VPT 421: Veterinary Toxicology (2+0)

PHENOTHIAZINE

• Phenothiazine is very insoluble in water and although stable when dry, is readily oxidized when wet.
• Due to the insolubility of phenothiazine in water, it is formulated in suspensions and if not shaken well prior to dosing, the drug will be unevenly distributed to the animals.
• The toxicity of phenothiazine has limited its use in swine and altogether prevented its use in the dogs, cats and human beings.
• It is used in ruminants, horses and fowl.
• The problem in small animals is reportedly severe CNS depression.
• Deaths among sheep from phenothiazine toxicosis are rare. However, debilitated, anemic cattle are even more susceptible than similarly debilitated sheep.
• An important toxic effect of phenothiazine in animals in poor condition is hemolysis which compounds an existing anemia in some such animals resulting in death.
• Phenothiazine toxicosis and death has occurred more in horses than in other domestic animals.
• Most toxicoses have occurred in debilitated and anemic horses.