FMDV/oral cavity disease Flashcards
Clinical presentation of oral cavity diseases
- Protrusion of the tongue
○ May occur due to discomfort in the mouth or due to swelling of the tongue itself - Quids
○ Partly chewed lumps of food may be present called ‘quids’ - due to incomplete mastication and can sometimes be expelled into feed troughs or the floor - Oedema
○ Can occur in the submandibular space - Swelling
○ May be present in the head, lips or mandible - Penetrating wounds
○ Including erosion, ulceration, necrosis and vesiculation of the oral mucosa may be present - Ptyalism
○ Also known as excess salivation or drooling
○ May be present as a result of lesions, obstruction, or failure to effectively ingest, chew or swallow - Anorexia or inappetence
○ Common and can be relative or complete - Bloat
○ With the associated complications for anorexia and gut stasis may also be present
Oral cavity CE
- Suitable restraint (head yokes/bulldog clips)
- Equipment required
- Good light source
- Mouth gag/towel
- Halter/bulldog
- Sedation if necessary
Main viral differential diagnoses for oral cavity diseases
○ BVD
○ MCF (Ovine herpesvirus-2)
○ IBR (BHV-1.1, 1.2 respiratory)
○ Bovine papular stomatitis / orf (parapox virus)
○ Rabies
○ FMD
○ BTV
Main bacterial differential diagnoses for oral cavity diseases
○ Calf diphtheria
○ Actinobacillosis (Wooden tongue)
○ Actinomycosis (Lumpy jaw)
Main traumatic differential diagnoses for oral cavity diseases
○ Choke
○ Drenching gun/bolus
○ Caustic chemicals
○ Teeth
○ Vagal nerve damage
Stomatitis
= inflammation of the oral mucosa
Acute active stomatitis main CS
○ Ptyalism*
○ Dysphagia
○ Repetitive jaw movements
○ Excoriations and ulcers
○ Halitosis = secondary bacterial infection
Stomatitis ddx - non-infectious
= simple stomatitis causes
- oral trauma
- chemical irritants
Stomatitis ddx - infectious
§ IBR
§ Papillomas
§ BVDv
§ MCF
§ BPS
§ Vesicular diseases
IBR CS
□ Grey pinpoint pustules on soft palate
□ Pyrexic
□ Resp signs
Oral papillomas
□ Young animals
□ Pink-white raised with proliferative appearance on lips and mouth
□ Spontaneous resolution
BVDv CS
□ Small ulcers from mouth to rectum
□ Pyrexia and diarrhoea
MCF CS
□ Sporadic
□ Bilateral corneal opacity, nasal and oral discharge
□ Enlarged LN
□ Pyrexic
□ Dysentery
□ Catarrhal inflammation and erosions
BPS
= bovine papular stomatitis
□ Usually asymptomatic
□ Zoonotic
Vesicular dz
□ FMDv: pyrexic, lameness, vesicles on coronary band and mouth
□ VS: restricted to oral mucosa
□ BTV: swollen head, ears and lips
Importance of FMD
- Animal welfare
○ Painful and debilitating disease both short and long term
○ Movement restrictions can lead to overstocking - Social
○ Can be devastating for farmers - Economic impact
Disruption of internal and external market
FMD aetiology
- Disease is caused by infection with a picornavirus family (genus Aphthovirus) named foot-and-mouth disease virus (FMDV)
- The surface-exposed capsid proteins (VP1, VP2, VP3) of the virus determine its antigenicity and the ability of the virus to interact with host receptors and cause disease
- Distinct serotype: A, O, C, SAT1, SAT2, SAT3 and Asia 1
- No cross-immunity between serotypes
FMD transmission
shed in:
- breath
- secretions & excretions
- animal products
contaminates:
- air
- people, vehicles, equipment, feed, roads, etc
- milk, meat, rest of carcase
transmission routes:
- direct contact with aerosols via resp tract
- direct contact and indirect contact with secondary aerosols (resuspension) or via abrasions/ingestion
- indirect contact via ingestion or secondary aerosols
FMD pathogenesis
- Pre-viraemia - the period from when an animal is 1st infected with FMDV until virus is 1st detected within the intravascular (i.e. blood)
- Viraemia - the period during which FMDV can be detected within the intravascular compartment. This period typically coincides with the clinical phase of the disease
- Post-viraemia - the period following viraemia starting with the 1st negative assay on blood (determined by VI or detection of viral RNA) which includes
a. Resolution of clinical signs
