Sheep Flashcards
Outline the epidemiology of caseous lymphadenitis once an infected animal has been introduced into a herd of goats (4 marks). How would you first confirm the infection in the resident herd and then eliminate the infection from the herd (3 marks)? What biosecurity measures would you suggest for the future (3 marks)?
Once a carrier animal or fomite or infected animal (most commonly buck) is brought into flock, gradual increase in animals showing one or more abscesses, mainly around the head. Corynebacterium pseudotuburculosis. Gradually increases in waves to around 50% of flock. very infectious, mostly through contact with ruptured abscess material. Usual no clinical signs until lymph nodes in chest affected resulting in dyspnoea and chronic weight loss.
Pus is commonly creamy white or yellow compared to sheep where it is green, calcification is rare and concentric onion ring appearance seen in sheep is absent. Culture from abscesses.
Check for lymphadenopathy, shear from young to old, cull those affected, prevent entry, join an accreditation scheme.
Name 3 important gastrointestinal nematode parasites and 3 important external arthropod parasites which a farmer should consider when purchasing replacement ewes and rams (2 marks). Comment on biosecurity measures (4 marks) and treatments (4 marks) that could be used for replacement animals to minimize the impact of these parasites.
Nematodirus battus, haemonchus contortus, teladorsagia circumcinta.
Psorptes ovis, sarcoptes scabiei, hydroterea irritans.
Biosecurity - quarantine for at least a month on arrival, buy from a reputable source that has no history if the disease or is accredited as disease free, buy from one source, do not buy from a market, treat on arrival for ectoparasites, inspect carefully on arrival. Isolate any with signs, test faeces for eggs, monitor for signs of diarrhoea, serology can be possible.
Treatments - ectoparasites can use cypermethrin, certain forms can last up to 10weeks, diazinon lasts 8-10 weeks, however these have a longer meat withdrawal time. Dag to reduce soiling and or remove dirty wool,from the breech, avoid nutritional upsets which lead to diarrhoea, dock sheep at a young age, avoid breeding from susceptible sheep, dispose of carcasses quickly, reduce incidence of footrot.
For nematode worms, benzodiazepines but resistance reported, macrocytic lactones such as ivermectin and moxidectin, levimasole, closantel. Make sure you weigh and dose to the highest weight, calibrate and maintain equipment, drench and inject correctly, store drugs appropriately.
Suggest one general anaesthetic protocol and one local anaesthetic protocol for an exploratory laparotomy in a goat, giving advantages and disadvantages of each method (10 marks).
General anaesthetic considerations: cost is often a limiting factor, drug choice has to be careful as they are a food producing animal rumen is always full even though an 18-24 hour starvation period is recommended, but this means regurgitation and aspiration are potential complications. Rumen all tympany is a problem and will result in compromised respiratory and cardiac return. Saliva production is copious and aspiration and slipping are problems. Alpha 2s can result in pulmonary hypertension and hypoxaemia due to peripheral actions primarily. This is dose dependent but needs to be monitored.
Protocol - xylazine (care) and butorphanol (use under cascade), ketamine to induce but can make intubation difficult due to swallowing reflex retained, incubate and cuff the tube to prevent aspiration, maintain on isolation and use IPPV as hyper apnea quickly develops, blood pressure monitoring and oxygenation status, place stomach tube for tympany, clean airway on recovery and keep head down. Appropriate analgesia.
Advantages, monitor patient, recumbent, safer, analgesia present, easy surgical access etc.
disadvantages are mentioned in considerations above.
Local - Flank approach likely, local blocks needed, either para vertebral at t13/l1/l2, line or inverted l blocks. Sedate with xylazine beware action, only licensed one in cascade is procaine plus adrenaline, apply to skin and deeper layers. Leave time to work. Analgesia.
Advantages - cheaper, less intensive, can do standing, quicker recovery.
Disadvantages - less able to monitor, animal can go down, less control, less surgical site access.
Write brief, but specific, notes on the management of hypothermic lambs (10 marks).
Hypothermic lamb is defined as being less than 39C, actions vary depending on age.
37, give 100ml of warm colostrum, dry the lamb, and return to the ewe, recheck in half an hour ideally and monitor for suckling, if the ewe has enough milk etc.
