567 — Canine Bladder Stones: Diagnosis and Treatment
Canine Bladder Stones: Diagnosis and Treatment
Dr. Marty Greer, DVM joins host Laura Reeves for a deep dive on bladder stones in dogs, how to diagnose and treat them. The following information is provided by Dr. Greer.
Bladder stones are the quintessential “which came first, the chicken or the egg” question. By this, we mean that a dog can have a bladder symptoms that are caused by a bladder stone, or the bladder infection can cause bladder stones to form. Which then becomes a vicious cycle.
There are two basic types of bladder stones – the first, struvite stones associated with a bladder infection or second, any of the following other bladder stones, caused by a metabolic disturbance that causes a stone to form in the urinary tract.
How do bladder infections cause bladder stones? An undiagnosed, under-treated or recurrent bladder infection can lead to the development of struvite bladder stones. This is the most common type of bladder stone. Or another type of stone can cause irritation to the bladder which can cause a stone to form that is partly any of the types of stone below combined with a struvite stone. These form like a pearl in an oyster – the irritation of the infection or other stone type can cause a struvite coating on an existing bladder stone.
Many metabolic stones are associated with a particular breed or disease condition causing minerals to deposit in the bladder, forming stones. These metabolic stones form with long term supersaturated minerals in the urine. With time, the crystals form which develop into a bladder stone. Other factors are the pH of the urine, inhibitors and promotors of stone formation, and macrocrystalline matrix. If something like suture is in the bladder, this can also allow a stone to form.
Fortunately, most stones in the urinary tract are in the bladder itself, where they are accessible surgically. Stones in the kidney or ureter (tube from the kidney to the bladder) are not easily managed surgically or by physical removal. Stones that form in the bladder and pack together like sand in a funnel or slip from the bladder into the urethra (tube from the bladder to the outside of the body) cause urinary obstruction. This is a true medical emergency, more common in males that females due to the length and shape of the urethra, the tube from the bladder to the outside.
Males have a design flaw – their urethra is more narrow and curved, causing a greater likelihood of urinary obstruction. On the other hand, females have a design flaw, a shorter wider urethra just below the rectum that allows bacteria to ascend into the bladder, increasing the risk that a female will have a bladder infection. That infection can often lead to the formation of struvite stones.
Symptoms
Symptoms of bladder disease can be virtually non-existent to severe. The symptoms can vary:
- No signs or very subtle signs of discomfort or urinary accidents.
- Signs of blood in the urine (often not noted until there is snow on the ground or when the urine is wiped up and blood is seen on a white towel), straining to urinate, frequency of urination, inappropriate urination, +/- fever, pain, and/or urinary incontinence. Dogs are rarely “sick” with a bladder infection – they eat, drink, and act normally other than increased trips outside or urinary accidents on the floor.
- If obstructed, there will be abdominal pain, vocalizing, vomiting, dehydration, depression, heartbeat irregularities, bladder distension, in advanced cases, bladder rupture, collapse and death.
- Blood work can show elevated BUN and creatinine, kidney values if obstructed.
- Blood work may show elevated calcium if calcium oxalate stones are present.
- Blood work may show liver dysfunction in patients with urate stones.
Below is a table showing the different types of bladder stones, comparing the composition, cause, prevention and treatment options.
| Type of stone | Cause | Prevention | Treatment |
| Struvite or magnesium ammonium phosphate hexahydrate. Usually located in bladder but can be in renal pelvis. This is the most common stone in dogs at an incidence of 53%. | More common in female than male dogs, usually young dogs. Frequently multiple. Secondary to undermanaged bacterial bladder infection incl most commonly Staphylococcus spp., but less commonly seen urease-producing bacteria include Proteus spp. or Enterococcus spp. Rarely Escherichia coli, Pseudomonas spp.,
Klebsiellaspp., Corynebacterium urealyticum, or Ureaplasma/Mycoplasma spp. May have a genetic component. Breeds: American cocker spaniel |
