Phosphorous In Cats And What It Means For Pet Parents

Phosphorus is a mineral used in important functions in the body and, in the case of a cat it is bonded with calcium to form calcium phosphate. Calcium phosphorus is used in creating healthy teeth
and bones within the cat. The phosphorus which is not used by the bones and teeth is used to help maintain nerves and muscles.

Too much phosphorus in a cat is not always noticeable as the symptoms are much more subtle. As a cat ages, its body may begin to produce too much phosphorus. Kidneys of cats with Chronic

Kidney Disease no longer remove excess phosphorus from the cat’s body. When a cat has too much phosphorus they develop a condition called hyperphosphataemia.


  • Loss of Appetite: The loss of appetite in a cat can lead to other problems in addition to hyperphosphataemia. When it is discovered the cat is not eating, the issue must be addressed within 24 hours. In the case of young kittens, the response time must be shorter, 12 hours. When a cat is not eating, they may not be drinking, either and this can lead to dehydration. General speaking, loss of appetite in a cat is a warning sign of trouble and should be taken seriously.
  • Itching: Itching can be caused by toxins in the cats blood and is also a sigh of too much phosphate. In addition, it can be a sign of liver problems or simply too little vitamin B, a fatty acid deficiency or a side effect to hyperthyroidism medication. Blood work performed by a veterinarian is a good way to find out why the cat is itching.
  • Lack of Co-ordination in the Limbs/Back Leg Weakness: A lack of coordination in limbs or back leg weakness can be due nerve messages being disrupted by high phosphorus levels. This condition is known as nephropathy. Notable symptoms of this condition include a cat getting up without raising their hind legs, as if forgetting about them. Another indication of this condition is stumbling on their own four feet.
  • Plantigrade Posture: More common in diabetic cats, a plantigrade posture is where a cat will walk on their hocks, rather than their feet. Not only is this a sign of low phosphorus levels, but it can indicate significant neurological problems.
  • Teeth Grinding: Teeth grinding is another symptom which may have other reasons, usually as a way to get through the pain of some other health issue. Excess stomach acid will cause it. Oral cavity are often the problem, in addition to tooth resorption or disintegration, inflammatory gum disease, ulcers in the lining of the cat’s mouth, bad alignment of the teeth. It can also be the result of pain from abdominal diseases like pancreatitis, inflammatory bowel disease, cancer, and gastrointestinal ulcers. Additionally, brain and behavioral disorders cause teeth grinding.
  • Knuckling: If a cat is knuckling or knucklewalking, they have balled up their paws and are walking on them.
  • Weakness: Weakness in the muscles, particularly the back muscles can be the result of several problems. The cat may be deficient in certain vitamins and minerals. They could have too much phosphorus in their system. This can also be an indication of serious heart problems and will require the attention of a vet.
  • Weight Loss: Note, there may be other reasons for a cat losing weight quickly. These reasons can include proteinuria or metabolic acidosis, diabetes or hyperthyroidism. Other reasons could be causes include IBD (Inflammatory Bowel Disease) or cancer.
  • Nausea: High phosphorus levels and secondary hyperparathyroidism it may cause may result in nausea, which may be manifested as a lack of appetite. Anaemia or metabolic acidosis may also cause nausea.
  • Twitching, Trembling or Shaking: Twitching may be caused by high phosphorus levels. It can also be a symptom for other conditions.

Why does it get out of control?
Kidney disease is often seen at the main cause of hyperphospatemia. The kidneys are used to filter the blood of the cat and are supposed to be able to filter out the excess phosphorus for disposal.
There are other causes, though including bone disease, cancer, hyperthyroidism, calcium deficiency or improper diet. If any of the above symptoms are displayed, it is important to get the cat to a
veterinarian as soon as possible for examination.

Once there, the veterinarian will begin to look at the cat’s age and history. The age of the cat is significant, as older cats have a tendency to develop chronic health problems as they age. Younger
cats, meanwhile are at risk for ingesting poisons which can do enormous damage if it does not kill them.

The veterinarian will ask the owner a variety of questions, to try to determine what the cat’s diet and daily life is like. They will ask questions regarding the above mentioned symptoms as well, such as

the cat’s eating habits, thirst, lack of energy, vomiting, tremors or twitching. Then, they will conduct blood and urine tests, as well as bone and kidney x-rays. The blood and urine samples will also show
any evidence of thyroid malfunction and diabetes. Bone X-rays can show abnormalities such as cancer, tumors or osteoporosis, while kidney x-rays will reveal any abnormal changes to the kidneys.

Hyperphosphatemia occurs when there is imbalance between calcium and phosphate available. This will cause a progression of chronic kidney disease in the cat. This imbalance can be caused by a

number of things; kidney disease, kidney infection, hyperthyroidism, urinary tract blockage, bone cancer and other things.

Ways to Control High Phosphorus Levels

Once phosphorus levels are determined to be the problem, the objective becomes controlling the levels in the cat. There are several ways to do this.

  • IV fluids may be administered by the veterinarian to bring the levels back into balance and to restore electrolytes. Depending on what else is wrong, the veterinarian may prescribe other therapies.
  • Kidney disease: A diet high in protein and low in phosphorus will be prescribed, though chronic kidney disease has no cure. Aluminum hydroxide or calcium citrate may be added as supplements to bind to phosphorus so that it can be safely excreted. This would be given under veterinarian supervision.
  • Hyperthyroidism: If detected, the veterinarian will prescribe medications related to this condition. Having the right hormone levels will prevent hyperphosphatemia as well as other conditions such as osteoporosis, bone tumors and bone cancers.

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