Treating avian patients with severe trauma (Proceedings)

It is a clinical challenge when veterinarians have to administer therapeutic procedures to pet avian patients.  The thoughtful use of therapeutic procedures on a debilitated patient is often correlated to the success or failure of treating a patient. 

The initial phase of evaluating a patient's health is through a rapid external physical examination.  If the patient appears to be severely debilitated or getting worse the bird should be “put down” and placed in a critical care unit.  Any antibiotic, chelation agent or fluid therapy should be initiated prior to the patient's placement into the incubator.

Fluid Therapy – this subject will be covered in detail in another presentation

Nutritional supplementation

Species specific or group specific diets have been formulated.  Examples of group or species specific diets are parrot, cockatiel, parakeet, canary/finch, lori and mynah/softbill.  Feeding group/species specific diets to breeding birds may increase clutch size, increase fertility of breeding birds, increase the number of clutches per year, provide better hatchability and healthier chicks that mature faster than birds fed lower quality diets.  With the advent of powdered hand feeding formulas, avian nutrition has arrived in the 21st century.  Homemade batch formulas no longer need to blended in order to adequately feed domestic raised companion bird species.  Hand feeding formulas are as easy to make as instant pancake mix – add warm water to the powder.  With the instructions on the box, the amount needed can be reconstituted without waste or storage.  All unused formula should be discarded to prevent bacterial contamination.  Also with warm water being used and the hand feeding formula being “ready to eat” the need to microwave the formula is no longer necessary.  By eliminating the microwave process the likelihood of young birds sustaining thermal crop injuries is drastically reduced.  There currently is debate on how often and when to feed young birds.  No matter how advanced avian nutrition becomes is still pales to properly fed parent raised birds.  If you look at birds being fed by parents the crop is always full.  This is completely opposite of the hand feeding techniques advocated by aviculturists and veterinarians over the last 25 years.  It is recommended that birds should be fed approximately 10cc/100 grams body weight when their crop empties.  Most hand feeding owners will come very close to following the rule of feeding on an empty crop.  We have noticed that certain bird species, in particular macaws, will often become stunted using this method of hand feeding.  There are specially formulated macaw formulas, and they should be used but also macaws seem to thrive when their crop is maintained full and allowed to empty overnight.  Hand fed birds should be weighed daily, in the morning when the crop is empty before the first feeding.  If the bird is not gaining weight the formula may contain too much water, is diluted with other ingredients, the bird is not fed often enough or is not getting enough food at each feeding.  Another problem with underdeveloped birds is that owners will “weaken” the formula to aid in digestion of a slow moving crop.  Weakening the formula only compounds disease problems a young bird may have by reducing the nutritional intake needed by the rapidly growing animal.  The needed nutrients are immense for a young bird and reducing the food intake by diluting the formula will have deleterious effects on the immune system. 

As important as fluid replacement, nutritional supplementation must be considered for the debilitated avian patient.1  To calculate the nutritional requirements for the avian patient, the following formula can be used:1

Calculate basal metabolic rate (BMR):

• BMR is K(W0.75)

• K = kilocalories (a constant) for 24 hours

• K = 78 for psittacines

• W = weight of the bird in kilograms

• Calculate maintenance:

• 1.5 X BMR

• Adjust maintenance requirements for stress (Table 1)

• Kcal required/day ÷ Kcal/ML formula = amount of formula in mL required per day

Adjustments to nutritional maintenance for stress (as multiples of maintenance energy requirements)

Starvation 0.5-0.7 Elective surgery 1-1.2 Mild trauma 1-1.2 Severe trauma 1.1-2 Growth 1.5-3 Sepsis 1.2-7.5 Burns 1.2-2 Head injuries 1-2

Birds that are extremely ill may need enteral feeding support.  There are products available through the Lafeber Company, Cornell, IL, that provides this critical care nutritional requirement.  Critical Care®, Nutri-Support® and Carbo-Boost® comprise the line up of the Lafeber avian critical care products. 

When treating the avian patient, environmental support has a significant impact on the success of many cases.  Environmental support can be classified as temperature/humidity control (in most cases heat), oxygen supplementation/administration and nebulization. There are many avian intensive care units (ICUs) on the market, but the veterinarian should carefully examine the clinic's needs before purchasing this piece of equipment.When comparing avian intensive care units, cheaper is not always better.1Important features that improve a unit's performance are digital temperature and humidity control, ease of cleaning /disinfecting and durability.

