Pregnancy Failure in the Mare

Question 1

Abortion warning signs

Answer 1

premature lactation
vulval relaxation
vaginal discharge

Question 2

List the main causes of abortion in the mare in the UK

Answer 2

EHV1
EHV4
placentitis
umbilical cord disorders
premature placental separation
placental abnormalities
twinning

Question 3

How do we prevent twinning ?

Answer 3

ultrasound guided manual separation of twin vesicles with the manual crushing of the smaller vesicle
should be done before day 15 (pre-fixation)
leads to 80% of remaining embryo survival
repeated rechecking until day 40 at least

Question 4

Describe how acute placentitis causes abortion

Answer 4

hyperaemia and haemorrhage leading to degeneration and necrosis from the chorionic villi to surrounding chorioallantois
organisms and toxins invade and kill the foetus

Question 5

Describe how chronic placentitis causes abortion

Answer 5

infection extends through placenta, leading to oedema and the thickening of the chorioallantois.
gradual separation of the affected chorionic villi

Question 6

Common bacterial causes of placentitis

Answer 6

Streptococci spp.
E. coli
Aspergillus spp.

Question 7

Diagnosis of placentitis ?

Answer 7

transrectal ultrasound
take a measurement of the combined thickness of the uterus and the placenta

can also test aborted foetal membranes

Question 8

Preventing placentitis methods ?

Answer 8

pre-breeding assessment of perineal conformation
endometrial swabs pre-breeding for problem pathogens
“caslick” operation post breeding

Question 9

EHV-1 CS

Answer 9

most common cause of infectious abortion in the UK
sudden, rapid abortion with no warning signs
respiratory signs

issue in the reactivation of a latent infection in young stock

Question 10

EHV-1 diagnosis ?

Answer 10

the foetus = excess serosal fluid, white spots on liver, enlarged spleen, soft thymus
the placenta = allantochorion thick and heavy, rupture across body
histology = necrotic foci in liver, lung and adrenal cortex, lymph tissue necrosis

also viral isolation from foetal tissues, PCR in 24hrs

Question 11

Prevention of EHV1 ?

Answer 11

vaccination available at (3), 5, 7 and 9 months into gestation

Question 12

EVA CS

Answer 12

systemic and resp disease
- pyrexia
- lethargy
- depression
- anorexia
- oedema of limbs and ventral abdomen
- conjunctivitis and chemosis
- nasal discharge

Question 13

EVA diagnosis ?

Answer 13

the foetus is autolysed with no specific lesions, can perform antibody titre

Question 14

EIA CS

Answer 14

asymptomatic mostly
sudden death after severe anaemia and decreased appetite common

Question 15

What should the vet see on post-partum placenta examination ?

Answer 15

F-shaped
complete ? (okay if tip of non-gravid horn detached)
cervical star intact