Case Report: Adult Female Bald Eagle

Winner, Abstracts and Cases
Chelsea Anderson, Cornell University

Signalment: Adult Bald Eagle, Female

 

Common problems: Bald eagles do not commonly present to the Wildlife Health Center but most cases have been fractures secondary to trauma or lead toxicity.

 

History and clinical presentation:

This Bald Eagle presented to the Wildlife Health Center on 02/05/2011 after being brought in by a rehabilitator. The eagle was seen walking sternally with its wings folded, down an embankment and across a two-lane road into a bush. Upon presentation the eagle was quiet, alert and responsive and sternally recumbent. On initial evaluation of the legs, the bird was not moving and seemed to have no deep pain when stimulated by hemostats. The cloaca did not have any tone when palpated with forceps. When pressure was applied to the right metatarsal region, the bird reacted appropriately by flapping her wings and moving away from the stimulus. A small wound was seen near the uropygial gland but otherwise the integument was normal. The left leg was slightly abducted away from the body. A small amount of blood was seen in her mouth and on inspection was coagulated in the oral cavity, with a few drops in her glottis. She was weighed at 5.55 kg.

 

Presenting problems:

• Pelvic fracture (left most significant)

• Paraparesis

• Inability to urinate/defecate voluntarily (spinal trauma)

 

Triage plan

• Subcutaneous fluids (Plasmalyte 30ml/kg) were administered to combat dehydration and promote cardiovascular stability.

• Manual expression of the cloaca BID-TID

• Put in sling for 5-6 hours to alleviate respiratory signs and aid digestion.

• Enrofloxacin (15 mg/kg SQ SID): administered to treat infections of many gram-negative and some gram-positive organisms. This antibiotic is concentration-dependent and does not treat for anaerobic organisms; Bactericidal- inhibits DNA-gyrase preventing DNA supercoiling and DNA synthesis.

• Butorphanol (1mg/kg IM BID): a partial opiate agonist/antagonist used as an analgesic in birds. The action of butorphanol is thought to occur primarily at kappa and sigma receptors, which is effective for birds because they have a majority of kappa receptors. This analgesic is more effective in birds than morphine which targets mu receptors. All opiates should be used with caution in patients with hypothyroidism, renal insufficiency, and adrenocortical insufficiency.

• Meloxicam (1 mg/kg SQ SID): non-steroidal anti-inflammatory drug (NSAID) administered to reduce inflammation, pain and pyrexia through its inhibition of cyclooxygenase, phospholipase A2, and inhibition of prostaglandin synthesis. Meloxicam is considered COX-2 preferential and should be used with care in a dehydrated animal due to the possibility of increased renal toxicity. It is administered IM because due to the first-pass effect with oral administration, only about 1/6th of the administered dose reaches the systemic circulation. 

• Vitamin K (2 mg/kg IM once): given to alleviate a potential coagulopathy, possibly due to warfarin poisoning in this case.

• Vitamin E (40 IU/kg IM once): commonly given as an antioxidant especially if feeding fish to the patient.

• Vitamin B Complex (10 mg/kg SQ in fluids SID): given to stimulate appetite and to replenish thiamin since we were feeding some frozen fish which contain a higher concentration of thiaminase.

Diagnostic plan:

Complete blood count (CBC) and chemistry panel to determine overall health by observation of red and white blood cell morphology and relative counts, and the extent of inflammation.

Radiographs (V/D and lateral) to reveal any fractures (possibly pelvic) or internal injuries the eagle may have acquired.

 

The results of these tests provide initial evaluation of the eagle’s status. In addition, they provide a data point for monitoring the animal over time. Blood work should be rechecked after treatment has had time to take effect to monitor for improvement or if no apparent improvement is observed. Radiographs should be repeated to check for bony callus formation that indicates proper healing of the fracture site. In birds, callus formation is expected after about 5 weeks, but a prolonged healing time is expected in open and contaminated fractures.

 

Results for in-house point of care bloodwork showed a PCV of 36%, TS = 4.0 g/L, and glucose was high. Laboratory bloodwork showed PCV 53%, TS 2.8 g/dL, WBC 22,600, AST 116, and CK 2851. Blood gas showed a pH of 7.516 with a possible metabolic alkalosis and respiratory compensation (pCO2 = 26.6 mmHg), however the sO2 was only 88%. This bird had been sternally recumbent and is a heavy bird. Respiration may have been compromised.

Radiographs revealed a large distracted fracture just proximal to the left coxofemoral joint. There may be other pelvic fractures, but were difficult to see. The cardio-hepatic outline was large, and the hepatic margins were enlarged. A small mammal was visualized in the ventriculus and crop due to a recent meal. The air sacs were compressed, most likely due to an enlarged gastrointestinal tract (recent meal and decreased voiding). 

Monitoring:

(02/06/11) The eagle was maintained on the treatment plan described above except that the Vitamin K and Vitamin E were  only given once at the time of presentation. The cloaca was manually expressed and white urates with some hint of green (possibly feces) was seen. She was weighed at 5.65 kg (up 100 grams from the day before). She was set up in a sling to aid respiration and digestion for a few hours and then propped up with towels for the night.

