Understanding Testicular Tumors Or Cancers In Dogs
Testicular tumors account for 90% of all cancers originating from the male reproductive system. Testicular tumors mostly develop from three cell lineages although testicular cancers may also arise from other cell types including hemangiomas, granulosa cell tumors, teratomas, sarcomas, embryonal carcinomas, gonadoblastomas, lymphomas, rete testis and mucinous adenocarcinomas.
3 Most Common Testicular Tumors In Dogs
Testicular tumors are one of the most common tumors in non-neutered dogs. These tumors appear in three distinct types of cell clusters within the testicle:
- Leydig – Part of the anatomy that secretes the testosterone hormone
- Sertoli – Responsible for developing sperm cells through the process of spermatogenesis
- Seminomas – The innermost layer of the testicle that insulates and protects the organ
These tumors occur at a proximal interval of each other and most of the testicular cancers consist these tumors as a whole. Around 40% of dogs have more than 1 primary testicular tumor. Primary tumors rarely metastasize. However, the metastatic sites may include regional draining lymph nodes, liver, pulmonary parenchyma, kidneys, spleen, adrenals, pancreas, skin, eyes and central nervous system.
Which Breeds Are Predisposed To Testicular Tumors and Cancers?
Although intact canine males with a median age of 10 years are highly predisposed generally, breeds at increased risk include:
- German Shepherd
- Afghan Hound
- Shetland Sheepdog
Causes Of Testicular Cancer In Canines
Dogs with retained or undescended (testes that do not descend into the scrotum) testes have a propensity for Sertoli cell tumors and seminomas. Studies have indicated that cryptorchidism (absence of one or both testes from the scrotum) is one of the most important contributing factors to testicular cancer.
Apart from these age, breed and exposure to environmental carcinogens are other factors that attribute to tumorigenesis. Seminomas were commonly found among military service dogs who fought the Vietnam War. Studies have revealed testicular changes like testicular hemorrhage, epididymitis (Inflammation of the epididymis. It is a curved structure at the back of the testicle where the sperm is matured and stored), orchitis (inflammation, swelling and frequent infection of the testes), sperm granuloma (it is a lump of sperm that appears along the vasa deferentia or epididymedis in vasectomized men), testicular degeneration (most frequent cause of male infertility) and seminomas in these dogs. However, exposure to chemicals like herbicides, dioxin, or tetracycline are believed to have triggered tumorogenesis.
Testicular Tumor Symptoms To Look For
Testicular tumors can manifest in several forms, so a given pet may experience a few or an array of symptoms. Some of these signs could be any number of other medical issues. If your dog shows any signs of not being well, you should take them to a veterinarian for examination.
- Atrophy of the contralateral – shrinkage of the normal testicle
- Abdominal cavity or inguinal space – swelling and discomfort in these regions
- Feminization – due to a lack of testosterone production
- Bilaterally symmetric alopecia – loss of hair in spots
- Hyperpigmentation – skin discoloration
- Pendulous prepuce – suspended foreskin
- Gynecomastia – swollen mammary glands
- Glactorrhea – mammary gland blockages
- Penis atrophy – shrinking of the penis
- Hyperestrogenism – due to excessive estrogen production
- Blood Dyscrasias – abnormal blood chemistry
- Bone marrow hypoplasia – organ function and growth
- Pancytopenia – low white blood cells and red blood cells with platelets
- Hematuria – blood in the urine
- Spermatic cord torsion – twisted testical
- Hemoperitoneum – blood in the peritoneal cavity
Diagnostic Techniques For Canine Testicular Tumors
The diagnostic work-up may include fine-needle aspiration with cytology, rectal palpation, complete blood count, abdominal ultrasound and testicular ultrasonography.
- Fine needle aspiration cytology – is useful in screening for regional and distant metastasis
- Rectal palpation – denotes regional lymph node enlargement if there is any. Palpation of the prostate gland is mandatory.
- Complete blood count – is taken for examining hematologic abnormalities associated with hyperestrogenism like:
- Leukopenia – decrease in the number of white blood cells
- Thrombocytopenia – platelets count is relatively low
- Anemia – blood low in iron
- Abdominal ultrasound – scan doctors can identify non-descended testicles and regional lymph nodes
- Testicular ultrasonography – is helpful in differentiating between malignant conditions or cancer cells.
Treatment For Dogs With Testicular Tumors
Thankfully, most of the primary testicular tumors are non-metastatic. Orchiectomy (removal of one or more testicles or testes) with scrotal ablation is the treatment of choice for dogs with localized tumors. Since primary testicular tumors rarely metastasize, there is not enough information on their management procedures although there have been reports of systemic chemotherapy and radiation therapy.
Prognosis For Your Dog’s Testicle Tumors
Dogs treated with orchiectomy have a good prognosis. However, the outcome for dogs with bone marrow hypoplasia secondary to hyperestrogenism is guarded. According to some reports, dogs treated with system chemotherapy showed a median survival time of 5 months to 31 months.
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Withrow and MacEwen’s Small Animal Clinical Oncology – Stephen J. Withrow, DVM, DACVIM (Oncology), Director, Animal Cancer Center Stuart Chair In Oncology, University Distinguished Professor, Colorado State University Fort Collins, Colorado; David M. Vail, DVM, DACVIM (Oncology), Professor of Oncology, Director of Clinical Research, School of Veterinary Medicine University of Wisconsin-Madison Madison, Wisconsin
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