b. Short-term persistence of infectious virus, antigen and/or RNA in specific tissues
c. Persistent infection (carrier state)
d. Chronic long-term sequelae including hirsutism, heat-intolerance (panting) and thyroid dysfunction, have been reported in recovered cattle
FMD clinical signs
- Incubation period - 2-12d
- Salivation, characteristic ‘smacking’ jaw movements
- Vesicles and ruptured lesions (muzzle, inside the mouth, feet)
- Abortion
- Anorexia
- Lameness
- Recumbency
- Low head carriage
- Dullness
FMD CS in cattle
- Often severe
- Depression, anorexia, possibly recumbency
- Profuse salivation
- Sudden death calves (myocarditis)
- Abortion
- Milk drop (usually before onset of other clinical signs)
FMD CS in small ruminants
- Often less severe than cattle
- Vesicles on the tongue, dental pad, along the coronary band and/or interdigital space, anorexia, possibly recumbency
- Vesicles can be difficult to see
- Sudden death in lambs/kids
- Animal may develop secondary infection
Abortion
FMD cattle ddx
○ Vesicular stomatitis
○ Bovine papular stomatitis
○ Bluetongue
○ Bovine viral diarrhoea
○ Mucosal disease
○ Infectious bovine rhinotracheitis
○ Actinobacillus ligneresi
○ Trauma, chemical burns, photosensitisation
○ Rinderpest (eradicated)
FMD small ruminant ddx
○ Bluetongue
○ Parapox virus (orf)
○ Peste de petitis ruminants (PPR)
○ Oral trauma
○ Trauma, chemical burn, photosensitisation
○ Laminitis, foot-rot, abscesses
FMD diagnosis
Penside:
- vesicular fluid, epithelium suspensions
- Very rapid
- Highly specific
- Side-cow test
- Not recognised confirmatory test
- Sensitivity varies between serotypes
Virus isolation (VI) cell culture:
- vesicular fluid, epithelium
- highly specific
- can take up to 4d
Antigen ELISA:
- vesicular fluid, epithelium
- Can determine serotype
- Less sensitive than VI or RT-PCR, so not applicable to blood or swab samples
Serology - antibody detection:
- clotted blood
- Confirms FMD in the late stage of the disease once the virus has cleared
- Not useful in acute stages of diseases
- Ab from previous infection/vaccination can make interpretation difficult
RT-PCR:
- More sensitive than ELISA or VI
- Doesn’t need live virus
- Usual methods don’t determine serotype
FMD diagnostic priority:
- Vesicular fluid sample is best if you can get it; otherwise, epithelium from a recently ruptured vesicle is best
- Even a swab sample from a recently ruptured vesicle can yield virus
- Blood samples should always be taken
FMD - in the case of an outbreak
Suspicion of FMD or any signs of a notifiable vesicular disease in a susceptible animal must be notified immediately to the local AHVLA Office. The duty Veterinary Officer (VO) will then discuss the clinical signs and health status of the suspect animal over the phone with the person reporting the suspicion. Based on these discussions, the duty VO will either rule out FMD or request a VO attend the premises to undertake a full disease investigation.
Main points:
* Contact tracing
* Establishment of protection and surveillance zones
○ National authorities must establish a protection zone with a of at least 3km and a surveillance zone with a minimum radius of 10km around the site of infection
○ Restrictions on the movement of susceptible animals in and out of the areas
○ Conditions for the dispatch of products from the susceptible animals from these zones
* Culling of infected animals
* Emergency vaccination
* National livestock movement ban
* Restriction of movement of animal products
* Cleansing and disinfection of premises
* Surveillance
What is the impact of FMD on trade?
- The OIE has a disease-free status list related to certain diseases, including FMD. That serves as a guideline for countries when deciding on their import policy
- Outbreak = the whole country loses its FMD-free status
- Until the free status is recovered, other countries can ban live animals and animal products from the affected country
- Several scenarios to recover the free status, depending on whether or not vaccination is used to control the outbreak
- The shortest period in which disease-free status can be recovered is 3m after cull of the last infected animal