Marie Rippingale1, Kate Lambert2, Cassie Woods3, Tamsyn Amos4, and Bonny Millar5
1 Bottle Green Training Ltd, Derby, UK
2 Pool House Equine Hospital, Crown Inn Farm, Lichfield, UK
3 Lower House Equine Clinic, Plas Cerrig Lane, Shropshire, UK
4 Priestwood Physiotherapy, Sitterlow Farm, Parwich, Ashbourne, UK
5 Equicomms, Norfolk, UK
17.1 Clinical Examination
Introduction
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 a treatment plan can then be created accordingly. A common approach includes following a system known as SOAPIER, which stands for:
Subjective: A subjective assessment is based on an opinion or feeling relating to an individual’s perspective or preferences. A preliminary assessment of the patient should be completed before handling the horse. This visual assessment should include aspects such as body condition, demeanour, temperament, posture, general coat condition and wounds or swellings [1].
Objective: An objective assessment is unbiased and is based on observable or verifiable facts. This includes assessing the patient’s vital parameters monitoring their food and fluid intake. A pain score should also be carried out. See Chapter 14 for more information.
Assessment: Results of the subjective and objective assessments should be documented during this stage. Ideally, these results would be documented on a clinical parameter record sheet or a care plan assessment record.
Plan: Nursing interventions are documented in this section. Ideally, these would be recorded on a nursing care plan. See Chapter 13 for more information.
Intervention: After the nursing care plan or treatment plan has been created, nursing interventions should be put into practice. These interventions should be documented.
Evaluation: The effectiveness of the nursing interventions needs to be evaluated. If goals, not objectives, were achieved or not achieved, this should be noted during this stage.
Re‐assessment: The care or treatment plan is reassessed and changed according to the results of the evaluation stage.
When using the SOAPIER system, both subjective and objective findings should be recorded clearly. A nursing care plan can then be formulated in conjunction with the veterinary treatment plan [1].
Clinical Parameters
The clinical parameters that should be assessed in equine patients include temperature, pulse, respiration (TPR), digital pulses, mucous membrane colour, capillary refill time and gut sounds (borborygmi) (Table 17.1). These readings should be taken twice daily; however, they may be required more frequently in critically ill horses.
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. Terms associated with clinical parameter readings can be found in Table 17.2. When conducting a clinical examination on a horse, it is important to order the stages of assessment to yield the most accurate results. For example, taking the temperature last as this may be stressful for the horse and lead to elevations in heart rate and respiratory rate.
Table 17.1 Normal clinical parameters for the horse, donkey and foal.
Source: Marie Rippingale.
Equid
Temperature (⁰C)
Pulse(beats per min)
Respiration (breaths per min)
Mucous membrane colour
Capillary refill time
Gut sounds
Digital pulses
Horse
37–38.5
24–40
8–16
Pale pink
>2 secs
Noise present in all 4 quadrants
Nothing abnormal detected (NAD)
Donkey
36.5–37.8
36–52
12–38
As above
As above
As above
As above
Foal (1 month of age onwards)
37.7–38.7
60–80
20–40
As above
As above
As above
As above
Table 17.2 Terms associated with clinical parameter readings in the horse.
Source: Marie Rippingale.
Term
Meaning
Associated conditions
Hyperthermia
High temperature
Infection
Hypothermia
Low temperature
Shock, general anaesthesia
Tachycardia
Increased heart rate
Pain, infection, stress
Bradycardia
Decreased heart rate
Shock
Tachypnoea
Increased respiration rate
Pain, infection, stress
Bradypnoea
Decreased respiration rate
Shock
Dyspnoea
Difficulty breathing
Severe equine asthma (formerly known as recurrent airway obstruction or RAO)
Apnoea
Cessation of breathing
General anaesthesia and death
Cheyne‐Stokes
Alternating periods of deep, rapid breaths, followed by shallow breathing and apnoea.
Hypoxia and death
Hypoactive gut sounds
Reduced borborygmi
Intestinal impaction or torsion
Hyperactive gut sounds
Increased borborygmi
Spasmodic colic, colitis, or enteritis
Respiratory Rate
Normal Reading
Horse: 8–16 breaths per minute
Method
The respiratory rate can be counted by watching the abdomen move with each breath.
The number of breaths should be counted over one minute.
This can be done from outside the stable to avoid disturbing the horse.
An alternative method is to feel the expiratory breaths at the nostrils. However, some horses may find this stressful, which will elevate the respiratory rate and make it inaccurate [1].
