What is Hypocalcemic Tetany?
Tetany is a disorder which is caused by a variety of underlying conditions. This disorder presents itself as muscle spasms that come and go. Hypocalcemic tetany in horses is a health condition in which the parathyroid glands are not functioning properly and the horse’s body has a calcium deficiency. Hypocalcemic tetany in horses is a rare disorder caused by low amounts of ionized calcium and possibly phosphate and magnesium.
Because calcium is essential for the health of cells, there are negative effects when there is a deficiency of this macronutrient. The skeleton of the horse contains most of the calcium, which gives the body the support it needs for mechanical purposes as well as maintains an extensive amount of stored calcium. Stored calcium is essential in providing the positive ions the body needs. Calcium is also found in the non-skeletal regions of the body and is protein-bound, within the ionized or free state, or complexed. When a horse has abnormally low amounts of ionized calcium within the body, he may acquire the condition known as hypocalcemia.
Hypocalcemic tetany in horses is a result of a significant calcium deficiency, which causes various side effects, including muscle spasms, tremors, and convulsions.
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Symptoms of Hypocalcemic Tetany in Horses
Symptoms of hypocalcemic tetany in horses can range from moderate to severe. Symptoms can become quite severe within 48 hours, so immediate medical attention is necessary. Symptoms of this rare disorder include:
- High fever
- Muscle contractions
- Muscle tone increase
- A stiff gait
- Tremors of the muscles
- A prolapsed third eyelid
- Difficulty chewing
- Heart arrhythmia
Upon performing a physical examination of your horse, your veterinarian will need to perform tests exclusive to hypocalcemic tetany to avoid any differential diagnoses. Other types of disorders that present similar symptoms include:
- Seizure disorder
- Exertional rhabdomyolysis
- Other muscle disorders
Causes of Hypocalcemic Tetany in Horses
There are several causes of hypocalcemia, which may lead to hypocalcemic tetany. Causes include:
- A decrease or lack of absorption of calcium from intestines
- Gastrointestinal tract disease or illness
- Significant decrease of calcium from sweat, the kidneys, or milk in lactating mares
- Changes in the parathyroid hormone
- Degeneration of bone tissue (osteolysis)
- A great amount of milk production in lactating mares
- Excessive physical activity
- The inhibition of Vitamin D
- Ingestion of blister beetles
Diagnosis of Hypocalcemic Tetany in Horses
If your horse is exhibiting any signs or symptoms of hypocalcemic tetany, make an immediate appointment with your equine veterinarian. It is important to see the veterinarian as soon as possible, as symptoms can increase quite rapidly.
The veterinarian will look closely at your horse’s clinical signs and medical history. In terms of clinical signs and symptoms, he will be looking for the classic symptoms of tetany, such as muscle tremors, stiffness, abnormal gait, high fever, and any other symptoms relative to your horse’s possible condition. He may ask several questions pertaining to his physical activity, or, if your horse is a female that has recently given birth, he will want to know information concerning her lactation and how much milk she is producing. He may also want more information about your horse’s diet, physical activity, and the severity of the symptoms he is experiencing.
In order for the veterinarian to come to a definite conclusion of hypocalcemic tetany, he will need to perform a few laboratory tests. He will test the serum levels of the ionized calcium within your horse, as abnormally low levels may point to a diagnosis of hypocalcemic tetany. He will measure the ionized calcium concentration,and any dietary deficiencies or imbalances by way of a biochemistry profile which will test for calcium and phosphorus amounts. He will also test for increased amounts of urinary phosphorus and decreased amounts of your horse’s concentration of urinary calcium.
Treatment of Hypocalcemic Tetany in Horses
Once your veterinarian has come to the conclusion that your horse’s tetany has been the result of a significant deficiency of calcium, he may perform the following methods of treatment.
There are various solutions which can relieve the horse from this condition. The amounts of solutions within the IV as well as the specific types of solutions will be determined by the severity of your horse’s condition. The veterinarian may administer calcium borogluconate or other types of calcium solutions and may possibly give a second dose. Many horses needed repeated dosages to recover, and this may take several days. IV fluids are also beneficial in hydrating your horse as well.
Your veterinarian may suggest implementing feed with higher amounts of calcium, such as alfalfa or legume hay.
Analgesics to help your horse with muscle pain may help ease the discomfort. Your veterinarian may prescribe a broad-spectrum antibiotic to help with any bacterial infection your horse may have as well.
Your veterinarian will need to monitor your horse for a few days or longer to be sure he is responding to treatment. With hypocalcemic tetany, there is a possibility for relapse, so closely monitoring him will need to be continued after your horse is released back to your care.
Recovery of Hypocalcemic Tetany in Horses
Your veterinarian will explain what you need to do to take care of your horse once treatment is complete. He will advise you as to what symptoms to watch for, and he will want to see him for follow-up visits. As part of his treatment, your vet may have recommended increasing his calcium intake. Be sure to provide feed that has more calcium, especially if your horse is a lactating mare. The feed needs to contain enough calcium and phosphorus at proper ratios. If you are unsure as to what to feed your horse, your veterinarian can recommend a proper diet and feed.
When transporting your horse, be sure to minimize stress. If your horse performs any physical activity that requires endurance, be sure to supplement his diet with electrolytes and give plenty of fresh water. If you notice your horse is having any new symptoms or signs of relapse, do not hesitate to contact your veterinarian.