Anatomic Pathology Readings 11-14 Flashcards Preview

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Flashcards in Anatomic Pathology Readings 11-14 Deck (77)
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1
Q

How can you get a cDNA (copy of DNA) for PCR of an RNA infectious agent?

A

Use the enzyme “reverse transcriptase” to promote synthesis of DNA from the RNA template = cDNA (copy of the DNA)

2
Q

How does PCR work?

A
  • Primers (nucleotides) compliment intended target DNA and are added to reagents
  • heated to separate DNA to two strands
  • cooled to allow primers to bind to DNA
  • heated again
  • 25-40 cycles
  • PCR products (amplicons) read by gel electrophoresis
3
Q

Advantages of molecular approaches:

A
  • Faster and no need for special media
  • Diagnose organisms hard/slow to grow or ones that cannot be cultured
  • Detect evidence of infection before Ab response
  • Clarify Ab + due to infection or maternal Ab
  • Document latent infections or carriers
  • Diff btwn pathogenic and non-path or vaccinal isolates
  • Retrospective analysis and characterization of zoonotic infection
4
Q

PCR can help dx organisms that cannot be cultured like:

A
many viruses
some mycoplama (haemobart)
5
Q

PCR also good with disease organisms that grow slowly for example:

A

mycobacteria

6
Q

Good examples of diseases that historically have required seroconversion but now can be diagnosed via molecular assays: name 2

A

RMSF (rocky mountain spotted fever)

Leptospira

7
Q

Examples of a PCR clarifying infectious dz or maternal Ab

A

FIV (otherwise can’t tell!)

8
Q

T/F: PCR and RFLP (Restriction fragment length polymorphism) can help select appropriate antimicrobial therapy.

A

true

9
Q

List Koch’s 3 postulates:

A
  1. Agent found in every case of the disease
  2. Agent was not found in other diseases
  3. Agent can be isolated and cultured and cause disease in a new host
    (4. Agent could be isolated from the experimentally inoculated host)
10
Q

Why use Koch’s postulates - what do they mean?

A

They show that a given agent was the cause of clinical disease if the postulates were satisfied

11
Q

What’s considered an additional point of proof of infect dz:

A

If an agent can be isolated from experimentally inocculated host

12
Q

When trying to find a cause for a disease, what is the most important first question for a clinician when they have detected an infectious agent?

A

Is it is likely that the infectious organism is truly responsible for clinical disease or other abnormalities?

13
Q

Give an example where the PCR-positive blood sample doesn’t guarantee an infection.

A

Hemobartonella = IMHA

Hemobartonella can cause IMHA but IMHA can be caused by other causes

14
Q

Are there known pathognomomic or typical gross lesions for anesthetic-associated death (AAD)?

A

no!

15
Q

Over half of cases with natural disease had ____ lesions which included:

A

pulmonary:

  • Aleurostrongylus abstrusus
  • pneumonia
  • acute aspiration pneumonia
16
Q

Pulmonary dz was the most common lesion tied to AAD, which two wereafter that?

A

-heart disease (2 HCM; 4 lymphocytic myocarditis)
-systemic (Panleukopenia; Toxoplasmosis)
(also CNS disease causing one death; noting hepatic lesions in 3 cases)

17
Q

What is the connection between renal disease and anesthetic-associated death (AAD)?

A

Of the 54 cases of AAD death, none had gross or histo evidence of renal dz! (no connection)

18
Q

What is the life cycle of Aleurostrongylus abstrusus

A
  1. Adult worms in terminal bronchioles
  2. Eggs are laid by females, with L1 coughed up and excreted
  3. L1 exits in the feces to intermediate host: snail, slug
  4. L1 matures to L3 in intermediate host and then either eaten by cat (DH) or paratenic host then to the definitive host
19
Q

t/f cats can never eliminate A. abstrusus on their own?