1. Find and manage cause of recurrent bacterial bladder infection.
2. Preventive diets lower in protein, phosphorus and magnesium including: Royal Canin® Veterinary Diet Urinary SO, Hill’s Prescription Diet c/d™, Hill’s Prescription Diet w/d™, and Purina Pro Plan Veterinary Diets UR Urinary St/Ox. 3. Increased water intake 4. Weekly monitoring of urine pH and intervention if pH rises. 5. Periodic imaging for early detection of recurrence. |
1. Dissolution diet combined with appropriate long-term antibiotics. May be dissolved medically unless obstructed.
2. Acidifiers such as D,L-methionine combined with appropriate long-term antibiotics. 3. Surgical removal or Cystoscopic retrieval 4. Physical removal. |
| Calcium oxalate or calcium oxalate combined stones. Usually in the bladder but can be in the renal pelvis. 2nd most common bladder stone seen in dogs. | More common in males, middle aged.
Patients who have increased urinary excretion of calcium /or oxalate. May include Cushing’s disease, primary hyperparathyroidism, or cancer causing elevated calcium levels. Obesity. Steroid administration. Genetic predisposition. Bichon frise |
Calcium oxalate uroliths recur 8-9% after 6 months, 35-36% after one year, and approximately 50% after 3 years.
1.Diet Royal Canin® Veterinary Diet Urinary S/O Lower Urinary Tract Support, Purina Pro Plan Veterinary Diets UR Urinary St/Ox™, Hill’s Prescription Diet w/d™, and Hill’s Prescription Diet u/d™. 2.Potassium citrate orally. 3.Thiazide diuretics. 4.Vitamin B6 |
There is no known way to dissolve this stone type so must be physically removed. |
| Cystine | More common in males, young to middle aged.
Occurs secondary to cystinuria, which is caused by increased levels of cystine excreted into urine. Uncommon. Inherited mutation of SLC3A1 gene, which leads to defective amino acid transport, described in the Newfoundland, Labrador retriever, and in the cat. Missense mutation in SLC7A9 is another cause of cystinuria in the dog. Androgen-dependent cystinuria has been described in dogs. Genetic Test: DNA testing for genetic traits is available at vetGen, Penn Gen, Paw Print Genetics, DDC, Animal Genetics, and UC Davis Veterinary Genetics Laboratory in the USA, as well as Animal Genetics-UK, Laboklin, and Animal DNA Diagnostics in Europe. Breeds: American pit bull terrier |
1. Feed protein-restricted, low-sodium diet.
2. Potassium citrate to maintain alkaline urine. 3. Some patients may also require 2-MPG therapy. 4. Do not breed affected dogs, their parents, or any other offspring. 5. For breeds with androgen-dependent cystinuria, castration can help in controlling cystinuria. |
1. Low protein, low sodium, alkalizing diet: Hill’s Prescription Diet u/d™ and Royal Canin® Veterinary Diet UC Low Purine
2. Potassium citrate to alkalinize urine with a pH goal of 7.2 to 7.5 and dilute urine. 3.Physical removal. |
| Xanthine incidence 0.5 to 1% incidence of bladder stones in dogs | An uncommon type of purine urolith.
Adults 2 to 6 years of age. No sex predilection. Causes: Allopurinol administration Idiopathic, unknown |
Purine-restricted, alkalinizing, diuretic diet helps prevent xanthine recurrence including renal failure diets or ultra-low protein diets with low purine levels (Hill’s Prescription Diet u/d™ or Royal Canin® Veterinary Diet Vegetarian) may help. Add water to food to keep urine dilute. Use potassium citrate may be needed to keep urine pH alkaline. | Will not dissolve. Must be physically removed.
Stop allopurinol treatment if possible. |
| Silica incidence 0.9% of canine bladder stones | Incidence world-wide seems regional. Primarily male dogs. Usually 6 to 8 years of age.
May be genetic with German Shepherds, Labradors, Golden Retrievers and Old English Sheepdogs being over-represented. Cause unknown.
|
Monitor with urine testing and imaging to check for recurrence. May help to feed more animal protein and less vegetable protein to reduce recurrence. Feeding diets higher in animal protein and lower in plant-based proteins (such as soybean, rice, corn gluten feed, oat-based cereals) may be beneficial. Increasing water intake may help decrease silica concentration in urine. Do not allow patients to eat grasses and soils with higher silica content. | No dissolution therapy known.
