Topic:Cancer
Cancer in horses encompasses a range of neoplastic diseases that affect various tissues and organs in equine species. These conditions involve the uncontrolled growth of abnormal cells, which can form tumors and potentially spread to other parts of the body. Common types of cancer in horses include sarcoids, squamous cell carcinoma, and melanoma, each with distinct characteristics and clinical presentations. Diagnosis often involves a combination of physical examination, imaging techniques, and histopathological analysis. Treatment options vary based on the type and stage of cancer and may include surgical intervention, chemotherapy, and radiation therapy. This page compiles peer-reviewed research studies and scholarly articles that explore the epidemiology, pathophysiology, diagnostic methods, and treatment strategies for cancer in horses.
EcPV2 DNA in equine squamous cell carcinomas and normal genital and ocular mucosa. 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...
Pleuropulmonary blastoma in an equine fetus. Pleuropulmonary blastoma (PPB) is a rare biphasic tumor of children formed by mixed epithelial-and-mesenchymal elements. In this article, the authors report a pulmonary mass in an equine fetus with characteristics of PPB. A soft multicystic broad-based pleural mass was identified in the right caudal lung lobe. The mass comprised solid areas of loose mesenchyme, fenestrated by small ducts or large cystic areas lined by cuboidal epithelium. Mesenchymal elements had moderate anisocytosis, anisokaryosis, and cellular pleomorphism and were immunoreactive for vimentin. Epithelial cells lining ducts ...
Redox cycling of catechol estrogens generating apurinic/apyrimidinic sites and 8-oxo-deoxyguanosine via reactive oxygen species differentiates equine and human estrogens. Metabolic activation of estrogens to catechols and further oxidation to highly reactive o-quinones generates DNA damage including apurinic/apyrimidinic (AP) sites. 4-Hydroxyequilenin (4-OHEN) is the major catechol metabolite of equine estrogens present in estrogen replacement formulations, known to cause DNA strand breaks, oxidized bases, and stable and depurinating adducts. However, the direct formation of AP sites by 4-OHEN has not been characterized. In the present study, the induction of AP sites in vitro by 4-OHEN and the endogenous catechol estrogen metabolite, 4-hydroxyestrone (4-OHE), ...
Bovine papillomavirus DNA can be detected in keratinocytes of equine sarcoid tumors. Bovine papillomavirus (BPV)-1 and -2 is linked to equine sarcoids, a commonly observed skin tumor in horses that is of considerable veterinary importance. Previous studies using in situ hybridization have detected BPV DNA only in fibroblasts and not in keratinocytes of sarcoids. In contrast, normal equine skin latently infected with BPV shows a dysplastic epithelium without dermal changes, similar to lesions induced by other papillomavirus types infecting the epithelium. The first goal of our study was to describe the epidermal and dermal characteristics of several stages in sarcoid developmen...
Tissue and cell tropism of African horse sickness virus demonstrated by immunoperoxidase labeling in natural and experimental infection in horses in South Africa. Tissues from 196 experimental and confirmed natural cases of African horse sickness (all 9 serotypes) were examined with a standardized and validated immunohistochemical assay for detection of the causative virus. The study confirmed that heart and lung are the main target tissues for African horse sickness virus (across all serotypes), followed closely by spleen. It also indicated that microvascular endothelial cells and monocyte-macrophages are the main target cells for virus replication. The importance of monocytes as target cells was emphasized, with relatively few tissue macrophages conta...
Use of Ir192 interstitial brachytherapy for an equine malignant dermal schwannoma. A 10-year-old Hanoverian mare was evaluated for a right buccal swelling that recurred 3 months following surgical resection. Ultrasonographic examination showed a broadly pedunculated subcutaneous mass at the level of 106-109 and 406-409 cheek teeth associated with an erosive mucosal lesion on the inside of the cheek. Histological examination of a biopsy specimen revealed a well-demarcated, malignant, dermal schwannoma. Following subcutaneous placement of platinum coated Ir192 wires under general anaesthesia, low-dose radiation of 5 gray per day was delivered for 14 days. Short-term complicati...
Occult metastatic intestinal adenocarcinoma resulting in pathological fracture of the proximal humerus. Intestinal adenocarcinomas are rare but have been described in the literature. The present case is unusual in both its clinical presentation and in the distribution of metastatic lesions. The sequestrum formation and pathological fracture present are most commonly associated with osteomyelitis in horses and the details of the case highlight the need for differential diagnosis in these particular circumstances and of which clinicians should be aware.
Media attention and public perceptions of cancer and eastern equine encephalitis. Previous research has found that members of the public have a skewed sense of health risk. The purpose of this research was to investigate how mass media use influences perceptions of threat from cancer and eastern equine encephalitis (EEE). Investigators performed a media content analysis of 253 health-related articles from 11 Massachusetts newspapers, then used logistic regression to analyze responses to a health communication survey of 613 Massachusetts adults. A greater proportion of cancer articles compared to those about EEE mentioned progress in combating the disease (61.0% vs. 16.2%, P...
