Tumours In Horses Research Articles

Equine Basal Cell Tumors: 6 Cases (1985–1999)

Basal cell tumors are rare benign tumors in horses. Over a 15‐year period, 6 horses were diagnosed with basal cell tumors. The tumors were well‐circumscribed, freely moveable, firm, raised papules, nodules, or masses that ranged from 0.6 to 5 cm in diameter. Five of the 6 tumors were ulcerated. Based on gross appearance, the tumors were diagnosed as sarcoids, and 1 was diagnosed as a melanoma. The range of age of affected horses was 6–26 years. The tumors were identified clinically 1 week to 3 years before excision. In 4 horses for which information was available, complete surgical excision was curative with no recurrence 4 months to 2 years after removal.

Proliferation, DNA ploidy, p53 overexpression and nuclear DNA fragmentation in six equine melanocytic tumours.

Melanocytic tumours are a well-known clinical and pathological entity in horses, but further phenotypic characterization of these tumours is lacking. Six melanocytic tumours from five horses (two metastatic and four benign) were examined by Ki67, PCNA and p53 immunostaining, DNA nick end labelling (Tunel) and Feulgen staining. The stainings were evaluated using quantitative image analysis. The resulting parameters of growth fraction (Ki67), S-phase index (PCNA), p53 index, apoptotic index, DNA index, nuclear diameter, ploidy balance, proliferation index (Feulgen) and hyperploidy were analysed. The metastatic melanomas showed overexpression of p53 in a large portion of the cells. Apoptosis was also found in the metastatic melanomas. No differences were found in growth fraction, S-phase index (PCNA) nor in DNA configuration between the metastatic and the benign tumours. No immunohistochemical evidence of mutant p53 could be found in the tumours. In conclusion, melanocytic tumours in horses seem to have different phenotypic characteristics in comparison with melanocytic tumours in dogs, cats and humans, especially with respect to proliferative activity of the benign tumours. Therefore, markers put forward in these other species for predicting the clinical behaviour of the melanomas seem to be of no value in the horse. Moreover, quantitative DNA changes or p53 mutations do not seem to be involved in tumourogenesis in these cases.

Comparison of perioperative versus postoperative intratumoral administration of cisplatin for treatment of cutaneous sarcoids and squamous cell carcinomas in horses

Objective To determine the benefits of reducing the interval between surgical cytoreduction and intratumoral administration of cisplatin. Design Randomized clinical study. Animals 70 horses with 89 incompletely resected T2- and T3-stage sarcoids (n = 64) and squamous cell carcinomas (25). Procedure Horses were given 4 intratumoral treatments of cisplatin at 2-week intervals. The first treatment was given at the time of, or immediately after, surgical resection for horses treated in accordance with the perioperative protocol (group 1). Horses in group 2 were treated with cisplatin after the skin healed following surgical resection in accordance with the postoperative protocol. Results A difference was not found in duration of overall local tumor control between the 2 groups. Patterns of treatment failures and interval to failure differed between the 2 groups. Length of the surgical scar was the only factor that affected prognosis; an increase in length was associated with a poorer prognosis. A detrimental effect of postoperative treatment was only found in tumors with a high tumor proliferative fraction. Local reactions were similar for the 2 treatment groups, and chronic reactions were not observed. Conclusions and Clinical Relevance Intratumoral administration of cisplatin is beneficial for treatment of cutaneous tumors in horses. Tumor repopulation during the interval between surgery and intratumoral administration of cisplatin decreases treatment efficacy. These results provide evidence of rapid tumor repopulation following surgical resection without a lag period for tumors with a high proliferation index. When tumor proliferation index is not known, it may be prudent to use the perioperative protocol. (J Am Vet Med Assoc 1999;215:1655–1660)

Simultaneous Occurrence of Multiple Neoplasms and Hyperplasias in the Adrenal and Thyroid Gland of the Horse Resembling Multiple Endocrine Neoplasia Syndrome: Case Report and Retrospective Identification of Additional Cases

Neoplastic and hyperplastic disorders that affect multiple endocrine tissues in a single individual are well described in humans but less so in domestic animals. Multiple endocrine neoplasia (MEN) in humans is a genetically determined syndrome characterized by the appearance of benign or malignant proliferations within two or more endocrine glands. The primary endocrine tumors that are characteristic of MEN arise from cells that share the capacity for amine precursor uptake and decarboxylation. Here we describe the case of a 22-year-old Thoroughbred mare that died during an unattended parturition and subsequently was presented for necropsy at the University of California, Davis, Veterinary Medical Teaching Hospital. A C-cell (medullary) thyroid adenoma, pheochromocytoma, and multicentric bilateral nodular hyperplasia of the adrenal medulla were present, findings that are remarkably similar to those of human MEN syndrome. Mortality during pregnancy in women with undiagnosed pheochromocytoma is high (approximately 50%), typically because of hypertension and/or hemorrhage associated with catecholamine release from the tumor. Similarly, the mare in this report died of hemorrhage subsequent to parturition. A retrospective evaluation of endocrine tumors in horses that underwent necropsy at the Veterinary Medical Teaching Hospital from 1987 to 1997 was undertaken to identify additional possible cases of MEN in horses. Data from this retrospective evaluation suggest that coexistence of hyperplasias and neoplasias of the thyroid and adrenal glands, similar to MEN syndrome of humans, also occurs with some frequency in the horse.