Must be physically removed. |
| Calcium phosphate – incidence 1 to 2% of canine bladder stones | Brushite more common in males.
Breeds predisposed include Shih tzu Lhasa apso Miniature Schnauzer Yorkshire terrier Miniature poodle Pomeranian Bichon frise American Cocker Spaniel |
Identify and treat the underlying cause such as primary hyperparathyroidism or Cushing’s diease (hyperadrenocorticism). Keeping urine pH of 6.5-7.5 and urine dilute helps reduce risk of recurrence. Ideal preventive diet is unknown; diets aimed at preventing calcium oxalate uroliths are reasonable options. | Associated with primary hyperparathyroidism or Cushing’s disease (hyperadrenocorticism). These also may occur as part of stones that are largely composed of struvite or calcium oxalate. Associated with alkaline pH. |
| Urate incidence 5 to 8% of canine bladder stones | Either sex, usually young dogs. Uric acid and its various salts. Associated with liver disease, hepatic dysfunction, portosystemic shunts, inherited, or less commonly, caused by urinary tract infections (UTI) with urease-producing bacteria.
Genetic mutation in the SLC2A9 gene: Australian shepherd |
Frequently recurrent at rates of 33 to 50%.
Annual or biannual imaging with ultrasound or x-rays to monitor. |
1. Dietary therapy with low purine diets (eggs, dairy and vegetable protein) – may be dissolved medically unless obstructed: Hill’s Prescription Diet u/d™, Royal Canin® Veterinary Diet Canine Vegetarian, and Royal Canin® Veterinary Diet Urinary UC Low Purine.
2. Potassium citrate at 50-150 mg/kg PO q 12 hrs or sodium bicarbonate at 25-50 mg/kg PO q 12 hrs may be used. Avoid pH above 7.5 3. Allopurinol 4. Physical removal 5. Managing underlying liver disease. |
| Combination stones | Any combination of the above stones can occur. The largest % component is reported when there are several mineral components to the stone. | Based on analysis | Based on analysis |
| Dried solidified blood | Cats only |
The above table is a summary of information published on www.veterinaryinformationnetwork.com. Thanks to this author Kari Rothrock DVM.
Diagnosis
- Symptoms are noted.
- Urinalysis: crystals seen on microscopic evaluation of the urine, bacteria, white blood cells, and white blood cells seen under the microscope.
- Culture – to identify the causative bacteria.
- X-rays – seeing stones in the bladder, kidney, ureter or urethra. May require contrast x-rays.
- Ultrasound – stones or gritty material seen blocking the ultrasound beam on ultrasound. This may be described as a “snow globe”.
- Stone analysis – essential to know the cause and how to try to prevent formation of future stones.
- Cystoscopy – when an endoscope is passed into the bladder to look for stones. Removal may be achieved at this procedure.
Physical Removal of stones: there are several techniques available to remove stones from the urinary tract.
- Surgical removal – is a procedure available at most small animal veterinary clinics with basic surgical availability. If an obstruction is present, immediate surgical intervention is essential.
- Cystoscopic retrieval – requires an endoscope and special baskets to retrieve stones from the urethra and/or bladder.
- Voiding urohydropropulsion – With sedation or anesthesia, the bladder is catheterized, filled with fluids multiple times, and with pressure on the bladder, efforts to push the stones out through the urethra is attempted. This works best in small dogs with small stones.
- Extracorporeal Shock Wave Lithotripsy (ESWL) – This involves using a shock wave to a patient immersed in a water bath. Bladder stones may move too much for this to have a successful outcome so is better suited for stones in the kidney or ureter.
- Laser lithotripsy – This involves using a laser to fragment them, then the fragments are removed. This works better in female than male dogs. Small dogs and large bladder stones may not lend themselves to this treatment option.
- Retrograde Urohydropropulsion (RU) – this involves flushing stones from the urethra back into the bladder for removal. In general, the patient will require sedation or anesthesia, followed by removal of some urine to relieve the pressure on the bladder.
Other than surgical removal, the others are usually only available at larger referral centers or veterinary schools.
