Abortion in sheep

1
Abortion in sheep

• N W Dyer
• NDSU Veterinary Diagnostic Laboratory

2
Preparing ewes for breeding season

• If possible put the ewes on a diet with higher
  nutrition
• They will release more ova to fertilize
• Deworm the ewes before breeding
• Use a product that will get tapeworms
• If possible vaccinate ewes
• Chlamydophila and Campylobacter
• Treat or cull lame or unhealthy ewes

3
Preparing ewes for breeding season

• Make plenty of salt available
• Iodized salt to prevent congenital goiters
• This is an infrequent cause of abortion
• Use additional selenium and vitamin E
• Selenium helps with iodine metabolism
• Helps prevent against white muscle disease
• Moist wool can mean fly strike

4
(No Transcript)
5
Preparing the ram for breeding season

• Make sure the ram is in good body condition
• Check the teeth for signs of wear
• Make sure the rams feet and legs are good
• Perform a breeding soundness exam on the ram
• Worm the ram
• Increase nutrition to the ram
• One ram per 30 to 40 ewes

6
Breeding time management

• Determine when you want the ewes to lamb and
  count back 147 days

7
Major infectious causes of sheep abortion in
North America

• Chlamydophila abortus
• Campylobacter spp.
• Toxoplasma gondii
• Various bacterial agents

8
Chlamydophila abortus

• Chlamydophila abortus is characterized by late
  term abortions stillbirths and weak lambs.
• Placentitis is present.
• Chlamydial organisms can be found by examination
  of appropriately stained smears of the placenta
  or vaginal discharge.
• Ewes seldom abort more than once but they remain
  persistently infected and shed C. abortus from
  their reproductive tract for 2-3 days before and
  after ovulation.
• Rams can be infected and transmit the organism
  through breeding.
• Control by isolating affected ewes and lambs and
  treating with long-acting tetracycline.
• Vaccines are effective in reducing abortions.

9
Chlamydophila abortus

• Pathogenesis
• Oral exposure leading to possible persistent
  infection of the intestine
• Shed by placenta fetus reproductive and
  respiratory discharges and feces
• During gestation the organism passes the
  intestinal barrier and invades the placenta
• Both fetus and placenta are infected

10
Chlamydophila abortus

• Serology
• Paired serum samples taken at the time of
  abortion and 3 weeks later should show a 4 fold
  increase in antibody titer
• Lesions
• Necrosis in fetal tissues
• Necrosis in placenta with characteristic
  cytoplasmic inclusions
• Elementary bodies seen with special stains

11
Electron micrograph of cell with chlamydial elemen
tary and reticulate bodies
Cell nucleus
12
Campylobacter spp.

• Infection with Campylobacter fetus fetus and C.
  jejuni results in late pregnancy abortions or
  stillbirths.
• Ewes may develop metritis and placentitis. The
  fetus is usually autolyzed and many have
  necrotic areas in the liver.
• Diagnosis relies on finding Campylobacter
  organisms in abomasal or placental smears or in
  uterine discharge.
• Strict hygiene is necessary to stop an outbreak.
  Use of tetracyclines may help prevent exposed
  ewes from aborting.
• Vaccination programs should be consistently
  practiced.

13
Campylobacter spp.

• Abortion rates range from 20 to 90
• Infected ewes recover and are immune
• Persistently infected ewes may shed the organism
  in feces
• Stillbirths weak lambs
• Infection is by ingestion

14
Campylobacter spp.

• There are sometimes prominent liver lesions
• Typical comma-shaped organisms may be in abomasal
  fluid
• Late abortions (last 6 weeks of gestation)
  premature births stillbirths weak lambs

15
The circle is around a group of
comma-shaped Campylobacter organisms. A
Diff-quick stain was used on a smear of abomasal
fluid
16
Note the areas of necrosis within this fetal
liver infected with Campylobacter.
Small intestine
Stomach
Lung
17
Campylobacter fetus bacterin

