Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Cattle II > Ocular diseases > Flashcards

Ocular diseases Flashcards

(80 cards)

Start Studying
1
Q

How to provide eyelid akinesia

A

Auriculopalpabral nerve block

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Local anaesthesia of the eyelid

A

May be necessary when procedures that touch the eyelids are to be performed, so the animal does not feel the instruments in contact with the eyelid

5 to 10 ml of local anaesthetic is instilled into the eyelid margin

Also, it helps to decrease stress caused by touch during examination of the eye.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Complete ophthalmic examination

A

General assessment
- size and position of globe
- vestibular eye reflexes in both eyes

Schirmer tear test (unless visible moisture)

Retropulsion of the globes with closed eyes and then with open eyelids - to detect masses, inflammation etc.

Brief cranial nerve exam
- palpebral
- menace
- PLR

Fluoroscein test

Topical anaesthetic and intraocular pressure measurement

Intraocular structures examination

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What can cause a deficit in the palpebral reflex?

A

Sensation deficit associated with trigeminal (CN V)

Motor deficit associated with facial nerve (CN VII) - assess ear position, and lip and cheek tone

Both

Calves with elevated D-lactate have reduced palpaebral reflex, likely caused by skeletal muscle weakness

Neonatal calves have absent palpebral in first week of life

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What does the menace response assess?

A

Assesses vision

Sensory is optic nerve (CN II)

Motor is facial nerve (CNVII)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Normal cattle pupils

A

Horizontal ellipse with small brown protuberances in the dorsal and ventral central margins - corpora nigra

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Relation between PLR and blindness

A

Absent PLR with blindness usually is related with retina, optic nerve, optic chiasm or proximal optic tract diseases;

Normal PLR and blindness are mostly cause by cerebrocortical disease (central blindness);

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Prepatation for ocular surgery

A

Prep with e.g. povidine-iodine solution, something that wont irritate eyes

Eyelid anaesthesia

Manually close the eye (and can add atrile saline) to prevent corneal dessication

Clip to remove hair - only if long or dirty, using scissors

Flush repeatedly with sterile saline

Repeat scrub

Adhesive surgical translucid drape can be applied

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Peterson nerve block

A

Causes mydriasis, lack of globe motility, loss of corneal sensation

Insert needle in caudal angle of the supraorbital process and zygomatic arch, manipulate it in front of the coronoid process of the mandible

As withdrawing inject more subcut to give an auriculopalpebral block

Needs corneal care with eye ointment to prevent corneal dessication, abrasion, and ulceration

Risk of respiratory collapse and sudden death

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Four point retrobulbar block

A

Paralysis of extraocular muscles, globe can no longer move, pupil widely dilated, abscence of corneal reflex

Insert needle through conjunctival fornix along the sclera at 10, 2, 4, and 8 o’clock

Complications include retrobulbar haemorrhage, puncture of the globe with the needle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Retrobulbar haemorrhage

A

Complication of retrobulbar injection - not common

Can be sufficient to produce additional pressure on the globe

Surgery should be delayed if this occurs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Puncture of the globe when doing a retrobulbar injection

A

Rare but serious compication

Retrobulbar saline usually reabsorbed with 30-60min

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Respiratory collapse and sudden death after Peterson nerve block

A

Few cases reported

Presumably from accidental anaesthetic injection within the optic nerve meninges or cerebrospinal space

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Indications for enucleation

A

removal of a blind, painful, deformed, or traumatized eye

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Major challenges with enucleation

A

intraoperative haemorrhage and postoperative infection;

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Two approaches for doing an enucleation

A

Transpalpebral

Subconjunctival

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Transpalpebral approach to enucleation

A

Most common approach used in cattle;

Creates a larger soft-tissue defect of the orbit;

Used for cases of severe corneal infections, large corneal, third eyelid, or conjunctival neoplasia;

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Subconjunctival appraoch to enucleation

A

Simpler;

Less time consuming;

Less traumatic;

Less haemorrhage;

Better cosmetic result;

Used for cases of glaucoma, phthisis bulbi, corneal ulcers, corneal neoplasia, irreparable corneal or scleral tears;