(02/07/11) The following morning she was quiet, alert and responsive and she was offered fish. She had not moved from her towel all night. She did not pass feces or urates on her own but with stimulation mostly urates were passed. No casts were seen as well. She did react to hemostats applied to her feet- she moved her talons and withdrew her legs. The cloaca may have had some improved tone. No more oral bleeding was noticed, and no other areas of hemorrhage were seen. The eagle was weighed at 5.70 kg (up 50 grams from the day before). She was treated again with subcutaneous fluids, butorphanol, meloxicam, and enrofloxacin. She was put in the sling for a few hours again and then moved to the towels for the night.

(02/08/11) The bird was brighter this morning, was seen weight bearing in an attempt to stand mostly on her right leg. She had turned around to face the door during the night. She was put in a sling all morning and girpped the perch under the sling well. Her crop was palpated as empty (full on presentation), as was her caudal coelom but no casts or feces were seen. Her inability to voluntarily urinate and defecate for a 4-day duration may be indicative of spinal trauma. She weighed in at 5.60 kg (down 100 grams from the day before). All her medications remained the same, except oral fluids and metoclopramide were added. Metaclopramide is used to stimulate upper gastrointestinal motility without stimulating gastric, pancreatic or biliary secretions. It appears to sensitize upper GI smooth muscle to the effects of acetylcholine. It is contraindicated in patients with gastric hemorrhage, obstruction, or perforation. Better imaging of the pelvis is necessary (possibly CT?) but if the nerve deficits remain, euthanasia will be an option.

(02/09/11) The eagle was quiet, alert and responsive. She was offered fish. She is passing urates on her own now. Copious amounts of loose and bright green feces were seen. No cast was seen. She was sternally recumbent but did make an attempt to stand (right leg stronger than left). She weighted 5.40 kg (down 150 grams since admission). She was extremely dyspneic this morning, open mouth breathing even before handling. When she was restrained for treatments she was given flow oxygen. Blood was taken to recheck her CBC, chem, blood lead, blood zinc, cholinesterase, and an Aspergillus panel was sent to Miami. She was put in her sling all morning and still gripped the perch well. She did seem uncomfortable after a few hours and was therefore removed from the sling and remained sternally recumbent for the rest of the afternoon. A large amount of loose, green feces was expressed from the cloaca. It seems that the urates are being passively passed but feces are collecting. She resented palpation of the caudal coelom and reacted strongly. There was dried blood on the roof of the mouth, choanal slit and down into the esophagus. The blood was removed somewhat with cotton tipped applicators. All treatments remained the same except that the metroclopramide was discontinued and itraconazole (10 mg/kg PO BID) was initiated. Itraconazole is a synthetic oral antifungal that alters ergosterol synthesis in the cellular membranes of susceptible fungi thereby increasing membrane permeability and allowing leakage of cellular contents. It is used for systemic mycoses including aspergillosis, and superficial candidiasis or dermatophytosis. 

Overall the eagle showed mild improvement in leg strength and movement but was never able to stand. She showed rapid deterioration systemically as she became dyspneic, tachypneic, and began to regurgitate foul smelling dark green blood-tinged material. The blood clots and mucus noted in her mouth on presentation continued to form in spite of daily cleaning suggesting this material was either regurgitated or coughed up. The second hematology and biochemistry profile was relatively unchanged from the time of presentation except that the PCV was 25%, WBC 18,300 with 1,500 bands, and TS = 3.5 g/dL.

(02/10/11) The following morning the eagle was noted to be open mouth breathing and was sedated with butorphanol and midazolam for placement of an air sac cannula due to progressive dyspnea. Midazolam is a benzodiazepine used primarily as a premedicant for general anesthesia. A potential adverse effect would be respiratory depression. A routine approach for placement of the air sac cannula into the left caudal thoracic air sac was made. This involves going caudal to the last rib and ventral to the flexor cruris medialis muscle. There was difficulty in determining if the endotracheal tube inserted into the air sac was placed properly as no air was detected moving in or out. However, when hemostats were advanced through the incision, clinical impression was that the placement was correct. This raised concern that the air sac itself was obstructed or not ventilated due to some other lung pathology. An endoscopic exam of the upper airway did not show any obstruction. Radiographs were repeated and revealed almost complete obliteration of the lung fields and air sacs. Additionally, the heart and liver were displaced. Due to these findings, the orthopedic abnormalities, the advanced lung pathology, and the great distress the bird was in while awake, it was decided to euthanize her while she was under anesthesia. 

 

References:

Plumb, Donald C. Plumb’s Veterinary Drug Handbook, 6th Edition.  PharmaVet Inc. Stockholm, Wisconsin. 2008.

 

Stauber, E, N Finch, PA Talcott, and JM Gay. 2010. Lead Poisoning of Bald (Haliaeetus leucocephalus) and Golden (Aquila chrysaetos) Eagles in the US Inland Pacific Northwest Region—An 18-year Retrospective Study: 1991-2008. Journal of Avian Medicine and Surgery. 24(4): 279-287.

 

Redig PT, DR Smith, and L Cruz-Martinez. 2009. Potential sources of lead exposure for Bald Eagles: A retrospective study. Extended abstract in R.T. Watson, M. Fuller, M. Pokras, and W.G. Hunt (Eds). Ingestion of Lead from Spent Ammunition: Implicatinos for Wildlife and Humans. The Peregrine Fund. Boise, Idaho, USA.