Understanding the Causes and Symptoms of Blood in Cat Urine

1. Introduction

Blood in cat urine is a condition that warrants prompt veterinary intervention. Bloody urine, called hematuria, can be a sign of a bacterial infection, bladder stones, tumors, or idiopathic feline cystitis. Educated cat owners who know the signs of urinary problems can seek medical attention for their pets to avoid complications, including kidney failure that may result from untreated blockages or infections of the urinary tract. There are several causes for blood in cat urine, each with its own set of treatment protocols. The symptoms are basically the same; however, only thorough testing by a veterinarian can determine the underlying problem. After diagnosis, treatment may involve supportive care, watchful waiting, or surgery. Treating urinary problems in cats isn’t just a matter of giving them a shot of antibiotics and sending them home. Because there are so many possible causes, treatment for bloody urine can be as simple as rehydration to surgery and a change in diet. Treatments are also populated by a long list of prescription and over-the-counter medications that can be given to your cat during potty troubles, some that allow for immediate relief and others that need to be given daily for weeks or months at a time. You might give your cat some immediate relief while waiting for a visit to the veterinarian.

In many cases, the presence of otherwise unseen blood in the urine or litter is the first indication of a medical problem. Several conditions can lead to blood in the urine of both male and female cats, including infections, abnormalities in the urinary system, or other causes such as trauma. Different tests help veterinarians diagnose the cause of this condition; in female cats, a thorough physical examination and a pair of urine and blood tests are generally the tests of choice. The prevalence of urinary tract issues in the feline species warrants discussion on this topic: the vast majority of senior cats, approximately 58.2% of cats aged 10-14 years, suffer from this condition in at least some form.

1.1. Purpose of the Study

Urine normally ranges in color from clear yellow to light yellow for cats. Certainly, it is vital for individuals to be well acquainted with common changes in their felines and the possible accompanying harmful effects. One such deviation is blood in your cat’s urine. Although it may not be a specific diagnosis, the presence of blood in feline urine is a possibly serious complication, warranting the direct counsel of a qualified veterinary professional. Indeed, the identification of factors influencing urinary health would significantly aid an owner’s capacity to deliver immediate care or swiftly seek professional intervention for their cat. Promoting feline welfare within companion animals is a relevant priority for our communities. As the management of multiple health combinations also alters the origin and range of accompanying clinical signs, an awareness of symptoms displaying blood in the urine is critical.

Should a vet verify the entirely non-fatal existence of blood in their urine, then propagation of knowledge regarding the condition entailing such correlated signs is also required. Studies conducted with the purpose of categorizing and justifying explicit observations could produce a more satisfactory acquisition of wisdom in how to similarly tackle and modernize therapeutics. Urinary and bladder health problems in cats are quite common and can definitely be painful, particularly if left without treatment. It’s important to understand that the symptoms can be similar but the causes and treatments can be very different, and in many instances, timely medical intervention is very helpful.

2. Anatomy and Function of the Feline Urinary System

The urinary system is an important component of feline anatomy that is responsible for the excretion of excess waste materials and maintenance of proper hydration. Central to the system are two bean-shaped organs called kidneys, whose function it is to produce urine. The ureters are a pair of hollow tubes that connect the kidneys to a muscular storage area referred to as the bladder. Once the bladder is full, its contents are micturated out of the body through a tube called the urethra. Simultaneously, the bladder sphincter, which is a circular muscle, contracts to prevent the release of urine until an appropriate time. Although the components of the feline urinary system are similar in female and male animals, minor differences in anatomy can result in unique complications and potential health issues. In male cats, there is a branching of the inside of the urethra upon entry into the pelvic bones, resulting in a longer urethra channel than inside a female. The anatomy increases the occurrence of feline lower urinary tract obstruction in males compared to females.
The feline urinary system is responsible for ridding the body of waste in the form of urine. Blood is filtered by the kidneys, and the urinary system helps regulate electrolytes, clean the blood, and maintain appropriate hydration. Feline urine then travels to the bladder through two small tubes called the ureters, which then pass to the urethra. The external opening of the urethra allows pets to empty their bladder. This extensive system works cohesively to keep the body healthy by detoxifying blood and removing waste materials. Each individual part of the urinary system interconnects with another part to keep the process of making and removing urine functional. Occasionally, the anatomy of the urinary system will differ in cats, which may make them more susceptible to certain urinary issues. When malfunctions in the urinary system occur, signs of disease typically appear. Possible issues with the urinary system in cats will be outlined in the Symptoms section. Not only does the overall anatomy of the urinary system determine how susceptible a cat may be to urinary issues, but regularly functioning parts can change as well. As the cat ages, the kidneys perform less effectively, and the amount of water they drink decreases. Old male cats can also develop urethral plugs in the penis that can block the flow of urine. Several breeds of cats, especially the Siamese, also seem to be at greater risk of developing the disease.
Understanding the structure and function of the feline urinary system is the foundation for evaluating any associated urinary or bladder health issue. Additionally, it informs the progression of appropriate diagnosis and treatment. Whether you are a veterinary professional or a pet owner, knowledge of the urinary system is important when discussing and addressing specific health issues.

