What is kidney disease in cats?
Kidney disease in cats occurs when the animal’s kidneys are not functioning properly. This can lead to kidney failure when both kidneys are affected and the cat can no longer adequately remove waste products from their system.
The kidneys are responsible for several important processes within the body. They filter out and eliminate waste products from the bloodstream, maintain normal water and salt (electrolyte) balance, and produce hormones which control blood pressure and red blood cell production.
If the kidneys are not functioning normally for more than three months, it is referred to as ‘Chronic’ Kidney disease (CKD). CKD is one of the most common conditions to affect older cats (those over 7 years of age). It occurs when there is long term, irreversible damage to the kidneys. It is a progressive condition, but the rate at which this occurs can be highly variable between cats. Some cats can live for many years with a gradual worsening of signs. The sooner a diagnosis is made and treatment started, the better the outcome for the animal.
Kidney diseases which are shorter in duration are referred to as ‘Acute’ Kidney Injury or Failure. Depending on the cause and severity and unlike CKD, some animals may make a full recovery from acute kidney disease.
What are the causes of kidney disease in cats?
In most cases, the exact cause of CKD is unknown and research is ongoing. Chronic kidney disease in cats is sometimes known to be caused by:
- Ongoing inflammation of the glomeruli (individual units within the kidney)
- Damage to the kidneys following a kidney infection
- Toxin damage
- Excess protein loss through the kidneys
- Abnormal formation of the kidneys at birth
- Kidney tumours e.g; Lymphoma
- Inherited diseases such as Polycystic kidney disease in certain breeds, e.g; Persians.
Acute kidney failure in cats can be caused by:
- Heart failure
- Blockage of part of the urinary system e.g; bladder or kidney stones
- Certain medications
- A sudden drop in blood pressure e.g., due to blood loss, general anaesthesia
- Certain types of tumour
What are the signs of kidney disease in cats?
In the early stages of CKD, there may be very few signs. The symptoms progress as kidney function declines and the cat starts to suffer more consequences of this. The commonly seen symptoms are:
- Increased thirst
- Increased urine production
- Reduced appetite
- Gradual weight loss due to poor appetite and loss of protein in the urine
- Vomiting due to toxin buildup in the system
- Lethargy/sleeping more
- Weakness due to muscle wastage, anaemia and low blood potassium
- Dehydration due to excess water loss into the urine
- Bad breath (halitosis) — Due to toxin build-up and oral and gastric ulceration
In the latter stages of kidney disease in cats, the animal will start to feel very unwell, feeling constantly sick, dehydrated and weak. They will also be in significant pain from ulceration of the mouth and stomach lining and toxin build-up leading to headaches, blindness and eventually collapse.
In acute kidney failure, the cat will show signs in a matter of hours or days. They can include:
- Sudden anorexia (not eating)
- Vomiting (sometimes with blood)
- Strange smelling breath
- Some cats may urinate more than usual, while others may produce no urine at all.
Cats with acute renal failure will feel very unwell in a short space of time. They often seem to be in significant pain due to swelling of the kidneys and may collapse or cry constantly.
How is kidney disease diagnosed in cats?
None of the signs are specific for chronic kidney disease in cats, so we will need to carry out a number of tests to find out what is causing them.
Initially, your cat will need a thorough clinical examination in a free consultation with one of our vets. In addition to the presence of the signs above, we may be able to feel that your cat’s kidneys are enlarged, painful or shrunken.
There will often be an increase in kidney values on blood tests. These include Urea, Creatinine, Phosphate and electrolyte imbalances. In addition, a newer, more sensitive marker ‘SDMA’ is helping us to detect the condition at an earlier stage. Even so, we are unable to detect kidney failure until 66% or more of the kidneys are not working normally.
Before your appointment with the vet, we will ask for you to collect, or hospitalise your cat to obtain, a urine sample. Cats with kidney failure will usually have protein in their urine and sometimes blood or cells dependent on the cause.
