Low Blood Calcium in Cats

When blood calcium levels are low, cats and other companion animals may exhibit symptoms that indicate issues with the bodily systems that require calcium for proper function. Muscle issues and neurological issues are the most common, although they may not be noticeable in mild or moderate cases. If symptoms are observed, seek medical attention immediately, as severe calcium deficiency in the blood can be life-threatening.

Low blood calcium, medically referred to as hypocalcemia, is a medical condition that occurs when the levels of calcium in an animal’s blood drop below acceptable levels. Calcium is an essential nutrient used in many bodily functions, including bone growth, bone health, muscle contraction, blood clotting, nervous system function, and more. Low blood calcium is also often linked to low vitamin D levels, high phosphate levels, and insufficient levels of parathyroid hormones. 

When blood calcium levels first begin to drop, or in cases which levels are only mildly or moderately low, many cats will not exhibit any visible symptoms. It is possible for low blood calcium to be noted in a blood test even in cats that are asymptomatic. If levels remain low for an extended period, or in more severe deficiencies, cats and other companion animals may exhibit symptoms. 

Symptoms include:

• Weakness
• Vomiting
• Lack of appetite
• Lying with limbs rigidly extended
• Stiff-legged gait
• Trouble walking
• Panting or rapid breathing
• Dilated pupils
• Irritability
• Restlessness
• Depression
• Confusion or disorientation 
• Hypersensitivity to touch or sound
• Face rubbing or signs of facial itchiness
• Uncontrolled muscle contractions
• Twitching
• Muscle tremors
• Seizures
• Death

Low blood calcium in cats can be caused by several conditions. It generally occurs either because calcium supplies are deficient, phosphate levels have climbed, or there is poor performance of the parathyroid gland. Hypocalcemia is fairly common in cats that have had their parathyroid gland removed. Some of the common causes of low blood calcium in cats include:

• Post removal of the parathyroid gland
• Kidney disease or kidney failure
• Parathyroid tumor
• Hypoparathyroidism
• Postpartum eclampsia
• Poor nutrition during pregnancy
• Hypoproteinemia or low blood protein
• Hypomagnesaemia or low blood magnesium
• Pancreatitis
• Rickets
• Certain medications
• Antifreeze or other similar poisonings 
• Toxicity from citrate or oxalate
• Extreme lack of calcium in diet or malnutrition

Several medical conditions can cause symptoms similar to those that occur due to low blood calcium. Part of the diagnostic process will involve ruling out other conditions. Diagnostic testing may be fairly extensive, even once low calcium has been identified. This is necessary to determine if the underlying cause is a failure of another internal organ or system. Your veterinarian will need to discuss your pet’s medical history, and symptoms you have observed, and the timeline associated with those symptoms. This will help them identify likely causes of your cat’s symptoms. A routine physical examination will also be conducted. Blood and urine samples will be collected for laboratory testing as well. 

Generally, low blood calcium is confirmed during a blood test. Low calcium levels and high phosphate levels will indicate blood calcium is a concern. Your veterinarian will also test for parathyroid hormones and parathyroid function if your pet still has their parathyroid gland. Urine samples may also be tested, with a focus on kidney function. Additional testing will be focused on kidney function, pancreatic function, and parathyroid function, as issues with these vital systems are most likely to cause low calcium levels. In some cases, diagnostic imaging techniques may be used. This could include x-rays, ultrasounds, or other similar methods. 

The main focus of treatment for low blood calcium will be returning calcium levels to a normal range. If your cat’s levels are extremely low, this process will involve hospitalization. While your pet is hospitalized, blood calcium levels will be closely monitored. Heart monitoring is also required because there is some risk of heart-related issues when calcium levels are being increased. This is commonly accomplished using an electrocardiogram. Common treatment methods include:

Calcium Supplementation 

Calcium will be supplemented to increase the levels of blood calcium. In serious cases, this will occur through injection or through the use of intravenous fluids. Supplementation will often include vitamin D to help the cat better absorb the calcium. Depending on the underlying cause of your pet’s condition, supplementation may be continued on a long-term basis. Once released from the hospital, supplementation is generally provided on an oral basis. 

Treatment for Poisoning or Toxicity

If antifreeze poisoning or other sources of toxicity are confirmed, related treatments will be provided. Your pet will be hospitalized during and post-treatment to ensure a successful recovery. Common treatments for poisoning include induced vomiting, stomach lavage, and administration of medications to counteract the toxin. There is a low risk associated with these treatment methods. 

Treatment for Kidney Disease

If kidney disease or kidney failure is identified, appropriate treatments will be provided. This may include dialysis and medications. In some cases, kidney failure is untreatable. 

Surgical Removal of the Parathyroid 

If the parathyroid gland presents with a tumor or is causing hypoparathyroidism surgical removal may be needed. Your pet will be hospitalized for surgery and recovery. As with any surgical treatment, there is a moderate risk associated with this procedure. Your cat may still require calcium supplementation post-surgery. 

Prognosis will depend on the underlying cause of low blood calcium levels. In most cases, if proper treatment is received, the prognosis is good. Supplementation with calcium and vitamin D may be required on a long-term basis and administered at home. Dietary changes may also be recommended and should be followed to ensure a successful recovery. It should be noted that if low blood calcium occurred during pregnancy or postpartum, it will likely occur with subsequent pregnancies. Extra care should be taken if the cat becomes pregnant in the future. Be sure to follow all of your veterinarian’s instructions, including proper dosing of medication and supplements and returning for any requested follow-up visits.