Pharmacokinetics of single-dose intravenous levetiracetam administration in normal dogs

Objective: To determine plasma pharmacokinetics of levetiracetam after a single intravenous dose (60 mg/kg) in normal dogs using a high‐performance liquid chromatography assay validated for canine plasma. Design: Pharmacokinetic study. Setting: A university‐based canine research facility. Animals: Six healthy adult dogs. Interventions: Intravenous drug administration, multiple blood sample procurement. Measurements and main results: There were no obvious adverse effects associated with the intravenous (IV) bolus administration of levetiracetam in any of the dogs. Plasma levetiracetam concentrations remained above or within the reported therapeutic range for humans (5–45 μg/mL) for all dogs, for all time periods evaluated. Mean and median (in parentheses) values for pharmacokinetic parameters included the following: maximum plasma concentration, 254 μg/mL (254 μg/mL); half‐life, 4.0 hours (4.0 hours); volume of distribution at steady state, 0.48 L/kg (0.48 L/kg); clearance, 1.4 mL/kg/min (1.5 mL/kg/min); and median residence time, 6.0 hours (6.0 hours). Conclusions: In normal dogs, a 60 mg/kg IV bolus dose of levetiracetam is well tolerated and achieves plasma drug concentrations within or above the therapeutic range reported for humans for at least 8 hours after administration. Based on the favorable pharmacokinetics and tolerability demonstrated for IV levetiracetam in this study, in addition to previously demonstrated efficacy of oral levetiracetam, IV levetiracetam may be a useful treatment option for emergency management of canine seizure activity.     

Deleted in colorectal cancer (netrin‐1 receptor) antibodies and limbic encephalitis in a cat with hippocampal necrosis

A 7‐year‐old neutered female domestic shorthaired cat born in Poland and then moved to Japan presented to the local clinic with recent onset of convulsive cluster seizures and status epilepticus. Magnetic resonance imaging revealed bilateral swelling of the hippocampus with T2 hyperintensity and contrast enhancing image, suggesting hippocampal necrosis. The cat completely recovered after treatment with antiepileptic drugs (AED) and administration of prednisolone (1 mg/kg PO q24h for 4 days and tapered). However, cluster seizures reoccurred and developed into status epilepticus despite increasing doses of AED. Although the convulsions were resolved by other AEDs, stupor and renal failure developed, and the cat was euthanized. Pathological findings were consistent with hippocampal necrosis. Immunological analysis for leucine‐rich glioma inactivated 1 (LGI1) autoantibodies was negative, but antibodies against DCC (deleted in colorectal carcinoma) known as netrin‐1 receptor were found. This report describes a case of feline autoimmune limbic encephalitis and hippocampal necrosis that were presumably associated with DCC autoantibodies.     

Symblepharon secondary to ophthalmomyiasis externa in a dog

A 4-month-old crossbred female dog presented with complaints of poor vision and odd appearance of the eyes. At the age of a month, the animal was found lying in a railway road in a very bad condition and was rescued from death. At that time, the patient was presented with severe bilateral ocular discharge, and from both eyes, dipterous fly larvae were extracted. The dog was given symptomatic treatment (deworming, topical and systemic antibiotics, nutritional support) but never regained a normal eye appearance. At the time of the initial presentation, it had severe vision impairment because of bilateral cicatricial symblepharon, total in the left eye and occupying 3/4 of the cornea in the right eye. Surgery was proposed to attempt a resolution. Superficial keratectomy was performed in both eyes. After a midline incision in the cornea, the conjunctiva was dissected away. The conjunctiva was apposed to and sutured to the limbus and secured in the upper and lower conjunctival fornix. Additionally, in the left eye, a lateral canthotomy and canthoplasty were performed to enlarge the size of the eyelid opening. The corneal epithelium healed without complications, the patient regained vision, and after 36 months of follow-up, no recurrences were observed. To the authors' knowledge, this is the first report of symblepharon secondary to ophthalmomyiasis externa in a dog.     

Pneumothorax secondary to pulmonary thromboembolism in a dog

Objective – To describe a case of spontaneous pneumothorax secondary to pulmonary thromboembolism possibly associated with pituitary dependent hyperadrenocorticism.
Case Summary – A 7-year-old spayed female Collie weighing 26 kg was referred for evaluation of spontaneous pneumothorax. An exploratory thoracotomy was performed and revealed 2 lung lobes to be diffusely hemorrhagic and they were resected. Histologic examination of multiple sections documented diffuse thromboembolism. A 2–3 cm thrombus was visualized distal to the bifurcation of the pulmonary artery during an echocardiographic examination postoperatively. The dog was discharged to the owner after recovery from surgery. The thrombus had resolved at the 4-week recheck examination. Diagnosis of pituitary dependent hyperadrenocorticism was confirmed based on follow-up endocrine testing.
New or Unique Information Provided – This is the first report of pulmonary thromboembolism causing spontaneous pneumothorax in the dog.     

Priapism secondary to penile metastasis in a dog

A 4-year-old, male Newfoundland cross was presented for lethargy, anorexia, and dysuria. The main clinical finding was an enlarged and painful prostate gland. While the dog was hospitalized, priapism developed. Following euthanasia, microscopic examination revealed that a carcinoma involving both bladder and prostate gland had widely metastasized to the penile vasculature.     

