WHAT BONE MARROW ABNORMALITIES MAY MEAN

Although bone marrow abnormalities of the cannon bone may appear alarming on diagnostic images, many are not associated with lameness, according to a new study from France.

Researchers at the University of Lyon reviewed the records of 166 sport and pleasure horses who underwent a standing magnetic resonance imaging (MRI) examination between 2009 and 2016. Based on clinical exams, the horses were divided into three groups: horses lame in the foot, horses lame in the fetlock and horses who were not lame. Next, an independent clinician examined the MRI images and classified the horses based on the presence and severity of lesions seen at the lower (distal) end of the cannon bone, at the level of the fetlock joint. The researchers found such lesions in 76.5 percent of the study horses.

When the information from the clinical exams and MRI analyses were compared, the researchers could find no correlation between the presence or severity of the bone marrow lesions and the

STUDY: EQUINE SKIN HOSTS MANY MICROBES

degree of lameness in individual horses. Nor was the severity of bone marrow abnormalities associated with any particular type or level of activity.

The group calls for further study to determine the clinical significance, if any, of bone marrow lesions of the distal end of the cannon bone, visible on MRI in horses.

Reference: “Bone marrow lesions of the distal condyles of the third metacarpal bone are common and not always related to lameness in sports and pleasure horses,” Veterinary Radiology & Ultrasound, November 2018

High-tech analysis has revealed that a horse’s skin, like his gut, is home to varied but stable bacterial communities, a finding that may have implications for wound-treatment decisions.

Working at the University of Montreal, the researchers used DNA sequencing to identify bacteria in wounds on equine limbs and flanks during various stages of healing. This advanced technology enables researchers to identify organisms that might otherwise escape detection, according to Marcio Costa

DVM, PhD, and Christine Theoret, DVM, PhD, DACVS. “Only between 5 to 20 percent of bacteria can grow on traditional culturing media,” says Costa. “Therefore, they remained unknown for a long time. [With DNA sequencing], we now have a better picture of a bacterial community.”

For the study, identical surgical wounds were created on the lower front legs and a flank of four horses. On each horse, one leg wound was bandaged and the other was left uncovered, as was the flank wound. The dressing on the bandaged wounds was changed every two to three days. Researchers took biopsies of all wounds after one, two and three weeks of healing. No systemic or topical medications were administered during the study period.

The data showed that each individual’s skin had unique microbiota profiles, but there was some consistency in the types of bacteria found at particular wound locations on all of the horses. For instance, bacteria from the genera Fusobacterium and Actinobacillus were more abundant in limb wounds than in wounds on the flanks. The reason for this isn’t clear, says Costa, but differing bacterial populations could have practical consequences: “Fusobacterium, for example, has been associated with skin ulcers in humans and digital dermatitis in cattle, so its presence on equine limbs might also make healing more difficult.”

The researchers also found that unbandaged wounds harbored a greater variety of microorganisms than did bandaged wounds. “I cannot say whether this is good or bad,” says Costa, “but in general, diversity is associated with a healthier community.”

He adds that all four of the bandaged limbs developed exuberant granulation tissue (proud flesh) but, given the small sample size, this doesn’t necessarily mean that bandaging contributed to the problem. “Maybe in the future we can use this information for other research,” he says, “for example, to develop a probiotic that is proven to improve healing---you can bandage the wound with this ‘medication.’”

In each study horse, the microorganism profile of healed wounds was similar to the profile found on the intact skin samples collected from healthy control horses. This, the researchers say, is a sign of the stability and resilience of microbiota communities on equine skin.

Reference: “Use of next generation sequencing to investigate the microbiota of experimentally induced wounds and the effect of bandaging in horses,” PLOS One, November 2018

The variety and stability of the bacteria living on a horse’s skin may have implications for wound treatment.