Principles of Therapy of Neurologic Disease: Nervous System Introduction: Merck Veterinary Manual
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`10/8/16, 3:42 PM
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`Merck Manual > Veterinary Professionals > Nervous System >
`Nervous Systep Introduction
`Principles of Therapy of Neurologic Disease
`
`Also see Systemic Pharmacotherapeutics of the Nervous System.
`
`Seizure Control
`Status epilepticus (continuous or cluster seizures) in dogs and cats
`may be interrupted by diazepam, given at 0.5 mg/kg (not to exceed 10
`mg at one time), IV. Sodium pentobarbital to effect, not to exceed 3-15
`mg/kg, IV, may also be used, followed by phenobarbital at 2-4 mg/kg,
`IV, every 6 hr. A better alternative is to give propofol as a constant rate
`infusion at 0.1-0.6 mg/kg/min, followed by a loading dose of
`phenobarbital (if the animal is not already on phenobarbital) of 2-4
`mg/kg IV every 6 hr for a total of four doses. Diazepam given at 0.5-
`1.0 mg/kg/hr as a constant-rate infusion may be used to control
`persistent status epilepticus. If the animal has a preexisting hepatic
`condition that precludes the use of phenobarbital, then levetiracitam
`40-60 mg/kg may be given IV, SC,or rectally, resulting in a therapeutic
`blood level that will persist for 9 hours. Oral anticonvulsants should be
`resumed as soon as possible if currently being given.
`
`Recommended maintenance anticonvulsant therapy in dogs and cats
`is phenobarbital at 2-4 mg/kg, PO, bid, as needed to control seizures
`or to maintain serum levels at 15-40 mcg/mL. Dogs can be treated
`with potassium bromide (KBr), 22-44 mg/kg given with food until the
`serum level is 1,500-3,000 mcg/mL. Because KBr has a long half-life,
`if started at maintanance levels, the steady state therapeutic level will
`not be reached until 3 mo after initiation of therapy. Phenobarbital may
`become clinically effective in 72 hr, whereas KBr may take several
`weeks. The longterm efficacy of phenobarbital and KBr is about the
`same. However, KBr bypasses the liver, so it is better than
`phenobarbital in animals with liver disease. Animals taking
`phenobarbital often have increased liver enzymes and cholesterol
`levels but decreased thyroid levels; these should be expected and
`often do not require treatment. KBr has also been linked with
`megaesophagus and pancreatitis in dogs. Because KBr is not
`commercially available, it may be prepared by a compounding
`
`http://www.merckvetmanual.com/mvm/nervous_system/nervous_system_introduction/principles_of_therapy_of_neurologic_disease.html
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`Principles of Therapy of Neurologic Disease: Nervous System Introduction: Merck Veterinary Manual
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`10/8/16, 3:42 PM
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`pharmacist by mixing KBr crystals in water to give a concentration of
`250 mg/mL or by packing the crystals in gelatin capsules. KBr serum
`levels are affected by the salt content of the diet, so the diet should be
`consistent; the higher the dietary salt content, the faster the bromide is
`excreted via the kidneys. KBr has proved more efficacious than
`phenobarbital in dogs with cluster seizures and for seizures that are
`difficult to control. Phenobarbital and KBr may be given in combination.
`Diazepam is not an effective longterm oral anticonvulsant in dogs
`because of its short half-life; however, a compounding pharmacist can
`prepare rectal suppositories containing diazepam 0.5-2 mg/kg for
`home use in dogs with cluster seizures, or the injectable form can be
`given rectally at 1 mg/kg to prevent trips to emergency clinics. The
`tertiary anticonvulsants, levetiracitam and zonisamide, are quickly
`gaining greate (cid:9)
`especially has shown great efficacy
`GET
`in controlling (cid:9)
`:nimals with a poor response to
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`O
`phenobarbital CONTENT
`KBr may cau
`recommended
`cats with unc
`however, in o
`necrosis in cat
`few weeks of
`cats; if seizur
`Acupuncture
`
`so its use in cats is no longer
`mg/kg, PO, bid, may be used in
`=:-..ause of its longer half-life in cats;
`was associated with fatal hepatic
`lose monitoring throughout the first
`I is the anticonvulsant of choice in
`oiled, then levetiracitam is added.
`of seizures in all species.
