Why observe several reflex actions together to measure animal vitality?

Philipchircop 2012

Why observe several reflex actions together to measure animal vitality? The short answer is that animals are whole beings; a summary collection of component parts and their interactions in response to stimuli.

Animals are constructed of biochemical and behavioral components that interact to form a whole; capable of responding to stressors. The interactions of stressors and behavior are also important for prediction of vitality impairment and survival. Reflex actions are fixed behavior patterns that include biochemical, muscle, organ, and nerve functions.

Efforts to identify factors that can control vitality and predict post-release survival and mortality of captured animals generally strive to identify single important variables. For example, temperature changes, injury, exhaustion, and hypoxia can control vitality and survival. For simplicity, single factors are statistically modeled as predictors for survival. Factor interactions are rarely considered because of their complexity.

Patterns of vitality impairment vary with species and contexts. Observing impairment of several reflex actions and possible injury in a defined context integrates the effects of multiple stressors, contexts, and their interactions on animal impairment and survival. Measurement of single reflex action impairment can miss the range of vitality that spans from excellent to moribund. 

Stoner 2012 (crabs)

Below are several examples of the cascading nature of impairment observed as individual reflex actions cease to function in a spectrum of stressor intensities. Reflex actions with higher proportion of impairment are impaired before those with lower percentage. Note that patterns of impairment vary with taxa and context.

Davis 2010 (walleye pollock, coho salmon, northern rock sole, Pacific halibut)

Stoot et al. 2013 (turtles)

Uhlmann et al. 2016 (plaice, sole)

Forrestal 2016 (triggerfish)

Forrestal 2016 (yellowtail snapper)

Danylchuk et al. 2014 (lemon shark)

McArley and Herbert 2014 (snapper)

Sampson et al. 2014 (mottled mojarra)

Stoner 2009 (Tanner crab, snow crab)

Stoner 2012 (spot prawn)

Observer bias and RAMP

Cognitive bias (The Daily Omnivore, 2012)

Subjective scores for animal behavior can be biased by observer opinions about experimental treatment differences and resulting outcomes (Tuyttens et al. 2014). The research paper title expresses a fundamental bias of human perception and belief: “Observer bias in animal behaviour research: can we believe what we score, if we score what we believe?” The problem is to separate belief from observation. This may be accomplished by clearly defining and adhering to consistent protocols for behavior observation and analysis.

RAMP relies on subjective scoring for presence or absence of reflex actions or injury types. Control fish have a suite of reflex actions that are consistently and clearly present when tested for. When an observer begins to notice the weakening or complete loss of a reflex action, that action is scored as absent (impaired). There will be variation among observers in the decisions about when reflex actions are impaired and bias will vary with experimental protocol. 

Because RAMP is an aggregate vitality impairment index summed from control reflex actions and potential injury types, a RAMP score includes the observer bias for each included reflex action and injury. Close correspondence of RAMP scores and mortality is noted at low and high scores because observers clearly know when fish are active and when fish are severely injured and impaired. Relationship of mortality and RAMP is more variable at intermediate levels of impairment and mortality in part because observer opinion about impairment is more variable. To reduce observer bias, RAMP for a species must be designed to include reflex actions and injury types that can be clearly separated into present or absent scores. Also experimental treatments can be administered without informing observers.   

Vitality of a stressed fish is readily observed. We are primarily seeing the activity, responsiveness, and injury presented by the animal. The most widely used vitality index in commercial fisheries is for the halibut fisheries of the northeast Pacific Ocean (AFSC Observer Manual 2015), based on Appendices S-X for trawl, pot, and longline fisheries.  For trawl and pot fisheries, three levels of vitality (excellent, poor, and dead) are scored by observing injury types and spontaneous activity, startle response to touch, and operculum clamping. For longline fisheries, vitality is scored by observing injury types. Mortality rates are assigned to vitality impairment scores using tagging experiments (Williams 2014).

Vitality impairment codes (Benoît et al. 2010).

Benoît et al. (2010) constructed a fishery vitality index with four levels of impairment (excellent, good, poor, moribund) that are scored by observing injury types, spontaneous body movement, startle to touch, and operculum clamping. Their vitality index and the halibut vitality index use the progressive increase of injury and impairment of activity to score vitality impairment. Benoît et al. (2010) corrected for observer bias by using a random effects term in their statistical model. 

Reflex actions scored for presence or absence in RAMP for snapper (McArley & Herbert 2014).

