Scoring systems and scales have been developed in veterinary medicine to provide a structured framework for assessing and monitoring patients across different domains. We have scales to assess and monitor physical conditioning (e.g., Body Condition Score (BCS), Muscle Condition Score (MCS)), pain (e.g., feline grimace scale, Glasgow Composite Pain Scale), critical care illness (e.g., Systemic Inflammatory Response Syndrome, Animal Trauma Triage), specific diseases (e.g., Canine Inflammatory Bowel Disease Activity Index), and quality of life. These scoring systems, as well as others, help to reduce subjectivity and cognitive bias in our assessment of patients, standardize serial examination criteria, and improve the quality of our documentation of findings over time and between examining clinicians.
When a dog or cat presents with head trauma, acute neurologic deterioration, or altered mentation, rapid and structured assessment is critical. Two validated scoring systems commonly used in veterinary medicine to assess illness severity include the Modified Glasgow Coma Scale (MGCS) and the Animal Trauma Triage (ATT) score. Both scales can improve triage decision-making, guide communications about prognosis, and objectively monitor trends over time. While they overlap in their assessment of consciousness and neurologic function, they do serve slightly different purposes.
The Modified Glasgow Coma Scale (MGCS) - adapted from the human Glasgow Coma Scale - examines three categories to assess severity of head trauma in veterinary patients. Each category is scored from 1 to 6 (1 = severely abnormal; 6 = normal):
Motor Activity (Score 1–6)
- 6 – Normal gait and spinal reflexes
- 5 – Hemiparesis, tetraparesis, or decerebrate rigidity
- 4 – Recumbent, intermittent extensor rigidity
- 3 – Recumbent, constant extensor rigidity
- 2 – Recumbent, constant extensor rigidity with opisthotonus
- 1 – Recumbent, hypotonia, depressed or absent spinal reflexes
Brainstem Reflexes (Score 1–6)
- 6 – Normal PLR and oculocephalic reflexes
- 5 – Slow PLR; normal to reduced oculocephalic reflexes
- 4 – Bilateral unresponsive miosis; reduced oculocephalic reflexes
- 3 – Pinpoint pupils; reduced to absent oculocephalic reflexes
- 2 – Unilateral unresponsive mydriasis; reduced to absent oculocephalic reflexes
- 1 – Bilateral unresponsive mydriasis; reduced to absent oculocephalic reflexes
Level of Consciousness (Score 1–6)
- 6 – Occasional alertness; responsive to environment
- 5 – Depressed or delirious but capable of responding (possibly inappropriate)
- 4 – Semi-comatose; responsive to visual stimuli
- 3 – Semi-comatose; responsive to auditory stimuli
- 2 – Semi-comatose; responsive only to repeated noxious stimuli
- 1 – Comatose; unresponsive to repeated noxious stimuli
A patient’s total score can range from 3 to 18.
- 15–18 → Mild brain injury / Good prognosis
- 9–14 → Moderate injury / Guarded prognosis
- 3–8 → Severe injury / Grave prognosis
Scores of 8 or less are associated with a survival rate of 50% [1], and with each one-point increase in the score, there is a 2.06-fold increase in the probability of survival [2,3]
The MGCS is particularly useful for assessing neurologic status of patients - especially forebrain and brainstem function - following traumatic brain injury (TBI).
The Animal Trauma Triage (ATT) score is a broader assessment tool designed to evaluate overall trauma severity. This score examines 6 different parameters including neurologic status of the patient. The other parameters assessed include perfusion, cardiac, respiratory, eye / muscle / integument, and skeletal. A total patient score can range from 0 (normal) to 18 (severest level of trauma).
The ATT neurologic component is scored from 0–3:
(0) - Central: Conscious, alert to slightly dull, interested in surroundings
- Peripheral: Normal spinal reflexes, purposeful movement, nociception in all limbs
(1) - Central: Dull / depressed / withdrawn
- Peripheral: Abnormal spinal reflexes but purposeful movement and nociception intact in all limbs
(2) - Central: Unconscious but responds to noxious stimuli
- Peripheral:
- Absent purposeful movement with intact nociception in ≥2 limbs, or
- Nociception absent in 1 limb
- Decreased anal or tail tone
(3) - Central: Nonresponsive to all stimuli, refractory seizures
- Peripheral:
- Absent nociception in ≥2 limbs
- Absent tail or perianal nociception
Highter total ATT scores correlate with increased trauma severity, greater mortality risk, and need for aggressive intervention. A total ATT score of 9 has been associated with an estimated 50% probability of survival [4,5], and each additional point has been associated with a 15% higher risk of developing systemic inflammatory response syndrome (SIRS) in patients with vehicular trauma [6], as well as significantly higher odds of mortality (1.78 in cats and 2.07 in dogs) [7].