2.1. Overview of the Urinary System

The urinary system, also called the renal system, includes the kidneys, ureters, urinary bladder, and urethra. Its primary functions are to remove metabolic waste products and maintain the balance of fluid and electrolytes. Kidneys play a central role in the urinary system, acting as excretory organs that filter waste from blood and regulate the concentrations of many substances. Every 30 minutes or so, the kidneys filter all of the blood in the body. Either the substances filtered out of the blood attach to the substances in urine and go out of the body, or the needed nutrients from the waste products are returned to the blood. Any waste products and extra fluid become urine. The interface where the functions of the respiratory, muscular, and urinary systems come together is the bladder. It stores urine until release. An internal sphincter at the lower end of the bladder is also part of the bladder.

In most situations, both the involuntary muscles of the bladder and the sphincter are relaxed, allowing drainage of urine into the urethra. Though the sphincter is relaxed, the brain sends messages to the surrounding circular muscles of the urethra to stay tight. As the volume of urine in the bladder increases, the bladder wall stretches out and receptors in the bladder send signals to the brain. This signal results in a few drops of urine release because the pressure buildup has become intolerable. With more stretching, the feeling becomes urgently intolerable. The muscles of the bladder wall will start contracting, the internal sphincter relaxes more, and urine is eventually expelled. Issues can occur in different areas of the urinary system and result in various clinical symptoms. The kidney and urinary bladder are the most interactive systems, and it is where clinical signs are most often detected.

3. Common Causes of Blood in Cat Urine

Blood in cat urine is a symptom called hematuria. Hematuria occurs in a variety of diseases. In the urinary system itself, urinary tract infections, crystals, and stones can cause the lining of the bladder or the urethra to bleed. Any relationship with other organ systems in the body, with trauma, or even with tumor cells can cause bleeding in the urine. Usually, in quite routine conditions, the appearance of blood in urine can subside. But there are also cases where urine bleeding is chronic, which means it occurs more than three times a year. Hematuria is a severe case seen as very alarming and frightening for some cat owners because the presence of blood in the urine can affect the cat's life, making it weaker and easily tired. Environment, certain diets, and management accompanied by a lack of water can be some of the factors that cause stones and crystals. The common causes of the occurrence of blood in cat urine are: functional or idiopathic hematuria, urinary tract infection or inflammation of the bladder that causes irritants and infections, crystals/urethral plugs, and stones that cause obstruction in urination, which may require the cat to undergo surgery or euthanasia, urethritis, and others. Common urinary symptoms include straining, increased frequency, discomfort, inappropriate urination, or apparent pain during urination. Less common but severe dysfunction includes chronic or recurrent urinary retention, including urinary incontinence or urinary obstruction. Rupture or exposure of the bladder may occur in severe cases if it remains untreated. Hematuria can be self-limiting, recurrent, or chronic. Finding and understanding the underlying causes will facilitate early diagnosis and appropriate treatment.