The RAMP vitality index alters impairment scoring to only include presence or absence of a larger number of injury and reflex actions. This shift attempts to introduce more information about activity and injury types that may be associated with mortality and to reduce decisions about degree of impairment for individual activity and injury traits. Impairment is observed as a progressive increase in the number of reflex actions that become absent and the number of injury types that become present when compared to control animals. Because observer bias can be introduced in scoring, observer protocols must be well defined with clear rules for presence or absence of traits. Observer judgements about correspondence between experimental treatments and outcomes could also be eliminated by careful experimental design.

Measuring and scoring vitality impairment

Associations between vitality impairment and mortality in Tanner and snow crab; Stoner et al. 2008.

At the risk of repetition and irrelevance, I will repeat my short history with vitality impairment and mortality.  I began by trying to find out what kills fish. The word fish applies to all animal types in a fishery. We chose to do this in the lab for control reasons, given the common confounding of stressors in fisheries (Davis 2002). All sorts of objections were made by field people that the work was irrelevant because it did not include field conditions. Well we focused on the fish and their capabilities, in an effort to formulate hypotheses that could be tested in the field. We found that each species and size of fish has different sensitivities to stressors and that stressors of importance were different for species.  We also found that some stressors (temperature and hypoxia) could kill fish without apparent macro-injury. After killing many fish, we endeavored to identify characteristics (traits) of fish and fisheries that could be correlated with mortality as predictors, given the difficulty of holding fish and measuring delayed mortality in the field. We tried many traits; muscle and plasma physiology, stressors, volitional behavior, injury, and reflex actions.

Effects of fishing gear, temperature, and fish size on sablefish mortality, NOAA.

Muscle and plasma physiology were not correlated with mortality because these are alarm responses that can be adaptive or maladaptive responses to stressors. In specific contexts, lactate and CO2 may be useful where hypoxia or fatigue are a concern.  

Stressors are an approach that has garnered enthusiasm. However their effects can be confounded and difficult to model given the relatively unlimited combinations of factors that are possible in a fishery; seasonal effects, gear type and deployment times, catch type and amount, sorting and discarding.  

Volitional behavior is not correlated with mortality because it is subject to variation that is not directly linked to mortality, such as changes in perception, motivation, fear, and attraction; all which confound the relationship of behavior and mortality.  

Injury is often correlated with mortality, especially in accidental death.  However not all mortality is correlated with injury, as in the effects of temperature and hypoxia, for which micro-injury may be evident (apoptosis) but difficult to measure in the field. Often the effects of injury, temperature, and hypoxia are confounded making interpretations of their effects on mortality difficult.

Single reflex actions are often not correlated with mortality when they are part of systems not central to body function and regulation directly related to mortality. They may be important for complex behaviors; predator avoidance, feeding, habitat choice, migration and these can have indirect effects on mortality. 

We reasoned that fish had a quality called vitality and that vitality was correlated with mortality. However, for an individual fish this relationship is binomial. The fish is alive or dead. So decreasing vitality results in sublethal effects on behavior until a threshold is reached and the probability for death increases rapidly. In statistical groups of fish, decreasing vitality is log-linearly related to mortality.

At this point we chose to not measure the strength of reflex actions (because of confounded size effects); instead to score the presence or absence of several reflex actions as an expression of reflex action impairment and loss of vitality. Reflex actions are fixed behavior patterns based on neural, muscle, and organ functions which do not vary with changes in perception, motivation, fear, and attraction.  We chose to focus on several types of reflex actions to increase the probability that reflex actions key to body regulation were included. Later work has shown that the orientation reflex is such a key reflex, often correlated with morbidity and mortality associated with hypoxia and fatigue. 

Previous work with vitality scoring in fisheries had developed the semi-quantitative analysis method (SQA) of scoring fish activity and injury, which was used in tagging studies and in Pacific halibut discard mortality estimation (ICES 2014). The method observes the sequential loss of operculum clamping and startle to touch and increased injuries from minor to major and bleeding; with ordinal scoring (1-4) for severity of impairment. The vitality score is readily incorporated in multivariate models that may identify stressors of importance to mortality and model mortality based on those stressors. RAMP can be scored in a similar manner as SQA and included in multivariate models. RAMP scores severity of impairment by noting the sequential loss of several types of reflex action and inclusion of injury types. Scores range from 0 to a maximum which is the number of trait types observed for presence/absence. Strength of action and extent of injury are not included because of the confounding effects of size. The effect of size is included in the model explicitly as fish length or weight. Smaller fish will have more vitality impairment than larger fish, when exposed to equivalent stressors.

