Bovine Eye Diseases 2022 PDF

Diseases of the bovine eye. Robert Smith With credit to Dai Grove-White Learning objectives • Describe the aetiology, pathogenesis, clinical signs, pathology, post mortem findings, epidemiology, management and prevention of common opthalmological diseases of farm animal. • recognise eye lesions th...

Diseases of the bovine eye. Robert Smith With credit to Dai Grove-White Learning objectives • Describe the aetiology, pathogenesis, clinical signs, pathology, post mortem findings, epidemiology, management and prevention of common opthalmological diseases of farm animal. • recognise eye lesions that present in specific systemic disease states Eye lesions may present as: • Primary disease. • Secondary. • Indicator of a generalised disease state. Animal Blindness & Safety Examination of Eye in Adult Cattle • Restrain in a crush and tie head round to the side with a halter • Consider sedating if restraint is inadequate –(usually unnecessary) • Perform an auricopalpebral block - motor • Put an amethocaine in the eye? • Infiltrate local around the eyelids? • Look carefully – if you cannot see you do not know it is O.K. – keep on until you can be sure Primary disease. • Infectious bovine kerato-conjunctivitis - New Forest eye, pinkeye. • Bovine iritis - silage eye. • Squamous cell carcinoma - cancer eye. New Forest eye. • Caused by Morexella bovis. • Always ?? – Mycoplasma spp – Pneumonia viruses etc • Lachrymation • Blepharospasm. • Early keratitis - white spot. • Lachrymation. • Keratitis (fluorescin) . • Ulcer. • Early ulcer (fluorescin). • Ulcer & Descemet’s membrane. • Pannus - vascularisation. • Healing ulcer - vascularisation. Treatment. • LA eye ointment – cloxacillin every other day – (Opticlox, Orbenin Ophthalmic ointment ) • Sub - conjunctival injection – Oxytetracycline (Terramycin Q50 was licenced), amoxycillin, etc – on bulbar conjunctiva (best?) or intra-palpebral • Suture – 3rd eyelid & eyelids or eyelids only • Eye patches • Photophobia = keep in doors Risk factors. • • • • • • Flies. Woodland. Dust. Chaff. UV light. “virus pneumonia.” Prevention. • • • • Fly control - ear tags, pour-on, permethrins. Graze away from fly habitat (woodland). Ventilation & fly control inside. Vaccine - USA. Bovine Iritis - silage eye. • First reported in 1989 – Watson, Veterinary Record 124, 411 • Associated with big bale silage feeding • Winter Clinical signs. • • • • • Early cases - constricted pupil. Patchy or multiple areas of corneal opacity. Glaucoma. White flocules in anterior chamber. Later - vascularisation (inside surface of cornea). • “signs are on inside of cornea.” • Negative to fluorescin. • cf New Forest Disease. Pathology. • Uveitis. • Hypersensitivity reaction ?? • Anecdotal link with Listeria. • opacity. • constricted pupil. • early opacity. • “lesions on inside of eye.” • opacity. • vascularisation. • opacity. • vascularisation (internal) Treatment of bovine iritis • Antibiotics alone ineffective • Sub-conjunctival (bulbar) injection of – atropine (mydriatic) 0.3-0.6 mg ( 0.5-1 ml) – dexamethasone 1 - 3 mg (0.5-1.5 ml) – ± antibiotic • Treatment suggests hypersensitivity ? Injection site 22G needle (pale blue) Sub-bulbar conjunctiva Squamous cell carcinoma. • Breed disposition - Herefords. • Within breed susceptibility. • Older animals > 5 years old. • Related to UV exposure - Tropics. Squamous cell carcinoma. • Invasive - involving: – Cornea – Third eyelid – Conjunctiva • Remove - but may recur. • Removal from third eyelid. Enucleation • • • • • • • Eyes recover incredibly - so give time Some clients want you to get on with it! Prey animal – lost one side of vision Warn regarding care when handling! Same approach as small animals but bigger Sedation and local anaesthesia Retrobulbar / Petersen block? From G.B. Edwards In Practice March 2001 Foreign bodies in the eye. • Grass seeds, straw etc – outbreak reported due to “Barren brome” seeds - Vet Rec Sept 16th 2006 • Can lead to keratitis • Check carefully – use local anaesthesia • Remove – carefully! Foreign body. Foreign body in cornea. Trauma 10 days later – recurrent mild infections => cull “Secondary eye disease.” • Eye lesions as a feature of a specific disease Malignant Catarrhal fever. • Associated with sheep or Wildebeest. – Ovine Herpes Virus 2 • Usually isolated case. • Invariably fatal (?). • Serology - ELISA. Malignant Catarrhal fever. • • • • • • • “head and eye form” most common. Persistent pyrexia 41C. Depressed - encephalitis. Nasal & mouth erosions. lymph nodes enlarged. Respiratory signs. Diarrhoea. Eye lesions in MCF. • • • • Conjunctivitis Eyelid oedema. Blepharospasm. Corneal opacity - centripetal. • Early centripetal opacity. DDx – MCF vs Blue Tongue Virus • inflammation of the mucous membranes, congestion, swelling and haemorrhages. • Sheep are generally the worst affected • while cattle and goats do not usually show clinical signs • can carry the virus for a period of time Infectious bovine rhinotracheitis. BHV 1 - IBR • • • • • • Herpes virus Latent carriers (Trigeminal ganglion) Recrudescence (stress) Serology – ELISA Swabs – Immunofluorescence Vaccines – Intra-nasal or IM – Marker vaccine. Live and dead vaccine available. – Protection in face of outbreak Infectious bovine rhinotracheitis. BHV 1 - IBR • • • • • Pyrexia 41oC Conjunctivitis & serous discharge Corneal oedema Nasal lesions & discharge Severe milk drop Listeriosis. • • • • • • • • Infection via V or VII nerve to brain. Encephalitis. Circling disease. Unilateral facial paralysis. Depressed. Menace test – retraction Treatment – Oxytetracycline or penicillins 65% Recovery rate Facial paralysis - droopy ear. Facial paralysis. Dry eye keratitis. Generalised disease states in which eye lesions may feature. • BVD - cataracts. – May be ag +ve or –ve – May be ab +ve or –ve – Due to infection between d75 – 150 of pregnancy • Septicaemia - hypopyon. • Endotoxaemia- injected conjunctiva. BVD Cataract Cerebellar hypoplasia Lesions in animal developing immuno-competency – ag/ab reaction Micropthalmia. 3 calves from same farm - 2 with same sire BVD? Calf B Calf B Calf B Note “texture” of cataract • Calf A – Severe polar cataracts – Failure to detect BVD virus antigen by RT-PCR from the thymus – or by immunohistochemistry on brain tissue – Antibodies to BVD were detected in a pre-mortem blood sample suggesting maternal immunity • Calf B – – – – Retinal dysplasia cerebellum showed patchy mild granuloprival-type dysgenesis Suggestive of mid-gestational exposure to BVD virus Failure to detect BVD virus antigen by RT-PCR from the thymus – or by immunohistochemistry on brain tissue – Antibodies to BVD not detected in a pre-mortem blood sample suggesting either no maternal immunity to BVD or failure of passive antibody transfer • Given the variation in genetic background, BVD exposure and brain lesions seen in these two animals it is likely that neither genetics nor BVD virus are the major cause of the lesions observed in both individuals • Outbreaks of cataracts reported with the proportion of calves affected varying through the year and over subsequent years • Attributed to exposure to unidentified environmental factors with a suggestion that underlying genetics may modify response to the environment • Labs do not usually find BVDv in calves with cataracts! Sunken eye - dehydration. Systemic conditions Sunken eye (dehydration Petechiae – septicaemia/ endotoxaemia/ post-dystokia Sunken eye. Blood in anterior chamber e.g. bracken poisoning. Blindness. • CCN. • Lead poisoning. • Vitamin A deficiency. • Twin lamb disease - sheep only ! Cerebro cortical necrosis (CCN) • • • • • Thiamine (Vitamin B1) deficiency Young growing cattle/sheep Dietary change / high energy diet ? Thiaminase production in rumen Diagnosis - PME – brain fluoresces under u.v. light Signs of CCN. • • • • • Early cases - star gazing. -ve menace test - blind +ve pupillary response to light. Nystagmus & convulsions. Opistothonus. Treatment of CCN. • i.v. thiamine 5-10 mg/Kg - every 3-4 hours. – Vitamin B1 Inj (Bimeda) 100mg/ml – Combivit (Norbrook) 35 mg/ml – Multivitamin (Norbrook) 10 mg/ml • Advice re diet change • Monitor rest of group Lead poisoning. • • • • • • Any age - usually young cattle. Batteries, lead paint etc. -ve menace test. Dilated pupils. Tremors & convulsions. Treatment – Sodium Calcium Edetate (Animalcare) (EDTA) iv & sedation, magnesium. 25% diluted to 5% (50mg/ml) give 75mg/Kg i.v. daily in 4 equal doses for 2-5 days • Withdrawal periods – inform DVM re: lead in milk and meat • Diagnosis - Pb in kidney & history. • Walk the perimeter of the field to look for sources of lead Vitamin A deficiency • • • • • • Growing cattle indoors. Roots & straw diet. Night blindness. -ve menace test. Dilated pupils. Oedema of optic disk. Take home messages • • • • • Look carefully Restrain, sedate and Local A. Do not “leave things and see what happens” Individual as a sentinel for herd/flock Sheep not little cows always!