The 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 (Figure 17.1).
The presence of laboured breathing should also be noted.
The horse has 18 ribs, with the lungs extending, when fully expanded, to the 16th rib. To identify the 16th rib, a straight line should be drawn from the point of the elbow up to the point of the hip. This will mark the caudal boundaries of the lung field to auscultate.
Figure 17.1 The thorax should be auscultated as part of a respiratory examination.
Source: Dr Francis Boyer.
The nostrils should be examined for evidence of nasal flaring and discharge, with any distinguishing characteristics noted.
Both nostrils should be checked to ensure that they have a free airflow.
Pulse Rate
Normal Reading
Horse: 24–40 beats per minute
Method
The arterial pulse is the difference between systolic and diastolic blood pressure waves and can be counted by palpation of any superficial artery [1].
The most common place to take a pulse rate 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 (Figure 17.2).
Figure 17.2 The pulse is most commonly taken using the facial artery.
Source: Dr Francis Boyer.
Once the artery is located with the fingertips, the pulse rate should be counted for one minute.
RVNs should be familiar with other locations for taking the pulse (Figure 17.3) in case the submandibular artery is inaccessible, for example, during surgery.
Other suitable arteries are:
Transverse facial
Lingual
Carotid
Saphenous
Coccygeal
Metacarpal and metatarsal
Digital
A normal pulse should be strong and regular. 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.
A pulse deficit is apparent when the pulse rate is slower than the heart rate. This is common in patients with atrial fibrillation (see Chapter 13).
Sinus arrhythmia is a normal finding where the heart rate increases during inhalation.
The jugular veins should be observed and palpated for distention, thickening or pulsing that may indicate cardiovascular disease or thrombosis (Figure 17.4).
Digital Pulses
Normal Reading
Horse: Mild or non‐palpable pulse
Method
In healthy horses, digital pulses should be hard to find.
Figure 17.3 Locations of the arterial pulses. (a) Diagram of the head showing the locations where pulses are palpable. Diagram of lateral (b) and palmar/plantar digital arteries (c).
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 (Figure 17.3).
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.
Figure 17.4 Jugular veins should be observed and palpated to check for abnormalities.
Source: Dr Francis Boyer.
It is important to monitor digital pulses in patients who are at risk from endotoxemia, as laminitis can occur as a secondary complication
Heart Rate
Normal Reading
Horse: 24–40 beats per minute
Method
Auscultation of the heart is a crucial component of a clinical examination.
The heart rate should be auscultated just behind the elbow in the axillary region (Figure 17.5).
Moving the forelimb forward can facilitate ideal positioning for the stethoscope.
A systematic examination involves listening to both sides of the thorax [1].
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 beats over 15 seconds can be counted and multiplied by four to give the beats per minute.
There are four heart sounds that can be heard, and these are designated S1, S2, S3 and S4 (Table 17.3).
The sound designated S4 is the first sound to be heard in the cardiac cycle.
The normal sequence when all heart sounds are audible is: S4, S1, S2 and S3, although frequently, only two or three sounds are heard [1].
The normal heart sounds something like b‐lup‐dup‐p, although often it is only S1 and S2 sounds that are identified making a ‘lup‐dup’ sound [1].
Close attention should be paid to murmur sounds or the presence of an arrhythmia.
Figure 17.5 The heart rate should be auscultated just behind the elbow in the axillary region.
Relates to the start of systole and the emptying of the heart [1]. This makes a ‘lub’ sound.
S2
Occurs as the semi‐lunar valves in the arteries close at the end of systole [1]. This makes a ‘dub’ sound.
S3
Sound made by the fast phase of blood flow into the ventricles during diastole (the filling of the heart) [1]. This makes a ‘d’ sound.
S4
Composed of the noise of the atria contracting just before systole begins and the closing of the mitral and tricuspid valves [1]. This makes a ‘b’ sound.
A murmur is described as any sound in the cardiac cycle that should not be present. An echocardiogram may be required to determine the cause of a murmur, which is of clinical significance.
An arrhythmia is described as an abnormal rhythm, and if clinically significant, an electrocardiogram (ECG) may be necessary to determine the cause.
Abdominal Auscultation
Normal Readings
Continual noise should be heard in all four quadrants. Gut sounds or borborygmi are recorded, as seen in Table 17.1. 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
Abdominal assessment and auscultation are critical in the examination of the horse. Most abdominal abnormalities in the horse are associated with the digestive system and involve a change in gastrointestinal motility [2].
