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Other Names: Cranial Trauma
Head trauma is fairly common in chickens, occurring in multiple presentations and severity, from mild to life-threatening. Head injuries may be outwardly apparent by the presence of hemorrhaging, loss of tissue, and in many incidences, complete exposure of the brain. In other cases, birds may not show any external evidence of a head injury, but will present with a wide range of temporary to permanent clinical signs of neurological impairment. The later case is most commonly seen in crested-head chicken breeds (such as the Silkie, Polish, Crevecoeur, etc.) that possess a vaulted skull (an open void or hole on the top portion of the skull). This makes these chicks, highly susceptible to brain trauma, as there is nothing more than skin and feathers protecting the brain tissue. Sometimes all it takes is one hard peck the head by a flock member or accidentally bumping their head in the right way. Any trauma to the brain can cause neurological signs and/or sudden death. As chicks grow, sometimes the voided area will eventually seal itself shut or at least reduce in size.
Case 1: Traumatic brain injury in a White-crowned pionus A 13-year-old female white-crowned pionus was examined because of seizures 22 months after it was treated for a traumatic brain injury (TBI) characterized by vision loss, hemiparesis, nystagmus, circling, and head tilt. Bloodwork performed during the initial seizure workup revealed hypercalcemia and hypercholesterolemia, which were attributed to vitellogenesis given the bird's previous egg-laying history and recent onset of reproductive behavior. Magnetic resonance imaging of the brain revealed diffuse right pallium atrophy with multifocal hydrocephalus ex vacuo, which were believed to be the result of the previous TBI. Findings were most consistent with post-traumatic seizures (PTS). Levetiracetam (100 mg/kg [45 mg/lb], PO, q 12 h) was initiated for PTS management. A 4.7-mg deslorelin implant was injected SC to suppress reproductive behavior. The bird was reexamined for presumed status epilepticus 5 times over 22 months. Seizure episodes coincided with onset of reproductive behavior. The levetiracetam dosage was increased (150 mg/kg [68 mg/lb], PO, q 8 h), and zonisamide (20 mg/kg [9.1 mg/lb], PO, q 12 h) was added to the treatment regimen. Additional deslorelin implants were administered every 2 to 6 months to suppress reproductive behavior. The owner was trained to administer midazolam intranasally or IM as needed at home. The treatment regimen helped control but did not eliminate seizure activity. The bird was euthanized 22 months after PTS diagnosis for reasons unrelated to the TBI or PTS. Long-term management of PTS in a pionus was achieved with levetiracetam and zonisamide administration. Ref
Case 2: Beak deformity in a Cockatoo A 5-month-old bare-eyed cockatoo presented for the inability to eat because of a mandibular prognathic condition. The bird was being maintained through hand feeding formula three times per day. The bird was evaluated for corrective surgery based on the previously stated criteria and was determined to be a good candidate. On the day of surgery the bird was administered Normasol subcutaneously at 3% BWT, intramuscularly butorphanol 0.5 mg/kg and intramuscularly midazolam 0.5mg/kg 30 minutes preoperatively for hydration, analgesia and sedation. Anaesthesia was induced with ketamine 30 mg/kg intramuscularly with two subsequent doses of ketamine 15 mg/kg as needed for effective anaesthesia throughout the 60 minute procedure. The first step is to prepare the rhinotheca surface by grinding off the extra keratin layers using a carbide dental burr to achieve a uniform smooth surface. The beak is cleaned with water and dried. The rhinotheca is shortened to remove some of the curvature in the tip. This assists in the creation of a new bite plane in the prosthesis for the tomium to rest on. The next step is to increase the bonding surface area of the rhinotheca for the prosthetic attachment. This is necessary for the longevity of the composite bond. The Profin directional system uses multi-grooved files with depths of 0.2 to 0.5 mm for this purpose. The file is positioned on the rhinothecal surface perpendicular to the growth axis of the rhinotheca and grooves are created over the entire intended bonding area of the rhinotheca. The amount of retention can be tailored based on the file selected. The 0.2 mm file increases the bonding surface area by 13% and the 0.5 mm file increases the bonding surface area by 29%.The beak is cleaned