Term
| know that a horse’s halter should not be left on during a surgical or anesthetic procedure |
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Definition
| - superficial nerves (ex facial nerve, radial nerve) can become damaged (neuropathy) if intraoperative padding is inadequate or the halter is inadvertently left on during anes |
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Term
| Equine patients weighing more than how many Kg are usually placed on a large animal anesthesia machine. |
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Definition
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Term
. Know the specific drugs that would be the most likely to be used to produce standing chemical restraint in horses.
Xylazine + butorphanol IV |
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Definition
Xylazine + butorphanol IV
- Xylazine 0.5 – 1.1 mg/kg + butorphanol 0.05 – 0.1 mg/kg
- Provides 20 to 30 min of chemical restraint
- Extend sedation with xylazine 0.025 – 0.5 mg/kg + butorphanol 0.025 – 0.05 mg/kg as needed |
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Term
. Know the specific drugs that would be the most likely to be used to produce standing chemical restraint in horses.
Detomidine + morphine IV |
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Definition
Detomidine + morphine IV
- Detomidine 0.02 mg/kg IV + morphine 0.1 mg/kg
- provides ~ 60 min of sedation
- administer detomidine 0.01 mg/kg to extend sedation
- morphine has a longer duration of action than detomidine and does not need to be readministered |
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Term
| What two superficial nerves are the most susceptible to pressure neuropathies in horses? |
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Definition
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Term
| . Know what causes myopathy in horses that have undergone anesthetic procedures and what can be done to prevent myopathy in those patients. |
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Definition
- myopathy (caused by a lack of muscle blood flow, manifests in recovery as muscle hardness, pain and weakness (commonly referred to as “tying up”)
- may be caused by inappropriate or insufficient padding |
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Term
| . What is the main reason for including guaifenesin in an induction protocol in horses? |
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Definition
| - used as a muscle relaxant before the induction bolus is given. Guaifenesin is given to effect via a pressure bag until the horse is sufficiently relaxed to under go induction |
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Term
| . Inhalant anesthetic induction via nasotracheal tube placement is most appropriate for which equine patients? |
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Definition
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Term
| What are the most appropriate sizes of IV catheters to use in horses? |
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Definition
| 4 – 6 inch, 14 – 16 gauge |
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Term
| What are the two most common inhalant anesthetics used to provide maintenance of anesthesia in adult horses? |
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Definition
Isoflurane
- (Foals only) Induction 4 – 5% by nasotracheal tube
(lower in sick foals)
- maint 1.5 – 2.5%
Sevoflurane
- (Foals only) Induction 5 – 8% by nasotracheal tube (lower in sick foals)
- maint 2.5 – 4% |
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Term
| . What is the weight of the average adult horse? |
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Definition
| 350 – 500 kg, some larger breeds may weigh as much as 1000 kg |
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Term
| What drugs cannot be used in horses due to colic potential? |
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Definition
| Anticholinergic drugs reduce GI motility, which may result in colic. This class of drugs is reserved for arrhythmia tx and for CPR |
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Term
| . After induction with the most commonly used IV induction agents, the usual maximum period that an equine patient will remain anesthetized without further administration of additional agents is about how many minutes? |
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Definition
| Usually no more than 10 – 20 min |
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Term
| of all the phases of anesthesia, ___________ poses the highest risk to the horse, and as is the phase over which the anesthetist has the least control. |
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Definition
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Term
| What is one way maint in horses differs from small animal anes? |
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Definition
| Sudden unexpected movement can occur w/o any change in depth |
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Term
| . What are the most common complications during the maintenance of anesthesia in adult horses with inhalant anesthetics? |
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Definition
hypotension
- mean arterial BP < 70 mm Hg
- has been shown to contribute to myopathy so tx w/ drugs is frequently indicated if increased fluid rate, decreased fluid rate, and surgical stimulation do not increase BP.
- The most common drug to support BP is the positive inotrope dobutamine (commonly admin via a syringe pump).
- dobutamine (and other positive inotropes) may cause arrythmias so the ECG must be closely monitored during dobutamine infusion
Hypoventilation
- so common in anes horses (esp dorsal recum) that a ventilator is often used to maintain normal ventilation
hypoxemia
- usually defined as PaO2 <80 mm Hg
- can occur in any horse
- more common in horses that are obese, preg, have torsed intestines, or are placed in dorsal recumbency
- several possible causes, incl hypoventilation, ventilation-perfusion mismatch, lung dz, and low cardiac output |
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Term
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Definition
- mean arterial BP < 70 mm Hg
- has been shown to contribute to myopathy so tx w/ drugs is frequently indicated if increased fluid rate, decreased fluid rate, and surgical stimulation do not increase BP.
- The most common drug to support BP is the positive inotrope dobutamine (commonly admin via a syringe pump).
