Birds can suffer from a variety of neurological problems that affect their brain, spinal cord, and nerves. These conditions can be caused by infectious diseases, toxins, metabolic disorders, trauma, tumors, and congenital or inherited conditions. Some common neurological issues seen in pet birds include proventricular dilatation disease, heavy metal poisoning, vitamin deficiencies, trauma, strokes, and seizures. Identifying the underlying cause of neurological signs is important for determining treatment options and prognosis.
Infectious Diseases
A number of pathogenic bacteria, viruses, fungi, and parasites can infect the central nervous system of birds and cause neurological symptoms. Some examples include:
Viral Infections
– Paramyxovirus – Ferrets, minks, cormorants, pigeons, parrots. Causes neurological signs like tremors, seizures, paralysis. Highly contagious and often fatal.
– Eastern equine encephalitis (EEE) virus – Passerine birds, raptors, pheasants. Transmitted by mosquitoes. Causes inflammation of brain and spinal cord.
– West Nile virus – Crows, jays, hawks. Transmitted by mosquitoes. Can cause encephalitis, tremors, and paralysis.
– Avian influenza – Waterfowl, shorebirds. Some strains are fatal with neurological signs. Transmitted by feces and nasal secretions.
– Newcastle disease – Chickens, parrots, pigeons. Virulent strains cause tremors, drooping wings, twisting of head and neck. Highly contagious and fatal.
Bacterial Infections
– Chlamydiosis – Parrots, pigeons, songbirds. Causes inflammation of nerves, brain, eyes. Transmitted through nasal and eye secretions.
– Mycobacteriosis – Finches, parrots. Causes granulomas in brain, spinal cord. Transmitted through feces and secretions.
– Salmonellosis – Chickens, ducks, pet birds. Causes neurological signs like tremors, incoordination due to meningitis, encephalitis.
Fungal Infections
– Aspergillosis – Raptors, waterfowl, songbirds. Fungal granulomas form in brain, spinal cord, and nerves. Inhaled from environment.
– Cryptococcosis – Passerine birds and parrots. Yeast causes meningoencephalitis. Transmitted by inhalation.
Parasitic Infections
– Toxoplasmosis – Canaries, finches, parrots. Caused by Toxoplasma gondii. Forms cysts in brain causing encephalitis. Ingested from cat feces.
– Sarcocystis – Passerines, raptors. Protozoa forms cysts in muscles and neural tissue. Causes neurological deficits. Transmitted by ingestion of infected prey.
Toxicities
Exposure to certain metals, pesticides, organic toxins, and plants can have detrimental neurological effects in birds. Some examples include:
Heavy Metal Toxicity
– Lead – Major cause of toxicity in birds. Sources include lead paint, fishing weights, batteries. Causes blindness, seizures.
– Zinc – Ingestion of coins, galvanized metal. Causes pancreatitis, epilepsy, and paralysis.
– Mercury – From contaminated fish. Causes severe central nervous system damage and death.
Pesticides
– Organophosphates – Used in agriculture, home pest control. Inhibit cholinesterase causing overstimulation.
– Rodenticides – Anticoagulant rodenticides cause bleeding in brain. Seen in raptors consuming poisoned prey.
Organic Toxins
– Botulism – Produced by Clostridium bacteria. Causes flaccid paralysis, difficulty breathing. Associated with bird die-offs.
– Mycotoxins – Fungal toxins found in contaminated grain and food. Causes tremors, incoordination, paralysis.
Plants
– Lilies – All parts are toxic. Causes kidney failure and neurological signs in cats, also toxic to birds.
– Sago palm seeds – Extremely toxic, contain cycasin. Causes seizures, liver and brain damage.
Metabolic Disorders
Abnormalities in body metabolism can have neurological manifestations in birds. These include:
Hypoglycemia
– Low blood sugar can cause depression, seizures, coma. Seen with sepsis, liver disease, or anorexia in birds. Needs emergency treatment.
Calcium deficiency
– Hypocalcemia causes muscle tremors and seizures. Seen with poor diet or kidney disease. Correct with calcium supplementation.
Vitamin E deficiency
– Causes spinocerebellar degeneration, loss of balance and coordination. Supplementation can help support recovery.
Thiamine deficiency
– Lack of vitamin B1 causes neurological signs like seizures, paralysis. Seen with poor diet. Needs urgent thiamine injections.
Salt toxicity
– Excess salt causes weakness, tremors, seizures, head tilt. Provide fresh water and remove sources of salt/sodium.
Traumatic Injuries
Trauma to the head, spine or nerves can obviously lead to neurological impairments in birds. Some examples include:
Blunt Force Trauma
– Can cause concussions, hemorrhage, spinal and vertebral fractures. Seen with hitting windows, walls, cars.
Penetrating Trauma
– Lacerations, gunshot wounds. Cause bleeding, infection, nerve damage. Requires surgical treatment.
Neck Trauma
– Struggling against restraint can injure cervical spine and cause paralysis. Proper handling is important.
Burns
– Electrical or chemical burns can damage sensory nerves. Causes chronic pain, self-mutilation.
Bone Fractures
– Fractured ribs can damage spinal nerves. Leg fractures compress sciatic nerve causing paralysis.
Neoplasia
Tumors arising in the brain, spinal cord or nerves can impair neurological function in birds.
Primary Brain tumors
– Seen with glial cell tumors like astrocytomas, gliomas. Cause seizures, abnormal behavior, paralysis. Difficult to treat.
Secondary Metastases
– Myeloma, lymphosarcoma and other metastatic cancers spread to CNS. Impair function.
Peripheral Nerve Sheath Tumors
– Schwannomas arise from nerve sheaths. Cause pain, loss of function in that nerve. Surgical removal if possible.
