There are multiple reasons why a rabbit can stop urinating. There may be a problem at the prerenal level (before the kidneys), renal (in the kidneys themselves) or postrenal (after the kidneys, that is, in the urinary tract). In either case, it is important to act urgently, since in most cases the process is potentially reversible if you act quickly and effectively. Only in this way will we prevent irreversible kidney failure from occurring.
If you are wondering why your rabbit is not urinating and you want to know what the possible causes and treatment are, keep reading this article of our site.
What is the rabbit's urinary system like?
The urinary system of rabbits is very similar to that of carnivores. It is made up of two kidneys, two ureters, a urinary bladder, and a urethra.
The kidneys are voluminous, dark in color and smooth in surface. The right kidney is located more cranial (in front) than the left, and both are located very laterally in the retroperitoneal space of the abdomen. In some individuals, the kidneys are surrounded by a large amount of fat that displaces them ventrally. It should be noted that the kidneys of rabbits play a fundamental role in calcium metabolism, since they are capable of excreting or conserving calcium according to the metabolic needs of each moment.
From the kidneys come the ureters, two fine tubes that carry urine from the kidneys to the urinary bladder.
The urine bladder is located in the caudal area of the abdomen, supported by the median vesical ligament. It is large, with thin and extensible walls. The urethra comes out of the bladder, which is responsible for transporting urine from the bladder to the outside during urination.
As regards the urine produced by rabbits, two important aspects must be highlighted:
- Urine has a cloudy appearance, because its alkaline pH causes calcium to precipitate, giving rise to calcium carbonate.
- Sometimes urine may appear red due to the presence of plant pigments naturally present in foods, which should not be confused with hematuria (presence of blood in the urine). To differentiate it, it will be enough to make a urine strip to detect the presence of blood.
Why isn't my rabbit urinating?
First, we will define the terms oliguria and anuria. Oliguria consists of decreased diuresis (excretion of urine) and anuria consists of total cessation of diuresis. Therefore, when a rabbit urinates little or not at all, we will say that it presents oliguria or anuria, respectively.
Both oliguria and anuria are clinical manifestations that accompany some alterations or pathologies of the urinary system. These alterations can be:
- Prerenal (before the kidneys): Any factor that decreases the flow of blood to the kidney will decrease the amount of blood filtered by it and, consequently, the amount of urine produced. In this case we speak of prerenal azotemia, which is an increase in urea and creatinine due to a cause that is found before the kidneys.
- Renal (in the kidney itself): the causes of acute kidney injury (AKI) usually present with oliguria (although in sometimes the volume of urine may be increased).
- Postrenal (after the kidneys, in the urinary tract): any cause that prevents the elimination of urine to the outside, such as obstruction, urinary tract rupture or neurological causes, will produce oliguria/anuria. In this case we speak of post-renal azotemia, that is, an increase in urea and creatinine due to a cause that is found after the kidneys.
Next, we describe the different causes of oliguria or anuria in rabbits, that is, they cause a rabbit to be unable to urinate. We will first explain the post-renal causes (the most common), we will continue with the renal causes (aquatic kidney injury) and we will finish with the pre-renal ones.
Hypercalciuria
As we have already mentioned, the presence of calcium carbonate crystals in the urine of rabbits is normal, since the alkaline pH favors the precipitation of calcium. However, when the supply of calcium from the diet is excessive, it will be eliminated via the kidneys and there will be a calcium carbonate deposit in the bladder of the urine, causing a strong dilatation of the organ.
The Clinical signs, in addition to oliguria or anuria, may include:
- Hematuria: presence of blood in the urine.
- Dysuria: difficulty urinating. Urination is often painful and manifests as a stooped posture.
- Muddy urine: if you manage to urinate, the urine will be much thicker and whitish than normal. In this other article we talk more in depth about white urine in rabbits.
- General signs such as depression, anorexia (loss of appetite) and weight loss.
- Perineal dermatitis: calcium carbonate deposits in the urine have an irritating action on the skin of the perineum, causing perineal dermatitis.
Urolithiasis
Urolithiasis is defined as the presence of calculi or uroliths in the urinary tract It is a process closely linked to hypercalciuria, since, in most cases, uroliths are formed by calcium carbonate. Hypercalciuria, together with other factors such as reduced water intake, diets rich in calcium oxalate, or changes in urinary pH due to urinary tract infections, favor the formation of stones. These uroliths can accumulate in the urinary bladder without causing any symptoms, but when they reach a sufficient size to obstruct some point of the urinary tract, they cause symptoms. The clinical signs are very similar to those seen in hypercalciuria.
