Kidney disease is one of the leading killers of cats.
Although the average lifespan of cats is increasing, cases of progressive chronic kidney disease are also increasing. It’s important to pay attention to your cat’s usual appetite and activities so you do not miss the subtle signs of kidney disease. Check the following information about kidney disease and how to help your cat live a long life.
Cats age much faster than humans - an 11-year-old cat is like a 60-year-old human. It's said that cats trade their higher heart rate for a shorter lifespan, as the heart rate of cats is higher than that of humans. Thus, it's important to know your cat’s age so that you can take care of their health. The following chart is an approximation of your cat's age in human years.
It's important to observe your cat's appearance, appetite, water intake, quality and frequency of urination and bowel movements regularly in order to catch diseases early or prevent them. When you first start raising your cat, please take it to a veterinarian so they can check your cat’s age, the environment it has been raised in and its overall health.
Even if you see a veterinarian, your cat may have been so nervous that it couldn't receive a thorough examination. If you notice any changes in your cat's condition, try checking for the following signs yourself.
|Body Part||What to Check for||Possible Disease(s)|
|Light reflecting off of its eyes (its eyes are “sparkling”)||Hyperthyroidism|
|Its eyes have sunken in||Dehydration|
|The condition of the skin around the ears, nose and mouth has deteriorated||Skin disease or a tumor|
|Bad breath||Periodontitis, kidney disease etc.|
|Color of the Mucous Membrane||The whites of the eyes, the color of the gums||Anemia or jaundice|
|Fur||Stiff Fur||Poor nutrition or lack of self-grooming|
|Back||Cannot perceive being touched on the back||Obese or overweight|
|Abdomen||Muscle stiffness||Abdominal cavity tumor, mammary tumor|
|Paws||Long claws, pain when touched||Arthritis|
|Functions of the Kidney||・Evacuation of waste
・Regulation of water and minerals in the body
・Blood pressure regulation
|What Will Happen if Kidney Disease Develops||
・Failure to evacuate waste, which will lead to uremia
・The concentration of phosphorus will increase and the kidney will be damaged
・The hormones that regulate blood pressure will increase and high blood pressure will develop.
|Structure of the Kidney||
As seen in figure1, there are around 200,000 nephron structures that make up the glomerulus and renal tubules of one kidney.
Blood brought from the body to the kidneys are filtered through the glomerulus, and then water and necessary nutrients are reabsorbed by the renal tubules.
|What is Kidney Disease?||Kidney disease is when the kidney cannot perform its essential functions. Feelings of listlessness and nauseousness and symptoms of uremia and high blood pressure occur. In cats, when damage occurs in the renal tubules, water cannot be reabsorbed so the concentration of the urine changes. The color is lighter and the amount increases as well. Water intake increases because excessive urination happens, so even though your cat is drinking a lot of water, dehydration occurs. Usually, around 20-30% of the nephrons are functioning at a time. Only when 70% of the nephrons are not functioning is when symptoms appear. This is why it is difficult to detect kidney disease.|
|Relationship between Kidney Disease and Aging||Kidney disease is common in older cats, especially after age 7. A 7-year-old-cat is equivalent to a human in their mid-40s. After your cat turns 7, please schedule regular urine and blood tests.|
|Symptoms of Kidney Disease||Increased urination / Increased water intake / Vomiting / Anemia / Dehydration / High blood pressure|
It is said that cat’s kidneys are easily burdened, so they should drink more water to ease that burden. Cats that are given dry food (which has comparably low water content) will drink more water than those given wet food. However, the overall water intake of cats who are given wet food is higher because the water content of the food supplements the drinking water. For healthy kidneys, it is recommended that you give your cat wet food.
It's also important to give cats food that is low in phosphorus and sodium. It is difficult to excrete phosphorus from the kidneys if kidney functions deteriorate. Phosphorus will damage the kidneys, thus worsening kidney disease. Furthermore, if kidney functions deteriorate it's difficult to regulate water and sodium, so blood pressure rises easily which in turn causes the burden on the kidneys to rise.
