Chronic kidney disease (CKD) is defined as a progressive and irreversible loss of renal function over a period of 3 months or longer (Polzin, 2011). Marino et al (2014) established that 50% of 86 randomly selected cats, recruited from a veterinary practice, showed signs of CKD. This is considerably higher than the 30% incidence level previously reported in the literature (Lulich et al, 1992). The difficulty in detecting early stages of kidney disorder may mean that the actual percentage is much higher within the feline population.
Causes of CKD
CKD may be influenced by genetic, individual and environmental factors (Jepson, 2016). Decline in kidney function is considered normal in ageing animals (Polzin, 2011), however incidences of CKD in much younger patients indicates that age is not the only influencing factor. One suggested theory is that following an initial insult to the kidney, resulting in nephron damage, the kidneys try to compensate for the loss of function, resulting in further damage and nephron loss (Finco et al, 1999).
Clinical signs of CKD
The common clinical signs of CKD are listed in Box 1.
CKD can result in anaemia following a reduction in erythropoietin production, the hormone associated with red blood cell production in the inner renal cortex and outer medulla (Quimby, 2016). Hypokalaemia is another potential outcome characterised by muscle weakness, inappetence, anaemia and lethargy. Supplementation with potassium via the diet, oral potassium gluconate, or intravenous potassium chloride is suggested (Polzin, 2011). Hyperphosphataemia occurs as the kidney struggles to excrete phosphorus. High levels of circulating phosphorus leads to the development of secondary hyperparathyroidism, due to an increased secretion of parathyroid hormone (PTH) (Polzin, 2011). Increased mortality in humans, cats and dogs with CKD has been linked to high serum phosphorus concentrations (Boyd et al, 2008) so dietary management is an important consideration. Hypertension is commonly seen in between 20–65% of cats with CKD (Quimby, 2016).
Diagnosis and prognosis
Kidney disease can be diagnosed using a combination of blood evaluation, urinalysis, medical history and physical examination, including palpation of the kidneys to assess size and shape. Achieving a diagnosis in early kidney dysfunction can be difficult, when changes in blood parameters may not be detected until 75% of kidney nephron function has been lost (Hughes et al, 2002).
Finding accurate reliable data on average survival times for cats diagnosed with chronic renal failure is a challenge as some cats will undoubtedly be prematurely euthanased at the request of the owner for financial reasons or as a reaction to the perceived time commitment required to care for their pet as the disease progresses. Boyd et al (2008) conducted a retrospective study examining survival times from the point of diagnosis for 211 cats assigned to four different stages of CKD, using the International Renal Interest Society (IRIS) classification system (Table 1). Cats in stage one were excluded as they were not considered to have renal failure at that time. Cats that were diagnosed early (classed as stage two) lived up to 8.5 years from diagnosis (median of 3.15 years or 1151 days). Cats classified as stage three at diagnosis survived for an average of 1.86 years (679 days) but with some surviving up to 5.75 years. Cats in stage four kidney disease had a median survival of only 1.16 months (35 days). Overall median survival time was calculated as 2.1 years (771 days) from the time of diagnosis.
| Stage | Serum creatinine mg/dl (μmol/litre) |
|---|---|
| 1 | <1.6 (<140) |
| 2 | 1.6–2.8 (140–250) |
| 3 | 2.9–5.0 (251–440) |
| 4 | >5.0 (>440) |
Treatment
CKD is ultimately a progressive, irreversible disease. Early diagnosis and treatment may slow the rate of progression and positively impact on quality of life and life expectancy (Polzin, 2011). The ‘NEPHRONS’ approach to treatment for CKD (Figure 1) has been proposed by Bartges (2012) as a focused treatment strategy to correct imbalances commonly seen with the disease process.
Nursing care during hospitalisation
Ideally patients with CKD will be cared for in the home environment until their natural death or euthanasia. They may require temporary periods of hospitalisation to help them through a crisis point or when they become so unwell that the owner is unable to care for them at home (Figure 2). Patients may become ill due to chronic kidney malfunction, or because of comorbidities such as an acute case of gastroenteritis.
