Production diseases Flashcards

Question

Pregnancy toxaemia in sheep - twin lamb

Answer 1

Pregnancy ketosis Usually occurs before lambing Can occur in beef Sheep peak energy demand is producing the lamb and colostrum at end of pregnancy not peak lactation - energy demands exceed supply Clinically indistinguishable from hypoCa - often one will precipitate other Off feed, dull, depressed, nervous (blindness), death Can be caused by teeth/lameness in sporadic cases Outbreaks - change in management - reduced DMI

Answer 2

Calcitonin = deals with blood calcium that’s too high Parathyroid hormone and vitamin D increase blood calcium Vitamin D and parathyroid hormone increases calcium uptake from the gut Parathyroid increases calcium release from bone and activates vitamin D Takes 1-2 days for parathyroid hormone effects to kick in

Answer 3

Increased with parity Less parathyroid receptors and less calcium stores Almost never see hypoCa in heifers as good calcium supplies and PTH receptors

Answer 4

Thrashing limbs and hyperaesthesia = hypomagnesemia Constipation and ruminal bloat = hypocalcaemia (muscles of rumen and GIT stop working) Sunken eyes and diarrhoea = toxic mastitis (toxins cause vasodilation and fluid leakage into the gut = dehydration); pyrexic initially then hypothermia Unable to weight-bear on one leg = nerve paralysis, broken leg -traumatic condition (can be secondary to milk fever but this is normally a generalised weakness, but milk fever could predispose/cause trauma)

Answer 5

Toxin causes flacid paralysis Looks like milk fever - down, constipated, rumen stops working Toxins produced by clostridia botulin growing in rotting organic matter Antibiotics dont help as toxin causes illness not bacteria Need to euthanase if nursing hasnt stopped progression No treatment

Answer 6

Skeletal muscle -weakness and S bend in neck Smooth muscle -GIT stasis and poor uterine involution Cardiac muscle -poor contractility and slightly increased heart rate (very increased in toxic mastitis)

Answer 7

400ml 40% calcium borogluconate slowly IV Monitor heart rate and rhythm Can cause dysrhythmias - slow down rate of calcium infusion if slight dysrhythmias Needs calcium so just hope it’s not a cow who’s heart will be affected Consider blood sample in case no response Take bloods initially and maybe don’t run them unless treatment hasn’t worked Outcome of treatment Eructation, defecation, standing If no response, consider alternatives and complications (e.g. “downer cow”) Should respond quite quickly Muscle, nerve or bone damage not uncommon if large cow has been down for a while

Answer 8

Calcium orally Well absorbed Required GI uptake Relatively easy Becoming more common Calcium subcutaneously Poor absorption due to peripheral vasoconstriction Not as effective as boluses and probably don’t last as long Easy Negative feedback Relatively common NSAID 700kg down cow is predisposed to secondary trauma complications Won’t do any harm and might help make it more comfortable and get up quicker Phosphorus If calcium is low then phosphorus is also often low - can mix in with calcium Common preparation of phosphorus isn’t biologically active so is just excreted Probably doesn’t have an effect *Phosphorus should recover anyway as calcium recovers if you just give calcium

Answer 9

Feed less calcium in the dry period so at the point they calve they have lots of parathyroid in their system Then switch quickly to a high calcium diet on the day they calve, allowing their bodies to utilise all available calcium Giving less sodium and potassium in the dry period reduces blood pH, which increases the efficacy of parathyroid hormone, but do have to feed calcium at the same time Pouring loads of salt onto their diet -taste disgusting so reduces feed intake and predisposes to ketosis

Answer 10

Maedi visna - lentivirus - Wasting, respiratory, neuro signs Ovine pulmonary adenocarcinoma (OPA) - Retrovirus - Weight loss, respiratory, sudden death Caseous lymphadenitis (CLA) - Corynebacterium pseudotuberculosis - Lymph node abscesses Ovine Johne's disease (OJD) - Mycobacterium avium paratuberculosis - Reduced ferility and weight loss Border disease (BD) - Pestivirus - Poor ewe fertility, hairy shaker/weak lambs and abortions

