Functional Urinary Retention in Dogs

 

Urinary retention is the medical term given to incomplete emptying (or voiding) of urine that is not associated with obstruction of the urinary tract, whereas “functional” is defined as being caused by a problem with the normal action of an organ.

 

Complications resulting from functional urinary retention may come from a lower urinary tract infection that ascends into the bladder; rupture of the urinary bladder or urethra; and permanent injury and atony (weakness/loss of coordination) to the detrusor muscle, the muscular layer of the urinary bladder wall, which contracts, pushes down on the contents of the bladder, and causes the urine to leave the body through the urethra.

 

This condition is more common in male than in female dogs.

 

Symptoms and Types

 

• Palpably distended urinary bladder
• Ineffective, frequent, attempts to urinate without success
• Urine stream may be weak, attenuated, or interrupted
• Bladder may be so full that it frequently leaks urine
• Abdominal distension, abdominal pain, or signs of postrenal azotemia may predominate in rare cases or with urinary tract rupture
• Recurrent urinary tract infections may have caused muscular problems associated with urinating

 

Causes

 

Hypercontractility of the Urinary Bladder Detrusor Muscle (Detrusor Atony)

 

• Most commonly develops after sudden (acute) or long-term (chronic) urinary bladder overdistension; many dogs have a history of nervous system dysfunction or previous urinary blockage or obstruction
• Electrolyte disturbances such as hyperkalemia, hypokalemia, hypercalcemia, hypocalcemia
• Lesions of the pelvic nerves
• Lesions of the sacral spinal cord (such as congenital malformations, cauda equina compression, lumbosacral disk disease, and vertebral fractures/dislocations) can result in a flaccid, overdistended urinary bladder with weak outlet resistance (outlet resistance is inhibition of the ability to pass urine through the urethra)
• Lesions of the suprasacral spinal cord (such as intervertebral disk protrusion, spinal fractures, and compressive tumors) can result in a distended, firm urinary bladder that is difficult to express or empty by gentle manual pressure
• Dogs with neuropathy, sacral lesions, suprasacral spinal lesions, or midbrain disorders may also suffer from detrusor-urethral dyssynergia, where the contraction of the detrusor muscle and the relaxation of the urethra are not coordinated
• Decreased contraction of the detrusor muscle (detrusor atony) with urine retention is a feature of a disorder characterized by abnormal function of the autonomic nervous system (known as dysautonomia); dysautonomia has been described in dogs in certain geographic regions of the United States
• Some dogs with excessive levels of steroids produced by the adrenal glands (known as Cushing’s disease) have increased urination (polyuria), urinary bladder distention, and mild urine retention

 

Functional Urinary Obstruction

 

• Previous pelvic or urethral surgery
• Anticholinergic medications (which may affect normal nerve actions)
• Excessive urethral resistance, usually attributed to smooth or striated muscular components of the urethra (urethrospasm) may be seen after urethral obstruction or urethral or pelvic surgery, urethral inflammation, or prostatic disease

 

Diagnosis

 

You will need to give a thorough history of your dog’s health, onset of symptoms, and possible incidents that might have led to this condition. A complete blood profile will be conducted, including a chemical blood profile, a complete blood count, and a urinalysis. The urinalysis may reveal evidence of urinary tract infection or inflammation.

 

A neurologic examination will include a brief assessment of the lower, caudal spine. Peripheral nerve function will be apparent from the examination of anal tone, tail tone, and perineal reflexes (the muscle between the anal and urethral openings). Urethral catheterization may be required to rule out urethral obstruction. If there is no obstruction the catheter should pass easily through the urethra.

 

Myelography, epidurography, or computed tomography (CT scans) can be used to determine if lesions are present on the spine, indicating a neurological cause. Another imaging technique veterinarians use involves injecting a radiocontrasting agent into the dog’s body to follow the course of the urine from the kidneys through the urethral tract by X-ray.

 

Because there are several possible causes for this condition, your veterinarian will most likely use differential diagnosis to settle on the underlying cause. This process is guided by deeper inspection of the apparent outward symptoms, ruling out each of the more common causes until the correct disorder is settled upon and can be treated appropriately.

