H2O Deprivation

Question 1

Sources of H2O deprivation

Answer 1

Feeding brine, whey, garbage
-Ingestion of Na+ licks or ice-melts
-Drinking H2O may contain Na+
-All factors that cause ↑Na+ & H2O ↓
(Overcrowding, frozen H2O
Unpalatable (medicated) H2O, lack of)

Question 2

Physical and chemcial properites of h2o deprivation

Answer 2

• Tasty

- Mild irritant effect on MM

Question 3

toxicokinetics of h2o deprivation

Answer 3

Na+ rapidly absorbed from GIT & WD
-Enters brain by passive diffusion & is removed by active
transport
-The excess of absorbed Na+ following large dietary intake is rapidly
excreted in U+ as long as there is enough H2O
-HrTonicity of the
B+ and toxicosis

Question 4

toxicity of h2o deprivation

Answer 4

NaCl normally present @ ~ than 10% salt in feed w/access to H2O
-Pc, Bv & Av > susceptible K9s

Question 5

MOA of h2o toxicosis

Answer 5

Normal plasma Na+ levels: 135-145mEq/L & in CSF: 130-140 mEq/L

• ↓H2O intake & dehydration ↑plasma Na+ to 150-190 mEq/L & CSF to 145-185 mEq/L
• Hi Na+ in the brain inhibits anaerobic glycolysis  lack of E needed for active transport
• Na+ trapped in the brain attracts H2O b/c of the osmotic gradient, cerebral edema

Question 6

CS/Lesions of h2o deprivation

Answer 6

Early constipation & thirst, V+, PU & met acid
-Intermittent convulsive S+
•0.5 to 2-3 m, Interrupted by other signs
•Not elicitable
-Circling, pivoting, head-pressing, blindness, deafness, inability to eat, drink or recognize feed or H2O
-Av only show depression, ascites & collapse
•Lesions:
-GI congestion/inflammation w/ pinpoint ulcers
-Fluid in body cavities & organ edema
-Prominent cerebral edema
Histopathologically, eosin meningoencephalitis (filling of cerebral & meningeal perivascular spaces w/eosinos) is pathognomonic in Pc only if the animal dies early

Question 7

Lab dx and ddx of h2o toxicosis

Answer 7

Lab Dx:
-Serum & CSF/ocular fluid [Na+]≥160mEq/L
-Brain [Na+] > 2000 ppm support dx
-Na+ in feed
-Hx, encephalitic signs, lesions & lab dx
•DDx
-Encephalitic diseases
•Trauma, Tumor, Heat stroke, viral encephalomyelitic conditions
-CCH
-Pseudorabies

Question 8

Tx/Px of H2O toxicosis

Answer 8

Giving small amts of H2O (0.5% of body weight) gradually over 2-3d, if the animal is able to drink (recovery is 50%)
-Giving H2O in large amts may kill the animal by aggravating cerebral edema
-Intravenous fluids (5% dextrose) & furosemide in SA
-Anticonvulsants in SA
•Prognosis - Poor
-Mortality ~ 50%