Why seek a member of the ASVNU to help care for your pet?
Managing Kidney and urinary disease can be difficult...
Dogs and cats commonly develop various abnormalities within the kidneys and urinary tract. Some conditions may be acutely life threatening and others may be chronic, yet still affect your pet's quality of life. Members of the ASVNU have clinical and research interest in the diagnosis and management of these diseases. Many have authored research papers that have increased the profession's understanding, and others are consider leaders in the field. ASVNU members have gone above and beyond standard veterinary training to obtain experience and expertise in the management of kidney and urinary conditions.
ASVNU members often can perform diagnostics and provide therapeutics that many other primary care and specialist veterinarians cannot. Such diagnostic tools include kidney biopsy, glomerular filtration rate testing, urethral pressure profiling, ultrasound, cystoscopy, fluoroscopy, and blood pressure measurement. Treatments can include hemodialysis, therapeutic plasma exchange, ureteral and urethral stenting, ectopic ureteral laser ablation, urethral bulking, subcutaneous ureteral bypass (SUB) placement, renal transplantation, and more. ASVNU members may be able to offer some of the most advanced health care options for your pet.
CLICK HERE to find the nearest ASVNU member.
Client Educational Information
The most common indication for hemodialysis in our patients is acute kidney injury. Patients
refractory to medical therapy, as well as oligoanuric patients are candidates for hemodialysis. Hypervolemia, acidemia, and electrolyte disturbances, such as hyperkalemia, can quickly and effectively be managed with hemodialysis. Chronic kidney disease can also be managed with ongoing hemodialysis.
The duration of dialysis therapy is quite variable. Many toxicities (such as ethylene glycol, NSAID
ingestion, etc) can be treated with a single treatment. Oligoanuric patients with acute kidney injury may require as few as 1-3 treatments until they become polyuric, thus often allowing the reintroduction of traditional management. Patients with severe kidney injury may require weeks to
months to regain kidney function. Dialysis is initially performed on an inpatient basis; however patients are transitioned to outpatient dialysis when stable.
During dialysis, your pet is awake and relaxes on comfortable bedding. They can eat, sleep, and receive medications during dialysis. There is no pain associated with dialysis procedures. Because the blood is being removed from a venous catheter, there aren't even any needles involved! Patients typically enjoy the attention they receive during their 4-5 hour dialysis treatment and often feel spoiled!
Hemoperfusion involves passing blood through activated carbon or other polymers to remove large toxins that cannot pass through the dialysis membrane. This is a useful way to remove numerous toxins that pets may be accidentally exposed to. Drugs like NSAIDs (human and veterinary), chemotherapy drugs, anti-seizure meds, and other human medications have been commonly removed via hemoperfusion from animals who have ingested them, often preventing organ dysfunction and death. Poison Control Centers often do not realize dialysis can help in the treatment of a toxicity. Dialysis treatment prior to organ dysfunction gives patients the best possible outcome. Please don’t hesitate to call your local ASVNU member to discuss if dialysis is right for your pet.
Bay’s (a 4 year old Lab mix) owners returned home from a day out to find her unconscious, having difficulty breathing, and not responding. She had eaten half a bottle of ibuprofen sometime during the day. When Bay was presented at Friendship, she was unconscious due to the effects of ibuprofen. Hemodialysis and hemoperfusion allow us to remove toxins from the blood in ways that traditional therapies cannot. If treated early enough, drugs (like ibuprofen) can be removed from the blood prior to causing any permanent organ damage. Two hours into her treatment, Bay woke up and became neurologically appropriate! She walked back to her cage after the 5 hour treatment and was discharged from the hospital 2 days later with no kidney or liver injury! She still remains normal a year later!
My vet recommended a cystoscopy, what are the benefits?
