Selected GI disease Flashcards
What type of virus is BVD?
- Pestivirus
How are biotypes determined?
In vitro designations
Non-cytopathic BVD
- Do not destroy cells
What is the predominant biotype?
- Non-cytopathic
- Persists in cattle populations
Reservoir for non-cytopathic BVD
- PI animals
How does cytopathic BVD happen?
- Via mutation of non-cytopathic
What is BVD mucosal disease?
- Co-infection of homologous NCP and CP
Which versions of BVD cause clinical infection and disease? Which is not found as a cause of PI animals?
- Both cause clinical infection and disease
- CP is not found as a cause of PI animals
Significance of species BVD
- There are Type I and Type II with a bunch of subspecies
- Might be an explanation for why vaccines don’t work as well
Type I species of BVD
- many subspecies
- NCP and CP
- Worldwide now
WHat is the outstanding feature of Type II BVD?
- Thrombocytopenic strains
- Causes some more damage too
- NCP and CP
BVD Type I and Type II Antigenic and genetic similarity?
- They are DISSIMILAR with regards to both antigen and genetics
- Means that antibodies likely aren’t cross-protective, and may be why some vaccine companies are putting multiple strains
BVD Type I and Type II - disease syndrome differences
- They are similar
Seroprevalence of BVD
- 60-85%
- It’s widespread
- 60-80% of cattle >1 year have seroconverted
Source of infection for BVD
- Persistently infected animals!!
- They are responsible for persistence in herds
How common are PI calves?
- ~2% of general cattle population
- 10-50% of US herds have at least 1
Transiently infected calves
- They get it and may get affected a little but usually get through it
- 1-2 weeks, seroconvert, and become part of the group that has had it
Transmission source of BVD
- PI or TI animals
- shedding it everywhere
How long does BVD last in environment?
- <2 weeks in environment
- Can persist in the environment
Transmission of PI vs TI
- TI shed fewer, shed for a shorter period of time compared to PI
Where is BVD secreted?
- Most body secretions
Transmission of BVD mode
- Direct contact (ignestion, inhalation, etc.)
- Vectors (insects and inanimate)
- Transplacental (virtually 100%)
- Semen (AI are tested previous to using them)
BVD in pigs and wild ruminants and pigs
- Isolated from many domestic and wild ruminants and pigs
Clinical sign variability in BVD
- Subclinical to death
- Hugely variable
What determines BVD variability?
- Immunotolerant vs immunonaive
- Immune status (exposure, vaccines, etc.)
- Stressed animals are worse off
- Pregnancy status
- Gestational age
- Environmental stress
- Genetic diversity of virus
When are PI calves infected during gestation?
- 30-150d (<125 d in utero)
PI calf pathophys
- Fetus is immunotolerant
- NCP virus persists, no effective immune response
Clinical appearance of BVD
- Clinically normal
- Weak, poor do’er, immunosuppressed
Which biotype of BVD infects PI calves?
- Non-cytopathic
Who are we most worried about protecting during gestation for BVD?
- Pregnant cow!
<60 d BVD infection signs
- Abortion, early embryonic death, congenital defects
60-120 day BVD infection signs
- PI calf
- Commonly die young but may rarely live to produce more PI calves
- Always shedding large amounts of BVD
- Immunosuppression
100-150 days signs BVD infection
- Congenital defects
> 120 days clinical signs BVD infection
- Calf born with antibodies to BVDV, may be normal or stunted
Significance of PI cows that are at repro age
- may need to test more than just calves
- Cows can do it too
What is the most common manifestation of BVD?
- Acute BVD (TI)
When do cows experience acute BVD most often?
- 80% in 1st year life
Who gets acute BVD?
- Immunocompetent but naive animals or fetuses >150-180 days
Acute BVD morbidity and mortality
- Most inapparent***
- High morbidity, low mortality
How long are most cows infected with BVD if acutely infected?
- Several weeks, but short lived viremia (2-3 weeks)
- Seroconvert but virus negative with time
Clinical signs of Acute BVD (TI)
Fever, lethargy, nasal/ocular discharge
- Diarrhea/enteritis
- Mucosal erosion***
- Neutropenia
- Respiratory disease**
- Profuse diarrhea and agalactia in adult dairy cattle
- Virus damages epithelium of GIT, integument, and respiratory systems
BVD and Bovine Respiratory Disease Complex
- Remember that BVD sets you up for BRD***
Ulcerative lesions and BVD
- Around the coronet, nose, any mucosal surface
Most common signs of acute BVD***
- Inapparent!!!
