Topics of Discussion

CURRENT STEM CELL RESEARCH

Andy Hoffman, D.V.M., D.V.Sc., D.A.C.V.I.M., Professor, Director, Lung Stem Cell Laboratory and Jose Garcia-Lopez, DVM, DACVS, Associate Professor.

Understanding Stem Cell Potency: Can the Veterinary Profession Do Better?

Stem cells have now captivated the veterinary profession and for good reason.  These cells produce a vast array of molecules that promote repair and regeneration of damaged tissue. The signals produced by stem cells are so numerous and complex that they cannot yet be reproduced in the laboratory.  Harnessing their potential is the central focus for many laboratories around the world. The hope is that stem cells will revitalize tissue in healing wounds, and reduce inflammation, fibrosis, and auto-immunity. It’s a tall order but there is good evidence from animal models that stem cells or their derivatives can accomplish these goals.  Continue reading

Topics of Discussion

The Problem with Puncture Wounds

It is uncanny how some of the smallest, seemingly innocuous wounds can become the most life-threatening. Those located around synovial structures (joints, tendon sheaths and bursas) often fall into this category. Early recognition of synovial structure involvement followed by aggressive therapy wins the battle in many cases, but not all. The statistics are worse when recognition or therapy is delayed. Having owners who are caring but also knowledgeable about limb anatomy is an important first step. Owners are often the first responder – making the decision on whether to contact their veterinarian.  It is an easy decision to make when blood is spurting, flesh is hanging, or bone is visible but not so easy when the wound is a puncture or just an inch or so in length. Perhaps some of the following information will be helpful in highlighting the importance of small but badly placed wounds. Continue reading

Topics of Discussion

Septic Arthritis, Tenosynovitis, and Bursitis 

Infection of synovial structures may involve joints (septic arthritis), tendon sheaths (tenosynovitis) or a bursa (bursitis), which is a fluid-filled cavity situated within tissues exposed to friction. The infection occurs when microorganisms are given time to colonize the space after a penetrating wound, a joint injection, following surgery or following a spread of bacteria via the blood stream (hematogenous infection).  Although common in the foal, hematogenous spread is rare in the adult horse but has been reported to occur (< 10% of cases). Therefore, synovial infection should be considered as a potential differential diagnosis in any horse with sudden onset of lameness, synovial effusion (fluid buildup) and fever.  Horses with drainage through communicating wounds will generally be less lame than those without drainage.  Therefore, it is important to rule out possible synovial structure communication with a wound at the time of injury rather than wait to see if the horse becomes lame.  Many times, these horses do not become significantly lame until 7-10 days later when the overlying wound has closed sufficiently to prevent synovial drainage. Continue reading

Clinicians and Staff

Patricia Provost – VMD, MS, DACVS

Dr. Patricia Provost

Whether mentoring future veterinarians, treating sick or lame horses and other large animals, or performing research for the advancement of veterinary care, Dr. Patricia Provost joined Tufts to make a difference in the lives of animals. Dr. Provost is a board-certified surgeon (Diplomate of the American College of Veterinary Surgeons (ACVS) Continue reading

Clinical Case Review

The Case of a “Street Nail”

The contrast material fills the navicular bursa.

Nagel, a four year old Quarter Horse gelding, presented to the Tufts Hospital for Large Animals at the Cummings School of Veterinary Medicine after stepping on a nail, which entered the outer aspect of his right hind sole. Initial home treatments included daily foot soaks, phenylbutazone (an anti-inflammatory) and a course of antibiotics. Unfortunately, Nagel’s lameness returned despite his owner’s supportive and diligent home care. Radiographs taken by the referring veterinarian showed a penetrating wound that was tracking to the navicular bursa, with a small volume of gas observed within the bursa. Contrast injection into the site of nail puncture confirmed a communication of the wound with the navicular bursa. At that time, Nagel was referred to Tufts for exploratory arthroscopy. Continue reading

Innovation

Regional Limb Perfusion

Regional Limb Perfusion (RLP)

Regional limb perfusion (RLP) is a technique which provides a high concentration of an antibiotic to the soft tissues, joints, and bones of the limbs. The antibiotic used would be very expensive if given at a dose appropriate for the entire horse but the cost of the drug is more affordable since it is delivered into a superficial leg vein below the level of a tourniquet, and the benefits great. Drug concentrations achieved generally exceed that required to kill many types of bacteria and persist locally in the tissues for an extended period of time. This makes RLP a practical adjunctive treatment for septic conditions affecting the extremities (the knee and hock and below). Continue reading

Topics of Discussion

Environmental Management of IAD

IAD is an inflammatory condition of the airways that is triggered by exposure to a high level of particulates in the air, such as dust, mold, pollen and spores. Studies have shown that feeding – especially hay and pelleted feed – is the most important contributor to inhaled dust. Other important sources are cleaning stalls and sweeping the aisles. Exposure can be reduced by Continue reading

Topics of Discussion

What is Inflammatory Airway Disease [IAD]?

