Have you ever had an older dog start peeing in the house and wondered if it could be related to kidney function? Today, we are going to discuss what the kidneys do, what happens in kidney disease, and common signs and symptoms owners may notice.

The kidneys function primarily as a filter, allowing waste and excess nutrients to be excreted through the urine while helping maintain the right amount of fluid in the blood.

The glomerulus, which functions like a microscopic colander, allows small compounds floating in the blood to cross into urine.

From the glomerulus, waste flows through a set of tubules before draining into the bladder. These tubules are where fluid and electrolytes are reabsorbed to maintain an appropriate amount of fluid in the blood and pH in the body.

Having the appropriate amount of fluid helps ensure proper blood flow and blood pressure are maintained to support normal body function. The body also has sensors in the kidney that detect changes in blood pressure and stimulate adjustment.

These are factors that put more stress on the kidneys, such as:

Pre-renal changes are common and often resolve when the underlying cause resolves or is managed. If left untreated long term, they can lead to permanent kidney damage, but may be reversible if caught in a timely manner.

This is when the kidney itself is not functioning properly. Renal damage can be classified as:

There are two primary ways kidneys stop functioning properly:

This is when urine is unable to leave the body and backs up.

Post-renal changes are most commonly caused by a blockage, such as kidney stones, but can be caused by other conditions. Urinary blockages can become an acute emergency and lead to serious health complications quickly.

When incomplete or one-sided, post-renal causes can be more chronic. When treated promptly, the kidney may be able to recover some or all function, though permanent damage is possible.

Regardless of cause, we manage stress on the kidneys in a few key ways. If there is a blockage, removing it is the priority. Beyond that, treatment options are relatively consistent:

Because the kidneys main function is filtration, fluid support is often important. This may help:

Diet is often adjusted to reduce strain on the kidneys. Renal diets have reduced protein and certain electrolytes that can increase strain or are poorly eliminated and may worsen symptoms.

When diet alone is not sufficient, some electrolytes can be bound with additional medication.

Blood pressure medication may be used to reduce pressure in the glomerulus and helps prevent excess metabolites from being pushed into the urine.

Handling and preventing urinary tract infections is also important when dealing with kidney disease, with urinary tract infections being among the most common complications. These are commonly well managed with appropriate antibiotics.

Fortunately, the kidneys have significant reserve capacity, meaning small steady changes can sometimes be tolerated without changes in kidney function on bloodwork. Chronic or significant changes can result in abnormal kidney bloodwork values.

Once there is damage to the kidneys, they are unlikely to resolve completely. Kidney disease is more often managed than cured, with treatment focused on slowing progression and improving your dog’s experience.

Early disease, as well as pre-renal and minor post-renal causes of kidney strain, may cause little to no symptoms. The most common early signs may include changes in urination habits, such as:

As disease progresses, signs may include:

A complete lack of ability to expel urine can quickly become an emergency.

Like with any disease, early detection improves outcomes. This is one of the many reasons your veterinarian may recommend screening bloodwork. Finding and addressing abnormalities before your dog feels sick can help delay symptoms.

Once symptoms start, treatment may help reduce symptoms by reducing stress on the kidneys, but damage to the kidneys cannot be undone. In chronic kidney disease, steady progression is generally expected.

When kidney disease is combined with damage to other organs, management can become complicated, sometimes involving conflicting needs.

If your dog has recently been diagnosed with kidney disease, the changes can feel overwhelming, especially when you are trying to manage frequent bathroom breaks day and night in the middle of everyday life.

If you are struggling with lapses in potty training, training your dog to use indoor relief areas can sometimes be easier than trying to be available ever time your dog needs to go out.

Picky eating, especially with kidney diets, can be a challenge. How strict you need to be about diet depends on severity and certain electrolyte levels. While “cheating” the diet can be very tempting, it can often lead to increased abnormalities that can make dogs feel worse, which may further worsen appetite.

This can exacerbate quality-of-life concerns. If your dog is struggling to reliably eat the diet your veterinarian has prescribed, reach out to your veterinarian to see whether appetite or nausea support may be possible.