Dissolution – is a process by which bladder or kidney stones can be dissolved using special diets, drugs, and or antibiotics. Not all stone types will dissolve. And not all dissolvable stones will dissolve safely. If the dog has an obstruction and cannot urinate, immediate physical removal of the stones is essential as urinary obstructions are life-threatening. Not all dogs will eat the diet required to dissolve the stones. Not all owners are willing or able to administer the medications and diets necessary to dissolve the stones. Frequent monitoring of the size and location of the stone is essential to safely allow stones to dissolve. The required diets are prescription diets, and the medications are also prescription drugs. Care in selecting the correct food and medication is required, thus the reason for prescriptions from the pet’s veterinarian.
Prevention can often be successful. Again, this requires that the owner(s) of the dog take great care to provide plenty of fresh water frequently, let the dog out to urinate frequently, and administer medication and food without “cheating”. Owners may also need to check weekly urine samples to assess the urine pH for early adjustments in medication and food to prevent recurrences.
As a result, a mutual treatment plan with the pet owners and their veterinary team is essential for a successful outcome.
502 – Seizures in Dogs: Causes, Treatments and Considerations
Seizures in Dogs: Causes, Treatments and Considerations
Dr. Marty Greer joins host Laura Reeves for this month’s Veterinary Voice talking about seizures in dogs. Type of seizure, age of onset, causes and treatments are all up for discussion today.
“Seizures can be actually epilepsy, which has probably got a genetic component to it,” Greer said. “Where the dog has an epileptic tendency. Typically those are going to be seen in certain breeds of dogs and they typically happen between two and four years of age for the first seizure. If we’re seeing seizures or seizure type activity or episodes in really young dogs or dogs that are elderly, it’s probably not primarily an epileptic situation.
“If it’s a very young puppy, the first thing we look at is blood glucose. If their glucose drops because they’re not eating adequately, they don’t have enough glycogen stores in their liver, and so they’re weak or they’re sick, they’ll have a seizure type of activity. So, the first thing we do in anything that’s really young or really old, is reach for some kind of glucose. You can reach your Karo syrup, you can reach for honey. If you have caramels and the dog is capable of chewing them, that’s great. You can give sweetened condensed milk. Glucose can be absorbed right through the gums, so the dog doesn’t actually have to swallow to get the effect of bringing up their glucose.
“If you have an older dog (with seizure activity) the first thing to do is get some initial blood work. That’s easy to do. You can check calcium, you can check glucose. It’s easiest and most effective to check it very close to the time of the event. Glucose can go down for multiple reasons. I’ve seen it go down during severe pregnancy toxicosis. I’ve seen it go down because dogs have eaten xylitol, sugarless gum and candy. And I’ve seen it go down because dogs have insulinomas, which is a tumor in the pancreas. Those are functional tumors that create so much insulin that the dog’s blood glucose drops precipitously. Anytime your glucose is too low you can have a seizure. I’ve also seen it go down in Addison’s disease.
“You want to be sure that you’re comprehensive and complete on what’s going on with the dog before you jump to any conclusions. There’s always the toxins. So, xylitol we’ve talked about as a possible toxin, but there are some rat poisons and some other neurotoxins that we can see not the vitamin K type of rat poison. There’s a lot of other kind of nasty toxins that are out there that dogs can sometimes get into. Sometimes our pharmaceutical medications can cause that as well, so appetite suppressants can cause it, there are a number of different drugs on the market that can cause seizure type of activities. It’s really important that we get a good history on these drugs what they might have gotten into.
“The other thing to know is that the new class of oral flea and tick medications can cause neurologic disease tremors. That can also include seizures in seizure prone dogs. If your dog recently had a dose of that, typically within 24 hours, you need to include that too. So you need to go through the list of anything that’s possible, anything that’s the dog was given deliberately or not deliberately so that we are not missing any information that could potentially be a problem.
“Of course, in the older dog, there are structural abnormalities like brain tumors. That’s diagnosed with either CT scan or an MRI … there’s a lot of things that make dogs look like seizures, but it’s not always epilepsy. Epilepsy is a diagnosis of exclusion. Typically, we diagnose it after everything else has been ruled out.”
Listen in to the podcast for Dr. Greer’s suggestions on treatment plans and more.
And go back to Liz Hansen‘s conversation on the research in this area.