Factors associated with the risk of developing sarcoid tumours in horses.

A retrospective case-control study was conducted to identify risk factors in horses associated with the development of the common skin tumours known as sarcoids. The study involved 503 sarcoid cases diagnosed (January 1980-December 1989) at New York State College of Veterinary Medicine and a similar number of controls (non-sarcoid cases). Data on age, breed and sex of cases and controls were obtained from computerised records. Multiple logistic regression analysis was used to identify risk factors. Separate data were obtained for the same 10-year period from the Veterinary Medical Data Program to determine the proportional morbidity rate at different veterinary colleges in North America. Appaloosa, Arabian and Quarter horses were at a higher risk of developing sarcoid tumours than were Thoroughbred horses. Standardbred horses had a lower risk of developing sarcoids. Geldings were at a higher risk of developing sarcoids in comparison with stallions. There was no significant difference in the risk of developing sarcoids between stallions and mares. The risk of developing sarcoid increased with age up to 15 years and then declined. The proportional morbidity rate of sarcoids among the veterinary colleges ranged between 0 and 14 per 1,000 cases, with an average of 6 per 1,000.

Malignant mast cell tumours in horses

Malignant mast cell tumours in horses

Correspondence: Tumours in horses encountered in an abattoir survey.

Correspondence: Tumours in horses encountered in an abattoir survey.

WORM TUMOURS IN HORSES.

WORM TUMOURS IN HORSES.

Primary Spontaneous Tumors of the Ovary Tn Mice: Studies on the Incidence and Inheritability of Spontaneous Tumors in Mice: Fourteenth Communication

Throughout the animal kingdom the solid ovarian tumors seem to be infrequent, as they also are, relatively, among human tumors. Cystic tumors are described occasionally, but apparently less frequently in the lower animals than in man. Even among dogs, with their high incidence of tumor growth, ovarian tumors are rare according to the evidence furnished by literature dealing with canine neoplasms.1 In Sticker's (2) compilation of tumors in domestic animals, of 766 tumors in dogs but 3 were in the ovary. As to other animals of Sticker's series, in 509 cases of tumors in horses, 4 were in the ovary; of 110 in cattle, 6 were ovarian; there was 1 ovarian tumor among 23 tumors in cats, and none at all among sheep, goats, and swine. Kimura (3) has reported 142 cases of tumors in horses, among which were no ovarian tumors, although there were 49 in the testicle. Other evidence supports the figures of Sticker in indicating that cows have ovarian tumors more often than other species. Trotter (4) reported 305 bovine tumors observed in the Glasgow slaughter house, of which 5 were in the ovary (4 carcinomas and 1 sarcoma). These were all large tabulated solid tumors, and no metastases were observed in any. Leo Loeb (5) has described a tumor arising in the ovary of a six-months-old calf, composed chiefly of cells resembling luteum tissue. Among the numerous instances of tumors in wild rats reported by McCoy (6), Woolley and Wherry (7), and Beatti (8) there is no case of ovarian growth; nor have we found reports of any cases occurring in domesticated rats.2 Wolff (9) mentions 2 cases of ovarian tumors in cats: One a primary carcinoma in the ovary of a thirteen-year old cat with metastasis in the liver, reported by Kitt; the other a sarcoma of the ovary and pelvis reported by Stroud. Wild animals are also unlikely to have ovarian tumors. Fox (10), in his extensive studies of tumors in wild animals, has described no cases whatever of ovarian tumors among the mammalia. Only in birds do ovarian tumors seem to be relatively frequent. Burger (11) found, among 852 fowls autopsied at the Leipzig veterinary institute, 12 tumors, of which 7 were in the ovary, 4 being sarcomas and 3 carcinomas; 2 of the sarcomas and 2 of the carcinomas had produced metastases. In their review of the literature on tumors in birds, Joest and Ernesti (12) found 112 cases reported and added 50 more. Of these 162 cases, 21 were primary carcinoma of the ovary, commonly with extensive peritoneal and visceral metastasis. There was also one case of ovarian sarcoma.