Much of what you know about SCC (squamous cell carcinoma) in other species translates to cattle and horses, particularly in terms of risk factors and metastatic activity. SCC affects older, light skinned (white faced) animals exposed to UV radiation. Papilloma virus may start a lesion, particularly when combined with UV irradiation. SCC is locally invasive but very slow to metastasize. Local lymph nodes may be enlarged due to tumor spread or, more likely, related to local inflammation.
- Limbus (corneal-scleral junction)
- Third eyelid
- Upper and lower eyelid margins
Male horses (stallions and geldings) with ocular SCC should be checked for penile SCC, as well. While UV light isn’t directly an issue, there is definitely a correlation.
White faced cattle with a dark ring around their eye are less likely to get SCC than those with a white ring based on research by KM Davis et al.
Treatment options include
- hyperthermia, photodynamic or radiation therapy
- only some referral institutions will have this capability
- mass removal – blade or laser
- Lasers are typically only found in referral institutions
- Surgical removal (cutting it out) can be very tricky to do effectively and leave functional eyelids that can close. A specialist is often indicated as the eyelids scar very easily and this deforms the lid margin.
- Cryotherapy can also lead to scarring and deformed lid margins; this should also be used by specialists for both corneal and lid lesions
- This is the primary field option
Cattle with cancer eye or with enucleations will be carefully inspected at slaughter. Generally the head will be condemned. The carcass is less likely to be condemned with a healed enucleation site.
- White animals are prone to SCC
- SCC tends to start on the lids or the limbus and is locally invasive but slow to metastasize
- Eye removal doesn’t usually affect slaughter options unless the lymph nodes are enlarged; a nasty eye creates more issues
Bovine ocular SCC in Italy– VETERINARSKI ARHIV 84 (5), 449-457, 2014- same pathogenesis applies in the US
Bovine Ocular SCC – VCNA,2010- skim the headings to see which parts might help you answer questions
slaughter info-compilation of notes
Bovine welfare issues – eye disorders, 2010 VCNA
the use of liquid nitrogen to create very cold temperatures that cause cell destruction via ice crystal formation