RAMP is a simple extension of the SQA concept that includes more testing for reflex actions. SQA and RAMP are similar scoring systems that differ by emphasis. SQA and RAMP score activity, responsiveness, and injury to quantify levels of vitality impairment. RAMP simply includes more information about types of reflex actions in an effort to include reflex actions that are central to body regulation over a range of stressor conditions.

The primary reason for inclusion of more reflex action information in RAMP is the observation that some reflex actions are central expressions for status of body regulation. Given the binomial nature of mortality observations, we need to know why fish die. They die for many reasons which all seem to point to the loss of physiological regulation; either homeostatic or allostatic regulation. How do we measure regulation?  Allostasis shows us that consideration of homeostatic set points is not sufficient to predict mortality. My view is that vitality is correlated with physiological regulation and that impairment of vitality and regulation leads to mortality when physiological bounds of the species are exceeded. Until we can directly measure the causes for mortality, we rely on measures for vitality based on activity, responsiveness, and injury.

For predicting mortality, I chose to measure vitality over modeling stressors because of the direct relationship between vitality impairment and mortality. Stressor interactions in fisheries can make interpretation of stressor effects on mortality difficult to interpret. Information about stressors in multivariate models for mortality can be used to identify changes in the design of fishing gears that reduce bycatch mortality. Then vitality impairment can be used to evaluate reduction in discard mortality associated with new gears.

Human delayed mortality can be predicted using olfactory impairment

Olfactory impairment in humans was measured by error rate in olfaction tests. Increasing number of errors in olfaction tests were related to increasing 5-year mortality rates in a logistic regression (PLoS ONE). 

The human logistic relationship between olfactory impairment and 5-year delayed mortality is a powerful method for predicting delayed mortality and is similar to other animal RAMP relationships between reflex impairment, injury, and delayed mortality. Olfactory impairment can be easily measured in human and animal clinical settings and can easily and automatically be measured in aquaculture contexts by analysis of animal distributions and activity in rearing facilities. Given the fundamental nature of olfaction, one would expect the relationship between olfactory impairment and delayed mortality to be generally present among animal phyla and this can be tested in clinical and field settings.

Pinto et al. 2014 state, “We are the first to show that olfactory dysfunction is a strong predictor of 5-year mortality in a nationally representative sample of older adults. Olfactory dysfunction was an independent risk factor for death, stronger than several common causes of death, such as heart failure, lung disease and cancer, indicating that this evolutionarily ancient special sense may signal a key mechanism that affects human longevity. This effect is large enough to identify those at a higher risk of death even after taking account of other factors, yielding a 2.4 fold increase in the average probability of death among those already at high risk (Figure 3B). Even among those near the median risk, anosmia increases the average probability of death from 0.09 (for normal smellers) to 0.25. Thus, from a clinical point of view, assessment of olfactory function would enhance existing tools and strategies to identify those patients at high risk of mortality.”

(PLoS ONE)

The human study controlled for the mortality effects of age, gender, socioeconomic status, and race. Additionally, “We excluded several possibilities that might have explained these striking results. Adjusting for nutrition had little impact on the relationship between olfactory dysfunction and death. Similarly, accounting for cognition and neurodegenerative disease and frailty also failed to mediate the observed effects. Mental health, smoking, and alcohol abuse also did not explain our findings. Risk factors for olfactory loss (male gender, lower socioeconomic status, BMI) were included in our analyses, and though they replicated prior work [41], did not affect our results.” Note that the study did not control for effects of possible episodic exposure to toxins or injury that may result in temporary or permanent olfactory impairment not related to death.

Olfactory response is an involuntary response to a stimulus, and may be considered a reflex action. In the human study, presence or absence of smell detection for rose, leather, orange, fish, and peppermint were summed and related to delayed mortality. Olfactory responses to various substances can be scored as present or absent and summed to predict delayed mortality. In the same way, the RAMP method is an example of presence-absence scoring with summation of reflex impairment and injury scores to predict delayed mortality.  Measuring and summing whole animal responses, i.e., olfaction, reflex actions, and injury to stimuli is a powerful method for observing the effects of stressors and aging on delayed mortality.   

“We believe olfaction is the canary in the coal mine of human health, not that its decline directly causes death. Olfactory dysfunction is a harbinger of either fundamental mechanisms of aging, environmental exposure, or interactions between the two. Unique among the senses, the olfactory system depends on stem cell turnover, and thus may serve as an indicator of deterioration in age-related regenerative capacity more broadly or as a marker of physiologic repair function [13].”

