Dehydration

Etiology, types, diagnosis, assessment and treatment of dehydration by Prof Mohamed Ghanem

1. By
Prof Mohamed Ghanem

2. Definition
A disturbance in water balance in which
more fluid is lost from the body than is
absorbed resulting in reduction in the
circulating blood volume.
In contrast, the rapid ingestion of large
quantity of water can lead to overhydration
(water intoxication)

3. Etiology and pathogenesis
There are 2 main causes for dehydration
1- inadequate water intake
2- excessive fluid loss
inadequate
water intake
Excessive
fluid loss

5. Types of dehydration
1- hypotonic (hyponatremic) dehydration
Occurs in acute diarrhea in calves due to excessive
loss of sodium in feces from extracellular tissues…..
Severe dehydration
2- isotonic (isonatremic) dehydration
Occurs when there is a parallel loss of sodium and
water in case of simple enteritis, copious sweating
and nephrosis….. Mild dehydration
 3-hypertonic (hypernatremic) dehydration
Loss or deprivation of water with minor loss of sodium
Occurs in animals unable to drink due to esophageal
obstruction ….. Mild dehydration

6. Clinical findings
Dryness and shrinkage or wrinkling of skin
Recession of the eye into the orbit is one of the
best indicator of dehydration in calves.
Hypothermia
Loss of body weight
Muscular weakness
Anorexia or inappetance
Excessive animal thirst
Reduction of milk yield in lactating animals
oliguria

7. Field tests to diagnose dehydration
1- pinching test or skin fold test
Pinching the skin of neck and lateral thorax
between fingers rotating 90 degree and note
the time required for the fold to disappear
Normal time: less than 2 seconds, if increases
indicated dehydration.
2- capillary refill time (2 seconds)
3- degree of eye recession in the orbit

8. Sunken eye in a calf with
dehydration

9. Delayed skin fold test in a calf
with dehydration

10. Lab exam
1- increased PCV %
2- increased total proteins
3- metabolic acidosis
4- Elevated level of blood urea nitrogen

11. Treatment
Fluid and electrolyte thrapy
Isotonic saline (0.9% NaCl) to expand blood
volume
5% sodium bicarb in severe acidosis
Lactated ringers in metabolic acidosis
Hypertonic Nacl 7.2% in endotoxic shock

12. Amount of fluids

13. a simple calculation can be done to
identify how much fluid is required.
Take the % dehydrated and multiply by the
calf’s body weight in kg.
For example, (36 kg) calf is determined to
be 9% dehydrated.
.09 X 36 kg = 3.24 – This means that 3.24
liters of fluid (oral electrolytes, or IV fluid)
are required to replace what has been lost.

14. After the initial calculated fluid dose is
administered, additional fluids can be
given at a rate of 5 mL for every 1 kg,
every hour

15. Oral Fluid Administration: Oral fluids
should only be used in calves that are 1-
5% dehydrated

16. Questions
[email protected]
Reference
Veterinary medicine 11
th
ed
Constable et al