The horse should be observed for abdominal distention and asymmetry on both sides of the abdomen.
Auscultation of the gastrointestinal tract is performed with a stethoscope across four quadrants:
Upper left: Left paralumbar to midflank (Figure 17.6).
Lower left: Left midflank to the ventral abdomen (Figure 17.7).
Upper right: Right paralumbar to midflank.
Lower right: Right midflank to ventral abdomen [2].
The ventral midline area can also be assessed.
Each quadrant should be auscultated for 1–2 minutes.
On the left side, large intestinal borborygmi sounds are less pronounced because the spleen sits transversely against the body wall and in front of the intestines.
Time should be spent auscultating the lower left quadrant as this is the area where the pelvic flexure sits (see Chapter 4 for more information).
The pelvic flexure is a common site for impactions, and these can occur commonly as a secondary complication in hospitalised horses. Any reduction in borborygmi in this area should be noted and communicated to the case veterinary surgeon (vet).
On the left side, the small intestines are easier to auscultate and normally sounds like the quiet gurgling of a stream.
In a normal horse, loud, gassy borborygmi can be heard on the right side as gas moves through the liquid ingesta of the large colon.
Figure 17.6 Assessment of borborygmi in the upper left quadrant of the abdomen.
Source: Dr Francis Boyer.
Caecal emptying sounds, or ‘the caecal flush’, are unique and heard on the right paralumbar fossa. They sound like water flushing down a drainpipe and occur every 1–2 minutes in the normal horse.
In colic patients, gas can accumulate dorsally in the paralumbar fossa, and with enough distension, gut sounds can be heard cranially into the ribcage.
Decreased or complete cessation of gut sounds may suggest serious and detrimental changes to the intestine. This is often described as a ‘quiet’ abdomen. ‘Pinging’ high‐pitched sounds indicate trapped gas in the caecum or large colon and will often be associated with tympanic colic.
Hypermobile gassy and fluid gut sounds may indicate an episode of spasmodic colic, impending colitis or enteritis.
Mucous Membrane Colour and Capillary Refill Time
Normal Readings
Mucous membrane colour: pale pink
Capillary refill time: fewer than 2 seconds.
Figure 17.7 Assessment of borborygmi in the lower left quadrant of the abdomen.
Source: Dr Francis Boyer.
Method
Mucous membranes should always be assessed in good natural light.
The mucous membranes in the mouth are most commonly assessed and can be visualised by parting the lips of the horse.
The mucous membranes in the mouth should be uniformly pink and moist.
Any colour change must be noted, as this can indicate deterioration in the horse’s condition. See Table 17.4 for further information.
To assess the capillary refill time, a finger can be used to press the gum to blanch the tissue (Figure 17.8). 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.
Table 17.4 Mucous membrane colour and associated conditions.
Source: Marie Rippingale.
Term
Meaning
Clinical signs
Associated conditions
Cyanotic mucous membranes
Deoxygenated mucous membranes
Blue mucous membranes
Shock, severe equine asthma, heart failure
Blanched mucous membranes
Under perfused mucous membranes
White mucous membranes
Anaemia, hypotension, shock
Congested mucous membranes
Highly perfused mucous membranes
Bright red mucous membranes
Dehydration, endotoxaemia, sepsis
Jaundiced (icteric) mucous membranes
Increased bilirubin in blood stream
Yellow mucous membranes
Liver disease
Petechial haemorrhages
Focal haemorrhages
Red dots on mucous membranes
Disseminated intravascular coagulation
Figure 17.8 To assess the capillary refill time, a finger can be used to press the gum to blanch the tissue. The time taken for the colour to return should then be noted.
Source: Dr Francis Boyer.
Temperature
Normal Reading
Horse: 37–38.5°C.
Method
The horses’ temperature is typically taken rectally.
The result may be slightly lower than expected if the horse has just passed faeces.
Caution should be employed when taking temperatures in horses due to the need to stand behind the patient.
If the temperament of the patient is not known, a set of stocks can be used to reduce the risk of injury.
Figure 17.9 The thermometer should be inserted about 2 inches into the rectum and held against the rectal wall.
Source: Dr Francis Boyer.
A competent handler wearing PPE should restrain the patient.
The end of the thermometer should be lubricated. This is especially important in neonates.
The RVN should stand to one side of the patient to take the temperature.
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 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 [1] (see Figure 17.9).
Once the thermometer alarm sounds, the thermometer should be carefully removed, the reading noted and the thermometer should be 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 a high standard of patient care and an optimum chance of recovery.
