Pathology of the Pregnant Genital Tract

Question 1

Define abortion

Answer 1

Premature expulsion of the products of conception from the uterus

Question 2

What causes the abortion of a fresh non-autolysed foetus?

Answer 2

Foetal stress

• Foetal/maternal illness
• Hyperthermia
• Increased foetal glucocorticoids

Question 3

What causes the abortion of an autolysed foetus?

Answer 3

Rapid foetal death

Loss of pregnancy by other mechanisms

Question 4

What can result in embryonic or foetal loss?

Answer 4

Failure of the zygote to attach to endometrium
Early embryonic losses
- Chromosomal abnormalities
- Inherited disorders
- Uterine factors
Late embryonic loss: after dam has recognised pregnancy
Foetal loss
- Placentitis => foetal ischaemia
- Foetal death from various causes
Stillbirth, in potentially viable stages of gestation

Question 5

What are the major features of embryonic death?

Answer 5

Zygotes and early embryos
15-30% loss normal
Expulsion or reabsorption
Return to oestrus at normal interval 
Often no diagnostic material available
Chromosomal abnormalities
Infections includ: tritrichomonas foetus, campylobcter spp. BVD

Question 6

What are the 3 major consequences of foetal death?

Answer 6

Abortion
Stillbirth
Retention of foetus or embryo
- Mummification
- Maceration (Autolysed)
- Emphysema

Question 7

What are the usual consequences of foetal death in uniparous organisms?

Answer 7

Death during early gestation results in mummification which ends with resorption.
Death in late pregnancy usually results in abortion

Question 8

What are the consequences of foetal death in multiparous organisms?

Answer 8

If most foetuses die it usually ends in abortion

If one, or only a few of the foetuses die, they are usually retained.

Question 9

Describe the process of mummification…

Answer 9

Mostly multiparous animals (sow)
No putrefying bacteria
Foetal skin is developed enough to withstand autolysis
Absorption of placenta and foetal fluids
No odour
Associated with closed cervix

NO ODOUR KEY

Question 10

Why do these species usually undergo mummification?

1. Horses
2. Sheep
3. Pigs
4. Canine

Answer 10

1. Twinning
2. Toxoplasmosis
3. Parvovirus
4. Canine herpesvirus

Question 11

Are mummified foetuses useful for diagnosis?

Answer 11

Diagnosis is usually not possible, but it doesn’t usually effect subsequent breeding

Question 12

Describe the process of maceration…

Answer 12

Foetus becomes liquified
Presence of uterine bacteria
Reabsorption or expulsion
Foetid odour
Common with Campylobacter and Tritrichomonas or non-specific
Consequence often endometritis or pyometra
Perforation of uterine wall by foetal bones possible leading to septic peritonitis

Question 13

Describe the process of foetal emphysema…

Answer 13

Putrefactive organisms ascending from the vagina
Open cervix
Mostly associated with dystocia
Putrefaction of foetus, distension with foul gas and crepitation
Advanced uterine lesions
Often fatal to dam due to toxaemia
SQ air in the lamb

Question 14

What are the major general causes of abortion?

Answer 14

Non-infectious

Infectious

Question 15

What are the estimated percentages of non-infectious causes of abortion in the UK?

1. Cattle
2. Sheep
3. Pigs
4. Horses

Answer 15

1. Cattle: 50%
2. Sheep: 40%
3. Pigs: 60-70%
4. Horses: 60-70%

Question 16

Describe the diagnostic rates of abortion in different livestock…

Answer 16

Sheep
46% diagnosis
70% are from placental examination
Investigate if 1-2% ewes aborting

Cattle
13% diagnosis
Very helpful is placenta submitted
Investigate if 3-5% cows or cluster

Pigs
12% diagnosis
Only investigate outbreaks

Question 17

Differentials for causes of ovine abortion

Answer 17

Chlamydia (42%)
Toxoplasma (22%)
Campylobacter (16%)
Salmonella spp (4%)
Listeria (3%)
Other (13%)

Question 18

Differentials for causes of bovine abortion

Answer 18

Neospora (25%)
Salmonella spp (14%)
Bacillus licheniformis (11%)
T.pyogenes (10%)
Listeria spp (4%)
Fungi (6%)
BVD (3%)
Campylobacter (4%)
Other (23%)

Question 19

Differentials for causes of equine abortion

Answer 19

Umbilical cord abnormality (37%)
Miscellaneous causes (28%)
EHV (19%)
Bacterial/fungal placentitis (16%)

Question 20

What should you consider when investigating abortions?

Answer 20

Zoonotic risk
Low diagnostic success
Maternal, foetal and placental factors
Look for foetal distress (meconium staining, in trachea or upper GI)
Look for degree of autolysis
Look if foetus and placenta appropriate size

Question 21

What are the protozoal causes of foetal loss?

Answer 21

Neospora canium

Toxoplasma gondii

Question 22

Describe the diagnosis of bacterial or fungal causes of abortion…

Answer 22

Culture of foetal stomach contents

Question 23

Describe the diagnosis of viral abortions…

Answer 23

PCR
Histopathology
Serology

Question 24

Characteristics of Neospora abortions?

Answer 24

Persistent infection in cattle
Repeat abortions rare
Dog is responsible for horizontal transmission
Vertical transmission is most common
Every calf of an infected dam will test positive

Question 25

How can you diagnose neospora canium?

Answer 25

PCR of brain stem

Histopathology of the heart or brain OR IHC

Question 26

What are the characteristics of Toxoplasma gondii?

Answer 26

In sheep and goats
Timing of infection is important
Transmitted by cat faeces
Strwaberry pip cotyledones with sites of multifocal necrosis

Question 27

How can you diagnose Toxoplasma gondii infection?

Answer 27

Foetal serology (IFAT) on free foetal fluids
Histopathology with IHC