Squamous cell carcinoma (SCC) is a type of malignant tumor that arises from squamous epithelial cells, commonly affecting horses' skin, eyes, and mucous membranes. It is one of the most frequently diagnosed cancers in equine species. This carcinoma is associated with prolonged exposure to ultraviolet light, particularly in areas with minimal pigmentation or hair coverage. SCC can present as ulcerated lesions or proliferative masses and may lead to local tissue destruction and metastasis if untreated. Diagnosis typically involves clinical examination, biopsy, and histopathological analysis. Treatment options vary depending on the tumor's location and stage and may include surgical excision, cryotherapy, or chemotherapy. This section aggregates peer-reviewed studies and scholarly articles that explore the pathogenesis, risk factors, diagnostic methods, and treatment approaches for squamous cell carcinoma in horses.
Michau TM, Davidson MG, Gilger BC.  To determine the complications and nonrecurrence rates following superficial lamellar keratectomy, bulbar conjunctivectomy, and adjunctive carbon dioxide (CO(2)) photoablation for corneolimbal squamous cell carcinoma (SCC) in the horse. Methods:   Retrospective study. Sample population  Twenty-four horses with corneolimbal SCC. Methods:   Medical records of horses diagnosed with corneolimbal SCC that was surgically excised and where CO(2) photoablation was used as an adjunctive therapy from 2000 to 2007 were reviewed. Signalment, prior therapy, tumor location and size, complications,...
Clode AB, Miller C, McMullen RJ, Gilger BC.  To compare the complications and nonrecurrence rate following topical mitomycin C (MMC) therapy vs. CO(2) laser ablation for treating equine corneolimbal squamous cell carcinoma (SCC). Methods:   Retrospective study. Methods:   Twenty-five horses with corneolimbal SCC. Methods:   Medical records of horses undergoing surgical tumor resection followed by either topical MMC therapy (0.04%) or CO(2) 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 ...
Labelle AL, Metzler AG, Wilkie DA.Neoplasia, for which surgical excision is a frequent treatment, is the most common disease of the equine nictitating membrane. There is little long-term follow-up information available to the practitioner regarding the long-term effects of nictitating membrane excision on ocular health. No information is available to compare recurrence of primary neoplasia of the nictitating membrane after excision with local or general anaesthesia. Objective: To evaluate the long-term complications of nictitating membrane resection in horses; recurrence of neoplasia of the nictitating membrane when nictitatin...
Corapi WV, Birch SM, Carlson KL, Chaffin MK, Snowden KF.CASE DESCRIPTION-A 22-year-old American Paint Horse gelding from the Gulf Coast region of Texas was evaluated for regrowth of a perirectal squamous cell carcinoma that had been surgically removed 11 months previously. CLINICAL FINDINGS-A necrotic and ulcerated mass was present below the anus. The horse had paraphimosis and was having difficulty with urination. Histologic examination of the mass revealed that it was squamous cell carcinoma, and the horse was euthanized because of the unlikelihood that the mass could be adequately resected and its close proximity to the urethra. OUTCOME-At necro...
Kainzbauer C, Rushton J, Tober R, Scase T, Nell B, Sykora S, Brandt S.In January 2010, 18 months after excision of an ocular squamous cell carcinoma (SCC), a Connemara mare presented with anorexia and periorbital/parotideal lesions. Post mortem examination revealed these lesions as forming one entity, with 2 additional growths in the retropharyngeal region and the left jugular groove, respectively. The lesions were confirmed histopathologically as SCCs. Using PCR, peripheral blood mononuclear cells (PBMCs) from 2008 and 2010, tumour tissue, intact skin and vulval mucosa were screened for Equus caballus papillomavirus type 2 (EcPV-2) and bovine papillomavirus typ...
Knight CG, Munday JS, Rosa BV, Kiupel M.A 9-year-old gelding presented with approximately 100 papillomas that covered about 75% of the distal penis. Biopsy was performed, and histology showed evidence of viral cytopathic change and koilocytosis. Polymerase chain reaction using DNA extracted from biopsied tissue amplified equine papillomavirus type 2 (EcPV-2) DNA sequences. Sixteen months later, the horse was re-examined and the appearance of the papillomas was unchanged. Equine papillomavirus type 2 DNA sequences were again amplified from both biopsied tissue and swabs of the penis. Papillomavirus was localized to the lesions by imm...