17.2 Administration of Medication
Introduction
The administration of medication is often delegated to RVNs by the treating vet. Therefore, RVNs should have a good knowledge of the effects of these medications, the correct routes for administration and how to recognise and manage complications safely if they occur.
Oral Medication
Oral medications include liquids, suspensions, solutions and syrups. The simplest way to give oral medication is to mix it into feed. Some patients may need extra encouragement to eat medication; if this is the case, succulents such as garlic, carrots and apples may be offered. Adding molasses to the feed may increase palatability also. Feeds containing molasses may not be an option for horses on a diet, with laminitis or metabolic conditions such as pituitary pars intermedia dysfunction (PPID), also known as equine Cushing’s disease (ECD) and equine metabolic syndrome (EMS). For these patients, water from sugar beet pulp could be used; this has a low sugar content but will add flavour. Medications should only be added directly before feeding. Leaving medications in feeds for some time can cause the stability of the drug to change, which can affect the efficacy of the drug. Not all oral medications can be given in feeds; detomidine gel is an oromucosal gel that must be administered sublingually to be effective. RVNs should always read the manufacturer’s instructions before administering any medication.
How to Administer Drugs Using a Dosing/Catheter Tipped Syringe
Some horses may not eat medication that has been put in their feed, so the medication may need to be administered using a dosing syringe. The technique for this is as follows [3]:
A competent handler wearing appropriate PPE is essential for adequate restraint
After checking the mouth is empty, the tip of the syringe should be inserted into the mouth, pointing up towards the back of the tongue
The medication should then be introduced directly onto the tongue
The horse’s head should be held up, and its mouth should be carefully monitored to ensure the medication is not expelled and wasted
Aspiration of medication, which may cause aspiration pneumonia; however, this is rare.
Injury to nervous horses and/or their handler.
Topical Medication
Topical medications include creams, ointments, shampoo and gels.
When applying to the skin, ensure the area is cleaned prior to application.
Clipping may be required in some breeds to ensure good skin contact.
Gloves should be worn.
Advantages
Delivering a high concentration of medication locally can lead to a lower quantity of medication required overall compared to that required systematically to achieve the same effect.
Depending on the patient, topical medication can be easier to apply than oral medication.
Topical medications can be applied by an owner.
Potential Complications
Too much hair in the area can prevent good contact.
Horses may rub or lick topical medications off; if this is the case, light bandages, muzzles or a neck cradle may be required to prevent the horse from gaining access to the affected area.
Eye Drops/Ointments
Eye conditions may require medication to be delivered directly onto the corneal surface. It is crucial to ensure the tip of the application bottle or syringe does not come into contact with the corneal surface, as this can cause further trauma, and bacteria can be transferred from the applicator to the eye. Occular medications often require multiple applications throughout the day, so it is essential to make the experience as stress‐free and positive for the horse as possible. Otherwise, they can become head‐shy and start to resent treatment. Scratches, grooming and treats can be used to help the horse to develop a positive association with the treatment. General tender loving care (TLC) and grooming should be provided for every patient regardless of their condition to encourage interaction and promote psychological wellbeing.
Subpalpebral Lavage (SPL)
If horses strongly resent the application of eye medication or if frequent doses are required, then a subpalpebral lavage (SPL) may be placed. A SPL is an indwelling lavage system placed under the upper or lower eyelid; the lavage system is sutured to the skin, and the tubing is then threaded through the mane, so the injection port is at least midway down the horse’s neck. The injection port should be changed daily to minimise contamination [4]. The volume of medication administered can vary from 0.1 to 0.5 ml [4]. Air should be administered following the medication to ensure that it reaches the eye and does not sit in the SPL tubing. The horse should be observed for blinking or for the medication to be seen entering the eye. It is important to determine how much air is needed to follow the medication to ensure it reaches the eye. Both medication and air should be administered slowly through the lavage system so the horse does not become sensitised to it. Five minutes should be left between medications to allow time for the medication to be absorbed [4]. Rewards such as treats, scratches and/or licks should be given to the horse following medication to make this a positive experience for the patient.
Nursing Observations
Horses with eye conditions often need to be kept in a dark stable away from direct sunlight; if this is not possible, then an ultraviolet (UV) fly mask may be required to protect the eye. Haynets should be removed from the stable to prevent the horse from rubbing its eye, and a stable grill may be required to prevent rubbing on the stable door. Sometimes, the headcollar is left on the horse to facilitate catching. In these circumstances, the headcollar should be made of leather and be padded, especially around buckles and metalwork to prevent rubbing and the development of sores on the face. Specially designed eye masks are now commercially available for horses. They have rubber cups that further protect the eye, which can help to prevent rubbing.