3.1. Urinary Tract Infections

Urinary Tract Infections: Reasons for Blood in Cat Urine

A urinary tract infection (UTI) is one of the main causes of blood in cat urine. Most of these infections develop as the result of fecal contamination. A cat’s urinary tract is not sterile. However, the normal bacterial flora is usually harmless and does not cause any disease. It is only when fungi, viruses, or pathological bacteria invade the urinary tract that it becomes inflamed. This inflammation can cause hyperemia and breakdown of blood vessels, leading to the shedding of bloody urine from the body. As the inflammation may include the urinary bladder, the urethra, and the ureters, there are various parts of the urinary system that could be the source of the blood. In general, urinary tract infections are accompanied by several symptoms. The bacterium may irritate the lining of the urinary bladder, which causes pain and discomfort. This could lead to a severe urge to pass urine. The cat thus has to visit the litter box more frequently than usual. Furthermore, the urethra and the muscles of the pelvis may also get infected and inflamed. In such cases, the cat may experience general malaise.

Poor hygiene is one risk factor that can lead to infection of the urinary tract in cats. The predisposition to UTIs might also be due to some anatomical reasons. In such cats, a UTI may develop in the urethra, which can then wreak havoc on the urinary bladder as well. Bacterial infections may also occur following surgery. The area around the incision is usually cleaned and sterilized prior to treatment. Also, most treatments are carried out in a sterile operating room. However, there are still potential sources of infection, and bacteria might enter an incision and cause an infection. Moreover, if the cat doesn’t get up and move around frequently following surgery, it might invoke a decreased urine flow, leading to urinary stagnation. The presence of heavy sutures or staples could also lead to a urinary blockage. This could consequently lead to urinary stasis and predispose the urinary bladder to pyocystis. Proper diagnosis and therapy are very important. If left untreated, a UTI in cats could lead to complications like pyelonephritis. In order to prevent such infections in cats, a high standard of hygiene should be maintained. Encouraging the cat to move around after a surgical intervention is equally important. Flushing the urinary bladder on a regular basis will keep it clean while also preventing urine accumulation.

3.2. Bladder Stones

Bladder stones, also called calculi or uroliths, are extremely common in cats. They form when mineral compounds start to accumulate in the urine and cause small particles to adhere to one another, creating hard, mineralized balls of varying size and composition. The body of an adult animal, including the cat, is adapted to handle a certain "normal" load of minerals, but when levels start to exceed that capacity, stones can develop. Bladder stones occur for a variety of reasons, but some animals are simply more acidic or alkaline, or they struggle to metabolize certain minerals, thereby providing the perfect environment for stones to form. Bladder stones can irritate the walls of the urinary tract as they pass through the system, leading to bleeding. It appears to work similarly to a bladder infection in this regard, with fragile vessels on the surface of the bladder and urethra breaking and leaking red blood cells.

The most obvious symptom is blood in the urine, but other signs may be more subtle. Owners may notice they are scooping the box more frequently, their cat is straining or crying out while urinating, or that they are leaving small amounts of urine in random places around the house because it is too uncomfortable for them to make it to the box in time. Similarly, a cat with blood in the urine tends to receive a great amount of attention from owners. Although many of the causes of blood in the urine are highly treatable, the emotional and financial investment required of a pet owner is significantly daunting. Some breeds, such as Siamese, Himalayans, Cornish and Devon Rex, and the Scottish Fold, may have an increased risk of developing bladder stones. One dietary theory suggests that high levels of plant material in the diet may influence struvite production, but the best "stone prevention" diet is still subject to intense debate. In general, cats with a history of bladder stones should drink plenty of water, eat a high moisture, low ash, and low magnesium diet made of primarily or exclusively animal-based foods. It has been suggested that chronic potassium deficiency leads to a more alkaline urine, tripling the risk of struvite stone formation. Offering monitored doses of potassium citrate solutions to cats with a history of struvite stones will reduce urinary particulate mineral struvite formation in about 30% of cats within two months. Also, feeding a diet with a moisture content above 81% successfully dissolves struvite stones in about 80% of cases when the given diet has supervised compliance. Various methods of drug treatment are also available, but these are best pursued in concert with a veterinarian. Surgical removal of bladder stones is necessary in prolonged or severe cases.

