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The thin ewe - Coggle Diagram

- - - - may be a cause of lamb mortality from starvation or of depressed weaning weights of lambs
      - Peracute, gangrenous (usually due to Staphylococcus aureus), acute, subacute, and probably subclinical types occur.
      - The organisms most commonly involved are S aureus, coagulase-negative staphylococci, streptococci, Escherichia coli, Mannheimia haemolytica, and Trueperella (formerly Arcanobacterium) pyogenes.
    - - Signs of embolisation to other organs may also be seen and those of congestive heart failure (dyspnoea, poor pulses, pale mucous membranes, tacchycardia, pulmonary crackles)
      - sepsis
        
        pyrexia
        
        lameness
        
        neck pain
        
        lethargy
        
        anorexia
        
        weight loss
        
        epistaxis
      - A variable murmur depending upon the valve affected. It may be noted that murmur has recently arisen or changed. Other clinical examination findings include joint effusions, lymphadenopathy, pyrexia and in advanced cases signs associated with disseminated intravascular coagulopathy (D.I.C) such as bleeding diathesis and petechiation.
    - - long term prognosis is guarded to poor
  - - - weight loss and sometimes ascites only clinical finding
      - can mimic ovine johnes disease
- - - - Molar problems
        
        leads to mastication problems with fibrous feed
        
        impaction of food in cheek
        
        short jerky movements, with mouth slightly open when chewing
        
        excessive premolar and molar teeth wear
        
        leads to malocclusion and poor mastication of fibrous food
        
        very sharp enamel ridges develop on the outer aspect of the upper cheek teeth and the inner aspect of the lower cheek teeth, due to a lack of wear on these tooth margins
        
        examine molar teeth with a gag and torch
        
        cheek teeth loss can lead to unimpaired growth of the opposite tooth into this gap leading to a step mouth
        
        often have fibrous feed protruding from corner of mouth
        
        if severe often drop pelleted food or raise head whilst masticating
        
        There is no treatment and affected sheep should be culled although their body condition can be improved by 1.5 to 2 units of condition score following generous concentrate feeding (up to 1.5 kg daily) over a 10 to 12 week period which would command a much better slaughter price. Care must be taken to avoid problems with acidosis when concentrates are first introduced into the ration.
      - Normal
        
        Sheep have 32 permanent teeth. The temporary incisors erupt sequentially at approx. weekly intervals from birth. The temporary premolars erupt within 2 – 6 weeks. The permanent central pair of incisors erupts at 15 months and is in wear by 18 months; the other permanent incisors follow at 6 month intervals. The first permanent molar erupts at 3 and 5 months in the lower and upper jaws. The second permanent molar erupts at 9 – 12 months and the third permanent molar and permanent premolars erupt between 18 – 24 months.
      - Incisor problems
        
        premature loss or 'broken mouth'
        
        unable to bite short or rough pasture
        
        no recognised control measures
        
        management
        
        move to low ground pastures
        
        can be as productive as full mouthed ewes
        
        ensure
        
        appropriate sward height
        
        supplementary concentrate feeding
        
        assessment of incisor teeth alignment
        
        Run index finger along dental pad, with sheep's mouth closed and head held in normal resting position
        
        Prognathia
        
        overshot jaw
        
        common hereditary defect in blue face leicester
        
        brachygnathia
        
        undershot jaw
      - Dentigerous (odontogenic) cysts
        
        typically sheep aged 2-4
        
        Uniform, non-painful bony swelling of the mandibular symphysis about 5-6cm diameter, which involves the roots of the incisor teeth
        
        manage with preferential grazing and supplementary feeding
    - - Scald / interdigital dermatitis
        
        Individual cases of scald can be treated using antibiotic aerosol sprays. When several animals are affected, treating all sheep in the group in a 10% zinc sulphate solution or 3% formalin in a footbath usually provides effective control. Antibiotic footbaths are not justified.
        
        must stand in dry area after
        
        repeat weekly/every 2 weeks
      - foot rot
        
        oxytetracycline IM 10mg/kg
        
        remove debris from interdigital space + Ab spray
        
        foot bathing/formalin contraindicated as leads to pain and increased granuloma formation
        
        avoid foot trimming
        
        Dichelobacter nodosus.
      - contagious ovine digital dermatitis
        
        Affected sheep should be treated with parenteral long-acting oxytetracycline (10 mg/kg) and a NSAID, and skin lesions treated topically with oxytetracycline aeroso
      - toe granuloma
        
        e.g. excess trimming
      - shelly hoof
        
        When feet become overgrown through lack of wear, without infection, the wall and toe horn can become long and loose. This may not cause lameness.
      - white line disease/abscess
        
        Penetration of the white line - where the wall and the sole join - by stones or sharp objects causes white line disease. This can cause lameness and can become infected, progressing to a white line abscess which may progress right up the wall and burst out at the top of the foot.
    - - liver fluke
        
        acute fasciolosis
        
        late autumn and early winter
        
        associated with large numbers of immature flukes in the liver parenchyma
        
        acute haemorrhagic anaemia
        
        hypoalbuminaemia
        
        may be weak and pale and in some cases exhibit abdominal pain with a palpably enlarged liver
        
        subacute fasciolosis
        
        late autumn - early winter (like acute)
        
        acute haemorrhagic anaemic with eosinophilia and hypoalbuminaemia
        
        not as rapidly fatal as acute, affected sheep show clinical signs 1-2 weeks prior to death
        
        submandibular oedema (bottle jaw) may also be present
        
        chronic fasciolosis
        
        winter and early spring
        
        weight loss, anaemia, eosinophilia and hypoalbuminaemia and is due to the haematophagous activities of adult flukes in the bile duct
        
        severe cases
        
        submandibular oedema is prominent and terminal diarrhoea may occur
        
        clinical picture may be complicated with concurrent infections with ostertagia
        
        Diagnosis
        
        post mortem exam of fresh carcases = best
        
        Various serological techniques onl blood samples,
        including ELISA, can be usedto detect antibodies to
        F hepatica with a high level of specificity (over 90 per cent).
      - Haemonchus
        
