![Jordan Hampel](/sites/default/files/images/media/image/VF_333_Article_7_GB_Hampel_Jordan.png)
Get access to all handy features included in the IVIS website
- Get unlimited access to books, proceedings and journals.
- Get access to a global catalogue of meetings, on-site and online courses, webinars and educational videos.
- Bookmark your favorite articles in My Library for future reading.
- Save future meetings and courses in My Calendar and My e-Learning.
- Ask authors questions and read what others have to say.
Pathologic hypercalcemia in the dog
Get access to all handy features included in the IVIS website
- Get unlimited access to books, proceedings and journals.
- Get access to a global catalogue of meetings, on-site and online courses, webinars and educational videos.
- Bookmark your favorite articles in My Library for future reading.
- Save future meetings and courses in My Calendar and My e-Learning.
- Ask authors questions and read what others have to say.
Read
This paper looks at differential diagnoses and therapeutic management options when a dog is found to have elevated calcium levels.
Jordan M. Hampel
DVM, Department of Veterinary Clinical Medicine, University of Illinois at Urbana-Champaign (UIUC), Illinois, USA
Dr. Hampel received her Doctor of Veterinary Medicine from the University of Illinois in 2020 and then went on to complete a rotating small animal internship at Michigan State University. She returned to the UIUC to further advance her training as an oncology-dedicated clinical trial intern, and is currently a resident in Medical Oncology and pursuing a Master of Science degree that focuses on targeted strategies to amplify the cytotoxic activities of ionizing radiation therapy.
![Jordan Hampel](/sites/default/files/images/media/image/VF_333_Article_7_GB_Hampel_Jordan.png)
Timothy M. Fan
DVM, PhD, Dip. ACVIM (Oncology, Internal Medicine), Department of Veterinary Clinical Medicine, University of Illinois at Urbana-Champaign, Illinois, USA
Dr. Fan received his DVM from the Virginia-Maryland Regional College of Veterinary Medicine in 1995 and continued training to become board-certified in Small Animal Internal Medicine and Oncology at Cornell University and UIUC, respectively. He then completed a PhD focusing on tumor immunology at Illinois, and joined the faculty where he is professor, a core member in the Anticancer Discovery from Pets to People theme, and a program leader for the Cancer Center at Illinois that includes companion animals as sophisticated models to study cancer.
![Fan T.](/sites/default/files/images/media/image/vf-333-article-7-gb-fan-timothy.png)
Key points
- Calcium homeostasis is tightly regulated by parathyroid hormone, calcitonin, and vitamin D, which primarily affect calcium mobilization, excretion, and absorption at skeletal, renal and intestinal tissues, respectively.
- The most common causes of hypercalcemia in dogs are cancer, primary hyperparathyroidism and hypoadrenocorticism; idiopathic hypercalcemia – commonly seen in cats – is less common in dogs.
- Clinical signs of hypercalcemia include primary polyuria with secondary polydipsia, generalized weakness, lethargy, gastrointestinal disturbances and weight loss.
- Prompt medical intervention to enhance calciuresis with identification and treatment of the underlying cause for the hypercalcemia are critical for optimal patient management and a favorable outcome.
Introduction
Calcium is the fifth most abundant element in the body, existing as an essential cation found within bodily fluids and also stored within cellular organelles. It is responsible for many vital intracellular and extracellular functions, including neuromuscular transmission, enzymatic reactions, blood coagulation, vasomotor tone, hormone secretion and bone metabolism. While calcium is broadly distributed throughout cellular tissues, rapid fluctuations in intracellular calcium serve as a primary regulator of cellular responses following plasma membrane receptor activation, and it also serves as a secondary messenger responsible for perpetuating external signals into cells to orchestrate downstream biologic functions (1).
While intracellular calcium is critical for normal cellular activities, the clinical measurement of calcium is restricted to its presence in body fluids where it exists in three different forms, namely ionized, protein-bound, and complexed with anions or organic acids. Ionized calcium (iCa) is the biologically active form that can pass through plasma membranes by virtue of permeable ion channels, active transporters and cation exchangers (2), and comprises 50% of total serum calcium. The remaining fraction is approximately distributed as 40% protein-bound and 10% complexed. Given its importance in cellular functions, iCa concentrations must be tightly regulated to ensure proper physiologic activities of a myriad of cellular, tissue, and organ systems; this is done through the concerted actions of parathyroid hormone (PTH), 1,25-dihydroxycholecalciferol (active vitamin D3 or calcitriol) and calcitonin (3). Similar to its importance for intracellular signaling, calcium within extracellular fluid also regulates cellular functions of many vital glandular and epithelial tissues, including the parathyroid gland, thyroid C cells, and kidney.
Calcium homeostasis
The three principal mediators, PTH, calcitonin, and calcitriol, are responsible for balancing whole-body calcium concentrations through the exertion of complementary and/or synergistic biologic activities on three target organs, namely the kidneys, small intestines, and inorganic bone matrix (hydroxyapatite) (3)(Figure 1).
![vet focus journal 333 mechanism of calcium homeostasis](/sites/default/files/images/media/image/vf-333-article-7-gb-figure-1.jpeg)
Figure 1. Mechanism of calcium homeostasis. The three principal mediators that balance whole-body calcium concentrations (PTH, calcitonin and calcitriol) can exert complementary and/or synergistic biologic activities on three target organs, namely the kidneys, small intestines, and inorganic bone matrix (hydroxyapatite). On the parathyroid cell surface, the calcium receptor senses fluctuations of extracellular calcium. In situations of hypocalcemia, PTH increases serum calcium levels through enhanced bone resorption and renal calcium reabsorption. PTH indirectly contributes to calcium absorption within the small intestine through the conversion of vitamin D to highly active vitamin D3 (calcitriol) in the proximal renal tubules through the upregulation of 1-alpha-hydroxylase activity.
© Redrawn by Sandrine Fontègne
[...]
Get access to all handy features included in the IVIS website
- Get unlimited access to books, proceedings and journals.
- Get access to a global catalogue of meetings, on-site and online courses, webinars and educational videos.
- Bookmark your favorite articles in My Library for future reading.
- Save future meetings and courses in My Calendar and My e-Learning.
- Ask authors questions and read what others have to say.
About
How to reference this publication (Harvard system)?
Author(s)
Copyright Statement
© All text and images in this publication are copyright protected and cannot be reproduced or copied in any way.Related Content
Readers also viewed these publications
Subscribe
Access to the content of the Veterinary Focus website is reserved for animal health professionals. If you do not yet have a user account with Royal Canin you can create a free account by selecting the New User form. Subscription to the journal is free and issues in your preferred language can be obtained at the Veterinary Focus website.
![Royal Canin](/sites/default/files/images/media/image/hero2_0.png)
Comments (0)
Ask the author
0 comments