 

Here are some of the possible causes that will be considered and either discounted or confirmed:

 

• Extramural urethral compression, such as smooth bladder neck mass, a large prostate gland, or a caudal abdominal mass
• Oliguria, anuria, and urinary tract rupture
• Physical and mechanical obstruction; clinical signs of urinary obstruction include pollakiuria, stranguria, and hematuria; patients with mechanical obstruction may void a few drops of urine after long periods of straining
• Lesions above the spine or on the sacrum (the posterior base of the spine) that can affect signals from the brain and consequently the impulse to urinate; may also be indicated by partial or complete paralysis of limbs, hyperreflexia of limbs, and cervical, thoracolumbar, and lumbar pain; depressed tail tone;
• The urinary bladder is usually distended, firm, and difficult to express with lesions of the upper spine, and is typically distended, flaccid, and fairly easy to express with sacral lesions; in patients with chronic or partial lesions, reflexive voiding may return
• Loss of muscle coordination in the detrusor muscle
• In patients recovering from urinary obstruction, inability to void may result from re-obstruction, excessive urethral resistance (functional obstruction), or detrusor weakness (atony) caused by overdistension; if the urinary bladder can be expressed via gentle manual compression applied on the abdomen, detrusor atony is likely; if resistance to manual expression is encountered and urethral obstruction can be ruled out by examination or catheterization, functional obstruction is likely

 

Pelvic Bladder in Dogs

 

The term “pelvic bladder” involves displacement of the bladder from its normal position and affected size and/or position of the urethra. This condition is usually seen in young intact female dogs with urination problems but some dogs with pelvic bladder don’t show urination problems.

 

This condition is more common in dogs than cats presumably due to shorter size of urethra in dogs. In addition, it may occur in dogs of both sexes, either intact or neutered, although it is more common common in intact females less than year of age. In male dogs, it is usually detected after neutering.

 

Symptoms and Types

 

Some dogs may not exhibit any symptoms, while in others the following may be seen:

 

• Involuntary urine passing (urinary incontinence)
• Inability to urinate more than a few dribbles at a time
• Urgency to urinate without ability to pass urine
• Urine scalding of tail and adjacent area

 

Causes

 

Displacement of bladder from its normal position may be due to a congenital defect (birth defect). It is also thought to be caused by obesity in some dogs, and is generally associated with urologic abnormalities, aside from the obvious incontinence.

 

Diagnosis

 

You will need to give a thorough history of your dog’s health, including background history of symptoms. After taking a complete history, your pet’s veterinarian will conduct a complete physical examination. Laboratory tests including complete blood count (CBC), biochemistry profile, and urinalysis will be conducted. If infection is suspected, your veterinarian will take the urine sample and will send it to a laboratory to culture and hopefully identify the causative organism. Urinalysis, meanwhile, may reveal urinary tract infection like presence of pus, blood, bacteria in urine.

 

Other diagnostic procedures include abdominal X-rays and contrast cystourethrography. Radiographic examination of the urethra and urinary bladder after introduction of contrast medium may reveal a short, widened, or irregularly shaped urethra. Your veterinarian may also perform an ultrasound to examine kidneys and urinary bladder for stones, masses, distention of kidneys, and other abnormalities related to urinary system.

 

 

Vesicourachal Diverticula in Dogs

 

Vesicourachal diverticula is congenital condition in which the urachus — embryological canal or tube connecting the placenta with urinary bladder of fetus — fails to close. This impairs the animal’s normal urine outflow and makes it susceptible to urinary tract infections. If not treated properly, the condition may persist indefinitely.

 

Symptoms and Types

 

 

Causes

 

Often, vesicouracahal deiverticula occurs in the womb or during the birthing process. However, there is also an acquired form of the condition, which results from diseases that put undue pressure on the bladder (e.g., bacterial urinary tract infections, uroliths, and urethral plugs). There is no breed or age predisposition for vesicouracahal deiverticula.

