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Flashcards in Bovine Deck (459)
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What type of mite is sarcoptes scabeiei?

Burrowing mite, lifecycle 10-17 days, direct contact spread or fomites, survival off animal only a few days.


What is the pathogenesis of photosensitization?

There is a photodynamic agent in the skin. Irradiation of the agent causes cell death, non pigmented areas without hair covering are most affected, causing necrosis and sloughing of skin.


Describe the difference between primary photosensitisation and secondary photosensitisation?

Primary - defective metabolism e.g porphyria, plant origin e.g st johns wort.
Secondary due to liver disease, failure to metabolise phylloerythrin (chlorophyll breakdown product) which builds up in circulation.


which type of fly are implicated in spread of summer mastitis?

Hydrotoea irritans


What type of flies cause blowfly strike?

Lucilia sericata or phormia terranovae. Less common than in sheep, larval infestation of soiled skin especialy in warm damp conditions eg adult cattle dehorned in summer.


What are the clinical signs of warble fly infestation?

Warble larval infestation by hypoderma bovis or H lineatum- subcutaneous nodules and cysts along the back of cattle in spring should be regarded with suspicion, confirmation obtained by carefully opening swellings.


What is the cause of infectious bovine keratoconjunctivitis? (New forest eye)

Moraxella bovis + IBR, mycoplasmas, flies, dust, uv light, moraxella perhaps found on normal conjunctiva and needs enhancing factors.


What are the clinical signs of new forest eye? (infectious bovine keratoconjunctivitis)

Uni or bilateral conjunctivitis, chaemosis, discharge, purulent, blepharospasm, photophobia, cornea - central white/cloudy raised lesion, oedema, after 6 days > vascularisation, mild anterior uveitis.


What is the treatment for infectious bovine keratoconjunctivitis?

Antimicrobial therapy with either topical clxacillin, chlortetracycline, or subconjunctival injection with 1.25ml procain penicillin or 1ml oxytetracycline, or systemic oxytetracycline LA, florfenicol or ceftiofur. In an outbreak - isolate affected cattle if possible.


What is silage eye? (listerial uveitis)

An opthalmitis believed to be associated with listeria monocytogenes is recognised in cattle and sheep related to the feeding of big bale silage from ring feeders. seen more commonly in cattle. Risk of direct ocular contact with the silage. consistent isolation of L monocytogenes from conjunctival swabs from affected animals.


What are the clinical signs of silage eye?

Lacrimation, blepharospasm, photophobia, swollen, folded iris, miosis. Within 2-3 days bluish white corneal opacity spreading centrally, white focal aggregations of fibrin in anterior chamber. In advanced cases - pannus and vascularisation. Very painful.


What is the treatment for listerial uveitis?

Response to topical treatments is poor. Subconjunctival injection of a combination of oxytetracycline and dexamethasone usually halts the progression of clinical signs when given in the acute stages of the disease. The eye will usually return to normal in a few days to a week, depending on initial severity of the problem. In sheep subconjunctival treatment is effective.


What is the causative agent of ovine infectious keratoconjunctivitis?

Mycoplasma conjunctivae - present in eyes for up to 3 months after recovery. More severe in ewes than lambs.


What are the clinical signs of ovine infectious keratoconjunctivitis?

Tear staining, blepharospasm, then progresses to stage 2 and cornea becomes cloudy due to keratitis, pannus and vascularisation spreads from limbus, very irritation. stage 3 - ocular discharge becomes more mucopurulent, may be shallow ulceration. stage 4- blind, corneal ulceration, anterior uveitis, anterior chamber may rupture resulting in permanent blindness.


How does ovine infectious keratoconjunctivitis occur?

Introduced by carriers, spread by close contact, in winter during feeding/yarding housing, wind and snow. in summer weaned lambs - high stocking rates, handling of the face and head whilst drenching, dust, long grass and flies.


What is the treatment for ovine infectious keratoconjunctivitis?

