sedation of large animals.docx

**SEDATION OF LARGE ANIMALS** - Alpha-2 adrenergic agents, benzodiazepines, and phenothiazines are used as preanesthetic medications and sedatives in farm animals. - Common drugs include: - Xylazine - Acepromazine - Diazepam - Pentobarbital - Butorphanol...

**SEDATION OF LARGE ANIMALS** - Alpha-2 adrenergic agents, benzodiazepines, and phenothiazines are used as preanesthetic medications and sedatives in farm animals. - Common drugs include: - Xylazine - Acepromazine - Diazepam - Pentobarbital - Butorphanol - Chloral hydrate **Alpha-2 Adrenergic Agents** - **Xylazine**, **detomidine**, and **romifidine** act on the central nervous system's alpha-2 adrenoreceptors, causing sedation, analgesia, and muscle relaxation. - Higher doses of **xylazine** and **detomidine** induce recumbency and profound CNS and respiratory depression. - The drug amount required for sedation depends on an animal\'s temperament and excitement at the time of administration. - Excited animals cannot be sedated with standard dosages. **Dosage Information** - **Cattle** - Intravenous or intramuscular doses of **xylazine** (0.015 to 0.025 mg/kg) sedate cattle without inducing recumbency. - Higher doses (0.1 to 0.2 mg/kg) induce recumbency and light anesthesia. - Sedation is a common side effect after epidural administration of xylazine. - **Sheep and Goats** - These animals are more sensitive than cattle to **xylazine\'s** sedative effects. - It can cause pulmonary resistance and sometimes fatal pulmonary edema in sheep. - Avoid using **xylazine** in sheep if possible. - A low concentration of **xylazine** (20 mg/mL vs. 100 mg/mL) is recommended to avoid overdosage. **Side Effects of Xylazine** - Respiratory depression - Hypotension - Bradycardia (cardiopulmonary depression) - Hyperglycemia - Hypoinsulinemia - Increased urine production - Can induce vomiting, especially at high doses **Special Considerations** - Reports suggest **xylazine** may have an oxytocin-like effect in near-term pregnant cows, so use with care during pregnancy (may cause abortion). - **Detomidine** has less of an oxytocin-like effect than xylazine. - **Horses** - **Xylazine** causes horses to shift weight to their front legs and numbs neurons, making them prone to kicking during rear-end procedures. - **Xylazine** alone should not be used as a sedative for rear-end procedures; it may be combined with **butorphanol** for sedation. - **Swine** - **Xylazine** (0.5 to 3 mg/kg IM) can be used alone for sedation but is usually combined with other drugs such as: - **Ketamine** (2-5 mg/kg IV or 5-10 mg/kg IM) - **Telazol** (1-3 mg/kg IV or 2-5 mg/kg IM) **Reversing Xylazine Effects** - **Xylazine** sedation, analgesia, cardiopulmonary depression, and muscle relaxation are reversible. - **Tolazoline** and **yohimbine** are commonly used to reverse these effects. - **Yohimbine** - Recommended dose: 0.12 mg/kg IV in cattle, higher doses for small ruminants (up to 1 mg/kg IV). - **Tolazoline** - Recommended dose: 0.5 to 2.0 mg/kg IV for ruminants. - Fewer adverse effects occur with tolazoline compared to yohimbine. **Phenothiazine** - **Acepromazine** is a tranquilizer commonly used in horses but is infrequently used in cattle due to its long duration of action and withdrawal times. - Typically administered parenterally (**IV, SQ, or IM**). - It provides calming and muscle relaxation but no analgesia. - **Dosages**: - Cattle: **0.03 to 0.05 mg/kg IV**. - Sheep and Goats: **0.05 to 0.1 mg/kg IV**. - Horse: *unspecified*. - **Considerations**: - **Acepromazine** may increase the risk of phimosis in breeding males. - It predisposes adult cattle to **regurgitation** during anesthesia. - **Swine**: - **Acepromazine** helps reduce the risk of **hyperthermia** and **porcine stress syndrome**. - The dose for tranquilizing swine is **0.5 mg/kg IM**. **Benzodiazepines** - **Diazepam** can be used to provide brief sedation in small ruminants. - Dose: **0.25 to 0.5 mg/kg IV**. **Barbiturates** - Low doses of **pentobarbital** (**2 mg/kg IV**) can be used in cattle to produce sedation. - Large doses should be avoided due to the risk of **ataxia** and **delirium**. - Sedation is moderate and lasts **30 to 60 minutes**.