Knight CG, Munday JS, Peters J, Dunowska M.Forty cases of equine penile disease were screened with polymerase chain reaction for the presence of papillomaviral DNA. Cases consisted of 20 squamous cell carcinomas (average age of horse, 23.9 years) and 20 non-squamous cell carcinoma diseases (average age of horse, 13.3 years). All horses but one originated from the Northeastern United States. Breeds were not recorded. As based on MY09/MY11 consensus primers, DNA sequences from equine papillomavirus type 2 were amplified from 9 of 20 horses (45%) with penile squamous cell carcinoma and only 1 of 20 horses (5%) with non-squamous cell carci...
Scase T, Brandt S, Kainzbauer C, Sykora S, Bijmholt S, Hughes K, Sharpe S, Foote A.The aetiology of genital squamous cell carcinoma (SCC) in horses remains unknown, but the similarity to the disease in man, for which papillomavirus infection has been shown to be a causal factor, requires to be investigated in horses. Objective: One or more novel papillomaviruses cause equine genital SCC and its associated premalignant lesions. Methods: DNA was extracted from samples of equine genital SCC and performed rolling circle amplification, in order to identify closed circular DNA viral genomes within the samples. The amplified DNA was subcloned and sequenced and the DNA sequence comp...
Van Den Top JG, Ensink JM, Gröne A, Klein WR, Barneveld A, Van Weeren PR.Penile and preputial tumours are not uncommon in the horse, but can cause discomfort and lead to serious complications. Several types of tumour of the male external genitalia have been described. The most common type is the squamous cell carcinoma (SCC), which is found mainly in older horses. Reports of a breed predilection for penile tumour formation are equivocal, but castration, coat colour, poor hygiene and various infectious agents have all been suggested to predispose to the development of some types of tumour (e.g. SCC, papilloma and melanoma). Careful assessment of the primary tumour i...
Giuliano EA.Neoplastic adnexal disease represents one of the most frequently encountered and therapeutically challenging ophthalmic problems of horses. This paper reviews current concepts in equine periocular neoplasia. Specifically, a literature-based review of the aetiopathogenesis of the most common tumours to affect the equine eyelid (squamous cell carcinoma, sarcoid, melanoma and lymphosarcoma) is provided. Current and emerging treatment modalities, including photodynamic therapy, are reviewed.
Malalana F, Knottenbelt D, McKane S.Ocular lesions in horses, confirmed as squamous cell carcinoma, were treated topically with mitomycin C. Fourteen horses with confirmed ocular squamous cell carcinoma, three of which were affected bilaterally, were included in the study. Eight of the affected eyes were treated topically with mitomycin C alone; in the other nine eyes, the tumours were surgically removed and topical treatment with mitomycin C was then applied. The treatment protocol consisted of 0.2 ml of 0.04 per cent mitomycin C instilled into the conjunctival sac of the affected eye, every six hours, in rounds of seven days o...
Vanderstraeten E, Bogaert L, Bravo IG, Martens A.Squamous cell carcinoma (SCC) represents the most common malignant tumour of the eye and external genitals in horses. Comparable to humans, papillomaviruses (PV) have been proposed as etiological agents of cancer in horses and recently, Equine papillomavirus type 2 (EcPV2) has been identified in genital SCCs. Hitherto it had never been demonstrated in ocular SCCs. The first goal of this study was to determine the prevalence of EcPV2 DNA in tissue samples from equine genital and ocular SCCs, genital papillomas and penile intraepithelial neoplasia (PIN) lesions, using EcPV2-specific PCR. The sec...
Payne RJ, Lean MS, Greet TR.Between October 2000 and January 2007, 24 horses were presented with suspected squamous cell carcinoma (SCC) of the third eyelid. The hospital's medical records were analysed retrospectively to gain data about the cases, and telephone follow-up was obtained from the owners and referring veterinary surgeons. The resected third eyelid was submitted for histological examination in 21 cases; in the other three cases the tissue was not submitted at the owners' request, for economic reasons. SCC was confirmed in 16 of these 21 cases, three cases were diagnosed histologically as lymphoid hyperplasia,...