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Surgical technique for transpalpebral enucleation

A

Suture the eyelids or clamp together

Circumferential incision around eyelid margin

Transect the lateral and medial canthal ligaments securing the eyelids to the orbit bones

Apply traction in the freed eyelids and continue dissection caudally

Incise the four rectus and two oblique extraocular muscles at the tendon insertion on the sclera

Apply additional anterior and medial traction, minimise traction on the globe to decrease vagal stimulation

Sever the muscle and optic nerve, and any remaining attachments

Carefully palpate to ensure all teh cartilage of the third eyelid was removed

Pack the orit and apply getle pressure as you start closure

Remove all sponges before full closure

Close subcut and skin

Apply pressure bandage over incision for 24hrs

Give antibiotics and analgesics for 5-7 days

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Subconjunctival enucleation surgical technique

A

Eyelid speculum or stay sutures to maintain lids open

Incision on dorsal conjunctiva

Incision of extraocular muscles at their tendons of insertion on the sclera

Isolate the optic stalk and make an incision

Remove the globe

Locate the palpebral conjunctiva and dissect from the inside of the eyelids

Excise the entire thrd eyelid and its conjunctiva

Excise the eyelid margins and control bleeding

Close

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Orbit exenteration

A

Removes the globe as as much of the orbit contents as possible

Preferred surgical approach for extensively invasive squamous cell carcinoma

Starts as transpalpebral approach but dissection is done outside the periorbital connective tissue, follows against the bony orbital wall

All extraocular eye muscles are removed along with a substantial portion of the optic nerve

Drain may be necessary for 48-72hrs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Developmental ocular diseases

A

Micropthalmos

Congenital megaglobus/buphthalmos

Congenital convergent strabismus

Congenital cataract

Dermoids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Aetiology of microphthalmos

A

In utero BVD infection during the middle trimester (125-175 days).

Toxic causes have also been suggested but not proved.

Genetic cause in Guernsey and Holstein, linked to cardiac (VSD) and tail anomalies. Considered recessive inheritance in Guernsey cattle, but unknown in Holsteins.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Clinical signs of microphthalmos

