Prostatic Adenocarcinoma (Prostate Gland Cancer) in Dogs
- Occurrence: rarer
- Location of illness: Abdomen/pelvis
Prostatic adenocarcinoma is a malignant tumor that develops from the glandular cells of the dog’s prostate gland. This form of prostate cancer is characterized by aggressive growth and a high tendency to metastasize. Unlike humans, where prostate cancer is one of the most common tumor diseases, prostatic adenocarcinoma is relatively rare in dogs. It accounts for approximately 0.2-0.6% of all canine malignancies. Nevertheless, this disease is of considerable clinical importance due to its poor prognosis and often late diagnosis.
The most important facts at a glance
Prostatic adenocarcinoma in dogs is a rare but aggressive tumor disease that primarily affects older male dogs. In contrast to benign prostate diseases, it occurs in both neutered and unneutered animals, with some studies even suggesting an increased risk for neutered male dogs. The exact causes are not fully understood, but genetic predispositions, hormonal factors, and environmental influences are discussed.
The clinical symptoms usually develop insidiously and mainly include disorders of urine and fecal output, hematuria, and non-specific symptoms such as weight loss and reduced performance. In advanced disease, neurological deficits can occur due to metastases in the spine. Diagnosis requires a combination of clinical examination, imaging procedures, and histopathological confirmation. Early metastasis screening is particularly important, as distant metastases are often already present at the time of diagnosis.
The therapy is based on a multimodal concept that may include surgical procedures, radiation therapy, chemotherapy, and targeted therapies. Despite therapeutic advances, the prognosis remains unfavorable, with median survival times of 6 to 12 months with optimal therapy. Aftercare focuses on regular check-ups, pain management, and maintaining quality of life.
Research in this area is constantly evolving, with promising approaches in targeted therapy, immunotherapy, and molecular diagnostics. A better understanding of tumor biology and the development of new therapeutic strategies could lead to improved treatment outcomes in the future.
Causes
The dog’s prostate is an unpaired, chestnut-shaped organ that surrounds the urethra and is located caudal to the bladder in the pelvic canal. It produces part of the seminal fluid and thus plays an important role in reproduction. Adenocarcinoma can develop in various areas of the prostate and typically spreads both locally invasively and via metastases in the body.
It is noteworthy that, in contrast to benign prostate diseases such as benign prostatic hyperplasia, which occurs predominantly in intact male dogs, adenocarcinoma can occur in both neutered and unneutered dogs. In fact, there is evidence that neutered male dogs may even have an increased risk of developing this type of tumor, although the underlying mechanisms are not yet fully understood.
The exact causes of prostate cancer in dogs are unknown. Hormonal factors, genetic predispositions, and environmental factors may play a role.
- Hormonal influences: Hormone status (testosterone) plays a crucial role in prostate health. Studies suggest that both intact and neutered male dogs can develop prostate cancer, although the situation is complex and other factors play a significant role.
- Genetic predisposition: Certain breeds (e.g., Golden Retrievers, German Shepherds) occasionally show clustering, but clear genetic markers are still being researched.
- Environmental factors: Exposure to environmental toxins or chronic Inflammatory conditions can increase the risk.
It is noteworthy that, in contrast to benign prostate diseases such as benign prostatic hyperplasia, which occurs predominantly in intact male dogs, adenocarcinoma can occur in both neutered and unneutered dogs. In fact, there is evidence that neutered male dogs may even have an increased risk of developing this type of tumor, although the underlying mechanisms are not yet fully understood.
The exact etiology of prostatic adenocarcinoma in dogs is not fully understood to date. In contrast to humans, where age, genetic factors, and hormonal influences are considered the main risk factors, the pathogenesis in dogs appears to be more complex. The following factors are discussed in current research:
Hormonal influences play a crucial, albeit paradoxical, role. While testosterone has a promoting effect in benign prostate diseases such as benign prostatic hyperplasia, adenocarcinoma appears to develop partly independently of androgen status. Recent studies show that neutered male dogs may even have up to four times higher risk of developing prostate cancer than intact animals. This suggests that the elimination of androgens may impair protective mechanisms or that other hormonal factors come to the fore.
Genetic predispositions are being increasingly researched. Certain dog breeds such as Dobermans, Scottish Terriers, Airedale Terriers, and medium to large mixed breeds appear to be more frequently affected. Molecular genetic studies have identified changes in various genes that may be associated with the development of prostate carcinomas, including mutations in the BRCA2 gene and overexpression of the COX-2 enzyme.
