Equine ophthalmology Flashcards
1
Q
Adaptations of the horse eye
A
- Large horizontal eye and cornea increase the amount of light able to rech the retina
2
Q
Visual acuity of the horse in relation to the dog and cat
A
- Approaches 20/20 and exceeds the dog and cat
3
Q
Are horses better at peripheral vision or binocular vision?
A
Peripheral vision
Up to 350 degrees
4
Q
Blind spots for the horse
A
- Forehead, below the nose, and directly behind the horse like the width of the head
5
Q
Characteristics of horse fundus
A
- Large tapetum fibrosum (paurangiotic)
- No retinal arteries or veins
- Only capillaries the periphery of the optic nerve head
6
Q
What color is the horse lens?
A
- Yellow
7
Q
Role of the yellow horse lens
A
- Improves visual acuity
- Decreases glare
- More prominent with age
8
Q
What shape is the horse pupil?
A
- HOrizontal
- Can dilate and become circular
9
Q
Function of corpora nigra (iridica)
A
- Shade from the posterior of the iris epithelium coming forward
10
Q
Ability of horse to constrict and dilate pupil
A
- Can dilate 3-6x more than dogs and humans
- Ability of the pupil to constrict to form 2 pupils; thought to improve visual acuity
11
Q
What’s the problem with corpora nigra cysts?
A
- Cause visual impairment, especially when the pupil is constricted
12
Q
Treatment for corpora nigra cysts
A
- Diode laser to destroy cyst or manual destruction (referral)
13
Q
What causes pathology to the corpora nigra most commonly?
A
- Chronic uveitis
- Posterior synechia or atrophy indicates chronic inflammation from ERU
14
Q
Reflex uveitis in horses
A
- Often occurs secondary to pain
15
Q
How does a collapsed iridocorneal angle look in the horse?
A
- Bright white line
16
Q
What can cause visual impairment in the horse?
A
- Iris cysts
- Cataracts
- Vitreal opacities
17
Q
Is asteroid hyalosis in horses normal?
A
- No
18
Q
Who gets congenital stationary night blindness?
A
- Appaloosa horses with leopard gene (LpLp)
19
Q
Appearance of retina in horses with congenital stationary night blindness?
A
- Normal
- ERG will be abnormal
20
Q
What is the primary issue with congenital stationary night blindness?
A
- ERG abnormal
- Neural transmission defect in retina
21
Q
Lp gene
A
- Dominant and associated with coat color (few spot, leopard, etc.)
- Commonly have striped hooves, white sclera, and mottled skin around mouth, eyelids, anus, and genitalia
22
Q
Multiple ocular abnormalities - who gets?
A
- Rocky Mountain Horse
- Kentucky Saddle Horse
- Mountain Pleasure Horse
- Associated with silver dapple gene
- Chocolate coat with white mane and tail most affected
23
Q
Congenital ocular disorders in horses
A
- Microphthalmia
- Cataracts
24
Q
Naso-lacrimal duct atresia
A
- Tears go down the face
25
Scrolled cartilage
- Flipped over TEL cartilage
26
Diagnosis of naso-lacrimal duct atresia
- N-L flush required to make diagnosis
| - If it doesn't flush, there's atresia
27
Entropion in horses - risk factors?
- Foals with neonatal maladjustment syndrome, corneal ulcers, and secondary to microphthalmia
- Hereditary in TB and QHs
- Results from cachexia, scarring, pthisis bulbi
28
Pthisis bulbi
- SO much damage that the eye stops producing aqueous and huts down
29
Normal foal eyes at birth
- Open and visual
- Slight ventromedial strabismus
- Prominent Y-sutures in lens
- Have round pupils for about 2 weeks
30
Episcleral or subconjunctival hemorrhage in foals
- Due to trauma in delivery
| - Should clear in about a week or a little over
31
Neonatal septicemia - which organs does bacteremia spread to?