A

Can be unilateral or bilateral

Smaller than normal eye, sometimes only histological evidence of ocular tissue

Corresponding smaller orbits

Chronic conjunctivitis can be present

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Treatment of microphthalmos
Generally no treatment If severe conjunctivitis occurs, with chronic discharge and fly irritation, then enucleation may be necessary to provide comfort to the patient Euthanasia may be indicated
26
Aetiology of congenital megaglobus/buphthalmos
Results from anterior cleavage abnormalities or multiple congenital ocular anomalies producing glaucoma in utero.
27
Clinical signs of congenital megaglobus/bupthalmos
Usually unilateral Noticeably buphthalmic at birth with corneal oedema, central dense opacity, grossly enlarged corneas, and no discernable anterior chamber Grossly enlarged globe may be due to glaucoma, but IOP is normal in some cases
28
Treatment for congenital megaglobus/buphthalmos
Enucleation to ensure patient comfort (eye exposed to damage if not already painful)
29
Congenital convergent strabismus
Autosomal recessive inherited trait in Jersey and Shorthorn cattle. Progressive bilateral convergent strabismus with exophthalmos (BCSE) associated to genes on bovine chromosome 18 in German Brown and Braunvieh cattle.
30
Clinical signs of congenital convergent strabismus
Medial and ventral involuntary deviation of the ocular globe Convergent strabismus can be accompanied or not with exophthalmos BCSE: can result in blindness is degree of rotation is severe
31
Treatment of congenital convergent strabismus
Culling may be indicated if severe vision impairment and animal does not adapt
32
Aetiology of congenital cataracts
May result from an inherited condition or simply an embryological accident during development of the eye. Toxicity or nutritional deficiency (e.g., prolonged maternal hypovitaminosis A, vitamin E/selenium deficiency) BVD infection during the first/mid-trimester of gestation (75-175 days) Exposure to mobile telephone towers and electromagnetic field, or other exposure need to be considered as causes. When affected calves are from common genetic line, heredity should be suspected.
33
Clinical signs of congenital cataracts
Opacity of the lens or its capsule, or both, present at birth; Calf can be blind or have reduced vision; Generally are not progressive cataracts; Calves usually present other abnormalities such as retinal detachment, aniridia, microphakia, and hydrocephalus; Cataracts and microphthalmia with retinal dysplasia (common in BVD exposure in utero);
34
Aetiology of dermoids
Common congenital tumour of developmental origin containing various tissues such as hair follicles, various glandular structures, nerve elements
35
Clinical signs of dermoids
Tumour/skin located on the cornea, conjunctiva, sclera, lacrimal caruncle, or eyelids; Tumour/skin with long hairs; Unilateral or bilateral; Single, multiple, or complex (i.e., involving multiple surface tissues cornea, conjunctiva, third eyelid, lacrimal caruncle, or eyelids); Usually, animals are asymptomatic for a short time after birth if dermoid small or non-haired; Quick development of chronic conjunctivitis, epiphora, blepharospasm and ocular discomfort; Corneal ulceration or scarring may occur (due to poor tear distribution); Visual impairment or blindness in large dermoids; Other intraocular anomalies may be present;
36
Treatment of dermoids
Surgical excision (keratectomy if on the cornea) Topical antibiotic 1% Atropine (3-4x a day for 7-10d)
37
Bacterial ocular diseases
Orbital cellulitis Infectious bovine keratoconjunctivitis Bovine irititis
38
Aetiology of orbital cellulitis
Invasion of the orbital soft tissue by opportunistic bacteria after punture wounds and lacerations of the periocular area, eyelids, or conjunctiva Can also occur after severe ocular infections that progress from endopthalmitis to panopthalmitis
39
Clinical signs of acute orbital cellulitis
Rapid onset of warm and painful swelling of the orbit, eyelid, and third eyelid Chemosis of the conjunctiva Mild to severe exophthalmos Variably prolapse of the third eyelid (more severe if abscess in the medial region of the orbit) Keratitis with corneal ulceration Fever Anorexia
40
Clinical signs of chronic orbital cellulitis or abscessation
Painful exophthalmos with soft tissue swelling, usually more localised Fever is inconsistent
41
Diagnosis of orbital cellulitis
Clinical signs Orbital ultrasonography and radiography
42
Treatment of acute orbital cellulitis
Systemic broad-spectrum antibiotics NSAIDs Warm compresses or gentle hosing with warm water Eyelid massage and eyelid manipulation with gentle globe retropulsion Topical antibiotic or petrolatum lubricant applie to the cornea +/- 1% atropine if corneal ulceration Temporary tarsorraphy considered if exophthalmos does not improve within 24hrs If exposure keratitis results in corneal ulceration and rupture then enucleation may be required Any abscesses should be opened and drained (penrose drain) with gentle flush 1-2x a day
