Lecture 4 and 5 Flashcards
What is the meaning of abortions in the first 3 months
No clinical sn
When do abortions most often occur
When ewes are yarded in late pregnancy - pregancy toxaemia
What are the common causes of abortion in Australian sheep
Campylobacter abortion, toxoplasmosis
Salmonellosis, listeriosis, ‘hair shaker’ disease
Is Campylobacteriosis zoonotic
Potentially
How is Campylobacter transmitted
By ingestion
- Contaminated pastures after ewe aborted
- Most ewes throw infection of in a couple of weeks, bye a small % carry bacteria for months
- Crows and magpies can carry bacteria after ingesting aborted foetuses
- Abortion occurs within 3 weeks of the ewe coming in contact with bacteria
- Aborting ewes develop good immunity and are unlikely to abort form this causes again
What are the clinical signs of Campylobacteriosis
- Abortion in mid to late pregnancy
- Still births
- Birth of premature lambs
- Most aborting ewes show no signs of sickness
- Ewes may retain foetal membranes and develop metritis
With Campylobacteriosis, what is seen in post mortem foetus
- Gross lesions variable and mostly non-specific
- Grey ‘rosette-like’ necrotic foci in foetal livers
How to control Campylobacteriosis
- Remove ewes from suspect areas or reduce stocking rates
- Hygiene precautions
- Antibiotics may be valuable if valuable stud animals are at risk of infection
How to prevent Campylobacteriosis
- Ewe joggers may be grazed on infected paddocks in order to infect them while non-pregnant
- Vaccination
What is the second most common cause for abortion in sheep
Toxoplasmosis
What are the clinical signs of toxoplasmosis
- Infected when not pregnant -> no clinical signs
- If infected in early pregnancy -> no clinical signs, foetal death and resorption
- If infected mid pregnancy -> still born or weak lamb, mummification, abortion
- Later part of pregnancy - offspring normal
What is the pathology of toxoplasmosis
Placental cotyledons: bright to dark red with white foci of necrosis,2-3 mm in diameter; intercotyledonary areas
Mummufied foetus
Where to take samples for histology if expected toxoplasmosis
Placental cotyledons, foetal brain, liver, lung
How to control toxoplasmosis
Hygiene
Treatment of valuable ewes
Graze young stock on areas likely to be contaminated with cat faeces
Vaccination
Chemoprophylaxis
Is salmonellosis zoonotic
Yes
How is salmonellosis transmitted
Ingestion
Clinical signs of salmonellosis
- Mortalities
- Diarrhoea
- Foetal death, abortions
- Retained foetal membranes, septicaemia, high fever
How to diagnose salmonellosis
Isolation of organism from foetal stomach and placenta
How to treat and control salmonellosis
- Separate affected animals from unaffected animals, reduce stocking rates, avoid further stresses
- Possible antibiotics for affected animals and supportive therapy
- No vaccine in Australia
How does onion grass poisoning occur
Ingestion of plants or fungus infesting the plant can cause abortions and infertility and staggers
When do ewes lose their lambs due to onion poisoning
Early or mid-pregnancy
How to prevent onion grass poisoning
Pasture renovation
Characteristics of listeriosis
Bacteria survive for long periods in soil and on decaying vegetation and can be present in gut of normal sheep
When does abortion occur with listeriosis
Combination of stressful conditions are present -> weakens ewe’s immunity -> bacteraemia -> bacteria in foetus and foetal membranes
What are the clinical signs of listeriosis
- Abortion at any stage of pregnancy
- Still births
- Aborting ewes show generally no signs of ill health, occasionally development of reddish brown discharge after aborting
What would you see doing a PM with listeriosis
- Rapid autolysis
- Multiple yellow-white foci, less than 2mm in diameter, in foetal liver
Prevention of listeriosis
Fedd good quality silage
What is border disease
Hairy shaker disease
How is ovine pestivirus trasnmitted
Mucous membranes
- Close contact needed
- Some sheep do not throw off the virus
- ‘Hairy shaker’ lambs that survive are especially likely to become carriers
- Virus cannot survive on pastures for more than a few days
What are the clinical signs of ovine pestivirus
- If infected when not pregnant - may develop mild fever, develop immunity
- If infected before D50 - foetal death: resorption, abortion, aborting ewes show no signs of sickness
If infected during between D50-80 - outcome variable - Foetal death and abortion
- Birth of dead or live lambs with hairy coats and varying degrees hypomyelinogenesis, cerebellar and cerebral dysgenesis, arthrogeryposis, kyphosis, brachygnathia - persistently infected with virus; no antibody detectable
- If infected after D85: foetal death rare, weak or normal lambs with antibody to virus; no virus detectable
Diagnosis of ovine pestivirus
- Clinical signs/pathology
- Virus isolation
- Histopathology foetal nervous system
How to control ovine pestivirus
- Identification and removal of carrier animals
- Slaughter this year’s lamb crop
- In endemically infected flocks, expose breeding animals early in life when not pregnant
How to prevent ovine pestivirus
Maintain a closed herd, vaccination
What are asymptomatic carriers of coxiella brunetti
Sheep, goats, cattle
What can Q-fever cause in sheep and goats
Abortions and birth of stillborn and weak, live lambs