Physical exam, xrays and ultrasound are good indirect ways of knowing facts about the kidneys, bladder, prostate (in males) and urethra such as whether there is thickening or a mass present, whether stones are present, where the bladder is sitting within the cat or dog, and possibly whether there are anatomical abnormalities present in the ureters (but xray with contrast, ultrasound and even CT are not necessarily accurate when it comes to finding ureters in the wrong place). X-rays, ultrasound and CT are not very good at evaluating the urethra, the ureteral openings, ducts coming from the prostate (in males), the vaginal vault and vestibule (in females), and the surface of the bladder. Because of the concern for spreading cancer from the bladder to the rest of the abdomen or the abdominal wall, image-guided sampling of the bladder is not routinely performed. Cystoscopy allows for evaluation of:
- Vaginal septal remnants (can contribute to UTIs)
- Vaginal discharge or masses
Vestibule (space in front of vagina)
- Masses (can be sampled by biopsy)
- Anatomical abnormalities (such as ectopic ureter openings)
- Poor conformation
- Stricture (scar banding which might prevent stones from passing or create straining to urinate)
- Masses or thickening
- Stones (which may be able to be removed at the procedure or broken down with lasers)
- Anatomical abnormalities (such as ectopic ureter openings)
- Inflammation (access allows sampling by biopsy)
- Infection (access allows sampling by biopsy)
- Masses (can be sampled by biopsy)
- Polyps (can be sampled by biopsy)
- Anatomical abnormalities (ectopic ureters, defects in the bladder wall)
- Ureteral openings (cystoscopy allows for evaluation and access)
- Flexible cystoscopy (limited centers)- evaluation of ureter and renal pelvis
Most importantly, cystoscopy is a minimally invasive non-surgical approach to evaluating the urinary tract and surrounding structures. In many cases it is an outpatient procedure, although in some cases urethral swelling or spasm after the procedure may make it necessary for patients to stay overnight in hospital to make sure that they can urinate appropriately at home.
Lithotripsy consists of multiple different techniques including those performed outside the body (extracorporeal lithotripsy) and those performed within the body (intracorporeal lithotripsy). Extracorporeal shockwave lithotripsy is performed primarily for kidney stones that are non-responsive to dissolution management, partially or fully obstructive or contributing to recurrence of urinary tract infections. This is performed only at several specialized centers in the world and requires video X-ray guidance and shockwave equipment as well as the expertise to provide appropriate case selection for this procedure. Extracorporeal shockwave lithotripsy cannot be performed in cats. In dogs, there are minimal side effects, however ureteral obstruction, pancreatitis and blood in the urine can occur after treatment. Seldom can centers arrange for this therapy on a same day basis and cases will require planning and coordination between multiple clinicians. Intracorporeal lithotripsy (within the body) can be performed inside the kidney using a surgical or through the skin approach to access the stones through an incision and developed channel in the kidney. Breaking down the stones can be performed with a laser or ultrasonic probe and then the stone fragments can be removed. In the lower urinary tract (bladder, urethra), obstructed stones, or stones too big to pass can be broken down using laser pulses during a video endoscopy guided procedure and then removed from the urinary tract with a special endoscopic retrieval tool. Laser lithotripsy is limited by patient stability under anesthesia, number of stones and the difficulty in breaking down a large number of stones at a time. Your urology team will help to decide whether this approach or a standard surgical approach is more appropriate. More recently, access to the ureters has opened the potential of laser breakdown and retrieval of stones in the kidney and ureter by passing a flexible scope up the ureter to remove stones.
Urethral collagen injection
Collagen injection is performed typically in addition to medical therapy in dogs with urinary incontinence due to urethral sphincter mechanism incompetence or in dogs with congenitally wide urethras. Collagen injection is seldom considered an initial therapy, and is usually discussed once medical options have been exhausted to treat urinary incontinence. The procedure involves the injection of collagen under the surface of the urethra just after the neck of the bladder at several sites with video guidance from an endoscope. The collagen type can be variable based upon market availability and the result is a substantial improvement in continence for approximately 10 months. Seldom does procedure provide total continence, but it can make a significant difference when combined with medical therapy. When the injection site areas are no longer improving continence the procedure may be able to be repeated either by augmenting previous injection sites or creating new ones. One of the underlying considerations of performing this procedure is the age of the animal. When dealing with a very young incontinent dog, other more permanent options such as placement of a hydraulic occluder may be worthy of consideration. Ask your urology team about the availability and suitability of collagen injection for your canine companion.
For animals with recurrent stones, your internist may recommend having voiding urohydropropulsion performed if the stones are small enough. Voiding urohydropropulsion is a procedure in which the patient is anesthetized and the bladder is filled with saline, typically by placing an endoscope into the bladder, visualizing the stones, and then filling the bladder through the endoscope. The patient is then placed in an upright position and the bladder is moved back and forth to shake the stones down into the urethra while an assistant holds off the urethra to prevent fluid from leaking out. The assistant is then directed to let go and the bladder is manually emptied (expressed) while holding a pan under the dog. The clinician can then count the number of stones present and submit stones for testing to help direct future therapy. This process is repeated until stones can no longer be seen either on endoscopic examination or on post-procedure xrays.