Congenital Conditions
Some birds may be born with neurological abnormalities due to inherited genetic defects or developmental problems.
Wry Neck
– Abnormal twisting of neck. Caused by damage to bones/nerves in development. Non-treatable.
Polydactyly
– Extra toes can compress sciatic nerve. Causes lameness and paralysis. Toe amputation needed.
Hydrocephalus
– Fluid accumulation in brain. Causes domed skull, seizures. Caused by genetic defect. Progressive condition.
Micrencephaly
– Underdevelopment of brain. Occurs in utero. Causes severe mental impairment. Non-treatable.
Cerebellar Hypoplasia
– Underdevelopment of the cerebellum part of brain. Causes loss of coordination, balance. Congenital issue.
Diagnostic Tests
Various diagnostic tests can help determine the underlying cause in birds with neurological signs:
Physical & Neurological Exam
Assessing mentation, posture, gait, cranial nerves, spinal reflexes. Helps localize area of nervous system affected.
Complete Blood Count
Checks for inflammation and infection. Important to run with biochemistry panel.
Biochemistry Panel
Checks organ function, electrolytes, blood sugar. Important for metabolic issues.
Cytology
Microscopic examination of stained fluid or tissue samples. Can detect inflammation, infection, cancer cells.
Toxicology Testing
Screens blood, feces or tissues for known toxins like heavy metals, pesticides.
Diagnostic Imaging
– Radiographs detect fractures, masses compressing nerves/spinal cord.
– CT scan provides excellent 3D detail of brain anatomy and lesions.
– MRI shows soft tissue changes like inflammation and tumors affecting the nervous system.
Endoscopy
Allows visual examination of internal structures. Used to inspect proventriculus and air sacs.
Biopsies
Obtaining tissue samples for microscopic examination. Useful for identifying tumors, inflammation, and infection.
Necropsy
Post-mortem examination of organs and tissues. Can determine cause of death and sites affected by disease process.
Treatment Options
Treatment depends on the specific cause and may include:
Antibiotics
Used to treat bacterial infections causing neurological impairment. Choice depends on culture and sensitivity results.
Antifungals
Antifungal drugs like itraconazole prescribed for systemic mycoses affecting the nervous system.
Antiparasitics
Medications like fenbendazole to kill parasites in brain or spinal cord. Treatment course often needed.
Antiviral Drugs
Currently limited options for virus infections. Supportive care important.
Heavy Metal Chelation
Medications like dimercaptosuccinic acid (DMSA) bind and remove lead, zinc, mercury from body.
Fluid Therapy
Fluids and electrolytes administered for dehydration, metabolic issues, toxin exposure.
Nutritional Support
Correcting vitamin/mineral deficiencies. Tube or parenteral feeding if unable to eat.
Anti-inflammatories
Steroids and NSAIDs to reduce inflammation affecting CNS function. Short term use.
Anticonvulsants
Phenobarbital, diazepam for seizures. Chronic therapy often required for epilepsy.
Surgery
Mass removal, lesion debridement, nerve repair procedures. Can greatly improve function and prognosis if amenable to surgery.
Rehabilitation
Physical therapy exercises, hydrotherapy to improve strength and mobility if impaired. Requires owner commitment.
Prevention
Several measures can help prevent neurological dysfunction in pet birds:
Proper Husbandry
– Regular cleaning of enclosure, food/water containers
– Avoid overcrowding
– Stress reduction through environmental enrichment
– Proper day/night cycles, maintain comfortable temperature range
Balanced Diet
– Species appropriate formulated diet, with supplements if needed
– Provide clean, fresh drinking water at all times
– Variety of vegetables and fruits for micronutrients
– Remove spoiled, moldy food promptly
Routine Veterinary Care
– Annual wellness exams to monitor health
– Diagnostic testing for subclinical issues
– Quarantine and screening of new bird additions
– Prompt evaluation of any signs of illness
Reduce Toxins
– Avoid Teflon and other harmful fumes
– Use heavy metal free toys, bowls, perches
– Remove lead, zinc sources
– Use bird safe natural cleaning products
Safe Environment
– Avoid ceiling fans, open doors/windows
– Prevent access to toxins, poisonous plants
– Control rodents and insects which can transmit diseases
– Use microchip, leg bands for identification if escape
Prognosis
The prognosis depends on the specific condition causing the neurological signs. In general:
Good Prognosis
– Metabolic disorders if treated promptly
– Dietary deficiencies with supplementation
– Mild concussions or spinal trauma with supportive care
– Heavy metal poisoning if chelation therapy started early
Guarded Prognosis
– Severe CNS trauma with permanent deficits likely
– Fungal infections depending on which fungus
– Tumors if amenable to complete surgical removal
Poor Prognosis
– Rabies and other viral encephalitides
– Toxoplasmosis, sarcocystosis, and parasitic infections
– Lead poisoning if chronic and advanced
– Brain cancer, especially gliomas, often fatal
The expertise of the veterinary team, diagnostic capabilities, and owner commitment to treatment impact the outcome significantly. Even severe neurological dysfunction can potentially be managed with dedicated nursing care and physical therapy.
Key Takeaways
– Neurological disorders in birds have many possible causes including infectious diseases, toxins, metabolic dysfunction, trauma, congenital issues, and cancer.
– Diagnostics like bloodwork, imaging studies and biopsies help determine the underlying problem.
– Supportive care and treatment of the primary condition are the main approaches to managing neurological disease.
– Preventative care through proper husbandry, nutrition, safe environment and routine veterinary visits is key to reducing neurological risks.
– Prognosis depends on cause but is generally worse for viral infections, significant CNS trauma, and brain tumors.
– With intensive therapy and nursing care, even birds with severe deficits may have decent quality of life.