• Campylobacter fetus bacterin is given 2 weeks
  before breeding season and then again in 60 to 90
  days
• Ewes being vaccinated for the first time
• If the flock has a history of C. fetus abortions
  revaccinate the ewes in mid-gestation
• Use a killed vaccine

18
Toxoplasmosis

• Protozoan parasite which has the cat as a
  definitive host
• Infection is by ingestion of feed or water which
  has been contaminated by oocyst-laden cat feces
• Clinical signs range from fetal resorption to
  stillbirths and weak lambs depending upon the
  time of infection
• usually see 20 abortion

19
Toxoplasmosis

• Sometimes see necrosis and calcification of
  cotyledons
• The ewe does not become sick
• Antibody to protozoa may be detected in fetal
  fluids
• Submerge the placenta in isotonic salt solution
  and observe the necrosis of cotyledons

20
(No Transcript)
21
Toxoplasmosis not white areas of mineralization
and inflammation in the cotyledon.
22
Toxoplasmosis similar white areas are present in
this image.
23
Toxoplasmosis
24
The blue circle surrounds an area of
inflammation and the black circle surrounds
the Toxoplasma cyst (note the arrow).
25
This is aof liver tissue containing a
Toxplasma tissue cyst.
26
This is a similarof brain tissue
containing a Toxoplasma tissue cyst. The black
dots inside the cyst are a dormant form of the
parasite known as bradyzoites.
27
This is an image of a positive immunohistochemical
stain for T. gondii in brain tissue.
28
This image shows Several Toxoplasma tachyzoites.
This is the life stage responsible for clinical
disease. They measure about 3 microns in length.

29
Prevention

• Effective vaccination program
• Chlamydophila abortus 60 and 30 days before
  breeding
• Campylobacter spp. 30 days before breeding and
  in mid-gestation
• Feed a coccidiostat for Toxoplasma gondii
• Monensin (15 30 mg per head per day)
• Feed chlortetracycline
• 200 mg per head per day

30
Prevention

• Do not allow ground feeding or stagnant water
• Prevent contamination of feed and water with cat
  or bird feces
• Keep first lambing ewes separate
• Do not mix newly acquired or aborting ewes with
  pregnant ewes
• Avoid stress in the flock
• Dispose of placenta and aborted lambs

31
Therapy in an outbreak

• Get an accurate diagnosis
• 500 mg of chlortetracycline per head per day for
  5 days then reduce to 250 mg per head per day
• May need to give long-acting injectable
  tetracycline at 20 mg/kg per head subcutaneously
• Begin feeding coccidiostat - 15-30 mg per head
  per day

32
Therapy in an outbreak

• Isolate aborting ewes
• Discontinue ground feeding
• Check for sources of contamination
• For Salmonella abortions 5 mg per pound body
  weight of ampicillin for 3 days

33
Warning

• Most of these infectious agents are zoonotic
• Pregnant women should not be in the lambing area
• In particular Toxoplasma gondii can cause
  abortion and birth defects in humans

34
Management

• All new flock additions should be observed
• New pregnant ewes should be penned separately
• Feed 250 mg tetracycline per head per day
• Do not feed on ground
• Remove aborted fetuses immediately
• Consider vaccination

35
Bluetongue

• Orbivirus this is a vector borne virus
• Infection occurs in the first half of gestation
  resorption of fetus mummified fetuses
• Ewes do not show clinical disease
• Affects the fetal central nervous system
• Hydrancephaly cerebral cysts hydrocephalus
• Diagnose by serology or virus isolation
• The affected lambs are born months after mosquito
  season

36
Border disease

• Border disease is an important cause of embryonic
  and fetal deaths weak lambs and congenital
  abnormalities in sheep
• It is caused by a pestivirus.
• Abortion can occur at any stage of gestation.
  There are no clinical signs in the dam. Live
  infected fetuses may have congenital tremors and
  an abnormally hairy coat.
• Diagnosis is by identification of border disease
  virus or antibody in the placenta or fetal
  tissues.
• There are no vaccines available.