Taylor SD, Haldorson GJ, Vaughan B, Pusterla N.Gastric neoplasia of horses is incompletely described. Objective: Provide history, clinical signs, and clinicopathological and pathological findings associated with gastric neoplasia in horses. Methods: Twenty-four horses with gastric neoplasia. Methods: Retrospective study. History, clinical signs, and clinicopathological and pathologic findings in horses diagnosed histologically with gastric neoplasia were reviewed. Results: Horses ranged in age from 9 to 25 years (median 18 years at presentation). There was no apparent breed or sex predisposition. The most common presenting complaints were ...
Barabas K, Milner R, Lurie D, Adin C.Cisplatin is a platinum chemotherapeutic used in a variety of malignancies. The antineoplastic activity occurs from DNA cross-links and adducts, in addition to the generation of superoxide radicals. Nephrotoxicity is the most well-known and potentially most clinically significant toxicity. Unfortunately, the mechanism for cisplatin nephrotoxicity has not been completely elucidated; however, many theories have been developed. Other toxicities include gastrointestinal, myelosuppression, ototoxicity and neurotoxicity. Saline diuresis is currently the most accepted way to prevent cisplatin nephrot...
Kafarnik C, Rawlings M, Dubielzig RR.To describe the pathomorphological features of corneal stromal invasive squamous cell carcinoma (CSI-SCC) in horses. Methods: A total of 87 equine SCC in the Comparative Ocular Pathology Laboratory of Wisconsin database were retrieved. The signalment and anatomical distribution were summarized. Ten CSI-SCC out of 87 SCCs were further investigated focusing on pathomorphological description. All 10 cases were stained with H&E, periodic acid-Schiff stain and Verhoeff's elastic stain. Results: Four Appaloosas, two Quarter horses, two American Paint, one Pinto and one Thoroughbred horse were affect...
Giuliano EA, MacDonald I, McCaw DL, Dougherty TJ, Klauss G, Ota J, Pearce JW, Johnson PJ.Local photodynamic therapy (PDT) is a novel cancer therapy in veterinary ophthalmology. A prospective pilot study seeking to demonstrate proof of principle and safety for the treatment of equine periocular squamous cell carcinoma (PSCC) was therefore conducted. We hypothesized that surgical excision with adjunctive local PDT is an effective and safe treatment for equine PSCC. Methods: Nine horses (10 eyes) with PSCC were treated with surgical resection, local infiltration of resulting wound beds with 2-[1-hexyloxyethyl]-2-devinylpyropheophorbide-a (HPPH) and irradiation with 665-nm wavelength ...
Smith KM, Scase TJ, Miller JL, Donaldson D, Sansom J.To investigate whether cyclooxygenase-2 (COX-2) is expressed by equine ocular and adnexal squamous cell carcinomas (SCC). Methods: Forty-three samples of histologically confirmed cases of ocular SCC or carcinoma in situ (CIS) from 34 horses presented to the Animal Health Trust between 1992 and 2004 were subjected to a standard, two-layered, indirect immunohistochemical method using a rabbit polyclonal antihuman COX-2 antibody. Ten formalin-fixed, paraffin-embedded tissue samples taken from recognized predilection sites for SCC, from the grossly normal eyes of 10 horses euthanized for reasons u...
Thamm DH, Ehrhart EJ, Charles JB, Elce YA.The enzyme cyclooxygenase-2 (COX-2) is expressed in some tumor and stromal tissues, and catalyzes production of prostaglandins with growth stimulatory, antiapoptotic, proangiogenic, and immunosuppressive properties. Pharmacologic inhibition of COX-2 is associated with antitumor activity in various human and canine malignancies. The purpose of this study was to assess COX-2 expression in a series of equine sarcoids, melanomas, and squamous-cell carcinomas (SCC). COX-2 expression was assessed in formalin-fixed paraffin-embedded tissues from 14 sarcoids, 11 melanomas, and 37 SCC that represent va...