Papillae in the mouth with BVD***
- They are blunted
Thrombocytopenic/hemorrhage syndrome BVD - which type of BVD?
- Acute, type II, NCP, BVD
Mortality of Thrombocytopenic/hemorrhage syndrome BVD
- Higher mortality and more severe signs
Mechanism of Thrombocytopenic/hemorrhage syndrome BVD
- Unknown
- Virus associated with platelets, megarkaryoctes, and platelet function is altered
Clinical signs of Thrombocytopenic/hemorrhage syndrome BVD
- Severe GIT bleeding, epistaxis, hyphema, bleeding from injection sites, etc.
- Ecchymoses of heart and lungs (you will find on necropsy)
Who gets mucosal BVD?
- PI animals ONLY***
- Following fetal infection <125 days with NCP virus
Clinical signs of mucosal BVD
- Fever, lethargy, dehydration, diarrhea, mucosal erosions, neutropenia, lymphopenia, respiratory disease, acute death
- MOST OFTEN DIE
Severe acute BVD and Mucosal disease
- Clinically indistinguishable from severe acute BVD
- They almost always go on to die!
Chronic MD
- RARE
- Occasional
- Can survive up to 18 months
- Intermittent diarrhea
- Poor appetite, weight loss, bloat
- Interdigital erosions, lameness
How does mucosal disease occur (MOST COMMON)?
- Combined infection of antigenically homologous NCP (persistent) and CP virus)
- Spontaneous mutation from NCP to CP (MOST COMMONLY)
Antigenic similarity of NCP and CP in mucosal disease
-They are antigenically homologous
Vaccination and Mucosal disease
- Combined infection of antigenically homologous NCP (persistent) and CP virus
- Natural or iatrogenic (MLV vaccine) infection
- Rare, but they’re already PI so need to be out of the herd anyways
What cells does BVD target for immunosuppression?
- Lymphocytes and macrophages
- Decreases CD4+, CD8+, and B lymphocytes as well as neutrophils
- Also decreases neutrophilic bactericidal activity
Immunomodulatory agents impacted by BVD
- IFN, IL-1, IL-2, and TNF-alpha
- These are the early indicators
Consequences of immunosuppression of BVD
- Much lower capacity to fight off disease
Congenital defects of BVD (100-170 d)
- Cerebellar hypoplasia
- Hydranencephaly/hydrocephalus
- Eye problems (microphthlamia, retinal atrophy, cataracts, optic neuritis)
- Pulmonary hypoplasia (small lungs; die after death)
- Skeletal defects
- Thymic hypoplasia
Infected during 1st trimester BVD outcome (0-110d)
- Abortion, congenital damage, PI calves
During which trimester can BVD calves be born?
- 1st and 2nd trimester overlap
Infected during 2nd trimester BVD outcome (111-180d)
- Congenital damage, fetal loss
Infected during 3rd trimester BVD outcome
- Fetus immunocompetent and mounts a response
Other syndromes with BVD
- Repro failure, infertility, repat breeders
- Abortion, mummies (infected <100 d)
When are mummies infected?
- <100 d
Leukogram for BVD
- Leukopenia
- Lymphopenia
- Neutropenia (severe, no left shift; helps differentiate from Salmonella which will normally have a left shift )
- Thrombocytopenia
Thrombocytopenia in BVD
- < 100,000/µL
- Can bottom out <10,000/µl
- Acute type II, NCP BVDV
Dfdx for BVD WITHOUT oral erosions in adults
- Salmonella (has a left shift)
- Winter dysentery
- Johne’s
- Copper deficiency
- Ostertagiasis
- Coccidiosis
- Grain overload
- Renal amyloidosis
Dfdx for BVD WITH oral erosions in adults
- Vesicular stomatitis
- MCF
- BT/EHDV
- FMD
- Papular stomatitis
- Rinderpest
- BVD
Suspicion of BVD signs
- Herd records (decreased production, poor repro performance, signs of immunosuppression)
- Signalment and history
- Clinical signs and CBC
- Pathology and histopathology (necropsy super helpful)
Herd records of BVD herds
- Decreased production
- Poor repro performance
- Signs of immunosuppression
Peyer’s patch in BVD
- CAN be hemorrhagic in BVD
VI for BVD sample
- Blood, feces, nasal swab, tissue
VI for BVD - when to use?
- Not used that often
- Used when you don’t know what’s going on exactly
- Used when you’re pretty certain it’s a virus but not sure what type
BVDV Ag ELISA sample
- buffy coat or serum or ear notch
BVDV Ag ELIA when to use?
