Service in Vietnam and risk of testicular cancer.
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Biomedical subjects
Publications and source records attributed to H M Hayes.
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A hospital-based case-control study of companion dogs examined the risk of developing canine malignant lymphoma associated with the use of chemicals in and about the home. Information from a self-administered owner questionnaire and/or a telephone interview of about 491 cases, 466 nontumor controls, and 479 tumor controls indicated that owners in households with dogs that developed malignant lymphoma applied 2,4-dichlorophenoxyacetic acid (2,4-D) herbicides to their lawn and/or employed commercial lawn care companies to treat their yard significantly more frequently than control owners (odds ratio = 1.3). In addition, the risk of canine malignant lymphoma rose to a twofold excess with four or more yearly owner applications of 2,4-D. The findings in this study are consistent with occupational studies in humans, which have reported modest associations between agricultural exposure to 2,4-D and increased risk of non-Hodgkin's lymphoma, the histology and epidemiology of which are similar to those of canine malignant lymphoma. The present study suggests that human health implications of 2,4-D exposure in the home environment should receive further investigation.
During the Vietnam War, US military working dogs served with their companion dog handlers in close proximity, sharing common exposures to war-related activity, many zoonotic infectious agents, chemical pesticides, phenoxy herbicides, and extensive use of therapeutic drugs. To gain insight into the effects of the Vietnam experience, we investigated the occurrence of neoplasms in military working dogs based on standard necropsy examination by the Armed Forces Institute of Pathology. We observed that these dogs experienced significant elevated risks for testicular seminoma and, independently, testicular dysfunction. Experimental evidence shows testicular dysfunction and impaired spermatogenesis in laboratory animals exposed to phenoxy herbicides, dioxin, or tetracycline, and antibiotic used extensively in military working dogs in Vietnam. Because an unexplained significant decrease in sperm quality in Vietnam veterans has been observed by the Centers for Disease Control, further research is warranted if we are to clarify military service in Vietnam as a risk factor for testicular dysfunction. The testis should be made a priority site in the study of Vietnam experience-related cancers.
Neoplasms of the perianal gland are common in the dog, particularly the male. Adenomas of the gland develop about 4.5 times more often than do carcinomas of the gland. The adenoma is hormone dependent; thus, castration without excision of the tumor has been successful in promoting regression without recurrence. Microscopic examination of the testes from dogs with perianal gland neoplasms has revealed 1 in 10 with tubular atrophy and 1 in 3 with testicular neoplasia. Interstitial cell tumors have been seen more often than other cell types of testis tumors.
In a retrospective study of hydrocephalus (of congenital origin) diagnosed in 564 dogs, 11 breeds (including 8 "toy" breeds) were identified as being a significantly high risk. An inverse relationship between risk and body size was detected. The smaller the dam at maturity, either in height at the shoulder or body weight, the greater the risk of hydrocephalus in the offspring.
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Twenty-seven cases of patent ductus arteriosus (PDA) in the dog, which were confirmed by cardiac catheterization, surgical exploration, or at necropsy, were reviewed. A machinery murmur, electrocardiographic evidence of left ventricular enlargement, and radiographic evidence of cardiomegaly with an aortic and a pulmonary artery dilatation were consistent features. Surgical repair was successful in 65% of the dogs. The postoperative radiographic and electrocardiographic changes are described. A concomitant congenital defect was present in 2 dogs. The epidemiologic features of 532 dogs identified as having PDA and submitted to the National Cancer Institute's Veterinary Medical Data Program were reviewed. Miniature and Toy Poodles, Pomeranians, and Shetland Sheepdogs were identified as being at high risk for PDA. An excess of females over males was noticed.
Arsenic poisoning is one of the more important causes of heavy metal poisoning in domestic animals. Two species--dogs and cattle--are intoxicated more frequently than other animals; yet sporadic instances of poisoning have been observed in cats, horses, and pigs. Cases observed by veterinary clinicians are either peracute, acute, or chronic intoxications. Frequently the initial and only indication that a severe problem exists with peracute poisoning in a cattle herd is dead animals. Chronic intoxications are also observed in cattle. Acute intoxication is the most common form of arsenic poisoning observed and documented in the dog. Also intoxicated dogs were younger, i.e., 2-6 months of age. Arsenic is a severe alimentary tract irritant in domestic animals, and treatment in most instances consists mainly of symptomatic and supportive treatment. The source of intoxication, when it can be determined, is usually dips, sprays, powders, or vegetation contaminated by pesticides containing arsenic.
The epidemiological features of 472 dogs with microscopically confirmed neoplasms of the perianal gland are described. These general characteristics suggest etiological factors similar to those responsible for hormone-related neoplasms occurring in human beings. Perianal gland tumors appear to be androgen dependent. Male dogs show a 5.6-fold-increased risk compared with females; endogenous estrogens offer protection and the use of estrogenic hormones is conventional therapy for the benign lesion. Both sexes of the cocker spaniel breed show excessively high risk, suggesting that this dog family may be a model for genetic studies that could be relevant to familial aggregations of hormone-related tumors in men and women. Adrenocortical hormones may play a role in the development of the tumor in female dogs. Research into alterations of the biochemical pathways of steroidogenesis in affected female dogs may provide clues to similar conditions in humans.
