Clinical parameters

Note that these are meant as a guide only and normal animals can vary outside these ranges; they should be used as part of a full physical examination, and interpretations made in conjunction with other significant findings.

Temperature

Normal temperature

Adults & foals: 37.5 - 38.6° C (99.5 to 101.5°F )

Environmental factors can affect the readings by 0.5 - 1° C/F, with horses tending to have higher temperatures in warm weather. Exercise, stress or excitement will raise temperature as well.

Taking temperature. The best way to take the horse's temperature is rectally. Ensure the thermometer is well lubricated prior to inserting it. Stand next to the hind limb, pull the tail towards you and slide the thermometer in the rectum. Direct the tip to one side, so as to gently press it against the rectal wall in order to avoid faecal balls as these could give a false reading. Allow 2-3 minutes for the thermometer to record the temperature, to get the most accurate reading.

Heart rate (HR)

Normal resting heart rate in Beats per minute (bpm)

Adult: 38 - 40 bpm

2 years old: 40 - 50 bpm

Yearlings: 45 - 60 bpm

Foals: 70 - 120 bpm

Tachycardia

Maximum heart rates can exceed 180 beats per minute during strenuous exercise, but higher rates (tachycardia) of above 60-80bpm is a sign of cardiovascular compromise.

Reasons for this may be: stress, fear, pain and excitement (although the increase in HR will only be transient) or haemorrhage, peripheral pooling, severe infections (septicaemias), strangulations and infarcts of organs/tissues.

The most common cause of elevated resting heart rate is colic or intestinal pain. Such pain can cause mild to severe elevations, and the degree of increase can be a sign of the severity of the colic.

Auscultation. The HR can be taken with a stethoscope placed over the cardiac region (located behind the point of the elbow) or by feeling for a pulse (taken from the area under the jaw, from beneath the tail bone, or from the fetlock area at the level of the sesamoid bones)

Respiratory rate (RR)

Normal respiratory rate in respirations per minute (rpm)

Adult: 8 - 15 rpm

Neonatal foal: 20 - 40 rpm

Newborn foal: 60 - 80 rpm

A horse's respiration rate increases with hot or humid weather, exercise, fever, pain or when there are underlying infectious/inflammatory conditions causing the horse to reduce the depth of each breath, and thus increase the speed (tachypnoea). As a rule of thumb, the respiration rate should NEVER exceed the pulse rate. A horse should also spend equal time inhaling and exhaling. You should wait for the horse to be calm or at least 30 minutes after exercise, before checking the respiratory rate at rest to obtain a true reading.

Auscultation. The respiration rate can be calculated watching the belly of the horse rise and fall, or by placing the stethoscope over the trachea or a hand over the nostrils.

Body condition score

This is a visual tool which can help assess both the amount of fat and muscle of a horse, and can be used in conjunction with weights or weigh tapes, or as a single estimation when these are not accessible.

There are two recognised scales of visual assessment of Body Condition Scoring. The UK system uses a 1-5 scale (with 1 being emaciated and 5 overweight) while the American system (based on Henneke et al 1983) grades horses 1-9, giving the assessor greater flexibility and detail for the score given.

The neck, ribs and rump need to be looked at and felt in order to assess the horse's overall condition and level of body fat which provides an indication of the calorie intake and expenditure of the horse in question.

As a guide, a Body Condition Score of less than 4 would indicate that the horse's minimum calorie requirements are not being met by its diet, whilst one of more than 6 would indicate that its diet is supplying more calories than the horse requires.

Pain also increases caloric consumption, and some disease (e.g. dental and parasitic) directly negatively impact on calorie intake. Therefore BCS can de a good guide of a horse's health status too.

American body condition score explained

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Figure 2

UK body condition score explained

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Figure 4

(Images from: https://www.baileyshorsefeeds.co.uk/body-condition-scoring)

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