- Joints, lungs, umbilicus, and eye
32
Mechanism of uveitis with neonatal septicemia
- Intraocular inflammation --> increased vascular permeability --> proteins and cells passing into the aqueous
33
Appearance of the eye in a foal with neonatal septicemia and subsequent uveitis
- Green hue to the iris from fibrin initially; progresses to miosis, hyperemia, flare, hypotony, hyphema
34
How to examine a horse for symmetry?
- Stand several feet away from and at the front of the horse
- Assess facial orbital and eyelid position
- Pupil size and position
- Assess direct and consensual PLR (not as strong as dogs and cats)
- Elicit blink reflex (eyelids should close completely
35
Facial nerve paralysis appearance
- Muzzle droops towards the unaffected side
| - Ear and eye droop
36
Causes of facial nerve paralysis
- EPM
- Trauma
- Encephalitis
- Aspergillus
- Temporohyoid osteoarthropathy (THO)
37
Sequelae of facial nerve paralysis
- Exposure keratitis and corneal ulceration
38
Treatment for facial nerve paralysis
- Have to place a sub-palpebral lavage system to keep the cornea hydrated
- Topical abx for corneal ulcers
- Lubricants
- Temporary partial tarsorrhaphy
39
PNS and facial nerve paralysis
- Possible decreased tear production
40
Prognosis for facial nerve paralysis
- Ultimately the horse should learn to retract the globe and spread tear film with the third eyelid
41
Which nerve do we block for motor with eye exams?
- Auriculopalpebral, a branch of the facial nerve
42
Where is the auriculopalpebral nerve located for a block?
- Zygomatic arch
43
Function of the facial nerve in relation to the eye
- Closes the eye
44
Which nerve is the sensory supply to the eye?
- Trigeminal nerve
| - Frontal nerve is what we technically block to block sensation
45
Where do we block for sensory?
- Supraorbital foramen to get the frontal nerve out of the trigeminal nerve
46
What does the frontal nerve block sensory to?
- Upper eyelid
| - If you want to do medial or lateral canthus, that nerve block will not cover it
47
How to block the frontal nerve?
- Place 25 ga needle into supraorbital foramen and inject 1-2 mL lidocaine
48
How to block auriculopalpebral nerve?
- Palpate nerve over the zygomatic arch, and inject SQ over the nerve
- May need IV sedation or a twitch first or in addition
49
What are the more common equine eyelid abnormalities?
- Lacerations**
- blunt trauma
-
50
Other causes of equine eyelid abnormalities that are less common
- Entropion (not common)
- Distichiasis (uncommon but may lead to delayed corneal ulcer healing)
- Meibomian gland adenitis/eosinophilic granuloma
- Parasitic disease with habronema, onchocerca, thelazia
- Neoplasia with actinic dermatitis, SCC, sarcoid, melanoma
51
How well do eyelid lacerations heal in the horse?
- Quite well due to vascular supply
52
Treatment of eyelid lacerations in horses
- Minimal debridement to save the lid margin
- Precise lid margin apposition
- 2 layer closure, no suture against the cornea (Figure of 8)
53
How to close an eyelid laceration on a horse?
- 2-layer closure
- Conjunctiva and skin
- Close lid margin first
- Use 6-0 vicryl SQ (DO NOT let sutures contact cornea or penetrate conjunctiva)
- 6-0 or 5-0 silk for skin
- Rule out corneal intraocular and orbital lesions
54
What is the issue if an eyelid laceration is either not repaired or poorly repaired?
- Leaves notch defect and uneven pressure on the cornea
55
Orbital fracture treatment
- If small and non-displaced, the fractures can be left to heal if they do not impose on the eye
- Be sure the eye is not ruptured
56
Treatment for a ruptured eye?
- Emergency enucleation
57
Eosinophilic granuloma sequela
- Exposure keratitis
| - Eyelid does not contact cornea resulting in corneal ulceration/stromal abscess
58
Treatment of eosinophilic granuloma
- Dermatologic condition (blepharitis) treated with local and systemic steroids, antibiotics, and/or anti-fungals based on cytology/culture/histopath
- May require aggressive intra-lesional injection with dexamethasone UNLESS there is an ulcer
59
Eosinophilic granulomas - what are they?
- Meibomian glands can get granulomas (parasitic; Habronema)
60
Eosinophilic granuloma prognosis
- If soft, they may go down; once hard they're almost impossible to fix
61
Treatment of SCC
- Surgical excision, cryotherapy, radiation, photodynamic therapy, intralesional chemo
- EARLY aggressive treatment for best results
- Clean margins
62
Behavior of SCC in horse eyes
- Most will recur
- Locally invasive
- Later metastatic
63
Who gets SCC (horses)?
- Light skinned horses
64
How do normal horse TELs look?
- Curly
| - Should be smooth and healthy conjunctival tissue
65
What are the two most common sites of SCC in horses>
- Third eyelid
| - Lateral limbus
66
What will give you the best prognosis for conjunctival and TEL SCC?
- Early excision with clean margins for best prognosis
| - Other treatment options include cryotherapy and photodynamic therapy
67
Appearance of conjunctival or TEL SCC
- COuld be petechiation and rough looking
68
TEL Adenocarcinoma how to diagnose?
- Biopsy (must cut out the third eyelid)
| - MRI for margins
69
Treatment for TEL Adenocarcinoma in horses
- Agressive surgical excision
| - Radiation therapy
70
Where is the bulbar conjunctiva normally pigmented in horses? What can happen if it's not pigmented?
- Usually pigmented medially and laterally in the horse
| - Lack of conjunctival pigment over lateral sclera orTEL predisposes to SCC
71
How do we identify cause of conjunctivitis?
- Exam and elimination
- ook for trauma, foreign body, or parasite
- Look for corneal ulcer or intraocular disorder
- Then look at systemic disease (fever, LN, anorexia)
- Cytology
- Culture
- Biopsy
72
Appearance of conjunctivitis in horses
- Hyperemia, chemosis, discharge serous to mucopurulent, blepharospasm
73
Do clinical signs of conjunctivitis change based on the etiology?
- NO
74
Causes of conjunctivitis in horses
- Trauma
- Ulcer
- Bacterial infection
- Fungal infection
- Parasitic infection
- Eosinophilic inflammation
- Uveitis
- Non-ulcerative keratitis
- Glaucoma
- Neoplasia
- Etc.
75
Distal L-N catheter placement for flushing in horses vs mules
- Infero-medial location in the horse where the pigmented and non-pigmented areas meet
- In the mule the distal puncta is located superior-lateral nasal fold
76
Treatment of conjunctivitis in horses
- Treat primary disease (ulcer, foreign body, parasites, neoplasia, etc.)
- Environmental irritants/allergies often respond to BNP ointment
- Rule out intraocular and systemic disease
- May need BNP-HC if no ulcer
- Careful with dexamethasone
77
What to do about depigmentation over the temporal or lateral bulbar conjunctiva?
- Biopsy it with excisional biopsy
| - Cytology and histopathology
78
Habronema - how does it occur?
- Larvae deposited on wounds near the eye by flies
79
Diagnosis of Habronema
appearance or biopsy
80
Appearance of Habronema
- Gritty necrotic debris
81
Biopsy of Habronema
- Granulomatous reaction with eosinophils and mast cells
82
Treatment for Habronema
- Ivermectin
| - Topical and sytemic-anti-inflammatory drugs
83
Prevention of Habronema
- Control fly population
| - Use fly masks
84
What can ocular onchocerciasis cause?
- Lateral conjunctival vitiligo (depigmented)
- Keratitis
- Keratoconjunctivitis
- Anterior uveitis
- Posterior uveitis
- Peripapillary chorioretinitis
- Really should always be on the dfdx list
85
Diagnosis of ocular onchocerciasis
- Diagnose (eyelid, cornea, conjunctiva) with biopsy
86
Treatment of ocular onchocerciasis
- Systemic ivermectin or moxidectin
- Systemic NSAID
- Topical steroids
- Need to control ocular inflammation with infection and as parasite dies
87
In general should you use steroids in horses?
- No
| - Can cause ulcers
88
Causes of ulcerative keratitis in horses
- Usually traumatic
- Sharp or blunt or both
- May be viral (herpes)
- EHV2, EHV5
89
What are ulcer categories in horses?
- Uncomplicated
- Indolent
- Infected
- Melting
90
Uncomplicated ulcers
- Superficial, not infected
91
How quickly should uncomplicated ulcers heal?
- 3-5 days
92
Indolent ulcers
- Non-healing ulcer with loose epithelium, older horse
93
Infected ulcers
- Bacterial, fungal
94
Melting ulcers characteristics
- can be infected or sterile
95
Treatment for loose epithelium on an ulcer in horses depending on if they are young or older-
- If younger, look for FB, distichia, infection
| - If older, needs debridement
96
Clinical signs of ulcerative keratitis
- Pain due to corneal pain and reflex uveitis
- Blepharospasm
- Photophobia
- Epiphora
- Miosis
- Discharge - serous to mucopurulent
- Fluorescein stain uptake
97
What causes the pain with ulcerative keratitis?
- Corneal pain and reflex uveitis
98
Cause of uncomplicated superficial corneal ulcers
- Mostly traumatic
99
How to treat uncomplicated superficial corneal ulcers?
- Broad spectrum abx (neomycin/polymixin/bacitracin)
| - Atropine, Systemic NSAID like flunixin, and pain management (preventing reflex uveitis)
100
How does atropine prevent reflex uveitis?
- Mydriatic and cycloplegic
101
What pain management for horses with superficial corneal ulcers that are uncomplicated?
- Topical morphine
102
What should a circular ulcer make you think in a horse?
- Foreign body
- Look for underlying cause
- Especially if it's deep or infected by non-healing
103
Indolent ulcer appearance
- Loose epithelium
104
Stromal injury in horses healing time
- Longer healing time than superficial ulcers
105
When do blood vessels enter the cornea?
- After 1 week
| - Advance 1 mm/day until cornea has healed
106
Treatment for stromal injury
- Continue antibiotics, atropine
| - Banamine +/- diclofenac until no stain uptake
107
Equine herpes keratitis signs
- Painful
- Punctate or dendritic ulcers
- Can be ulcerative or non-ulcerative
108
Diagnosis of Equine Herpes keratitis
- Careful examination to rule out traumatic injury such as dirt and debris
- Clinical signs or PCR
109
Which strains of EHV cause keratitis?
EHV 2 and 5
110
Treatment for equine herpes keratitis
- Oral lysine and topical trifluridine
111
How might you differentiate ocular disease vs another disease from two horses that look quite similar with funky eyes?
- if the eye is slammed shut, that could indicate pain
| - In an abscess, there might be copious ocular discharge but the eye itself might not hurt
112
For a terrible looking eye with copious ocular discharge and severe blepharospasm, what are your differentials?
How might you differentiate?
- Fungal, bacterial, or eosinophilic
| - Differentiate with cytology
113
Eosinophilic keratitis treatment (with bacteria and stromal abscesses)
- Keratectomy probably
- Topical mast cell blockers
- Cyclosporine
- Systemic cetirizine
114
What should you do with any complicated ulcers?
- Cytology
- Culture
- Sensitivity
115
Bacteria present with secondary infections on equine corneal ulcers?
- Staph
- Pseudomonas
- Strep
116
Fungi that can be present as secondary invaders for equine corneal ulcers
- Aspergillus, Fusarium, Penicillium, Alternaria
117
What is the most virulent bacteria with bacterial keratitis?