Steinbach F, Bischoff S, Freund H, Metzner-Flemisch S, Ibrahim S, Walter J, Wilke I, Mauel S.Dendritic cells (DCs) are antigen-presenting cells, which are well known for their capacity to stimulate immunity. The ex vivo generation of myeloid DC from monocytes has facilitated the development of DC-vaccination protocols which have been extensively evaluated in tumour immunology and are regarded by some as a gold mine for clinical research. However, there is a considerable amount of work required to overcome the potential risks associated with such therapy. It is therefore mandatory to characterize the system to be applied and to study the reactions, particularly at the level of T cell r...
Nasir L, Campo MS.Bovine papillomavirus (BPV) is perhaps the most extensively studied animal papillomavirus. In cattle BPVs induce benign tumours of cutaneous or mucosal epithelia, called papillomas or warts. Cattle papillomas are benign tumours and generally regress without eliciting any serious clinical problems in the host, but occasionally persist and provide the focus for malignant transformation to squamous cell carcinoma, as in the case of cancer of the urinary bladder and cancer of the upper alimentary canal. BPV is the only papillomavirus that jumps species: the virus also infects equids, and gives ris...
van den Top JG, de Heer N, Klein WR, Ensink JM.The most common penile and preputial neoplasm in the horse is the squamous cell carcinoma (SCC), but no large surveys of treatment and effects of the grade of the tumour, based on the degree of differentiation, on outcome of affected horses are available. Objective: Analysis of treatment of male horses affected with SCC of the external genitalia and long-term results of treatment. Methods: Seventy-seven cases of SCC were evaluated. Data recorded included treatment, outcome, post operative histopathology and retrospective tumour grading. Results: Treatments included: cryosurgery, excision, part...
van den Top JG, de Heer N, Klein WR, Ensink JM.Preputial and penile tumours are more common in horses than in other domestic animals, but no large surveys of male horses with tumours of the external genitalia are available. Objective: To present a retrospective analysis of male horses with neoplasms of the external genitalia. Methods: The penile and preputial tumours of 114 horses were evaluated. Data recorded included age, gelding or stallion and breed; type and site of lesion; involvement of regional lymph nodes; histopathology (including grading of squamous cell carcinoma); and results of radiographic examination of the thorax. Results:...
Sandmeyer LS, Panizzi L, Grahn BH.The research article deals with a case study of an 18-year old male horse suffering from an enlarging mass on its right lower eyelid, which was examined and diagnosed at […]
Rassnick KM, Njaa BL.Squamous-cell carcinoma (SCC) is the second most common tumor in horses, and 40%-50% may occur in ocular and adnexal structures. Cyclooxygenase (COX)-2 is an inducible enzyme responsible for the production of prostaglandins that control cell growth and the development and progression of cancer. Mechanisms responsible for the initial upregulation of COX-2 in neoplasia are unclear; prolonged sunlight exposure and mutations in the p53 gene may be possibilities. Because the etiopathogenesis of ocular SCC in horses may involve ultraviolet sunlight and p53 mutations, the purpose of this study was to...
Junge RE, Sundberg JP, Lancaster WD.In a retrospective study encompassing 13 years of diagnostic work, papillomas and squamous cell carcinomas from horses were screened for papilloma-virus antigens, using the peroxidase-antiperoxidase technique. Papillomas were most commonly found on the penis and vulva, followed by cutaneous, ocular, and oral locations. Squamous cell carcinomas were most frequently located on the third eyelid and cornea, followed by genital, oral, maxillary sinus, and cutaneous sites. Papillomavirus structural antigens were detected in 7 cutaneous and 5 genital papillomas, but not in squamous cell carcinomas.
English RV, Nasisse MP, Davidson MG.Limbal squamous cell carcinoma in 4 horses was treated successfully, using carbon dioxide laser ablation. Tumors were removed, with minimal to no postoperative inflammation or discomfort to the horses. Carbon dioxide laser ablation represents a promising new option in the treatment of limbal squamous cell carcinoma in horses.