 

Diagnosis

 

You will need to give a thorough history of your dog’s health, including the onset and nature of the symptoms. The veterinarian will then conduct a complete physical examination, as well as a biochemistry profile, urinalysis, and complete blood count (CBC) — the results of which help identify the underlying cause of the condition and the present of concurrent disorders.

 

The best tool for confirming diagnosis, however, is X-rays of the urethra and bladder while using contrast medium.

 

Perirenal Pseudocysts in Dogs

 

A perirenal pseudocyst is a capsule of accumulated fluid around the kidney that causes it to enlarge. However, it is not technically a cyst because it lacks a true membrane covering. This condition is rarely seen in dogs and may affect one or both kidneys.

 

Symptoms and Types

 

Although most dogs with a perirenal pseudocyst have a nonpainful, enlarged abdomen, some may not display any symptoms (asymptomatic). In severe cases, symptoms of renal failure may manifest.

 

Cause

 

Although the exact cause of a perirenal pseudocyst is not completely understood, kidney tumors, surgeries involving the kidney, and certain types of injuries are thought to be factors for developing the capsule.

 

Diagnosis

 

You will need to give a thorough history of your dog’s health, including the onset and nature of the symptoms, to your veterinarian. He or she will then perform a complete physical examination, as well a biochemistry profile, urinalysis, and complete blood count (CBC) — the results of which are normal unless severe renal insufficiency is present.

 

Imaging studies, including X-rays and ultrasounds, may identify which kidney is affected. Additionally, a fluid sample from around the affected kidney may be taken for further evaluation.

 

 

Xanthine Urolithiasis in Dogs

 

Xanthine is a naturally occurring by-product of purine metabolism. It is normally converted to uric acid (the waste product of proteins found in the blood) by the enzyme xanthine oxidase and passed out of the body via urine, but because xanthine is the least soluble of the purines excreted into the urine, excessive amounts of xanthines may be associated with formation of xanthine uroliths (stones). Impairment of xanthine oxidase ultimately results in xanthines in the blood (hyperxanthinemia) and xanthines spilling over into the urine (xanthinuria). It may be naturally occurring, as with enzyme deficiency, or drug-induced (allopurinol). Xanthinuria can be a congenital or an acquired disease.

 

In naturally occurring xanthinuria, a familial or congenital defect in xanthine oxidase activity is likely. In Cavalier King Charles spaniels, an autosomal (non-sex-linked) recessive mode of inheritance has been supposed to occur.

 

Acquired xanthinuria is a common complication in dogs that are being treated with the drug allopurinol for urate urinary tract stones or leishmaniasis (a parasitic infestation). Consumption of high purine diets (high protein) also increases the risk of xanthinuria in patients that are being treated with allopurinol.

 

Symptoms and Types

 

• May be asymptomatic
• Mustard colored urine
• Bladder stones:
• Stones in the urethra:
  • Frequent urination
  • Difficulty urinating
  • Bloody urine
  • Urethra may be blocked
• Kidney stones (nephroliths):
  • Asymptomatic
  • Hydronephrosis – kidney is swollen with urine due to a blocked ureter (the tube leading to the bladder from the kidney)
  • Kidney disease

 

Causes

 

• Xanthines in the urine can lead to formation of stones
• Genetic predisposition in Cavalier King Charles spaniels
• Excessive allopurinol medication in combination with high purine diet
• Relation to urine chemistry:
  • Acid urine pH
  • Highly concentrated urine
  • Incomplete and infrequent urination

 

Diagnosis

 

Your veterinarian will perform a thorough physical exam on your dog, taking into account the background history of symptoms and possible prior conditions that might have led to this condition. A complete blood profile will be conducted, including a chemical blood profile, a complete blood count, a urinalysis and an electrolyte panel. The urinalysis will show xanthine crystals in the urine sediment.

 

These crystals cannot be distinguished by light microscopy alone. For a precise diagnosis, the urine should be sent for infrared spectroscopy, which can be used to differentiate xanthine uroliths (urinary tract stones) from other types of uroliths. Also, high-pressure liquid chromatography of urine can be done to detect xanthine, hypoxanthine, and other purine metabolites.