Other causes of urinary tract obstruction
In addition to urolithiasis, there are other processes that can cause obstruction of the urinary tract and, consequently, cause a rabbit not to urinate, that is, it can present oliguria or anuria. These processes include:
- Adhesions: these are complications that can appear after surgery of the abdominal cavity, especially when excessive trauma is generated or a inadequate suture material.
- Abscesses: Abscesses located in organs of the abdominal cavity (for example, in the mesenteric nodes) can externally compress the urinary tract in some point and cause oliguria/anuria.
- Tumors: like abscesses, any tumor that affects the organs of the abdominal cavity can externally compress the airways urinary. Similarly, the presence of a tumor in the urinary tract itself (such as a leiomyoma in the wall of the urinary bladder) can reduce the lumen of the ducts and cause an obstruction.
- Clots: The presence of a clot inside the urinary tract can occlude the lumen of the duct and cause an obstruction.
When urinary obstruction is maintained over time, the urinary tract may break, with the consequent outflow of urine into the abdominal cavity (uroabdomen).
Bladder paralysis
It is a pathology of neurological origin. The bladder loses its ability to contractile, which prevents urination. As a consequence, there is excessive dilation of the urinary bladder.
Acute Kidney Injury (AKI)
Pathologies in which acute damage to the nephrons occurs will lead to acute kidney injury. The nephrons are the functional unit of the kidney, so each kidney has about a million nephrons. The main causes of AKI in the rabbit include:
- Nephrotoxicosis: due to drugs, toxic (such as ethylene glycol from antifreeze in cars) or endogenous pigments (hemoglobin or myoglobin).
- Nephritis: is a general inflammation of the kidney that can be seen in systemic infectious diseases (encephalitozoonosis, leptospirosis, etc.) or in inflammatory processes (metritis, sepsis, etc.).
- Ischemic necrosis due to hemorrhagic viral disease.
Prerenal azotemia
As we have already mentioned, any cause that decreases blood flow to the kidney will decrease the volume of filtered blood and, therefore, the volume of urine. The specific causes will be:
- Cardiac pathologies that decrease cardiac output.
- Shock, due to hypovolemia or hypotension.
- Dehydration.
- Renal arterial thrombosis: in rabbits it is associated with hemorrhagic viral disease.
What do I do if my rabbit can't urinate?
First of all, you should know that if your rabbit cannot urinate, it is important that you see your vet as soon as possible. In the event of oliguria or anuria, it is urgent to make a rapid diagnosis, since in most cases the situation is potentially reversible. However, if we do not act quickly and institute early and effective treatment, kidney damage can lead to irreversible kidney failure
The treatment of each of the causes of anuria will be as follows:
Treatment of post-renal causes
This includes hypercalciuria, urolithiasis, other causes of obstruction or bladder paralysis. If the urinary bladder is very distended, it is important to empty it by catheterization or bladder puncture to avoid two complications. On the one hand, the rupture of the urinary tract and the consequent uroabdomen. On the other hand, the retrograde accumulation of urine in the urinary system, which will reach the kidney and cause hydronephrosis (dilation of the renal pelvis and calyces due to accumulation of urine that causes kidney degeneration). Once the bladder has been emptied of urine, treatment will be instituted depending on the specific cause.
In the case of hypercalciuria/urolithiasis, correct the management factors that have influenced the appearance of the process (reduce the intake of calcium, stimulate exercise and water intake). In addition, analgesics will be administered to relieve pain, diazepam to prevent urethral spasm, bicarbonate to alkalinize the urine and, if necessary, antibiotics to treat secondary infections. When the stones cannot be eliminated via the urine with pharmacological treatment, surgical treatment will be necessary to remove them.
Treatment of renal causes
After rehydrating the animal with the appropriate fluid therapy, diuretics will be administered in order to restore normal diuresis. In addition, the primary cause must be treated specifically.
Treatment of prerenal causes
After an accurate diagnosis, appropriate treatment will be instituted to increase renal blood flow and achieve reversal of azotemia (fluid therapy to rehydrate, increase blood pressure, etc.).