Rayner SG, Van Zyl N.To assess the effectiveness of topical mitomycin C application as an alternative adjunctive therapy to CO2 laser ablation in the treatment of equine ocular squamous cell carcinoma. Methods: A retrospective clinical study of eight client owned horses in which 10 affected eyes were treated for ocular squamous cell carcinoma over a 17 month period. (March 2003 to August 2004). Methods: Each horse was given a general anaesthetic to allow CO2 laser ablation of the lesion(s). Mitomycin C at a concentration of 0.4 mg/mL was then applied intraoperatively to the affected areas for 1 or 5 minutes. Posto...
Garma-Aviña A.A series of 40 tumors with a proven diagnosis of squamous cell carcinoma for which both histology and cytology were available were classified according to their histologic appearance as well differentiated, moderately differentiated, and poorly differentiated. The Romanowsky-stained cytology specimens were reviewed. When available, Papanicolaou-stained smears were included. The cytologic findings for each of the 3 groups are described, and the most significant findings are photographically illustrated.
Miller RI, Campbell RS.A survey of granulomatous and neoplastic diseases of the skin of horses of tropical north Queensland was carried out during the period 1970-1980. Of 338 horses affected, 46.4% suffered from equine fibrosarcoma (sarcoid), 30.2% from phycomycosis, 7.4% from squamous cell carcinoma, 6.8% from other tumours, 4.7% from cutaneous habronemiasis and 4.4% from exuberant granulation tissue. Most specimens were submitted during the first half of the year after the wet monsoonal season and significantly more diseases originated during the first quarter. There was minor variations with breed, age and sex s...
Bosch G, Klein WR.To determine the usefulness and clinical outcome of a combined procedure of superficial keratectomy and cryosurgery as a treatment for limbal neoplasms in horses. Methods: Retrospective study. Methods: Thirteen horses with 14 limbal tumors. Methods: Medical records of all patients with limbal tumors, referred to the Department of Equine Sciences of Utrecht University between 1995 and 2002, were retrieved. Patient data were analyzed with respect to signalment, tumor surface area and histologic diagnosis. Surgery, performed under general anesthesia, included surgical debulking of the tumor follo...
Fischer AT, Spier S, Carlson GP, Hackett RP.In 6 horses with urinary bladder neoplasms, common clinical findings included a palpable mass in the bladder, anemia, hematuria, and/or proteinuria. Squamous cell carcinoma was found in 4 horses and appears to be the most common bladder tumor in the horse. Single cases of transitional cell carcinoma and fibromatous polyp also were identified. All horses except one were over 10 years of age. In one mare, treatment with 5-fluorouracil intracystically resulted in decreased bleeding from the bladder mass and apparent stabilization of the mass size. The mare ultimately died because of abdominal met...
Cappelli K, Ciucis CG, Mecocci S, Nervo T, Crescio MI, Pepe M, Gialletti R, Pietrucci D, Migone LF, Turco S, Mechelli L, Passamonti F, Drago C....Equine Papillomavirus 2 (EcPV2) is responsible for squamous cell carcinomas (eSCCs) of external genitalia of both male and female horses. However, few studies report the EcPV2 prevalence among healthy horses. Currently, the lack of these data does not permit identifying at-risk populations and, thus, developing screening protocols aimed at the early detection of the infection, as for humans. The aim of our study was to estimate the genoprevalence of EcPV2 in clinically healthy horses in Italy and to evaluate their innate immune response. For this purpose, penile and vulvar swabs of 234 healthy...
Tennant B, Keirn DR, White KK, Bentinck-Smith J, King JM.Six cases of squamous cell carcinoma of the stomach in horses seen at the New York State College of Veterinary Medicine are compared with 15 similar cases reported previously. Clinical signs included anorexia in all cases, emaciation, fever, anaemia and/or palpable abdominal masses in 3, colic in 2 and dysphagia in one case. Haematological studies revealed normochromic, normocytic anaemia in 3 and absolute neutrophilia in 5 cases. Peritoneal fluid analysis was performed in 4 cases and revealed slightly to moderately elevated total protein concentrations in 3 and a markedly elevated number of w...