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`Acute Spinal Cord Injury
`Acute spinal cord injury from trauma, intervertebral disc herniation, or
`fibrocartilaginous embolization resulting in paraplegia must be treated
`aggressively in dogs to ensure the best chance for recovery. If the
`animal is seen within the first 8 hr after injury, methylprednisolone
`sodium succinate or prednisolone sodium succinate is given at 30
`mg/kg, IV, followed by 15 mg/kg in 2 and 6 hr, or a constant IV infusion
`to give a total dose of 60 mg/kg. Steroid use is not advised if it has
`been longer than 8 hr since the trauma occurred, because there may
`be more deleterious effects than beneficial ones. Dexamethasone is
`not used. Oral famotidine at 0.5-1 mg/kg, once or twice daily;
`cimetidine at 5-10 mg/kg, bid; or misoprostol at 3 mcg/kg, bid, can be
`used to protect the GI tract. Polyethylene glycol (PEG) 30% solution
`may be given IV at 2.2 mL/kg, then repeated in 24 hr. PEG is a newer
`treatment that appears promising. If the injury occurred more than 72
`hr before treatment, the benefit of PEG is questionable. For maximal
`benefit, decompressive spinal surgery should be performed as soon as
`possible, usually within 24 hr, when indicated.
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`Principles of Therapy of Neurologic Disease: Nervous System Introduction: Merck Veterinary Manual
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`10/8/16, 3:42 PM
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`Anti-Inflammatory Drugs
`For control of CNS inflammation in dogs and cats unassociated with a
`virus or other agent, prednisone at 2 mg/kg/day may be given PO. Oral
`famotidine at 0.5-1 mg/kg, once or twice daily; cimetidine at 5-10
`mg/kg, bid; or misoprostol at 3 mcg/kg, bid, is given to prevent GI
`irritation. If GI ulcers develop and melena is detected, sucralfate (500
`mg for cats and dogs <20 kg; 1 g for dogs >20 kg), PO, tid-qid, is given
`2 hr apart from other drugs. NSAIDs should never be given in
`conjunction with steroids, because GI ulceration is common. The
`dosages of all steroids given should be slowly tapered; abrupt
`withdrawal should be avoided. Prednisone can be used as longterm
`maintenance therapy on alternate days to avoid complete suppression
`of adrenal function. Other chemotherapeutics used for inflammatory
`CNS disease such as MUE are cytarabine (50 mg/m2, SC, bid for 2
`days, then repeated at 3-4 wk intervals), mycophenolate (10 mg/kg,
`PO, bid), and cyclosporine (5 mg/kg, PO, bid).
`
`Antiedema Drugs
`After cranial surgery and in animals with brain tumors or head injuries
`that cause a declining neurologic status, 20% mannitol, 0.5-1 g/kg,
`may be given slowly IV. Mannitol is not given in spinal cord injuries.
`Use of methylprednisolone sodium succinate as described above for
`acute spinal cord injury is no longer recommended for head injuries in
`people, and its use in the veterinary field is declining. For palliative
`treatment of brain tumors, oral prednisone may be used.
`
`Muscle Relaxants
`Diazepam at 0.5 mg/kg or methocarbamol at 40 mg/kg, PO, tid-qid,
`relieves muscle spasms from intervertebral disc protrusion and other
`sources of nerve root irritation.
`
`Antimicrobial Therapy
`Refer to discussions of specific infections for antimicrobial therapy
`recommendations.
`
`Nursing Care
`Animals with paraplegia and quadriplegia need intensive nursing care.
`The animal should be maintained on padding and turned every 4-6 hr
`to avoid decubital ulcers. The bladder must be expressed or
`catheterized every 6-8 hr. In paraplegic animals, diazepam may be
`given to facilitate relaxation of the urinary sphincter, making manual
`expression of the bladder easier. Urine must be monitored for evidence
`of cystitis. The skin must be kept clean and free of urine and feces to
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`Principles of Therapy of Neurologic Disease: Nervous System Introduction: Merck Veterinary Manual
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`10/8/16, 3:42 PM
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`prevent dermatitis. Quadriplegic animals may need to be hand fed
`nutritious food and given plenty of water. Manual extension and flexion
`of joints and muscle massage will help delay contractures and muscle
`atrophy in paralyzed limbs.
`
`Last full review/revision July 2013 by Thomas Schubert, DVM, DACVIM, DABVP
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