43
Prognosis of acute orbital cellulitis
Good for acute orbital cellulitis (most cases resolve in 5-7 days) but antibiotic should not be stopped before 14d as will usually recur
44
Infectious bovine keratoconjunctivitis
Also known as 'pink eye', blight, and 'new forest disease' Most common eye disease in cattle Affects all ages but young cattle more susceptible Commonly unilateral Highly contagious Higher incidence in Herefords and Hereford crosses Welfare and economic impacts
45
Aetiology of infectious bovine keratoconjunctivitis (New forest eye)
Moraxella bovis Haemolytis gram-negative coccobacillus and can express hydrolytic enzymes such as pillin and cytotoxin Source of the bacteria is commonly asymptomatic carrier cattle Transmission occurs by mediate contagion and by flies
46
Risk factors for infectious bovine keratoconjunctivitis
IBR virus, Moraxella bovaculi, and Mycoplasma spp. have also been associated to IBK - Enhance the risk for IBK by increasing the ocular and nasal discharge, allowing the spread of Moraxella bovis FLies Solar irradiation Mechanical trauma or irritation to the cornea
47
Diagnosis of infectious bovine keratoconjunctivitis
Clinical signs and herd morbidity often are enough for IBK diagnosis Fluoroscein test Culture
48
Clinical signs of infectious bovine keratoconjunctivitis
Initially: - conjunctivitis (redness, serous to mucopurulent ocular discharge, blepharospasm, lacrimation, photophobia, corneal oedema and corneal ulceration) Progression: - Corneal ulcers become less circular with meting edges of necrotic aspect - centre may become darker as Descemets membrane is approached - corneal oedema intensifies - severe pain and loss of appetite and bodyweight - infected eyes can appear blue (oedema), red (vessels, granulation tissue), and yellow (necrosis, stromal abscesses)
49
Corneal ulcers healing
Superficial ulcers epithelialize Deep ulcers will first have the crater filled with granulation tissue and then epitheliazation, changing the central colour from pink to white Corneal oedema resolves from periphery towards central lesion Corneal deep straight vessels recede Complete corneal healing takes weeks to months
50
Recovered eyes that have been treated for infectious bovine keratoconjunctitivitis
Common central nebulas, maculas, or leukomas (i.e. white scar), and little visual loss
51
Untreated eyes with severe infectious bovine keratoconjunctavitis
Can develop descemetoceles, corneal perforation, or keratoconus with endophthalmitis, or panophthalmitis
52
Severe IBK
Can also lead to residual posterior synechiae and cataract formation
53
Treatment of infectious bovine keratoconjunctivitis
May have spontaneous recovery in mild cases Topical, subconjunctaival, or parenteral administration of antibiotics E.g. penicillin G, oxytetracycline, florfenicol, tulathromycin Additional therapy: atropine, NSAIDs Confine the animal to avoid sunlight, use temporary adhesive eye patches to provide relief from bright light
54
Prevention of infectious bovine keratoconjunctivitis
Quarantine purchased cattle and management if new stock separately Reduce flies Reduce mechanical trauma - cut mature grass before turnout Optimise immune response - nutrition, vaccination Use disposable gloves between animals, change or disinfect protective clothes, halters, and instruments
55
Bovine irititis
'silage eye', listerial keratoconjunctivitis and uveitis Unilateral or biateral keratouveitis
56
Aetiology of bovine irititis
Listeria monocytogenes Commonly occurs in stressed cattle, or poorly managed and fed cattle Found in improperly stored silage - if oxygen available the listeria can survive lower pH
57
Risk factors for bovine irititis
Late autumn, winter, and early spring when the animals are housed, and silage is fed; Feeding big bale silage in ring feeders Feeding ad libitum silage from clamp during the outdoor period; Feeding improperly made silage (e.g., contaminated with soil) and/or badly managed (e.g., perforation of bale silage wrapper); Presence of other cattle with clinical listeriosis; Increased susceptibility of individual animals: § Poor nutritional status; § Sudden changes to very cold and wet weather; § Stress of late pregnancy and parturition; § Overcrowding and unsanitary conditions with poor access to feed supplies and poor herd management;
58
Diagnosis of bovine irititis
Clinical signs Bacterial culture or PCR testing
59
Clinical signs of bovine irititis
Initial signs: mild epiphora and catarrhal conjunctivitis, photophobia, blepharospasms Non-ulcerative keratitis with marked blinding corneal oedema (Acute oedema that starts peripherally and progressed toward the centre very quickly), intrastromal abscess formation and other severe corneal changes, with or without hypopyon or other signs of uveitis
