Equine Emerging Diseases Flashcards
What are the main APHA Equien Notifiable diseases?
- African Horse Sickness
- Anthrax
- Contagious Equine Metritis
- Equine Viral Arteritis
- Equine Viral Encephalomyelitis
- glanders and Farcy
- Rabies
- West Nile Fever
What are the emerging diseases?
- Equine Influenza
- Piroplasmosis
- Equine Herpevirus 1
What to tell APHA if you suspect any of theses?
- Phone number, name and address of owner/premises
- Your contact details
- Location fo suspected animla
- N° of naimals affected
- Clinical signs observed - Details of recent animal movements
& STAY ON PREMISES
What is African Horse Sickness?
- Viral - Genus Orbivirus
- 9 distinct serotypes
- Relatively heat stable
How is AHS transmitted?
» Transmitted by Culicoides midges (Culicoides. imicola (principle
vector) and Culicoides. bolitinos);
- also occasionally mosquitoes (culex, anopheles, aedes), ticks
(Hyalomma, rhipicephalus) and biting flies (stomoxys and tabanus) - Iatrogenic – needles, dental and obstetric equipment
What seasonal factors to AHS?
Seasonal epiootic cyclical incidence - dx is seen in areas of dourght after heavy rainfall causing +++vectors
Also wind dispersal of vectors (700KM water, 150km land)
Where is the source fo the virus found?
– viscera and blood of infected horses, semen, urine, and nearly all secretions during viraemia phase
How long does viraemia last?
Viraemia usually lasts 4-8 days up to 21
days (40 days in zebras)
Do recovered animals remain carriers?
NO
Who are subclin reservoirs fo it? what si the mortality in who?
Zebras
Horses most severely afefcted with up to 95% mortality
+How can we diagnose AHS?
Based on CS (4 distinct forms), VI, RT-PCR, ELISA, PM
Describe signs in the Subacute Cardiac form of dx?
What signs in the peracute pulmonary form?
What signs in the mixed (acute) type?
What signs in suclin form of HSF?
What DDX for AHF?
- Anthrax * EIA * EVA * Trypanosomiasis * Equine encephalosis * Piroplasmosis * Purpura haemorrhagica * Hendra virus
TX & Prevention for AHS?
» There is no treatment available –
euthanasia is often chosen due to animal
welfare
» Prevention comes down to control of the vector – spraying, housing at dawn and dusk, insect repellants
» Vaccines are available in endemic regions – implications to trade/movement
T/F Thailand had its first outbreak in 2020?
True
Have we ever had AHF in UK?
NO
Describe West Nile Virus
» Virus; Flavivirus (related to Yellow Fever and Japanese Encephalitis)
» Vector borne – mosquitoes (Culex)
Who are amplyfyig hosts of West nile?
: birds – rarely show
CS’s (crows most susceptible)
What kind of hosts are horses and humans ?
dead end hosts - rarely develop enough virus to spread it
CS incidence with WNV?
MOSTLY Subclin; 10% go on to show CLS; 30 % mortality in those who do
What are the signs seen in WNV?
Neurological encephalitis and meningitis disease:
pyrexia, loss of appetite, depression, stumbling,
muscle twitching, partial paralysis, impaired vision,
head pressing, teeth grinding, aimless wandering,
convulsions, circling, inability to swallow, weakness
of HLs, paralysis, coma and death
What DDX for West niel virus?
- Other diseases causing neurological
encephalitis/meningitis - Rabies * EHV 1
How to Diagnose WNV?
- CS’s * ELISA serology for antibody
Tx for WNV?
no specific tx - supportive -> IVFFT, NSAID, steroids
Prevention?
Prevention: * Control of mosquitos * Vaccination of horses in endemic areas * Wild bird surveillance programmes * Reporting of crow deaths
What is Equine Prioplasmosis?
» Intercellular parasite
(apicomplexans) * Babesia caballi; Theileria equi
» Tick borne
– Dermacentor, Rhipicephalus, Hyalomma
What distribution of equine piroplasmosis
Worldwide distribution
* Europe, C/E Asia, Africa,
Cuba, S/C America, USA
* UK/Ireland currently disease-free
* No compulsory screening UK
* Risk of importing
What pathoG of equine piroplasmosis?