Cervical syringohydromyelia secondary to a brainstem tumor in a dog

An 11-year-old male Pekingese was evaluated because of a history of head tilt. Neurologic examination revealed a right-sided head tilt, ataxia, scoliosis, and proprioceptive deficits. Diagnostic testing included magnetic resonance imaging (MRI) of the head and neck. After IV administration of gadopentetate dimeglumine, an extra-axial, highly contrast-enhanced mass in the brainstem, cerebellar herniation, and syringohydromyelia were detected via MRI. The dog was treated with corticosteroids and radiation therapy of the mass for 4 weeks (total dose, 42.5 Gy). Magnetic resonance imaging was repeated 9 weeks and 6 months after radiation therapy; compared with the initial findings, a reduction in the size of the brainstem mass was observed in both MRI scans. The third MRI scan also revealed a normal cerebellar shape, no evidence of herniation, and resolution of syringohydromyelia in the dog at that time. It is recommended that whenever syringohydromyelia is observed via MRI, a primary cause (cranial or caudal to the affected region) should be sought.     

Respiratory paralysis secondary to epidural anesthesia in a dog

Transient respiratory paralysis developed in a 12-year-old spayed female Cocker Spaniel that received an anesthetic epidurally for excisional biopsy of perianal masses. Paralysis developed almost immediately after injection of 2.5 ml of 2% lidocaine (1 ml/4.9 kg), and was managed by mechanical ventilation and appropriate fluid therapy IV until spontaneous respiration returned. The respiratory paralysis was attributed to the excessive cranial extent of the anesthetic block.     

Spinal cord injury secondary to electrocution in a dog

A 13‐year‐old, female spayed, crossbreed dog of 32 kg was presented for evaluation of peracute onset of non‐ambulatory tetraparesis after chewing an electrical wire. Neurological examination was consistent with a C1‐C5 myelopathy. Magnetic resonance imaging revealed a focal intramedullary lesion over the C2‐C3 vertebral bodies, which was confirmed to be an acute focal necrotising poliomyelopathy with subarachnoid and subdural haemorrhages on postmortem examination. This report describes the clinical, imaging and histopathological findings of this unusual type of spinal cord injury, and the effects of electrocution in the central nervous system of dogs.     

Exophthalmos secondary to zygomatic adenocarcinoma in a dog.

An 8-year-old Labrador Retriever developed unilateral exophthalmos over a 1-year period. Contrast radiography, surgical exploration, and histologic examination revealed the cause to be an adenocarcinoma arising from the zygomatic salivary gland or duct.     

Sinus mucocele secondary to craniofacial trauma in a dog

A sinsus mucocele formed in the frontal sinus of a dog secondary to obstruction of the nasofrontal opening. The dog was successfully treated by surgical enlargement of the nasofrontal opening, curettage of the sinus epithelium, and placement of a fat graft and drain in the sinus. Although mucocele formation is uncommon in animals, it should be considered as a differential diagnosis for masses of the sinonasal area. Characteristic radiographic and cytologic findings should alert the clinician to this diagnosis, and along with aggressive treatment, should shorten the diagnostic and treatment delay experienced by the dog in this report.     

Ligneous conjunctivitis secondary to a congenital plasminogen deficiency in a dog

CASE DESCRIPTION: A 7-month-old 16.6-kg (36.5-lb) sexually intact female Golden Retriever was evaluated because of progressive severe bilateral membranous conjunctivitis, oral lesions, nasal discharge, and cough. CLINICAL FINDINGS: Histologic examination of conjunctival biopsy specimens revealed findings consistent with ligneous conjunctivitis. Circulating plasminogen activity was repeatedly low, and congenital plasminogen deficiency was identified as the underlying cause of the ocular, oral, and respiratory lesions. TREATMENT AND OUTCOME: Topical and subconjunctival administrations of fresh frozen plasma (FFP), topical administration of cyclosporine, and oral administration of azathioprine had no effect on the conjunctival membranes. Excision of the membranes followed by intensive treatment with topical applications of heparin, tissue plasminogen activator, corticosteroid, and FFP and IV administration of FFP prevented membrane regrowth. Intravenous administration of FFP increased plasma plasminogen activity to within reference limits, improved respiratory and oral lesions, and resulted in weight gain; discontinuation of this treatment resulted in weight loss, signs of depression, and worsening of lesions. After euthanasia because of disease progression, necropsy findings included mild hydrocephalus; multifocal intestinal hemorrhages; and fibrinous plaques in the oral cavity, nasopharynx, trachea, esophagus, and pericardium. Microscopically, the plaques were composed of fibrin and poorly organized granulation tissue. Fibrin thrombi were present within vessels in the lungs, oral cavity, and trachea. CLINICAL RELEVANCE: In dogs, congenital plasminogen deficiency can occur and may be the underlying cause of ligneous conjunctivitis. A combination of surgical and medical treatments may improve conjunctival membranes, and administration of FFP IV appears to be effective in treating nonocular signs of plasminogen deficiency.