The role of the veterinary nurse in providing care to cats with CKD has been considered, in line with the Orpet and Jeffrey Ability Model (Orpet and Welsh, 2011). A holistic approach should be employed, considering all individual needs, for example a patient may also have osteoarthritis, or hyperthyroidism related to ageing. Factors such as lifespan, the owner's feelings about the care they wish their pet to receive, and their ability to pay for services will impact on the delivery of care. Table 2 highlights some of the likely challenges faced.
| Ability — is the animal able to… | Challenges in chronic kidney disease (CKD) |
|---|---|
| Eat? | Vomiting, may be anorexic. Initial aim is to encourage patient to eat. Specialist renal diet may be recommended. If so renal diet should be introduced gradually, preferably once the patient is back at home. |
| Drink? | Polydipsia occurs as a compensatory mechanism. Dehydration is possible especially if vomiting is present. Access to water at all times is essential. Intravenous fluid therapy may be required. |
| Urinate? | Polyuria is likely as the kidneys' ability to concentrate urine declines. Further exacerbated if patient is receiving intravenous fluid therapy. Urine volume must be closely monitored as the kidneys' ability to process volumes of fluid may be compromised. |
| Defecate? | Patients may be constipated and so careful monitoring is required. Use of enemas may be indicated. |
| Breathe normally? | Patients receiving intravenous fluid therapy should be monitored carefully for any changes in breathing, in case of over perfusion. |
| Maintain body temperature? | Patients may not be mobile, negatively impacting on their ability to regulate their own body temperature. Weight loss may be an issue. |
| Groom and clean itself? | Intravenous fluid therapy administration may interfere with grooming behaviour. A buster collar in cases of patient interference would disrupt grooming further. |
| Mobilise adequately? | Patient may be weak or collapsed. |
| Sleep and rest adequately? | May be stressed due to hospital environment, proximity to other patients and separation from owner/family members. |
| Express normal behaviour? | Illness may interfere with ability to express normal behaviour particularly if mobility is compromised due to ill health or fluid therapy administration. |
Medication
Veterinary nurses will be involved in the administration of medication, under veterinary direction, in line with Schedule 3 of the Veterinary Surgeons Act 1966. Clinical signs such as nausea, vomiting and oral and gastric ulceration may be managed by use of histamine (H2) blockers like ranitidine to limit gastric acidity, antiemetics such as metoclopramide and sucralfate as a mucosal protectant (Polzin, 2011), although sucralfate is currently unavailable due to a manufacturing interruption. Veterinary nurses will be involved in administration of fluid therapy under the veterinary surgeon's direction (Figure 3). ACE inhibitors such as enalapril and benazepril and calcium channel blockers (e.g. amlodipine) may be indicated for management of hypertension, along with regular blood pressure monitoring (Polzin, 2011).
Nutritional support
Dietary management of CKD offers an effective way to limit the rate of disease progression and commercially prepared renal diets provide a convenient method of managing nutritional intake. Reduced levels of phosphorus is recommended to prevent or treat existing hyperphosphataemia. Low levels of high biological value protein is required to prevent loss of lean body mass while avoiding contributing to uraemia and reduced levels of sodium to reduce incidence of hypertension. A pH-neutral renal diet may improve metabolic acidosis (Polzin and Churchill, 2016). Elliot et al (2000) compared the survival time in 50 cats that were fed either a renal diet or remained on their own food. Cats fed the veterinary diet (n=29) survived longer than their counterparts (n=21) with a median of 633 versus 264 days. While this offers support for the success or use of renal diets for CKD, it must be noted that veterinarians in the study knew which cats were assigned to which diet which may have influenced the way they were treated. A randomised double-blind placebocontrolled method would have strengthened the validity of the findings.
Renal diets should be introduced gradually to cats to avoid gastrointestinal upset, and to encourage patients to accept the dietary change offered. Cats have a tendency to neophobia, a dislike of novelty, that extends to food that they have not encountered before (Bradshaw et al, 1996). Mixing increasing amounts of the renal diet with the normal diet may help. A renal diet should not be fed exclusively, in case the patient refuses to eat it. Achieving adequate nutrition is important. If anorexia is seen assisted feeding via a nasogastric tube may be required (Polzin, 2011).
Supporting owners to provide care at home
The focus of the veterinary team will be ensuring that the patient receives the prescribed treatment as well as monitoring the welfare of the patient throughout the disease trajectory. If the patient is not hospitalised, owners will need to be supported in providing care in the home environment (Figure 4). A registered veterinary nurse (RVN) would be ideal, with their experience of dealing with emotional situations. A student veterinary nurse would also be suitable, as long as they are able to provide accurate advice, and are confident and competent at communicating with owners. The level of support that pet owners require following diagnosis of a chronic disease, will vary. The time owners have to dedicate to caring for their pet, around other commitments such as parental responsibilities, or employment status, could be a limiting factor. The owner's ability to deliver care must also be considered. Owners with physical or mental disability may require additional support, and consideration of support networks available to the owners is advisable, both in terms of their immediate social network and other professional agencies such as social workers.
