Oorsig/Review
8. POORLY
AUDIBLE
(RAPID)
HEART BEAT
2. FLEXED
NECK OR
TORTICOLLIS
9. SHALLOW
BREATHING
10. RUMEN
STASIS
7. MYDRIASIS,
DRY CORNEA
6. CYANOSIS
15. URINE
RETENTION
5. DULL
EXPRESSION
4. DRY
MUZZLE
3. COLD
EXTREMITIES
Subclinical hypocalcaemia – the number
1 metabolic disease of dairy cows
A lot of the economic value in prevention
of hypocalcaemia at parturition lies in the
prevention of subclinical hypocalcaemia and
not so much in the prevention of clinical milk
fever. It has, for instance, been demonstrated that
diets that were designed to prevent peri-partum
hypocalcaemia, increased milk production by 350
- 480kg/cow in the lactation. One can also expect
a significant improvement in the conception rate
and other reproductive parameters, a reduced
incidence of retained placenta and a reduction in
the number of cases with udder oedema. It may
thus prove to be a good idea to institute steps
to prevent milk fever, even in herds where the
incidence of the condition is less than 5%.
Non-parturient hypocalcaemia
Occasionally hypocalcaemia with typical “milk
fever” signs occurs in cattle (dairy or beef) at
other times than the typical post-parturient
presentation. This may be seen as individual
cases or even as outbreaks, and the following
factors, or combinations of these, may play a role:
1. Conditions that lead to a reduction in dry
matter intake that lasts for 12-16 hours:
Oestrus, bad weather, other disease
conditions such as mastitis/metritis/LDA/
rumen acidosis etc.
2. Dietary factors such as reduced Calcium or
Magnesium in the feed, vitamin D deficiency
or plants containing Oxalate that binds
available Calcium. The feeding of chicken
manure is a risk factor.
3. Conditions leading to a metabolic alkalosis
such as LDA, dietary intake of rations high in
Potassium or protein.
24
11. RUMEN
TYMPANY 12. LOW
RECTAL
TEMP
14. CONSTIPATION
13. BULGING
PERINEUM
1. FLACCID
PARALYSIS
4. Kidney failure leads to ongoing loss of
Calcium and reduced intestinal uptake
despite deficiency (vit D deficiency). This
presents as an unresponsive hypocalcaemia.
5. Conditions that lead to endotoxaemia
cause Ca to be moved into the intracellular
compartment, also leading to an unresponsive
hypocalcaemia.
Herd surveillance for animals at risk in
herds using anionic salts as preventative
measure
When strategies to prevent milk fever are in
place, an ongoing surveillance plan should be
implemented to monitor the success of the
prevention strategies, and to attempt to identify
individual animals at risk, in order to make sure
that extra measures are taken in these animals to
prevent the disease.
Firstly one could use Epidemiological knowledge
and identify multiparous, high producing cows
and cows that have suffered with milk fever in
previous lactations as animals at riks.
Secondly, and currently the most common
method used, is to test urine pH in dry cows to
indirectly supply evidence of osteoclastic activity.
Urine pH should ideally be in the range 6 to 6.8. It
is however common to find individual cows with
higher urine pH, and these cows are at risk of
developing milk fever.
A minimum of 3 days on the anionic salt ration
is recommended before urine pH is monitored.
The veterinarian must therefore verify the
duration on the ration before including cows in a
surveillance sample.