Acute Kidney Injury in Dogs
Acute kidney injury is sudden, severe damage to the kidneys. It can be caused by ingestion of toxic substances, poor blood flow to the kidneys or infections, such as leptospirosis (infection with bacteria called leptospires). People can also get leptospirosis, so if your dog is infected, it's important to speak with a physician.
Toxic substances that can cause acute kidney injury if ingested by dogs include antifreeze, poisonous plants, some over-the-counter or prescription medications, and certain foods, such as grapes or raisins. (Harmful substances can also build up inside the body because of other diseases.) Dogs that ingest any of these substances should be seen by a veterinarian right away.
Mild kidney damage in dogs might go unnoticed, but severe cases can cause loss of appetite, weakness, dehydration, mouth sores, vomiting, diarrhea, and low urine output. It is important to consult a veterinarian to determine whether the problem is acute or chronic (ongoing) and to find the cause. Tell your vet about foods your dog has eaten, medicines it takes, and any behaviors of note. Your vet will likely test your dog's blood and urine.
With treatment, some portion of the injured kidney might recover. Treatment involves targeting the underlying cause of the damage and can include IV (intravenous) fluids, feeding support, insertion of a catheter (a tube to help drain urine from the body), and medicines to increase urine output.
If a dog doesn't produce urine despite other treatment, dialysis might be considered when available. Dialysis is a treatment that removes waste products and excess fluid from the blood when the kidneys can't remove them adequately. In dogs with severe acute kidney injury, dialysis can help control dangerous changes in the blood while the kidneys have time to recover.
In severe cases in which treatment can't restore kidney function and the dog’s condition can't be managed, euthanasia (humanely ending a pet's life) may be considered.
Urinary Stones in Dogs
Urinary stones (also called uroliths or calculi) form when minerals in urine collect into crystals and then form larger masses. Dogs can develop stones in the kidneys, ureters, bladder, or urethra. Urinary stones have different names, depending on their mineral content, but the common types are struvite, calcium oxalate, and urate. Stone formation depends on factors such as urine chemistry, infection, diet, urine volume, medications, and genetics.
Small stones might cause no symptoms. Larger stones can irritate a dog's bladder or block urine flow, causing pain, bloody urine, and difficulty urinating. Stones in the ureter can cause vomiting, tiredness, and pain near the kidneys. If a ureter stays blocked, the kidney can be destroyed.
A veterinarian can sometimes feel stones during a physical exam. X-rays, urine tests, ultrasound, and other tests can help locate them. Treatment of urinary stones depends on the type and location and can include surgery (to remove the stones), sound-wave treatment (to break up the stones), a special diet, and medication. Removed stones are often tested to determine their type.
Urinary stones can be an emergency when they cause a urethral obstruction.
Urinary Tract Blockage in Dogs
If a dog's urinary tract becomes blocked anywhere below the kidneys (see diagrams in The Urinary System of Dogs), urine and waste products can back up, damaging the kidneys.
A urethral blockage occurs when urine can't pass normally through the urethra, the tube that carries urine out of the body.
A blocked ureter means urine can't flow normally from a kidney to the bladder. If the blockage is complete or lasts too long, urine can build up in the affected kidney and damage it.
Common causes of blockage include stones, tumors, and blood clots. Most commonly, a urinary stone lodges in the urethra and blocks urine flow, especially in male dogs. Early on, the dog might strain and pass only drops of urine or a weak stream. Complete blockage causes toxins to build up and can lead to collapse or death. Complete obstruction is, therefore, an emergency.
If urine flow is blocked, the kidneys and ureters can become abnormally enlarged. Complete blockage of both kidneys or the urethra is very dangerous. Partial blockage or blockage on one side might be less obvious but can still cause lasting damage.
Signs and Diagnosis of Urinary Tract Blockage in Dogs
Dogs with a blockage in the urethra might strain to urinate, pass only small amounts, cry out, or have blood in their urine. The abdomen might be painful, and toxic waste quickly builds up in the blood. Vomiting, dehydration, low body temperature, weakness, and abnormal heart rhythm are other possible signs that a dog has a urethral blockage. Veterinarians diagnose a blockage on the basis of a dog's symptoms, a physical exam, blood test results, and often ultrasound or other imaging results.
In dogs with a blockage of a ureter, signs of illness can be more vague and can include pain, vomiting, and decreased appetite. A vet might diagnose a ureteral blockage using a physical exam, blood and urine tests, and imaging such as ultrasound or x-rays.
Treatment of Urinary Tract Blockage in Dogs
Treatment aims to restore urine flow by relieving the blockage—for example, by pushing a stone back into the bladder with a catheter tube or removing it surgically. If pushed back into the bladder, the stone is usually removed later so it doesn't block again.
Surgery is often needed for blockages, though some stones or other blockages pass out of the dog's body on their own. Sometimes, part of the ureter or urethra must be removed, or a badly damaged kidney must be taken out.
A subcutaneous ureteral bypass (SUB) is a device that creates a new pathway for urine to flow from the kidney to the bladder when a ureter is blocked or severely narrowed. The device uses small tubes placed in the kidney and bladder, connected by tubing that runs under the dog's skin. A veterinarian can access the device through a small port under the skin to flush it and help keep it working properly. A SUB might be recommended when the ureter can't be unblocked or repaired successfully.
IV fluids help support kidney function and also correct dehydration and chemical imbalances in the blood caused by the urinary tract blockage.
A dog showing signs of complete urinary blockage needs emergency care right away. Signs can include repeated straining to urinate without producing urine, frequent attempts to urinate with only a few drops or no urine, and crying or other signs of pain while trying to urinate. Other signs can include vomiting, weakness, loss of appetite, or a painful or swollen abdomen. A complete blockage can quickly cause dangerous changes in the blood and can lead to death if it is not treated promptly.
For More Information
Also see professional content regarding acute kidney injury in dogs and urinary stones (urolithiasis) in dogs.