- dobutamine (and other positive inotropes) may cause arrythmias so the ECG must be closely monitored during dobutamine infusion |
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Term
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Definition
| so common in anes horses (esp dorsal recum) that a ventilator is often used to maintain normal ventilation |
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Term
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Definition
usually defined as PaO2 <80 mm Hg
- can occur in any horse
- more common in horses that are obese, preg, have torsed intestines, or are placed in dorsal recumbency
- several possible causes, incl hypoventilation, ventilation-perfusion mismatch, lung dz, and low cardiac output |
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Term
| . Know the common pharmaceuticals that are used to treat hypotension in an anesthetized horse. |
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Definition
- The most common drug to support BP is the positive inotrope dobutamine (commonly admin via a syringe pump).
- dobutamine (and other positive inotropes) may cause arrythmias so the ECG must be closely monitored during dobutamine infusion |
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Term
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Definition
- Induction drugs given as rapid bolus inj, rather than “to effect”
- Most commonly by IV injectable agents, typically ketamine alone or in combo w/ other agents (ketamine and diazepam or midazolam
- Exception is when using muscle relaxant guaifenesin, which is administered IV rapidly IV to effect by placing it in a pressure bag. Once the horse should signs of ataxia (typically knuckling of the forelimbs at the carpi and/or fetlock, the induction agent (ketamine) is given as a bolus
- If too light to intubate or hoist, can give a bolus dose of ketamine at 0.4 mg/kg (1/5 of induction dose) or thiopental 0.5 mg/kg IV |
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Term
| . Know the steps and process for the preanesthetic preparation of horses. |
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Definition
Preanesthetic/Catheterization
- tranq/alpha2-agonists/and opiods commonly used as preanes, given via IM or IVroute
- pt assessment
- IV catheter (4 – 6 “, 14 – 16 g) almost always in one of the jugular veins, sm dose local anes over cath site
- Some must be sedated first (by giving premeds at this time)
- Alternate: low dose xylazine
- After catheterization, flush any feed material out of mouth with lg syringe to prevent aspiration during induction/recovery
- Clean feet before sedation, remove shoes or wrap hooves |
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Term
| . Know the proper processes and steps for endotracheal intubation in horses. |
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Definition
Equipment needed
- ET tubes (2 diff sizes) (Adult horses typically 22, 26, or 30 m, foals smaller but rarely less than 10 mm)
- Longer tubes of smaller diameter may be needed for successful nasotracheal intubation in foals
- Mouth gag
- 60 ml syringe for cuff
- gauze sponge to grasp the tongue
- tube must be checked
- may be lubed with sm amt sterile water-soluble lube but not needed in most horses
Intubation
- performed blindly by feel, uncommon for it to pass into the esophagus
- head extended, tongue gently pulled to side, mouth gag or speculum placed
- ET tube passed through the gag, over base of tongue, into larynx
- If resistance met at level of laryngopharynx, withdraw the tube 1 – 2 inches, rotate it 90 degrees, and advance it again
- Advancement w/o resistance indicates success
- Confirmed by feeling air move when the horse exhales or when pushing on thoracic wall
- ET tube either tied to the speculum or taped to muzzle
- If tube won’t pass into larynx, slightly changing angle of head or tube or trying smaller tube usually works
- If any resistance – don’t force tube!
- Often cuff partially inflated before hoisting, then once pt connected to machine, cuff is checked for proper inflation as with sm animal
Nasotracheal intubation
- may be preferred over orotracheal intubation in horses undergoing some sx/tx of head/neck
- performed by passing a well-lubed tube, one size smlr than likely orotracheal tube size, into the ventral nasal meatus w/ the head in the same position as for endotracheal intubation
- tube should be passed very gently in order to avoid damaging the nasal mucosa and turbinates and causing epistaxis |
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Term
| Which devices could (or should) be used to monitor the physiological status of anesthetized horses? |
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Definition
| arterial catheter placed in a peripheral artery (facial, transverse facial, dorsal pedal) to monitor BP and arterial blood gas values taken every 30 – 60 min |
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Term
| What is in “Triple Drip”? |
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Definition
maint of anes in the field and for procedures of less than 1 hr in duration is typically accomplished using TIVA. TIVA is generally characterized by higher BP, less resp depression, and more active palpebral reflexes than inhalant anes.
