus acute, febrile resp.disease, RT-PCREquine arteritis abortion, carrier stallionInfluenza virus acute, febrile resp. diseas. e.egg inoc

HAI, RT-PCRParamyxoviruses only in Far-East and AustraliaRabies altered behaviour, Negri bodies

IFEquine encephalit. seasonal, human diseas. too e.egg.inBornavirus endemic, epileptiform convulsions

Foals’ respiratory disease caused by EHV-2World-wide spread, pathologically contentiousimportance Gammaherpesvirinae, endemic, latency

Pathogenesis:dust aerogen lung, alv. macrophage epithel c.degeneration entry for Rhodococcus. equi

Diagnosis:from leucocytes cocultivation virus isolation, from nasal discharge virus isolation, PCR

Differential diagnosis:EHV-5 between 3-9 monthAdenovirus between 2-4 month diarrhoea

(immune deficient Arabian thor.br.)Reovirus foalsAphtho-,Erbovirus acute, febrile resp.diseas. RT-PCRInfluenza virus acute, febrile resp.diseas. e.egg in.

HAI, RT-PCR, high morbidity

Rhinopneumonitis caused by EHV-4World-wide spread, Alphaherpesvirinae, Varicellov.endemic

Pathogenesis is the same like EHV-1 its virus variantpneumotrop

Diagnosis:Like in the case of EHV-1, mouse pathogenicity index

Differential diagnosis:see EHV-1

Foals’ respiratory disease caused by EHV-5lesser-known, endemic, Gammaherpesvirinae,Rhadinovirus genus, between 3-9 month manifestitself

Differential diagnosis:like EHV-2

AdenovirusArabian thoroughbred frequent: combined immunedeficiency (CID) autosomal recessive transmittancelack of functional T és B lymphocytessecondary bacterial infection

Aphtho- and Erboviruses3 serotypes (1, 2, 3) in young horses (2 years)Serotype 1 related with FMDV, fever, nasal discharge,cough, sore throat.

Diagnosis:direct: virus isolation (serotype 1 broad cell spectrum)indirect: CF, VNT

Differential diagnosis:Adenovirus diarrhoea too, between 2-4 monthReovirus foalsHerpesviruses see. herpesEquine influenza embr.egg propagation, HAI, RT-PCR

Respiratory disease caused by Reovirus3 serotypes orthoreo 1, 2, 3, non species specific,in early age, pneumoenteritis, bact. coo-infection

Diagnosis:direct: virus isolation, HA, RT-PCRindirect:HAI, VNT

Differential diagnosis:AdenovirusesHerpesvirusesAphtho- and ErbovirusesEquine influenza viruses

Equine influenza

World-wide spread, Orthomyxoviridae, Influenzavirus 2 types:H7N7 (Prague)H3N8 (Miami) more severe form

Susceptible horses~100% diseased, but quick recovery

Pathogenesis: Aerogen infection nasal muc.membrane viraemia lung bact. complication

Clinical signs: Fever, respiratory symptoms, decline,inappetance

Diagnosis: direct: Virus isolation in e.egg, HA, IF, a.g. ELISA, RT-PCR

indirect:HAI

Differential diagnosis: epizootiology, clinical signs,

Herpesviruses lower morbidity, abortionsAdeno-, }Aphtho-, Erboviruses } lower morbidity, ageReoviruses } Equine arteritis abortions, oedema, haemorrhagesBacteria:

Streptococcuses pustules, abscessesRhodococcus equi lung abscesses

Viral infectious diseases of digestive tract of horses

Diarrhoea caused by Rotavirus

Young foals, in their first some weeks, lack of hygiene,A-G groups, all animal pathogens, most prevalent; A,nsp4 enterotoxin like effect

Clinical signs:diarrhoea, inappetance, exiccosis

Diagnosis:direct: virus isol. difficult, IF, ELMI, SDS-PAGE, RT-PCR

CIEF out-dated false positivityindirect: CIEF, VNT

Differential diagnosis:Toroviruses infect in all life

Diarrhoea caused by Toroviruses

Nidovirales, coronaviridae, torovirus genusHorse, ruminant, pig, cat, human, clinical signs are infrequent, stenoxen

Diagnosis:direct: virus isolation, RT-PCRindirect: ELISA

Differential diagnosis:Rotavirus young age, higher morbidity

Viral infectious diseases of the reproductive organs Equine abortion (see at respiratory viral diseases)

