Cancer in dogs bladder cancer in the urine
About 2% of all greyhound cancer cases recorded so far are urinary bladder cancers. The number of deaths from urinary bladder cancer in dogs, which number more than 60 million in the USA, is rising quickly. There are many different kinds of bladder tumors, including squamous cell carcinoma (which develops in epithelial cells), adenocarcinoma (which develops in glandular epithelium), undifferentiated carcinoma, rhabdomyosarcoma (which develops in striated muscles, which are made up of parallel fibers like those in the skeletal and cardiac muscles), and fibroma (which develops in fibrous or connective tissue).
They can develop in any organ region that has mesenchymal tissues, as well as other, less common mesenchymal tumors (tumors that develop from soft tissues). However, the most typical form of canine urinary bladder cancer is invasive transitional cell carcinoma, or TCC. Most TCCs are papillary proliferative lesions that range in grade from intermediate to high. The trigone (a smooth triangular portion of the interior urinary bladder) is where TCCs are most frequently discovered. Breeds with a high propensity for this condition include Scottish terriers, Shetland sheepdogs, Airedale terriers, Beagles, West Highland white terriers, and Wirehaired Fox Terriers.
There are many possible causes for urinary bladder cancer. The most likely risk factors are thought to be topical pesticide and herbicide exposure, obesity, cyclophosphamide treatment, and specific breeds. Female preference has been proven to be a prominent component in the great majority of research.
World Health Organization's Clinical Staging System (WHO)
T - Initial tumor
Carcinoma in situ, or *Tis (early type of cancer)
* T0- No sign of a primary tumor * T1- Superficial papillary tumor * T2- Tumor infiltrating the bladder wall with induration (hardening of the bladder wall as a result of infiltration of neoplasm [abnormal growth of tissue]) * T3- Tumor encroaching on nearby organs (prostate, uterus, vagina and pelvic canal)
Local lymph node N (internal and external iliac lymph node)
* N0- No involvement of regional lymph nodes * N1- Involvement of regional lymph nodes * N2- Involvement of both regional and juxtaregional lymph nodes
M - Remote metastases
Courtesy of Withrow and MacEwen's Small Animal Clinical Oncology * M0- No evidence of metastasis * M1- Present distant metastasis
The wall of the urinary bladder is shown to be thicker in dogs with TCC. Additionally present are papillary lesions. These can partially or totally cause a dog's urinary tract obstruction. Lesions have been seen in both the bladder and the urethra, according to recent studies. Prepubic cystotomy catheters that avoid urethral blockage have been tried on certain dogs with poor outcomes. This procedure involves opening a cyst or cutting into the bladder to remove calculus.
Hematuria (blood in the urine), dysuria (painful urination), pollakiuria (frequent midday urination), and occasionally lameness brought on by hypertrophic osteopathy are examples of clinical symptoms (bone disease). The duration of the symptoms might range from days to weeks to months.
Rectal examination, complete blood count (CBC), serum biochemistry profile, urinalysis, urine culture, radiography of the thorax and abdomen, and bladder imaging (contrast cystography or cystosonography) are all necessary for the diagnosis of bladder cancer.
Rectal examination may indicate a tumor in the bladder, a swollen bladder, thickening of the urethral or trigone region of the bladder walls, or enlarged iliac lymph nodes.
Urine can be collected by free catch or catheterization to reduce the risk of tumor seeding, which is the dispersal of tumor cell clusters and their subsequent growth at a location next to the original tumor, during cystosyntesis (a procedure in which a needle is inserted into an animal's urinary bladder through the abdomen and a sample of urine is removed). When placing a catheter, extreme caution must be used because the slightest brush could cause the diseased bladder or the urethral wall to rupture.
The bladder must be inflated before beginning a cystonography. An urinary catheter is used to inject 4–8 ml/kg of sterile saline into the bladder to accomplish this.
Viewing the local lymph nodes and metastases in other abdominal organs with ultrasound is crucial.
