Problems with pregnancy in the mare Flashcards
Up to what day is a conceptus termed an embryo?
40 days of gestation
What are the 8 causes of embryonic loss in mares?
Endocrine Oviductal environment Genetic abnormalities Uterine environment Maternal age Insemination over 6 hours post ovulation Site of intrauterine fixation Malnutrition
What are some ultrasound signs of early embryonic loss?
Irregular shape of vesicle Prolonged mobility of vesicle over day 16 Excessive endometrial oedema Fluid within uterine lumen Undersized embryo for age Loss of heartbeat Decrease in fluid surrounding embryo Increased echogenicity of fluid within the conceptus
If by what day after conception should you terminate a pregnancy if there is no heart beat?
Day 30
- Use PGF2alpha
- Before endometrial cups form
What days should you do serial examinations after conception to detect a problem with the embryo?
Days 12-60
What is uterine body pregnancy?
Embryo becomes fixed in the uterine body rather than at the base of a uterine horn
Why does pregnancy loss occur in uterine body pregnancy?
Placental insufficiency, retarded foetal growth
Abortion late in gestation
Rare
What is hydrops?
Excessive accumulation of foetal fluids within the foetal membranes
What is hydrops amnion?
Foetal problem, increased fluid amnion
What is hydrops allantois?
Placental problem, increased fluid allantois
Is more common
Over 7 months gestation
What are clinical signs of hydrops?
Enlarged abdomen Rectal palpation feel enlarged uterus, foetus may not be palpable Depression Anorexia Abdominal pain Ventral oedema Reluctance to move and difficulty moving Tachypnoea and dyspnoea
How do you treat hydrops?
Induce abortion as foetus usually non-viable
Pre-treat mare with IV fluids and gradual siphoning of fluid via transcervical catheter
Assist birth to avoid dystocia
Supportive treatment to manage any complications associated with retained placenta, metritis, laminitis
Is unlikely to recur in the future
What is the cause and predisposing factors of ventral abdominal ruptures?
Rupture of prepubic tendon, rectus abdominus muscle or hernia
Factors - Older mares, twins, hydrops allantois, draught breeds, trauma
What are clinical signs of ventral abdominal rupture?
Ventral swelling Oedema Abdominal pain Recumbency Swelling of udder Saw horse stance Subcutaneous haemorrhage Cold abdominal skin
How do you treat a mare with a ventral abdominal rupture?
Poor prognosis
Either aim to save the mare or the foal
Save mare by inducing parturition
Save foal by applying support wraps and nursing until parturition can be induced
If medical management cannot be undertaken then euthanasia
What is luteal insufficiency?
When luteolysis or inadequate concentrations of P4 occur up to days 80-120
Result in pregnancy loss
How do you treat luteal insufficiency?
Altrenogest orally daily
Daily injections of progesterone in oil
Microencapsulated formulations every 7 days - USA
-Treat until the placenta can produce enough progesterone by itself - Day 150 to be safe
In a pregnant mare what is the minimum progesterone concentration?
4.0 ng/mL
What should you do if you detect a twin pregnancy?
Crush/pinch one
Terminate pregnancy and recycle mare
If unilateral may leave and monitor, hopefully will naturally get rid of one
What can you give prophylactically to manual twin reduction?
Lignocaine to relax tone of rectum
-Afterwards can give NSAIDs and progesterone
What is the normal gestation length for a mare?
340 days
Under what gestation length is it considered to be an abortion?
Under 300 days
What do you need to examine after an abortion of the foetus and placenta?
Placenta and umbilical cord
Weigh them
Assess foetal size, crown-rump length, autolysis
Small foetus suggests growth retardation from chronic placental disease
Foetus of normal size suggests acute abortion
If an abortion was caused by an anscending infection, what will you see on the placenta?
Thickened area extending from the cervical star
What is a ‘red-bag’ and what causes it?
Dramatic colour difference of tissues (chorioallantois) that were prematurely separated
-Premature placental separation
What samples should you collect from an aborted dam?
Uterine swab
Serum samples -One right now, another in 2-3 weeks
What are some management strategies if an abortion was potentially caused by an infectious agent?
Isolate aborting mare/s
Isolate and monitor in-contact mares
Separate in-contact mares into smaller groups
Quarantine affected pasture
Do you need EHV-1 vaccine?
Control and quarantine any introduced horses and advise restricting departures from property
Is EHV-1 contagious and/or notifiable?
Yes to both
- Highly contagious
- Notifiable
What does EHV-1 cause?
Respiratory disease
Neurological disease
Abortion
Neonatal deaths
How is EHV-1 transmitted?
Ingestion or inhalation
How long does EHV-1 survive in the environment?
14-42 days
What is the incubation period for EHV-1?
Highly variable
Abortions can occur 1-4 months after infection
When does abortion occur from EHV-1?
Mid-term to late gestation
5 months+
-But rare for a mare to abort again from EHV-1
What is the role of latency with EHV-1 infection?
Latently infected horses can become reactivated and nasal shed
Then infect young horses and pregnant mares
What are clinical signs of an EHV-1 infection?
No maternal illness usually Foetus -Fresh or autolysed -Placenta may be attached - +/- pulmonary oedema, hydrothorax
How do you diagnose an EHV-1 infection?
Fluorescent antibody test
Virus isolation
PCR
Histopathology for intranuclear inclusions
What is the vaccination protocol for EHV-1?
Pregnant mares at 5, 7, 9 months
How do you manage and control an outbreak of EHV-1?
Place aborting mare/s in isolation - leave in paddock where aborted and move other horses
Dispose foetus and membranes and clean contaminated area
Suspect EHV-1 until proven otherwise
Prevent the spread
In contact pregnant mares should be isolated until 30 days post-foaling
If positive for EHV-1 split in-contact mares into smaller groups
The environment is ‘clean’ again after 21 days with no horses on it
What is the situation with Equine viral arteritis in Australia?
Notifiable disease
Present in Australia but low virulence strains
Disease associated with infection not yet recorded here
What are clinical signs of Equine viral arteritis?
Generalised or subclinical maternal respiratory disease Vasculitis Generalised oedema Haemorrhage Abortion at 5-10 months
What is the most common cause of abortion in mares?
Bacterial placentitis?
What are the 2 routes of infection for bacterial causes of abortion?
Transcervical - ascending
Haematogenous
What is the most common bacterial cause of abortion in mares?
Streptococcus zooepidemicus
Less than 200 days gestation
What is the second most common bacterial cause of abortion in mares?
Escherichia coli
Over 200 days gestation
What are signs that nocardioform placentitis has caused an abortion?
In 3rd trimester
Or if early, will be small and weak usually
Usually sporadic
Restricted to placentitis
-Affected chorion has thick, brown exudate
Foetal tissues not infected