Equine primary liver tumors: a case series and review of the literature. Hepatoblastoma (HB) is an uncommon pediatric liver tumor in humans and horses. In humans, HB is most frequently diagnosed in fetuses, neonates, and young children, whereas hepatocellular carcinoma (HCC) affects juvenile and adult humans. Hepatoblastoma in the horse is rare, with only 9 reported cases. Affected horses ranged in age from late-term aborted fetuses to 3 years. The current study describes 3 new cases of primary liver tumors in horses and reviews findings in relation to other reports on this condition. Tumors classified as HB were identified in a male Standardbred aborted fetus and ...
Radiation therapy communication: nasal passage and paranasal sinus lymphoma in a pony. An aged pony with extensive paranasal sinus and nasal passage B-cell lymphoma was treated with palliative radiation therapy. Sixteen gray were administered in two fractions, 7 days apart. A lateral field was used for the first fraction and a dorsal field for the second. Because of tumor being present in the left frontal sinus, gross tumor was knowingly excluded from the treated volume in the lateral field. The tumor regressed within 2 months and the pony remained free of clinical disease for 2.5 years. Acute, temporary blindness developed shortly after the second radiation fraction, but a dire...
Gene-based vaccines: Recent developments. Gene-based vaccines are under development for a broad variety of applications, ranging from vaccines to immunotherapies for infectious diseases, cancer, autoimmune diseases and allergy. In addition, following the licensing of DNA vaccines for use in fish and horses, and DNA immunotherapy for the treatment of cancer in dogs, several veterinary uses of vaccines have been demonstrated for species ranging from fish and shrimp to cattle and horses. A variety of publications describing preclinical and clinical studies of the technologies used to increase the potency of gene-based vaccines, and resea...
Hematopoietic neoplasias in horses: myeloproliferative and lymphoproliferative disorders. Leukemia, i.e., the neoplasia of one or more cell lines of the bone marrow, although less common than in other species, it is also reported in horses. Leukemia can be classified according to the affected cells (myeloproliferative or lymphoproliferative disorders), evolution of clinical signs (acute or chronic) and the presence or lack of abnormal cells in peripheral blood (leukemic, subleukemic and aleukemic leukemia). The main myeloproliferative disorders in horses are malignant histiocytosis and myeloid leukemia, the latter being classified as monocytic and myelomonocytic, granulocytic, prim...
Third eyelid resection as a treatment for suspected squamous cell carcinoma in 24 horses. 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,...
A grade IV glioblastoma with an oligodendroglial component (GBM-O) in a horse. A 4-year-old Dutch warmblood mare was presented with a 10-month history of ataxia and proprioceptive deficits. Computed tomography defined a large, non-contrast enhancing mass in the left cerebral hemisphere. Necropsy examination revealed a tumour that effaced much of the piriform and temporal lobes. Microscopically the lesion was classified as a grade IV glioblastoma with an oligodendroglial component (GBM-O). The tumour was composed of highly pleomorphic cells organized in different patterns within a fibrillary stroma. There were multiple foci of necrosis. At the periphery of the tumour neop...
Equine sarcoid fibroblasts over-express matrix metalloproteinases and are invasive. Papillomaviruses are DNA viruses that cause tumours of the skin in humans and animals. The natural host of bovine papillomavirus is cattle, but also equids, resulting in tumours termed sarcoids. Matrix metalloproteinase 1 (MMP-1) expression is up-regulated in sarcoid fibroblasts and tumours. We extended our observation to other MMPs and determined whether MMPs induced invasion of sarcoid fibroblasts. Collagenase (MMP-1) and Gelatinase (MMP-2, MMP-9) were over-expressed in sarcoid fibroblasts and tumours. The fibroblasts were invasive in a 3D/matrigel invasion assay system. Inhibition of MMP by...
Radiation therapy communication: equine hemangioma. A 13-month-old Standardbred Colt had a recurrent hemangioma at the level of the coronary band. Multiple excisions had led to a nonhealing skin and hoof defect. Using 14 MV electrons, a total dose of 36 Gy was administered, given as six fractions of 6 Gy twice a week. Wound healing by second intention was achieved over the next 4 months and the colt began race training 6 months after the end of therapy. Twenty months later the colt is sound and there is no evidence of tumor recurrence.
