Clinical symptoms of CKD

Clinical symptoms can occur at any stage of chronic kidney disease (CKD) and can be very individual. However, clinical symptoms are most common when uraemiaA raised level in the blood of urea and other urinary substances, which in chronic kidney disease can no longer be adequately excreted due to impaired renal function (glomerular filtration rate). This leads to renal damage due to uraemic toxins, toxic urinary substances The symptoms..., an accumulation of urinary substances such as uraemic toxinsToxic, nitrogen-containing urinary substances responsible for uraemia and kidney damage.... and ureaUrea is the nitrogen-containing breakdown product of protein metabolism. The nitrogen from the proteins is converted to ammonia in the liver, which is combined with carbon dioxide to form urea. This is continuously excreted via the kidneys but also via sweat. Urea is one of... in the blood, is already present. Uraemic toxins accumulate in many organs and cause damage there, which can lead to clinical symptoms. Uraemia can lead to urinary intoxication and is responsible for many of the symptoms associated with CKD. It usually occurs in the later stages of CKD, when the kidneys have already lost ¾ of their nephronsNephrone sind die Filtereinheiten der Nieren.....

There is no single clinical symptom (= cardinal symptom) that is unique to CKD. Each cat goes through CKD very individually. This also applies to the symptoms. The symptoms can develop gradually over weeks and months.

Increased drinking (polydipsia = PD)

PolydipsiaExcessive thirst due to illness, leading to excessive production of urine (polyuria).... (PD) = increased water intake of more than 100 ml per kg body weight per day.

Cats may try to drink from unusual water sources ( pots, toilet bowls, taps etc.). Increased drinking can therefore go unnoticed for a long time. Although cats drink more, they become increasingly dehydrated over the course of CKD as they lose water through urine because it can no longer be recovered by the damaged kidneys. Usually, around 99% of the filtered water is recovered and the urine is highly concentrated. This leads to small amounts of urine.

Increased urination (polyuria = PU)

PolyuriaExcessive production of urine, potentially due to kidney failure.... (PU) = high urine volume with more than 50 ml per kg body weight and day.

The increased urine excretion is associated with increased water intake. In CKD, cats lose the ability to concentrate urine and retain water. They therefore lose water via the urine and this increases the amount of urine. Increased urination can be observed particularly well in domestic cats by looking at the litter.

Loss of appetite/lack of eating

Loss of appetite (= inappetence) can have many causes: from inflammation of the mouth to inflammation of the stomach lining. But also dental problems, bad breath, an increase in uraemic toxins in the blood and lethargy. In any case, it is a prominent common symptom. CKD cats often have a very variable appetite during the course of the disease. They then no longer eat even their favourite food or only eat it poorly.

Vomiting

Vomiting is a frequent occurrence in CKD cats. It can appear from time to time during the different stages of CKD.

Bad breath (= halitosis)

Many cats have a prominent breath odour in the stage of uraemia. The mouth odour can then smell unpleasantly urine-like. This is caused by the exhalation of urinary substances such as uraemic toxins and urea, which accumulate in the mucous membrane of the mouth, as well as mouth ulcers, changes in the gastrointestinal tract or dental problems. Mouth odour can cause the cat to eat less well.

Fatigue / tiredness (= apathy) / sleepiness / inactivity

Many old cats are attributed sleepiness and fatigue as a symptom of old age. However, apathyIndifference, listlessness and lethargy can be an important symptom for recognising CKD.

Weight loss

Weight loss of 5% to 10% over several months can be a very early sign of CKD. As 5% weight loss in a 5 kg cat only shows up as 250 grams on the scales, you need correspondingly accurate scales. Appropriate scales such as baby scales, which are available in many veterinary practices, should be used to weigh the cat regularly.

Poor general condition, shaggy coat & loss of muscle mass

Cats with CKD not only lose weight, they also lose muscle mass. The cat often appears shaggier and sheds as CKD progresses. They may also show weakness and may stagger. Overall, the general condition continues to deteriorate as the disease progresses.

Plantigrade gait

A particular symptom of CKD cats is the plantigrade gaitA “bear-like” gait. Cats walking with a plantigrade gait don’t walk on their paw tips, but with their metatarsal bones and hocks (ankles) on the ground. Typically occurs in cats with diabetes...., in which the cats walk on their hocks. This looks like a weakness of the hindquarters or a rabbit gait. The cause of the plantigrade gait is nerve damage due to an accumulation of phosphate in the blood (= hyperphosphataemiaIncreased phosphate in the blood.). If the phosphate blood level is lowered, the cat usually walks normally again. A plantigrade gait can also occur in connection with diabetes.