Injectable Medication
Patient Restraint
For injections to be given successfully, safely and effectively, patient restraint should be considered. This will prevent excessive movement and help to avoid improper injection [5]. As a minimum, all horses receiving an injection should be restrained using a headcollar and lead rope. The handler should wear PPE such as a hard hat, steel toe‐capped boots and gloves. Treats or a lick may be offered to the patient if appropriate to help to make the procedure a positive experience. Extra restraint may be necessary in the form of stocks or sedation for fractious or needle‐shy horses. Each case should be evaluated on an individual basis. If sedation is required, this must be prescribed by a vet.
Drawing Up Medication
Medication must be drawn up carefully and aseptically. The following steps should be followed [5]:
Hands should be clean, and gloves worn. This will contribute towards reducing the spread of nosocomial infections and preventing contamination of the medication and injection site.
The following should be verified as correct:
Patient
Medication
Route
Dosage
Timing
Expiration date
Broach date
Storage of the medication prior to injection
If appropriate, the medication should be gently inverted to make sure it is mixed thoroughly.
An appropriate needle and syringe should be selected.
The needle should be attached to the syringe without contaminating the hub of the needle or the tip of the syringe. This will help to maintain asepsis.
The rubber bung on the medication should be disinfected using a gauze swab soaked in 70% alcohol (not appropriate for vaccines). This will help to reduce contamination.
The needle cap should be removed carefully. The needle should be inserted aseptically into the rubber bung on the bottle. The needle should not be touched as it is inserted into the bottle, as this could lead to contamination.
The correct amount of medication should be drawn back into the syringe. The needle and syringe should be carefully removed from the bottle.
The needle and syringe should be held vertically, and the syringe should be tapped to dislodge any air bubbles. These should then be removed.
Horses can tolerate 0.25 ml/kg of air before showing clinical signs. Even so, removing excessive air bubbles will help to reduce the risk of an air embolism developing, especially during an intravenous (IV) injection.
The amount of medication remaining in the syringe should be checked. More medication should be withdrawn if required.
Recapping needles is a hazard and should be avoided. The needle can be removed using artery forceps or using the lid of a sharps bin.
A new needle should be applied to the syringe.
The syringe should be labelled with the drug name, drug concentration, time and date. This will help to mitigate errors.
Intramuscular (IM) Injections
Sites for IM Injections
Note: Images for this section are to be used as a guide only. Each horse should be assessed individually when locating an appropriate injection site.
The main sites for IM injection in horses can be seen in Figure 17.10.
Trapezius muscle: The landmarks form a triangle 4″ above the dorsal border of the cervical vertebrae, 4″ cranial to the cranial border of the scapula and 4″ below the border of the crest of the neck [5] (Figure 17.11).
Pectoral muscle: Located in the cranial most part of the chest, craniomedial to the thoracic limbs [5] (Figure 17.12).
Gluteal muscle: The injection site can be found in the centre of a triangle formed by the tuber coxae, tuber ischium and tuber sacrale (Figure 17.13).
Figure 17.10 Intramuscular injection sites in the horse.
An 18–21 g × 1.5‐inch hypodermic needle and a syringe should be used in most horses [3]. See Table 17.5 for details of needle sizes.
A 20 g × 1‐inch needle should be used for foals [3].
Ideally, no more than 5–10 ml should be delivered per injection site [6]. This is not the case for gluteal muscles. Any amount up to 20 ml can be administered into the gluteal muscle. However, if the volume of medication is larger than 20 ml, the medication should be split into more than one location [4].
Method for IM Injections
Restraint of the horse is important to ensure the safe administration of medication.
The injection site should be swabbed with a suitable skin preparation to remove any superficial contamination (Figure 17.14).
Tapping the horse with the backside of your hand two to three times will desensitise the area first and make the injection less of a shock to the horse (Figure 17.15). This will make the procedure safer as the horse is less likely to react to the needle.
For injection into the gluteal muscle, the person administering the injection should stand as far cranially and close to the horse as possible to prevent them from being kicked.
The needle should be inserted without the syringe attached (Figure 17.16). Once the needle is in, the syringe should be attached and aspirated. This is ESSENTIAL to ensure no blood vessels have been penetrated (Figure 17.17).
If no blood is visible, the medication can be injected. If blood is present on aspiration, DO NOT INJECT; the needle should be redirected, and the syringe aspirated again.
