Ionophore And Water Deprivation

Question 1

What are the uses of ionophores?

Answer 1

Anticoccidial in cattle, poultry, and goat
Growth promoter feed additive in cattle

Monensin approved o improve milk efficiency in dairy cattle

Reduction of bloat in rumen acidosis

Question 2

What are the properties of ionophores?

Answer 2

Slightly soluble in water and soluble in organic solvent and oils

Form lipid-soluble complexes with polar cations that are transported across the cell membranes

Question 3

How are animals usually exposed to ionophores?

Answer 3

Eating feeds that contain more than the recommended levels/added accidentally
Malicious poisoning

Question 4

What speices are most sensitive to ionophore toxicity?

Answer 4

Equine

Question 5

Concurrent administration of what drugs, increases ionophore toxicosis?

Answer 5

Cardiac glycosides 
Tiamulin 
Chloramphenicol 
Erythromycin 
Sulfonamides

Question 6

T/F: ruminants only absorb about 50% of monensin but monogastrics absorb almost all

Answer 6

True

Question 7

How is monensin metabolized? Where is it excreted?

Answer 7

P450 enzyme in liver
(Slowest metabolism in horse because they are deficient in oxidative demethylases)

Excreted in bile

Question 8

What is the MOA of monensin?

Answer 8

Disrupt transmembrane electrochemical gradients —> disrupt the mitochondria of highly energetic tissues

Influx of the sodium-ionophore couples increasing intracellular sodium accompanied by increasing intracellular Ca
Sequestering of Ca by mitochondria

Cell death due to disrupted homeostasis

Catecholamines release -> oxidation products and free radicals causing sarcolemmal membrane damage
Disruption of ion concentration in excitable cells

Question 9

Horse
Anorexia, profuse sweating, colic, depression, incoordiation, hyperventilation, tachycardia, tachyarrythmias, prostration, and death

Dx?

Answer 9

Monensin toxicosis

Question 10

Cattle
Anorexia, diarrhea, depression, labored breathing, ataxia, prostration, and death

Dx?

Answer 10

Monensin toxicity

Question 11

Signs of monensin toxicity in dog?

Answer 11

Ataxia, muscle weakness of hindlimbs, respiratory paralysis, dysuria, constipation, and depression

Question 12

What lesions are seen in monensin toxicity?

Answer 12

Cardiac and skeletal muscle lesions - pale with white streaks

Question 13

What is the best sample for detection of ionophore toxicity?

Answer 13

Feed

Others - GI contents, liver, and feces

Question 14

What changes would you see in lab diagnostics for ionophore toxicity?

Answer 14

Elevated enzymes of muscle origins

• creatine kinase
• aspartame transaminase

Elevated

• lactic dehydrogenase
• alkaline phosphatase

Increased PCV
Decreased serum Ca and K

Question 15

What is the DDX for ionophore toxicity in horses ?

Answer 15

Colic
Blister beetle ingestion (cantharidin )
Axoturia

Question 16

What is the DDx for ionophore toxicity in cattle?

Answer 16

Vit E/selenium toxicity

Poisonous plants

Question 17

What is the DDX for ionophore toxicity in poultry/

Answer 17

Nutritional 
Coffee senna 
Botulism 
Na /water dep 
Mycotoxins 
Round-heart dz
Downer syndrome

Question 18

What is the treatment for ionophore toxicity?

Answer 18

No specific antidote

Decrease absorption - activate charcoal, mineral oil, saline cathartics

Symptomatic

• IV fluid and electrolyte therapy
• potassium or hypokalemia
• monitor cardiac function
• horses should not be ridden and stress reduced for several months

VitE to decrease muscle damage

Question 19

What is the source of water dep/ Na toxicosis?

Answer 19

Ingestion of salt licks or ice-melts

Drinking water may contain salt

Question 20

What factors can cause excess sodium and water deprivation?

Answer 20

Overcrowding
Frozen water
Unpalatable (medicated) water
Lack of water

Question 21

What effect does salt have on mucous membranes?

Answer 21

Mild irritant

Question 22

What is the acute oral leather does of salt in horse, cattle, and swine?

Answer 22

2.2g/kg

Question 23

What species are most susceptible to water dep toxicosis?

Answer 23

Pig, cattle, and poultry

Question 24

How is sodium distributed over the body?

Answer 24

Absorbed from GI tract
Enters brain by passive diffusion and is removed by active transport

Excess of absorbed sodium following large dietary intake is rapidly excreted in urine
Excess sodium results in hypertonicity of blood and toxicosis

Question 25

What is the MOA of of water dep/ Na toxicosis?

Answer 25

Normal sodium level in plasma is 135-145mEq/L and are 10mEq/L in cerebrospinal fluid

Restricted water or high sodium increases the osmolality
High sodium in brain —> inhibit anaerobic glycolysis and lack of energy and causes edema by attracting water

Question 26

What are clinical signs of water deprivation?

Answer 26

Vomiting, PU, and metabolic acidosis 
Intermittent convulsive seizures 
Circling, pivoting, and head pressing 
Blindness and deafness
Inability to eat or drink 
Poultry only show depression, ascites, and collapse

Question 27

What lesion in pathoneumonic in pigs for water dep toxicosis?

Answer 27

Eosinophilic meningioencephalitis (filling of cerebral and meningial perivascular spaces with eosinophils)

Question 28

What samples do you take for lab analysis of water dep?

Answer 28

Serum and CSF

Brain sodium concentrations above 2000ppm support diagnosis
Salt in feed

Question 29

What is the DDX for water deprivation?

Answer 29

Encephalitic dz
-trauma, tumor, heat stroke, viral encephalomyelitic conditions

Chlorinated hydrocarbons insecticides
Roxarsone
Pseudorabies

Question 30

What is the prognosis of water deprivation?

Answer 30

Poor

Mortality is about 50%

Question 31

What is the treatment of water dep toxicosis?

Answer 31

Give small amount of fresh water gradually over 2-3days
Giving water in large amounts may kill animal by aggravating cerebral edema
IV fluids and furosemide in small animlas
Anticonvulsant in small animals