Disorders of the Bovine eye

Question 1

If an ulcer extends all the way to the sclera, what is the likely etiology?

Answer 1

Trauma/Foreign body

Question 2

What is the main infectious eye condition that is worried about in cattle?

Answer 2

Infectious bovine keratoconjunctivitis

Question 3

What are some other infectious causes of eye lesions in cattle?

Answer 3

Infectious bovine rhinotracheitis conjunctivitis, malignant catarrhal fever keratoconjunctivitis, listeriosis, bovine viral diarrhea, ocular signs of neonatal septicemia

Question 4

Why is pinkeye such an economically important condition of cattle?

Answer 4

It results in significantly lower weaning weights (about 20 lbs) as calves spend less time eating due to pain

Question 5

What other costs are associated with pinkeye in cattle?

Answer 5

Decreased milk production in cows, sale discounts due to scarring, decreased value of breeding stock, treatment costs, prevention costs, welfare costs

Question 6

Are there any long term effects of pinkeye after resolution?

Answer 6

Yes, decreased muscle area and fat thickness even at a year old

Question 7

What bacteria is responsible for pinkeye?

Answer 7

Moraxella bovis, Moraxella boviculi may be a secondary invader

Question 8

Name some of the features that increase pathogenicity of moraxella bovis

Answer 8

Pilli (Q enhances attachment of bacteria to corneal cells, I enhances local persistence and establishment of infection), cytotoxins (beta hemolytic, corneotoxic, leukotoxic, hydrolytic/proteolytic) which cause pore to form through cornea

Question 9

What two concurrent infections can lead to significantly more damage in pinkeye cases?

Answer 9

Mycoplasma, infectious bovine rhinotracheitis

Question 10

How are most cattle affected by pinkeye?

Answer 10

Carrier animals

Question 11

What can cause the corneal irritation that assists bacteria in entering the eye?

Answer 11

UV damage to the cornea, scarification by dust, plant material, feeds, female face fly

Question 12

During what season are pinkeye infections most common?

Answer 12

Summer > Spring/Fall > Winter

Question 13

What nutritional deficiencies may contribute to severity of pinkeye infections?

Answer 13

Protein and energy, vitamin A, copper and selenium

Question 14

What are the main clinical signs associated with pinkeye infections?

Answer 14

Scleral injection, corneal edema, central corneal ulcer, excessive lacrimation, neovascularization, photophobia/blepherospasm

Question 15

How will the eye look different long term after pinkeye infection?

Answer 15

there will always be a scar present, may get better over time

Question 16

What are some occasional sequele to pinkeye?

Answer 16

Secondary glaucoma with bupthalmos (trt-drain anterior chamber and let lens fall out), blindness

Question 17

What type of vaccine is the m bovis vaccine? Is it effective?

Answer 17

Killed Bacterin and autogenous vaccine
- none are proven effective

Question 18

What are the treatment options for pinkeye?

Answer 18

Topical- often not practical

Bulbar scleral injections- penicillin procaine G +/- dexamethasone

Question 19

What drugs are labeled for systemic use in pinkeye cases?

Answer 19

Oxytet 200 SQ

Draxxin SQ

Question 20

What extralabel uses of drugs is commonly used for pinkeye cases?

Answer 20

Nuflor, excede
-both show evidence at reducing ulcer healing time

Question 21

What practices can be implemented to help protect against pinkeye?

Answer 21

Fly control (pour ons, spraying, fly tags), pasture management (bush hogging, weed control), feeding management (keeping hay from being fed where cattle are allowed to “dig”), UV protection (provide shade)

Question 22

What ocular sign does mycoplasma cause?

Answer 22

conjunctivitis

Question 23

What ocular sign does infectious bovine rhinotracheitis cause?

Answer 23

conjunctivitis, ocular discharge, corneal edema, neovascularization

Question 24

What ocular sign does malignant catarrhal fever cause?

Answer 24

photophobia, epiphora, episcleral injection and scleritis, conjunctivitis, keratitis with edema and neovascularization, anterior uveitis, exopthalmia

Question 25

What ocular sign does listeriosis cause?

Answer 25

unilateral facial nerve paralysis and ptosis which can lead to keratoconjunctivitis

Question 26

What ocular sign does bovine viral diarrhea cause?

Answer 26

Retinal dysplasia, cataracts, micropthalmia, optic neuritis

Question 27

What ocular sign does neonatal septicemia cause?

Answer 27

Miosis fibrin deposition in anterior chamber, hypopeon and hyphema

Question 28

What is the main neoplasia affecting the bovine eye?

Answer 28

Squamous cell carcinoma

Question 29

What is the leading cause of whole carcass condemnation in the US?

Answer 29

Squamous cell carcinoma

Question 30

What are the costs associated with SCC?

Answer 30

Treatment costs, decreased production, early culling, animal welfare

Question 31

What are the preferred locations of SCC?

Answer 31

Conjunctiva, corneoscleral junction, nictitating membrane, cornea, eyelid

Question 32

What are some risk factors for the development of SCC?

Answer 32

Age- 7-8 year olds most commonly affected
UV light- white faced cattle most affected
Breed- herefords and hereford crosses (black baldies), hosteins
Genetics

Question 33

What are some possible viral components to SCC?

Answer 33

Herpes virus and papillomavirus

Question 34

What are the 4 stages of SCC in cattle?

Answer 34

Stage 1- plaques
Stage 2- keratomas/keratocanthomas
Stage 3- papillomas
Stage 4- carcinomas (ability to metastasize)

Question 35

What stage should you cull for SCC cases?

Answer 35

Stage 4. If uncomplicated condemn head, if complicated with extension into lungs and lymph nodes condemn whole carcass

Question 36

What are the treatment options for stages 1-3 SCC lesions?

Answer 36

1. Surgical exision (keratectomy, 3rd eyelid removal, exteneration, venreal eyelid papilloma removal)- 90% cure rate
2. Cryotherapy- lesion has to be <2.5 cm but 60-90% efficacy
3. Hyperthermia- 90% cure rate, lesion has to be <2.5 cm, use hashtag technique

Question 37

Compare/contrast the indications for enucleation compared to exteneration

Answer 37

Enucleation- infection within the globe, glaucoma, globe rupture

Exeneration: ocular neoplasia >2.5 cm