Clearly, measurement and summation of presence-absence for whole animal involuntary characteristics (olfaction, reflex actions, and injury) is a powerful way to predict delayed mortality in humans and other animals.

Making and Using RAMP in Fisheries

A video is available that explains making and using RAMP in fisheries.

Why is vitality impairment related to mortality?

By definition, healthy animals have full vitality. Vitality becomes impaired as animals become stressed by capture and handling. Severe vitality impairment can result from the effects of physical injury or other stressors, e.g., fatigue, temperature, light, sea state, and air exposure. Maladaptive stress responses or critical injury associated with severe vitality impairment can result in immediate and delayed mortality.

Why score reflex actions and injury?

Reflex actions are fixed behavior patterns that are directly related to vitality impairment, without control by volitional behavior factors, e.g., motivation, hunger, fear, shelter seeking, migration, and reproduction. Reflex actions reflect the state of neural, muscle, and organ functions.

Injuries are directly related to vitality impairment because they can control neural, muscle, and organ functions.

Scoring vitality impairment in general

Any type of reflex action or injury that is related to vitality can be summed to score vitality impairment. The important point is that a sum of presence/ absence scores for vitality characteristics produces an index of vitality impairment. This vitality index can then be used as a measure of variability for sublethal stressor effects in fisheries, as well as a validated indicator and predictor of mortality and survival.

Steps for making and using RAMP in fisheries.

Assumptions for use of RAMP

Loggerhead sea turtle escaping trawl, NOAA

Here is a list of key assumptions for the use of RAMP. The list is probably not exhaustive and can be added to as new perspectives and research warrant. These assumptions have been experimentally tested and validated to various degrees by peer-reviewed published research. Further validation is useful and helps to better define possible error terms in RAMP curves. Healthy, control animals are assumed to have a full complement of reflex actions present. See choices for reflex action testing. 

Vitality is inversely related to reflex impairment. Animal vitality is an abstract concept for which we have strong intuitive notions related to observing absence of injury and presence of behavior, including activity and responsiveness. Reflex actions are fixed response patterns to stimuli that clearly reflect internal state without confounding factors. By using reflex actions to quantitatively measure vitality, the confounding effects of volitional behavior and motivation that are often more related to external conditions can be eliminated. Also animals may not be injured, yet show reflex impairment and reduced vitality associated with other factors (e.g., temperature, exhaustion, hypoxia, and xenobiotics).

Reflex impairment is directly related to stressor types and intensities.  Stressors have been shown to induce reflex impairment, interpreted as symptoms of stress. Therefore reflex impairment is a useful measure of stress. Reflex impairment integrates the effects of stress in whole animal responses that are ecologically meaningful for vitality and fitness outcomes. An impaired animal can have morbidity or decreased predator avoidance, feeding, sheltering, migrating, and reproducing.

Reflex impairment occurs immediately after exposure to stressors. Time course studies for several species have shown immediate impairment after exposure to stressors.  Animals with lower levels of stress can then recover full reflex actions hours to days after exposure to stressors. Reflex actions are sensitive measures of sublethal acute and chronic stress as well as predictors of delayed mortality.    

RAMP curve is different for each species and related to stressor sensitivity. Each species has reflex responses that are evolved for habitat types in which they occur. Differences in reflex types and responsiveness among species are apparent in body types, predator avoidance, habitat choices, and feeding strategies. Some species are easily injured and reflex impaired, while others resist injury or are relatively insensitive to environmental insults (e.g., temperature, hypoxia, and hydrostatic pressure).

RAMP curve used for a species is experimentally derived by inclusion of appropriate types of stressors and animal sizes, ages, and sex. RAMP curves must be derived from reflex impairment observed in animals experimentally exposed to combinations of stressors present in systems of interest. Also animals representing size, age, and sex of interest should be included in impairment experiments. The experiments should result in animals with reflex impairment that ranges from 0 to 100%, with accompanying mortality. The curve must include the complete range of impairment and mortality to avoid extrapolation beyond available data. 

RAMP curve is stable for a species and comprehensive experimentally tested conditions. The stable RAMP curve, with defined conditions of reflex types and testing, can be used among widely different situations for measuring animal vitality, survival, and delayed mortality. Exceptions have been noted for larvae or juveniles with ontogenetically delayed development of reflex actions and spawning anadromous adults which show altered sensitivity to stressors.