IAD is a disease of the airways which disturbs normal lung function (most often causing exercise intolerance) in addition to acting as a source of irritation (causing cough). Clinical signs are associated with swelling or obstruction and thus narrowing of the lower airways, which prevents air from reaching the maximum number of air sacs (alveoli) for gas exchange. In horses suffering from IAD, the airways are narrower because of inflammatory secretions, excessive mucus and fibrous tissue. In order to overcome the resulting increase in airway resistance, the horse has to work harder to achieve each breath and ultimately becomes exercise intolerant.

Horses with IAD most commonly present with a Continue reading

Clinicians and Staff

This Month’s Guest Editors

Dr. Melissa Mazan

Melissa Mazan, DVM, DACVIM

Dr. Melissa Mazan

Dr. Melissa Mazan, DVM, Diplomate ACVIM, is an Associate Professor and Director of the Equine Sports Medicine program at the Cummings School of Veterinary Medicine’s Hospital for Large Animals. Lung function, she notes, is essential to the success of equine athletes, and optimizing performance for competing horses is an important goal for hers. Dr. Mazan has extensive experience in the area of equine inflammatory airway disease, which affects as many as 80 percent of stabled horses and has provided pathways to better understanding similar human diseases, such as emphysema.

Dr. Daniela Bedenice
Dr. Daniela Bedenice

Daniela Bedenice, DVM, DACVIM, DACVECC

Dr. Bedenice, Dr. Med. Vet, Diplomate ACVIM, Diplomate ACVECC, joined the Tufts faculty following specialized training in large animal critical care and respiratory medicine. Dr. Bedenice became board certified in the specialty of large animal internal medicine in 2002, followed by large animal emergency and critical care in 2005. She works as an Assistant Professor in the Department of Clinical Sciences at Tufts, which combines teaching, research and a clinical referral service in the field of camelid and equine health care. Her special interests lie in comparative respiratory medicine, early disease identification and management, as well as newborn and adult intensive care. In collaboration with Drs. Hoffman and Mazan, Dr. Bedenice has been integrally involved in the characterization of lung disease, as well as development and validation of pulmonary function testing across species.

Dr. Andrew Hoffman
Dr. Andrew Hoffman

Andrew Hoffman, DVM, DVSc, DACVIM

An expert in equine lung function, Dr. Andrew Hoffman, DVM, DVSc, Diplomate ACVIM, is a Professor, researcher, and clinician at the Cummings School of Veterinary Medicine’s Hospital for Large Animals. Dr. Hoffman has spearheaded the development of non-invasive lung function testing of animals at the Cummings School, including Continue reading

Innovation

Techniques of non-invasive Lung Function Testing

In the clinical setting, three main non-invasive methods are currently used at Tufts to  test lung function in awake large animals: Forced Oscillation Techniques (FOT), plethysmography and measurement of functional residual capacity (FRC), which is an estimate of lung elasticity.

Forced oscillation techniques (FOT) are non-invasive tests to measure the resistance of the breathing system and thus evaluate airway narrowing. Different frequencies (1-7 Hz) of small air-pulses are directed into the patient’s airways via a face mask, while a computer captures changes in pressure and flow of these waves during spontaneous breathing. This calculates respiratory system resistance (Rrs).

FOT Lung Function Testing

A horse with airway inflammation undergoing FOT lung function testing at Tufts' Hospital for Large Animals.

A high Rrs often indicates airway narrowing due to thickening of bronchial walls and / or mucous accumulation in the lower lung. In horses with lower airway inflammation (e.g. IAD), we commonly observe a frequency dependence of resistance. This means that higher values for resistance are recorded at the lower oscillatory frequencies (1-2 Hz), a finding that is indicative of bronchoconstriction. Higher oscillation frequencies (> 2 Hz) provide information concerning central airway resistance. Baseline respiratory resistance measurements using Forced Oscillation Techniques can also be combined with bronchoprovocation tests to determine airway hyperreactivity or “twitchiness.” Continue reading