EYE CANCER IN CATTLE - Bovine Ocular Squamous Cell Carcinoma (BOSCC) and its Surgical Management.

Animals also  battle with cancer. This segment  is on Eye cancer in cattle.

Eye cancer in cow is a very painful and a fatal disorder which start as small nodular growth in the adnexa of eye. Squamous cell carcinoma is regarded as the most frequently diagnosed cancerous tumour in the bovines. Bovine ocular squamous cell carcinoma (BOSCC) represents the most economically important neoplasm in large animals. The malignant tendencies of this disease make early recognition critical.

I got opportunity to see  a wide variety of Ocular Squamous cell carcinoma cases in working bullocks and dairy cattle. UV rays from scrotching sunlight could be the main source of eye cancers  in working bullocks and free grazing dairy cattle especially in states like Maharashtra and northern Karnataka. 

Prolonged exposure to ultraviolet light, lack of pigment and lack of  hair at the affected site are common factors associated with the development 

of a squamous  cell carcinoma.These tumours in all species develops through a series of premalignant stages  before proceeding to carcinoma. Squamous cell carcinomas are solitary lesions , however  multiple tumours may develop in conjunction with solar injury.Human negligence and callous attitude can lead to severe inflicting injuries to the eye which ultimately culminates in eye cancer. 

I would like to share my experience during my tenure in Animal Rahat, PETA , the largest working animal welfare organization dedicated for working bullocks. We witnessed many animals in a northern Maharashtra village with eye cancer on the right eye. When enquired , it was a shocking finding that the abuse of the eyes by rubbing a combination of pepper and salt to make the animals run during bullock races and sugarcane season had led to high incidence of eye cancer . I am of the opinion that Willful persuasive extension education should be part and parcel of the veterinary practice and I strongly believe that it is the duty of every vet to educate the animal owner / farmer about what the animal is going through. Thus eye cancer  not only drastically reduce the performance of the animal and considerable economic importance to the farmer , but also has serious welfare constraints in animal ethology point of view.The cancer growth may start at the medial canthus, lateral canthus or on eyelid . 

Third eyelid is the most common site of origin of eye cancer.  The stage of presentation of the case decides the chances of saving an affected eye.

Cases presented in initial stages can be fully recovered and the eyes can be saved. But many cases come in advanced chronic stage with extensive tumor mass eating up the entire globe.

Treatment of cancer eye depends on its location and the degree of involvement of ocular  structures. Veterinarians easily remove lesions on the third eyelid by cutting out the free  border of the third eyelid using local anesthesia and tranquilization. Lesions removed in this way are very unlikely to recur. Applying hyperthermia (high temperature) or cryotherapy (freezing) to kill the remaining tumor cells in the tissue of the lids but the procedure can not be employed for all cancers.

Three terms are widely used by the veterinarian in this context are Extripation or Exenteration, Evisceration, Enucleation

Enucleation is removal of the entire globe, including the cornea, sclera, and a portion of the optic nerve .

Evisceration surgery involves removal of the contents of the globe while leaving the sclera and optic nerve in place. The cornea can be retained in some evisceration cases.

Exenteration of Eye or  Extripation of Eye ball  is the removal of the globe, as well as the complete or partial removal of the soft tissues of the orbit.

 The ultimate goals of these surgeries are to safely and effectively remove the diseased eye or orbital contents using advanced surgical techniques, eliminate the severe underlying ocular pathology

 Removal of the entire eyeball is indicated when tumors have spread to the extent that the eyeball is blind; the tumor has invaded deeper structures surrounding the globe; or the eyelid is involved to the extent that it cannot be repaired after removal of the tumor. It may appear to be a drastic procedure, but success of the extirpation is to  accomplish it quickly and humanely.

ANETSHESIA AND RESTRAINT

I prefer standing surgery as the wonderful cock tail of Butorphanol, Xylazine Ketamine @ 0.01,0.2 and 0.04 mg/ kg bw Intra muscular troute will give excellent sedation for 30 minutes. Four point retrobulbar block ensures a painless surgical procedure equally rewarding for the surgeon and for the animal.