Palliative care
Palliative or hospice care begins when achieving a full recovery becomes unrealistic (Villalobos, 2011). It provides a third option between implementation of prescribed treatment strategies, and immediate euthanasia and is usually carried out within the home environment (Figure 5). The aim is to minimise suffering until a natural death occurs, or the pet requires euthanasia. Gregerson (2016: 274) describes hospice care as the ‘preparation, protocols and ample time and support of both the patient and the family while they are coming to terms with their impending loss’.
The prognosis for patients diagnosed with CKD needs to be communicated sensitively to the owners, who may not want to accept the information. While the veterinary surgeon will be delivering this news, the veterinary nurse has a role to play in communicating with the owner, and offering them support. Terminal care will often require owners to make difficult decisions, they are likely to require support from the veterinary team at this stage (Shanan, 2011). This support will be beneficial during the period where anticipation of death occurs, as well as during and following the actual death of the pet. The needs of human family members need to be considered while being mindful that animal welfare should not be compromised.
Owners will have different ideas about quality of life. A decision about the timing of euthanasia is likely to be influenced by the owner's circumstances, in terms of their financial situation, culture, time constraints and their previous experience of death (Boyd et al, 2008). The patient's quality of life may not always be the primary consideration if overridden by the owner's beliefs or needs. This can be emotionally challenging for the veterinary team, if it is felt that the most ethical outcome is being avoided or delayed at a time when the patient is suffering.
Starting the process
Consideration of the owner–pet relationship is appropriate at this stage, as the quality and nature of the relationship will impact on the owner's decision to choose palliative care over the alternatives. The level of attachment of the owner to their pet will differ, as will the willingness of the owner to consider hospice care as an option. The wishes of the owner should be respected at all times, even when their views do not align with those held by the veterinary team. Veterinary professionals need to be aware that not all owners will be confident at providing palliative care at home, performing the techniques required such as administration of medication. Shearer (2011) recommends demonstrating techniques required to the owner, and then requesting that they demonstrate it back so that the veterinary team can assess their level of competence, and the likely success of the planned homecare regimen. Clear communication between the veterinary nurse and owner is key, particularly when discussing medication regimen (Figure 6).
Owners will be influenced by previous experiences of pet ownership, including pet loss and the circumstances of their deaths. An end-of-life care plan must consider how well the patient tolerates the prescribed treatment, and any further tests that may be required to monitor the rate of deterioration (Shearer, 2011). It could be considered unethical to continue collecting regular blood samples from a terminally ill patient who finds the procedure stressful.
Use of an illness trajectory (Table 3) may help the owner to visualise how the disease is likely to progress over time (Murray, 2005). This allows them to make an informed decision about the options available. CKD is considered to fit in the second trajectory category, as a chronic condition requiring an increasing commitment to care, as the kidney function deteriorates and clinical signs worsen. Owners therefore need to be aware that their cat is likely to require more intensive nursing in the period immediately before their death. Figure 7 displays a five-step approach for planning individual hospice care.
| Category | Description | Example of conditions |
|---|---|---|
| First trajectory | A short period of decline before death is seen (weeks or months) | Neoplasia |
| Second trajectory | A chronic illness often followed by sudden death as the disease progresses. Level of nursing care will increase with time | Chronic kidney disease, liver failure, and congestive heart failure |
| Third trajectory | A prolonged progressive deterioration of a condition. |
Degenerative myelopathy and cognitive dysfunction |
Supporting the owner following the loss of the patient
Emotional support for the owner should start from the point of diagnosis with a life-limiting disease like CKD. It should continue throughout the care process and after the death of the pet. Other professionals such as social workers, psychologists, and bereavement counsellors may enhance the provision of support alongside the veterinary team, helping families with planning for the future including preparing for the financial implications of care (Shearer, 2011).
After the death of a pet, owners should be offered bereavement counselling. Veterinary staff should be able to provide information to support surviving pets that display behavioural changes following the death of their companion.
Conclusion
Veterinary nurses play an important role in caring for patients with chronic kidney disease, and supporting their owners, to allow them to provide the care required in the home environment. This support should extend to emotional support, as the owner prepares for the loss of their pet, during the dying process and immediately following the death. For owners, being given the opportunity to care for their pet in their final days may be cathartic and pave the way for the healing process. Consideration should be given to companion animals within the household and the potential impact on them.