- Written by: Sharalee Worms
MH stands for Malignant Hyperthermia - it is a dominant disease 
Genetic Testing is Available
MH causes severe tying up and possible death in affected horses after exposure to certain types of anesthesia. (if you have an MH horse you must make sire your vet knows about it before performing any surgery involving an anesthetic) Other symptoms include high temperature, erratic and heavy sweating, a rapid heart rate, irregular breathing and rigid muscles - these are often brought on by stress from exercise, excitement, trailering, change of ownership, etc Emergency cases of MH can be treated with dantrolene.
MH affects Quarter horses and related breeds and has been traced back to a mare named Miss Ogallala (98% of MH horses trace to her) - we are still searching for a couple other very rare lines of MH in Quarter horses.
*** If your horse has been diagnosed with MH please consider sending us the pedigree, especially if Miss Ogallla is not an ancestor.
*** If your horse has died under anesthetic please consider sending us the pedigree
- Written by: Sharalee Worms
Why Is It Important to know if your horse has genetic defects?
There are many reasons, here are just a few:
- Some health risks can kill your horse if not handled properly. eg If your horse would have PSSM and HYPP (quite common) the tried and true fix for a horse having an HYPP attack (Karo Syrup) can trigger a
PSSM attack that could be just as serious or even fatal.
- PSSM symptoms can easily, and have often been misdiagnosed as Colic, laminitus, and myriad of other expenisve to diagnose rmuscle injuries and many people have spent alot of money on vets only to come to the realization that a $40 test could have given them the answer they were looking for.
- Genetic testing can help you avoid problems later when purchasing a horse.
- Genetic testing can help you make good breeding decisions.
To learn more about specifc issues click the small arrow on the GENETIC ISSUES link in the main menu above.
We track all the issues listed on this site. If you see something missing that you would like us to track, please contact us.
- Written by: Sharalee Worms
AIS stands for Androgen Insensitivity Syndrome - it is a recessive defect which causes females to be sterile.
Mares will look and act like a stallion. Heavily muscled, aggressive to other mares in heat and displaying other typical stallion behaviours. These mares can be helped by gelding them. They look like mares in every way but they also have internal male testicles.
It has been documented in Quarter Horses, Throughbreds and Standardbreds,
If you have an AIS mare or suspect you have one we would be very interested in her pedigree - please consider contacting us.
- Written by: Sharalee Worms
CHF is Congenital Hepatic Fibrosis - a recessive disease
CHF affects the liver - foals are small for their age and have a potbelly.
There is no treatment and CHF foals are usually put down.
To date, it has only been found in the Franches-Montagnes breed (all affected horses in that breed trace back to the stallion Elu, born in 1964, and he is an ancestor on both the sires side and the dams side) and it was also found in one Spanish Purebred foal.
- Written by: Sharalee Worms
CSNB stands for Congenital Stationary Night Blindness - it is a recessive disease
CSNB causes an inability to see well in the dark - horses have it when they are born and it does not get worse as they get older.
It is assicated with the LP pattern gene so it affects Appaloosas - horses with LP/LP (few spot) are affected.