Elce YA, Orsini JA, Blikslager AT.To assess expression of cyclooxygenase (COX)-1 and -2 in naturally occurring squamous cell carcinomas (SCCs) and the analogous normal tissues in horses. Methods: Tissue samples collected from 3 conjunctival, 2 vulvar, 4 preputial, and 5 penile SCCs during surgical excision in 14 horses and from corresponding body regions (conjunctiva [n = 5 horses], vulva [2], prepuce [3], and penis [3]) in 5 horses euthanized for reasons unrelated to neoplasia. Methods: Tissue samples were snap frozen in liquid nitrogen and stored at -80 degrees C until analysis. Protein was extracted from the frozen tissues,...
Rizk A, Mosbah E, Karrouf G, Abou Alsoud M.Penile and preputial neoplasia in horses occurs infrequently and represents diagnostic and therapeutic challenges. The present study was carried out on a total number of 21 equids (14 stallions and 7 donkeys) suffered from different penile and preputial neoplasia. Diagnosis of neoplasms was based up on history of the case, clinical examination as well as histopathological evaluation. Animals with penile and preputial neoplasms were underwent local excision and partial phallectomy with a slightly modified version of the techniques described by William's. The diagnosed neoplasms were penile and ...
Markel MD, Wheat JD, Jones K.The medical records of 10 horses with invasive neoplasms of the penis, prepuce, and/or superficial inguinal lymph nodes in which treatment involved en bloc resection and penile retroversion were reviewed. All were geldings and ranged in age from 12 to 25 years (mean, 19 years). Evaluation of biopsy specimens obtained before surgery confirmed lymphosarcoma in 1 horse and squamous cell carcinoma in 9 horses. Typical history included swelling, ulceration, and abscessation of the penis and prepuce and large superficial inguinal lymph nodes. Complications after surgery included dehiscence of the ur...
Walker MA, Schumacher J, Schmitz DG, McMullen WC, Ruoff WW, Crabill MR, Hawkins JF, Hogan PM, McClure SR, Vacek JR, Edwards JF, Helman RG, Frelier PF.Three adult horses underwent aggressive treatment of squamous cell carcinoma of the nasal cavity and paranasal sinuses, using course-fractionated cobalt 60 radiotherapy. Squamous cell carcinoma of the nasal cavity and paranasal sinuses is not commonly diagnosed in horses. Historically, horses with this type of neoplasm have not been treated or have undergone some form of surgery. The prognosis for long-term survival or cure has been poor. Long-term results of cobalt 60 radiotherapy were good to excellent and exceeded those usually reported for horses treated surgically. On the basis of these r...
Straticò P, Razzuoli E, Hattab J, Guerri G, Celani G, Palozzo A, Bonanni D, Fruscione F, Varasano V, Petrizzi L, Marruchella G.A 7-year-old Friesian stallion with a history of oesophageal stenosis, weight loss, inappetence, and recurrent hyperthermia was referred for gastroscopy. The stomach mucosa surrounding the oesophageal opening showed a large, necrotic, and ulcerated mass. On post-mortem examination, a very large, cauliflower-like neoplasm was seen, affecting non-glandular gastric mucosa. Nodular lesions were observed, scattered on the omentum, the spleen, and the liver. Microscopic findings allowed the diagnosis of gastric squamous cell carcinoma with abdominal metastasis. Biomolecular investigations demonstrat...
Wilkie DA, Burt JK.Unilateral ocular squamous cell carcinoma in a horse was treated effectively with a combination of repeated radiofrequency hyperthermia and interstitial radiotherapy. These 2 modalities of treatment are synergistic. Interstitial irradiation was achieved, using 198Au implants to deliver a total dose of approximately 5,000 rads/implant over an area of 1 cm2. Radio frequency hyperthermia was repeated 3 times, and radiotherapy was used twice. Treatment resulted in complete regression of the tumor, and ocular complications have not been seen.