172 – Veterinary Voice: Cruciate Ligaments
AVOID EXPENSIVE, PAINFUL CRUCIATE LIGAMENT RUPTURE
Early spay/neuter is one of the primary indicators of a potential for a “blown knee” in our dogs, according to Dr. Marty Greer, DVM. The cruciate ligaments in the stifle joint of the dog serve as a hinge when working properly. When these ligaments are stretched, frayed or torn, the dog will be painful, limping, or “off” on a rear leg. Environmental factors such as overweight and lack of condition also can contribute as causal factors, Greer adds.
TRAUMA NOT ALWAYS THE CAUSE
WHILE TRAUMA HISTORICALLY HAS BEEN CONSIDERED THE PRIMARY CAUSE OF THIS SITUATION IN THE DOG, GREER SAYS SHE SEES MORE AND MORE DOGS WITH NO KNOWN INJURY SUFFERING FROM A DAMAGED JOINT.
“… THERE’S A HUGE INCREASE IN INCIDENCE OF CRUCIATE RUPTURES IN DOGS THAT ARE SPAYED AND NEUTERED WHEN THEY’RE YOUNG,” GREER SAID. “AND BECAUSE THERE’S BEEN A BIG MOVEMENT TO EARLY SPAY AND NEUTER FROM THE RESCUE ORGANIZATIONS AND THE HUMANE SOCIETIES FOR REASONS OF POPULATION CONTROL, THEY’VE PUT OUR DOGS AT INCREASED RISK. INADVERTENTLY, THEY DIDN’T SET OUT TO DO THAT, BUT INADVERTENTLY, THEY SET OUR DOGS UP FOR FAILURE IN THE DEVELOPMENT OF THEIR JOINTS. SO, WHEN A DOG IS SPAYED OR NEUTERED WHEN THEY’RE REALLY YOUNG, THEIR GROWTH PLATES STAY OPEN LONGER. WE KNOW THAT FROM LLAMA’S. WE KNOW THAT FROM HUMAN EUNOCHS … SO, IF YOU WALK DOWN THE AISLE IN A HUMANE SOCIETY AND YOU SEE A LONG LEGGED SKINNY STRAIGHT KNEED BLACK 60-POUND DOG, ODDS ARE PRETTY GOOD THAT IT’S A MALE THAT WAS NEUTERED WHEN HE WAS 3, 4, 5 WEEKS OLD, MAYBE TWO OR THREE MONTHS OLD. BUT WE DO KNOW THAT THE INCIDENCE IS MUCH, MUCH INCREASED IN DOGS THAT ARE SPAYED AND NEUTERED REALLY EARLY. SO THAT’S ONE FACTOR THAT REALLY NEEDS TO BE TAKEN INTO ACCOUNT.”
Anterior Cruciate Ligament (ACL) Rupture
Rupture of the anterior or cranial cruciate ligament is more common after gonadectomy than in intact dogs (Whitehair et al. 1993; Duval et al. 1999; Slauterbeck et al. 2004). Breeds at risk for rupture of the ACL include the Akita, American Staffordshire terrier, Chesapeake Bay retriever, German shepherd dog, golden retriever, Labrador retriever, mastiff, Neopolitan mastiff, Newfoundland, poodle, rottweiler and St. Bernard (Duval et al. 1999; Harasen 2003). Other risk factors include obesity and abnormal angulation of the stifle (Ragetly et al. 2011). One could argue that increased risk of ACL injury after gonadectomy is because of decreased athleticism and obesity in gonadectomized animals but the trend stands even in studies that statistically compensated for these effects in dogs. Joint laxity may differ under varying hormonal stimuli, suggesting one possible cause‐and‐effect mechanism. Another hypothesis is increasing stifle angulation with asymmetry of growth plate closure in the femur and tibia.
https://onlinelibrary.wiley.com/doi/full/10.1111/j.1439-0531.2012.02078.x
Tick borne diseases that can cause joint inflammation are another area Greer notes that may cause complications. Often times, a dog will not have a fully ruptured ligament, but these important sort of elastic bands in the joint will have frayed or “stretched.” Treating these dogs with crate rest, testing for tick borne diseases and treating with a prophylactic course of Doxycycline that both treats tick borne diseases and confers some anti-inflammatory process in the joint is Greer’s recommendation.