Renal sclerotherapy is performed for patients with idiopathic renal hematuria, a condition in which the kidney is bleeding likely due to a compromised blood vessel that is in contact with the renal pelvis (the area of the kidney where the urinary tract begins). Patients referred for sclerotherapy will usually have had other potential reasons for blood in the urine completely ruled out (e.g. stones, urinary tract infection, masses, significant inflammation, ulcerative cystitis, urethral bleeding). During this procedure, the patient is anesthetized and cystoscopy is performed to identify the ureteral openings. The endoscopist will first identify which side the bleeding is coming from by watching the jets of urine coming down from the kidneys. If no blood in the urine is noted, then the procedure cannot be performed, because bleeding events are usually sporadic and may resolve on their own unexpectedly. Once the bleeding side is identified (rarely it may be both sides), the endoscopist gets access to the ureter by placing a wire into the ureter followed by a catheter that goes over the wire up to the base of the kidney. A contrast study will then be performed to evaluate the outline of the renal pelvis to determine if there is a blood clot or mass present. The catheter is then exchanged using wires for a balloon catheter that helps to seal off the renal pelvis at the junction between the renal pelvis and the ureter. Iodine is injected into the renal pelvis and the distension of the kidney is observed on video xray (fluoroscopy). The clinician will use this opportunity to measure the fluid capacity of the renal pelvis. Typically this iodine solution is infused twice into the renal pelvis to insure that the balloon catheter is preventing leakage of fluid into the ureter. The iodine has two purposes, it provides a contrast study and it also provides some degree of chemical cauterization of the bleeding vessel. In one study, only iodine was infused into the renal pelvis and there was clinical success in eliminating macrohematuria (or obvious bleeding). Once the iodine dwells (typically 5 minutes of waiting with iodine in the renal pelvis) have been repeated twice, silver nitrate (a strong chemical cauterization agent) is injected to the pre-determined volume into the renal pelvis. This is then allowed to sit for twenty minutes prior to letting it drain out. This process is repeated 1-2 times or until no pink discoloration can be seen in the fluid draining from the catheter. After the procedure the patient may continue to pass pink urine and blood clots for the next 1-3 days. The patient should be monitored in hospital overnight to determine that the kidneys do not become obstructed. Recheck of the urine and kidney ultrasound may be performed within 2-4 weeks post-procedure. In about 40% of cases the other kidney may subsequently develop renal hematuria, necessitating either monitoring for anemia or an additional procedure. Occasionally, patients may need to have a repeat procedure performed on the same side that was treated previously.
Subcutaneous ureteral bypass (SUB)
The subcutaneous ureteral bypass is recommended in cats with ureteral obstruction due to stones, stricture or unknown cause. It is also performed as a salvage procedure for patients with bladder or urethral cancer that is compromising urine flow from the kidneys to the bladder. This procedure is preferred over ureteral stenting in most cases due to the difficult path that the wire must traverse through the narrow feline ureter. The subcutaneous ureteral bypass is a relative newcomer to the field of interventional urology, as the procedure went through its last iteration of improvements in 2014. During the procedure the kidney is accessed and isolated at open abdominal surgery. The kidney is then accessed under video x-ray (fluoroscopy) guidance and a nephrostomy tube (a pigtail catheter) is guided into the base of the kidney (renal pelvis) and then locked into place with a loop and on the exterior with a cuff that is glued and sutured to the renal capsule. The seal is then leak tested until no contrast can be seen escaping the the path of the catheter out into the abdomen. The other end of the nephrostomy tube is then passed through the body wall, clamped and set aside temporarily. Next, apex of the bladder is accessed either with a sharp point or through an over the needle catheter with wire and a cystostomy tube is placed into the bladder and glued in place to the exterior of the bladder. This is then leak checked with fluoroscopy. The other end of the cystostomy tube is then passed through the bladder wall at a pre-measured point. Next, the nephrostomy tube is connected to a round metal port with a hollow channel that has a silicone hub that will be able to be accessed through the skin. The tube is glued onto the port and then a rubber combing is pulled over the connection and also glued in place. The same step is repeated on the cystostomy tube side. The system is then leak checked under fluoroscopy prior to being sutured into place on the body wall. The skin is then closed such that the port does not sit near the suture line. At the end of the procedure urine will flow from the kidney, through the nephrostomy tube to the port and then through the port to the bladder.