- Pseudomonas aeruginosa
| - Produce endotoxins, exotoxins, proteases
118
Beta-hemolytic strep and bacterial keratitis
- Produces exotoxins, can digest conjunctival and amnionic graft and sutures
- Strep eat everything
- Compound IV penicillin, chloramphenicol, ofloxacin
119
Treatment of bacterial keratitis
- C&S (start treatment pending results based on cytology)
- SPL (Sub-palpebral lavage
- Chloramphenicol
- Gentocin
- Atropine
- Flunixin
- Doxycycline orally
- Topical NSAID
120
When is surgery indicated for treatment of bacterial keratitis?
- if not responsive to medical treatment or if there's an abscess or melting cornea
- She will cut the badness out and put a graft over it
121
Appearance of fungal keratitis
- Minor abrasions to deep ulcers or stromal abscesses
- Fluffy to plaque-like
- Gray, yellow, brown
- Punctate rose bengal positive (similar to herpes)
- Often a history of extensive treatment with antibiotics or steroids
122
Diagnosis of fungal keratitis
- Culture and cytology
- PCR
- Histopathology
123
Treatment for fungal keratitis
- Topical antifungals (natamycin, clotrimazole, silver sulfasalazine)
- Serum
- EDTA
- Doxycycline
- Atropine
- Antibiotics
- Oral fluconazole
- IV or oral flunixin
- Surgery
124
When to consider fungal keratitis?
- All non-healing or relapsing corneal ulcers in horses, or horses treated with steroids and multiple antibiotics
125
Prognosis of fungal keratitis
- Ulcers can melt rapidly
| - Guarded if stromal abscess or rupture
126
What is the only effective treatment in general for melting fungal keratitis?
- Enucleation
127
Treatment for melting ulcers (that maybe aren't as severe)
- Serum Q2 alternating with EDTA q2hr
- Topical antibiotic (chloramphenicol, BNP, gentocin)
- Anti-fungal if indicated
- Atropine
- Systemic NSAID
- N-acetylcysteine 10%
All topical meds should be separated by at least 15 minutes; SPL rinsed between meds
- Doxycycline (topical and oral)
128
Stromal abscess appearance
- Solid creamy white or yellow stromal opacity
| - Painful
129
Possible etiologies of stromal abscess
- Bacterial
- Fungal
- Sterile
130
Treatment for stromal abscess
- Need antibiotic (chloro, ofloxacin) or antifungal (voriconazole) that penetrates cornea
- Best option is surgical excision with graft
131
Endothelial ulcer prognosis?
- guarded prognosis
132
Clinical signs of equine acute uveitis dependent on cause
- They are the SAME regardless of the cause
- Trauma
- Corneal ulcer
- Stromal abscess
- Etc.
133
Systemic infectious diseases with ocular signs
- Equine infectious anemia
- Rabies
- Adenovirus
- Influenza
- West Nile Virus
- Strangles
- Encephalitis
- Apsergillus
- Strep Equi
- EHV
- EVA
- Brucellosis
134
Clinical signs of Acute uveitis (and one of the most important ones first)
- Miosis****
- Blepharospasm
- Conjunctival hyperemia
- Periocular swelling
- Lacrimation
- Corneal edema
- Flare
- Hypopyon
- Corneal vascularization
- Low IOP (hypotony)
135
Definition of Equine Recurrent Uveitis
- Any case that presents with uveitis WITHOUT evidence of underlying disease and the horse has had previous episodes of uveitis
136
Leading cause of blindness in horses
- ERU
137
What is thought to be an inciting cause of ERU in horses?
- Leptospirosis
138
Who gets ERU?
- ANY age, breed, or sex
| - Appaloosas, Fresians, Warmbloods
139
What are the three types of ERU?
