What factors reduce the level of calcium absorption that occurs within the diet?
- High fat diets
- Phytates and oxalates
- High Ca intake
- Very high or very low levels of potassium
- Vitamin D deficiency
+ also occurs more often within older animals
What are some clinical symptoms from a calcium deficiency?
- Bone defects (Rickets in young animals + osteomalacia (older animals) + NSH
- Soft beaks and thin egg shells
What are the three bone disorders that arise from a calcium deficiency in the diet?
- Rickets
- Osteomalacia
- NSH (nutritional secondary hyperparathyroidism)
What are the conditions that occur in the diet as a result of hypocalcaemia?
- Milk tetany
- Hypocalcaemia
- Thumps/SDF or myopathies in horses
What are the causes of hypocalcaemia in cattle, dogs and cats?
- Early lactation
2. Oestrogen
What are the causes of hypocalcaemia in sheep?
- Late pregnancy
2. Off feed
What are the causes of hypocalcaemia in horses?
- Heavy sweating
2. Transport
What is the treatment for hypocalcaemia?
Calcium (eg. calcium borogluconate) given slowly intravenously
What are the actual causes of hypocalcaemia in cattle around the time of calving?
- Ca loss in colostrum beyond the capacity of Ca absorption from gut and mobilisation from tissues
- Impaired Ca absorption from gut around calving due to reduced feed intake
What is the delay time for the action of calcitriol?
Delay of about 16 to 24 hours
What is the effect of over supplementation of calcium within the diet?
The over-supplementation of calcium impairs PTH secretion. Low PTH causes poor Ca absorption from gut and bone this leads to poor reabsorption in the kidney.
What is the effect of low magnesium in the diet and what is the significance of it?
Low plasma Mg reduces PTH and hence calicfitriol production. Hence both hypocalcaemia and hypomagnesaemia both occur concurrently
Complete the statement below:
Plasma Ca falls faster when diet K is _(high/low/adequate)______
high
What are the three clinical stage signs in cattle?
Stage 1: excitement/tremors
Stage 2: Sternal recumbency
Stage 3: lateral recumbancy
What is the best diagnostic test for hypocalcaemia?
Response to treatment with calcium
What other treatments can be given to animals with hypocalcaemia?
- Anti-inflammatory for muscle soreness
- P and Mg may be necessary for animals in complicated cases
- Nursing care necessary for animals remaining down after treatment
What treatment options are available for preventing relapse of hypocalcaemia?
- Oral salts given subcutaneously
- Oral calcium chloride
- Manage further Ca losses
How can periparturitient hypocalcaemia be managed?
- Decrease the dietary calcium prior to parturition
- Feed a DCAD transition diet (acid-base)
- Provide Vitamin D supplements in diet
What is the goal of a DCAD diet and how does this limit metabolic acidosis?
A transition diet aims to induce a mild metabolic acidosis. This results in a negative DCAD that improves gut absorption and improves bone reabsorption of Ca by osteoclasts.
What ions will increase the DCAD of the diet?
Na and K
What ions will decrease the DCAD of the diet?
Cl and S
What dietary factors contribute to hypocalcaemia within sheep?
- Grazing of cereal crops (low Ca)
- Oxalate pastures (bioavailability)
- Reduced feed intake
- Mostly affects pregnant ewes
What are some factors that will predispose dogs to hypocalcaemia?
- High meat diets
2. Lactation - large litters and in small breeds
What are the causes of hypocalcaemia within horses?
- Stress
- Ca and Mg lost in sweat
- Alkalosis
