Lecture 7

Question 1

What are the characteristics of bovine herpes virus 1?

Answer 1

-most frequently diagnosed viral cause of abortion in North American cattle
-up to 60% aborted during abortion storm
-localized to placental vessels
-fetus dead within 24 hours
-aborted tissues are uniformly dark red

Question 2

What are the consequences of BHV-1?

Answer 2

-last trimester abortions
-stillbirths
-weak calves
-placental retention
-necrotizing placentitis
-autolyzed fetus; necrosis with viral inclusion bodies

Question 3

Why is it important to avoid the modified live BHV-1 vaccine in pregnant cattle with no vaccination/challenge history?

Answer 3

the vaccine can cause these cattle to abort

Question 4

What are the characteristics of infectious pustular vulvovaginitis in cows?

Answer 4

-BHV-1 infection
-seen 1 to 3 days after mating
-vulvar pustules and temporary infertility
-lesions heal in 10 to 14 days

Question 5

What are the characteristics of infectious balanoposthitis in bulls?

Answer 5

-BHV-1 infection
-pustules on penis and prepuce
-refusal to breed
-severe infections can cause scarring
-lesions heal in 10 to 14 days
-preputial shedding contaminates semen

Question 6

What are the characteristics of intrauterine infection with BHV-1?

Answer 6

-severe, necrotizing endometritis
-resolves in 7 to 14 days

Question 7

What are the characteristics of oophoritis due to BHV-1?

Answer 7

-delays normal estrous cycle for 1 to 3 cycles
-no permanent damage to ovary
-ovary is not a site of virus reactivation
-want to give vx 1 to 2 months prior to breeding the first time it’s given to prevent vaccine-induced oophoritis

Question 8

What are the characteristics of BVDV?

Answer 8

-two genotypes; type 1 and type 2
-two biotypes; cytopathic and non-cytopathic
-can easily mutate from non-cytopathic to cytopathic
-enveloped; allows for easy environmental decontamination

Question 9

What are the consequences of BVDV infection during pregnancy?

Answer 9

-early embryonic death for first month or two
-abortion at any time during pregnancy
-immuno-tolerant PIs between days 70 and 150 gestation (non-cytopathic)
-congenital defects between days 100 and 150 gestation (but not PIs)
-normal/abnormal seropositive calves between day 150 and 285

Question 10

What are the two ways that PI calves are produced?

Answer 10

-non-PI pregnant female is infected with non-cytopathic BVDV during first half of gestation (90%)
-PI female becomes pregnant and births a calf (10%, always produces a PI)

Question 11

Why is PI testing important for the entire herd’s BVDV status?

Answer 11

if a calf is not a PI, it indicates that the mother cannot be a PI

Question 12

What is a common birth defect caused by BVDV?

Answer 12

cerebellar hypoplasia

Question 13

What are the testing options for BVDV?

Answer 13

-virus isolation (acute infection)
-PCR (acute infection)
-immunohistochemistry (old method)
-antigen-capture ELISA (new method for PIs)

Question 14

Why does antigen-capture ELISA only work for testing BVDV PIs?

Answer 14

the antigen burden must be high for an animal to test positive with this method; must be a PI to have a high enough antigen load

Question 15

Why should antigen-capture ELISA be run a second time on any animal that tests positive as a PI?

Answer 15

the test has a 50% positive predictive value; test should be run again to confirm the first result was not a false positive

Question 16

What are the characteristics of BVDV vaccines?

Answer 16

-over 147 available combinations
-want to use a vaccine that covers both genotypes (types 1 and 2)
-typically only contain cytopathic strains; can cause abortion but NOT a PI

Question 17

Which poisonous plants can cause abortions/repro signs in cattle?

Answer 17

-ponderosa pine
-locoweed
-lupine
-wild tobacco
-goldenrod
-sorghum
-cocklebur

Question 18

What are the characteristics of fungal causes of abortion?

Answer 18

-most commonly Aspergillus; can be Rhizopus, Mucor, or Absidia
-abortions occur in late second to mid third trimester
-marked multifocal placentitis
-fetus often has cutaneous lesions similar to ringworm

Question 19

What leads to poor diagnostic rates for abortion?

Answer 19

-inadequate or poorly preserved samples
-inadequate history
-non-infectious dz not being diagnosed
-infection of dam preceding abortion by several weeks; retrospective diagnostic effort

Question 20

What are the characteristics of history when determining cause of abortion?

Answer 20

-very important due to typical retrospective nature
-review of accurate records is often very helpful
-want to assess breeding management, vaccinations, stress, and diet

Question 21

Which samples are taken as “maternal samples” when determining cause of abortion?

Answer 21

-paired serum 3 weeks apart
-serum from herd mates
-routine samples from herd mates

Question 22

What are the characteristics of placental samples?

Answer 22

-most diagnostic sample
-include cotyledons
-consider maternal caruncle

Question 23

What are the characteristics of fetal samples?

Answer 23

-often not available due to predation
-fetal serum includes pericardial, pleural, or peritoneal fluid
-fluid should be negative for antibodies
-entire fetus should be placed on ice
-fetal parts suggested by the lab

Question 24

What are the indications for elective abortion in cattle?

Answer 24

-mis-mating/unintended pregnancy
-heifers entering feedlots
*should be done before 120 days gestation to avoid problems

Question 25

What are the methods for elective abortion?

Answer 25

-manual rupture of amniotic vesicle and uterine infusion of iodine products -luteolytic dose of PGF2alpha after 7 days of pregnancy

Question 26

What are the characteristics of using PGF2alpha to induce abortion?

Answer 26

-the earlier the injection is given, the less likely problems will occur -heat result in 2 to 5 days -expelled spontaneously; should recheck in 5 days

Question 27

What are the indications for induced parturition?

Answer 27

-labor and calf saving device (not a good idea) -maternal debility/prolonged gestation -hydrops -ET/cloning

Question 28

What are the precautions to consider with inducing parturition?

Answer 28

-breeding date of dam must be known -inducing 10+ days before calculated due date is associated with lower survival rate -due date cannot be predicted -infectious disease outbreaks may be a problem -most induced cows will have retained fetal membranes

Question 29

Which drugs are used to induce parturition?

Answer 29

-dexamethasone -PGF2alpha -both drugs together to narrow the calving window

Question 30

What are the characteristics of adventitial placentation?

Answer 30

-development of additional, typically diminutive cotyledonary attachments between placentomes (normal placentome range is 80 to 120) -represents a compensatory response to uterine damage or insufficient placentation

Question 31

What are the characteristics of fetal mummification?

Answer 31

-death in fetal stage in utero without bacterial putrefaction (closed cervix) -resorption of fetal fluids leaves dried skin/skeletal remains -preservation of CL; keeps cervix closed -rare in sheep/goats; infrequent in cows

Question 32

What are the treatment options for fetal mummification?

Answer 32

medical: -administration of PGF2alpha surgical: -should not be attempted in animals that have not had a previous normal pregnancy/delivery

Question 33

What are the characteristics of fetal maceration?

Answer 33

-death in fetal stage in utero with bacterial putrefaction -CL regresses in most cases -failure to deliver decomposing fetus -often left with "bits and pieces" of fetus -endometrial damage likely to be severe -treatment (PGF2alpha, colpotomy) often unsuccessful -poor reproductive prognosis; best to cull