37
Cache Valley virus

• Cache Valley virus is a mosquito-transmitted
  cause of infertility abortions stillbirths and
  multiple congenital abnormalities in sheep.
• The most noticeable effects are stillborn lambs
  and the birth of live lambs with congenital
  abnormalities affecting the CNS and
  musculoskeletal system.
• At the time of abortion or birth the virus is
  usually no longer viable and diagnosis is by
  demonstration of antibodies in precolostral serum
  or body fluids.
• Vaccines are not available

38
This lamb has twisting of the spine or scoliosis
due to viral infection in utero
39
Another lamb from the same case shows twisting of
the rear limbs arthrogryposis and abnormalities
in the sternum.
40
Note the collapsed cerebral hemispheres
indicating Hydrocephalus.
41
Here the cerebral hemisphere has been opened to
show the dilated Ventricle.
42
Miscellaneous bacterial causes

• Listeria monocytogenes
• Leptospira interrogans
• Coxiella burnetti
• Salmonella spp.

43
Listeria abortions

• Listeria monocytogenes
• Third trimester abortion
• Focal necrosis in cotyledons and liver
• Diagnose by culture of fetal tissues
• Intestinal carriers shed the bacteria into
  environment
• Ewes may have a fever
• Ewes may have a retained placenta

44
Leptospira abortion

• Icterus hemoglobinuria anemia and fever in the
  ewe may precede abortion
• These tend to be late term abortions
• May see inflammation of fetal tissues
• Diagnose with a blood sample for serology urine
  sample from the ewe and fetal tissues and fluids

45
(No Transcript)
46
Coxiella abortion

• Caused by a bacteria Coxiella burnetti
• See late abortions and weak lambs
• Placentitis is present
• Isolation of C. burnetti from placenta
• Requires special technique
• The organism is inhaled or ingested
• Stress may reactivate an infection
• This is a zoonotic agent

47
Brucella spp.

• Late term abortions stillbirths weak lambs
• Placentitis hepatitis and pneumonia may be seen
  in the fetus
• Brucella organisms are zoonotic
• Isolate B. ovis from tissues
• Lung and abomasal contents

48
This placenta shows thickening and fibrin
deposits
49
Salmonella spp.

• Infection depends on stress on ewe and number of
  Salmonella ingested
• Usually in last month of gestation
• Ewes may develop diarrhea metritis peritonitis
  and septicemia
• Fetus and placenta appear autolyzed
• Fetus dies from septicemia
• Diagnosis is by culture of placenta fetus or
  uterine discharge

50
Salmonellosis
51
Iodine deficiency

• Sheep need 0.1 to 0.8 parts per million of iodine
  in their diet
• Usually acquire from feed water or soil
• Iodine can be trapped by dietary constituents
  called goitrogens
• Sheep need adequate selenium for proper iodine
  metabolism
• Cold stress can increase iodine requirements

52
Iodine deficiency

• Goiter or enlargement of the thyroid gland is
  seen in lambs
• It is an attempt by the body to compensate for
  insufficient thyroid hormones
• Most common in lambs born from a dam without any
  obvious signs of iodine deficiency

53
Iodine deficiency

• Impaired brain maturation in lambs
• Stillbirth
• Poor wool or hair coat
• Feed the ewes a fortified trace mineral salt
  based on iodized salt

54
Note the enlarged thyroid glands in this
stillborn lamb.
55
Fungal abortion in a lamb. Note the crusting on
the skin where fungi has colonized the epidermis.
56
Internet resources

• http//www.pipevet.com/articles/articles.htm
• http//www.merckvetmanual.com/mvm/index.jspcfile
  htm/bc/110305.htmwordovine2cabortion

57
(No Transcript)