1. Insidious
2. Classic
3. Posterior segment
140
Insidious ERU
- Low grade inflammation (not usually seen clinically) and leads to gradual/cumulative destruction
141
Classic ERU
- Most common
- Episodes of active inflammation followed by "quiet" periods
- Squinting, painful, tearing
142
Posterior segment ERU
- Inflammation in vitreous and retina
- More common in Warmbloods and drafts
- I guess they see it in Europe more
143
Who is at highest risk of ERU?
- Appaloosas
- Higher incidence of blindness with ERU
- Higher % associated with Leptospirosis
- 88% are bilaterally affected
144
Warmbloods and ERU
- More prone to posterior segment but can get any form of the disease
- German and Dutch Warmbloods may have a genetic correlation
145
Leptospirosis and ERU
- Leptospira interrogans
- Lepto antibodies have been found in serum, aqueous humor, and vitreous in affected horses
- Interaction between Lepto and equine immune system
146
Vaccination for Lepto as prevention
- NOT PROVEN
| - Currently not recommended
147
Treatment of Uveitis
- Atropine to effect (monitor for colic; check IOP)
- NPDex if NO ULCER
- Topical NSAID to facilitate pupil dilation
- Flunixin (Banamine is gold standard)
- +/- Ciprofloxacin
- +/- Doxycycline
- Sub-palpebral lavage
- Treat EARLY AND BE AGGRESSIVE IN TREATMENT
148
Cyclosporine implants
- EARLY referral is critical
| - Referral procedure
149
Who should be referred for cyclosporine implants?
- Horses with episodes of uveitis that are responsive to topical anti-inflammatories
150
Where does the cyclosporine implant live?
- Between sclera and uvea/choroid
| - Absorbed in the choroid
151
Signs of previous uveitis
- Iris depigmentation and atrophy
- Pigment on anterior lens capsule
- Corpora nigra atrophy
152
Chronic ERU signs
- Cataracts (can be small)
- Glaucoma
- Blindness
- Butterfly lesions
- Stria (signs of glaucoma)
153
Chorioretinal scarring appearance on fundic exam
- Bullet hole lesions (can be incidental)
| - Scarring
154
Sequelae of chronic uveitis
- Glaucoma and lens luxation or pthisical eye
155
What form of uveitis do Appaloosas get?
- Insidious or non-painful form of uveitis
| - Appaloosas and Fresians often present with end-stage disease
156
How does glaucoma happen?
- Sink analogy
- Tap: ciliary body, never over-produces fluid
- Drain: iridocorneal angle and uveoscleral outflow (important in the horse)
- Chronic inflammation creates cellular debris and PIFMs with fibrin --> clogs the drain --> fluid cannot get out --> increased pressures
157
Appearance of glaucoma in horses
- Corneal edema with glaucoma or eye may appear normal with high IOP until buphthalmic
- Diffuse severe edema
158
Striae
Descemet's membrane break
159
What are striae pathognomonic for?
- previous IOP elevation
160
Treatment of glaucoma
- Dorzolamide/timolol for life
| - Horses do NOT respond to latanoprost
161
If visual, glaucoma treatment?
- Referral for surgery
| - Buying them time
162
If blind, glaucoma treatment?
- Enucleation
163
Glaucoma surgery?
- Laser surgery
- Transccleral cyclophotocoagulation (kills the ciliary body)
- Micropulse
- Ahmed valves
164
Heterochromic iridocyclitis/keratitis
- newly described form of uveitis
165
Appearance of heterochromic iridocyclitis/keratitis
- Corneal edema
- Endothelial pigmentation
- Mild inflammation
- Painful
166
How does heterochromic/iridocyclitis/keratitis respond to medication?
Poorly
167
Who gets HIK?
