Detomidine 10 mg/mL / Xylazine 50 mg/mL Dosages & Usages
Horse owners, managers and veterinarians are frequently faced with a need to to calm excitable horses or to provide relief from minor pain, or to facilitate minor or minimally-invasive procedures such as bronchoscopy, bronchoalveolar lavage, nasogastric intubation, rectal palpations and suturing skin lacerations.
In such cases, general sedation is usually not necessary, and in many cases, could introduce undesirable risk factors. Here, the need arises for gentler sedation that can replace physical restraint and improve safety during treatments, diagnostics and transport. Such medicines and formulations are ideal for nervous horses or where there is a need for added control during clipping, shoeing, dental treatments, etc.
Detomidine is used primarily as a sedative, anesthetic adjunct, and analgesia, and it is used in horses more often than in other species. When used to treat pain from colic in horses, the duration of effect can be up to several hours. Detomidine also has been administered for epidural analgesia.1
Detomidine hydrochloride is an imidazole derivative and α₂-adrenergic agonist, and is widely used as a large animal sedative. Detomidine is used to calm excitable horses and to provide pain relief, facilitating procedures such as bronchoscopy, bronchoalveolar lavage, nasogastric intubation and suturing skin lacerations. It is also approved for use as a local infiltration anesthetic for castration.
Detomidine is well absorbed after oral administration, but due to a high first-pass effect, little is available systemically. The drug is apparently rapidly distributed into tissues, including the brain after parenteral administration. It is extensively metabolized, then excreted primarily into the urine. Peak sedative actions can range from 5-20 minutes post IM injection in horses.2
Equine Dosages: Injection: 20 – 40 micrograms/kg (0.02 – 0.04 mg/kg) IV or IM (IV only for analgesia). Effects generally occur within 2-5 minutes. Lower dose will generally provide 30-90 minutes of sedation and 30-45 minutes of analgesia. The higher dose will generally provide 90-120 minutes of sedation and 45-75 minutes of analgesia. Allow animal to rest quietly prior to and after injection.2
Xylazine is an alpha-2 adrenergic agonist used for its sedative & analgesic in a variety of species. It is also used as an emetic in cats. It also possesses muscle relaxant properties. Although xylazine possesses several of the same pharmacologic actions as morphine, it does not cause CNS excitation in cats, horses or cattle, but causes sedation and CNS depression. In horses, the visceral analgesia produced has been demonstrated to be superior to that produced by meperidine, butorphanol, or pentazocine.2
In horses, signs of sedation include a lowering of the head with relaxed facial muscles and drooping of the lower lip. The retractor muscle is relaxed in male horses, but unlike acepromazine, no reports of permanent penile paralysis have been reported. Although, the animal may appear to be thoroughly sedated, auditory stimuli may provoke arousal with kicking and avoidance responses.
a) Standing sedation and analgesia: Full dose is 1 mg/kg IV; for intraoperative use IV dose is usually lower than the full dose or a CRI can be used. CRI dosages reported range from 2.1 – 4.2 mg/kg/h. Epidural dosages range from 0.17 – 0.25 mg/kg.8 Alternately, 0.5 – 1.1 mg/kg IV (onset of peak action in 2-5 minutes; duration ≈30 minutes); 1 – 2 mg/kg IM (onset of peak action in 15 minutes; duration ≈30 minutes). For prolonged procedures: 0.5 mg/kg IV followed by a CRI of 0.65 mg/kg/h.20
b) Field anesthesia: (extra-label): Sedate with xylazine 1 mg/kg IV; 2 mg/kg IM given 5-10 minutes (longer for IM route) before induction of anesthesia with ketamine 2 mg/kg IV. Horse must be adequately sedated (head to the knees) before giving the ketamine (ketamine can cause muscle rigidity and seizures).2
Warnings and Contraindications
Detomidine is contraindicated in horses with pre-existing AV block and sinoatrial (SA) node dysfunction, severe coronary insufficiency, cerebrovascular disease, respiratory disease, or chronic kidney disease. It should be used with caution in horses with endotoxic or traumatic shock or approaching shock, advanced hepatic or renal disease; stress due to temperature extremes, fatigue, or high altitude; patients treated for intestinal impactions; horses with suspected colic, as it may mask abdominal pain or changes in respiratory & cardiac rates.
Xylazine is contraindicated in animals receiving epinephrine or having active ventricular arrhythmias. It should be used with extreme caution in animals with preexisting cardiac dysfunction, hypotension or shock, respiratory dysfunction, severe hepatic or renal insufficiency, preexisting seizure disorders, or if severely debilitated. Because it may induce premature parturition, it should generally not be used in the last trimester of pregnancy.2
For pain in general, detomidine appears to be more potent and longer acting than xylazine alone. In combination with xylazine, detomidine is reported to provide superior relaxation and recovery times.
1Papich, M., DVM. Detomidine Hydrochloride. Saunders Handbook of Veterinary Drugs (Fourth Edition), 2016.
2Plumb's Veterinary Drugs.
About NexGen Pharmaceuticals
NexGen Pharmaceuticals is an industry-leading veterinary compounding pharmacy, offering sterile and non-sterile compounding services nationwide. Unlike other veterinary compounding pharmacies, NexGen focuses on drugs that are difficult to find or are no longer available due to manufacturer discontinuance or have yet to be offered commercially for veterinary applications, but which still serve a critical need for our customers. We also specialize in wildlife pharmaceuticals, including sedatives and their antagonists, offering many unique options to serve a wide array of zoo animal and wildlife immobilization and anesthesia requirements.
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The information contained in this blog post is general in nature and is intended for use as an informational aid. It does not cover all possible uses, actions, precautions, side effects, or interactions of the medications shown, nor is the information intended as medical advice or diagnosis for individual health problems or for making an evaluation as to the risks and benefits of using a particular medication. You should consult your veterinarian about diagnosis and treatment of any health problems. Information and statements have not been evaluated by the Food and Drug Administration ("FDA"), nor has the FDA approved the medications to diagnose, cure or prevent disease. Medications compounded by NexGen Pharmaceuticals are prepared at the direction of a veterinarian. NexGen Pharmaceuticals compounded veterinary preparations are not intended for use in food and food-producing animals.
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