Topical 5-fluorouracil as an adjunct treatment in equine corneolimbal squamous cell carcinoma

An 11-year-old crossbreed mare was presented with a nodular, pink mass at the temporal corneolimbal junction of the right eye. Histopathology confirmed the diagnosis of invasive squamous cell carcinoma. The mare underwent lamellar keratectomy and conjunctivectomy under general anaesthesia, followed by adjunctive topical chemotherapy with 1% 5-fluorouracil solution for 10 days post-operatively. Adverse effects included moderate conjunctival inflammation and exuberant granulation tissue formation at the surgical site, responding to surgical debulking and topical corticosteroid application. No mass regrowth was present at 12 months following discharge. This report describes the successful use of topical 1% 5-FU as an adjunctive treatment for equine ocular squamous cell carcinoma.     

Factors influencing morbidity and outcome of equine ocular squamous cell carcinoma

A retrospective review of 41 cases of equine ocular squamous cell carcinoma with follow up information for 33 horses is presented. An apparent prevalence in heavy horse breeds was identified. Age and sex distribution were similar to those previously reported. High recurrence (42.4 per cent) and low metastasis (6 per cent) rates were seen. Initial tumour location, primary treatment used, or patient case history had no apparent influence on final outcome. The willingness of owners to pursue with continuous treatment correlated with a high degree of success.     

Superficial keratectomy and topical mitomycin C as therapy for a corneal squamous cell carcinoma in a dog

A 10-year-old female West Highland white terrier was presented with refractory hyperplastic keratitis of the left cornea of one month's duration. At this time, a vascularised and rough lesion 5 mm in diameter was observed on the left cornea. No other abnormality was recognised on the affected eye. The corneal neoplasm was surgically removed and histologically diagnosed as a squamous cell carcinoma. For two months after the surgery, 0.04 percent mitomycin C (MMC) eye drops were applied as adjuvant chemotherapy. Primary corneal squamous cell carcinoma with no history of keratoconjunctivitis sicca is rare in dogs. In the present report, surgical removal of the neoplasm was combined with the topical administration of the anticancer drug mitomycin C and a good prognosis was obtained. The result indicates that the combination treatment used in this case may be an appropriate therapeutic choice for corneal squamous cell carcinoma in dogs.     

Challenges in the treatment of equine periocular squamous cell carcinoma

Management of periocular squamous cell carcinoma is challenging because of the need for adjunctive therapy, the adverse effects of therapies and the frequent recurrence of SCC. Appropriate treatment of equine ocular SCC usually involves surgical excision combined with adjunctive therapy selected as appropriate for the anatomic site of the lesion. Metastasis of periocular SCC has been reported to occur in approximately 6–15% of cases. The horse owner should be carefully educated to understand that for best long‐term results from the treatment of periocular SCC, they must be diligent in observing signs of recurrence or metastasis and be willing to have the horse examined as soon as adverse signs are observed. Furthermore, external beam radiation may be effective in the treatment of metastatic SCC and further clinical studies of this treatment modality are needed.     

A retrospective comparison of surgical removal and subsequent CO2 laser ablation versus topical administration of mitomycin C as therapy for equine corneolimbal squamous cell carcinoma

Objective To compare the complications and nonrecurrence rate following topical mitomycin C (MMC) therapy vs. CO₂ laser ablation for treating equine corneolimbal squamous cell carcinoma (SCC). Study design Retrospective study. Sample population Twenty‐five horses with corneolimbal SCC. Procedures Medical records of horses undergoing surgical tumor resection followed by either topical MMC therapy (0.04%) or CO₂ laser ablation between the years of 2004 and 2010 were reviewed. Recurrence and complications were compared between groups and within MMC subgroups defined by the time at which treatment was initiated relative to surgery. Results Therapy with topical MMC resulted in a nonrecurrence rate comparable to that achieved with CO₂ laser ablation (82.4% vs. 85.7%, respectively). Initiation of MMC following epithelialization of the surgical site a mean of 15 days postoperatively did not result in increased recurrence rates relative to treatment in the immediate postoperative period. Vision‐ or globe‐threatening complications tended to occur with greater frequency in horses receiving topical MMC in the immediate postoperative period (5 of 6 major complications) relative to following epithelialization of the surgical site (1 of 6 major complications). Conclusions Horses receiving adjunctive topical MMC therapy were no more likely to experience tumor recurrence than were horses undergoing CO₂ laser ablation in the horses in this study. Initiation of two to three rounds of MMC following epithelialization of the surgical site results in fewer major complications and achieves comparable disease resolution relative to treatment in the immediate postoperative period.     

Cryosurgical treatment of ocular squamous cell carcinoma of cattle.

A total of 718 ocular squamous cell carcinomas of cattle were treated with various cryosurgical units and techniques during a 2.5-year study. In 609 of the lesions, a single freeze was used, with a cure rate (total regression) of 66%. In 109 lesions treated with a double freeze-thaw cycle (rapid freeze to - 25 C, and unaided thaw followed immediately by refreezing to -25 C), the cure rate was 97%. Cryosurgical units designed for delivery of liquid nitrogen provided a more rapid rate of freezing and, thus, a higher cure rate than did units designed for delivery of nitrogen vapor. It was concluded that cryosurgery for treatment of squamous cell carcinoma is a simple and rapid procedure; is economical; provides analgesia itself, due to sensory nerve injury; requires minimal preoperative and no postoperative medication; causes minimal side effects; may be repeated; and is excellent for use on suspect premalignant lesions.     