Answer 11

*Lentivirus– long incubation period (months to years) * Presentation variable, often chronic wasting and laboured breathing *Oronasal is the main route of transmission, but can also be spread through colostrum/milk and by fomites *Regional variation in prevalence (Leicestershire and Gloucestershire high) *Serological diagnosis (antibodies produced within weeks to months but tend to wax and wane) *No treatment or vaccine: control methods include purchasing from accredited flocks (or isolate and test), monitoring and culling positive animals (if practical) and reducing stocking density, preventing contact with neighbouring flocks. If high level of infection: 1. Cullflock & restock with accredited sheep 2. Try and reduce losses through management: a) Keep flock young b) Split into older & younger sheep for management c) Cull thin/suspect cases d) Run a less intensive system to reduce spread

Answer 12

*Retrovirus * Causes neoplastic proliferation of lung cells = adenocarcinoma, resulting in laboured breathing, increased respiratory rate, ill thrift and sudden death * Transmission mainly aerosol, but can be spread through milk and colostrum *Long incubation period – 6 months to several years No blood test commercially available for diagnosis; lung ultrasonography has been used but should be interpreted with caution; post-mortem the only definitive way to diagnose *No treatment or vaccine *Identify & cull infected & offspring – very difficult without test. Need to PM any sudden deaths/those showing ill thrift. * Manage in single age groups – keep young separate from adults *Reduce close contact – housing, stocking density, trough feeding. Need good hygiene *Snatch lambing & rear artificiall

Answer 13

*Corynebacterium pseudotuberculosis * Transmission through skin abrasion, inhalation or ingestion –often when sheep are grouped * Forms abscesses in lymph nodes with characteristic green pus, typically around head and neck (inguinal/scrotal in tups) * Diagnosis by bacteriology/serology *Bacteriology requires draining abscess *Serology has high specificity but low sensitivity Antibodies tend to wax and wane and presence of antibody doesn’t necessarily lead to disease. * Control methods include buying from trusted sources, boundary biosecurity and separating infected animals * Treatment with antibiotics not effective; vaccine not available in UK but can be imported on special licence (efficacy variable) *Zoonotic(although rarely reported in people)

Answer 14

*Mycobacterium avium spp. Paratuberculosis (MAP) * Causes inflammation in the gut and reduces metabolic efficiency, leading to reduced fertility and weight loss; don’t see scouring, but thin sheep/high flock culling rates/poor lamb performance *Cattle and sheep strains (C and S) – sheep susceptible to both (cattle fairly resistant to S strain) * Transmission mainly faeco-oral, but can be passed via milk/colostrum; lambs are infected early on in life (first 3-4m usually), but clinical signs are usually seen in animals over 2-3y * Diagnosis can be by serology, but antibody levels often remain low until clinical disease; faecal PCR – unclear how much bacteria correlates with disease; PME most definitive OJD control challenges - Low sensitivity of diagnostic tests - Inability to detect sub-clinical animals - Practicalities of testing entire flocks - Snatch lambing not practical - Contact between sheep and cattle - cograzing, slurry spraeding OJD control solutions - Lamb old/thin/high risk ewes away from rest of flock - Select replacements from younger ewes - younger less likely to be shedding - Cull low BCS - Maintain good hygiene and clean bedding - Vaccination - reduced shedding and clinical signs - not infection

Answer 15

* Caused by virus very similar to BVD in cattle (pestivirus); see hairy shaker lambs, poor ewe fertility, high levels of abortions or weak lambs * Proportion of UK flocks infected estimated to be between 30-38% * Transmission via respiratory secretions, transplacental, from dam to offspring during peri-parturient period, or via semen of PI rams * Intensive flocks at increased risk - transmission in extensive flocks appears to be moderate * Diagnosis by detection of antibody or antigen; as in cattle, PI animals will be negative for antibody (persistently), but will be positive for antigen Control - PI hunt not as practical as in cattle - BVD tag and test not valid for BD - Natural immunity through exposure of non pregnant animal to PI - but transmission can be slow - BVD vaccine - no evidence - Dont retain breeding females from lamb crops with affected cases/test all ewes to be retained (antigen test) - Optimise nutrition and parasite control

