ABSTRACT: We as veterinary professionals are often faced with challenging patients that require up-close and personal attention. A common scenario seen in veterinary practice is administering eye medications to an aggressive or difficult patient. This article discusses nursing considerations for these patients with a corneal graft and the use of a subpalpebral lavage system to aid us with our treatments. Perhaps with more options available we will not have to be so quick to sway towards enucleation for these aggressive patients.
Introduction
Patients required to undergo surgical repair for corneal defects often present as an emergency and with a very fragile eye. There are various reasons the patient may be in need of a corneal graft including a descemetocele, a perforation, a foreign body or a corneal sequestrum. Corneal grafts can be constructed from a variety of materials, such as the patient’s own conjunctiva, porcine small intestinal mucosa, or healthy corneas of dogs that have been donated following euthanasia. At the Queen Mother Hospital for Animals, we have a limited bank of frozen corneas that have kindly been donated after gaining consent from owners. Although there are many reasons for surgically repairing a cornea with a graft, the nursing considerations for these patients remain the same.
Admission and preparation for surgery
On admission of the patient it is important to check with the owners if they have knowledge of what the patient’s temperament is like in regard to administering treatments and performing conscious procedures. If this patient has not presented as an emergency we may have already seen the patient in a consult prior to surgery and established a potentially aggressive nature. Before preparing the patient for surgery we should decide if the patient is calm enough for us to attempt intravenous catheter placement and blood tests should they be required. Some patients may be extremely aggressive when administering eye medications but will allow other procedures. If the patient is stressed or we already know the patient does not tolerate such procedures, we should then consider giving a pre-medication before proceeding. Some of these patients may be visually compromised and painful, which is a frightening situation in itself, and because of this we should take precaution if we have any concerns about the patient’s behaviour.
Care should be exercised during jugular venepuncture – the positioning required together with occlusion of the jugular veins can increase intraocular pressure (Turner, 2005). As we will be placing an intravenous catheter for the general anaesthesia we could consider obtaining blood samples from our catheter site to avoid jugular occlusion.
It is very important to keep ophthalmology patients calm and avoid stressful situations as much as possible; stressful situations will result in an increase in intraocular pressure. Situations which could increase intraocular pressure include coughing, barking (move the dog or place a blanket over the kennel door), pulling on the lead (use a harness or lead across the chest instead) and taking rectal temperatures (Turner, 2005). If we allow the intraocular pressure to increase in these patients, we are at serious risk of the fragile eye rupturing due to its already weakened state.
Post-operative care
Recovery can be the most critical phase of anaesthesia especially after intraocular procedures. Self-trauma may cause irreparable damage. An animal that could see prior to the procedure and is blind post-operatively may panic, as may an animal that was previously blind and has had its sight restored (Gould & McLellan, 2015). We must ensure the patient is fitted with an appropriate-sized buster collar and it is tied on securely (Figure 1). This will need to be done prior to waking the patient up from anaesthesia if we struggle to get close to the patient’s face. We should not allow access to toys if the patient usually shakes them around in their mouth and plays vigorously. Vigorous play can increase intraocular pressure, which should be avoided due to the fragility of the eyes. Thick bedding/pillows should not be given as the patient is likely to use them to rub the eye on. Typically, ophthalmic patients are most likely to rub their eyes during recovery and in the immediate post-operative period, when they must be closely monitored. In addition, they may experience a transient increase in irritation associated with the application of medication and the owner should be instructed to prevent them from rubbing (Gould and McLellan, 2015). The patient should always be walked out using a harness/chest lead and the buster collar must be kept on. Exercising should be limited to toileting only and the patient should not be allowed to run/jump up steps/stairs as this can also increase intraocular pressure. Signs can be placed on the patient’s kennel to inform all staff of the handling considerations required (Figure 2).
Figure 1. This buster collar is tied on behind the patient’s forelimbs to ensure it is secure
Figure 2. Example of signs that can be used on the patient’s kennel to inform staff of the animal’s needs
Administering treatment and the subpalpebral lavage system
If the owner has informed us on admission that the patient will not tolerate the administration of eye drops, it may influence the decision on whether a corneal graft is suitable for this patient. Following surgery the patient will be placed on antibiotic eye drops which are crucial for the recovery and success of the surgery. Commonly in equine ophthalmology patients, the use of a subpalpebral lavage (SPL) tube system is used. SPL systems are specialised ophthalmic catheters that allow the administration of liquid medication through the lumen of a long tube that runs from the withers into the eyelid and discharges the drug through a special footplate that sits in the conjunctiva of the upper or lower fornix. The injected solution(s) then mix with the tear film to medicate the cornea (Gilger, 2010; Figure 3).