Malalana F, Knottenbelt D, McKane S.Ocular lesions in horses, confirmed as squamous cell carcinoma, were treated topically with mitomycin C. Fourteen horses with confirmed ocular squamous cell carcinoma, three of which were affected bilaterally, were included in the study. Eight of the affected eyes were treated topically with mitomycin C alone; in the other nine eyes, the tumours were surgically removed and topical treatment with mitomycin C was then applied. The treatment protocol consisted of 0.2 ml of 0.04 per cent mitomycin C instilled into the conjunctival sac of the affected eye, every six hours, in rounds of seven days o...
Berry CR, O'Brien TR, Pool RR.Squamous cell carcinoma of the hoof wall, with resultant invasion of the right hind distal phalanx, was identified in a 15-year-old Thoroughbred stallion. The clinical features included a chronic grade 2/5 right hind limb lameness and a sessile dorsal hoof wall mass that was not sensitive to palpation. Radiography revealed a well-circumscribed circular lucency within the distal phalanx, beneath the clinically noticed hoof wall mass. These features were considered to be characteristic of a hoof wall keratoma. Surgical intervention was done 10 months later. The histologic diagnosis at the time o...
Rassnick KM, Njaa BL.Squamous-cell carcinoma (SCC) is the second most common tumor in horses, and 40%-50% may occur in ocular and adnexal structures. Cyclooxygenase (COX)-2 is an inducible enzyme responsible for the production of prostaglandins that control cell growth and the development and progression of cancer. Mechanisms responsible for the initial upregulation of COX-2 in neoplasia are unclear; prolonged sunlight exposure and mutations in the p53 gene may be possibilities. Because the etiopathogenesis of ocular SCC in horses may involve ultraviolet sunlight and p53 mutations, the purpose of this study was to...
Smith KM, Scase TJ, Miller JL, Donaldson D, Sansom J.To investigate whether cyclooxygenase-2 (COX-2) is expressed by equine ocular and adnexal squamous cell carcinomas (SCC). Methods: Forty-three samples of histologically confirmed cases of ocular SCC or carcinoma in situ (CIS) from 34 horses presented to the Animal Health Trust between 1992 and 2004 were subjected to a standard, two-layered, indirect immunohistochemical method using a rabbit polyclonal antihuman COX-2 antibody. Ten formalin-fixed, paraffin-embedded tissue samples taken from recognized predilection sites for SCC, from the grossly normal eyes of 10 horses euthanized for reasons u...
Spugnini EP, Bolaffio C, Scacco L, Baldi A.A twenty-year-old female saddle horse was referred for evaluation of a seven month, non-healing erosive lesion of the right hind hoof with proliferation and bleeding of the underlying soft tissues. This lesion had been twice surgically treated as a canker but rapidly recurred. Histological examination of the second excision revealed a well-differentiated squamous cell carcinoma. At presentation, the horse was mildly depressed, lame and partially non-weight-bearing on the right hind leg, which exhibited a 10 x 10 cm erosive and proliferative lesion remodeling the hoof. After completing staging ...
Crausaz M, Launois T, Smith-Fleming K, McCoy AM, Knickelbein KE, Bellone RR.Squamous cell carcinoma (SCC) is the most common cancer affecting the equine eye. A missense variant within the gene damage-specific DNA binding protein 2 (DDB2 c.1013C>T, p.Thr338Met) was previously identified as a causal recessive genetic risk factor for the development of ocular SCC within Haflingers, Belgian Draft horses, and Rocky Mountain Horses, but not in the Appaloosa or Arabian breeds. This study aimed to evaluate three cases of ocular SCC in additional breeds and determine if DNA testing for the DDB2 variant in warmblood horses and Connemara ponies is warranted. Histopathology confi...
Bastianello SS.A survey was carried out on the neoplasms of horses, donkeys and mules which are recorded in the registration files of the Section of Pathology of the Veterinary Research Institute, Onderstepoort, in the Republic of South Africa, over a 40-year period from 1935 to 1974. A total of 378 tumours are recorded, 339 of which were in horses, 32 in mules and 7 in donkeys. Sarcoids (38%), squamous cell carcinomas (23,5%), fibromas (8,2%), melanomas (8,0%), papillomas (4,5%), fibrosarcomas (3,4%) and lymphosarcomas (3,0%) accounted for 88,6% of the total. Of the 58 sarcoids for which the site or origin ...