Tx recommended to prevent the risk of permanent blindness. Affected animals separated, ideally housed. Single i/m injection of long acting oxytetracycline is very effective in halting the development of clinical signs or curing in 4 days. Treatment of choice in a group of affected ewes. Topical application of aureomycin powder to the surface of the eye can be used in mild cases. Topical chlortetracycline repeated in intensive lambs.


Which type of urolithiasis is common in male sheep?

magnesium ammonium phosphate hexahydrate (struvite) calculi, associated with feeding concentrates high in phosphate and magnesium.


Where do calculi usually lodge in the sheep?

Lodge within the urethra just proximal to the sigmoid flexure or within the vermiform appendix.


What are the clinical signs of urolithiasis?

Frequent tail swishing and foot stomping. wide stance, stretching, dog sitting, tenesmus, painful bleating, teeth grinding, mm congested and HR and respiratory rate are increased. nil or only drops of blood tinged urine are voided.


What are the sequelae to a urinary blockage?

back pressure doesnt usually cause bladder rupture but urine leaks acros bladder wall resulting in uroperitoneum. rupture of urethra / penis commonly occurs in cases neglected after a few days with extensive subcutaneous swelling extending from the scrotum cranially to the prepuce.


How can urolithiasis be confirmed via laboratory tests?

BUN and creatinine can be increased by many times the normal range


What is the treatment for a urinary obstruction?

Blockage is relieved normally during clinical exam when the penis is extruded and vermiform appendix excised with production of a free flow of urine. Catheterisation of the urethra after excision of the vermiform appendix and back flushinng is rarely possible. Surgical correction of urolithiasis involves a sub ischial urethrostomy under caudal block but there are potential complications. Tube cystotomy has been reported to be succesful in some breeding rams but requires GA and placement of a foley catheter.


How can urinary calculi be prevented in rams?

Urine acidifiers such as ammonium chloride are commonly added to rations. sodium chloride has been added to rations to promote water intake. provision of roughage promotes saliva production and water intake. fresh clean water must always be available and frequent checks must be made for frozen pipes.


Describe urolithiasis in cattle when compared to sheep.

Partial/complete obstruction very uncommon in cattle. rupture of urethra more common than in sheep. Surgery in standing patient under low extardural block is more successful than shepe because hydronephrosis does not develop but is a salvage procedure only in cattle near slaughter weight.


How does pyelonephritis occur in cattle?

Occurs sporadically in cattle resulting from ascending infection with cystitis and ureteritis. more common in older beef cattle following an unassisted calving.


What is the common cause pyelonephritis in cattle?

Actinomyces renale


What are the clinical signs seen with pyelonephritis in cattle?

weight loss, poor appetite, fever, poor milk yield, cows calf fails to thrive. frequent attempts to urinate, flow rate is slower than normal , tail swishing with an arched back maintained for much longer than normal after urination. flecks of blood and pus are passed at end of voided urine. Grossly thickened ureters palpable on rectal examination. Dilation of renal calyces, echogenic flocculent material within the renal pelvis and renal enlargement are suggestive of pyelonephritis.


What is bacillary haemoglobinuria?

Causes sudden death in cattle and sheep caused by toxins of cl haemolyticum (cl novyi type D). focal anaerobic areas in liver caused by migrating liver flukes allow spores to germinate with release of toxin. Haemoglobinuria is rarely witnessed. If seen alive animals are isolated, arched back, febrile with rectal bleeding and bloody faeces. there is no effective treatment.


What is babesiosis in cattle?

Tick transmitted babesia bigemina and babesia bovis. Clinical signs o fever, depression, anorexia, pronounced tachycardia, tachypnoea, anaemia and haemoglobinuria manifest after 1-3 weeks. Death follows rapidly in untreated cattle. Treatment with imidocard.


What is a sandcrack?

loss of continuity of horn fibres of the palmar/plantar hoof wall extending for a variable distance from the coronet towards the bottom of the hoof wall. Sandcracks result from damage to the periople and underlying coronary band. There is often sudden onset of severe lameness when impacted material leads to pus formation and pressure on the sensitive laminae of the wall. Usually front feet are more often affected.