neurologic | Horse Racing Free Tips

Sidewinder Gait Bears Startling Similarity To Its Namesake

Named for the venomous snake, older horses afflicted with sidewinder syndrome have hindquarters that list to one side when they walk. This condition can be challenging to diagnose as there isn't a lot of research available on the abnormality, says New Bolton Center's Dr. Amy Johnson. The movement is considered a syndrome because it is a symptom and not a disease in itself and has different potential causes.

Johnson sees sidewinder gait come on suddenly in horses that are in their late teens and older. The affected horse's hind legs move so significantly to the side that the horse travels on three tracks. If the horse is drifting to the left, the left hind foot will be away from the body and the right hind will be in line with the left front when walking.

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When standing still, the affected horse often weights one hind leg more than the other – often the one that is closest to the body. Some sidewinder horses will spin in a circle when they walk or lean against a wall or fence to support their weak side.

Some causes of sidewinder gait include EPM, arthritis, or fractures. It's important to complete tests to determine if the cause is neurologic or musculoskeletal. Some horses have an acute onset of the gait abnormality, but may recover and go back to normal; the gait may or may not return. If it does come back, the hind end doesn't always track to the same side as before. Johnson hypothesizes that these cases may be caused by degenerative, age-related changes that create intermittent muscle spasms. Weather may also play a role, as Johnson sees more sidewinder gait in colder months. She believes this may be caused by aggravated arthritis or horses that are slipping on bad footing.

Often the older horses that develop sidewinder gait are euthanized, and even in necropsies it isn't always apparent what caused the gait abnormality.

Prognosis for complete recovery is poor. Some horses improve with exercise, while others need stall rest to avoid exacerbating the condition. Steroid use can cause issues in older horses that are already prone to endocrine issues and laminitis.

EPM is the only disease associated with sidewinder gait that can be treated. For horses with an inconclusive reason for the abnormal gait, it's difficult to predict which will improve and whether improvement will be permanent.

‘Accident-Prone’ Horses May Merit Additional Examination

Though horse owners often joke that their horses seem to be looking for ways to injure themselves, is there a point where a horse may be more than simply “accident prone?” Dr. Amelia Munsterman, Associate Professor of Large Animal Surgery and Emergency Medicine at Michigan State University, tells EQUUS magazine there may be some additional reasons a horse may seem intent to harm himself, including soreness, lameness and neurologic issues.

The first step in determining whether there's an underlying problem is to have the horse thoroughly checked by a veterinarian, including a focused neurologic exam. This exam will put the horse through a variety of movements to see if he knows where his limbs and body are in space. A lameness exam is also helpful as a horse that is sore may alter his gait and the way he moves, causing him to run into things.

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One other thing the vet should check is the horse's vision. Limited sight in one or both eyes will cause difficulty for a horse trying to navigate his surroundings.

If all of these tests yield no concrete answers, the horse may simply be very curious; adding toys to his stall may keep him out of trouble, Munsterman says. Ensuring he is in a regular exercise program can assist with channeling his extra energy, and spacing out feedings can also help keep him busy and out of trouble.

EHV-1 Outbreak At California Show Grounds Sees Six Positives, One Death

On July 25, a 6-year-old Warmblood mare in Sonoma County, CA, tested positive for equine herpesvirus (EHV-1), according to reporting from the California Department of Food and Agriculture. The show horse had been stabled at the Sonoma Horse Park in Petaluma, Calif., prior to her positive test. Though the mare was vaccinated, she was euthanized after becoming recumbent and unable to rise.

Managers of the horse show the mare attended notified all attendees, asking them to take temperatures of horses that had attended the show twice daily and quarantine any horses returning from the show for at least seven days. On the show grounds, 19 horses from the affected mare's barn were removed and quarantined at their home farm; the 18 horses left at the home facility had temperatures taken twice daily and the farm implemented enhanced biosecurity measures.

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Six horses at the premises tested positive for EHV-1 and began displaying fever and/or limb edema. One horse, a 15-year-old Warmblood mare, began displaying neurologic symptoms and was moved to isolation at a veterinary hospital for care. A 5-year-old Warmblood gelding that was stabled at the horse show with the euthanized mare tested positive for EHV-1 on July 30 and was isolated at the index premises.

There were seven confirmed cases of EHV-1: two were non-neurologic EHV-1 cases at the showgrounds, a 5-year-old Warmblood gelding and a 14-year-old pony mare. one horse thus far has been euthanized.

Further Analysis Of March EHV-1 Outbreak Reveals New Variant Of The Disease

In March, eight horses housed at a Pennsylvania show barn were diagnosed with EHV-1 after having elevated temperatures but no other signs of illness. The cause of the outbreak has been found to be a new variant of the EHV-1 H752 genotype. The variant contains the same mutation as the EHV-1 outbreak in France.

EHV-1 can cause respiratory disease in young horses, early death in foals, abortions in mares and occasionally neurological disease. Neurologic issues are fairly uncommon, but can cause the death of the affected horse.

The 31 horses that lived at the affected barn were treated with valacyclovir, and ill horses also received flunixin meglumine and sodium heparin. The investigation team, led by Dr. Nicola Pusterla, believe that the early administration of valacyclovir may have prevented additional horses from falling ill with neurologic complications. Additionally, they note the lack of respiratory symptoms in these cases may be related to the recent administration of EHV vaccinations.

The distribution of the new genotype is not known.

Read the case report here.