Air sac breathing tube

An air sac breathing tube is sometimes needed to regain an appropriate air flow into the lower respiratory system if the mouth, glottis or trachea is obstructed. An endotracheal tube (relative to the patient's size) is placed in the caudal thoracic air sac in the area of the last 3 or four ribs, just dorsal to the dorsal edge of the pectoral muscle.  The tube is placed through a stab incision that has been bluntly dissected through to the caudal thoracic air sac.  The tube is secured by inflating the cuff within the coelomic cavity (if the tube has a cuff) or suturing a tape butterfly, which has been applied to the tube, to the skin.  It has been the author's experience that to anesthetize or administer oxygen using an abdominal breathing tube requires a higher percentage of anesthetic agent plus an increased flow rate of oxygen.

Performing therapeutic techniques on pet avian species often means the difference in life and death.  Knowing the proper techniques and formulas required for avian patients using the proper equipment will result in treatment successes.

Products Needed for Wound Management

If one is to treat avian species, especially in potentially critical condition, it is important to have the proper equipment and products to improve the veterinarian's chances for treatment success.  Equipment starts out with a digital gram scale (Veterinary Specialty Products, Boca Raton, FL) that can measure up to 6 kg.  For smaller birds, a separate digital gram scale (Veterinary Specialty Products, Boca Raton, FL) measures up to 2 kg will be appropriate.  The primary difference between the scales is that the 6kg scale will likely weigh in 5 gram increments while the 2kg scale will have measurements in one gram increments.   For larger birds, dog and cat scales are used, while ratites need scales manufactured for large animals.  It is not only important to weigh the patient upon presentation to determine the proper therapeutic dosages, but to weigh the bird on a daily basis for patient response to treatment.  A temperature controlled critical care unit (Lyon Electric, Co, Inc., Chula Vista, CA) is also important .  This unit should be fitted for access to supplemental oxygen when needed for patients with respiratory distress. It is  desirable to have a unit with humidity control, as dry heat alone may result in dehydration of smaller patients, especially those with extensive wounds that contribute to fluid loss.  Many of the newer intensive care units have digital controls that are easy to  adjustment for precise  environmental parameters.. Isoflurane anesthesia is a must for any avian practice.  Sevoflurane (SevoFlo™, Abbott Labs, North Chicago, IL) is an anesthetic agent that has gained popularity in the last few years but the clinical benefit is negligible and the cost significantly more compared to isoflurane.

A pair of binocular loops (Surgitel®, General Scientific Corp., Ann Arbor, MI) and microsurgical instruments should be part of the avian practice.  Binocular loops and microsurgical instruments will be beneficial for any number of animal species undergoing surgical procedures at a veterinary hospital, including all avian patients.  The benefits of using binocular loops are numerous and only through their use will one truly appreciate the elevation of their surgical skills, especially with smaller patients.  Radiosurgical capabilities will allow the avian practitioner to use this state of the art technology from incision to closure.  Pathology is similar to the cold steel of a scalpel, and the dual frequency technology and digital programming of the radiosurgery (Ellman International Inc., Hewlett, NY) unit allows for cutting and coagulation, hemostasis and bi-polar forcep application.  There are many applications for  the radiosurgery unit in wound management, at a fraction of the cost of LASERs, without compromising surgical quality.  Adequate cage space is important for larger birds (e.g., cranes, egrets, ratites and raptors), while hydrotherapy tubs are required for waterfowl.

Therapeutic Agents for Bandaging

Therapeutic agents for the critical patient are often available in most hospitals and include catheters (1½” 22 gauge spinal needle for intraosseous catheters), crystalloid and colloidal fluids , iron dextran (Watson Labs. Inc., Corona, CA), oxygen-carrying hemoglobin solution (Oxyglobin®, Biopure®, Cambridge, MA) and a nutritional critical care formula  (Lafeber Co., Cornell, IL).  Analgesic compounds have been a beneficial addition to most veterinary hospitals and for the avian patient this has been no exception.  Meloxicam (Metacam®, Boehringer Ingelheim, St. Joseph, MO) and Carprofen (Rimadyl®, Pfizer Inc., New York, NY) and butorphenol tartrate (Torbugesic®, Fort Dodge Animal Health, Fort Dodge, IA) are two of the most commonly used analgesic compounds for avian patients.  The antibiotic, antifungal and antiparasitic agents used to treat both systemic and topical wounds are similar to those found in most veterinary hospitals.  Avian patients often tolerate oral fluid medications better than pill or tablet forms.  If a veterinary hospital does not have common antibiotic agents formulated in an oral suspension form, then a compounding pharmacy should be contacted.  Metronidazole hydrochloride (Watson Laboratories, Inc., Corona, CA) can be difficult to administer orally because of its poor taste.  Metronidazole benzoate is considered more palatable than the more common form manufactured in the United States. 