The most common drug combo for TIVA is “triple drip”, a co-infusion of guaifenesin, ketamine, and xylazine |
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Term
| How to prepare and administer Triple Drip |
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Definition
- add 2.5 ml of xylazine (100 mg/ml) to 500 ml of 5% guaifenesin
- add 5 ml of ketamine (100 mg/ml) to 500 ml of 5% guaifenesin
- each ml of “triple drip” contains 0.5 mg xylazine, 1 mg ketamine, and 50 mg guaifenesin
- admin via CRI at 1.5 ml/kg/hr
- this equates to xylazine 0.75 mg/kg/hr, ketamine 1.5 mg/kg/hr, and guaifenesin 75 mg/kg/hr
- temp increase infusion rate if pts anes depth becomes light |
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Term
| Know the steps that can be taken to help insure that horses maintain an adequate blood pressure during surgical or anesthetic procedures. |
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Definition
- increase IV fluid rate
- decrease anesthetic depth
- surg stimulation
- dobutamine |
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Term
| . When monitoring the stage and plane during equine anesthesia and recovery, which reflex(es) would be the most indicative of the depth of the surgical plane, or the degree of recovery. |
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Definition
Signs of recovery:
- as recovers, will progress back through the stages and planes of anesthesia
- many develop nystagmus
- rapid nystagmus accompanied by paddling generally means that a horse will get up too soon and have a rough recovery
- in this event, may sedate the horse with 0.1 – 0.2 mg of xylazine per kg IV
- other signs, chewing, swallowing, and purposeful ear, limb and tail movements |
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Term
| . Know the benefits of using preanesthetic agents in equine patients and what those agents could be. |
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Definition
| - tranq/alpha2-agonists/and opiods commonly used as preanes, given via IM or IVroute |
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Term
| Know the physical signs and stages that would be seen in an equine patient recovering from an anesthetic procedure |
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Definition
- as recovers, will progress back through the stages and planes of anesthesia
- many develop nystagmus
- rapid nystagmus accompanied by paddling generally means that a horse will get up too soon and have a rough recovery
- in this event, may sedate the horse with 0.1 – 0.2 mg of xylazine per kg IV
- other signs, chewing, swallowing, and purposeful ear, limb and tail movements |
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Term
| What are the most important considerations the veterinary technician needs to pay attention to when assisting with laser surgery? |
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Definition
Eye hazards
- everyone must wear eye protection specific for that particular laser light. Serious corneal or retinal damage
- protect pt eyes also
- when a CO2 laser is used, moistened sponges can be placed over the eyes for protection because the CO2 laser beam is absorbed by water. Pt eye shields are also available.
Skin hazards
- may occur from direct or scattered laser beams
- may be in best interest to wear gloves and a gown for added protection
Fire hazards
- poss fire hazards incl the sx drapes, anesthetic agents, oxygen, animal’s fur, alcohol products used in sx prep, methane from flatulence
- w/ CO2 laser, wet sponges can be placed around the sx area for protection of drapes
Smoke plume hazards
- smoke plume emitted from laser contact w/ tissue contains toxic and carcinogenic chemicals as well as bacteria and viral particles
- an evacuator is usually purchased with laser machines
- should never be performed w/o an evacuation system w/in 1 – 2 in of smoke’s origin
- reg sx room masks may not filter all toxic or infectious particles
Other concerns
- always make sure the cuff of the ET tube is inflated properly to decrease the chance that gaseous vapor or oxygen will escape
- standard PVC tubes may be at risk for damage and ignition
- laser-safe ET tubes can be purchased for oral cavity procedures or can lay wet sponges around standard ET tube when CO2 lasers are used |
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Term
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Definition
- minimally invasive abdo procedure performed for the purpose of examining the peritoneal cavity and its viscera
Equipment:
- laparoscope or telescope
- trocar-cannula units
- fiberoptic light cable
- light source
- Veress insufflation needle
- gas insufflator (CO2, nitrous oxide or room air – CO2 recc – high rate of absorption. . Abdo pressures should not exceed 15 mm Hg
- camera/video system
- gen use soft tissue pack
> scalpel handles
> Blades
> mosquito forceps
> drapes – four quarter draping method should be considered, single fenestrated drapes are specifically not appropriate for this procedure
Misc:
- pt fasted for 12 hrs to prevent regurg and to keep the stomach from being distended (increased risk of traumatic puncture abd difficulty in visualization of target organs)
- bladder expressed prior
- clipped xiphoid process to pubis, wide laterally for placement of accessory ports |
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Term
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Definition
- The technique of examining internal body structures using specialized optical instruments
- Generally considered a high-yield and noninvasinve or minimally invasive procedure (usually no or small incision)
- High yield in that it often results in dx and therapeutic benefits for the pt
- Allows dr to examine tissues directly, obtain bx samples, and perform therapeutic procedures, such as the removal of FB |
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Term
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Definition
| the endoscopic technique of examining the stomach, indicated for the eval of animals w/ signs of gastric dz |
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Term
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Definition
– the endoscopic technique of examining the esophagus
Dx and tx of esophageal dz, indicated for the eval of animals w/ sign sof esophageal dx |
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Term
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Definition
| Duodenoscopy – – the endoscopic technique of examining the duodenum, aids in the dx and tx of sm intestinal dz |
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Term
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Definition
| – examines the rectum, lg intestine, and cecum, aids in the dx and tx of lg bowel dx |
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Term
| 31. Which minimally invasive instrument would a veterinarian most likely use to check the urinary bladder of a patient? |
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Definition
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