Pathology of the Pregnant Genital Tract Flashcards
Define abortion
Premature expulsion of the products of conception from the uterus
What causes the abortion of a fresh non-autolysed foetus?
Foetal stress
- Foetal/maternal illness
- Hyperthermia
- Increased foetal glucocorticoids
What causes the abortion of an autolysed foetus?
Rapid foetal death
Loss of pregnancy by other mechanisms
What can result in embryonic or foetal loss?
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
What are the major features of embryonic death?
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
What are the 3 major consequences of foetal death?
Abortion Stillbirth Retention of foetus or embryo - Mummification - Maceration (Autolysed) - Emphysema
What are the usual consequences of foetal death in uniparous organisms?
Death during early gestation results in mummification which ends with resorption.
Death in late pregnancy usually results in abortion
What are the consequences of foetal death in multiparous organisms?
If most foetuses die it usually ends in abortion
If one, or only a few of the foetuses die, they are usually retained.
Describe the process of mummification…
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
Why do these species usually undergo mummification?
- Horses
- Sheep
- Pigs
- Canine
- Twinning
- Toxoplasmosis
- Parvovirus
- Canine herpesvirus
Are mummified foetuses useful for diagnosis?
Diagnosis is usually not possible, but it doesn’t usually effect subsequent breeding
Describe the process of maceration…
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
Describe the process of foetal emphysema…
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
What are the major general causes of abortion?
Non-infectious
Infectious
What are the estimated percentages of non-infectious causes of abortion in the UK?
- Cattle
- Sheep
- Pigs
- Horses
- Cattle: 50%
- Sheep: 40%
- Pigs: 60-70%
- Horses: 60-70%
Describe the diagnostic rates of abortion in different livestock…
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
Differentials for causes of ovine abortion
Chlamydia (42%) Toxoplasma (22%) Campylobacter (16%) Salmonella spp (4%) Listeria (3%) Other (13%)
Differentials for causes of bovine abortion
Neospora (25%) Salmonella spp (14%) Bacillus licheniformis (11%) T.pyogenes (10%) Listeria spp (4%) Fungi (6%) BVD (3%) Campylobacter (4%) Other (23%)
Differentials for causes of equine abortion
Umbilical cord abnormality (37%)
Miscellaneous causes (28%)
EHV (19%)
Bacterial/fungal placentitis (16%)
What should you consider when investigating abortions?
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
What are the protozoal causes of foetal loss?
Neospora canium
Toxoplasma gondii
Describe the diagnosis of bacterial or fungal causes of abortion…
Culture of foetal stomach contents
Describe the diagnosis of viral abortions…
PCR
Histopathology
Serology
Characteristics of Neospora abortions?
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
How can you diagnose neospora canium?
PCR of brain stem
Histopathology of the heart or brain OR IHC
What are the characteristics of Toxoplasma gondii?
In sheep and goats
Timing of infection is important
Transmitted by cat faeces
Strwaberry pip cotyledones with sites of multifocal necrosis
How can you diagnose Toxoplasma gondii infection?
Foetal serology (IFAT) on free foetal fluids Histopathology with IHC