Topical therapeutic products, including antibiotic ointment may be applied depending on the nature of the injury and advantages of using the product for that particular case. When prescribing a topical ointment for avian use caution must always be taken into account.  Owners need to be educated on the application process, using only a small amount to treat the lesion to reduce the possibility of feather matting.  Topical ointments containing corticosteroids are not recommended for avian species due the high potential for severe side effects.  Preparation-H® (Wyeth Laboratories, Marietta PA) has been advocated for dermal wounds to decrease the healing time.  An active ingredient in the Preparation-H® ointment is live yeast cell derivative that increases the respiratory component of the epithelium surrounding the wound thereby increasing the healing capacity of the tissue.  There has been a recent advance in wound management with the advent of Tricide® (Molecular Therapeutics, LLC, Athens, GA).  This product is an antimicrobial potentiator used to flush the wound bed and control infection.  Some topical antibiotic preparations that have been used with success by the authors are triple antibiotic ointments (e.g., Neosporin®, Pfizer Inc, New York, NY) and silver sulfadiazine cream (SSD) (Smith & Nephew Heath Care, London).   

Bandage materials

Appropriate bandage material is extremely important in wound management.  Nonstick surface bandaging material (Adaptic®, Ethicon Inc., Arlington, TX) will protect the tissue bed and prevent leakage of serum into the contact layer and thereby prevent adhesion of the bandage to the wound.  Semiocclusive dressings (Tegaderm®) also aid in the healing of skin lesions but may be difficult to apply because of poor adhesive qualities.  Tissue glue (Nexaband®, Veterinary Products Laboratories, Phoenix, AZ) or cyanoacrylic bandages have been used to repair minor skin lacerations or incision sites.  Although tissue glue is convenient to use for the appropriate injury, it can be expensive and the shelf life has been disappointingly short.  Cyanoacrylic bandages have been advocated to cover larger tissue defects in the past, but there is a newer product that is more tissue friendly allowing for reepithelization and tissue respiration.  CARRASORB™ (Veterinary Products Laboratories, Phoenix, AZ) is another product that protects dermal lesions and speeds the healing process. CARRASORB™ is a freeze dried gel that is manufactured for application on medium exudating wounds.  It contains the ingredient acemannen, which is a complex carbohydrate product derived from the aloe vera plant, and can be applied topically to a dermal lesion that has been prepared similar to the manner described for VBS.  If the lesion is dry, then the freeze dried gel product may be moistened with a wound cleanser to provide a moist wound environment.

Items needed to complete bandages include cast padding, gauze sponges, VetWrap® (3M Company Animal Care Products, St. Paul, MN), Elasticon® (Johnson & Johnson Medical Inc., Arlington, TX) (and white cloth tape (waterproof and nonwaterproof.  Fiberglas cast material, temperature sensitive cast material (Vet-lite™, Runlite S.A., Micheroux, Belgium) and UV light sensitive dental acrylic (Triad™, Henry Schein, Port Arthur, NY) are used to make splints and wound bandages for the nonpsitticine avian species.  Ethylcyanoacrylates (ECA) (Cyanovanear™, Ellman International Inc., Hewlett, NY) using a catalyst is available for beak repair and UV light sensitive dental acrylic may be used for the same purpose.  Pins, wire and aluminum rods are used for beak structure foundations prior to the application of prosthesis and for foot braces respectively.

*The material contained in this proceedings article was previously published: Riggs SM, Tully TN: Wound management in nonpsittacine birds. Vet Clin N Am (Exotic Anim Pract) 7:19-34, 2004.

References

Tully TN. Psittacine therapeutics. Vet Clinic North America: Exotic Animal Prac. 3;1:59-90.

Greenacre CB: Comparison of sevoflurane to isoflurane in psittaciformes. Proc Assoc Avian Vet, Reno, NV, 1997, pp 123-124