Equine arteritisWorld-wide spread, 1 serotype, different virulence, virus carrier stallions, abortionsPathogenesis:

Aerogen-peroral infection macrophages viraemia damage of the arteoli in all body abortionVenereal infection muc.memb reg.lymph.n.viraemia …

Clinical signs: Mainly inapparent, but could be acute andchronic (stallion), fever, resp. signs, oedema,gravid mares abortions

Diagnosis: direct: Virus isolation, IF, IHC, RT-PCR indirect: VNT, ELISA

Differential diagnosis:1. Respiratory signs:

HerpesvirusesEquine influenzaAdeno-, Reo-, Aphto-, Erbovirusesbacteria: Rhodococcus, Malleus

2. Abortion:Abortion by EHV-1(more frequent, no oedema)bacterial abortions:

Staphylo-, StreptococcusE. coli, KlebsiellaSalmonella abortusequiTaylorella equigen (Chronic equine metr.)Actinobacillus equliLeptospiraeChlamydophila psittaci

3. Oedema:Eq.infect.anaemia, Afr.horse sickness, Babesiapyosepticaemia

Viral Infectious diseases of the nervous systemRabiesWorld-wide spread, Rhabdoviridae, Lyssavirus genus

5 genotypes 4; bats! 1; foxes sylvatic form

Pathogenesis:bite muscle cells myoneural junction alongside neurones spinal chord brain change of behaviour brain nerve bundle paralysis

Clinical signs: incubation 2-8 weeks, rabid (frantic) formquiet rabies

excitation, colic, frequent urination, incurable

Diagnosis:direct: IF, histology: Negri bodies, mice i.c.

inoculationindirect: VNT, (FAVN, RFFIT)

Differential diagnosis:EHV-1 spinal chord paralysis, slowly

progrediatingEquine encephalitis vectors, seasonal, human

cases as wellBorna disease endemicTetanus tetanic, sawing-horse position,

anamnesisBotulisms atonic paralysis, anamnesis

Equine encephalitis: Eastern (EEE), Western (WEE), Venezuelan (VEE):Togaviridae, Alphavirus genus

Only in America, arboviruses, real vectors in spread,seasonal, rezervoir specieses: wild birds, (rodents),eurixen viruses: poultry, humans, high mortality!

Clinical signs: Fever, hyperestesy, gnashing, hyperactivity

Diagnosis: direct: virus isolation: mice i.c., e.egg, cell cult.indirect: CF, HAI, VN

Differential diagnosis:Getah v.Flavivirus enceph: West Nile v. St Luis-, Japan enc.

only labor. examin can be distingv.Rabies changed behaviourBorna diseaseTetanus, Botulism

Flavivíruses caused encephalitisFlaviviridae, Flavivirus

West-Nile virusAll over the worldArbovirus – mosquitos, gnatsbirds, mammalians, humans

Pathogenesis: Gnats viraemia organsneuroinvasive strains - encephalitis

Clinical signs: 2-4 weeks incubation periodincoordination, excitation, colic

Diagnosis:direct: isolation, IHC, RT-PCRindirect: VN, IgM ELISA, IF

Differential diagnosis:EHV-1 : myelitis paralysis,

slow progrediationRabies: behavioural change, laborEEE, WEE, VEE: epidemiol., labor. exam.Borna disease: localization, labor. exam.

TetanusBotulism

West-Nile virus caused encephalitis (Üllő)

Borna disease

ELMI examination always negative, endemic, seropositivityIn other countries, horse, sheep, goat, cat, human,Bornaviridae, Bornavirus genus, reservoir: shrew (Sorex…)

Pathogenesis: Grazing aerogen spread n. olfactorius brain, nerve-cells slow degenerationin the presence of antibodies

Incubation period 2 weeks with 90% lethality in horsesClinical signs: digestive- and respiratory tract’s disorders,

Excitation, depression, salivation, apathy, spasmusslowly progrediating poliomyelitisIn sheep "falling down" is characteristic

Diagnosis: direct: virus isolation cell culture, IHC, RT-PCRindirect: Westernblott, ELISA

Differential diagnosis:EHV-1 prone to cureRabies behaviour, IF, NegriEquine encephalitis seasonalityTetanusBotulism