Bella’s story is one that highlights how important calcium is for a normal functioning body.

Bella visited us earlier this year because she was having episodes of cramping in her back legs. The cramps would appear out of nowhere and weren’t clearly triggered by anything — sometimes occurring at rest, other times during exercise. Initially it was happening a few times per week but increased to multiple times per day. It was distressing for Bella, causing her to vocalise which raised concern that she might be in pain. She was also increasingly lethargic and slow on her walks which was very out of character for a usually very bouncy and energetic Border Collie.

Bella’s owners had taken some videos of the episodes which helped us to assess what they were observing at home. After assessing Bella, we decided to run some diagnostic tests, starting with a blood sample to assess her general health and look for possible inflammatory or infectious disorders. The blood tests revealed low ‘total calcium’ levels but were otherwise unremarkable, so to check this wasn’t a sampling or handling error, we rechecked the ‘total calcium’ levels alongside ‘ionised calcium’, and both were significantly lower than normal.

Calcium plays many important roles at a microscopic level within the body and one of these is involvement in the process of muscle contraction. When calcium levels are low, the nerves supplying the muscles become over-excited resulting in muscles that cannot contract and relax properly, leading to weakness and cramping.

Once we had confirmed that Bella had low calcium levels, we needed to find out why. Because calcium is very important in multiple processes in the body, it is usually tightly regulated by the body itself (a process called ‘calcium homeostasis’) so that, despite variations in diet and lifestyle, calcium levels remain within a normal range. Calcium homeostasis is complicated but in short, it is controlled by a five key players; parathyroid hormone, vitamin D, the kidneys, the bones and the intestines.

We checked Bella’s blood levels of parathyroid hormone (PTH), which in usual circumstances should be present in high levels in the blood when working against low blood calcium levels. It’s PTH’s job to increase calcium levels when they drop by absorbing additional calcium from the food in the intestines and releasing it from storage within the bones. Bella’s parathyroid hormone levels were also low, leading us to a diagnosis of ‘hypoparathyroidism’. Hypoparathyroidism can occur for two main reasons, immune-mediated damage to the parathyroid gland, which sits next to the thyroid gland in the neck, and surgical removal of the parathyroid gland. We knew Bella hadn’t had surgery, so we were able to diagnose her with immune mediated hypoparathyroidism, also known as primary hypoparathyroidism.

Thankfully treatment for primary hypoparathyroidism is relatively straightforward and involves correcting the calcium levels by supplementing calcium and vitamin D. Of course, there’s a risk of over-supplementing, which could result in too much calcium in the blood which is also very problematic, so careful monitoring is essential both short and long term. Bella spent the day with us receiving an intravenous calcium infusion, she was closely monitored by our nursing team, with her blood calcium levels checked throughout the day. She was then discharged home to her owners to continue with oral calcium and vitamin D supplements.

Within the first 24 hours the cramping episodes stopped, and we were thrilled to learn that within a couple of weeks, Bella slowly returned to her usual active self.

Once Bella’s calcium levels were within the normal range, we reduced her treatment to just the vitamin D supplement as her regular dog food should provide sufficient calcium, and we want to avoid the risk of over-supplementation. Bella will live with this condition for the rest of her life, so she will need health checks and blood samples periodically to check her calcium levels are appropriate, but she is now able to live a normal life again we are all delighted with her progress so far.