As pet owners, we've all grown up hearing about the importance of calcium for strong bones and overall health. Calcium is a mineral that plays a vital role not only in bone structure but also in the proper functioning of muscles, including the heart. It acts as a messenger in various biochemical processes, regulating numerous bodily functions. In both humans and our furry companions, calcium is carefully monitored through regular blood tests, as maintaining the right balance is crucial.
The Role of Calcium in the Body
Calcium exists in different forms within our bodies, depending on whether it's actively being used or stored.
Ionized calcium is the form that circulates freely in the bloodstream and is readily available for various bodily functions. It's tightly regulated because too much or too little can be dangerous. Roughly half of blood calcium is ionized calcium.
Bound calcium, on the other hand, is still circulating in the blood but is bound to molecules like albumin or complexed with other ions. This form of calcium doesn't float around freely. Approximately 40% of blood calcium is bound.
The total calcium level, which is reported in most blood chemistry panels, combines both ionized and bound calcium. This value represents the total calcium in the bloodstream, not in the entire body.
Furthermore, calcium is also stored in our bones, serving as a reservoir that can be tapped into when the body requires additional circulating calcium. When the body needs to raise blood-ionized calcium levels, it can draw from bone stores or enhance calcium absorption from the intestines.
Regulating Calcium Levels
The regulation of calcium levels in the body is orchestrated by two hormones: parathyroid hormone (PTH) and calcitriol (vitamin D). These hormones work in tandem to control calcium levels.
When blood-ionized calcium levels decrease, the parathyroid glands release PTH, which in turn raises ionized calcium levels by promoting the release of calcium from bones and reducing calcium excretion by the kidneys. Simultaneously, calcitriol activates to increase calcium absorption from the intestine, further elevating ionized calcium levels.
Conversely, when blood calcium levels rise too high, calcitriol stops PTH production in the parathyroid glands, leading to a drop in ionized calcium levels.
Signs of Hypocalcemia (Low Blood Calcium)
Hypocalcemia, or low blood calcium, can lead to a range of symptoms. Without sufficient calcium, muscle contraction becomes abnormal, and the nervous system becomes more excitable. In severe cases, it can lead to a condition called hypocalcemic tetany, characterized by seizures.
Common signs of hypocalcemia in pets include:
- Nervousness
- Disorientation
- Unsteady gait (drunken walk)
- Fever
- Weak pulses
- Excessive panting
- Muscle tension
- Twitches and tremors
- Listlessness (more common in cats)
- Raised third eyelids (more common in cats)
- Painful muscle cramping, which can lead to aggression
- Death in severe cases (calcium levels drop to 4 mg/dl or below)
Causes of Hypocalcemia in Pets
Hypocalcemia in pets can result from various underlying causes. Here are some common culprits:
- Small Mothers Nursing Large Litters: When a small mother dog nurses a litter of puppies that's too large for her, she can become depleted in calcium. This condition is typically evident in a female dog nursing a litter, and treatment involves calcium injections followed by oral supplements.
- Chronic Renal Failure: Kidney disease can disrupt calcium balance, causing either high or low calcium levels. Proper management depends on controlling phosphorus levels and requires blood and urine tests to assess kidney function.
- Acute Pancreatitis: Inflammation of the pancreas can lead to severe nausea, diarrhea, and pain. As the body digests fats, it releases triglycerides that bind to blood calcium, driving ionized calcium levels down. This can result in hypocalcemia.
- Toxins: Certain toxins, such as human phosphate-based enemas or ethylene glycol (antifreeze), can cause hypocalcemia in pets. These substances should never be used to treat constipation without veterinary guidance.
- Parathyroid Hormone (PTH) Deficiency: This condition, although not common, is a classic cause of hypocalcemia. When there's insufficient PTH, calcium levels remain low, and vitamin D is not activated. Affected pets typically require lifelong treatment and monitoring.
Diagnosis of Hypocalcemia
Diagnosing hypocalcemia involves a combination of history, physical examination, and blood and urine tests. It's essential to rule out other potential causes of low blood calcium, such as low albumin levels, kidney failure, pancreatitis, or exposure to toxins.
A comprehensive blood panel and urinalysis help differentiate between hypoparathyroidism and other conditions. Additional tests, like measuring PTH levels and magnesium levels, may be necessary to confirm the diagnosis.
Treatment of Hypocalcemia
Treatment for hypocalcemia depends on the severity and underlying cause. Here are some key aspects of treatment:
- Hospitalization: Severe cases with seizures or dangerously low calcium levels may require hospitalization for intravenous calcium administration.
- Oral Calcium and Vitamin D Supplementation: Once stable, pets can be started on oral calcium and vitamin D supplements. The response to these medications may take several days. In some cases, calcium injections may be necessary initially.
- Types of Vitamin D: There are different forms of vitamin D used for long-term management, including Vitamin D2, DHT (Dihydrotachysterol), and Vitamin D3 (Calcitriol). Calcitriol is often the preferred choice due to its faster onset of action and effectiveness.
- Oral Calcium Supplements: Calcium supplements are available in various forms, but calcium carbonate is often the preferred choice. Changing the type of calcium supplement should only be done under veterinary guidance to ensure proper dosing calculations.
Monitoring and Prognosis
Monitoring calcium levels is crucial in managing hypocalcemia. The goal is to keep calcium levels within the normal range (8-9 mg/dl or 2.0-2.25 mmol/L). Stable patients with hypoparathyroidism should undergo quarterly calcium level checks to ensure proper treatment and dosage adjustments.
Pet owners should be vigilant for signs of elevated calcium levels, such as vomiting, diarrhea, excessive water consumption, or listlessness, as these can indicate overdose. If calcium levels become too high, prompt veterinary attention is necessary to avoid complications.
In conclusion, hypocalcemia can be a challenging condition, but with proper diagnosis, treatment, and monitoring, pets with this disorder can lead healthy and happy lives. If you suspect your pet may have low blood calcium, consult your veterinarian for a thorough evaluation and tailored treatment plan. Remember, maintaining the right balance of calcium is essential for your pet's well-being, just as it is for us humans.
Don't have a vet in your area yet? We can help you find a local veterinarian.
If you have more questions, the GeniusVets Telehealth platform will give you unlimited access to text and/or video calls with board-certified veterinarians! To learn more click here.