Environmental factors and chronic inflammatory processes are discussed as potential risk factors. Similar to humans, exposure to certain environmental toxins, heavy metals, or persistent organic pollutants could contribute to carcinogenesis. Chronic prostatitis could promote tumor development via inflammation-related DNA damage and oxidative stress.
Age is another important factor, as prostate cancer occurs predominantly in older dogs. The average age of onset is around 10 years, with a range from 6 to 17 years.
Symptoms
The clinical signs of prostatic adenocarcinoma in dogs usually develop insidiously and are often noticed only in advanced stages of the disease. This contributes significantly to the unfavorable prognosis, as metastases are often already present at the time of diagnosis. The symptoms result both from the local spread of the tumor and from possible distant metastases.
The characteristic symptoms include disturbances of urinary and fecal function. The enlargement of the prostate and the invasive growth of the tumor can lead to compression or infiltration of the urethra, which leads to dysuria (difficult urination), stranguria (painful urination with pressing), or pollakiuria (frequent Urinary urgency with small amounts of urine). In advanced cases, complete urethral obstruction with urinary retention can occur, which is a life-threatening emergency.
Similarly, compression of the rectum can lead to tenesmus (painful pressing during defecation) and constipation. Affected dogs often show a characteristic posture with a curved back and splayed hind legs during urination or defecation.
Hematuria (blood in the urine) is another common symptom that can be caused by tumor invasion into the urethra or bladder. Occasionally, hemospermia (blood in the ejaculate) also occurs, but this is rarely noticed by owners.
Systemic symptoms include progressive weight loss, inappetence, lethargy, and general performance decline. These non-specific signs are often an expression of advanced tumor disease and may indicate metastasis.
If metastasis occurs in the lumbar spine or pelvis, neurological deficits such as hind limb weakness, lameness, or paresis can occur. Lung metastases can lead to dyspnea (shortness of breath) and cough. Lymph node metastases can be noticeable as enlarged, palpable structures in the abdomen or pelvic area.
Schmerzen manifest themselves through Behavioral changes, reluctance to move, or vocalizations during urination or defecation. Pain assessment is an important aspect of clinical management and should be performed regularly.
Diagnosis
- Clinical symptoms: Difficulties in defecating and urinating, blood in the urine, Weight loss and decreased performance. Spinal pain is also possible, as prostate Tumors often metastasize in the area of the lumbar vertebrae.
- Rectal examination: Initial palpatory assessment of prostate size and shape.
- Imaging: Ultrasound, X-ray (especially thorax for metastasis search) and CT/MRI for an accurate representation of the tumor and potential metastases.
- Fine needle aspiration/biopsy: Histopathological examination for a reliable diagnosis of adenocarcinoma. Molecular tests (e.g., analysis of specific receptors or gene mutations) are under investigation.
The diagnosis of prostatic adenocarcinoma requires a systematic approach and combines clinical examination, imaging procedures, and histopathological confirmation. An early and precise diagnosis is crucial for therapeutic management and prognosis assessment.
The clinical examination begins with a thorough anamnesis, paying particular attention to changes in urination and defecation behavior as well as systemic symptoms. Rectal palpation allows an initial assessment of prostate size, shape, and consistency. Typically, the prostate affected by adenocarcinoma feels asymmetrical, irregularly limited, and hardened. The pain reaction upon palpation can vary.
Imaging procedures play a central role in diagnostics. Abdominal sonography allows a detailed representation of the prostate structure and can provide information on size changes, inhomogeneities, calcifications, or invasion into surrounding structures. Doppler sonography can also provide information about the vascularization of the tumor.
X-rays of the thorax are necessary for metastasis search, as the lung is a common site of metastasis. Abdominal X-rays can show prostate calcifications or displacement of neighboring organs.
Advanced imaging procedures such as computed tomography (CT) and magnetic resonance imaging (MRI) offer superior detail and are particularly valuable for assessing local tumor extension, lymph node involvement, and possible distant metastases. They are also important for therapy planning, especially if surgical intervention or radiation therapy is being considered.
The definitive diagnosis requires a histopathological examination of the prostate tissue. This can be done by fine needle aspiration, Tru-Cut biopsy, or surgical biopsy. Fine needle aspiration is minimally invasive, but offers less diagnostic certainty than tissue samples. Cytological examination typically shows cell clusters with clear malignancy criteria such as anisocytosis, anisokaryosis, prominent nucleoli, and increased mitotic activity.