Patellar luxation is a genetic disorder that serves as complicating factor for potential injury to the knee joint as well, according to Greer.
Surgery to repair a torn cruciate ligament is expensive and requires the best orthopedic surgeon you can find, Greer said. But it isn’t an emergency situation. If you suspect a cruciate injury,
- Keep the dog quiet and crated.
- Take it to your veterinarian for diagnosis.
- Research the best surgeons available in your area.
- Be diligent about maintaining *strict* crate rest during recovery.
We hope you enjoy today’s podcast with Dr. Greer. For more information on this topic, visit:
https://www.researchgate.net/publication/312054514_Top_5_Genetic_Diseases_of_Dogs
162 – Veterinary Voice: Health Testing 101 with Dr. Marty Greer
VETERINARY VOICE: HEALTH TESTING 101 – DR. MARTY GREER
Dr. Marty Greer, DVM, JD returns to our Veterinary Voice series to talk about health testing for our breeding programs.
Using testing to improve our dogs’ overall health involves looking at both “phenotype” — diseases we can test for with xrays, blood or other physical exam — and “genotype” — those diseases identified by DNA testing.
Dr. Greer also provides some great input on the various DNA tests cropping up all around us. These tests, all spinning off from the identification of the canine genome, provide breeders, exhibitors and pet owners with a plethora of options for naming everything from the mixture of breeds in a shelter dog to the specific heritable genes for deadly diseases.
One of Greer’s primary points, which we’ll touch on again next week in our podcast with Dr. Jerold Bell, is that these health testing options provide breeders with the ability to *expand* their gene pools. Scientifically identifying a dog as a carrier and another as a non-carrier of a specific disease gene, for example, enables breeders to breed those two individuals with the assurance that none of the resulting progeny will be affected by the disease in question.
Many of our dogs are impacted by polygenic diseases, in other words something like hip dysplasia, for which there is no DNA test because it is predicated on more than one simple gene pair. Nonetheless, the future of breeding healthy dogs is made profoundly more “user friendly” with the available testing protocols for those who use them wisely.
“So, the tricky part, and I think the really hard part for people that as breeders are running these tests are for them to try and decide how to use that information in their breeding program,” Greer said. “… I see a lot of breeders who are so distraught about finding a genetic defect in their dog or in their line of dogs that they will throw out a whole line of dogs genetically. They will just stop breeding that whole line and it is narrowing and bottlenecking our gene pools even further than a lot of the breeds already are. So, we have to be really careful how we interpret and use those results.”
BREEDING DECISIONS
Greer goes on to discuss various health concerns and how those should apply to making breeding decisions.
“So, I tend to rank, personally, genetic diseases on a ranking of one, two and three, because you can’t treat them all the same,” Greer said. “So, things like an umbilical hernia, or an extra eyelash, you fix it once surgically, it is corrected. …the reality of it is those are not life-threatening diseases … Ranked two are things like allergies and thyroid disease, which require chronic medications. They always have to be on medication for those diseases if they have them. … And then ranked three are the things that are life-threatening, life-altering, life-changing diseases, and those are arthritic changes like hip dysplasia, seizures that are life-threatening, and, frankly, bad temperament in my opinion has the same categorization because some of those dogs have such bad temperaments that they bite people and that’s life-changing, life-altering and life-threatening. … I want to kind of frame it so people understand that not all not genetic diseases are the same, not all should be treated equally, and we have to really be thoughtful about how we use this information in breeding programs.”
The judicious and thoughtful use of health testing results and criteria in breeding healthy dogs presents almost a continuum of application in Greer’s experience. Potentially unhealthy dogs with no testing on one end and dogs with extensive testing but a potentially limited gene pool which may entrench diseases at the other end of the spectrum.
“…the Dandie Dinmonts, the Otterhounds, these people with small gene pools can serve as models for other breeds,” Greer said, “because even Labradors and Golden Retrievers are narrowed pools compared to what we have seen in the past. So, absolutely we need to be looking at these kinds of opportunities to perpetuate our genetics and not breed ourselves into such a bad corner that we end up with everything having a genetic disorder that is insurmountable, because some of these diseases are pretty serious and they become very ubiquitous in a breed.”