A

False! they will eliminate it after 5months and cannot be re-infected

20
Q

What is the gold stnd diagnosis of A. abstrusus

A

Baerman fecal exam

21
Q

Aleurostrongylus abstrusus infections results in: (2)

A
  • Granulomatous pneumonia
  • Hypertrophy and hyperplasia of tunica muscularis in the pulmonary artery = pulmonary hypertension (can persist for up to a year)
22
Q

What parasite other than Aleurostrongylus abstrusus can cause pulmonary hypertension in cats?

A

Dirofilaria immitis

23
Q

Why do cats die from anesthesia with pulmonary hypertension?

A

There is a decrease in gas exchange -> less blood back to LA -> LV

24
Q

There were cases with lymphocytic myocarditis- etiology?

A

Toxoplasma

Possibly Bartonella henselae or a cardiomyopathy

25
Q

Why can’t you rule out toxoplasma with a negative IHC?

A

It only takes a few of tiny T gondii tachyzooited to incite sign inflammation

26
Q

Can you detect a mechanical causes of death eg. soft palate occlusion or improper ET-tube intubation on PM?

A

no

27
Q

Can you detect respiratory acidosis secondary to hypoventilation on PM?

A

no

28
Q

Can you detect heart conduction failure on PM?

A

no

29
Q

What should you sample for histopath on stillborn, or neonatal death? (6 + 1 general)

A
Placenta
Liver
Kidney
Lung
Heart
Brain
Anything specific
30
Q

What should you sample fresh* for virology and bacteriology?

A
same as histo except also sample spleen but don't sample heart and brain
(Placenta
Liver
Kidney
Lung
Spleen
Anything specific)
31
Q

Who’s serum do you sample in fetal necropsy?

A

Dam and fetus

32
Q

What is most critical tissue to obtain on fetal necropsy:

A

Placenta! may have more info than fetus itself

33
Q

In the case of neonatal death, do what before opening up fetus?

A
  • record wt, measure crown to rump, check for hair growth and texture, check for teeth (teeth = close to term)
  • rinse fetus and fetal membrane and put on wet table to examine
34
Q

In the case of neonatal death, specifically check for these before opening up animal:

A
  • congenital defects (e.g. VSD)
  • evidence of redness, swelling, improper mobility= fx
  • umbilicus for swelling (hernia)
35
Q

In the case of neonatal death, what should you do once cavities are open:

A

Collect samples:

  1. virology/bact (1cm+)
  2. histo- in formalin (<0.5cm)
  3. Sample of blood & stomach contents in a red top tube with new needles
36
Q

When examining placenta on dog, if you see dark red-green band what do you conclude?

A

It’s normal! marginal hematoma on zonary band (zonary placenta) (pale brown and smaller in a cat)

37
Q

Cats placenta differs from dog placentas how?

A

The marginal hematoma is more narrow with less distinction and is pale brown

38
Q

It’s important to do this with placenta to check of evidence of inflammatory cells and bacterial organisms:

A

Take an impression smear of the chorioallantois

39
Q

What organism loves placenta?

A

Brucella organisms

40
Q

What if you see a red tinge on internal organs of fetuses?

A

incidental (unless well demarcated areas of obvious hemorrhage and/or edema are present)

41
Q

What about a clear yellow or red fluid in body cavities of fetuses?

A

incidental

42
Q

What if you see clotted blood within cavities in a fetus?

A

This is not normal- may indicate trauma

43
Q

Fetal mummification (dry, shrunken, wrinkled) can mean what?

A

Non-sepcific. Can point to a viral cause or many other causes in utero

44
Q

What is the cause/name of a fetus which is just a bag of bones with reddish brown uterine fluid?

A

This is fetal maceration and is commonly due to bacterial infection (specific to bateria*)

45
Q

What is an example of an incidental congenital defect?

A

hydrancephaly (brain’s cerebral hemispheres are absent)

unilateral renal agenesis

46
Q

What is the most common cause of viral abortion in neonatal dogs?

A

herpes!

47
Q

Clinical signs and PM findings with Herpes

A
  • Sudden death, lethargy, excessive crying

- PM: multi organ hemorrhage (kidney, lungs, liver most obvious)

48
Q

t/f herpes likes warm temp to grow?