Supplementary examinations include blood and urine analyses. Blood tests can provide information on paraneoplastic syndromes, Inflammatory conditions, or organ dysfunction. The urine examination can detect hematuria, pyuria, or secondary Urinary tract infection. A bacteriological urine culture is indicated if a concomitant infection is suspected.
Molecular and immunohistochemical investigations are becoming increasingly important. Markers such as Ki-67, PCNA, or p53 can provide information about the proliferation rate and the biological behavior of the tumor. In addition, specific receptors such as androgen or estrogen receptors can be analyzed, which has potential therapeutic implications.
Therapy
- Surgical approaches: A radical prostatectomy can be considered, but is technically demanding and associated with functional risks (incontinence, fistula formation).
- Radiation therapy: Can be used palliatively or curatively, often in combination with other procedures.
- Chemotherapy and targeted therapies: Certain protocols (e.g., based on doxorubicin or carboplatin) are used, the effectiveness of which varies. Newer studies on tyrosine kinase inhibitors or immune checkpoint inhibitors are promising, but are still in early stages.
- Hormones and castration: Castration alone does not appear to reliably prevent the development of adenocarcinoma, but can be useful for benign prostate changes (e.g., hyperplasia).
The treatment of prostatic adenocarcinoma in dogs poses a therapeutic challenge and usually requires a multimodal approach. The choice of therapy depends on the tumor stage, the patient’s general condition, and the available resources. Despite various treatment options, the prognosis remains unfavorable overall.
Surgical interventions include various procedures, of which total prostatectomy represents the most radical approach. This operation is technically demanding and associated with significant potential complications, including urinary incontinence, urethral strictures, or fistula formation. Newer, less invasive techniques such as partial prostatectomy or intracapsular prostatectomy are being explored to reduce the complication rate. Surgical therapy is often combined with adjuvant treatments to combat microscopic tumor residues.
Radiation therapy has established itself as a valuable treatment option, especially for non-resectable tumors or as adjuvant therapy after incomplete resection. Modern techniques such as intensity-modulated radiation therapy (IMRT) or stereotactic radiosurgery enable more precise irradiation of the tumor while sparing the surrounding tissue. Typical protocols include total doses of 45 to 54 Gy, divided into multiple fractions. Acute side effects can include cystitis, colitis, or dermatitis in the radiation field.
Chemotherapy is often used as a systemic treatment, especially in metastatic disease. Various protocols based on doxorubicin, carboplatin, cisplatin, or mitoxantrone have shown some efficacy. However, response rates vary greatly, and the duration of remission is often limited. Newer studies are investigating the efficacy of metronomic chemotherapy, in which lower doses are administered continuously, which can lead to an anti-angiogenic effect.
Targeted therapies are becoming increasingly important. Tyrosine kinase inhibitors such as Toceranib (Palladia®) or Masitinib have shown promising results in preclinical and initial clinical studies. These substances inhibit specific signaling pathways that are important for tumor growth and metastasis. COX-2 inhibitors such as Piroxicam or Firocoxib are also used due to their anti-tumor and anti-inflammatory properties.
Immunotherapeutic approaches are under development. Checkpoint inhibitors, which are already established in human medicine, are also being investigated in veterinary medicine. These substances reactivate the body’s own immune response against tumor cells. Initial studies with monoclonal antibodies against PD-1/PD-L1 or CTLA-4 show encouraging results in various canine tumors, including prostate carcinomas.
Palliative measures are an essential component of the therapy concept. They aim to improve the quality of life and alleviate symptoms. This includes pain therapy with NSAIDs, opioids, or adjuvant analgesics, ensuring urinary drainage through catheterization or stent implantation, as well as supportive measures such as fluid therapy, nutritional management, and physiotherapy support.
Prognosis and follow-up care
The prognosis for dogs with prostate cancer is generally poor, as the disease is often already advanced at the time of diagnosis. Treatment strategies aim to improve the quality of life and slow the progression of the disease.
- Tumor stage: Early detection is essential for the prognosis, as prostate cancer can quickly metastasize to the lungs, lymph nodes, or bones.
- Quality of life: With comprehensive therapy (surgery, possibly radiation therapy/chemotherapy), the symptoms can often be alleviated. Nevertheless, prostatic adenocarcinoma remains a serious diagnosis.
- Long-term survival: Depending on the aggressiveness and metastasis, survival ranges from a few months to over a year. An interdisciplinary approach (oncology, surgery, pain management) improves the quality of life.