If your cat is compliant, we will advise blood pressure testing. Blood pressure is often high due to excessive salt retention by the kidneys. We may also suggest X-rays or an ultrasound scan to check for conditions such as polycystic kidneys, kidney stones or tumours.
By combining the results of the above tests, we can ascertain whether your pet is more likely to be suffering from acute or chronic kidney disease. This will affect the prognosis and long term management of your pet.
IRIS staging system
In cases of CKD, we use the IRIS staging system to ‘stage’ your cat’s kidney disease. IRIS Stage I is the mildest form of the disease, through to IRIS Stage IV which is the most advanced form. By staging your cat, we can provide the most appropriate medication to support your cat’s kidneys and offer the most accurate prognosis.
Treatment for kidney disease in cats
Acute renal failure in cats (ARF) is potentially reversible if diagnosed early and treated aggressively. A cat with ARF will require admission into the veterinary hospital for intravenous fluid support to correct rehydration, flush out toxins and balance electrolytes.
We can provide your cat with anti-sickness medications, gut protectants and, where appropriate, intravenous antibiotics to aid their recovery.
Prognosis of kidney disease in cats
The prognosis is always guarded as the kidneys have very limited capacity to regenerate. Short term survival and long term outlook is dependent on the cause, how soon treatment is given following the insult to the kidneys and whether there was already an underlying kidney condition or another disease that made your cat more susceptible.
For example, a cat with acute kidney disease due to urinary tract obstruction or infection could make a full recovery from the kidney disease when appropriate treatment is given to relieve obstruction or infection. Sadly, in contrast, most cats with antifreeze toxicity do not survive as severe, irreparable damage has been done to the kidneys by the time they show symptoms.
Therefore, the aim of treatment for chronic kidney disease (CKD) is to improve the cat’s quality of life by controlling the symptoms and to slow down the progression of the disease.
Dietary treatment for Kidney Disease
In the early stages, CKD can often be successfully managed with a specialised kidney diet. These diets are balanced to help support the reduced kidney function. They have restricted nutrient levels of protein, as protein breakdown products have to be excreted via the kidneys and can cause further damage. They are often also lower in phosphate, which the kidneys can no longer excrete efficiently, and higher in potassium, which the kidneys can no longer retain.
Medication for Kidney Disease
Phosphate binders e.g; Pronefra, Ipakitine can be used to reduce excessive phosphate and toxin levels in your cat’s blood.
ACE inhibitors e.g; Benazecare, Fortekor may be used if your cat’s blood pressure is raised to prevent further damage to the kidneys and any other secondary effects of high blood pressure e.g; stroke, heart disease and blindness.
Angiotensin blockers such as Semintra can be used to reduce blood pressure and protein loss through the kidneys. Excessive protein loss through the kidneys is associated with a shorter life expectancy in a cat suffering from CKD.
Potassium supplements may be required in addition to diet, and appetite stimulants and antacids may be prescribed for cats with poor appetite or gastric ulcers.
How to prevent kidney disease in cats
- Make it easy for your cat to pass urine. Your cat’s litter tray should be located somewhere they feel comfortable and safe. Clean the litter tray regularly so they are not put off using it.
- Take your cat for regular health checks. Routine check-ups at the vets will make it more likely that any signs of disease will be picked up early before they develop into serious conditions.
- Encourage your cat to drink plenty of water. Ideally use a water fountain as cats enjoy running water, or a large bowl of freshwater to encourage your cat to drink more.
- Use wet food. Tins or pouches of wet food will increase your cat’s water intake compared with a dry diet alone.
- Don’t let your cat become overweight. Obesity can lead to multiple health problems, including diabetes, which can lead to kidney failure.
If you are concerned that your cat is experiencing signs of kidney disease, don’t hesitate in booking a free consultation with one of our vets. If you aren’t already registered with us, it’s quick and easy to do online.