60
Treatment of bovine irititis
Course of disease can take 2 weeks with or without treatment Antibiotics like penicillin, oxytetracycline, ampicillin, and erythromycin have been reported efficacious topically or parenterally Cloxacillin eye ointment can also be used Topical atropine to improve animal comfort and reduce uveitis sequelae Topical dexamethasone may improve signs of uveitis
61
Prevention of bovine irititis
Hygiene and cleanliness Appropriate preparation and storage of silage Minimising eye contact with food through feeding methods Improve nutritional status of the animal Improve housing conditions
62
Ocular neoplasia
Ocular squamous cell carcinoma
63
Ocular squamous cell carcinoma
AKA cancer eye Primary neoplasm of epithelial origin Malignant tumour Particularly cmomon in cattle with unpigmentated skin on the face
64
Aetiology of ocular squamous cell carcinoma
Poorly understood Breed susceptibility, lack of circumocular and corneoscleral pigmentation, exposure to UV light, viral infection, more common in cattle >5yo, nutrition
65
Diagnosis of ocular squamous cell carcinoma
Clinical signs Cytology and histopathology
66
Clinical signs of ocular squamous cell carcinoma
Stage 1: plaques (small, raised, grey-white areas in the affected tissue) Stage 2: keratoma or keratoconthomas (more frequent on the lower eyelid; skin growths coated with eye secretions and debris) Stage 3: papillomas (wartlike proliferative appearance) Stage 4: carcinomas (more irregular and nodular and may be pink from an increased vascular supply; can have necrotic and ulcerated areas) Ocular discharge may be present due to mechanical irritation Painless until advanced Otherwise the animals are healthy
67
Treatment of ocular squamous cell carcinomas
Small precursor lesions may regress without treatment Treatment of small lesions is usually effective and curative Excision of the lesions with 2-3mm margin and cryosurgery or radiofrequency hyperthermia Larger lesions/tumours may require more radical surgery techniques like enucleation Radiation unlikely in food producing animal Can metastasize but likelihood inreases with duration
68
Prevention of ocular squamous cell carcinoma
Breeding program to increase degree of periocular pigmentation in white faced beef cattle Remove genetically susceptible cattle from the breeding herd Decrease exposure to UV light
69
Ocular injury
Toxic injury Corneal foreign body trauma
70
Aetiology of ocular toxic injury
Most commonly caused from accidental exposure of the cornea to exogenous chemicals E.g. chlorhexidine, insecticides, other chemicals, including organophosphate fly repellents, anhydrous ammonia, chloride bleach
71
Clinical signs of ocular toxic injury
Acute, widespread, corneal epithelial loss and ulceration Severe, permanent corneal opacity due to epithelial necrosis and stromal injury
72
Aetiology of corneal foreign body trauma
Usually foodstuffs, could be plant material, hairs, metallic, glass, or others Commonly happens after windstorms or tail switching
73
Clinical signs of ocular foreign bodies
Squinting, tearing, photophobia Mucopurulent ocular discharge Rubbing the affected eye, blink frequently and forcefully, frequent extrusions of the third eyelid Painful eye
74
Treatment of ocular foreign body
Removal eith local or GA should be sent fot C&S Topical treatment with antibiotics and topical atropine Surgery may be necessary to repair defects
75
Causes of blindness with PLR present in both eyes
Polioencephallomalacia (excess of sulphur or thiamine deficiency) Lead or other heavy metal toxicity Sodium ion or salt toxicity, or water deprivation Hepatic encephalopathy Ketosis Hypoglycaemia TEME or Histophilus somni - related vasculitis, thrombosis, haemorrhage, or other lesions in the cerebral cortex Other causes of cerebrocortical disease Some rabies cases
76
Causes of blindness where PLR is absent in both eyes
Vitamin A deficiency Locoweed toxicity Male fern toxicity Mouldy corn TEME or histophilus somni related vasculitits, thrombosis, retinal haemorrhage, or other lesions in the retinas, optic nerve, optic chiasm, proximal optic tracts Other toxins or chemicals
77
Diseases that can cause conjunctivitis
BVD Malignant catarrhal fever IBR Bluetongue Besnoitiosis Rinderpest
78
Diseases that can cause uveitis
Septicaemia Malignant catarrhal fever Listeriosis (anterior) TEME (posterior) Mycobacterium bovis
79
Diseases that cause keratitis/keratoconjunctivitis
BVD Listeriosis Malignant catarrhal fever IBR Chlamydia Mycoplasma spp.
80
Causes of central blindness
Hepatoencephalopathy Hypomagnesaemia Hypovitaminosis A Severe ketosis Lead toxicity Listeriosis Malignant catarrhal fever Plant toxicity Polioencephalomalacia Salt poisoning Prussic acid toxicity Rabies Ruminal acidosis Sporadic bovine encephalomyelitis Thromboembolic meningoencephalitis Urea poisoning

Cattle II (11 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions