Ionophore And Water Deprivation Flashcards
What are the uses of ionophores?
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
What are the properties of ionophores?
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
How are animals usually exposed to ionophores?
Eating feeds that contain more than the recommended levels/added accidentally
Malicious poisoning
What speices are most sensitive to ionophore toxicity?
Equine
Concurrent administration of what drugs, increases ionophore toxicosis?
Cardiac glycosides Tiamulin Chloramphenicol Erythromycin Sulfonamides
T/F: ruminants only absorb about 50% of monensin but monogastrics absorb almost all
True
How is monensin metabolized? Where is it excreted?
P450 enzyme in liver
(Slowest metabolism in horse because they are deficient in oxidative demethylases)
Excreted in bile
What is the MOA of monensin?
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
Horse
Anorexia, profuse sweating, colic, depression, incoordiation, hyperventilation, tachycardia, tachyarrythmias, prostration, and death
Dx?
Monensin toxicosis
Cattle
Anorexia, diarrhea, depression, labored breathing, ataxia, prostration, and death
Dx?
Monensin toxicity
Signs of monensin toxicity in dog?
Ataxia, muscle weakness of hindlimbs, respiratory paralysis, dysuria, constipation, and depression
What lesions are seen in monensin toxicity?
Cardiac and skeletal muscle lesions - pale with white streaks
What is the best sample for detection of ionophore toxicity?
Feed
Others - GI contents, liver, and feces
What changes would you see in lab diagnostics for ionophore toxicity?
Elevated enzymes of muscle origins
- creatine kinase
- aspartame transaminase
Elevated
- lactic dehydrogenase
- alkaline phosphatase
Increased PCV
Decreased serum Ca and K
What is the DDX for ionophore toxicity in horses ?
Colic
Blister beetle ingestion (cantharidin )
Axoturia
What is the DDx for ionophore toxicity in cattle?
Vit E/selenium toxicity
Poisonous plants
What is the DDX for ionophore toxicity in poultry/
Nutritional Coffee senna Botulism Na /water dep Mycotoxins Round-heart dz Downer syndrome
What is the treatment for ionophore toxicity?
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
What is the source of water dep/ Na toxicosis?
Ingestion of salt licks or ice-melts
Drinking water may contain salt
What factors can cause excess sodium and water deprivation?
Overcrowding
Frozen water
Unpalatable (medicated) water
Lack of water
What effect does salt have on mucous membranes?
Mild irritant
What is the acute oral leather does of salt in horse, cattle, and swine?
2.2g/kg
What species are most susceptible to water dep toxicosis?
Pig, cattle, and poultry
How is sodium distributed over the body?
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
What is the MOA of of water dep/ Na toxicosis?
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
What are clinical signs of water deprivation?
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
What lesion in pathoneumonic in pigs for water dep toxicosis?
Eosinophilic meningioencephalitis (filling of cerebral and meningial perivascular spaces with eosinophils)
What samples do you take for lab analysis of water dep?
Serum and CSF
Brain sodium concentrations above 2000ppm support diagnosis
Salt in feed
What is the DDX for water deprivation?
Encephalitic dz
-trauma, tumor, heat stroke, viral encephalomyelitic conditions
Chlorinated hydrocarbons insecticides
Roxarsone
Pseudorabies
What is the prognosis of water deprivation?
Poor
Mortality is about 50%
What is the treatment of water dep toxicosis?
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
