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
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
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
Paired serum samples taken at the time of abortion and 3 weeks later should show a 4 fold increase in antibody titer
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
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
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.
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)
200 mg per head per day
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
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
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
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
43 Listeria abortions
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
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
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