Even with nonhuman primate patients whose disease status is known, personal protective equipment including respiratory protection (face mask, N95 respirator, or powered air-purifying respirator [PAPR]), eye protection, and gloves should be worn during examination, especially for triage or when signs of infectious disease might be present.
An appropriately sized restraint cage with a squeeze mechanism should be available for both observation of gait and assessment of neurological status in nonhuman primates in a hospital setting, as well as for safe injection of parenteral sedatives, if they are required.
The basic emergency triage procedures for nonhuman primates are identical to triage procedures for other small mammals. Basic triage examination consists of a survey of the respiratory, cardiovascular, urinary, and neurological systems to identify life-threatening abnormalities.
Blood sampling, IV catheterization, and ultrasonography for focused assessment with sonography for trauma (FAST) scans might be required during triage of nonhuman primates. Sedation might be needed to safely perform diagnostic tests and treatments.
Pain evaluation should always be part of the emergency assessment of nonhuman primates. Inadequate pain control can cause increased stress on the cardiovascular and respiratory systems and can affect recovery from sedation or surgical procedures. Multimodal analgesia is often indicated and might generally increase compliance with oral medications.
Suggested analgesic and opioid drug doses for nonhuman primates include the following:
Buprenorphine in great apes and Old World monkeys: 0.01–0.03 mg/kg, IM or IV, every 6–12 hours as needed
Buprenorphine in New World primates: 0.005–0.01 mg/kg, IM or SC, every 6–8 hours as needed
Extended-release buprenorphine: 0.2–0.25 mg/kg, SC, every 2–5 days as needed
Ibuprofen: 7 mg/kg, PO, every 12 hours as needed
The saphenous and cephalic veins are ideal sites for IV catheter placement in most nonhuman primates. The femoral vein or median cubital vein can also be used for short durations. Catheter size can range from 26-gauge to 18-gauge, depending on the size of the vessel and the patient. In an extreme emergency, a cutdown might allow visualization and quick placement of an IV catheter.
In small primates (< 1 kg), intraosseous placement of catheters might be more achievable. Access is achieved via the femoral greater trochanter or the tibial crest; however, access via the femur is the most straightforward.
Radiography should be used to ensure proper placement of chronic intraosseous catheters. Once placed, catheters should be bandaged to prevent access, even in infants. Because of their strength and dexterity, nonhuman primates often remove catheters by chewing or pulling at them.
Diagnostic imaging should be used when available and appropriate. Radiographic techniques for nonhuman primates are similar to those used for small companion mammals. Ultrasonography is often more sensitive than radiography for identifying abdominal abnormalities.
For chronic conditions such as neoplasia or respiratory problems, CT or MRI might be required to differentiate etiologies. These modalities are also often used prospectively in research settings.
The femoral vein and artery are the preferred sites for blood sample collection in nonhuman primates. If sampling from these sites is tolerated, samples can be collected from awake and restrained patients. Alternative sites for collection of small volumes include the cephalic and saphenous veins.
Pearls & Pitfalls
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Sedation in nonhuman primates can be achieved via parenteral administration of either a dissociative agent such as ketamine alone (5–10 mg/kg, IM, once) or in combination with an alpha-2 agonist like dexmedetomidine (20–30 mcg/kg, IM, once); or a benzodiazepine such as midazolam (0.2–1 mg/kg, IM) or diazepam (1 mg/kg, IM).
Ketamine can decrease the tendency of nonhuman primates to bite during sedation, while still preserving the ability to swallow. However, caution should still be used if accessing the oral cavity during examination. An alternative sedative protocol using tiletamine-zolazepam might provide improved sedation for some species (New World primates: 1–2.5 mg/kg, IM, once; Old World primates: 3–5 mg/kg, IM, once).
Intubation techniques vary because of differences in nonhuman primates' size and anatomy:
Small primates (< 1 kg) and prosimians can be intubated with noncuffed avian endotracheal tubes. Typical sizes are 2 mm and 2.5 mm. If these are unavailable, red rubber tubes can be adapted and used.
Larger primates can be intubated using typical small animal techniques via visualization with a laryngoscope, generally with tubes sized between 3 and 7.5 mm, depending on the primate and life stage.
Because the oral cavity and neck are shorter in a primate than in a dog or cat, it is especially important to measure correct endotracheal tube length and verify placement. Cuffs should not be overinflated or underinflated. Old World primates such as macaques have cheek pouches where food can be stored. Care must be taken to check for and remove any food or debris from these pouches as soon as the patient loses jaw tone, to decrease the chance of aspiration while under anesthesia.
Surgical monitoring of nonhuman primates should include ECG, blood pressure, temperature, pulse oximetry, and capnography. In smaller animals, a Doppler monitor with a human pediatric cuff can be used (easily on the tail) both to measure systolic blood pressure and to monitor auditory heart rates. Physiological norms depend on species and life stage (see the table Normal Vital Parameter Reference Ranges for Nonhuman Primates).
Normal Vital Parameter Reference Ranges for Nonhuman Primates
Species | Rectal Temperature (°C) | Respiratory Rate (Breaths/Minute) | Heart Rate (Beats/Minute) |
|---|---|---|---|
Marmoset | 38.4–39.7 | 30–50 | 240–350 |
Squirrel monkey | 38.0–39.5 | 20–50 | 225–350 |
Capuchin monkey | 36.7–38.5 | 30–50 | 165–225 |
Spider monkey | 36.0–39.0 | 18–35 | 150–210 |
Rhesus macaque | 36.0–39.0 | 10–30 | 150–220 |
Careful consideration should be given to suture type and pattern used in nonhuman primates' skin. Appropriately sized, absorbable, subcuticular or subdermal sutures should be used whenever possible to prevent patient tampering with surgical sites or closures. Although surgical staples or external sutures can be used, with their dexterous fingers and toes, nonhuman primates are much more likely to pull out or remove their own skin sutures/staples than are other veterinary patients.
Nonhuman primate hand dexterity makes placing Elizabethan collars impractical. Bandages might be required to cover and protect suture lines during healing, but nonhuman primates can remove them rapidly upon anesthetic recovery. Applying extra bandage layers or bandaging nonaffected areas of the body (such as the hands) might be necessary to prevent bandage removal; however, this approach should not replace addressing adequate analgesia and mental stimulation during the recovery period.
Key Points
Emergency triage procedures for nonhuman primates are similar to those for other species.
Appropriate personal protective equipment should be worn when handling and examining nonhuman primates.
Nonhuman primates are more likely than other species to pull at skin sutures, making the use of subcuticular or subdermal closure patterns ideal.
In species with cheek pouches, any food or debris should be removed from the pouches immediately after induction of anesthesia to prevent aspiration pneumonia.