Answer 16

Biosecurity - most risk from animal movement Testing/accreditation Screen cull ewes and fallen stock - BD is exception - screening lambs more useful Screen bought in animals - ideally pre-purchase Quarantine - seperate from pregnant ones until after lambing - also for chlamydia

Answer 17

Reduced milk quality Decreased fertility Impaired immune function - metritis/RFM Role in other diseases - LDA

Answer 18

No change over dry period Max decrease of 0.5 between calving and peak lactation Aim for 2.5-3 at calving Avoid >3

Answer 19

Blood sample random selection at specific stages Usually transition (21-7d pre calving) and fresh calvers (10-25 DIM) BHB - ketone body, current energy supply demand, esp useful in fresh calvers NEFA - non esterified fatty acids - transport of fat, indicator of fat mobilisation Esp useful for transition 8-12 samples/group Target prevelance of high BHB/NEFA <10-20% Usually means any abnormal result suggests a problem >= 3/12 abnormal results taken to indicate herd problem

Answer 20

Poor DMI Excess BCS/overfeeding

Answer 21

Poor DMI Low ration energy density

Answer 22

Easy access trough space per cow Minimise impact of group changes Avoid overconditioned cows - esp at calving Maximise ration palatability Manage environment appropriately - temp, humidity, comfort

Answer 23

Dietary cation-anion balance Difference between concentrations of major cations (Na+, K+) and major anions (Cl-, S2-) in the diet I.e. it’s just a chemical property of a feedstuff or diet DCAB = ([Na+] + [K+]) – ([Cl+] + [S2-]) (all in mEq/kg DM) Diets with low DCAB (<0 mEq/kg DM) induce mild metabolic acidosis... Metabolic acidosis means... Enhanced uptake of Ca from the GI tract Ca mobilisation from bone Higher rate of vitamin D3 activation per unit PTH Increased target tissue sensitivity to PTH and activated vit D3 So the cow is able to mobilise Ca from body reserves more quickly True/full DCAB Aim for diet DCAB around 0 to -50 mEq/kg DM Often just by choosing lower DCAB feeds, may also use salts Usually doesn’t require Ca supplementation More common in lower yielding herds “Partial” DCAB Aim for diet DCAB around -100 mEq/kg DM Likely to require use of anionic salts (e.g. MgCl2, MgSO4) Usually needs Ca supplementation too Effective but more involved/ expensive

Answer 24

Calcium – requirements change depending on animal age and production status; nonlactating pregnant cows need 0.18% Ca of total DMI, and growing and finishing cattle need 0.31% Ca Phosphorus – works with calcium to form bone and used in DNA and energy metabolism; deficiencies involve decreased milk production, reduced weight gain, poor reproductive efficiency, etc.; calcium to phorphorus ratio should be 2:1 to 1.2:1 Magnesium – activates metabolic enzymes; low levels (e.g. lush grass in early Spring) cause grass tetany (urination, erratic behaviour, convulsions); need Magnesium to make up 0.04-0.1% of DMI Sodium and Chlorine – maintain volume, pH and osmolarity of body fluids; sodium used in muscle and nerve function; chlorine used for HCl in abomasum and CO2 transport; Na should be maximum 0.08% of DMI for dry cows and 0.1% for lactating cows; no known Cl deficiencies seen in cattle Potassium – deficiency causes nonspecific clinical signs of poor appetite, weight loss, performance drop and stiffness; need potassium levels of 0.6-0.7% of DMI; normally found in high enough quantities if plenty of roughage/silage fed Sulphur – in protein, some vitamins, enzymes, etc.; growing and finishing cattle should have 0.15% of DMI as sulphur; DMI sulphur over 0.4% is potentially toxic; excess sulphur interferes with selenium, copper, molybdenum and thamin metabolism; sulphur deficiency signs include increased feed uptake, unthrifty appearance, dull har and alopecia; excess sulphur signs include aimless wandering, blindness, muscle tremors and convulsions Cobalt – needed by ruminal bacteria to make vitamin B12; essential mineral; beef cattle need 0.00001% of total DMI; deficiency signs include loss of appetite, muscle wasting and anaemia Copper – deficiency signs include unthriftiness, bleaching of hair coat (spectacled eyes) and anaemia; need to be 0.001% of DMI in beef cattle; toxicity signs include haemolysis, haemoglobinuria and jaundice Fluoride – toxicity is the main issue and signs include abnormal bone structure and softening and irregular wear of teeth; safe levels for finishing cattle are no more than 0.01% of DMI and 0.004% of DMI for the breeding herd Iodine – essential to produce thyroxin; deficiency signs include a goiter, weak or hairless calves, reduced reproductive performance and retained placentas; needs to be 0.00005% of DMI Iron – used in oxidative enzyme systems and haemoglobin; needs to be 0.0005% of DMI; iron deficiency can occur in calves fed an exclusive milk diet, unless out at pasture; deficiency signs include reduced feed intake and pale mucous membranes; not really seen in adult cattle, but can be caused by extremely high levels of external parasites drinking blood Manganese – used in many enzyme systems; needs to be 0.0002% of DMI in growing cattle and 0.0004% of DMI in breeding cattle; high calcium and phosphorus levels interfere with manganese metabolism; deficiency signs include reduced fertility in cows and crooked calf syndrome in young calves Selenium – deficiency signs include white muscle disease (degeneration) and retained placentas; has similar metabolic activities to Vitamin E, so selenium requirement in diet depends on Vitamin E levels; beef cattle need about 0.00001% selenium of DMI Zinc – needed in enzymes for protein and carbohydrate metabolism and for immune function; maintenance requirement is 0.003% of DMI; lactation and reproduction requirements not known; deficiency signs include unthriftiness, excessive salivation, scabby skin on legs, slow wound healing, alopecia and dermatitis over the whole body; zinc supplementation not consistently beneficial

