Diagnostics and Vaccines Flashcards
What is the main principle of vaccination?
Expose host to foreign Ag w/out causing dz or adverse effects
What is passive immunisation?
Admin of Ab: colostrum or antiserum (e.g. tetanus)
What is active immunisation?
Give the animal Ag: toxoids, MLV (weakened version), killed, subunit, recombinant (using vector)
What is the chosen method for delivery of vaccines?
SC/ IM- systemic protection
IN- mucosal immune response (IgA rather than IgG)
What are the basic principles for vaccination protocols?
MLV/ recombinant viral- normally only 1 dose in animals >3m (beyond MDA) unless specified (not v potent)
Killed/ subunit- normally require 2 doses given 2-3wks apart.
No point in animal<12 weeks
What are the core and non-core vaccines for dogs?
Distemper, parvovirus, adenoviruses (canine infectious hepatitis), rabies in endemic areas
Non-core- leptosprirosis (diff serovar), kennel cough (Pi, Bp, coronavirus)
What is the primary course for vaccination in dogs?
MDA 8-14wks.
3 doses at 8, 12, 14-16w. Serology at 20w recommended
What are the breed differences with regards to response to vaccines?
Black and tan breeds reported to be poor vaccine responders e.g. Doberman, rottweiler. certain MHC types. Worth doing serology to check response. Poss 3rd dose at 16w
When should the animal receive a booster against core and non-core vaccines?
Booster at one year. Pi, Lepto, Bordetella- often not v immunogenic so may require booster every year. Whereas core vaccines only require it every 3yrs. W/ lapsed booster don’t need to start 1ry course again. Memory lymphocytes don’t forget!
What are the core and non-core vaccinations recommended for cats?
Core- calici, herpes, panleukopenia.
Non-core- FeLV
What is the efficacy of the different cat vaccines?
FPV- high degree of protection
FCV and FHV- not as efficacious. FCV multiple strains. FHV only protects against clinic dz not infection, can remain latent.
What is the recommended vaccine protocol for cats?
CHP 8, 12, 16w.
Booster 1yr
Then every 3 yrs
What is feline injection site sarcoma?
Associated with adjuvant in FeLV/ rabies vaccine. Annual exposure of tissues to mutagenic compound- vary vaccine site
What are the vaccinations used for rabbits?
Myxomatosis
Viral haemorrhagic dz
When do we use passive immunisation in horses?
Hypermune equine plasma for FPT
Tetanus antitoxin
Rotavirus vaccine for pregnant mare for MDA transfer to foal
When do we use active immunisation in horses?
Equine influenza
Tetanus toxoid
EHV-1, EHV-4
Others- WNV, EVA, strangles
What are the reasons for vaccine failure?
Diff strains/ serotypes in population. Not stored properly/ expired. Not admin properly. Too young/ too old. Interference by MDA. Prior exposure to pathogen. Immune suppressed/ immunocompromised. Genetically programmed to generate inappropriate response (MHC genes in Rotty)
What is the basic principle of serology testing?
Recommendation: 3-4 wks after primary course and prior to deciding on booster requirement. Not often performed. If testing early in course of infection test for organism (culture, PCR, immunoassay for Ag), if >5d post exposure test for Ab in serum (log) and then retest 2-3wks later (plateau). IgM 1st Ab then class switches to IgG
What serological testing is available in dogs?
Dx of specific infection- CDV, CPV, CAV, CHV, coronavirus, PI
For Ds w/ neurological dz, myositis, PUO- toxoplasma or neospora
Acute kidney dz- leptospira spp
Can be used for aspergillus and cryptococcus when fungal rhinitis is suspected
Scabies serology can be used for dx of sarcoptic mange
What serological testing is available in cats?
Suspected infection with- FIV, toxoplasma/ neospora, cat flu (calici, herpes, chlamydophila)
Care re FIP as exposure to coronavirus common in cat population.
What serological tests are available in horses?
Specific pathogen suspected in outbreak- EHV, influenza
Certified pathogen free for import/ export/ pre-breeding and sales- EVA, EIA (may require multiple tests due to lag phase)
What are the diagnostic options for diagnosing disease in cattle?
Herd vs individual test (give herd estimate): bulk test- any contagious dz Split bulk tank- any contagious dz Young stock- typically BVD Individual cows e.g. bTB
What are the current disease tested for Ab in the bulk tank in dairy cows?
BVD
Johnes (may require individual as not v sensitive)
IBR
Lepto
What are the different tests used in cow herd diagnostics?
Ab ELISA- typical test used Cell-mediated response (TB) Pathogen ELISA- BVD Pathogen PCR- mastitis Pathogen culture Slaughterhouse PME
Which tubes are used for different diagnostic tests?
