Disorders of the Bovine Eye Flashcards
what is the primary infectious disease of the bovine eye?
infectious bovine keratoconjunctivitis (aka pinkeye)
what is the primary neoplastic disease of the bovine eye?
squamous cell carcinoma (aka cancer eye)
how can you differentiate ulcers created by trauma/FB from ulcers created by infectious bovine keratoconjunctivitis?
in cases of trauma/FB, the ulcer will be at the edge of the sclera
in cases of IBK, they will be CENTRAL
IBK is the MAJOR infectious etiology for bovine ocular disease. What are other MINOR disorders?
- infectious bovine rhinotracheitis conjunctivitis
- malignant catarrhal fever keratoconjunctivitis
- listeriosis
- bovine viral diarrhea (causes retinal dysplasia, cataracts, micropthalmia, and optic neuritis)
- neonatal septicemia
why should producers care about infectious bovine keratoconjunctivitis?
it is extremely painful and can cause the cattle to be anorexic. This will decrease gains, cause weight loss, and decrease production. Additionally, it can cause sale discounts (d/t scarring), decreased value of breeding stock, and is associated with treatment and prevention costs.
also, its not nice to the animals welfare :(
Does having pinkeye before weaning affect production traits as a yearling?
yes. The calves recovered and tried to catch up in gains, but they had overall less ADG, less fat, less muscle, and weighed less.
What pathogen is mainly involved in IBK?
moraxella bovis
+/- moraxella boviculi
what is the function of moraxella bovis’s pili?
the Q pili enhance attachment of the bacteria to the corneal cells
the I pili allow for local persistence and establishment of infection
What feature of moraxella bovis leads to corneal ulcers, corneal edema, and cell lysis within the eye?
cytotoxins (B-hemolytic, corneotoxic, leukotoxic, and hydrolytic/proteolytic)
they cause corneal epithelial cell lysis and form ulcers
They cause lysis of neutrophils and release of enzymes that cause corneal edema
and they damage membrane phospholipids causing cell lysis.
why are vaccines not that effective for pink eye?
the vaccines target the bacterial pili
the bacterial pili are constantly changing.
T/F: moraxella bovis can be assisted by any previous damage created by infection with mycoplasma and/or IBR
true
T/F: there are cattle who are carriers of moraxella bovis and this is the source of infection for all other cattle
false – there are carriers, but you must have secondary irritation to the cornea (UV damage, scar by dust, plant, seeds, or female face flies) for moraxella to penetrate the defense mechanisms of the eye.
what are the clinical signs of pinkeye?
first: epiphora
corneal edema
central corneal ulcer
excessive lacrimation
scleral injection
photophobia/blepharospasm
neovascularization
How do you treat a patient with secondary glaucoma with bupthalmos from a severe IBK lesion? This patient is blind.
apply proparacaine on the eyeball
lance the eye with a scalpel and allow the lens to fall out
apply fly spray
T/F: an autogenous vaccine (made from cows themselves) can be created for IBK
true
How many M. bovis vaccines are currently commerically available?
15 killed bacterin vaccines
none of which are effective
T/F: topical therapy is not practical for IBK treatment
true it would have to be applied multiple times a day
what is the recommended treatment for IBK?
bulbar scleral injections of penicillin procaine G +/- dexamethasone
can also inject: oxytet 200 SQ or Draxxin SQ (both on label). and Nuflor SQ or Excede SQ (both extralabel and require veterinary oversight)
What are preventative practices you can do for IBK?
- fly control
- pasture management
- feeding management
- UV protection
T/F: Squamous cell carcinoma is spontaneous
true
there are also risk factors tho
What is the leading cause of whole carcass condemnation in the US?
squamous cell carcinoma
what are the 5 preferred locations for squamous cell carcinoma?
conjunctiva
corneoscleral junction
nictitating membrane
cornea
eyelid
What are the 4 risk factors for squamous cell carcinoma?
- Age (older 7-8y)
- UV light (more prev in white face cattle)
- Breed (hereford, holsteins)
- Genetic inheritance
What are the 2 viral components of squamous cell carcinoma?
- herpes (intranuclear inclusions have been found in cancer eye lesions)
- papillomavirus (may be precursor lesion formation)