3.3. Urinary Tract Tumors

Urinary Tract Tumors. These form the third most common benign neoplasia group and represent the second most common cancerous tumors in the feline geriatric population. The feline urinary system can be affected by both benign tumors and malignant tumors. Fibromas can be seen anywhere in the urinary system, but they primarily occur in the bladder in cats. Other benign tumors can also occur in the area of the kidneys and the urinary system, but also in the urethra. Feline urinary tract cancer is primarily characterized by carcinoma. They originate from the epithelium, which covers the lining of the urinary tract.

Benign tumors develop primarily in adult and elderly cats but can also develop in juvenile cats. Malignant tumors are more common in cats from 9 to 15 years of age. Urinary tract tumors act inside the affected organ in a very similar way, regardless of whether it is a benign or a malignant tumor. Benign tumors are primarily removed by surgery, and in benign tumors with a large front extension of exophytic character, chemotherapy reduces recurrence, provided that the tumor cells have a suitable antigen. Tumors of the urinary system, which are a very frequent cause of visible hematuria, are often asymptomatic, especially in the early stage of development, making an accurate diagnosis difficult until the tumor grows large enough to lead to blockage of the urinary flows. The cat begins to show their first symptom, often of a urinary character. Such symptoms are accompanied by visible hematuria, usually gross. In addition, general symptoms such as a more or less severe loss of appetite, gradual emaciation, and general weakness may be present. The disease develops very gradually, and urination and dilatation of the bladder can last for weeks or even months from the beginning of the first symptoms. A great deal of neoplasias occurs at the trigone point and develops very large among the interior and exterior layers, which is why their removal is laborious.

4. Symptoms and Clinical Presentation

Some cats with blood in their urine will have no clinical signs, and it is only when noticed in the litter box that there is any cause for concern. If a cat is symptomatic, the presentation can vary widely and may, in part, depend upon the underlying cause and the severity of the disease. Common signs are that the cat will urinate outside of the litter box or have increased frequency of urination. Painful urination refers to an uncomfortable feeling and results in straining or crying when urination occurs. Observing a cat straining to urinate is very significant, and in males with a history of near-obstructive signs, it could be a life-threatening emergency; thus, immediate veterinary help should be sought. Other clinical signs may be more subtle and could be present with benign disease. In addition to obstructive signs, cats could have increased thirst, and this leads to signs associated with increased urine volume, such as needing to urinate outside of the litter box.

Even 'non-painful issues' will need further attention but may not be immediate if the cat is stable and receiving veterinary attention. In general, cats that are eating and drinking normally generally feel fine, but with a noticeable increase in thirst and possibly using the litter box more often. A benign presentation includes normal thirst and a large amount of red-tinged urination around the house. Blood is not noticeable in the litter box, or the urination in the box is increased. Blood is found in urination in the box. A more severe presentation includes increased thirst; about 50% of the maximum amount of urine may be passed around the house or in the box, and in males with a history of near-obstructive signs, straining to urinate. Blood is associated with urination around the house and an increased frequency to urinate in the box. Blood with urination in males can be with or without straining and either in the litter box or outside of the litter box. Hematuria that is believed to come from the bladder but does not cause frequent or near-constant pain will be less of an emergency. Observing your cat for signs of stranguria (straining or vocalization while urinating), frequent urination, and erratic litter box use can provide vital information for the veterinarian. Testing is often indicated if any of these symptoms occur, especially if the owner notes a cat crying out in the litter box, which represents a urinary tract emergency. The fact that where the symptoms are seen in the litter box can, in some cases, provide a clue as to the location of the urinary system that is affected. For example, cats with kidney disease will often produce large volumes of clear, light yellow or green-tinged urine, which can be seen close to the box walls. They may also urinate outside of the box, potentially in other areas of the house away from the others and with a normal pattern of elimination.

4.1. Visible Blood in Urine

Visible loss of blood in urine is one of the most important clinical signs. It can appear as a discoloration of the urine or as large clots. Blood can present itself right away or after a while. Sometimes, the urine does not appear discolored, but there are visible blood clots in the urine. The presence of blood in urine causes and aggravates discomfort. Hematuria can appear without causing symptoms, or it can be accompanied by general and/or urogenital signs. It is noteworthy that one and the same cause of hematuria may have different symptoms.