Neoplastic cells in the urine of at least 30% of dogs cannot be distinguished from reactive epithelial cells linked to inflammation, making histopathology (the microscopic inspection of tissues) significant. Cystotomy (bladder incision), cystoscopy (a diagnostic procedure used to view the bladder [lower urinary tract], collect urine samples, and evaluate the prostate gland), and traumatic catheterization are methods for acquiring tissue for histopathologic research.
TCC has occasionally been observed to spread to the bones. In order to rule out bone metastases in the event of unexplained lameness, radiographs and a nuclear bone scan must be compared side by side.
Due to the lesion's trigonal position and urethral involvement, complete surgery is not possible. The median survival rate and the length of remission, however, were substantially lower. Partial cystectomy (removal of a portion of the urinary bladder) is advised for individuals whose tumor is on the apex of the bladder.
When a dog has a distal urinary tract obstruction, surgery is typically utilized as an emergency, palliative procedure to debulk (remove extra tissue from a lesion) inoperable tumors. Prostate will also be thought to be involved in males.
Radiation therapy is used to slow the growth of tumors locally, but it has a number of side effects, including urinary incontinence (unwanted urination), cystitis (inflammation of the bladder), pollakiuria, and stranguria (difficulty with urination). Numerous dogs have reported complications following pelvic irradiation. Weekly course fraction beam radiation therapy, mitoxantrone, and piroxicam chemotherapy were used to treat ten dogs. They significantly improved. However, when treated with mitoxantrone and piroxicam therapy without radiation, the data revealed a decline.
The highest rate of remission in dogs was achieved when cisplastin and piroxicam were administered. But it's thought that this combo damages the kidneys. Piroxicam may potentially obstruct renal blood flow in addition to directly damaging renal tubule cells. In one research, the administration of piroxicam together with carboplatin caused remission in 38% of patients. Additionally, multifocal TCC on the bladder is common in dogs. In contrast, 35% of dogs in a different research who received piroxicam with mitoxantrone had a median survival length of 291 days. The use of piroxicam alone has produced positive outcomes.
Based on the size of the tumor, the illness stage, and the degree of metastasis, the course of treatment should be chosen. The current regimen should be continued if the lesions are modest and stable. After complete remission, treatment is continued for an additional 4–8 weeks in the hope that any remaining microscopic signs of the illness would be eliminated. Some medical professionals advise piroxicam usage for life. However, if the illness is discovered to be progressing or toxicity is found, treatment is terminated.
Photodynamic treatment (PDT) research is currently being conducted. PDT with 5-aminolevulinic acid (ALA) effectively kills canine TCC cells in a culture dish (a technique of performing a procedure in a controlled environment outside of a living organism). Five dogs received ALA-based photodynamic treatment for TCC, which resulted in tumor progression-free intervals of 4-34 weeks. Additionally, it was used in a male dog who had urethral TCC. Even a year after therapy, it was discovered that this dog was disease-free.
TCC canine patients are more likely to get secondary bacterial infections. Urinalysis and urine culture should be done periodically. Catheterization, definitive anti-cancer therapy, medicines to decrease inflammation brought on by secondary bacterial infection, or surgical debulking are typically advised if obstruction of the urinary tract arises. In dogs with urethral TCC, prepubic catheters are occasionally placed and left in place for several months. In order to ease urethral obstruction and achieve urine diversion, a low-profile gastrotomy tube (feeding tube) has been utilized as a prepubic cystotomy tube.
Dogs with TCC inevitably pass away from it because of how insidious and widespread the disease is. But because to things like early discovery, prompt treatment, tumor size, and metastasis extent, many dogs survive. According to numerous research, the median survival time is greater than 6 months. In 20% of dogs treated with piroxicam, the median survival was found to be greater than one year. Younger dogs with prostate involvement and extensive metastases appear to have a higher disease severity at the time of diagnosis. Poor prognosis is indicated by advanced metastasis and glandular differentiation in the histopathologic investigation at the time of diagnosis (presence in a carcinoma of glands and gland-like features which, implies some maturation).