A

FALSE! Herpes virus is optimized at lower temps

49
Q

You can confirm herpes infection with what tests?

A

histo and PCR

50
Q

How does having herpes affect pregnancy in cats?

A

Abortion is rare in cats with herpes. It is mostly tied as a secondary cause because of respiratory disease in the queen
BUT kittens can have neonatal death due to herpes

51
Q

List other differentials for sporadic abortions and neonatal deaths in dogs, other than the most common (herpes virus)

A

CPV-1 (canine parvovirus-1)
CDV (canine distemper virus) -> rare
CAV-1 (canine adenovirus-1) -> not typical; pneumonia in pups
BTV (bluetongue virus)
(can be secondary to maternal morbidity or due to direct infection)

52
Q

Ddx viral abortion and neonatal death in cats:

A
  • FeLV
  • FPLV (feline panleukopenia virus/parvo)
  • FIV
  • Feline coronavirus
  • FCaV (feline calicivirus)
53
Q

2 most common bacterial neonatal death in dogs:

A

Brucella canis (take more than 48 hours to culture)
Streptococcus spp
Others: salmonella, campylobacter, leptospira, e.coli

54
Q

Protozoal causes for abortion, stillbirth, neonatal death dogs and cats:

A

Toxoplasma
Neospora
(dogs and cats are DH for both)

55
Q

This virus is assoc with fatal pneumonia in puppies <4wks

A

CAV-1

56
Q

How do you tell if there was trauma with dystocia?

A

regional hemorrhage or edema

+/- fractures

57
Q

What makes you think infanticide?

A

hemorrhage in brain and broken skull

58
Q

seroconversion detects what?

A

active immune response 10-14days post inital challenge

59
Q

Serology is best used when?

A

Serology is best used to monitor for active infections in a group of cattle, rather than specific disease in a single animal

60
Q

“if animal test +, it has dz” =

A

pos predictive value

61
Q

VNT vs ELISA with serology

A

ELISA only tells you that Ab binds to Ag- may bind to part of virus that’s not nec for infection

VNT- demonstrates what amnts of Ab will neutralize the virus

62
Q

serology detection for bacteria: egs

A

varies: ELISA, CF, agglutination, leukotoxin inhibition

63
Q

LN vs antileukotoxin

A

LN measures fxn Ab which interfer with toxin b/c antileukotoxin binds to any leukotoxin (LN better indicator of + predictive immunity)

64
Q

problem with VI at cellular level

A

not all cells show cytopathy with certain dz’s (non-cyto BVDV)

65
Q

main disadv of VI

A
  1. takes 2 wks before actual -
  2. cells needed may be hard to get
  3. can’t find new or emerging viruses
66
Q

use EM for

A

enteric and sometimes resp viruses

67
Q

disadv of bacterial isolation

A
  1. tech has to pick correct colony
  2. bacteria present are all N in resp tract
  3. antibiotic therapy can = negative culture
68
Q

direct vs indirect FA

A

direct detects Ag

69
Q

disav of FA

A

dye won’t stay long without breaking down so can’t have another lab consult (IHC helps with this problem)

70
Q

limitation of IHC

A

lack of specificity to monoclonal Ab, esp. newly recogn agents

71
Q

IHC vs in-situ hybridization

A

same but doing IHC in-situ is potentially more sensitive and can identify low numbers of copies of the infectious agent nucleic acid

72
Q

RT-PCR also called

A

q (quantitative) PCR b/c can show if large load of agent if fluor earlier on

73
Q

these study pathogenesis, host-agent interaction and type animal pathogens (req. strict QC)

A

microarrays

74
Q

should use PCR on secretions in the water?

A

no- meaningless

75
Q

PCR vs. IHC, in-situ hybrid which is more accurate

A

IHC, in-situ and PCR as adjunct

76
Q

Definition of stillborn

A

Born dead at full term

77
Q

Definition of neonatal death

A

Death within the first 3 weeks after birth