It is essential to determine in which part of the urinary tract the blood loss occurs because the causes of hematuria are specific for each segment. A distinction is made between microscopic hematuria and visible hematuria. Microscopic hematuria is detected with a urine sediment test or with a laboratory test and tends to be missed by the owner. Visible hematuria indicates a more severe lesion and is easily discovered by the cat owner who consults the veterinary surgeon. The loss of an important quantity of visible blood in the short term necessitates a rapid examination. The origin of this loss could be extra-urogenital: trauma, bone marrow problems, more or less severe infectious diseases, poisoning. Nevertheless, if the inflammation spreads, visible hematuria appears in these organs. In this case, relief is more important than the loss of urine, which does not require an immediate visit to the veterinarian.

4.2. Frequent Urination

Owners may observe changes in the frequency of their cat's urination. Frequent urination, or an abnormal increase in urination frequency compared with the cat’s normal routine, can be one sign of an underlying urinary tract issue. Many things can disrupt a cat’s routine or emotional state enough to cause this symptom, including stress, but urinary conditions remain high on the list of culprits. In particular, cats with urinary tract infections or diabetes often start urinating much more than they used to. Frequent urination can also be a sign of hyperthyroidism, kidney disease, Cushing’s disease, and more. Straining to urinate with or without passing blood is a strong sign of true urinary discomfort, but it might be hard for owners to see alone. Owners who notice an increase in the frequency that their cat pees should also watch for additional symptoms that can occur with urinary conditions and suggest them to their vet. Even without other symptoms, frequent urination should be looked into. Usually, a very prompt appointment with the veterinarian is unnecessary, but owners should try to make an appointment within the next week or so under the guidance of their veterinarian.

Owners who are concerned about their cat’s urination habits should have her checked out by a veterinarian as soon as they can. The observation of frequent urination in the clinic may alert the veterinarian to the fact that the cat’s kidneys are working overtime to remove the extra sugar produced in diabetes. To try to figure out the cause of a pee increase, the veterinarian will ask the cat’s owner about what they’ve observed their cat doing at home—how often she pees, how much urine comes out, what it looks like, if the peeing cat spends a lot of time straining in the litter box, if the owner has found urine spots outside the litter box, and more. More observations may mean that the cause is infections, urinary stones, or urine crystals, or other urinary tract problems.

5. Diagnosis and Treatment

Though unsatisfactory, often no specific cause can be determined despite the best veterinary care and thorough diagnostic evaluation of cats that present with the chief complaint of blood in their urine. Managing these cases as lower urinary tract disease (LUTD) remains the plan with relief of clinical signs and prevention of complications as the primary goals. They continue to require care and necessary diagnostics to rule out underlying conditions such as hyperthyroidism, diabetes mellitus, and chronic kidney disease. Cats with bloody urine or hematuria are typically seen by their veterinarian. A thorough history helps to identify possible causes of hematuria. The clinical signs a cat displays may help determine how quickly they should be seen by a veterinarian. Diagnosis and treatment: A complete physical exam, including blood pressure, helps identify the underlying cause of hematuria. Diagnostic tests for cats with hematuria may include a urine sample or tests on blood. Tests available to diagnose or identify causes of hematuria include urinalysis, urine culture, imaging tests such as ultrasound of the kidneys or bladder, contrast radiographs or intravenous pyelography, imaging a dye stent to your bladder, or contrast CT/x-rays and cystoscopy. The treatment for hematuria depends on the underlying cause. Hematuria due to anatomic abnormalities may require long-term medical management, minimally invasive procedures, or surgery. Hematuria caused by greater systemic disease may be severe and benefit from supportive care and medications. Any pet with unexplained hematuria should be seen by a veterinarian for a diagnosis and treatment plan.

5.1. Diagnostic Tests

Earlier we discussed the clinical signs of lower urinary tract conditions: blood in the urine, difficulty in urinating, and frequent passage of urine. While these can provide a lot of information about what could be going on, diagnosing the specific cause of the problem in cats can be more difficult, as many of the conditions in the lower urinary tract share the same clinical signs. Diagnosing is not always straightforward, and your veterinarian may discuss the possibility of a number of tests to determine the underlying cause and create a treatment strategy. So what are the common diagnostic tests and why might your veterinarian recommend them?

