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Online survey generatio

To evaluate genetic predisposition, symptoms, and environmental (feeding, exercise, handling) factors, generatio is running a large-scale scientific survey, gathering data on horses that have been tested for the MIM (“PSSM2”) variants.  Owners who have tested their horses are invited to complete the survey of 174 questions. 

To the study & survey


With a sufficient number of completed responses, statistical analyses will be performed to identify correlations between different variants/variant combinations, symptoms, responses to management changes, etc.  This will form the basis for a scientific publication based on large-scale testing data. Note that for most questions regarding symptoms, management, etc., multiple answers are allowed.

Highlights from preliminary data (06.03.2023; 1590 completed surveys)

This is not an overview of all horses tested by generatio to date, only those who have completed the survey. It is expected that this may skew towards affected animals, since those owners may be more motivated to answer the survey.


When filling out the survey, all owners gave explicit permission for this data to be used for the scientific purposes of this study, and all identifying information was anonymized prior to data aggregation and analysis. All “routine work” data (results, animal tested, customer, etc.) are kept strictly confidential.


Of the horses for which we have survey results, 179 (11%) horses were n/n for all tested MIM/”PSSM2”variants; all others (89%) were positive for at least one of the tested MIM/”PSSM2” variants.


Sex: 46% mares, 52% geldings, 2% stallions

Primary use of horse: Recreational: 76%, Sport: 24% (55% retired from sport, 45% active)

Age at testing: The majority of horses tested (70.3%) were between the ages of 5 and 13 years


Laboratory testing: 69% of horses had bloodwork done

  • 17% had increased AST, 27% had increased CK, 38% had increased LDH


Reason for testing: 87% of horses were tested because of being symptomatic

  • 53% had their first symptoms noted between the ages of 4 and 7 years

  • 30% had been tested for other genetic mutations involved with Exertional Myopathy

    • PSSM1: 92% tested: 93% n/n, 7% were n/P1, 0% P1/P1

    • MYH1-myopathy (IMM): 17% tested: 86% n/n, 14% n/MYH1, 0% MYH1/MYH1

    • MH: 19% tested: 98% n/n, 2% n/MH, 0% MH/MH

Symptoms prior to testing

Behaviour: Pain-related behaviour changes (aggression, etc): 66%, Explosive behaviour: 55%, saddle shyness: 50%, difficulties with farrier: 54%


Movement: Reluctance to go forward: 71%, lameness: 42% (improving with movement: 62%), atactic gait, coordination problems/ropewalking: 37%, difficulties with collection: 70%, requiring extended warm-up phase: 76%; difficulties with gait changes: 54%; high muscle tension: 76%; typing up: 13%


Muscle: Difficulties with building muscle: 65%, muscle atrophy (hindquarters, topline): 48%, focal muscle atrophy: 41%


Other: Respiratory system abnormalities: 44%, increased sweating: 27%, increased symptoms in cold weather: 74%, leaning on walls/pseudonarcolepsy: 10%; stifle problems: 26%; kissing spines/ECVM: 10%, ulcers: 30%; diarrhea: 30%; dark or bloody urine: 9%

Feeding and management changes after receiving test results

Made Feeding changes: 91%

  • Increased: protein/amino acids: 86%; mineral supplement: 73%, magnesium: 71%, Vitamin E: 66%

  • Decreased: Oats: 39%; Alfalfa: 33%; Grain: 46%

  • Changes in Symptoms: Improvements: Behaviour: 82%, Muscle/Movement: 85%, majority within 4 weeks (especially - overall symptoms: 77%, stiffness: 70%, muscle softness: 64%, willingness to move forward: 59%)


Made Training/Exercise changes: 63%

  • Increased: warm-up time: 61%, routine training: 58%, daily movement: 44%

  • Changes in symptoms: Improvements: 80%, majority within 4 weeks (especially overall symptoms: 77%, behaviour: 82%, stiffness: 73%, muscle softness: 65%)


Most helpful changes in owner’s perspective: Feeding: 71%, expectations of horse: 40%, Training/Exercise: 40%

After testing and management/feeding changes

Horse can be used for original purpose: 47%; horse can be used but not as planned (sport, etc): 30%; not well managed: 8%; other: 15%

NOTE: This data shows only trends in preliminary data of some symptoms and management strategies. Because this is a survey of what owners have done and not a case-controlled study, it is not possible to differentiate between the impacts of different changes (feeding, training/exercise, etc.).


Muscle Integrity Myopathy (MIM, “PSSM2”) variants are not listed in this summary because over 2500 completed surveys are necessary to be able to calculate associations/correlations with statistical significance.