 

 

Ultrasonography, double-contrast cystography, and intravenous urography are some additonal diagnostic tools that can aid in detecting uroliths and the location they are originating from. Uroliths generally do not show up on normal X-rays.

 

Xanthine uroliths in the urethra and bladder stones near the urethra may be detected by urethrocystoscopy, which uses a small flexible tube that is equipped with a camera and can be inserted into small spaces, in this case, the urethral passage. Small uroliths may be retrieved for analysis by removing fluid using a transurethral catheter, or using a method called voiding urohydropulsion. This latter method involves filling the bladder completely while the patient is anesthetized, and then emptying the bladder, after attempting to shake stones into the urethra, so that the stones can be collected.

 

 

Bacterial Infection of Bladder and/or Urethra in Dogs

 

The invasion and colonization of bacteria in the urinary bladder and/or the upper portion of the urethra may result in infection when the local defense system, which helps protect against infection, is impaired. Symptoms related to this type of infection include inflammation of the affected tissue and urinary difficulties.

 

Dogs of all ages can be affected, but vulnerability increases with advancing age. In such cases, stone formation, prostate disease, and tumors are frequently seen. Additionally, female dogs are more susceptible to bacterial infections of the lower urinary tract than males.

 

Symptoms and Types

 

Some dogs with bacterial infections of the lower urinary tract may not show any signs, but many more do. A few of the more common signs include:

 

• Difficulty urinating
• Blood in urine (hematuria)
• Cloudy or malodorous urine
• Frequent urination, but only in small amounts
• Urinary incontinence, especially during confinement or at places that are not customary (i.e., locations he has not peed before)
• Urination when bladder is touched (occasional)

 

Causes

 

E. coli, Staphylococcus, and Proteus spp. account for more than half of all cases of bacterial infections of the lower urinary tract. Less common bacteria include Streptococcus, Klebsiella, Enterobacter, Pseudomonas, and Corynebacterium spp.

 

Diagnosis

 

You will need to give a thorough history of your dog’s health, including the onset and nature of the symptoms, to your veterinarian. He or she will then perform a complete physical examination as well a biochemistry profile, urinalysis, and complete blood count (CBC). Although the results of the CBC and biochemistry profile are often normal, urinalysis findings will provide valuable information for initial diagnosis. For instance, pus, blood, or proteins are often seen in the urine. The urine sample, which is taken from the bladder with a syringe, is then cultured to grow the causative bacteria (allowing for sensitivity testing).

 

Once the bacteria is identified, your veterinarian will recommend suitable antibiotics for treatment. X-rays and ultrasonography of the lower urinary tract may also reveal the presence of stone or other abnormal lesion.

 

 

 

Azotemia and Uremia in Dogs

 

Azotemia is defined as an excess level of nitrogen-based substances compounds such as urea, creatinine, and other body waste compounds in the blood.

 

Azotemia is defined as an excess level of nitrogen-based substances compounds such as urea, creatinine, and other body waste compounds in the blood. It can be caused by higher than normal production of nitrogen-containing substances (with high protein diet or gastrointestinal bleeding), improper filtration in the kidneys (kidney disease), or reabsorption of urine back to bloodstream.

 

Uremia, meanwhile, also leads to an accumulation of waste products in the blood, but is due to improper excretion of the waste products through the urine because of abnormal kidney function.

 

Symptoms and Types

 

• Weakness
• Fatigue
• Vomiting
• Diarrhea
• Depression
• Dehydration
• Constipation
• Weight loss (cachexia)
• Loss of appetite (anorexia)
• Bad breath (halitosis)
• Muscle wasting
• Hypothermia
• Poor haircoat
• Unnatural lack of color in the skin
• A minute red or purple spot on the surface of the skin as the result of tiny hemorrhages of blood vessels in the skin (petechiae)
• The escape of blood from ruptured blood vessels into the surrounding tissue to form a purple or black-and-blue spot on the skin (ecchymoses)

 

Causes

 

• Low blood volume or blood pressure
• Infections
• Fever
• Trauma (e.g., burns)
• Corticosteroid toxicity
• High protein diet
• Gastrointestinal bleeding
• Acute or chronic kidney disease
• Urinary obstruction

 

Diagnosis

 

You will need to give a thorough history of your dog’s health, including the onset and nature of the symptoms, to your veterinarian. He or she will then perform a complete physical examination, as well as a biochemistry profile, urinalysis, and complete blood count (CBC). The CBC results may confirm nonregenerative anemia, which is common in dogs with chronic kidney disease and failure. Hemoconcentration may also occur in some dogs with azotemia, whereby the blood thickens due to a decrease of fluid content.