The first test your veterinarian may recommend is a urinalysis. This is a very helpful test for evaluating the urine and determining whether there is any inflammation or infection in the urinary tract, as well as calculating kidney function. Urinalysis can also confirm the presence of blood in the urine, which will help to diagnose inflammation in the bladder and urinary tract. It can also give your veterinarian the urine specific gravity, or density, tell them the pH of the urine, measure the amount of protein in the urine, and allow them to look for crystals in the urine. Blood tests may also be recommended, such as a complete blood count and a biochemistry panel. These are important for understanding the physical status of a cat and the functioning of other organs in the body. Urinary conditions can also have consequences elsewhere in the body, and these tests can help determine if your cat is at risk of suffering from these potential conditions. Your veterinarian may also request imaging, such as an abdominal ultrasound as well as an X-ray, to look for stones or abnormalities in the urinary tract. These tests are also helpful for understanding the overall health of the urinary tract and how it has been functioning. Some cats may be carried out under anesthesia if they are not used to being held or handled and can be particularly nervous at the clinic, to reduce any additional pressure while conducting tests. This may help get more accurate readings depending on these kinds of diagnostic measures. While it can sometimes seem overwhelming to discuss diagnostic options with your veterinarian, having a full perspective on these testing options can help pet owners engage more attentively in a dialogue. Correct identification and a comprehensive understanding of underlying lower urinary tract conditions facilitate the design of an effective treatment plan

This section addresses diagnostic procedures a veterinarian might use to investigate the cause of hematuria in a cat. In many cases of hematuria, the cause may be most easily identified with more than one of these procedures. Together, the evaluation of a cat with hematuria is necessary for an accurate diagnosis and effective treatment. One of the most useful tests that may point to the underlying cause of blood in a cat's urine is the urinalysis. This is a board of terms because not all of the components are always included in every report. In general, a urinalysis assesses the physical properties of the urine sample, the chemicals that are present, and the sediment, the solid particles that have to be centrifuged down to the bottom of the collection tube.

The biopsy procedure is relatively non-invasive if the veterinarian cannot require any significant enlargement or misshaping of the organ prior to the collection of tissue, usually via endoscopic biopsy. In these cases, a fine-needle biopsy of non-inflamed tissue can usually be performed to provide a definitive diagnosis. Ultrasound examination is often the next best recommendation in this situation. This is a non-invasive diagnostic procedure available at many veterinary facilities. An ultrasound is best at visualizing those structures located internally within the body, such as all of the components of the urinary tract. In the abdominal view, the bladder, kidneys, or other structures can be directly visualized, and any masses or hernias will be detected. An ultrasound examination is also useful to assess the size of these structures, as the kidney stones can cause an increase in kidney size.

5.2. Urinalysis

Urinalysis is the primary diagnostic tool for reactivity to red blood cells in the urine (hematuria). It evaluates various parameters to gain a greater understanding of the patient's urinary tract health: specific gravity, pH, protein, and cells and casts in the sediment among other factors. The urine sediment can indicate inflammation or injury, but multiple other factors need to be considered due to their presence in both non-inflamed kidneys and inflamed kidneys. Cells that may be present include erythrocytes, leukocytes, transitional epithelial cells, and renal epithelial cells. All of these elements can point to different causes of hematuria or may not be clinically significant, but they may also indicate active bleeding or an inflammatory disease.

There are two methods for conducting a urinalysis: an in-house test and an outside laboratory. The in-house test allows the veterinarian to conduct a test and get a result in about 10 minutes. The main diagnostic ability of a clinic is to evaluate the urine sediment, and that cannot be done on a patient unless it has a centrifuge. Outside laboratories run multiple tests on an instrument, but sediment quality is not as good as an in-house sample. For an owner, having access to a faster working clinic may be beneficial. However, the diagnostic capabilities and full results are only obtained from the fully processed sample at an outside laboratory. Unfortunately, the urinalysis is not sensitive to capturing all the different potential causes of diseases in all cases. For the cat, it may not capture all the types of stones that can form due to the mineral combinations in meat. Nor will it tell you about cats that are presenting instead with functional kidney changes. However, a hallmark of end-stage kidney disease in a cat is hyposthenuria.