- This is a very common test to define the PI calf
- The reason it’s useful is that it’s not that sensitive for BVD
- Less likely to detect a transiently infected animal at all
- This is how you determine a PI calf
BVDV IHC - what sample?
- Ear notch
BVDV ICH when to do?
- Ear notch
- They can take those and pool them and test that way or individually
- IHC can be done at WADDL for PIs
Serology for BVDV
- Negative titers suggest PI animals (normally 80% animals are +), definite if VI+
- 4x rise suggests clinical BVD
- Precolostral titers positive suggests exposure (but a pain to do)
- Much less frequently used
- Cross reacts with vaccines
- Sometimes used to determine if an abortion outbreak
- Compare a group of 10 cows that did abort and 10 that didn’t
- Then measure again 3 weeks later
- His preference is every aborted fetus, placenta, and serum from the cow
Issues with serology for BVDV
- Cross reacts with vaccines
- Kind of a pain
PCR for BVDV which sample?
- Ear notch
PCR for BVDV when to use?
- This is the test that almost everyone has gone to for detecting PI
- They will follow this up with BVDV Ag ELISA to determine that it’s PI and not TI
- PCR is super sensitive
Treatment for MD BVDV
- None
Treatment for acute BVD
- Support
Treatment for hemorrhagic syndrome
- May need transfusion
Main principle of control for BVD
- Eliminate PI animals
Testing for BVDV with new animals
- Test all incoming (ELISA or PCR)
- Quarantine all incoming for 1 month
What to do for BVD testing if herd tests have not been performed in the past
- Test all open cows or cows that lost calves
Vaccination of BVDV - will it eliminate disease?
- NO
- May mask clinical signs
- Still see repro problems and PI calves
WADDL recommendations for testing - who to test?
- Test ALL calves
- Test all bulls and replacement heifers that have not been tested (cows lost calves)
WADDL recommendations for testing - what to test?
- Ear notch test (pooled PCR of 36 animals)
- Individual test with Ag ELISA if positive (PI)
WADDL recommendations for testing - what to do with positive animals?
- Quarantine
- Retest in 2-3 weeks (2% false positives)
What to do with PI animals?
- Euthanize, slaughter, BVD feedlot (???)
- Don’t sell your problem
<12 samples for BVD Ear Notch testing
- No pooling
- Just do Ag-ELISA
At 36+ samples BVD Ear notch testing
- Do the PCR pool up to 36 and then Ag-ELISA per head if needed
Which BVDV tests go for antibody?
- Serology
- Also use to determine type I and type II
Which BVDV tests go for antigen?
- VI
- PCR
- Ag ELISA
- Ag IHC
Which test for export testing?
- Viral isolation
- 5-9 days for results
Can PCR differentiate PI and TI?
- No
- Too sensitive
Can Ag ELISA differentiate PI and TI?
- Yes
- Only detects high levels of antigen
- Good for herd screening
WHich are screening tests for BVDV?
- Ag ELISA
- PCR
- Ag IHC
Cow vax recommendations for BVD
- Prevent fetal infection
- 2 weeks to 2 months befor ebreeding
- Revaccinated annually (if they’re set up young though it’s usually okay)
- Need to start young
Calf vax recommendations
- Protect against systemic infection
- +/- branding (MAY be too young though!)
- 3-4 weeks before weaning
- 3 times the first year
Which products for BVDV vaccinations?
- Killed vs MLV
- Brand
Which type of vaccine for BVDV in a cow that didn’t receive vaccines prior to breeding?
- Have to use killed
Brand of BVDV vaccine
- He recommends using the same vaccine throughout life
What causes and influences coccidiosis?
- Caused and influenced by MANAGEMENT
Etiology of Coccidiosis
- Eimeria and Isospora
Can Eimeria in cattle infect sheep/goats and vice versa?
- No, unless immune compromised
PPP of Coccidiosis
- Variable with species
- They don’t shed until at least 17 days
- Don’t have clinical signs until shedding
Where is coccidiosis normally found?
“Normal” inhabitant of adult GIT
Who gets Salmonellosis?
- All species
Prevalence of Salmonellosis?
- CA dairy herds up to 75%
Is Salmonella host specific?
