If the dog's kidneys are swollen, this is usually due to kidney inflammation or poisoning. In rare cases, it can also be caused by kidney stones, a urinary tract obstruction or even life-threatening kidney cancer.
What is striking here is that even in acute kidney failure, the symptoms only appear when they have already lost ⅔ of their function. The functions of the kidneys include:
- Regulation of fluid and electrolyte balance
- Detoxification of the body
- Regulation of acid-base balance
- Production of certain hormones
- Regulation of blood pressure [1]
If the kidneys are swollen, they often lose some of these functions. Below you will learn about the 5 most common causes.
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#1 Kidney inflammation
If the kidneys become inflamed, doctors also speak of an upper urinary tract infection. The most common triggers include:
- bacteria
- Kidney stones
- Parasites
- Other illnesses [2]
In most cases, however, bacteria are behind it. Since the body is busy fighting inflammation, the function of the kidneys also decreases.
Such inflammations can usually be recognized by the fact that the dog's urine smells, takes on a different color and the four-legged friend has a fever. Other typical symptoms are:
- Blood in urine
- Swollen kidneys
- Strong thirst
- Problems peeing
- Lack of motivation
- weight loss
- Frequent urge to urinate
- Nausea and vomiting
- stomach pain [3]
For diagnosis, the vet primarily examines the blood and urine. Depending on the suspected cause, additional tests may also be used.
Since such inflammations are usually caused by bacteria, antibiotics are mainly used to treat them. The vet can give you recommendations for this.
When dogs' kidneys become inflamed, they often swell. Typically, such infections also cause problems with urination, a strong smell of urine and a strong thirst. Many four-legged friends also get a fever.
#2 Urinary tract obstruction
When the flow of urine between the kidneys and the urethra is obstructed, doctors speak of a “urinary tract obstruction”. Typical causes of this are:
- Prostate diseases
- Severe inflammation
- Bladder and kidney stones
- Tumor disease
- Scarring from injuries
- Ulcers [4]
Depending on the causes and severity, the symptoms can vary greatly. However, it is usually caused by bladder and kidney stones, which cause the kidneys to become increasingly swollen.
What is typical here is that dogs want to pee, but then either nothing or very little urine comes out. Other classic signs include:
- Blood in urine
- Pain when peeing
- Loss of appetite
- Dog starts whining
- Depressive behavior
- Dog always has to go out
- Dark urine color [5]
For diagnosis, the abdominal cavity is usually palpated, an ultrasound examination is carried out, if possible some urine is taken and a blood sample is examined in the laboratory.
If it is actually due to bladder and kidney stones, the vet will usually try to flush them out. If that doesn't work, surgery may be necessary. [6]
If there is a urinary tract obstruction, the dog's urine cannot be excreted from the kidneys through the urethra. As a result, urine accumulates inside and swelling of the kidneys occurs. Problems with urination are the most common symptom here.
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#3 Poisoning
Don't let the media tell you anything. Poison baits are only very rarely the cause of poisoning. As a rule, it is due to the ignorance of the owners.
For example, many first-time owners are not aware that even ordinary foods can have a toxic effect on dogs. This includes:
- Cocoa products such as chocolate
- Individual types of nuts such as macadamia nuts
- Allium vegetables such as onions and garlic
- Grape products such as raisins and wine [7]
But toxic plants, cleaning agents and other chemicals can also be triggers. The symptoms of this can only appear days later.
Since the dog's kidneys are responsible for breaking down toxins, they suffer the most and often swell. The most common symptoms here include:
- Dog vomits
- Sudden cramps
- Loss of appetite
- Dog drools a lot
- Constant diarrhea
- Foam at the mouth
- Dog is shaking [8]
Depending on the amount of poison swallowed, it could be a veterinary emergency. If you suspect something, you should take action immediately.
When dogs get poisoned, the kidneys take the brunt of it. This explains why toxins can also cause the kidneys to swell or even fail. Typically, affected four-legged friends vomit very often.
#4 Kidney stones
Kidney stones are small crystals that form in the kidney from substances in urine. Very small kidney stones are usually harmless and not a cause for concern.
However, once they reach a certain size they can cause problems. Female dogs are said to be affected more often. The following breeds also have an increased risk:
- Miniature Schnauzer
- Lhasa Apso
- Yorkshire Terriers
- Bichon Frize
- Shih Tzu [9]
Kidney stones can also cause a swollen kidney in two different ways. On the one hand, it can irritate the kidneys and thereby cause an infection.
On the other hand, the stones can also get into the urinary tract and block it. Then there is talk of a “urinary tract obstruction”. Typical symptoms of this are:
- Blood in urine
- stomach pain
- Frequent urination
- Constant licking of genitals
- weight loss
- Constant urinary tract infections
- Dog refuses food
- Frequent vomiting [10]
Depending on the type and size, different therapeutic approaches are possible. The options start with medication and end with surgery.
When kidney stones form in dogs, they can cause the kidneys to swell when they reach a certain size. It can typically be recognized by the fact that dogs have to urinate frequently, constantly lick their genitals or even have blood in their urine.
#5 Kidney cancer
Kidney cancer can either form directly in the kidney or have spread from another part of the body. Older dogs are more commonly affected.
Unfortunately, the exact cause of almost no type of cancer is known. Although kidney cancer is considered relatively rare in dogs, the following breeds are at increased risk:
- German shepherd dog
- Labrador retrievers
- Malamutes
- Springer Spaniel
- Toy Poodle
- Golden retrievers
- cocker spaniel [11]
One of the first symptoms here is that dogs become unusually thirsty and have a constant urge to urinate. Other typical signs of this are:
- Loss of appetite
- Unusual behavior
- Swollen kidneys
- Dog loses weight
- Listless behavior
- Nausea and vomiting
- Feeling of weakness [12]
The treatment depends on the size and stage of the tumor. In most cases, an attempt is made to remove the tumor surgically.
If the cancer has already spread, chemotherapy is usually carried out. The earlier the tumor is diagnosed, the better the chances of survival.
If a tumor forms in the dog's kidneys, visible symptoms will occur as it progresses. Among other things, affected four-legged friends have problems urinating, have swollen kidneys and constantly have to vomit.
Rare causes
- Kidney clots
- Kidney abscess
- Old age
- Hydronephrosis
- Renal lymphoma
- Cyst in the urinary tract [13]
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