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Avian practice tips and tricks (Proceedings)

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Aug 01, 2011

My goal is to retire with the highest possible number of patients that have lived through treatment. This results in conservative care in many cases. This is NOT the most lucrative way to practice. It is the easiest emotionally. Medically, I believe it is usually the most sound.

In this lecture we will discuss the reasons that birds seem to "die easily". We will also cover:
     1) General approach to hemorrhage,
     2) Approach to the moribund bird,
     3) Diagnostic and treatment options and timing in the clinical ill but currently stable bird,
     4) Iatrogenic causes of injury and death in avian patients, and
     5) Specific cases and the risk/benefit of different treatment options.

First, birds hide signs of illness until late in the disease process. This makes the likelihood of disease progression to a serious or critical state prior to presentation high.

Secondly, birds present a greater risk when undergoing diagnostics, medical and/or surgical treatment, than do mammals (Note that reptiles pose a much lesser risk of fatality than do mammals).

The reason for this hierarchy is that the metabolic rate in birds is extremely high (and therefore the oxygen demand is great) – far exceeding that of mammals. Reptile requirements are even lower than mammals. One study conducted on box turtles consisted of gradual removal of the entire blood volume over a 48-hour period, while being replaced with an equal volume of isotonic solution. None of the turtles died, although recovery of normal function required supportive care.

We don't have this luxury with birds. Avian blood pressure increases up to 300% with stress. In fact, the blood pressure and rapidity of exsanguination make it unlikely that a practitioner will ever be presented with a bird whose life will be saved by immediate application of pressure to a bleeding site. Birds with this severity of hemorrhage die within seconds to minutes and are rarely presented to the animal hospital.

Most birds that become significantly weak from blood loss, become that way due to repeated attempts at hemostasis. The application of direct pressure or styptic to a blood feather, toenail, or wound and the restraint that is used to apply this, create pain and fear, respectively. This increases the blood pressure; whatever clotting has begun is subsequently disturbed, and bleeding begins again. When this is repeated several times over several hours, hypovolemia and anemia occur.

Blood pressure, rate of blood loss and oxygen demand factors are increasingly significant as the size of the bird decreases.

Approach to the bleeding bird:
     1) If the bleeding has stopped - Don't look for the source, don't mess with the clot!!
     2) Discuss with the owner the need to minimize additional hemorrhage. The bird needs to be hospitalized for at least several hours, and possibly longer.
     3) Administer midazolam @ 0.5 mg/kg, IM. Let the bird sit in a quiet, warm area. Offer water (most will drink if blood loss has been significant). When the midazolam has quieted the bird, administer warm S.C. fluids.
     4) When no further bleeding has occurred for several hours, and you believe the blood volume has been replaced, administer midazolam again if it is no longer on-board, and locate the source of the bleeding (laceration, broken blood feather, area of mutilation, etc). Treatment then will depend on the condition of the bird, and the source of the hemorrhage. Often, no further treatment is required.