If kidney functions deteriorate, it will be hard for your cat to expel toxins and other waste. If there is a problem, the values explained below will be high.
|Blood Urea Nitrogen (BUN)||The byproduct of protein after they are used as energy, nitrogen is a toxin that is difficult to excrete if kidney function has deteriorated. A high number on a BUN test means that your cat may be suffering from nausea or poor appetite.|
|Creatinine (Cre)||The standard value of Creatinine, a byproduct that is produced when muscles move, depends on the muscles in your cat's body. Creatinine can be used as an index of kidney health.|
|Phosphorus (P)||Although it is indispensable for the body, phosphorus levels rise when kidney functions deteriorate.|
Check cat’s urine for the presence of materials that are not usually found in urine. Urine tests can be faster than blood tests at detecting irregularities, so please have your cat take a urine test during its physical.
|Relative Weight||This number represents the density of urine. If the number is low, it means that the enrichment capability of the kidney has fallen. It's best to measure the morning urine, which has the highest relative weight.|
|Urine Protein||As kidney functions fail, protein also escapes through urine (although a small amount of protein is normally detected).|
|Urine Protein to Creatinine Ratio (UPC)||Measuring the ratio of creatinine to urine protein is a way to test kidney functions.|
This test is used to confirm that the size and makeup of the kidneys are not irregular.
The most accurate urine test is done via paracentesis vesicae (taking a sample directly from the bladder) done at the animal hospital. However, we have some tips on collecting a urine sample at your home.
Quickly put a tray under your cat's bottom when it is about to urinate. Do not force it if your cat becomes irritable.
Dramatically decrease the amount of litter and collect the urine in a syringe before it is absorbed.
For litter boxes that have two levels, decrease the amount of litter in the top tray and take the absorbent pad out of the second one. Collect a sample from the urine accumulated in the tray.
Turn the absorbent pad upside down so it will urinate on the vinyl side.
Each day, your cat should intake the following amount of water:
This includes the amount of water found in food, for a total of one day's worth of drinking water.
The Appropriate Amount of Drinking Water
|If your cat eats dry food||90 - 170ml/day|
|If your cat eats wet food||5 - 85ml/day|
If your cat's main food is dry food and they drink over 200ml, or if it is wet food and they drink over 100ml, they are drinking too much water and may have kidney disease.
By putting water out at the same time every day, you will be able to see how much water your cat drinks each day. If your cat drinks over 200cc, they may have kidney disease or another disease, so please take it to an animal hospital for further testing.
Cats should drink fresh water. Mineral water and water with calcium ion or magnesium ion are not good for cats, as they may develop urinary stones. Water from a clean water source is best.
If your cat has been diagnosed with kidney disease, switch to medicinal food and give them medicine to prevent the disease from spreading. Although medicinal food is easier to eat than it used to be, if it doesn't suit your cat's tastes then they may get tired of it and refuse to eat it at times. If that happens, then you should look for alternative food that supports healthy kidney functions. We especially recommend wet food with a high water content.
Phosphorus is a mineral that is involved in the composition of cells and protein. 80% of phosphorus found in the body works with calcium as the bonding agents of bones and teeth. Try to keep an appropriate ratio of phosphorus and calcium, because if there is an overdose of phosphorus then the bones will leak calcium in an attempt to maintain the balance and the internal organs will calcify. Thus, it is important to maintain a balance of calcium and phosphorus.
Recommended calcium:phosphorus content: 1:1 ? 2:1
From “Small Animal Clininal Nutrition”
Sodium has a property that moves water with it, and regulates the amount of water in the body and blood pressure. It also preserves a certain amount of osmotic pressure in cells. It's also involved in nerve's information transmission. Unlike humans, cats do not sweat, so the amount of sodium they need is lower. Sodium intake should be restricted the same way phosphorus is.