5.3. Ultrasound Imaging

Ultrasound is a non-invasive and critical part of evaluating the entire urinary tract system in many cats. It is helpful for the diagnosis or the exclusion of many urinary tract conditions. Ultrasound utilizes sound waves to produce images of the internal organs of the animal and gives a direct view to the veterinarian of the cat's internal organs. While x-rays give a shadowy image of dense structures like stones, ultrasound shows shapes, sizes, texture, and "feel" of the soft tissue structures. The organ's location and relationships to one another are visualized with real-time movement of the body's internal structures. Ultrasound viewing is just like conventional photography; if the cat moves during gentle pressure of the ultrasound head, the picture remains clear. On the other hand, unlike x-rays, the ultrasound does not show length measurements from the top to the bottom of the body cavity, so it is important to have a sterile measurement technique for structure sizes.

Ultrasound is very helpful for many conditions, but it is often the best diagnostic choice when masses or tumors are noted with x-rays of the urinary tract system. An ultrasound can also be used to give guidance when biopsying a mass of the bladder or manually removing stones. It is a complementary diagnostic tool and should not be thought of as competing with other radiographic techniques such as x-ray and contrast studies. Having x-rays and ultrasounds of different regions of the body or different urinary conditions gives the veterinarian an overall picture from all these images that will allow for an accurate diagnosis in many difficult cases. When ultrasound viewing alone is used for diagnosis, it is often subject to much operator judgment, and as a result, the results from different veterinarians may slightly differ, depending on their ultrasound skills. With this in mind, it is often important to have a second veterinarian evaluate an unusual ultrasound result, since an unusual shape reported by one veterinarian may not occur with another veterinarian who is also highly skilled in ultrasound viewing. In some cases, when a structure is very clear, such as a large stone seen in the bladder, evaluation of the cheaper x-ray, without ultrasound imaging, is still extremely helpful for owners. The main benefits of this imaging tool are its non-invasive nature and excellence in assessing many diseases on several soft tissues and labeled organs in "real-time." However, the abundant fallacies of this imaging modality, such as operator dependency and the virtually indiscernible images from fat overlying the body cavity, necessitate the compounding diagnostic information obtained via conventional radiography, cystocentesis, and surgical exploration.

5.4. Biopsy

Biopsy provides a definitive diagnosis when urinary tract tumors or severe abnormalities are seen on imaging or when FNA or urine cytology findings are nondiagnostic or unclear, especially in cats with the appropriate risk of having these diseases. Less commonly, a biopsy may be necessary to diagnose less severe diseases as well, such as bladder polyps in cats. There are different types of biopsy techniques, including needle aspiration using a small needle to remove samples from the bladder wall and its associated organs, as well as surgical biopsy.

Needle aspirates are usually performed when lesions are accessible, gently adherent to the body wall, and less than 2-3 cm in diameter, such as with bladder and prostate tumors. Larger and more aggressive lesions are typically better evaluated with a surgical biopsy, using a larger specimen to obtain a definitive diagnosis. Sometimes, a CT-guided biopsy procedure will be recommended to obtain a surgical biopsy, especially when lesions are deeply located, such as with urethral tumors, or when the urinary tract is filled with inflammatory debris or blood that can contaminate the microscopic analysis of biopsies. Biopsy procedures have a low risk of complications, such as bleeding or infection, particularly if performed by a skilled individual. If the decided schedule of the biopsy is a surgical one, please make sure your cat has received no food past midnight prior to the biopsy, and limit its access to water in the morning before hospital drop-off for preparation and hospitalization in the professional care of the veterinary staff. Biopsy procedures can raise the financial cost of diagnosis and also are an emotional decision for many pet owners, especially if it comes after learning that the cat has signs of tumors growing in their urinary tracts. However, sometimes they can offer enough information for the cure if the pathology determines that you are dealing with a false alarm, or a cure can be attempted, especially if the cancer does not appear to have spread to other body parts.

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