Aftercare
- Regular check-ups: Examinations of prostate size, blood and urine analyses, as well as imaging procedures (X-ray/ultrasound/CT) are advisable at intervals of 3 to 6 months.
- Symptom-oriented management: Pain therapy, stabilization of urinary and fecal passage (if necessary, soft food, stool regulation).
The prognosis for dogs with prostatic adenocarcinoma is generally unfavorable, mainly due to the late diagnosis and the high rate of metastasis. Various prognostic factors influence the course of the disease and survival time.
The tumor stage at the time of diagnosis is the most important prognostic factor. Dogs with localized disease have a better prognosis than those with regional lymph node involvement or distant metastases. Unfortunately, approximately 40–80% of prostatic adenocarcinomas are diagnosed only in the metastatic stage, which limits the therapeutic options. The most common sites of metastasis are the lungs, regional lymph nodes, liver, bones (especially the lumbar spine and pelvis), and kidneys.
Histopathological features such as the degree of differentiation, mitotic rate, and invasiveness of the tumor correlate with the prognosis. Highly undifferentiated tumors with high mitotic activity typically show a more aggressive biological behavior and are associated with shorter survival times.
The median survival time after diagnosis varies depending on the therapy and tumor stage. Without specific treatment, it is approximately 1–3 months. With multimodal therapy approaches, the survival time can be extended to 6–12 months, with individual patients also achieving longer survival times. After total prostatectomy, median survival times of 3 to 14 months are reported, while radiation therapy can lead to median survival times of 5 to 12 months.
Follow-up care plays a crucial role in the management of dogs with prostatic adenocarcinoma. Regular check-ups should be performed at intervals of 1 to 3 months, depending on the patient’s clinical condition and the chosen therapy. These examinations include:
Clinical evaluation with particular attention to urination and defecation behavior, pain assessment, and neurological status. The quality of life should be systematically recorded, for example, through validated questionnaires or scoring systems.
Imaging procedures to assess the response to therapy and for early detection of recurrences or metastases. Thoracic radiographs, abdominal sonography, and, if necessary, CT/MRI examinations should be performed at regular intervals.
Laboratory tests including complete blood count, serum biochemistry, and urinalysis to monitor organ function and to detect possible therapy side effects.
Pain management is a central aspect of follow-up care. The analgesic therapy should be evaluated regularly and adjusted if necessary. A multimodal approach with NSAIDs, opioids, gabapentinoids, and local anesthetics may be necessary, especially in patients with bone metastases.
Supporting the owners through detailed education, psychological support, and practical assistance with home care is also important. The decision for euthanasia may be necessary in advanced stages of the disease and should be made in close consultation with the owners, with the animal’s quality of life being the priority.
Prevention
There is no guaranteed method for preventing prostatic adenocarcinoma in dogs, but castration reduces the risk of other prostate diseases, which indirectly facilitates early detection. From middle age onwards, male dogs should be examined rectally on a regular basis to detect changes early. Symptoms such as difficulty passing feces or urine, blood in the urine, or lameness in the hindquarters must be taken seriously. A healthy diet, normal body weight, and sufficient exercise promote general health. Genetic predispositions should be taken into account when selecting breeding animals. Early veterinary check-ups are the most important preventive approach.
Outlook on current research
Research on prostatic adenocarcinoma in dogs has made significant progress in recent years, opening up new diagnostic and therapeutic perspectives. Current research focuses on molecular characterization, innovative therapeutic approaches, and translational aspects.
In the field of molecular oncology, genetic and epigenetic changes that contribute to the development and progression of canine prostate carcinoma are increasingly being identified. Genome-wide sequencing studies have revealed specific mutations and chromosomal aberrations that could represent potential therapeutic targets. Changes in genes such as PTEN, TP53, and BRCA1/2, which also play a role in human prostate carcinoma, are of particular interest. The identification of specific molecular subtypes could enable more precise prognosis and individualized therapy planning in the future.
Liquid biopsy procedures are being intensively researched to develop non-invasive diagnostic and monitoring options. The analysis of circulating tumor cells, cell-free DNA, or exosomes in the blood could revolutionize early detection, therapy monitoring, and recurrence diagnostics. Initial studies show promising results in the detection of tumor-specific biomarkers in the blood of dogs with prostate carcinoma.
In the field of imaging, new techniques such as molecular imaging with tumor-specific tracers are being developed. PET-CT scans with radiotracers such as 18F-FDG or more specific markers could improve the sensitivity and specificity of tumor diagnostics and metastasis screening.
