Measuring a senior pet's quality of life with a scale

Judging from memory is vulnerable to three known distortions. The first is gradual accommodation: we lower the sofa, move the bowl, shorten the walk, and never register that these are all adaptations to a loss. The second is selective sampling: we judge at the moment the animal is most responsive, usually when we come home, and not during the hours it sleeps or struggles to stand. The third is wishful reading, which turns every small improvement into a reversal of the trend.

A scale fixes very little of this if it is completed once. Its value comes from repetition: the same questionnaire, the same items, the same times, for weeks. At that point the single score matters little and the slope of the curve matters a great deal. It is the same logic as a weight curve or serial blood glucose: nobody decides on an isolated value.

The most widely used quality of life scale in veterinary medicine is the seven item tool known by the acronym HHHHHMM, first proposed in oncology and later adopted in palliative care for dogs and cats. Each item is scored from 0 to 10, where 10 is the ideal condition, for a maximum of 70 points. The authors point to a total around 35 as the boundary below which quality of life is no longer considered acceptable and the care plan needs revising.

Other scales are in use, including an eight item version that adds respiration and the caregiving burden on the family as explicit entries. The labels change, the logic does not: separate items, a numeric score, repetition over time. Which scale you pick matters less than the discipline with which you use it, provided you do not switch halfway through, because two different tools do not produce comparable numbers.

The last item of the scale, the ratio of good days to difficult ones, is the most informative and the easiest to distort from memory. The method that holds is trivial: every evening the day gets one label, good or difficult, according to a criterion decided in advance and written down. The criterion has to be observable, for example that the animal ate unaided, stood up without help and sought contact at least once.

1. Agree in advance with your vet on the three conditions that make a day good for this particular animal.
2. Record the label every evening at the same time, without reconstructing missed days from memory: a missing day stays empty.
3. Every Sunday count the difficult days of the week and record only that number, not a comment.
4. Complete the full scale once a week, always on the same day and with the same yardstick.
5. Ask a second person in the household to score independently once a month and compare the two totals.

Comparing two independent scorers is the simplest quality control there is. If the two totals differ by more than ten points out of seventy, the problem is not the animal but the definition of the items: at least one question is being read differently and needs rewriting in more concrete terms before you carry on.

A weekly score only becomes meaningful after four or five readings. At that point the possible trajectories are few and recognisable at a glance from the chart, with no statistics needed.

The most useful distinction is between a slow decline and a sudden drop. A drop within forty eight hours rarely represents the end of a trajectory: more often it is dehydration, acute pain, a urinary infection, a hypoglycaemic episode or a side effect of a recently started medication. A steady decline over months is the pattern that deserves to be met with a conversation booked in advance, not with an emergency call.

A scale achieves little if the score is not tied in advance to an action. The way to make it operational is to write down, while the animal is still relatively well, which thresholds trigger which decision. The thresholds are agreed with the vet and put in writing, because at the moment they are reached nobody is in the best position to set them.

• Review threshold: a total falling below an agreed value for two consecutive weeks books a visit rather than a wait.
• Single item threshold: a score of 3 or less on one item, pain for instance, carries weight on its own even when the total stays high.
• Difficult day threshold: more than three difficult days in a week, repeated for two weeks, is the most widely used trigger for reopening the discussion.
• The list of things that matter: three or four activities that make this animal recognisable, such as greeting at the door, asking for food, seeking the sun. When all of them disappear and do not return, the reading is clear.
• Emergency criterion: dyspnoea at rest, pain not controlled by current treatment, inability to stand. These are handled at once, not at the next scoring session.

The end of life conversation goes better when it is opened before it is needed. Bringing a series of scores to the consultation changes the nature of the discussion: you talk about a curve and agreed thresholds, not about an impression described out loud at a hard moment. The questions below are what make the appointment useful.

• Which current signs are still reversible and which belong to the progression of the disease?
• Which specific sign should I treat as the point where the treatment is no longer working?
• What can we add now for pain control, and within how many days should we expect a measurable effect?
• Which complications are foreseeable in this disease, and which of them count as an out of hours emergency?
• Does the practice offer home visits for the final stage, at which hours and with how much notice?
• What are the options for care of the body, and do they need deciding in advance or can they wait?

The last two questions are the ones most often postponed, and the ones that, left unasked, force rapid decisions at the moment nobody wants to make them. Asking about availability, hours and costs in advance brings nothing forward: it only makes the day it happens less confused.