- A flock of Scottish Blackface sheep running on improved upland grazing has had a number of lambs showing signs of ataxia at approximately 6 weeks of age. You suspect that this may be due to copper deficiency (delayed swayback).
a) What other differential diagnoses would you consider in this case? (10 marks)
b) How would you attempt to establish a definitive diagnosis of hypocuprosis? (10 marks)
c) How could you try to prevent hypocuprosis recurring in future lamb crops? (10 marks)
Differentials - delayed swayback, listeriosis, tetanus, tick pyaemia, louping ill, polioencephalomalacia due to Clostridium sporogenes or Bacillus thiaminolyticus, nephrosis, lead poisoning, hepatic encephalopathy. Hypoglycaemia. Border disease, cervical injuries, bacterial meningitis/encephalitis.
Diagnosis - history, clinical signs (normal at birth, onset at a few weeks old, hindlimb weakness and collapse, ataxia and paresis but can still suckle and graze), formalised brain and brain stem for histo pathology (can get myelination defects of the brain and spinal cord and even cavitation lesions in the cerebral white matter), copper status of pregnant sheep, other lambs or non pregnant sheep on the pasture. Test the soil for copper levels or molybdenum levels.
Prevention - treat with copper but beware toxicity, test soil and analyse levels dandy treat accordingly, monitor for signs of occurrence, do metabolic profiles of pregnant sheep before lambing period to see if copper is needed and give once at mid pregnancy a slow releasing injectable or oral preparation.
A lowland sheep flock of 500 ewes has over 10% of ewes in poor body condition (less than body condition score 2) prior to tupping. Describe how you would investigate the problem (10 marks) giving specific reasons for your actions. What factors may be causing this problem (10 marks) and what remedial measures would you suggest for each factor (10 marks)?
Have to consider what is causing it, is it a problem with appetite (food,quantity, quality), intake (palatability, trough space, bullying), weight loss (disease or disability).
Investigation - history around the above problems, including worming, lameness and specific disease history.
Clinical examination - look from afar, dental status, systemic parameters, diarrhoea, cleanliness, faecal score, wool condition.
Faecal samples - PCR or Elisa for different diseases, fwec.
Metabolic profiles - betahydroxybutyrate, albumin, urea nitrogen, magnesium and copper.
Serology for antibodies to diseases that can cause weight loss.
Feed analysis, observe feeding, dental examinations.
Factors - mentioned above, either decreased appetites due to food, quality or quantity; decreased intake due to palatability, trough space, bullying; or weight loss due to disease or disability.
Diseases include any disease of chronic duration such as scrapie, pulmonary adenomatosis, maedi-visna, chronic pasteurellosis, Johne’s, caseous lymphadenitis, parasites, ruminal impaction, foreign bodies, tumours, chronic lameness. Disabilities include lameness and teeth problems.
Remedial measures - feed analysis and improve quality or quantity depending on what deficiencies are missing and as such increase the appetite. Ensure enough trough spaces and enough space to prevent bullying. Test for diseases via serology and then take appropriate action, either cull infected, treat with appropriate medications, isolate infected and give time for recovery with better food, worm, ectoparasite treatment, dental examinations, lameness evaluations, breed animals with better parameters.
List 10 management or diagnostic practices that could be used to manage a goat herd which has a problem with Johnes Disease to minimize the spread of the infection (10 marks).
Faecal spread and infected generally in the first week of life.
1 Snatch kids at birth and feed artificially
2 don’t use pooled colostrum
3 routine faecal culture and PCR
4 regular cleaning and disinfection
5 bovine vaccine decreases disease
6 source replacements from clean herds
7 test all replacements into the herd
8 test all suspected animals and cull positives
9 cull herd and repopulate after intensive cleaning and disinfecting
10 test for anaemia, hypoproteinaemia, diarrhoea not usually a feature
A milking goat herd reports significant weight loss and poor milk yield in approximately 25 % of its milking goats. Describe briefly the stages in your investigation this problem, illustrating your answer by reference to specific factors or diseases that might be involved (10 marks).
Differentials - primary nutritional deficiency such as starvation, neglect, inexperience, trace element deficiencies.
Inability to use available foodstuffs - dentition, mouth lesions, lameness, blindness, bullying.
Unwillingness to use available foodstuffs - male goat at start of breeding season, unpalatable, food change.
Inability to increase feed intake to match production - peak lactation, pregnancy toxaemia, fatty liver syndrome.
Interference with absorption and loss of nutrients - GI parasitism, Johne’s, liver disease, chronic fascioliasis, abscesses, tumours, ragwort.