Warmbloods
168
Cow retrobulbar disease
- Orbital cellulitis
- Frontal sinusitis
- LSA
169
Causes of orbital cellulitis
- Trauma
- Punctures
- FB
- Actinobacillus
- Clostridium
- Panopthalmitis
170
Frontal sinusitis causes
- Dehorning related in 67% of cases (Actinomyces pyogenes)
| - Respiratory tract disease (Pasteurella multocida)
171
Lymphosarcoma cause
- Bovine Leukemia virus
172
BLV transmission
- Horizontal (vaccines, dehorning, castration, ear tags) or vertical (in utero)
173
How long are cattle infected with BLV?
- Permanently
| - Permanent carriers
174
What % of cows infected with BLV will seroconvert?
- 30%
| - Lymphocytosis months to years after infection
175
Appearance of lymphoma with bovine orbital neoplasia
- Exophthalmos
176
Economic impact of bovine ocular SCC
- Ocular squamous cell carcinoma has serious economic impact
- 4th leading cause of carcass condemnation post-mortem
177
Signalment of bovine OSCC
- Older cattle (~8 years)
- Herefords are over-represented as well as Ayrshires (dairy)
- Black baldies
178
Risk factors for bovine OSCC
- Increased risks at higher altitude
- Higher UUV light
- Depigmented eyelids
179
What % of cattle are affected bilaterally?
- 35% of cattle are affected
180
Clinical signs of bovine OSCC
- Lesions on bulbar conjunctiva or cornea that starts as a plaque
- Carcinoma in situ arises directly from a plaque (grossly like a papilloma) --> progress and invade
181
Metastatic potential of bovine OSCC
- It exists
- Most commonly to LN or intracranial, can extend hematogenously to multiple organs
- Animals with invasive OSCC have a higher level of metastasis
182
Diagnosis of bovine OSCC
- Cytology +/- histopath
183
Treatment of bovine OSCC
- need a biopsy
- Not all precancerous lesions progress
- About 1/3 cspontaneously regress
- Salvage procedures (extenteration)
- Cryotherapy (Success with small lesions)***
- Immunotherapy
184
Extenteration
- Taking out the eye plus everything around them
185
Bovine orbital neoplasia and transpalpebral exenteration
- Because SCC invades the retrobulbar space
- 81% of cows were exenterated due to SCC
- Holsteins over-represented with lymphoma
- Recurrence is fairly common
186
Infectious bovine keratoconjunctivitis losses
- World-wide distribution
- Economic losses are HUGE ($150+ million in US)
- Decreased weight gain and milk production
187
What causes IBK?
- Moraxella bovis
188
What is Moraxella bovis?
- Gram negative bacillus
189
What other pathogens contribute to severity of IBK?
- IBR, Mycoplasma, Thelazia, Listeria
190
***What form of M. bovis causes IBK acute disease?
- Piliated, hemolytic form of M. bovis***
191
What form of M. bovis causes IBK carrier disease?
- Nonpiliated, nonhemolytic forms
192
Risk factors for IBK
- herefords and Murray Grays
- Age (younger <2 years)
- UV radiation
- Comorbidities
- Face flies
- Bovine tears lack lysozyme
- Herds vaccinated for IBR
193
What enzyme do bovine tears lack?
- Lysozyme
194
How does herd vaccination act as a risk factor for IBK?***
- Modified live and shipping can lead to outbreaks of pink-eye***
195
Transmission of IBK
- Us!
- Sources
- Direct contact, handles, fomites, and mechanical vectors (flies)
196
Source of IBK
- New animal or carrier in the herd
| - Non-pathogenic strain reverts to pathogenic strain over winter and the ninfects calves
197
Clinical signs of IBK
- Day 1 pain --> ulcer that progresses rapidly --> may perforate by day 5-6
- By weeks 2-3 the eye has perforated and begun to heal
- By 1-2 months only a faint scar may remain
198
Treatment of IBK difficulties
- Self limiting, so epople don't want to treat a bunch
| - No one treatment is effective always
199
Resistance to IBK treatment
- Tylosin, lincomycin, erythromycin
200
Selection of therapy for IBK: what to consider in dairy vs beef?