In the emergency setting, these tools are complementary. Both systems assess level of consciousness, response to stimuli, presence or absence of nociception and severity of neurologic compromise, but they differ in scope and granularity. The MGCS is brain-focused and emphasizes motor patterns, brainstem reflexes, and depth of consciousness — better suited for traumatic brain injury cases. ATT is trauma-focused. It integrates central and peripheral neurologic findings into a global trauma severity index. A patient with severe brainstem dysfunction but minimal systemic trauma may have a low MGCS but score moderately on the ATT. A polytrauma patient with spinal cord injury and hypoperfusion may have a high ATT score, even if MGCS is relatively preserved.
In trauma patients — especially those with suspected TBI — using both scales can elevate the quality of triage, monitoring, and clinical communication. But studies have also shown that they should be used as part of a comprehensive assessment and not as a sole prognostic indicator due to their high but imperfect predictive ability.[8] The physiological status of trauma patients can change rapidly and these illness severity scores are just one variable to consider.
Regarding their reliability, several studies have compared the two:
- In one study, the ATT score was highly accurate in predicting survival and correctly identified all non-survivors based on a score threshold.[8] In contrast, the MGCS score showed good but less consistent accuracy, as one non-survivor in that study scored in the normal range. Their ๏ฌndings support the use of the ATT score as a reliable tool for assessing injury severity and guiding treatment decisions.
- Another study found that the MGCS demonstrated good performance overall, but that performance improved when restricted to just head trauma patients. However, when assessment was restricted to patients with head injury, the ATT score still performed better than the MGCS.[9]
- Yet another recent study concluded that the MGCS score (as a surrogate for TBI) is not ideal and is not always consistent with the Animal Trauma Triage neurologic score or the presence of head injury. Dogs with an MGCS score <18 had a lower chance of survival (67.7%) compared with dogs with an MGCS score of 18 (97.8%). In that retrospective evaluation, they also found that age and size correlated with lower MGCS scores, with younger and smaller dogs more likely to have an MGCS score <18.[10]
References:
1. Prognostic value of mGCS in head trauma in dogs. J. Vet. Intern. Med. 2001;15:581–584. doi: 10.1111/j.1939-1676.2001.tb01594.x
2. Performance Evaluation and Validation of the ATT Score and mGCS in Injured Cats: A Vet Committee on Trauma Registry Study. J. Vet. Emerg. Crit. Care. 2019;29:478–483. doi: 10.1111/vec.12885
3. Retrospective Evaluation of Prognostic Indicators in Dogs with Head Trauma. J. Vet. Emerg. Crit. Care. 2015;25:631–639. doi: 10.1111/vec.12328
4. Severe Blunt Trauma in Dogs: 235 Cases. J. Vet. Emerg. Crit. Care 2009, 19(6): 588–602. doi: 10.1111/j.1476-4431.2009.00468.x
5. Review of gunshot injuries in cats and dogs and utility of a triage scoring system to predict short-term outcome: 37 cases (2003-2008). J. Am. Vet. Med. Assoc. 2014, 245:923–929. https://avmajournals.avma.org/view/journals/javma/245/8/javma.245.8.923.pdf
6. Clinicopathologic abnormalities associated with increased animal triage score in cats with bite wound injuries: 43 cases (1998-2009). J. Vet. Emerg. Crit. Care 2019, 29(3): 296–300. doi: 10.1111/vec.12831
7. Retrospective evaluation of prognostic indicators in dogs with head trauma: 72 cases (January-March 2011). J. Vet. Emerg. Crit. Care 2015, 25(5):631–639. doi: 10.1111/vec.12328
8. Prognostic performance of ATT and mGCS scores in dogs and cats with traumatic injury.
Veterinary Sciences, Nov 2025, 12(11):1081. doi: 10.3390/vetsci12111081
9. Performance evaluation and validation of the animal trauma triage score and modified Glasgow Coma Scale with suggested category adjustment in dogs: A VetCOT registry study. JVECC 2018; Vol 28(3):192-200. doi: 10.1111/vec.12717
10. Retrospective evaluation of the epidemiology of Modified Glasgow Coma Scale Score and head injury in dogs—An ACVECC-VetCOT Registry study (April 2017 to December 2021): 9607 cases. JVECC 15 Feb 2026. doi: 10.1111/vec.70094
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