Pruritic conditions - lice, sarcoptes, scrapie.
Chronic disease presence - pneumonia, pasteurellosis, CAE, CLA, lungworm infestation, Johne’s, TB, tumours, CRF.
- Describe how you would attempt to eradicate Maedi Visna from a pedigree sheep flock, and prevent further cases from occurring in the future (10 marks).
Slaughter affected sheep.
Identify affected animals- clinical signs- over 3 years, weight loss exercise intolerance, dyspnoea, cough, no pyrexia unless 2o pasteurellosis. Can see chronic mastitis and arthritis.
Spread from goats with CAE (avoid contact), respiratory spread, colostrum and milk.
Do not breed from
Keep a young flock- cull older animals
Blood test for serology to check free status
There is a sheep and goat health scheme allowing monitoring and accreditation for free flocks. Only buy in stock from these accredited flocks and aim for free status.
- Describe how you would attempt to eradicate Maedi Visna from a pedigree sheep flock, and prevent further cases from occurring in the future (10 marks).
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- What are the indications for caesarean section in a ewe (5 marks)? How may you provide anaesthesia for this operation (5 marks)?
Maternal-fetal dysproportion that is unlikely to be delivered manually
Alive fetus, no obvious indication of infection
Ringwomb or other pelvic obstruction (including previous fracture) creating a barrier to natural birth.
Value of lambs- more likely to get alive fetuses in severe dystocia if done.
GA possible but requires more facilities and increased risk
Local anaesthesia- paravertebral, epidural, L block or line block.
- List the clinical signs that you might see in a case of pregnancy toxaemia in a ewe (5 marks). Describe briefly the ways in which you might attempt to treat a clinical case (5marks).
Clinical signs - abortion in last trimester, 48 hours or more following onset of clinical signs, encephalopathy resulting in depression and anorexia, apparent blindness, recumbency, coma and death.
Treatment - propylene glycol per os two times daily if anorexic only and then give high quality nutrition. No improvement or further signs give 100ml 40% glucose IV, combine with IVFT, induce abortion with dexamethasone, steroids also promote gluconeogenesis from the liver. Consider insulin, or calcium as well.
- You are approached by a client who wishes to establish a flock of pedigree Texel sheep. What advice would you give about biosecurity in purchasing and running such a flock? Illustrate your answer by referring to parasitic and other infectious diseases that are widely present in the national sheep flock. (30 marks)
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- You are approached by a client who wishes to establish a flock of pedigree Texel sheep. What advice would you give about biosecurity in purchasing and running such a flock? Illustrate your answer by referring to parasitic and other infectious diseases that are widely present in the national sheep flock. (30 marks)
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- What are the indications for caesarean section in a ewe (5 marks)? How may you provide anaesthesia for this operation (5 marks)?
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A farmer with a flock of over 500 mule ewes lambing in April requests assistance because he is losing too many lambs in the forst week of life. What are the possible causes of this problem? 10 Describe your approach to the diagnosis of the problem indicating any diagnostic tests you would carry out. 10 Draw up a generic action plan to reduce or prevent future losses. 10
Possible Causes:
Within hours - Hypothermia/hypoglycaemia
abortion/weak lamb causes- toxo, EAE, lepto, listerio, salmonella, campylobacter, brucella
nutritional- iodine deficiency,
Within days- swayback, septic e coli, diarrhoeic e coli,
- Describe briefly how you would treat and manage a ewe with post-partum uterine prolapse (10 marks).
Causes - poor uterine tone, increased post parturition straining, increased intra abd pressure, excessive traction, high oestrogen content of diet? Over conditioned animals? Excessive weight of RFM?
Tell farmer on phone to separate ewe and restrain to avoid trauma, wrap the uterus in a clean moist sheet. Give epidural, 2ml or procaine, ewe in sternal or lateral recumbency with hindquarters raised, assistant lifts tail and opens vulval lips. Remove gross contamination by gently washing with saline or mild antiseptic and place uterus onto clean sheet. Remove placenta if separates easily. Repair gross damage with absorbable sutures. Raise uterus above vulva and eased back in, body first massaged with flats of hands as very friable, and then the horns with lots of lubricant. Ensure horns are fully back in place, may need a wine bottle, and animal encouraged to rise. Give oxytocin, antibiotics, calcium and consider NSAIDS, treat shock if present. Good nursing, light diet and moderate exercise. Can amputate it.