Figure 3. A subpalpebral lavage system
It is possible to place an SPL system in the canine patient and they are very beneficial for owners with challenging pets. The SPL can be used for any ophthalmology patient receiving eye drops, they are not limited to corneal grafts only. The tube can be taped to the outside of the buster collar so that the medications can be administered without having to restrain the patient and get too close to the patient’s face (Figures 4 and 5). The patient will need to be sedated or under general anaesthesia for the placement of the SPL; this is why it is important to take a thorough history on admission including temperament so that we can determine the need for alternative medication administration methods post-operatively. The SPL can then be placed under the sam
e general anaesthesia as the ocular surgery.
Figure 4. The subpalpebral lavage system can be taped to the buster collar
Figure 5. The subpalpebral lavage system can be taped to the buster collar
A volume of 0.1-0.2 ml of each medication is typically administered at each dose, and at least five minutes should elapse between the administration of each medication, which are injected individually (Maggs, Miller, & Ofri, 2017). After the medication has been injected through the needle free port, it should be chased with 0.4 ml of air to allow the medication to reach the footplate sitting in the conjunctiva. The patient may or may not react following the administration of the medication, but generally it is tolerated extremely well.
Properly managed SPL tubes can remain in place for a month or more. Catheter caps should be cleaned frequently with an alcohol wipe and replaced every two or three days. The injection assembly can be retaped as necessary (Gilger, 2010).
As well as an array of eye medications, the patient is likely to be sent home with oral NSAIDS. Tablets in the food is the preferred method and may be the only method if the patient is aggressive or difficult. However, if the tablets need to be administered directly, bear in mind that this might be painful for the patient. In a fully opened mouth, the vertical ramus of the mandible impinges on the retrobulbar tissues, which can be very painful in certain diseases (Turner, 2005).
Of course, enucleation may be the most appropriate course of action in some cases, and the decision can be owner-dependent. Owners are often reluctant to consent to enucleation on aesthetic grounds or because of their perception that the eye is not painful or retains some vestige of visual function (Gould & McLellan, 2015). For these owners reluctant to enucleate, the SPL system can be very helpful if their animal is challenging to medicate. We may also be in favour of saving an eye if the other eye is compromised. For example, the patient could have bilateral keratoconjunctivitis sicca and be at risk of future corneal ulcers developing, or the patient may only have one eye when presented to the veterinary clinic.
Conclusion
Although SPL systems are not commonly used in small animal practice, they are extremely suitable for our aggressive canine ophthalmology patients and should be considered when making a decision on surgery and treatment for these cases. They are simple to use and compliant clients may feel happy enough to use them at home with the correct knowledge and advice. This will allow our potentially stressed patients to get home quicker. The risks and complications that can occur with an SPL system such as corneal ulceration if it is not placed correctly or leakage of drops due to a break in the tubing, I feel, far outweigh the benefits if it is successful, and these complications are uncommon.
Disclosure statement
No potential conflict of interest was reported by the author.
Author
Sian Woodham-Davies RVN
Sian qualified as a veterinary nurse from the College of Animal Welfare in 2012 and is currently working at the Queen Mother Hospital for Animals in the Ophthalmology department.
Email: swoodhamdavies@rvc.ac.uk
References
Dugan Veterinary. (2018). Eye lavage kit/SPL [online]. Retrieved from http://www.dugganvet.ie/productsvet/ product/eye-lavage-kit-spl
Gilger, B. C. (2010). Equine ophthalmology (2nd ed.). St. Louis, MO: Elsevier:
Gould, D., & McLellan, G. (2015). BSAVA manual of canine and ophthalmology (3rd ed.), Gloucester, UK: BSAVA.
Maggs, D., Miller, P E., & Ofri, R. (2017). Slatter’s fundamentals of veterinary ophthalmology (6th ed.). St. Louis, MO: Elsevier.
Turner, S. (2005). Veterinary ophthalmology:A manual for nurses and technicians. London, UK: Butterworth Heinemann Elsevier.
Veterinary Nursing Journal • VOL 33 • September 2018