McInnis CL, Giuliano EA, Johnson PJ, Turk JR.To evaluate expression of cyclooxygenase (COX)-1 and COX-2 in the cornea, eyelid, and third eyelid of healthy horses and those affected with squamous cell carcinoma (SCC) by use of immunohistochemical techniques. Methods: 15 horses with SCC involving ocular tissues and 5 unaffected control horses. Methods: SCC-affected tissues were obtained from the cornea (n = 5 horses), eyelid (5), and third eyelid (5). Site-matched control tissues were obtained from 5 horses unaffected with SCC. Tissue sections of affected and control cornea, eyelid, and third eyelid were stained immunohistochemically for C...
Schellenbacher C, Shafti-Keramat S, Huber B, Fink D, Brandt S, Kirnbauer R.The consistent and specific presence of Equus caballus papillomavirus type 2 (EcPV2) DNA and mRNA in equine genital squamous cell carcinoma (gSCC) is suggestive of an etiological role in tumor development. To further validate this concept, EcPV2-neutralizing serum antibody titers were determined by an EcPV2 pseudovirion (PsV) neutralization assay. Furthermore, an EcPV2 L1 virus-like particle (VLP)-based vaccine was generated and its prophylactic efficacy evaluated in vivo. All 6/6 gSCC-affected, but only 3/20 tumor-free age-matched animals revealed EcPV2-neutralizing serum antibody titers by P...
Payne RJ, Lean MS, Greet TR.Between October 2000 and January 2007, 24 horses were presented with suspected squamous cell carcinoma (SCC) of the third eyelid. The hospital's medical records were analysed retrospectively to gain data about the cases, and telephone follow-up was obtained from the owners and referring veterinary surgeons. The resected third eyelid was submitted for histological examination in 21 cases; in the other three cases the tissue was not submitted at the owners' request, for economic reasons. SCC was confirmed in 16 of these 21 cases, three cases were diagnosed histologically as lymphoid hyperplasia,...
Grier RL, Brewer WG, Paul SR, Theilen GH.Forty-five ocular squamous cell carcinomas (SCC) in 17 cattle and 8 horses were treated by radiofrequency hyperthermia, resulting in 80% complete regression and 16% partial regression. Tumors were histologically diagnosed as SCC; 50% of the tumors were recurrent, having been treated previously by surgery, cryosurgery, radiation, or immunotherapy. After hyperthermic treatment, most animals were available for tumor measurement at 4 to 6 weeks and at 8 to 16 weeks, with a final observation period of 2 to 10 months for all. Complete regression occurred in 8 of 12 tumors given a second hyperthermic...
Munday JS, Knight CG, Luff JA.Papillomaviruses (PVs) are well recognized to cause pre-neoplastic and neoplastic diseases in humans. Similarly, there is increasing evidence that PVs play a significant role in the development of pre-neoplastic and neoplastic diseases of the haired skin of dogs and cats, and the mucosa of horses. As the mechanisms by which PVs cause neoplasia are well studied in humans, it is valuable to compare the PV-induced neoplasms of humans with similar PV-associated neoplasms in the companion animal species. In the second part of this comparative review, the pre-neoplastic and neoplastic diseases thoug...
Strohmayer C, Klang A, Kummer S, Walter I, Jindra C, Weissenbacher-Lang C, Redmer T, Kneissl S, Brandt S.Squamous cell carcinoma of the head and neck (HNSCC) is a common malignant tumor in humans and animals. In humans, papillomavirus (PV)-induced HNSCCs have a better prognosis than papillomavirus-unrelated HNSCCs. The ability of tumor cells to switch from epithelial to mesenchymal, endothelial, or therapy-resistant stem-cell-like phenotypes promotes disease progression and metastasis. In equine HNSCC, PV-association and tumor cell phenotype switching are poorly understood. We screened 49 equine HNSCCs for equine PV (EcPV) type 2, 3 and 5 infection. Subsequently, PV-positive versus -negative lesi...