If no blood is present on aspiration, it is safe to inject the medication.
Once half of the medication has been injected, the syringe should be aspirated again to make sure the needle is still in the correct place (Figure 17.18). If no blood is present, the full dose of medication can then be administered.
Once the medication has been administered, the needle and syringe should be removed.
The injection site should be swabbed and checked for any bleeding.
Figure 17.14 The injection site should be swabbed with a suitable skin preparation to remove any superficial contamination.
Source: Dr Francis Boyer.
Figure 17.15 Tapping the horse with the backside of your hand two to three times will desensitise the area first and make injection less of a shock to the horse.
Source: Dr Francis Boyer.
Figure 17.16 The needle should be inserted without the syringe attached.
Source: Dr Francis Boyer.
Figure 17.17 Once the needle is in, the syringe should be attached and aspirated to check for venepuncture.
Source: Dr Francis Boyer.
Figure 17.18 Once half of the medication has been injected, the syringe should be aspirated again to make sure the needle is still in the correct place.
Source: Dr Francis Boyer.
If the volume of medication is bigger than 20 ml, the medication can be split into more than one location. Alternatively, with a gluteal injection, the needle can be redirected halfway through the injection. Following re‐direction, the syringe must be aspirated to check for venepuncture. The muscle group and side used for the injection should be recorded. This is important to facilitate the rotation of muscle groups, to prevent heat or swelling at an injection site.
Potential Complications
Injury to horse or handler.
Inadvertent puncture to other structures, especially blood vessels, can cause severe reactions, including seizures which is classically associated with the injection of procaine penicillin [6].
Inadvertent puncture of vertebrae or nuchal ligament (neck injections).
Inadvertent puncture of the sciatic nerve (in the hind limb).
Localised swelling, especially when injecting into the pectoral muscles.
Pain, stiffness or abscess formation at the injection site [3].
Abscess formation is an occasional complication. A disadvantage to using neck or gluteal muscles for injection is that should abscessation occur; these are more difficult sites to drain [6].
Muscle soreness is a common complication. Rotating the sites used can avoid this, especially if the medication is to be administered twice daily [6].. If muscle soreness occurs, no further injections should be administrated at that site, and topical heat packs might provide some relief for this problem [6].
The horse’s behaviour and temperament should be considered. Sometimes, it is not possible or safe to inject horses via the IM route. In these cases, oral or IV medication can be administered instead.
Anaphylaxis. This can occur in the form of a seizure. If this happens, the handler and RVN should consider human safety as a priority. A vet should be alerted immediately.
Nursing Observations
Reaction after medication, ranging from urticaria (itchy skin lumps/rash) to seizures and/or collapse.
Sore injection sites following repeated injections: if this is the case, then a change in muscle groups and/or hot packing of the sore area can be implemented.
The horse’s behaviour should be considered. If the horse is becoming more difficult to inject as time goes on, then positive enforcement, clicker training or possibly changing the route of medication may be required.
Handler Observations
While restraining the horse for an injection, the handler should look out for the following signs of a reaction:
Dilation of the pupils
Rapid sedation/excitement
Muscle twitching
Horse’s head quickly lifting into the air followed by excitable behaviour
The handler should inform the vet or RVN of any behavioural changes straight away, to allow the handler and the person giving the medication time to move to a safe place. A vet should always be informed if a change in behaviour occurs.
Intravenous (IV) Injections
Sites for IV Injections
Jugular vein: Most commonly used vein for IV injections. Jugular veins are large and easily accessible. If a complication occurs in one jugular vein, the lateral thoracic should be used as an alternative rather than the other jugular vein. If both jugular veins become compromised, this can disrupt venous drainage to the head, which can have life‐threatening consequences.
Lateral thoracic: Commonly used as an alternative to the jugular vein, especially if a complication has occurred. Easy to access and attach IV fluids to in critically ill patients.
Cephalic vein: Rarely used due to location. More commonly used in foals than in adult horses.
Saphenous vein: Rarely used due to location and health and safety implications.
Figure 17.20 The needle was inserted at an angle of 30 degrees to the skin pointing upwards.
Source: Dr Francis Boyer.
Blood should be seen, indicating correct needle placement. The blood should be dark in colour and slow flowing (dripping) (Figure 17.21). If bright red, fast‐flowing (spurting) blood is seen, this is an indication that the needle is in the carotid artery (Figure 17.22).