- No, most serotypes are non-host specific
Make sure you go back and make notecards for the one lecture you missed on 3/7
:)
Carriers and Salmonellosis
- Host adapted Salmonella, which increases chance for carriers
- They can make a carrier state
Subclinical infections of Salmonella
- If you have clinically affected, there are probably a great many more that are subclinically affected
Age groups for Salmonella
- From the day they are born on
- It can impact a 1 day old calf or a 15 year old calf
Main etiologies for calf diarrhea in the first few days of life
- E. coli
- Salmonella
- Also Campylobacter and Clostridia, but the others are the main two
How can Salmonella invade?
- Ocular, nasal, oral, GIT mucous membranes
- S. dublin via ingestion of milk from intramammary infection
Stress and Salmonella
- Stress can lead to a recrudescence of of Salmonella
- Shed via feces or milk
What age group of animal can get Salmonella and which types of serotypes?
- Any age animal
- Only invasive serotypes
What are the three mechanisms of diarrhea for Salmonella?
- Inflammation and necrosis
- Increased fluid secretion
- Decreased absorption and digestion
- Increased fluid secretion
How does inflammation and necrosis occur with Salmonella?
- Salmonella attacks the villi and invades to lamina propria
- Macrophage response destroys organism and/or tissues
- PMN response (inflammatory edema)
How does Salmonella increase fluid secretion (hypothesis)?
- Locally induced PG production stimulates adenylate cyclase –> increased fluid secretion
How does Salmonella decrease absorption/maldigestion?
- Damage to intestinal villi (decreased digestive enzyme production)
- Blockage of lymph and blood flow (impede nutrient and fluid uptake which leads to an osmotic type diarrhea)
- Fusion of villi (secondary to healing; decreased absorptive surface area)
Clinical presentations for Salmonella
- Peracute septicemia
- Acute enteritis
- Chronic enteritis
- All three can be concurrent in a herd
What 3 things determine individual Salmonella disease?
- Virulence of serotype, pathogen concentration, and immune status of host
Who typically gets septicemia from Salmonella?
- Calves and lambs 10 days to 3 months
Which serotypes cause Salmonella septicemia?
- S. typhimurium, S. dublin
Clinical signs of septicemia/endotoxemia
- Scleral injection
- Petechiation (pinna)
- Toxic (gum) line
- Recumbent, dead
- Can be found dead with minimal signs
Course of Salmonella
- Hours to 1-2 days
Neurologic form of Salmonella signs
- Opisthotonus, convulsions
Enteric form fo Salmonella septicemia signs
- Diarrhea, colic, etc.
Typical hemogram with septicemia
- Leukopenia (profound)
- Hyperfibrinogenemia
- Left shift (severe)***
- Metabolic acidosis (+/- diarrhea, dehydration)
Sequela for Salmonella septicemia
- Polyarthritis, fibrinous pneumonia
Predisposing factors for Salmonella
- Failure of Passive trasnsfer
- You would want to check your program if you have an increase in Salmonella
What is the predominant form of Salmonella?
- Acute enteritis
Clinical signs of acute enteritis with S. typhimurium, S. newport
- Fever, enteritis, anorexia, depression, dehydration
- Diarrhea later
- Watery at first
- FOllowed by mucosal shreds, casts, blood, foul odor
- Dehydration worsens, hypothermia, etc.
S. dublin clinical signs with acute enteritis
- Fever, anorexia, depression
- Calves can die without diarrhea***
- More likely to see meningitis, polyarthritis, osteomyelitis, pneumonia
- Adults can get abortion
Can calves die without diarrhea with S. dublin?
- YES
Hemogram for acute enteritis
- Initial leukopenia
- Later (3-4 d) - leukocytosis, left shift
- Hyperfibrinogenemia
- Metabolic acidosis
- Hyponatremia
- Hypokalemia (whole body)
- Hypoproteinemia in the face of an elevated PCV
Mortality of acute enteritis with Salmonella and what determines it?
- 0-75%
- Depends on the health of the group of calves, how naive they are, and the virulence of the strain
Postmortem signs with Salmonella
- Enteritis (If they’ve been dead longer than 6-12 hours you can’t see this regardless)
- Erosions of small and large bowel
Who gets chronic Salmonella enteritis?
- Older calves (6-8 weeks)
Clinical signs of Salmonella chronic enteritis?
- “Failure to thrive”
- Scruffy
- Loose stool (not diarrheic)
- No mucosal shreds, blood, casts
-
Postmortem signs of Salmonella chronic enteritis
- Localized necrosis of cecum/colon
- button ulcers
- Pseudomembranes (yellow/gray)
S. dublin - where can it exist?
- Endemic in certain farms (adapted strain)
- Can persist in mammary glands, source of chronic mastitis