Serology, blood- plain tube, red
PCR and Ag ELISA, blood- heparin tube, green
Serology and PCR, milk- tube w/ preservative, prevents growth of bacteria
Culture, milk sterile pot w/out preservative e.g. for mastitis
What is parallel vs serial testing?
Parallel testing- e.g. bovine TB, test a lot of cows, if 1 cow +ve the herd is +ve, incr sn, decr sp
Serial testing- if get +ve use another test to confirmed, used in eradication programmes, incr sp, decr sn
How does the sample size vary when testing for presence or absence of dz?
For presence usually big sample
For dz free proof sample typically smaller as with infectious dz is 1 +ve then more will be
Why is a license required for use of a Johnes vaccine?
Would interfere with test for TB
Why are vaccines used as part of disease management in cattle?
Reduce pathogen load (Lepto)
Protect from reintroduction (BVD)
Improve efficacy of current practice (rota/coronavirus to complement colostrum management)
Raise herd immunity reduces load, reduces infected, eradication
What is the DIVA?
Vaccine which allows differentiation of infected from vaccinated. Available for IBR, AI, FMD, bTB
What are the different types of vaccine used?
Live- immunity vs spread after inoculation
Attenuated live- local immunity developed
Dead- response depends on adjuvant
Subunit
Toxin based
Boosters
How does a conventional radiograph create an image?
Film in cassette sandwiched between screens. Screens emit green when Xray beam passes. Film sensitive to green light. At places where XRays went through the screen and light was emitted now have exposure of photographic emulsion in film adjacent to screen. Once exposed go to dark room and process. Dip to developer, fixer and then wash (or automatic processor)–> image
What is the difference between computed radiography and digital radiography?
CR0 uses storage phosphor image plates, exposed then laser beam scanned and cleared
Digital- converts xrays into electrical charges more or less directly
What is the photographic density?
Degree of blackening of the film. Determined by xray exposure- greater exposure greater the density. Underexposure in digital won’t necc look lighter but will look noisier
What is the contrast of a radiograph?
Range of grey shades in a radiograph. Needs a fine balance to see anatomy
What is the resolution of a radiograph?
Capacity to render detail. Low resolution images described as blurred. May result from movement, excessive scattered radiation, fogging, damage to cassette, many other factors
What are the Rontgen signs (6) of an XRay?
Number- congenital/ acquired/ apparent
Position
Size- hypertrophy/ hyperplasia, infiltration, congestion, dilatation or hypoplasia, atrophy, fibrosis, hypovolaemia
Shape
Opacity
Margination- can only see boundaries due to different opacities (lack of serosal detail in young due to no fat)
What are the four normal radiographic opacities?
Gas
Fat
Soft tissue- blood, urine, bile, transudate, exudate, muscle, parenchymal organ
Calcified tissue
What is the principle of ultrasound?
Transducer sends sound waves and collects returning echoes. Time to return determines distance to structure. Majority continues through rest.
What are the different modes of ultrasound?
M-mode: non anatomic images used for measurements of cardiac chambers, valves (over time)
B-mode: cross sectional anatomical image
What is the echogenicity of a structure?
How many echoes it generates. Liver hypoechoic- darker- less echoes. Spleen hyperechoic- lighter- producing more echoes.
What factors influence echogenicity?
Increase/ hyperechoic- fat, glycogen, collagen, vascularity, crystalline material
Decr/ hypoechoic- oedema
How does the shape of the transducer and its frequency determine its application?
High fz (e.g. 7.5MHz)- detailed exam of small/ superficial structures Lower fz (3.5MHz)- less detailed exam of deeply situated organs Wide, flat (linear) best for flat body parts e.g. equine metacapus Narrow, curved transducers for intercostal spaces
What computed xray tomography?
Producing cross sectional images that involves irradiating the subject using high energy, fan shaped circulating xray beam and capturing transmitted photons in electronic detectors positioned in a ring around the patient.
What is the window of a CT image?
Narrow window (of housefield units)- high contrast, distinguish soft tissues (i.e. all bone outside housefield range therefore no variation) Wide window- lower contrast, more bone detail
How does MRI work?
Based on magnetism of different elements of the body. Nuclei containing an unpaired proton spin creating a magnetic field- H+ most numerous in body. MRI scanner aligns protons up or down- small majority in up direction. Then apply small magnetic fields to change orientation of atomic nuclei and collect radio waves that are emitted
What are the 2 images produced w/ MRI?
T1w- fluid black
T2w- fluid white
Why are some diseases notifiable?
Serious welfare/ potentially life threatening. Serious economic/ trade importance. New and emerging. May be absent in a population/ eradication plan. Pathogens acquiring resistance. Zoonoses. Trans-boundary animal dz. Spreads rapidly. Can’t be easily tx or cured e.g. no vaccines/ abx
