Registered veterinary nurses (RVNs) should have a good knowledge of the normal clinical parameters for equine patients. This facilitates the recognition of abnormalities, which can then be recorded and the treatment plan created accordingly.
Clinical parameters in equines
Clinical parameters that should be assessed in equine patients include temperature, pulse and respiration (TPR), digital pulses, mucous membrane colour, capillary refill time and gut sounds (borborygmi). Table 1 displays the normal clinical parameters for horses, donkeys and foals. These readings should be taken twice daily but may be required more frequently in critically ill horses.
| Equid | Temperature (⁰C) | Pulse (beats per min) | Respiration (breaths per min) | Mucous membrane colour | Capillary refill time | Gut sounds | Digital pulses |
|---|---|---|---|---|---|---|---|
| Horse | 37 to 38.5 | 24 to 40 | 8 to 16 | Pale pink | Under 2 secs |  Noise present in all four quadrants |
Nothing abnormal detected |
| Donkey | 36.5 to 37.8 | 36 to 52 | 12 to 38 | Pale pink | Under 2 secs | Noise present in all four quadrants |
Nothing abnormal detected |
| Foal (1 month onwards) |
37.7 to 38.7 | 60 to 80 | 20 to 40 | Pale pink | Under 2 secs | Noise present in all four quadrants |
Nothing abnormal detected |
During a clinical patient examination, a competent handler wearing personal protective equipment (PPE), such as a hard hat, steel-toe-capped boots and gloves, should restrain the patient. The RVN examining the patient should also wear appropriate PPE. Clinical parameters should be taken in a quiet environment, and the patient should be relaxed to get the most accurate readings.
Clinical parameters should be taken in a quiet environment, and the patient should be relaxed to get the most accurate readings
Measuring the respiratory rate of equids
The respiratory rate can be counted by watching the abdomen move with each breath. The number of breaths should be counted over one minute, which can be done from outside the stable to avoid disturbing the horse. Lung sounds should also be assessed. The trachea and both sides of the thorax should be auscultated on inspiration and expiration, listening for abnormal harshness, crackling or wheezing.
Measuring the pulse rate of equids
The most common place to take a pulse rate in equids is the submandibular artery, which is palpated on the medial side of the mandibular ramus, just in front of the muscular section of the ventral cheekbone. Once the artery is located with the fingertips, the pulse rate should be counted for one minute.
A normal pulse should be strong and regular, while a horse with compromised cardiovascular function may have a weak and irregular pulse. The heart and pulse rates should be synchronised, with the pulse strength and rhythm patterns noted.
Measuring digital pulses in equids
In healthy horses, digital pulses should be hard to find. The digital arteries are located and palpated in the distal limb at the level of the proximal sesamoid bones and the caudal aspect of the pastern. The fingertips are used to palpate the pulse and assess its strength.
A strong or “bounding” pulse can be an indication of inflammation in the distal limb. Strong digital pulses are associated with several conditions, such as laminitis and foot abscesses.
Measuring the heart rate of equids
Auscultation of the heart is a crucial component of a clinical examination. In equids, the heart rate should be auscultated just behind the elbow in the axillary region (Figure 1) – moving the forelimb forward can facilitate ideal positioning for the stethoscope. A systematic examination involves listening to both sides of the thorax. The number of beats should be listened to for at least one minute to allow time for any abnormalities to be detected. Once the heart rate is stabilised, the number of beats over 15 seconds can be counted and multiplied by four to give the beats per minute.
Close attention should be paid to murmur sounds or the presence of an arrhythmia.
Abdominal auscultation in equids
Continual noise should be heard in all four quadrants when auscultating the abdomen of equines. Gut sounds or borborygmi are recorded as seen in Table 1. The cross represents the four quadrants of the abdomen, and the + signs indicate how much noise is heard in each quadrant:
- Hyperactive gut sounds are recorded as three pluses
- Normal gut sounds are recorded as two pluses
- Hypoactive gut sounds are recorded as one plus
If gut sounds are absent, no pluses are recorded and a treatment plan must be devised and implemented immediately.
Method
Auscultation of the gastrointestinal tract is performed with a stethoscope across four quadrants:
- Upper left: left paralumbar to midflank
- Lower left: left midflank to the ventral abdomen
- Upper right: right paralumbar to midflank
- Lower right: right midflank to ventral abdomen
The ventral midline area can also be assessed.
Each quadrant should be auscultated for one to two minutes. Time should be spent auscultating the lower left quadrant because this is the area where the pelvic flexure sits and is a common site for impactions. Caecal emptying sounds, or “the caecal flush”, are heard on the right paralumbar fossa. They sound like water flushing down a drainpipe and occur every one to two minutes in the normal horse.
Decreased or complete cessation of gut sounds may suggest serious and detrimental changes to the intestine
Decreased or complete cessation of gut sounds may suggest serious and detrimental changes to the intestine. Hypermobile gassy and fluid gut sounds may indicate spasmodic colic, impending colitis or enteritis.
Measuring mucous membrane colour and capillary refill time in equids
The mucous membranes in the mouth are most commonly assessed and can be visualised by parting the lips of the horse – they should be uniformly pink and moist. Any colour change must be noted, as this can indicate deterioration in the horse’s condition.
A finger can be used to press the gum to blanch the tissue to assess the capillary refill time. The pressure should then be released, and the time taken for the tissue to return to a normal colour observed. A delayed return of colour to the mucous membranes (over two seconds) reflects reduced tissue perfusion and dehydration.
Temperature measurements in equids
The horse’s temperature is typically taken rectally. Caution should be employed when taking temperatures in horses due to the need to stand behind the patient. The end of the thermometer should be lubricated – this is especially important in neonates.
The RVN should […] make the patient aware of their presence by using their voice and running their hand slowly along the horse’s back and hindquarters
The RVN should stand at the patient’s side to take the temperature and make the patient aware of their presence by using their voice and running their hand slowly along the horse’s back and hindquarters. Then the base of the tail should be gently grasped and elevated. The lubricated end of the thermometer should be inserted about 2 inches into the rectum and held against the rectal wall to avoid contact with faecal material, which may cause an inaccurate reading. Once the thermometer alarm sounds, the thermometer should be carefully removed, the reading noted and the thermometer turned off and disinfected.
Conclusion
RVNs should be confident in carrying out a thorough clinical assessment of a wide range of patients. Results should always be recorded and communicated to the rest of the veterinary team. Changes to treatment or nursing care plans can then be made quickly and effectively, leading to gold-standard patient care and an optimum chance of recovery.
