Now that you’ve read What is 'Staging' and Why Is it Important for the Pet Cancer Patient? and Staging for Canine and Feline Cancer Patients – The Blood Testing Stage, it’s time to move on to the next in this series.
Having covered the concept of staging and how blood testing is a crucial aspect of the staging process, let’s cover other bodily substances that can be evaluated in the process of determining where a pet sits in terms of being in remission or having determinable evidence of cancer.
Urine Testing — Urinary Tract Health
Most owners take their pet’s urine for granted until there is a problem, such as inappropriate urination, straining to urinate, bloody urine, or other alarming tendencies. In actuality, urine is a substance that serves a crucial role in the body and provides many key bits of information as to a pet’s overall health.
Urine is produced by the kidneys and is almost exclusively composed of water. The kidneys (along with the liver and digestive tract) function to remove harmful toxins and metabolic wastes from the body. Toxins can be ingested in food or water, absorbed through the skin, or produced through the process of day-to-day cellular functioning and activity.
Why Do Pets Need Urine Testing as Part of Their Cancer Treatment?
Many chemotherapy and other drugs commonly prescribed to pets are excreted through the kidneys and can potentially have the undesirable side effect of causing kidney damage.
Cyclophosphamide (Cytoxan) is cleared through the kidneys and can irritate the inner lining of the bladder and cause sterile hemorrhagic cystitis, where urine appears bloody and urinary patterns are altered. Increased water consumption is encouraged and a diuretic is given with the cyclophosphamide to help flush it from the body, which reduces the potential irritation of the inside of the bladder.
During Cardiff’s ongoing chemotherapy treatment, he’s received cyclophosphamide many times and has never shown any urinary tract side effects.
Some patients get cancers of the urinary tract, including the kidneys (renal carcinoma, etc.) or bladder (transitional cell carcinoma, etc.). As a result, the cancer itself can cause damage to the organs, which can lead to abnormal urinary patterns or urine testing results.
As a result of the potential for so many aspects of cancer and its treatment to affect urine, frequent urine testing is an important aspect of the staging process.
What Kinds of Urine Testing Are Performed on Pets?
Urinalysis is the basic component of urine evaluation; it reveals a complex story about urinary tract and whole body health.
Ideally, a urine sample is collected via cystocentesis, where a needle is placed through the abdominal wall into the pet’s bladder to attain a sterile sample. When evaluating urine for infectious organisms like bacteria, it's essential that the sample comes directly from the bladder—not from the ground where your pet just peed—to achieve accurate results.
Cystocentesis is most-safely performed with ultrasound guidance, as the bladder can be visualized before the needle penetrates its wall and evaluated for conformational problems (wall thickening, etc.) or the presence of other abnormalities (crystals, stones, etc.).
Non-cystocentesis urinalyses are considered contaminated, as one can’t determine if any bacteria discovered may have come from the tissues surrounding the opening of the urethra (the tube connecting the bladder to the outside world). Yet, non-cystocentesis samples can still yield important information.
Urinalysis is often paired with urine culture, where the sterilely-collected urine sample is placed onto nutritive media and the laboratory then repeatedly evaluates the sample for bacterial growth over a few day incubation period. If a urine cultures positive for bacteria, then the antibiotics to which the bacteria are sensitive can be determined through a process called Minimum Inhibitory Concentration (MIC). That way, the veterinarian can prescribe the most-appropriate antibiotic to treat a pet’s specific infection instead of simply selecting a drug that may or may not be effective.
Sometimes, bacteria can grow when a pet isn’t even showing clinical signs. This phenomena is called a subclinical infection and is important to resolve before the pet starts to exhibit urinary tract signs or incurs damage to other organs besides the bladder. Bacteria from the bladder can ascend into the ureters (paired, thin tubes that connect the kidney to the bladder) and cause kidney damage, which will further complicate the whole process of determining how well a pet is doing during cancer treatment.
Urine Specific Gravity (USG) reflects the kidneys’ ability to concentrate toxins in an effort to remove them from the body. If USG is too low, the cause may be traced to one of these conditions:
The kidneys may not be doing their job properly and your pet could be in some degree of renal (kidney) failure.
Your pet may be being stimulated to drink more water as a result of a non-kidney disease process occurring elsewhere in the body (hyperadrenocorticism, diabetes mellitus, etc.
You pet may be taking a medication that stimulates increased water consumption (corticosteroids, diuretics, etc.).
High solute (sodium, chloride, etc.) foods or beverages may be being consumed.
Elevated USG primarily occurs as a result of dehydration, when liquids in the body are concentrated in the tissues and there’s little excess to help flush out toxins through the kidneys.
Urinalysis also evaluates other aspects of kidney and other glandular function, including the presence or absence of glucose, bilirubin, ketones, protein, red blood cells, white blood cells, epithelial cells, mucus, casts, crystals, and more. Additionally, urinalysis takes into consideration the urine’s color, clarity, and pH.
Abnormalities in the any or all the above urine values can help paint a greater picture of health and tolerance of chemotherapy.
Fecal Testing — Digestive System and Intestinal Health
Like urine, we often take for granted our pets’ normal bowel movements until an abnormality arises. Owners are typically promoted to take action in seeking a diagnosis and treatment when poop appears on a fancy living room rug or diarrhea containing blood or mucus sprays the interior surfaces of one’s car.
Feces is the byproduct of food consumption and digestion and usually emerges from the anus just fine until dietary indiscretion (eating something one should not), food changes, digestive tract infections (parasite, virus, bacteria, etc.), or diseases (inflammatory bowel disease, cancer, etc.).
Abnormal bowel movements can also occur as the result of adverse responses to medications, supplements, or herbs.
Why Is Fecal Testing an Important Part of Cancer Treatment?
Fecal patterns help in the process of determining a pet’s quality of life. If a pet is constantly having diarrhea or is not able to stand and squat properly to pass a bowel movement, or the animal ends up frequently falling into its feces, then quality of life becomes less than ideal.
If your pet is undergoing treatment for cancer and his treatment is causing him to have diarrhea more often than normal stools, then his quality of life is lessened. Yet, is his diarrhea a result of his chemotherapy, gastrointestinal infections, food changes, or other ailment? Such isn't known unless baseline or advanced fecal testing is performed to help determine the underlying cause or causes.
In my veterinary practice, my canine patients are frequently out and about walking on sidewalks or in grassy areas in Los Angeles. As a result, they can come into contact with a variety of bacteria, viruses, and parasites in their day-to-day lives. I routinely perform baseline parasite screening every 3-12 months depending on their potential exposure to parasites (at parks, daycare, etc.).
Besides striving to keep the digestive tract parasite-free by pursuing a lifestyle of minimal exposure, eating a whole-food diet, taking intestine-sporting supplements (pre- and probiotics, etc.), knowing a pet’s parasite status before clinical signs of disease occur is a crucial wellness practice.
The baseline test I perform for fecal parasites is called an Idexx Fecal Panel Comp, which includes an Ova & Parasite evaluation under the microscope, and an ELISA (Enzyme Linked Immunosorbent Assay) test for giardia, hookworm, roundworm, and whipworm. This thorough evaluation is a great place to start.
If a patient has digestive tract signs and there are no parasites are turning up on the baseline testing, then advanced testing, like an IDEXX Canine or Feline Diarrhea Panel, can help find evidence of certain bacteria, viruses, and parasites that aren’t as common.
So, even though your pet may be undergoing cancer treatment and all energies are being focused on killing cancer cells, it’s crucial to keep up with routine monitoring of the urine, feces, and other aspects of whole body health.