Reflex actions in RAMP are given equal weighting rather than weighted differently. Reflex impairment used in a RAMP curve is the result of summing several reflex actions. This approach views the whole animal as the important entity of vitality and fitness. Different reflex actions may be affected by different stressor types. In stressor systems of interest, there are relatively unlimited sets of stressor combinations. Therefore, no a priori expectations of importance for specific reflex actions are made and all measured reflex actions can be equally important. However, the order of reflex action impairment relative to stressor intensity can give valuable information about species sensitivity and associated life history characteristics. 

Observers are assumed to objectively score presence or absence of reflex action in a replicable manner. This assumption is satisfied by using the “rule of doubt”. If any doubt exists about the presence of a reflex action, the action is scored as absent. If the reflex action is present without a doubt, it is scored as present. Further controlled comparisons of reflex scoring among observers is warranted to better define possible observer error terms.

RAMP mortality and survival predictions are dependent on the accuracy of captive holding, tagging, and biotelemetry experiments. To calculate RAMP curves, animals are observed for delayed mortality after initial exposure to experimental stressors. Mortality observed with captive holding is simply related to initial stress, assuming that holding conditions are not stressful.  Mortality observed with tagging or biotelemetry includes sources other than initial stress (e.g., additional stressors, predation, disease, and food limitation)(Thorsteinsson 2002).

Sedna, mother of all sea creatures, K. Sagiatok

Reflex impairment in dogs, birds, and turtles

Reflex impairment in animals treated by veterinarians (dogs, cats, birds, rabbits, and livestock) is widely tested as part of a neurological examination to determine the potential presence and location of neurological impairment. The neurological exam consists of tests on mentation, posture and gait, cranial nerves, proprioception, spinal reflexes, and sensory pain perception.  Detailed summaries of these test procedures can be found here and here. In the veterinarian context, results of these neurological exams are generally confined to determination of whether the nervous system is affected in a disease process and to provide an accurate anatomic diagnosis when the nervous system is affected.  Consideration of contributions to disease by neurologic, medical, and orthopedic sources are differentiated into separate testing protocols for the purpose of formulating diagnosis and treatment plans. 

 Clippinger et al. 2007

Vernau et al. 2007

The veterinarian sequence of neurological testing in dogs and cats has been applied to sea turtles.  Results of the study showed that many of the neurological methods for dogs and cats can be adapted for use in sea turtles. The authors concluded that a standardized neurologic examination resulted in an accurate assessment of neurologic function in impaired sea turtles and could help in evaluating effects of rehabilitation efforts and suitability for return to their natural environment. Another study made a detailed assessment of chelonian health that included measuring reflex impairment as part of emergency and critical care. Measured reflex actions included head lift, cloacal or tail touch, eye touch, and nose touch.

Freshwater turtles have been tested for reflex impairment in an effort to evaluate the effects of submergence and increased temperature in bycatch mortality of three species.

Stoot et al. 2013

The RAMP results from reflex impairment testing in fish and invertebrates suggest that the neurological and reflex state of an animal includes the effects of injury and infection when related to fitness outcomes such as recovery, vitality, morbidity, and potential mortality. This inclusion of fitness effects probably results from the fact that the RAMP method is a scoring system that expresses the proportion of whole animal impairment, calculated based on the presence or absence of a suite of reflex actions.  Shifting focus and perspective from individual mechanistic explanations for disease to comprehensive whole animal measures for vitality can help link reflex impairment with fitness outcomes.

Further study and reflection on human and veterinarian medicine approaches to neurological testing can probably inform selection of reflexes to be used in the RAMP approach for reflex testing.  The interaction of medical and RAMP perspectives for quantifying disease states may result in advances towards understanding how nervous system and reflex function can be a comprehensive indicator of disease and vitality states, combining the effects of injury, infection, and nerve impairment.

RAMP: from intuition to science

Lets begin with fish, but the discussion applies to all other animals that have reflex actions.  Every fisher, commercial or recreational, intuitively knows and expresses opinions about the vitality of their fish, either in the water or caught. Excitedly proclaiming fish on and then proceeding to catch the fish, admire its size, and then release, sell, or eat the fish. These intuitive observations are grounded in our sense of vitality that is an expression of activity and responsiveness.

Intuitive notions are great for telling fish stories and are notoriously fallible when the size or fight of the fish in question is described to other bystanders. But these notions can lead to a quantitative expression of animal vitality that is grounded in solid, repeatable, and predictive science. How do we do this?