A retrospective study of medical records from 13 veterinary university hospitals and clinics yielded 73 cases of confirmed primary neoplasms of the kidney and renal pelvis. Analysis of the 34 cases of renal carcinoma revealed no evidence of familial (breed) predisposition, but an excess risk was identified in males, especially during middle life. The morphological and epidemiological features of canine renal carcinoma are similar to those of renal carcinoma in humans. The dog may be a suitable model for further research into the causes of this cancer.
Histologically confirmed testicular tumors were diagnosed in 410 dogs from 12 North American veterinary university hospitals and clinics. Three tumor-cell types, Sertoli cell tumor, interstitial cell tumor and seminoma, were about equally represented. Several breeds were identified with high risk for different testicular tumor-cell types. Cytogenetic and immunogenetic studies of these dog families could offer leads applicable to familial testicular cancer in man. The multiplicity of breeds within the series suggests that, as in man, other factors, in addition to hereditary, play a role in etiology. Cryptorchid dogs appear to have a 13.6 times higher risk of testicular tumor than normal dogs. Additionally, male dogs with an inguinal hernia have an increased risk (4.7) of testis tumors. There were no detectable excesses of other urogenital anomalies or urogenital tumors among the series. The Shetland Sheepdog is suggested as an appropriate model for research into the mechanisms responsible for testicular maldescent and tumorigenesis.
A retrospective study of medical records from 13 veterinary university hospital clinics yielded 114 dogs with microscopically confirmed primary malignancy of the bladder. When matched to controls, there was no increased frequency to suggest an association of urogenital tumors or anomalies with neoplasms of the bladder. The majority of tumors seen in this study were transitional cell carcinomas. Four breeds were identified with excessive risk for bladder cancer and may serve as models for further research into genetic determinants, such as abnormal tryptophan metabolism. The epidemiologic features of canine bladder cancer were compared with the disease in man. An excess among female dogs may be the result of less frequent urination as compared to male dogs. Assuming an etiology from urine-borne carcinogens applies to spontaneously occurring bladder cancer in dogs, then monitoring the frequency of occurrence of canine bladder cancer may provide an early warning of emerging environmental hazards to man.
From 11 North American veterinary university hospitals and clinics, 248 animals were a confirmed diagnosis of nervous-tissue tumor were identified; 7 tumors were found in cattle, 28 in horses, 14 in cats, 199 in dogs, and none in other species. Tumors were divided for analysis into three categories-glial, meningeal, and peripheral nerve. In cattle and horses, all tumors involved peripheral nerves, the risk of which, in horses, reached a plateau at 4-6 years of age and remained constant thereafter. In cats, the tumors were equally distributed among the three tumor categories whereas, in dogs, twice as many glial tumors as meningeal and peripheral nerve tumors were found. The risk for glial tumors in dogs reached a peak at 10-14 years of age, for meningeal at 7-9 years, and for peripheral nerve at 2-3 and 7-9 years. Three canine breeds-English bulldog, boxer, and Boston terrier-had an excessive rish of glial tumors. Except for an excess of skin tumors in dogs with peripheral nerve tumors, there was no unusual occurrence with second primary neoplasms for any species. There was no detectable predisposition by sex for any of the categories of nervous-tissue tumors among any of the four species. The role of genetic abnormalities associated with nervous-tissue tumors and other etiologic factors (e.g., chronic hypoxia) may be clarified by further studies involving canine breeds of "bulldog" ancestry.
In a study of 1266 dogs with cryptorchism from a large clinic/hospital series 8 breeds were found to be at excess risk of the defect and 3 breeds at significantly low risk. Review of the medical histories revealed that hip dysplasia, patellar dislocation, defects of the penis and prepuce, and umbilical hernia were excessively associated with cryptorchism. Testicular tumors were diagnosed 10.9 times more commonly among cryptorchid dogs. The epidemiologic features of canine cryptorchism were compared with those in man. Cryptorchid dogs could be used as models for etiologic research.
A retrospective study of medical records from twelve veterinary university hospitals-clinics yielded 144 dogs with a confirmed diagnosis of a thyroid neoplasm (25 adenomas and 119 carcinomas). Forty-five of these dogs had additional primary neoplasms. As in man, associated tumors suggested the inherited multiple endocrine adenomatosis, type 1, and a possible syndrome of thyroid and chemoreceptor lesions. Although the female preponderance of human thyroid cancer was not seen in dogs, females showed a much sharper increase in risk with advancing age than did males. Three breeds (beagle, boxer, and golden retriever) had a significantly greater risk for thyroid carcinoma than did all dogs combined, whereas miniature and toy poodles had a low risk. The function of thyroiditis in the origin of thyroid cancer, as suggested by reports of thyroid carcinoma in people with Hashimoto's disease, may be clarified by follow-up studies of beagles which are prone to Hashimoto-type thyroiditis.
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