YOU CAN WATCH THE VIDEO BELOW

Exenteration of Eye ball 

REGIONAL ANESTHESIA OF EYE IN CATTLE

4 Point Retrobulbar Nerve Block: The 4-point retrobulbar block is technically easier and can be done more rapidly as compared with the Peterson eye block. In this technique, an 18 gauge, 9-cm long needle is introduced through the skin on the dorsal, lateral, ventral and medial aspects of the eye, at 12, 3, 6, and 9 o´clock positions, respectively. Introduction of the needle through the

conjunctiva should be avoided to reduce the occurrence of ocular contamination. The needle is directed behind the globe using the bony orbit as a guide. When the needle is introduced into retrobulbar sheath, the eye will move slightly with the tug of the  needle. After this location is reached and aspiration is performed to assure that the needle is not in a vessel, 5-10 milliliters of lidocaine (2%) is deposited at each site. Mydriasis indicates a successful block.

Other ocular nerve blocks in cattle are

Auriculopalpebral Nerve Block: The  auriculopalpebral nerve can be palpated as it crosses the zygomatic arch, roughly 5-6 centimeters behind the supraorbital process. Inject 5 milliliters of 2% lidocaine HCl subcutaneously on the dorsal aspect of the zygomatic arch at this location.

Peterson Nerve Block: This is a complicated one .

After performing a small local skin block over the intended site of puncture, a 3.8-cm long 14 gauge needle is inserted through the skin as a cannula for introduction of an 18-gauge 9-cm long needle for the nerve block. The cannula is inserted caudal to the junction of the supraorbital process and zygomatic arch and is introduced through the skin. Then, the 18-gauge, 9-cm long needle is introduced through the cannula needle and is directed in a horizontal and slightly dorsal direction until the  coronoid process is encountered. The needle is “walked off” the rostral aspect of the coronoid process and advanced in a ventromedial direction along the caudal aspect of the orbit until the needle encounters the bony plate encasing the foramen orbitorotundum. Once the needle is advanced to the foramen, it is advised that the needle be drawn back  a few millimeters to reduce the risk of intrameningeal injection. After aspirating to assure the needle is not in the internal maxillary artery, 10-15 milliliters of lidocaine (2%) is deposited, with an additional 5 milliliters of lidocaine deposited as the needle is slowly withdrawn. Mydriasis indicates a successful block.

Retrobulbar block: An alternative to the 4-point retrobulbar block is the single retrobulbar block In this technique, the 9-cm long 18-gauge needle is bent into a ½ circle. The needle is inserted immediately ventral to the dorsal orbital rim and directed such that the needle impacts into the bone of the orbit. Then the needle is advanced as it is rotated ventrally in a progressive

manner such that the needle remains in close proximity to the bone. After the needle is inserted to the caudal aspect of the eye, 20 ml of 2% lidocaine HCl is administered after aspiration to ensure that the needle is not positioned in a vessel or other fluid structure. Successful deposition of lidocaine causes mild proptosis of the globe.

Ring Block: Additional local anesthesia of the eyelids is recommended as the Peterson and retrobulbar blocks typically  result in incomplete analgesia of the eyelids. Five to ten milliliters lidocaine (2%) is infiltrated subcutaneously 2.5 centimeters from the eyelid margins as a ring block.

Surgical procedure of Exenteration

A transpalpebral ablation technique is utilized to remove the eye. The upper and lower eyelids are sutured closed or  alternatively, eyelids can be closed using multiple towel . A circumferential skin incision is made approximately 1 centimeter from the edges of the eyelids . Using a combination of blunt and sharp dissection, Mayo scissors are used to dissect through the orbicularis oculi muscle, fascia, and subcutaneous tissue surrounding the eye. The interior of the bony orbit is used as a guide. The medial and lateral canthal ligaments are sharply transected to allow access to the caudal aspect of the orbit.

As there is a large vessel associated with the medial canthus and optic stalk which need to be ligated after the resection. A vascular clamp can aid in hemostasis while additional excision

of remaining orbital tissue is undertaken. In cases where neoplastic infiltration of the bony orbit has occurred, affected areas of ocular periosteum should be thoroughly excised. I had not encountered any bony lesions extending from BOSCC so far.

The skin incision can be closed in a variety of patterns with a nonabsorbable suture such as No. 3 nylon. Common patterns include the Ford interlocking, cruciate or simple continuous after sufficiently obliterating the dead space with iodine impregnated gauze rolls. This needs to be changed for 5 dyas till the cavity dries and heals up.   

Post-operative Care: The animal should be kept in a confined area for several days after surgery to allow for appropriate hemostasis to occur. Daily observation of the surgical site and assessment of general well being is recommended until suture removal. Sutures should be removed in 14 to 21 days to allow for complete healing of the skin. 

Histopathologically infiltrating tumour cells characterized by  numerous mitotic figure, diffusely dilated lymphatics along with Multifocal necrosis and haemorrhages throughout  the neoplasm is a common feature