Vitality can be an expression of activity, which is diminished in stressed, lethargic fish.  Stress is an adaptive response to stressors. When fish are stressed too much or for too long, they can become diseased or die, states that do not support healthy populations and species diversity. So this loss of vitality that we intuitively observe can have profound consequences. To understand and ameliorate these consequences, we need good quantitative science.

For the purposes of describing and quantifying animal vitality and its inverse, mortality, we can start with animals in good condition and health that have a full suite of reflex actions and then study how stressors impair reflex actions until the end point of death. We use the presence or absence of reflex actions because these are fixed involuntary actions that are directly related to vitality and not subject to the effects of animal size and voluntary, complex behaviors such as feeding, social interactions, predator-prey interactions, migration, and sex, which can be modified by temperature, light, food availability, motivation, avoidance, and attraction.

We use a calculated quantitative index of reflex impairment, RAMP, that combines the presence-absence scoring of several reflex actions. RAMP is an integrative index that communicates the vitality of a whole animal. Similar reflex-based indices are used in human medicine to evaluate general health, neurological condition, and potential outcomes for coma and other non-communicating patients, as well as for triage of emergency patients.

Identifying appropriate reflex actions is where the imagination expands. We have got to figure out how to "tickle" the animal. What stimuli make it respond in the fixed involuntary patterns we call reflexes? Appropriate stimuli and testing modalities depend on the size of the animal and the logistical constraints of the situation. There are many human examples for inspiration.

Lets look at reflex actions through a continuum of animal size and activity for examples.  This list is by no means complete. Reflex actions can be tested in fish larvae by observing free swimming animal startle, orientation, and avoidance in response to light, sound, food scent, and touching with a probe.  For juveniles, fish can be restrained and tested for body flex upon restraint where fish attempt to escape when restrained, dorsal fin erection in which the fins become erect when fish are restrained, operculum and mouth closure where the operculum or mouth clamps shut when lifted or opened, the gag response where the fish opens its mouth and flexes the body when the throat is stimulated and the vestibular–ocular response (VOR) shown by eye rolls when the body is rotated around the long axis. For free swimming fish, studied reflexes included orientation where the fish should normally be upright, righting reflex where the fish returns to an upright position and the startle response in which the fish shows rapid forward motion in response to stimuli. Adult fish can present special problems because of their strength and other approaches for free swimming fish are described in another post. Sharks and other dangerous toothy or spiny animals especially need imaginative approaches to testing reflex actions.

Once a suite of reflex actions can be consistently observed and easily quantified, then building a RAMP curve can be accomplished and quantification of reflex impairment, vitality, and prediction of mortality is made possible. The RAMP method and curves developed then allow for the systematic investigation of the effects of stressors and stress in animals and systems of chosen interest. RAMP results can be compared and contrasted with concurrent results from physiological and physical injury studies in an effort to synthesize multivariate solutions to a continuum of important basic and applied questions. These questions may include understanding reflex biology, stress biology, fisheries management, bycatch reduction, animal health, population dynamics, aquaculture practices, migration biology, reproductive biology, and conservation biology to mention a few. 

Why does RAMP work?

RAMP is a whole animal quantitative measure of health and vitality. It integrates several reflex actions that are combinations of neural and muscle function which are immediately responsive to the effects of stressors.  When an animal is exposed to stressors and becomes stressed, various physiological, organ, and behavioral systems respond in adaptive ways to compensate for the disturbance of stress. Initially these stress responses are beneficial, helping the animal avoid stressful situations and stimulating metabolism to support these adaptations. However if stress is prolonged, the animal begins to exhibit metabolic deficits and its health and vitality degrade.

An animal with disturbed states and degraded vitality can quickly become sick, moribund, and eventually die if stress persists at high enough levels. Prediction of animal death or recovery from stress requires measuring whole animal stress disturbances. Measuring disturbances of separate systems that make up the animal does not predict vitality and mortality because the whole animal is what dies, not the separate systems.

RAMP is a combination of several reflex actions that is an ideal predictor of whole animal vitality and mortality because it integrates the immediate effects of stress for the whole animal into involuntary fixed patterns of response that vary only with the vitality of the animal. If voluntary behavior is used as a predictor, other factors not related to animal vitality can control responses, making prediction of vitality difficult.  For example feeding and other social interactions can be controlled by motivation, resource availability, avoidance, and attraction. If component metabolic and organ systems are used as a measure, these do not reflect the whole animal vitality state because they exhibit peak responses to stressor intensities that are not related to stress levels in the whole animal.