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The integument’s viral diseases in horses
1.
Papillomatosis
Cattle type 1, 2 and horse papilloma virus
sarcoid: bpv1 enhanced lcr activity in horse cells
(long control region)
Pathogenesis: Virus  str germinat. cell proliferation,
but ceratinocytes contain the matured viruses
Clinical signs: 4-6 weeks
cauliflower like, warted, benign cell tumours:
exception; sarcoid bovine papillomav.
type specific protection
Diagnosis:
Macroscopic:
signs are characteristic
Histology:
ELMI, IF, PCR
AGID (indirect)
Differential diagnosis:
Epithelial and connective tissue tumours
Strangles
Glanders
Str. Equi (2)
abscessi
P. mallei
granulomas in skins,
erosions in nasal cavity,
respiratory signs
Dermatophylosis
D. congolensis
scurf
Lymphangitis
caused by Coryneb. Pseudotuberculosis
lymphangitis
Histoplasmosis (Histoplasma farciminosum)
lymphangitis
Papillomas caused by equine papillomavirus
Photo; R. Pascoe
Sarcoid caused by bovine
papilloma virus
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  local
multiplication  papulae  epithel degeneracy
 erosions  scurf  pigmented spots
prone to recovery
Diagnosis:
Virus isolation, PCR
Differential diagnosis:
Due to its characteristic clinical signs
and predilection’s sites can not be confused
with other diseases
Photo; T. Lane
Lesions due to coital exanthema virus
3.
Vesicular stomatitis
Rhabdoviridae, vesiculovirus, 2 serotypes: Indiana
New-Jersey
Only on the American continent, transmission by
insects, horses, ruminants, pigs, humans
Clinical signs: Vesiculae on the mucous membrane of the
oral 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-ELISA
mouse inoculation
indirect: CF, VNT, ELISA
Differential diagnosis: The only vesicular disease of horses
ruminants, 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 circulatoryand lymphatic system
African horse sickness
Arthropode borne = arbovirus infection in equidae (Culicoidae)
Reoviridae, Orbivirus 10 serotypes, varying virulence
Mosquitoes spread (real vector) warm, wet climate,
over 500 m does not exist
Pathogenesis: mosquito  skin 5-9 days incubation 
lymph.n. (5-10 days)  viraemia  vascular endothel
cell 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 fever
subacute:
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, IF
nucleic acid detection: RT-PCR
indirect:CF, AGID, ELISA
Differential diagnosis: (Oedema, haemorrhage)
Equine arteritis abortion, virus isolation, PCR
Equine 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; J. Hodgson
Large amount of froth
in peracut stage
Photo; A. Elmissery
Subacut oedematous
swelling
Equine infectious anaemia
world-wide spread, Retroviridae, Lentivirus genus
Epizootology:
lifelong carrier horses, arbovirus, short term carrier
vector
Pathogenesis:
Insects(Tabanidae,Stomoxys c.)viraemialymphoret. tiss;
lymph.n., liver, spleen, bone marrow  2-3 weeks fever
 anaemia, decreased rbc production  increasing
rbc lysis 
immune complexes  new antigen variant
 repeated viraemic fever  immune supression 
immune complex formation
Clinical signs: acute;
haemorrhages, oedema
chronic;recurrent fever, fatigue
Pathological findings:
anaemia
Sago palm like spleen: lymphoid cell proliferation,
mace like liver:
limphohistiocytic infiltration
pale kidneys:
glomerulonephritis
Diagnosis:
haematology
histopathology
isolation from leucocytes on leucocyte cell culture
nucleic acid detection: RT-PCR
indirect:Coggins test (AGP), ELISA
Differential diagnosis:
African horse sickness acute phase:
Equine arteritis
Anthrax
Babesiosis
Equine encephalitis
Petechiae on the mucous membrane
Photo; T. Lane
frothy nasal disch
abortion and respiratory dis.
carbunculus, Ascoli test
blood smear
cl. signs of the nervous system
Viral infectious diseases of the respiratory tract
Herpesviruses:
Equine abortion; EHV-1
World-wide spread, Alphaherpesvirinae, varicellovirus
Pathogenesis: Aerogen (peroral) nasopharyngeal muc.
membrane  blood-stream
leucocytes
 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, PCR
indirect:VN
Differential diagnosis: Respiratory, nervous s. forms, abortion
Rhinopneumonitis (EHV-4)
mouse pathogenicity, abortion rare,
IF Mab, PCR
foals EHV-2
in the first 3 month
foals EHV-5
between 3-9 month
adenovirus
between 2-4 month diarrhoea
(immune deficient Arabian thor.br.)
Reovirus
foals
Aphtho,-Erbovirus
acute, febrile resp.disease, RT-PCR
Equine arteritis
abortion, carrier stallion
Influenza virus
acute, febrile resp. diseas. e.egg inoc
HAI, RT-PCR
Paramyxoviruses
only in Far-East and Australia
Rabies
altered behaviour, Negri bodies
IF
Equine encephalit.
seasonal, human diseas. too e.egg.in
Bornavirus
endemic, epileptiform convulsions
Foals’ respiratory disease caused by EHV-2
World-wide spread, pathologically contentious
importance 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 month
Adenovirus
between 2-4 month diarrhoea
(immune deficient Arabian thor.br.)
Reovirus
foals
Aphtho-,Erbovirus
acute, febrile resp.diseas. RT-PCR
Influenza virus
acute, febrile resp.diseas. e.egg in.
