Genetic predisposition to chronic laminitis

Genetic predisposition to chronic laminitis

1994 AAEP CONVENTION Hoof length and limb kinematics Lengthening the hoof while maintaining the same hoof angle, palmar support, and weight significan...

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1994 AAEP CONVENTION Hoof length and limb kinematics Lengthening the hoof while maintaining the same hoof angle, palmar support, and weight significantly increased the maximum height of the toe in the arc of its flight during trotting. Maximum flexion of the metacarpophalangeal joint was found to be linked with maximum height of the tip of the shoe. The flight of the toe of the shoe was biphasic (double humped), with the m a x i m u m elevation occurring shortly after lift off. Other factors that may be modified by the farrier to enhance gait are: hoof angle, shoe weight, position of weight on the shoe, and whether weight is added to the fore or hind feet. Presented by Dr. Olin Balch

Genetic predisposition to chronic laminitis The relatively high prevalence of laminitis on certain farms or in specific blood lines of horses led to the clinical impression that a genetic basis for the disease might be present. Therefore, an evaluation of a herd of performance horses with a higher than normal prevalence of chronic laminitis was made. Affected horses in the herd were developing towards a mechanical collapse of the digit consistent with a physical, radiographic, and histologic diagnosis of chronic laminitis or founder. While the origins of this mechanical collapse were unclear, from a study of the pedigrees, it was obvious that these horses inherited the tendency to develop the


horses from the pedigree of the affected horses indicated a consistency with either an autosomal dominant or x-linked dominant pattern. Presented by Dr. D. M. Hood

Predicting lameness with navicular radiographs A retrospective study examined the medical records of 85 horses seen by one practitioner prior to purchase over a 7-year period showed no correlation between the incidence of radiographic changes and the development of lameness associated with the navicular bone within at least a 1-year period after examination. No clinical lameness was present in these horses. Radiographic navicular changes in these horses were graded on an open-ended navicular bone grading scale which ranges from 0 to 22. The mean score for the 170 navicular bones graded was about 8; but 32 bones graded from 15 to 22. The navicular bone can have a wide variety of changes from normal and still be apparently normal. Veterinarians in one study were apparently unable to distinguish between normal and abnormal navicular bones in radiographs of clinically normal horses and horses with clinically diagnosed navicular disease. Presented by Dr. David W. Ramey

Topical Metronidazole for equine canker Equine canker is a chronic hypertrophic, moist, eczematous pododermatitis that has a characteristic fetid odor. Historically, canker has most commonly been seen in the hind feet of draft breeds; however, in a more recent report, there was no predilection for

course of the disease it can be misdiagnosed as thrush. The cause of canker is unknown, although anaerobic gramnegative bacterial rods are consistently observed within the epithelium. Recommended treatments include keeping the foot clean, minor debridement, and antibiotic therapy in the form of both systemic and topical chloramphenicol. Because chloramphenicol is expensive and the human health risks are significant, metronidazole was used for treatment of eight cases at the University of Wisconsin, Madison. Each horse underwent a single debridement. The treatment period ranged from 2 weeks to 8 weeks, with a mean treatment period of 4.6 weeks. All cases resolved and the horses returned to their previous activities. Presented by Dr. David G. Wilson

Scintigraphy of the palmarplantar fetlock A retrospective study of 50 horses which had moderate to severe scintigraphic uptake in the palmar-plantar aspect of at least one of the distal third metacarpi or metatarsi was made. Clinical diagnosis of these horses included: stress remodeling (22); degenerative joint disease (5); osteochondral fragments or osteochondritis dissecans(4); sesamoiditis (2); incomplete condylar fractures (6); synovitis or capsulitis (4); traumatic chondrosis (2); P 1 chip fracture (3); and no diagnosis (2). The study indicated that the significant level of radiopharmaceutical uptake may be associated with more serious articular derangement than previously thought. Only 20% of the Standardbred horses in this study returned to an equal or higher level of performance after treatment, while 40% of the Thoroughbred