If the needle is thought to be in the carotid artery, THE MEDICATION SHOULD NOT BE INJECTED; the needle should be removed, and pressure should be applied. Another injection site should be selected for the medication.
Once the needle is confirmed to be in the vein, the syringe should be attached and aspirated to ensure the needle is still in the correct place before injecting the medication (Figure 17.23).
The medication should be given slowly, and the syringe should be intermittently aspirated to ensure that the needle is still in the correct place.
Figure 17.21 Blood should be seen indicating correct needle placement. The blood should be dark in colour and slow‐flowing (dripping).
Source: Dr Francis Boyer.
Figure 17.22 If bright red, fast‐flowing (spurting) blood is seen, this is an indication that the needle is in the carotid artery.
Source: Marie Rippingale.
Pressure can be applied once the needle is removed using a gauze swab or a gloved hand to prevent a haematoma (Figure 17.24).
Potential Complications
Injury of horse or handler.
Self‐injection. If this happens, medical attention should be sought immediately [7].
Inadvertent puncture of other structures, for example, the carotid artery. This often happens when a needle is inserted too deeply. Bright red blood will spurt out of the needle. Medication should never be injected into the artery, as this can cause severe reactions such as collapse and seizures.
Figure 17.23 Once the needle is confirmed to be in the vein, the syringe should be attached and aspirated to ensure the needle is still in the correct place before injecting the medication.
Source: Dr Francis Boyer.
Figure 17.24 Pressure can be applied once the needle is removed using a gauze swab or a gloved hand, to prevent a haematoma.
Source: Dr Francis Boyer.
Extravascular injection can cause pain, inflammation, infection and tissue sloughing [7].
Anaphylaxis can occur in the form of a seizure. If this happens, the handler and RVN should consider human safety as a priority. A vet should be informed immediately.
Nursing Observations
Swelling of the vein. This could be indicative of a thrombus.
Pain around the vein could result from a reaction to drugs or be a sign that some medication has been given perivascularly rather than intravenously.
Change in behaviour, such as increased and sudden levels of sedation, and seizures if the sedation is accidentally administered into the carotid artery.
Previous signs of catheter placement, scaring or trauma to the vein can make it more difficult to inject at that site.
Phlebotomy (Taking a Blood Sample)
Blood samples are most commonly obtained from the jugular vein in horses. The process follows the procedure for needle placement as described for IV injections above. There are two methods used for obtaining a blood sample: Using a needle and syringe and using a vacutainer system.
Needle and Syringe
Once the needle has been confirmed as being in the jugular vein, a syringe can be attached and aspirated so that blood flows back into the syringe.
The vein should be raised during this process.
If blood stops flowing at any point, the syringe should be disconnected, and the needle should be carefully re‐directed until blood flow is restored [7].
Once the blood sample has been obtained, the vein should cease to be raised and the needle should be withdrawn.
Pressure can be applied once the needle is removed using a gauze swab or a gloved hand, to prevent a haematoma.
The blood sample should then be quickly decanted into an appropriate vacutainer or sample pot.
Vacutainer System
Once the needle has been confirmed as being in the jugular vein, the vacutainer should be pushed firmly onto the piercing needle [7] (Figure 17.25).
Care should be taken not to move the needle within the vein.
Figure 17.25 A blood sample being taken using the vacutainer system.
Source: Rosina Lillywhite.
The vein should be raised until the vacutainer is full.
If blood stops flowing at any point, the vacutainer should be pulled off the piercing needle, and the sleeve and needle redirected [7].
The vacutainer should then be pushed back onto the piercing needle [7].
Once the blood sample has been obtained, the vein should cease to be raised and the needle should be withdrawn.
Pressure can be applied once the needle is removed using a gauze swab or a gloved hand, to prevent a haematoma.
Subcutaneous (SC) Injections
Method for SC Injections
SC injections are often given in the neck just in front of the scapula.
The injection site should be swabbed with a suitable skin antiseptic to remove any superficial contamination.
A handful of skin should be grasped, and a 21‐gauge × 1.5‐inch needle should be placed (with a syringe attached) into the base of the handful of skin (Figure 17.26).
The syringe should be aspirated to ensure a blood vessel has not been accidentally punctured. If no blood is seen, then it is safe to inject the medication.
Complications
The needle could be placed through the skin and out the other side
The injection can be difficult and slow in thick‐skinned horses.
Figure 17.26 Administration of a subcutaneous injection.
Source: Dr Francis Boyer.
