The "Packaging" Method: It can compromise the rescue patient

Clinical management of recumbent (down) horses has improved in veterinary medicine over the past several decades. This can be attributed to collecting data in veterinary hospitals where recumbent horses are seen as part of emergency receiving and anesthesia procedures, which induces recumbency. We have learned much by measuring physiological parameters for respiration, tissue perfusion, muscle and nerve function, gastrointestinal, urinary tract, and nervous system involvement. It is well documented that complications may arise from the primary disease or develop secondarily from being down. Horses have evolved to spend most of their lives standing, and healthy horses tolerate brief periods of recumbency sleep. Many factors determine how quickly a recumbent horse develops secondary problems. These include what happened to produce the recumbency, environmental aspects of what the recumbent horse is laying on, the degree of struggle, the body weight and muscle mass of the horse, and even genetics (PSSM) and, importantly, the time duration of recumbency. Regarding the latter, horses being anesthetized and placed in lateral recumbency on soft padded tables, provided ventilation, IV fluids, and temperature control can develop some degree of muscle, nerve, and other complications often within 2 hours. 

With that very brief background, we turn to the equine rescue patient who is found to be recumbent in various circumstances. In some situations, to remove the horse from these adverse circumstances, there are times when the rescue team has used a skid under the equine patient and secured the horse tightly to the skid in what has been termed the 'packaging method.' A valid question becomes: 

What are the concerns for a compromised, or sedated or anesthetized horse having front or rear legs tucked up under the horse on a hard surface and having straps cinched tight across the chest and mid body- the 'packaging' procedure? 

To answer this question, Dr. John Madigan* sought the input of Dr. Robert Brosnan, a board-certified anesthesiologist and veterinary medical teaching hospital faculty who has anesthetized thousands of horses and participated in emergency patient care of referred horses arriving at the hospital recumbent. Horses that are 'packaged' have their front legs pulled up under them, their rear legs pulled forward and compressed onto the skid, and cinch straps are ratcheted across the horse, including the chest, to secure the horse to the skid. Dr. Brosnan offered some insight, which I have summarized here:

Three issues to be considered for this procedure: 

What is the risk of myopathy and neuropathy - which will be a function of the duration that the horse is confined because 1) for the front legs, you can't take pressure off the triceps or the radial nerve, and 2) for the back legs, there is a risk of compression of the femoral nerve and rear limb muscle strain. These concerns are made worse if it is a bigger horse or a horse that is cardiovascularly compromised from dehydration or if hypoxemia is present from compromised ventilation, both of which increase the risk of muscle injury (myopathy). Poor positioning increases the risk of neuropathy. 

Another concern is, under anesthesia or heavy sedation, how well do these horses ventilate in this position?  Our research shows horses with some degree of mid-body compression from the Anderson sling, when heavily sedated, do not ventilate adequately and need mechanical ventilation to lower their CO2 and maintain normal blood oxygen levels. Awake animals can produce an extra effort to breathe when some degree of chest and abdomen pressure is present, but a heavily sedated or anesthetized horse won't have that same ability. Horses in this packaging with straps, as described, may be at risk of having poor ventilation that could deprive tissues of oxygen.

The last concern is if the horse starts to emerge from sedation or anesthesia, the magnitude of struggling could produce what we call capture myopathy, which is very difficult to recover from. 

Take home points:

1. The time factor for horses becoming compromised from being recumbent would start before any rescue team arrival, and the duration of recumbency should be determined at the start of each rescue attempt to determine how best to rescue the horse and not produce further trauma or debilitation. Does the patient require IV fluid resuscitation, pain control, limb stabilization, etc, before beginning any rescue attempt? The longer a horse has been down and will be down as part of the rescue procedures will further lessen the chance of recovery.

 2. The packaging procedure may further compromise respiration and could increase the risk of muscle and nerve injury from the legs being pulled into in the secured position on the skid.  

 3. If the rescue requires the use of the packaging procedure for extraction, it should be used for as short a time as possible, and when it is no longer essential to the rescue, the packaging should be removed. 

 4. Pulling a down horse packaged on a skid into a horse trailer and then transporting the horse should be discouraged as it exacerbates the adverse effects of recumbency. 

We hope this brief feedback to the question about packaging is useful. There is much more information for the veterinary aspects of approaching the down equine patient. Look for CE we are preparing to share with our dedicated first responders and veterinarians responding to these low-frequency, high-hazard incidents. By working together and emphasizing the safety of the first responders as well as optimal veterinary medical care and procedures for the rescue patient, we have the best chance of success. 

*About the author- Dr. John Madigan is a distinguished professor emeritus at UC Davis and founder of the UC Davis veterinary emergency response team. He is board-certified in both internal medicine and animal welfare. He has developed and evaluated equine sling systems and developed protocols for helicopter-assisted equine rescue and approach to the down horse. He has 40 years of experience in equine emergency care and multiagency equine incident response. He is currently CEO of Loopsrescue LLC (Loopsrescue.com). 

Copyright John Madigan, Loops Rescue.com- permission to duplicate approved for veterinary and animal rescue groups when used with reference and without alteration. jemadigan@gmail.com