Patients with the subcutaneous ureteral bypass system (SUB) will have kidney values typically rechecked 2 weeks post procedure and will have a chemistry panel, urinalysis and urine culture checked at one month post procedure. To access the port, veterinarians need to have a non-cutting needle in stock called a Huber needle or owners need to bring this with them. Every SUB system pack for surgery comes with two Huber needles and typically these are sent home with the owner for emergency or routine sampling reasons. Every 2-4 months depending on the institution and patient, the SUB system must be flushed with saline bubble contrast under ultrasound guidance to insure that there is fluid flow into the base of the kidney and into the bladder. During this procedure the system and port will also be inspected for irregularities should the need arise, and contrast imaging can be performed if the SUB fails to flush normally. Owners should be aware that the SUB system does carry a risk of complication in addition to the commitment to lifetime screening of chemistry panels, urinalysis, periodic culture and flushing. Patients may experience implant related complications including obstruction of the system due to mineralization, kinking, blood, pus or tissue. There is also a risk that infection can be introduced during flushes (which are mandatory to maintain flow), or that patients with chronic urinary tract infection could continue to experience infection. Some institutions will perform a ureterotomy to remove stones from the ureter in hopes of restoring flow and removing possible areas for re-infection but not every institution takes this step. Other complications include failure of connections of the system and leakage of urine into the abdomen. Rarely, patients may experience the urge to urinate (dysuria) when the end of the tube in their bladder touches the far wall. In some instances blockage or loss of mechanical integrity of the SUB system may necessitate a repeat surgery which may or may not be possible depending upon the original condition of the kidney. Large scale studies of randomized head to head outcomes of SUB placement vs. ureteral stenting vs. ureterotomy (ureteral surgery) has not been performed, largely due to the logistics of coordinating such an effort. Recent developments in this area include a study that has been presented in abstract form that shows that 50% of patients re-establish flow down the obstructed ureter in the time following SUB surgery. How this will impact the permanence of placement or future design is unclear. Additionally, studies have been published with non-image guided placement of SUB systems which may impact the rate of placement in private practice (although this study involved less than 20 cats). A recent study has also been published which showed equivalent outcomes between ureteral surgery and ureterotomy. Given that the SUB system was created in part to improve outcome over ureteral stenting there may be some cases in which ureterotomy is ultimately relied upon again. Important considerations for any patient undergoing interventional procedures are the extent of previous renal damage from chronic kidney disease, the fragility of the kidney into which the stent is placed, the underlying cause if it can be determined, the history of urinary tract infections and most importantly the owner understanding of commitment and willingness to work through complications as they arise. As with dialysis, early intervention for better outcome is key. Longterm medical management of obstruction may prolong damage and prevent optimal outcomes. Ureterotomy carries a 40% re-occurence of obstruction, so this must be weighed in any consideration. As more centers perform the SUB procedure the outlook will become clearer.
In certain conditions involving rapid protein loss in the urine, acute kidney injury with protein loss in the urine, or protein loss in the urine that is resistant to standard medications, your internist may recommend a kidney biopsy. Kidney biopsies can be performed under ultrasound guidance with a core biopsy needle in some cases, and in other cases may be performed either with a core biopsy needle or wedge biopsy at an open surgical procedure. It is important that this procedure be performed at a facility that has a prepackaged renal biopsy kit with appropriate preservation reagents to perform light microscopy, electron microscopy and immunofluorescent microscopy as these three evaluation types are needed to fully evaluate the kidneys. According to the American College of Veterinary Internal Medicine 2013 consensus statement on glomerular disease, diseases of protein loss fall into three major categories- amyloidosis (a disease of abnormal protein deposition within the kidney which can rapidly or slowly lead to decline in function), immune-mediated disease (which can be treated and lead to improvement in some cases) and all other disease classes some of which may respond to immunosuppression regardless of whether an immune-mediated cause is known or not. Diseases of protein loss can run within families of dogs, can be congenital (or inborn errors), can be immune-mediated, infectious, toxin related or other acquired conditions. The opinion is shifting towards early biopsy in many cases because some forms of protein loss from the kidneys can be readily treated. For owners, costs to consider are the cost of ultrasound guided or surgical biopsy at your facility plus the cost of having the sample evaluated by a renal pathology service. Hemorrhage and possible minor decline in kidney function can be noted, and there is the possibility of sympathetic nervous stimulation whenever the kidneys are manipulated. During the biopsy procedure, your internist will evaluate samples to make sure that there are enough of the filtering units of the kidney present to diagnose the condition in question. Please keep in mind that there is a condition called minimal change disease which is rare, but few changes do not necessarily indicate a lack of disease. Post-procedure care include recheck fast ultrasound to screen for hemorrhage.