Small interfering RNA targeting bovine papillomavirus type 1 E2 induces apoptosis in equine sarcoid transformed fibroblasts. Equine sarcoids are skin tumours of horses caused by infection with BPV-1 or 2. Maintenance and replication of the viral genome depend upon the viral proteins E1 and E2. We examined the effects of an E2 specific siRNA on E2 and E1 viral gene expression, viral load and cell growth in BPV-1 transformed sarcoid-derived cells. Transfection with E2-siRNA caused a reduction in E2 and E1 mRNA expression as well as viral load, growth inhibition and decreased anchorage-independent growth. siRNA treated cells showed significantly higher apoptosis rates than control cells. Thus sequence specific targetin...
A retrospective analysis of renal carcinoma in the horse. Renal carcinoma is a rare tumor of horses. Objective: Presenting complaints and clinical signs of this disease are vague and early diagnosis increases survival time. Methods: Data were collected from the medical records of 4 horses presented to Washington State University as well as the 23 previously published case reports of horses with renal carcinoma. Methods: Retrospective study. Results: Renal carcinoma affects horses of all ages with most cases observed in geldings and Thoroughbreds. The most common presenting complaints are nonspecific and usually do not occur until late in the course o...
A biphasic malignant mesothelioma of the peritoneum and pleura in a horse. This report describes the macroscopic, histologic, immunohistologic and ultrastructural characteristics ofa biphasic malignant mesothelioma in the peritoneal and pleural cavity of a 13-year-old Icelandic pony mare, which exhibited recurrent ascites clinically. Immunohistology was performed employing multiple monoclonal antibodies against cytokeratins (CK) and vimentin. The ultrastructural examination included the quantitative evaluation of the length to diameter ratio of the microvilli. Post mortem examination revealed a severe ascites and hydrothorax. The serosal surfaces of the peritoneum an...
Adipokines: a review of biological and analytical principles and an update in dogs, cats, and horses. In addition to its role as an energy storage depot, adipose tissue is now recognized as a complex endocrine organ. Adipose tissue releases a variety of factors, termed adipokines, that regulate energy metabolism, cardiovascular function, reproductive status, and immune function. Some of the better-studied adipokines include leptin, adiponectin, and components of the renin-angiotensin system such as angiotensinogen. The function of more recently discovered adipokines such as resistin are under intense scrutiny. Abnormal production or regulation of adipokines occurs in obese individuals and is i...
Equine skin tumours in 20 horses resembling three variants of human melanocytic naevi. Melanocytic tumours are important in horses, especially grey horses. Intradermal common melanocytic naevi, cellular blue naevi and combined cellular blue naevi are subgroups of human melanocytic tumours, which have not been reported in horses. In this study, we describe 20 horses with skin tumours similar to these naevi of humans. These tumours represented individual skin masses in male and female horses of different breeds. Tumours resembling human intradermal common melanocytic naevi were noted in 12 horses aged between 2 and 17 years. Seven horses aged between 4 and 15 years developed cutan...
Activated platelet-derived growth factor beta receptor expression, PI3K-AKT pathway molecular analysis, and transforming signals in equine sarcoids. The equine sarcoid is the most common dermatologic neoplasm reported in horses. Bovine papillomavirus (BPV) types 1 and 2 are associated with sarcoids, in which the expression of the major transforming oncoprotein (E5) is often recorded. The transformation activity of the virus is due to the binding of the E5 to the platelet-derived growth factor beta receptor (PDGFbeta-r). In the present study, we show by Western blot in 4 sarcoid samples and 3 normal equine skin samples that the PDGFbeta-r is more phosphorylated in sarcoid tissue than in normal skin (P < .001). Furthermore, the physical i...
Photodynamic therapy for the treatment of periocular squamous cell carcinoma in horses: a pilot study. 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 ...
Epibulbar melanoma in a foal. A case of epibulbar melanoma in a 6-month-old, gelded, chestnut Hanoverian foal is reported. The location and clinical appearance upon initial presentation led to the tentative diagnosis of staphyloma or a congenital mass of unknown origin. An attempt was made to surgically excise the mass under general anesthesia, but due to its infiltrative nature and intraoperative appearance, most, but not all was removed without compromising the integrity of the globe. Histopathological evaluation revealed a multinodular to packeted, poorly demarcated, unencapsulated, infiltrative exophytic melanocytic ne...
Expression of cyclooxygenase-2 by equine ocular and adnexal squamous cell carcinomas. 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...
Isolation, establishment, and characterization of ex vivo equine melanoma cell cultures. Gray horses spontaneously develop metastatic melanomas that resemble human disease, and this is often accompanied with metastasis to other organs. Unlike in other species, the establishment of primary equine melanoma cultures that could be used to develop new therapeutic approaches has remained a major challenge. The purpose of the study was to develop a protocol for routine isolation and cultivation of primary equine melanocytes. Melanoma tissues were excised from 13 horses under local anesthesia, mainly from the perianal area. The melanoma cells were isolated from the melanoma tissue by seri...
Cyclooxygenase-2 expression in equine tumors. 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...