again to remove all the keratin debris from the grooves. For placement of the two dental posts, a position is located on each side of the rhinotheca to minimize post-surgical pain and achieve maximum retention. The rhinothecal occlusal surface is identified at the caudal edge of the ventral rhinothecal file-like surface. A perpendicular line is traced dorsally from this edge to locate the junction where the lateral rhinothecal wall overlaps the ventral (occlusal) rhinothecal surface. The vascular dermis is located dorsal to this location. The ideal drilling point for the dental post placement is just ventral to this vascular layer in the centre of the rhinothecal occlusal surface. The drill is advanced 1-2 mm into the centre of the occlusal surface. If the vascular dermis is inadvertently penetrated minimal damage will occur to the maxilla bone at this depth and location. The holes are tapped (threaded) using a full length dental post that had been previously sterilized. These posts are removed and pre-cut dental posts with 3mm length tips are inserted leaving the dental post heads at least 1 mm above the rhinothecal surface for retention of the composite material. Any remaining beak surface debris is removed. The light cure bonding agent is applied to the three rhinothecal surfaces and cured. There is a primer that only works on dentin but helps clean the keratin surface and prepares it for the bonding agent. It is applied with a brush and light cured for 20 seconds. The bonding agent is then applied over the primer and light cured for 10 seconds. The triad composite material is moulded over the rhinotheca to shape the prosthesis similar to the expected normal upper bill conformation, but extended a distance beyond the tomium to ensure the bird was incapable of recreating the prognathic condition. This is tested by opening and closing the bill and manipulating the mandibles through their range of motion. The goal is to achieve intimate contact of the composite material with the rhinothecal surface and fully encompass each dental post into the prosthetic device. The composite material becomes softer as it heats up so it should be kept in the refrigerator until it is used in the procedure. Direct hand contact with the composite material can also alter its curing properties. Wearing latex gloves during the procedure and retaining the outer cellophane layer integral to the composite sheet material minimizes this risk. Once the appropriate shape and orientation is achieved, the prosthesis is cured for 10 seconds to stop any further conformational change. Full curing was achieved with multiple 20 second curing intervals covering the entire surface area of the composite prosthesis. The composite cellophane layer is then removed. The shaping of the prosthesis should be accomplished before the curing stage of the composite material. If minor alterations are needed, the cured composite can be modified using various dental carbide burrs designed for this purpose. Avoid contact of the aerosolized cured composite debris with the eyes, nasal or oral cavities of the bird or the surgeon. The surgeon should wear a mask and eye guards and cover the eyes and nares of the patient to prevent any possible reaction. Wetting the prosthesis before preforming any post cured alterations will minimize aerosolisation of the prepolymerised fillers. After completion of the surgical procedure, the surface of the prosthesis is cleaned with water and dried to remove the remaining cured composite residue. The patient recovery is very gradual utilizing this anaesthetic protocol. The patient is restrained in a towel and placed in a dark cage to be monitored. Eating after the patient fully recovered occurredquickly with the offering of soft foods. The patient was returned home with no maintenance of the prosthesis required. The prosthesis was rechecked every 3 weeks to evaluate the rhinothecal growth and the quality of the bond. In this case the rhinothecal growth altered the location of the ideal bite plane. Additional composite material was bonded to the prosthetic’s ventral surface to re-establish the ideal bite plane and occlusal forces. The rhinotheca continued to grow, the composite bonds broke, and the prosthesis sloughed 77 days post surgically leaving the remaining hyperkeratinized surface of the rhinotheca. The rhinothecal surface was shaped and contoured using dental burrs to achieve the final resolution of the mandibular prognathic condition. This bird has continues to eat normally and has maintained a normal rhinothecal-gnathothecal articulation for over three years. Ref