Bovine ocular squamous cell carcinoma: an epidemiological perspective.

Epidemiological studies on bovine ocular carcinoma were reviewed. Reports on the frequency and the distribution of the disease indicate that it is still a very prevalent and economically important disease. It is recognized throughout North America, but is more frequent in lower latitudes under range conditions. Etiological factors including ultraviolet light, circumocular apigmentation and viruses, as well as the pathogenesis, are considered in light of current knowledge on carcinogenesis of this tumor. It is likely that the induction of bovine ocular carcinoma is multifactorial and the precise roles played by each of the various factors are not yet understood.     

A review of equine mucocutaneous squamous cell carcinoma

Squamous cell carcinoma (SCC) accounts for approximately 20% of all equine mucocutaneous (MC) tumours and continues to present a therapeutic challenge to practitioners. Most MC‐SCC are locally invasive and slow to metastasise, but metastasis to local lymph nodes is not uncommon. The most common location for MC‐SCC is the periorbital region, with the eyelid most commonly affected. Although only 13% of MC‐SCC involves the external genitalia, MC‐SCC is the most common neoplasm of male genitalia. Equine caballus papillomavirus‐2 has recently been linked to MC‐SCC and may prove to be necessary for tumour development. Risk factors may include chronic exposure to ultraviolet light and chronic skin irritation. Horses developing genital MC‐SCC tend to be older compared to those with periorbital MC‐SCC. Histopathology is required for definitive diagnosis of MC‐SCC, although horse phenotype and lesion location may suggest MC‐SCC. Several treatment modalities have been successful in eliminating or managing MC‐SCC, with surgical excision and intratumoural chemotherapy yielding the best results. Other treatment options including cryotherapy, hyperthermia, radiotherapy and photodynamic therapy are often used as adjunctive therapies. Early recognition of tumours and prompt intervention are associated with a positive outcome.     

Delayed metastasis of ocular squamous cell carcinoma following treatment in five horses

Identification of regional and/or distant metastasis following treatment and local resolution of primary ocular squamous cell carcinoma (SCC) was observed in 5 horses. In all cases, identification of metastasis occurred at least 18 months following treatment of the primary ocular lesions. In 3 cases, invasion of blood or lymphatic vessels by neoplastic cells was identified in the excisional biopsies of the primary tumour. Two horses developed SCC at 2 or more separate sites. At the time metastases were identified, there was no evidence of local recurrence of the ocular tumour in any of the horses. These cases confirm the importance of long‐term monitoring of horses for metastatic disease following treatment of ocular SCC even in the absence of local recurrence.     

Host response to bovine ocular squamous cell carcinoma

Specific humoral and cellular immunologic responses to autologous and heterologous tumors were evaluated in 35 Hereford cows with ocular squamous cell tumors and in 6 healthy cows. Sera from 5 healthy cows and 23 ocular tumor-bearing cows were evaluated for antibody to tumor, using radioimmunoassay, passive hemagglutination, agglutination, and microagglutination assays with various soluble tumor antigen and whole tumor cell preparations. Antibody to tumor was detected in only 2 cows. Using the microagglutination assay, antibody to autologous and heterologous tumor cells was found in the sera of 2 cows inoculated intraocularly with purified, viable autologous tumor cells. Twenty-eight tumor-bearing cows and 3 healthy cows were evaluated for delayed-type hypersensitivity responses, using 5 tumor preparations; positive skin test responses were not observed.     

Controlling ocular squamous cell carcinoma in Hereford cattle

In 3 herds 737 Hereford cattle were examined for neoplastic ocular lesions at intervals ranging from 20 to 242 days. Initially all lesions greater than 3 mm diameter were treated by cryosurgery; smaller lesions were left untreated. At subsequent inspections, lesions which had increased to 5 mm diameter were treated. The prevalence of ocular lesions in the herds ranged from 8.1 to 45.7% at the commencement of the study, and from 1.5 to 8.8% after 3.5 years. In treated cattle 71% of lesions regressed after one or two treatments. Seventy-five percent of the small untreated lesions regressed. The progression of lesions and occurrence of new lesions was highest during summer and lowest during winter. It was concluded that inspection of eyes for lesions should be at intervals of 3 to 4 months, and include one during the summer. It is feasible for owners to detect and identify cattle with ocular lesions and to present for treatment those that have grown since the preceding inspection to a size nearing or exceeding 5 mm diameter.     

Treatment of an ocular squamous cell carcinoma in a stallion with atrial fibrillation

A stallion was presented for surgical treatment of limbal squamous cell carcinoma. Excision with a conjunctival pedicle flap was done to prevent ocular invasion and preserve vision. A complication was the diagnosis of atrial fibrillation, which was not converted to sinus rhythm due to the potential complication of treatment with quinidine sulfate.     

Bovine ocular squamous cell carcinoma: Ultrastructural characteristics in vitro

The ultrastructure of cells obtained from bovine ocular squamous cell carcinoma is described. Cells were observed in pelleted form and in monolayer in situ on film liners. Both preparations consistently showed the ultrastructural features of transformed epithelium in vitro.