HAI, RT-PCR, high morbidity
Rhinopneumonitis caused by EHV-4
World-wide spread, Alphaherpesvirinae, Varicellov.
endemic
Pathogenesis is the same like EHV-1 its virus variant
pneumotrop
Diagnosis:
Like in the case of EHV-1, mouse pathogenicity index
Differential diagnosis:
see EHV-1
Foals’ respiratory disease caused by EHV-5
lesser-known, endemic, Gammaherpesvirinae,
Rhadinovirus genus, between 3-9 month manifest
itself
Differential diagnosis:
like EHV-2
Adenovirus
Arabian thoroughbred frequent: combined immune
deficiency (CID) autosomal recessive transmittance
lack of functional T és B lymphocytes
secondary bacterial infection
Aphtho- and Erboviruses
3 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 month
Reovirus
foals
Herpesviruses see. herpes
Equine influenza
embr.egg propagation, HAI, RT-PCR
Respiratory disease caused by Reovirus
3 serotypes orthoreo 1, 2, 3, non species specific,
in early age, pneumoenteritis, bact. coo-infection
Diagnosis:
direct: virus isolation, HA, RT-PCR
indirect:HAI, VNT
Differential diagnosis:
Adenoviruses
Herpesviruses
Aphtho- and Erboviruses
Equine 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, abortions
Adeno-, }
Aphtho-, Erboviruses } lower morbidity, age
Reoviruses
}
Equine arteritis abortions, oedema, haemorrhages
Bacteria:
Streptococcuses
pustules, abscesses
Rhodococcus 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 positivity
indirect: CIEF, VNT
Differential diagnosis:
Toroviruses
infect in all life
Diarrhoea caused by Toroviruses
Nidovirales, coronaviridae, torovirus genus
Horse, ruminant, pig, cat, human, clinical signs are infrequent, stenoxen
Diagnosis:
direct: virus isolation, RT-PCR
indirect: ELISA
Differential diagnosis:
Rotavirus
young age, higher morbidity
Viral infectious diseases of the reproductive organs
Equine abortion (see at respiratory viral diseases)
Equine arteritis
World-wide spread, 1 serotype, different virulence,
virus carrier stallions, abortions
Pathogenesis:
Aerogen-peroral infection  macrophages 
viraemia  damage of the arteoli in all body  abortion
Venereal infection  muc.memb  reg.lymph.n.
viraemia  …
Clinical signs: Mainly inapparent, but could be acute and
chronic (stallion), fever, resp. signs, oedema,
gravid mares abortions
Diagnosis:
direct:
indirect:
Virus isolation, IF, IHC, RT-PCR
VNT, ELISA
Differential diagnosis:
1. Respiratory signs:
Herpesviruses
Equine influenza
Adeno-, Reo-, Aphto-, Erboviruses
bacteria: Rhodococcus, Malleus
2. Abortion:
Abortion by EHV-1(more frequent, no oedema)
bacterial abortions:
Staphylo-, Streptococcus
E. coli, Klebsiella
Salmonella abortusequi
Taylorella equigen (Chronic equine metr.)
Actinobacillus equli
Leptospirae
Chlamydophila psittaci
3. Oedema:
Eq.infect.anaemia, Afr.horse sickness, Babesia
pyosepticaemia
Viral Infectious diseases of the nervous system
Rabies
World-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) form
quiet rabies
excitation, colic, frequent urination, incurable
Diagnosis:
direct: IF, histology: Negri bodies, mice i.c.
inoculation
indirect: VNT, (FAVN, RFFIT)
Differential diagnosis:
EHV-1
Equine encephalitis
Borna disease
Tetanus
Botulisms
spinal chord paralysis, slowly
progrediating
vectors, seasonal, human
cases as well
endemic
tetanic, sawing-horse position,
anamnesis
atonic paralysis, anamnesis
Equine encephalitis:
Eastern (EEE), Western (WEE), Venezuelan (V
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 behaviour
Borna disease
Tetanus, Botulism
Flavivíruses caused encephalitis
Flaviviridae, Flavivirus
West-Nile virus
All over the world
Arbovirus – mosquitos, gnats
birds, mammalians, humans
Pathogenesis: Gnats  viraemia 
organs
neuroinvasive strains - encephalitis
Clinical signs: 2-4 weeks incubation period
incoordination, excitation, colic
Diagnosis:
direct:
indirect:
isolation, IHC, RT-PCR
VN, IgM ELISA, IF
Differential diagnosis:
EHV-1 :
Rabies:
EEE, WEE, VEE:
Borna disease:
Tetanus
Botulism
myelitis paralysis,
slow progrediation
behavioural change, labor
epidemiol., labor. exam.
localization, labor. exam.
West-Nile virus caused encephalitis (Üllő)
Borna disease
ELMI examination always negative, endemic, seropositivity
In other countries, horse, sheep, goat, cat, human,
Bornaviridae, Bornavirus genus, reservoir: shrew (Sorex…)
Pathogenesis: Grazing  aerogen spread  n. olfactorius
 brain, nerve-cells  slow degeneration
in the presence of antibodies
Incubation period 2 weeks with 90% lethality in horses
Clinical signs: digestive- and respiratory tract’s disorders,
Excitation, depression, salivation, apathy, spasmus
slowly progrediating poliomyelitis
In sheep "falling down" is characteristic
Diagnosis:
direct:
indirect:
virus isolation cell culture, IHC, RT-PCR
Westernblott, ELISA
Differential diagnosis:
EHV-1
Rabies
Equine encephalitis
Tetanus
Botulism
prone to cure
behaviour, IF, Negri
seasonality