 

Along with identifying abnormally high concentrations of urea, creatinine, and other nitrogen-based compounds in the blood, a biochemistry test may reveal high levels of potassium in the blood (hyperkalemia). The urinalysis, meanwhile, may reveal changes in urine specific gravity (a urinalysis parameter commonly used in the evaluation of kidney function) and abnormally high concentrations of protein in the urine.

 

Abdominal X-rays and ultrasound are two other valuable tools often used by veterinarians to diagnose azotemia and uremia. They can help in determining the presence of urinary obstructions and the size and structure of the kidneys — smaller kidneys are commonly found in dogs with chronic kidney disease, while larger kidneys are associated with acute kidney failure or obstruction.

 

In some dogs, a kidney tissue sample will be collected to confirm the diagnosis of kidney disease and also to eliminate the possibility of other acute or chronic kidney diseases that may be present.

 

 

 

Hyposthenuria in Dogs

 

The normal concentration and regulation of urine normally depends on an elaborate interaction between antidiuretic hormone (ADH), the protein receptor for ADH on the renal tubule (the tube that plays a role in the filtering, reabsorption, and secretion of solutes in the bloodstream), and excessive tension of the tissue within the kidney. Hyposthenuria is a clinical condition in which the urine is chemically imbalanced. This may be due to trauma, abnormal hormone release, or excessive tension in the kidney.

 

Abnormalities may also occur due to interference with the synthesis, release, or actions of ADH, damage to the renal tubule, and altered tension (tonicity) of the tissue within the kidney (medullary interstitium). There is no breed of dog that appears to be more or less affected by this condition.

 

Symptoms

 

 Symptoms will depend on the underlying cause of the disorder. Some of the more common ones include:

 

 

Causes

 

Any disorder or drug that interferes with the release or action of ADH, damages the renal tubule, causes medullary washout, or causes a primary thirst disorder.

 

Diagnosis

 

Your veterinarian will perform a thorough physical exam on your dog, taking into account the background history of symptoms and possible incidents that might have led to this condition. A complete blood profile will be conducted, including a chemical blood profile, a complete blood count, and a urinalysis, with emphasis on determining the urine specific gravity.

 

The latter test reveals the functional capability of the kidney in its capacity to eliminate waste molecules without eliminating excess nutrients or water. These tests may confirm a urinary condition, with a low urine specific gravity of 1.000 to 1.006 g/ml, and excessive amounts of alkaline phosphates (ALP) in the blood serum, which would suggest hypoadrenocorticism or primary liver disease. High cholesterol is another common finding in dogs with hyperadrenocorticism.

 

In dogs suffering from pyometra (a disease of the uterus) or pyelonephritis (urinary tract infection), leukocytosis, a type of white blood cell, will be raised and will be present in the urine sample, along with abnormal amounts of protein in the urine, a condition called proteinuria. Proteinuria is common in patients with pyelonephritis, pyometra, and hyperadrenocorticism. If an underlying condition of pyelonephritis is present, the urinalysis will also show inflammatory sediment or bacteria in the urine (bacteriuria). 

 

 

Other laboratory tests your doctor may want to conduct are adrenocorticotrophic hormone (ACTH) level checks in order to determine the cause of the hyperadrenocorticism, if found. That is, your veterinarian will want to distinguish a pituitary dependent versus an adrenal tumor. Visual imaging, using X-ray, may also be included to determine if the kidneys or surrounding urinary tract organs are damaged in any way. An intravenous pyelogram is the most accurate diagnostic technique for a visual examination of the kidneys, ureter, and urinary bladder. This is a minimally invasive procedure which uses an injection of contrasting material into the bloodstream, where it then collects in the kidneys and urinary tract and illuminates them on the X-ray.