Answer 25

Copper Selenium Cobalt

Answer 26

Iodine Zinc Phosphorus Selenium Copper

Answer 27

Lead poisoning: neurological signs, commonly associated with access to a fairly obvious lead source (e.g. car batteries, old paint) · Copper poisoning: almost exclusively related to inappropriate or excessive supplementation - sheep are especially sensitive. Pig concentrate feeds can have high copper levels and can be a cause of toxicity in ruminants. Long-term exposure tends to accumulate within the animal (esp liver), followed by an acute haemolytic crisis - as this is often a group problem, one or two clinically severely affected animals may present initially but the rest of the group may be earlier in the "accumulation" phase.

Answer 28

<4 hours ideal More proximal better prog Vertical better prog Streak canal ideally not involved Superficial

Answer 29

Basal - Congenital in heifers - Chronic inflammation from infection in the dry period Mid teat - Chronic inflammation - Milk calculi - teat peas - Neoplasia - bovine papillomatosis - Congenital obstruction Apical - Fibrosis and stenosis of the streak canal due to chronic inflammation in heavy milkers Tight teat sphincter - Trauma to teat end creates scar tissue - leads to mastitis

Answer 30

Teat cistern infusion Infuse local anaesthetic via a teat cannula or syringe into the teat cistern Ring block Local anaesthetic into the full thickness of the teat in 4-6 sites around the teat base, with or without a torniquet; avoid entering teat canal and vessels Inverted V block Full thickness line block given over and adjacent to the affected tissue/incision Intravenous regional anaesthesia Torniquet around the teat and inject 5-7ml of local anaesthetic into any superficial vessel Line block Multiple subcutaneous injections of local anaesthetic 0.5-1cm apart Topical splash application Dripping or splashing local anaesthetic onto a wound and waiting 20 mins Paravertebral anaesthesia Anaesthesia to cranial udder and teats for standing surgery Lumbosacral epidural Anaesthesia of caudal abdominal wall up to the level of the umbilicus; temporary dysfunction of the hindlimbs, so need sedation and lateral recumbency

Answer 31

Mucosa Continuous sutures with vicryl Submucosa Continuous sutures with vicryl Skin Simple interrupted or horizontal mattress sutures with prolene

Answer 32

Bovine herpes mamillitis Mastitis - various organisms

Answer 33

Lacerations Photosensitisation Hyperkeratosis Udder oedema Ischaemic necrosis