- You are approached by a client who wishes to establish a flock of pedigree Texel sheep. What advice would you give about biosecurity in purchasing and running such a flock? Illustrate your answer by referring to parasitic and other infectious diseases that are widely present in the national sheep flock. (30 marks)
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What diseases cause neurological signs in a sheep? 4
What signs do they show? 4
Sudden Onset
Cerebro-cortical necrosis (blindness, opisthotonus, strabismus)
Hypocalcaemia (Stilted gait, muscle tremors, coma and death)
Hypoglycaemia/Pregnancy toxaemia (Depression, inappetance, blindness, recumbency, coma, death)
Hypomagnesaemia (Sudden incoordination and hyperaesthesia, sudden death)
Listeriosis (Head pressing, facial paralysis)
Louping Ill (Head pressing, jerky gait, leaping, staggering, circling, paralysis, fine tremors, nystagmus, lip nibbling)
Gradual Onset
Coenurosis, CNS abscess (Visual and postural deficits, circling, head aversion)
Scrapie (Incoordination, abn behaviour, weight loss, pruritis)
What can cause respiratory problems in:
a) Neonate (4)
b) Growing lambs (4)
c) Adults (5)
Neonate:
Individual: Trauma, neonatal respiratory distress, post dystocia oedema, inhalation (milk), congenital heart defects.
Multiple: M. haemolytica septicaemia, nutritional myopathy, cow colostrum anaemia.
Growing Lambs:
Individual: FB inhalation, Ilex choke.
Multiple: FB inhalation, Atypical pneumonia, Pasteurellosis, Parasitic bronchitis, nutritional myopathy.
Adults:
Individual: FB inhalation, Laryngeal chondritis.
Multiple: FB inhalation, Atypical pneumonia, Pasteurellosis, Parasitic bronchitis, nutritional myopathy, pulmonary adenomatosis, maedi-visna, nasal bots.
A farmer with a flock of over 500 mule ewes lambing in April requests assistance because he is losing too many lambs in the forst week of life. What are the possible causes of this problem? 10 Describe your approach to the diagnosis of the problem indicatng any diagnostic tests you would carry out. 10 Draw up a generic action plan to reduce or prevent future losses. 10
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Briefly describe how you would diagnose, treat and prevent pregnancy toxaemia in a ewe. 12
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OUtline the diagnosis and control of abortion caused by Toxoplasma gondii in sheep. 12
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- A lowland pedigree Texel sheep flock is experiencing losses of ewes due to mastitis prior to weaning.
a) Describe how you would manage an infected ewe
b) What measures would you consider to control the outbreak this year?
c) How could you prevent reoccurrence in subsequent years?
(30)
Manage an infected ewe- often progresses quickly to gangrenous mastritis and can be systemically ill. Abs (broad spectrum- oxytet) intramammary, parentally macrolides/TMPS/oxytet/fluroquinolones, NSAIDs, oral electrolytes, stripping, nursing care (feed, change recumbency) consider amputation/mastectomy. Take lambs off and bottle feed. If mild use intramammary cow tubes (7d withdrawl), wean abruptly, fly control, teat dipping.
This year- avoid flies (pour on sprays), consider parenteral treatment of ewes. Ensure good dry ewe therapy- using intramammary tubes, wean abruptly, improve hygiene. Monitor ewes closely and treat early. Cull ewes at end lactation and dont keep lambs for replacements. Create records.
Future years, avoid keeping triplets on ewes, crutch sheep, improve BCS, check for anatomical abnormalities, reduce stocking density, clean bedding, improve hygiene, avoid cross suckling, avoid lush clover pasture. Good dry ewe therapy and monitoring.
- A lowland pedigree Texel sheep flock is experiencing losses of ewes due to mastitis prior to weaning.
a) Describe how you would manage an infected ewe
b) What measures would you consider to control the outbreak this year?
c) How could you prevent reoccurrence in subsequent years?
(30)
Manage an infected ewe- often progresses quickly to gangrenous mastritis and can be systemically ill. Abs (broad spectrum- oxytet) intramammary, parentally macrolides/TMPS/oxytet/fluroquinolones, NSAIDs, oral electrolytes, stripping, nursing care (feed, change recumbency) consider amputation/mastectomy. Take lambs off and bottle feed. If mild use intramammary cow tubes (7d withdrawl), wean abruptly, fly control, teat dipping.