17.3 Intravenous Catheter Placement
Introduction
IV catheters are commonly used in equine practice; however, this can lead to complications such as thrombus and thrombophlebitis. RVNs should be vigilant when placing IV catheters and monitoring catheter sites so that complications can be prevented.
Indications
Indications for placing an IV catheter include:
Fluid therapy (crystalloids, blood and or plasma): Placing an IV catheter allows the administration of large amounts of fluids over an extended period of time. See Chapter 14 for more information.
Drug therapy: Having access to an IV catheter reduces the need for repeated venepuncture if medication needs to be administered regularly throughout the day. This reduces trauma to the vein and is more pleasant for the patient.
Total parenteral nutrition (TPN): This requires the provision of a dedicated IV catheter, which must be treated aseptically.
Measurement of central venous pressure (CVP): Used to assess cardiac function and to monitor fluid therapy. A long saline‐filled catheter is advanced through the jugular vein into the right atrium, and the pressure is then measured.
Blood transfusions: IV catheters are used to facilitate blood collection and administration during a transfusion.
Points of IV Access
The jugular vein is most commonly catheterised as they are large and easy to access (Figure 17.27). If IV catheter complications occur in one jugular vein, catheterising the contralateral jugular vein is contraindicated due to concerns over disruption of venous drainage. Swelling of the head and cervical region can then lead to a life‐threatening airway obstruction. Other IV catheter sites used in the horse include the lateral thoracic (Figure 17.28) and cephalic veins, but these sites are more prone to catheter complications from patient interference and movement. Saphenous veins can be catheterised, but due to the location, catheter placement and handling may be dangerous [8]. The IV catheter site should be chosen carefully depending on the individual patient and the reason for placing the IV catheter.
Figure 17.27 A jugular catheter placed in a retrograde orientation.
The choice of catheter depends on several factors, including [8]:
Volume and rate of fluids
Type of fluid
Patient’s potential to develop a thrombosis
The expected duration of catheterisation
Finances
Catheter Material
IV catheters are available in a number of different materials, and these need to be considered before a choice is made. Different materials include:
Tetrafluoroethylene (Teflon): These are the most thrombogenic catheters and are prone to kinking and cracking with long‐term use. They are usually termed ‘short stay’ catheters and should only be left in situ for a maximum of 24 hours. Teflon catheters tend to be the cheapest.
Polyurethane: These are less thrombogenic than Teflon catheters as they are softer and more flexible. They are usually termed ‘long stay’ catheters and can be left in situ for up to 21 days if monitored and handled correctly. Polyurethane catheters are more expensive than Teflon catheters.
Silicone: These are the least thrombogenic of the IV catheter materials. They are long and flexible. Often used for over‐the‐wire catheters and can be left in place for one to two months if required (Figure 17.29). Over‐the‐wire catheters are most commonly used for critical care and patients requiring TPN. These catheters tend to be the most expensive.
All IV catheters are thrombogenic to a degree. So, careful selection is important to minimise the risk of complications.
Catheter Size
The size of the catheter should also be considered:
A 10–12‐gauge catheter is recommended for severely hypovolaemic adult horses and donor horses when giving blood for a blood transfusion. The disadvantage of this is that large bore catheters are more thrombogenic.
A 12–14‐gauge catheter is recommended for moderately hypovolaemic adult horses.
14–16‐gauge catheters should be used for horses requiring frequent medication.
16‐gauge catheters are sufficient for hypovolaemic weanlings and Shetlands or miniature horses [9].
Direction of Placement
There are two directions for catheter placement in the horse:
Retrograde (Figure 17.27): The catheter is placed ‘up the way’ or against the direction of blood flow. This technique minimises the risk of air embolism if the catheter or hub gets disconnected. This argument does not apply if the catheter is fitted with a haemostatic valve [8]. Retrograde placement can lead to catheter complications during high‐rate IV fluid administration due to increased turbulence of blood flow and irritation of the endothelium.
Antegrade (Figure 17.30): The catheter is placed ‘down the way’. Or with the direction of blood flow. This direction increases the risk of air embolism if the catheter of cap becomes disconnected. This direction of placement does however decrease the risk of catheter complications during high‐rate IV fluid administration due to decreased turbulence of blood flow and reduced irritation of the endothelium. This allows for more rapid administration of IV fluids [8].
There is no right or wrong direction to place an IV catheter in as long as all of the risks have been considered to inform the final decision.
Placing an IV Catheter
Equipment Required
Placing an IV catheter in an equine patient requires an aseptic technique. To facilitate this, all equipment should be prepared beforehand. Equipment required includes [10]:
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