 

An ultrasonography can be used to assess adrenal size, kidney and liver size and architecture, and uterine size (abnormal findings in the size of one or more of these organs may confirm an infection or reaction to infection). In addition, a magnetic resonance imaging (MRI) or computed tomography (CT) scan can be used to assess a pituitary or hypothalamic (which links the nervous system to the endocrine system via the pituitary gland) mass, which can be an associated cause of central diabetes insipidus or hyperadrenocorticism.

 

Drug-Induced Nephrotoxicity in Dogs

 

Drug-induced nephrotoxicity refers to kidney damage induced by medication administered for the purpose of diagnosing or treating another medical disorder. It is more commonly recognized in dogs than cats. And although drug-induced nephrotoxicity may occur in dogs of any age, older dogs are more susceptible.

 

Symptoms and Types

 

Signs associated with nephrotoxicity may include:

 

 

Causes

 

Nephrotoxicosis can be induced by the administration of pharmacologic agents (or drugs), which interfere with the blood flow to the kidneys as well as cause tubular dysfunction in the kidneys. If left untreated, the damage to the renal tubule cells may lead to tubular necrosis and even kidney failure. Risk factors that may increase the odds of developing drug-induced nephrotoxicity include dehydration, advanced age, and fever.

 

Diagnosis

 

When drug-induced nephrotoxicity is suspected, a veterinarian will often biopsy a portion of kidney tissue. This will help him or her identify kidney failure and also the proper course of treatment. Another useful diagnostic procedure is a urine analysis.

 

 

 

Nephrolithiasis in Dogs

 

Nephrolithiasis is the medical term for the condition in which clusters of crystals or stones — known as nephroliths or, more commonly, “kidney stones” — develop in the kidneys or urinary tract. The kidney is composed of thousands of nephrons, each consisting of blood capillaries and a series of tubes through which filtered fluid flows as urine is produced. The tubes of the nephron drain into ducts through which urine flows; these ducts eventually enter the renal pelvis and a tube through which urine follows into the ureter. Kidney stones or kidney stone fragments can also pass through this system of tubes and into the ureter, causing serious complications. 

 

Both dogs and cats are susceptible to kidney stones. However, some breeds of dog are more susceptible to certain types of kidney stones than others. For example, kidney stones containing calcium and oxalic acid (known as calcium oxalate nephroliths) are more likely to be found in Lhasa Apsos, Yorkshire Terriers, and Miniature Poodles. Kidney stones containing uric acid (known as urate nephroliths), on the other hand, typically affect Dalmatians, Yorkshire Terriers, and English Bulldogs.

 

Symptoms and Types

 

Many dogs with kidney stones have no apparent signs; that is, the nephroliths are often not detected until diagnostic testing is done for other medical problems. Some symptoms that may occur include blood in urine (hematuria), vomiting, recurrent urinary tract infections, painful difficult urination (dysuria), and frequent urination with small volume of production (polyuria). Other symptoms may appear but vary depending on the location and type of the stones.

 

Note that some nephroliths may be “inactive”; meaning, they are not infected, not progressively enlarging, and not causing obstruction or clinical signs. Inactive kidney stones may not require removal, but should be monitored periodically (via urine analysis for example) for any changes.

 

Causes

 

There are a number of causes and risk factors that may contribute to the development of nephrolithiasis and the development of uroliths, such as the oversaturation of stone-forming material’s in the dog’s urine. Other potential causes include increased levels of calcium in the urine and blood, diets that produce high (alkaline) urine pH, and recurrent urinary tract infections.

 

Diagnosis

 

You will need to give your veterinarian a thorough history of the dog’s health, including the onset and nature of the symptoms. He or she will then perform a complete physical examination, ultrasound imaging, and urinalysis. However, in order to confirm the diagnosis, identify the mineral content of the stones, and develop a proper course of treatment, pieces of nephroliths must be retrieved for analysis. This is usually achieved by performing a procedure known as extracorporeal shock wave lithotripsy (ESWL), in which stones are broken up within the urinary tract using sound waves.