        Hyper acute: death within 1w of heavy infection without significant signs
        
        acute: severe anaemia and generalised oedema
        
        chronic: anaemia, progressive weight loss
        
        tropical worm, needs warm weather
        
        FAMACHA
        
        Concern with resistance
        
        important to maintain some refugia
        
        distinguished on level anaemia
        
        target those with a clinically detrimental burden. Those with normal PCV are tolerating burden.
      - sheep scab
        
        psoroptes ovis
        
        live in skin surface, where their faeces cause an intense allergic reaction
        
        clinical cases often September - April
        
        can take 40-50 days after infection before signs are seen
        
        first visible signs
        
        restlessness
        
        rubbing against fence posts
        
        soiled and stained areas of wool
        
        head tossing and loose tags of fleece
        
        progresses to more aggressive itching e.g. clawing at flanks, biting and can lead to bleeding wounds and secondary skin infection
        
        Low birthweight and higher mortality occur in lambs born to ewes with sheep scab during pregnancy. Slaughterhouse condemnation of carcasses leads to further economic loss
        
        skin scrape from edge of crusting lesion and microscope examination
        
        if confirmed then all sheep in infected group must be treated
        
        mites may not be present in centre of lesion
        
        sheep can be blood tested for antibodies to sheep scab. The test will not return a positive result for at least two weeks after infection. It is only suitable to test purchased or returning animals which have been isolated for two weeks prior to sampling. Positive results confirm recent exposure to scab mites but the results will remain positive for several months even after effective treatment.
        
        Treatment
        
        Organophosphate dips
        
        only effective with correct plunge dipping
        
        kill mites in 24h and residual action for weeks
        
        will also control blowfly, lice, keds and ticks
        
        macrocyclic lactones
        
        moxidectin 1% or 2%
        
        doramectin
        
        ivermectin
        
        do not control blowfly, lice or ticks
        
        beware of meat withhold time
        
        beware of resistance (also common wormers)
        
        prevention: biosecurity, closed flock when possible.
      - parasitic gastroenteritis
        
        The most important of these are Haemonchus contortus, Teladorsagia (Ostertagia) circumcincta, Trichostrongylus axei, intestinal species of Trichostrongylus, Nematodirus spp, Bunostomum trigonocephalum, and Oesophagostomum columbianum. Cooperia curticei, Strongyloides papillosus, Trichuris ovis, and Chabertia ovina also may be pathogenic in sheep
    - - maedi visna
        
        non-oncogenic retrovirus
        
        long incubation period (several months - years) and become life long carriers
        
        Maedi
        
        chronic, progressive pneumonia in older sheep (typically over 3y/o)
        
        enlarged, heavy grey lungs with rib impression at PM
        
        visna
        
        neurological form of the disease
        
        can progress from unilateral conscious proprioceptive deficit in one hind limb to toe dragging and hindlimb paralysis
        
        Diagnosis
        
        flock screening or individual ewe with clinical respiratory signs
        
        select sample of ewes from highest risk group that are over 3y/o and have a low BCS
        
        high sensitivity ELISA blood or milk sample
        
        positive
        
        1 more item...
      - ovine johnes disease
        
        low BCS typically main presenting sign
        
        diarrhoea not usually a feature unless concurrent parasitism
        
        in agonal stages may be weak and unable to stand
        
        submandibular oedema (bottle jaw) only in extreme cases
        
        Lambs born to ewes in the terminal stages of Johne's disease have low birthweights (often as low as 2 to 3 kg), due to chronic intra-uterine growth retardation
        
        profound hypoalbuminaemia and normal globulin concentration (due to loss of albumin from damaged gut)
        
        more useful to evaluate weight loss in 10+ ewes than one detailed PM.
        
        often coincidentally have high parasitic faecal egg counts
        
        significant serological titres only in 60% if clinical paratuberculosis cases -> high false negative rate (low sensitivity) but specificity is high (greater than 95%).
        
        Vaccination offers the best long term prospect for control of Johne's disease in sheep flocks (approximately £2-3 per dose).
      - caseous lymphadenitis
        
        Corynebacterium pseudotuberculosis
        
        common sites of abscess development
        
        submandibular, parotid, pre scapular and pre femoral nodes
        
        if left open --> mature into open draining abscesses
        
        Internal
        
        Diagnosis
        
        PE of lesions associated with lymph nodes
        
        bacterial culture of suspected lesions
        
        serological testing
        
        treatment
        
        antimicrobial tx (systemic or intralesional)
        
        supportive care
        
        biosecurity
        
        not a curable disease - consider tx if emotional or genetic reasons and to limit infectivity to rest of herd
      - ovine pulmonary adenomatosis
        
        infectious neoplastic lung disease
        
        weight loss + respiratory distress + panting
        
        crackles
        
        coughing not prominent
        
        afebrile unless 2ry infection
        
        copious amounts of serous nasal discharge
        
        confined to lungs + rarely associated lymph nodes
        
        positive wheelbarrow test (care as causes considerable distress)