- Dairy: milk withdrawal times
| - Beef: Infrequent handling +/- respiratory disease
201
Treatment for IBK
- Topical isn't realistic
- Bulbar subconjunctival
- Parenteral antibiotics
- Surgery?
- ALWAYS CHECK FDA REGS of antibiotics for food animal
202
Bulbar subconjunctival antibiotics for IBK
- PPG lasts ~40 hours
| - Oxytet can have severe reactions - don't do
203
Parenteral antibiotics for IBK
- SQ PPG lasts about 67 hours
| - Oxytet may cause necrosis at injection site
204
Vaccination for IBK
- Controversal - incomplete protection
| - True effective vaccine may be available later
205
Current IBK vax recommendations in severely affected herds***
- Culture and swab
- Vaccinate 6 weeks before onset of disease season and 3 weeks before fly season
- Calves should be vaccinated at 21-30 days of age and booster 3 weeks later
- Adults receive 2 initial vaccines then yaearly boosters
- DO NOT GIVE IBR (MLV) and then stress cattle
206
Malignant catarrhal fever - is it reportable?
- YES
207
Agent of malignant catarrhal fever?
- OHV2
208
Signs of malignant catarrhal fever
- Corneal edema, corneal ulcers, uveitis
- Non-improvement of corneal edema is associated with poorer prognosis
- You can't tell prognosis based on initial appearance
209
Vitamin A deficiency in cows -
- Can cause blindness
| - optic nerve atrophy and retinal degeneration
210
Entropion in sheep and goats - how often?
- Quite common
211
Entropion in sheep and goats breeding recs
- Do not keep for breeding
212
Treatment for sheep and goats with entropion
- Treat early before developing multiple issues
| - Affected animals should NOT be kept for breeding
213
Infectious keratoconjunctivitis in sheep and goats - most common agents?*** KNOW THIS
- Chlamydophila
- Mycoplasma
- Branhamella
- Moraxella bovis (IBK)***
214
What is the most likely agent in a goat with a cloudy eye?
- Chlamydophila percorum
215
Chlamydophila percorum and effects on goats and sheep
- Primary cause of KCS but also encephalitis, pneumonia, enteritis, polyarthritis, and abortions
216
When do chlamydia outbreaks occur with sheep and goats?
- Lambing
| - Confined, high stress
217
Reservoirs for chlamydia in sheep and goats
- Carriers
218
Immunity for chlamydia in sheep and goats
- Short-lived
| - Animals are re-infected
219
Can Chlamydia spread between goats and sheep?
- You bet it can
220
Signs of chlamydia in sheep and goats
- Epiphora, chemosis
- Serous/purulent discharge
- Lymphoid follicles
- Severe keratitis and edema
221
Diagnosis of chlamydia in sheep and goats
- PCR (gold standard)
| - Conjunctival cytology or culture
222
Treatment for chlamydia in sheep and goats
- Self-limiting
- Tetracyclines shorten the course of disease
- Always check FDA for current abx and treatment recommendations
223
Who gets mycoplasma keratoconjunctivitis?
- Older sheep
| - More common than chlamydophila in sheep
224
Clinical signs of Mycoplasma KCS in sheep?
- Blepharospasm, conjunctivitis, keratitis (corneal vessels), uveitis
225
Clinical signs of Mycoplasma KCS in goats?
- Corneal abscesses with panopthalmitis can occur +/- permanent damage
- Goats do NOT OFTEN have uveitis*
226
Diagnosis of Mycoplasma KCS?
- Conjunctival cytology
- Intracytoplasmic coccobacillary and ring shaped bodies in epithelial cells
- Culture and serology
227
Treatment for Mycoplasma KCS
- Self-limiting
- Tetracycline (oxytet topically or IM) in severe cases
- Some concern that use of tetracyclines promotes carriers in the herd