Sporozoites invades RBCs and WBCs -> haemolysis
Who does prioplasmosis affect?
Horses, mules, donkeys and zebra (camels?)
What are the 4 forms of clinical signs we may see with piroplasmosis?
- PEracute form (rare) - foudn dead
- Acute form - most common
- Subacute form - similar to acute
- Chronic form -> non specific CS
What specific CLs in Acute form ?
- fever (>40oC); reduced appetite, increased respiratory rate,
increased heart rate, congested mm, dark red urine, small/dry
faecal balls, unthrifty, anaemia, icterus
What specific signs with subacute form?
plus weight loss, mm vary from very pale pink to pale yellow/bright yellow, petechiae/ecchymoses on mm
Incubation period for PiroP?
T. equi 12-19 days; B. caballi 10-30 days
Differentials for PiroP?
- Surra (Trypanosoma evansi)
- EIA
- Dourine (Trypanosoma equiperdum)
- AHS
- Purpura haemorrhagica
- Plant and chemical toxicity
- Acute haemorrhage
Diagnosis fo PiroP?
- CS’s
- Blood smear during acute phase of disease
- Serology (ELISA, CF, IFAT)
How is piroP introduced to new area?
Via carrier or infected animal -> MOVEMENT
How can we Control PiroP?
- Consider serological test by ELISA or IFAT
- Reduce exposure to ticks (acaricides, eradication fo ticks, removing vegetation)
- Any EP pos animal should be quarantined / isolated
Tx for EP?
» No medical treatment is available currently – supportive care
» Antiprotozoal agents only temporarily clear T.equi from carriers
What is Equine Viral Arteritis?
» Equine arteritis virus
» Genus Arterivirus, family Arteriviridae
» Host range = Equids
» Some limited evidence that hosts may include camelids
What system does EVA affect and how?
» Vascular disease – widespread vasculitis, primarily of smaller arterioles
and venules – causes the oedema, congestion and haemorrhages,
especially in the subcutis of the limbs and abdomen, and excess peritoneal, pericardial and pleural fluid
- Pulmonary oedema, emphysema and interstitial pneumonia, enteritis and
splenic infarct have been seen in fatal cases of EVA in young foals
incidence of EVA?
» Increase in incidence of EVA in recent years – linked with increase horse
movement and use of transported semen
Transmission of EVA?
– respiratory, venereal (natural cover, AI) and congenital routes in late pregnancy
What kind of infecitons do we see with EVA?
Majority Subclinical
- Certain strains cause varying severity
What is typcial presentation of EVA?
- Fever, depression, anorexia, leukopenia, dependent oedema (esp. limbs, scrotum and prepuce),
conjunctivitis, ocular discharge, peri-orbital oedema, rhinitis, nasal discharge, urticaria, stillbirths, temporary
subfertility in stallions - Rare but in foals – pneumonia, enteritis or both
Recovery from EVA?
» Most infected equids make a complete recovery (regardless of severity of CS’s)
» Rarely fatal (except in very young foals)
» Long term carrier state can occur in stallions only – shedding virus in semen
Diagnosis of EVA?
Ddx for EVA?
- Equine influenza
- EHV1 and 4
- Streptococcal infections
(strangles and purpura
haemorrhagica) - Equine adenoviruses
- EIA
- AHS
- Hendra virus
Tx for EVA?
» Treatment: Supportive care
during the acute phase of
infection
» VACCINATION (Artervac EVA)
– currently unavailable
How many serotypes of EHV are there- what are the common ones?
» 9 serotypes of EHV, 1 and 4 are most common – young horses
* EHV-1 – respiratory disease, abortion, and neurological disease (Equine herpes
myeloencephalopathy EHM)
* EHV-4 – respiratory disease (occ. Abortion/neurological disease)
* Occasionally see fatal neonatal disease as a result of in utero infection
* Asymptomatic infection common – facilitates transmission
T/F EHV is enzootic in all countries in which have large horse populations?
True
Transmission of EHV?
via nose-to-nose contact in respiratory secretions; aerosol, aborted
tissues/placental fluid and via fomite transfer (up to 5 meters)
Herpes - does infection og away?
» Herpesvirus and therefore has the ability to become latent and reactivate under times of stress - older horses often transmit the virus, disease in weaned foals and yearlings (autumn and winter)@
What three systems affecte by EHV?
- Abortion
- Respiratory
- Neurological
Describe abortion?
- Late pregnancy (7+months), usually no other signs
Describe Respiratory distress?
- Pyrexia * Inappetance * Depression, dull, lethargic * Coughing * Nasal Discharge * LN enlargement (submandibular/retropharyngeal) * Conjunctivitis
Describe neuro dx?
- Pyrexia * Incoordination of the hind (and occasionally fore) limbs * Bladder weakness - distension, atony – urine retention/dribbling * Penile protrusion * Reduced tail/anal tone * Recumbency (inability to rise)
When are CS seen with EHV 1?
within 10 days of contact with infected horse
Diagnosis of EHV1?
Nasal swab, heparin/EDTA blood
sample for EHV serology, PCR, Virus isolation
Management of EHV?
» Isolate suspected cases
» Instigate biosecurity measures *
» No validated specific anti-equine herpes viral treatments are currently available.
Supportive/symptomatic treatment
» Good stud management and vaccination of all horses against EHV-1 and EHV-4 is recommended as a general principle
Why should we be careful when vaccinating in outbreak?
may inc chances of neuro clinical signs
Describe Contegious Equine Metritis
- Highly contagious
- Taylorella Equigenetalis - notifiable (Kelbsiella pneumoniae, Pseudomonas = not notifiable)
How is CEM transmitted?
- Direct
– natural mating or teasing - Indirect
– teasing, via equipment/handling, AI
(contaminated semen)
Presentation of CEM in stallions?
show no CS’s, carriers of the organism on
prepuce, surface of penis and urethral opening (occasionally can invade stallions sex glands – pus and bacterial contamination of semen)
MAre presentation of CEM?
– vaginal discharge (ranges from very mild to profuse)
– can also have a carrier state (can transmit bacteria from clitoris, clitoral fossa and sinuses)
Diagnosis. ofCEM in MAres?
Clitoral swab – from clitoral fossa and clitoral sinuses
– mini tip swab
Endometrial swab – during oestrus
CEM diagnosis in Stallions?
Stallions:
Swabs from urethra, urethral
fossa, and penile sheath
– separate swabs for each site
How to swab in both?
Amies charcoal medium
Labelled date, time, horse
name, site
Sent to registered lab
If infection with any of the 3 organisms suspected - what must be done:
» All breeding activities must cease immediately
» Affected horse(s) should be isolated and swabbed
If CEM confirmed - what to do?
- Notify APHA (lab will notify if T.equigenitalis) and follow instructions
- Stop mating/teasing/collection of semen * Isolate the affected horse(s)
- Arranging swabbing of in-contacts
- Disinfect all breeding equipment
- Inform owners, national breeders association
- Test 1 straw from ‘at risk’ stallions
- ‘At risk’ mares to be foaled in isolation – incinerate the placenta
Tx for CEM?
Topical antibiotics, and cleaning penis/vagina with antibacterial wash
Prevention of CEM?
- establishing freedom from infection before commencing breeding activities * checking that horses remain free from infection during breeding activities * exercising strict hygienic measures during breeding activities
Are any vaccines available?
no
How to estanlish freedom from disease with CEM?
» Swabs taken from genitalia of mares/stallions – lab culture and PCR for presence of T. equigenitalis,
K.pneumoniae and P. aeruginosa
What next steps for each possible result of swabs?
- If the results are negative, the horse is free from infection and breeding activities may take place.
- If the results are positive, the horse is infected and must be treated, re-tested and cleared.
- The horse must not be used for breeding activities at this time and APHA must be notified
- No horse should be used for breeding activities until or unless all swab results are available and negative
What hygiene measures for CEM?
Staff should be made aware of the risk of direct and indirect transmission of infection. They should
always wear disposable gloves when handling the tail or genitalia and change gloves between each
horse. Separate sterile and, where appropriate, disposable equipment and clean water should always
be used for each horse.
» Biosecurity protocols specific to AI