How to diagnose coxiella brunetti
Identification of agent, serology
Is coxiella brunetti zoonotic
Yes
How is coxiella brunetti transmitted
Infection is transmitted by inhalation of aerosols or dust contaminated with coxiella brunetti from infected sheep/goat or through direct contact with infected animals, their birth products or the
What are the clinical signs of Q-fever: Acute form
- Incubation period 14-21 days
- Fever, chills, sweat. headache, muscle pain, painful joints, fatigue, nausea, aversion to light, weight loss
- Without treatment, recurrent bouts of disease possible
- Respond all on ab treatment
What are the clinical signs of Q-fever: Chronic form
- Occasionally, chronic Q-fever with possible complications such as endocarditis
- Requires prolonged ab treatment
- Placentitis
How to prevent Q-fever in humans
- Vaccination
- Personal hygiene when handling foetal membranes or aborted foetus
What are the clinical signs of enzootic abortion of ewes
- Abortion in last 3 weeks of pregnancy
- Stillborn lambs and weak lambs
- Can affect up to 30% of ewes in previously uninfected flocks
- Subclinical
- Respiratory infection
- Pregnant women: abortion, stillbirth
What is the epidemiology of enzootic abortion of ewes
- Major source of infection is infected placenta and uterine discharge of aborting
- Transmission of infection is via ingestion or inhalation of contaminated dust or fluid droplets
- Infection during late pregnancy will lead to latent infections and ewe will abort in next pregnancy
-Ewe lamb also can acquire latent infection and will abort during their first pregnancy - Aborting ewes remain chronically infected but do not abort again
- Humans can become infected by handling infects placentas or dead lambs
How do diagnose enzoonotic abortion of ewes
History, CS, post-mortem, identification of agent
How to control enzoonotic abortion of ewes
- Hygiene measures, ewes usually immune after abortion
- Vaccine available overseas
What is the epidemiology of Schmallenberg virus
- Transmission of infection by insect vector then vertically in utero
- Incubation period 1-4 days
- Short viaemic period
What does pregnancy toxaemia cause
Lambing sickness, twin lambing disease
Explain the process of pregnancy toxaemia
Late pregnancy -> very high energy requirements -> often exceed what is available in feed -> utilise body reserves -> loss of condition ->metabolic overload
What are the clinical signs of pregnancy toxaemia
Dullness, loss of appetite, lags behind the mob when driven -> separation from the group, does not respond when approached, appear blind, if forced to move will stagger and stumble and go down -> Ewe will become recumbent, may stargaze, sink in a coma and die -> clinical signs usually progress over a period of 2-7 days
What would you see PM with pregnancy toxaemia
- Uterus usually contains two or more developed foetuses
- Liver is pale, fatty, swollen and quiet soft
- The adrenal glands may be enlarged
- Histopathology - liver/brain
Clinical pathology of pregnancy toxaemia
Hypoglycaemia
Ketonemie/ketonurie
Treatment for pregnancy toxaemia
Glucose therapy/fluid therapy
Cortocosteroids
Caesarian section
Prevention of pregnancy toxaemia
- Match energy requirements with feed
- Monitor body weird and condition score
- Target CS of 3-3.5
- Supplementary feed if needed
- Keep handling and holding of feed in late pregnancy to minimum
- Cull ewes with broken mouths
Clinical signs of pregnancy toxaemia in goats
Lose appetite, become dull and wander aimlessly, go down, sink into coma and die
What triggers hyocalcaemia
Stress factor - sided reduction in calcium intake - ewes on lush pastures or oat crops in later winter after drought
- Low dietary calcium intake and depletion bone reserves from grain feeding during preceding months
Clinical signs go hypocalcaemia
Initially affected ewes become isolated and have a stiff gait with muscle tremors
Soon ewes become weak and remain recumbent, often ‘head to flank’ sternal recumbency, struggle when handled, but unable to get up
How to treat hypocalcaemia
Calcium borogluconate - 50ml 40% solution IV or SC
How to prevent hypocalcaemia
- Avoid stress in late pregnancy or early lactation
- Keep time in yards to a minimum
- Add 1.5% lime stone as calcium supplement when feeding grain
- Avoid access to plant high in oxalates
What does hypomagneseia cause
Grass tetany; occurs where cerebrospinal fluid Mg levels fall below normal
What is hypomagnesemia often complicated by
Low blood Ca levels
What causes hypomagnesemia
Lush grass dominant pastures or rapidly growing fodder crops during late winter are low in Mg and pose a grass tetany risk
Mg is actively absorbed through rumen wall and can be affected by other factors, such as potassium concentrate
What are the clinical signs of hypomagnesemia
Often found death in paddock
Ataxia, muscle tremors, titanic signs
Collapse, convulsions and sever limb paddling, forth at mouth
Death within 4-6 horse
Treatment of hypomagnesemia
ASAP
Magnesium + calcium IV/SC therapy followed by SC magnesium salts
Relapse possible, keep under farmer observation, retreat if necessary
Prevention of hypomagnesemia
Keep tree handling to minimum in first weeks of lactation
Provide hay and water if yarded overnight
Hay with magnesium oxide