Innovative therapeutic approaches are the focus of numerous clinical trials. Immunotherapy with checkpoint inhibitors such as anti-PD-1/PD-L1 antibodies shows promising results in initial studies in various canine tumors. Specifically for prostate carcinoma, combinations of immunotherapy and conventional treatments are being evaluated to exploit synergistic effects.
Targeted therapies are being increasingly refined. In addition to established tyrosine kinase inhibitors, new substances are being developed that specifically target molecular changes in prostate carcinoma. PARP inhibitors, which are particularly effective in BRCA-mutated tumors, are being tested in preclinical models.
Local ablation procedures such as high-intensity focused ultrasound (HIFU), cryotherapy, or photodynamic therapy are being evaluated as minimally invasive alternatives to surgical resection. These techniques could be particularly relevant for patients with localized disease and increased surgical risk.
Translational research approaches are becoming increasingly important. Canine prostate carcinoma has remarkable similarities to aggressive, androgen-independent prostate carcinoma in humans and could therefore serve as a natural model for this difficult-to-treat disease. Comparative studies that examine molecular and clinical aspects in dogs and humans in parallel could lead to new insights for both species.
The integration of artificial intelligence and machine learning into diagnostics and therapy planning represents another promising area of research. Algorithms for analyzing histopathological images or for predicting therapy response are being developed and could support clinical decision-making in the future.
Despite these promising developments, challenges remain. The rarity of the disease makes it difficult to conduct large clinical trials, and the transferability of preclinical results into clinical practice must be carefully evaluated. Multicenter collaborations and the establishment of biobanks and registries could help to overcome these hurdles and accelerate progress in research and therapy.
Frequently asked questions (FAQs)
1. What is Meant by Prostatic Adenocarcinoma in Dogs?
This is a malignant tumor in the prostate gland of male dogs that originates from glandular cells. According to Withrow & MacEwen’s Small Animal Clinical Oncology, prostate carcinomas are rare but often aggressive.
2. What Signs Indicate Prostate Cancer in Dogs?
Problems with urination or defecation, blood in the urine, chronic hind limb weakness, or pain in the lumbar region may be indications. petsvetcheck.de emphasizes that increased licking of the genital region or unusual changes in posture may also be noticeable.
3. How is the Diagnosis Made?
- Rectal palpation: First indication of an enlarged or irregular prostate.
- Imaging diagnostics: Ultrasound, X-ray, CT/MRI.
- Tissue sampling: Fine needle aspiration or biopsy to histologically confirm the adenocarcinoma.
The BSAVA Manual of Canine and Feline Oncology also recommends a comprehensive metastasis search (chest, abdomen).
4. What Role Does Castration Play in Prostate Cancer?
While castration prevents benign prostatic hyperplasia, it does not reliably protect against malignant tumors. Some studies even discuss whether neutered male dogs may have a higher risk of developing certain prostate tumors. However, the data is not conclusive.
5. What Treatment Methods are Available?
- Radical surgery (prostatectomy): In suitable cases.
- Radiation therapy: especially for locally advanced tumors.
- Chemotherapy: as a supplement or palliative measure for advanced disease.
Newer research is concerned with targeted therapies (e.g. tyrosine kinase inhibitors).
6. Is a Cure Possible?
A complete cure is only possible in rare cases and with very early diagnosis. In most cases, the tumor can be controlled, but not completely eliminated. According to Slatter’s Textbook of Small Animal Surgery, a lot depends on the tumor stage and metastasis.
7. What is the Risk of Metastasis?
The risk of metastasis (primarily in bones, lungs, and lymph nodes) is comparatively high in prostate carcinomas. Therefore, regular follow-up examinations (e.g. lung X-rays, lymph node check) are important.
8. What is the Prognosis for a Dog with Prostate Cancer?
The prognosis is generally guarded. However, with early detection and consistent therapy, the dog can still live for several months to over a year with a good quality of life. The later the tumor is discovered, the lower the chances of success.
9. What Aftercare is Recommended?
- Check-up examinations: approximately every 3–6 months.
- Pain management: Important if metastases form in the bone.
- Physiotherapy/Supportive measures: As needed to maintain mobility and well-being.
10. How Can I Improve My Dog’s Quality of Life?
A low-stress environment, adapted exercise, and need-based pain relievers or medications to improve bladder and bowel passage are crucial. Regular veterinary check-ups ensure early intervention in the event of possible complications (e.g. urinary retention).