History
A 3-month-old 6-kg sexually intact female Siberian Husky was referred for evaluation of coughing, lethargy, and anorexia of 1 week's duration. The dog lived in a rural environment and had outdoor access; its vaccination status and antiparasitic treatments were current.
Clinical and Gross Findings
Physical examination of the dog revealed a dry cough, mild tachypnea, and increased bronchovesicular sounds bilaterally during lung auscultation. Oxygen saturation (as measured by pulse oximetry) was 98% in room air. A CBC revealed leukocytosis (28.32 × 103 WBCs/μL; reference interval, 5.05 × 103 to 16.76 × 103 WBCs/μL) characterized by neutrophilia (21.56 × 103 neutrophils/µL; reference interval, 2.95 × 103 to 11.64 × 103 neutrophils/µL) and monocytosis (2.54 × 103 monocytes/μL; reference interval, 0.16 × 103 to 1.12 × 103 monocytes/μL). Additionally, the dog had mild normocytic and hypochromic anemia (Hct, 29.5%; reference interval, 37.3% to 61.7%). Thoracic radiography revealed an alveolar pattern consistent with pneumonia at the level of the right cranial lung lobe. Testing for circulating antibodies against Ehrlichia canis, Anaplasma phagocytophilum, Borrelia burgdorferi, and Dirofilaria immitis antigen yielded negative results, and toxoplasmosis and neosporosis were ruled out. A PCR assay of a urine sample did not detect canine distemper virus.
The dog was hospitalized, during which time it developed progressively worsening neurologic signs. Initially, the dog was alert and responsive but became progressively obtunded with ambulatory tetraparesis. The owner declined further investigations, and the dog was treated with amoxicillin–clavulanic acid (20 mg/kg, IV, q 8 h), maropitant (1 mg/kg, IV, q 24 h), fenbendazole (50 mg/kg, PO, q 24 h), and IV fluids. Four days after presentation, the dog's condition deteriorated further with development of stupor and non-ambulatory tetraparesis. Cranial nerve assessment revealed bilateral miosis, absent menace responses, spontaneous rotatory nystagmus with the fast phase to the right, absent physiologic oculocephalic reflexes, and absent gag reflex. Proprioception was delayed in all 4 limbs, and spinal reflexes were intact. There was no hyperesthesia evident on palpation of the vertebral column. Given deterioration of the dog's condition, the owner elected euthanasia. Owner consent was only given for the histologic examination of the encephalon, which was removed and fixed in neutral-buffered 10% formalin.
In transverse section, the brain had marked dilation of the lateral ventricles and third ventricle. The ventricles, especially the left lateral ventricle, were filled with a mucoid to fibrillary, compacted, brown to gray material (Figure 1).
Photograph of a transverse cut section of the brain (at the level of the thalamus) of a 3-month-old Siberian Husky that had a history of coughing, lethargy, and anorexia of 1 week's duration and subsequently developed progressive neurologic signs. Notice the moderate to marked dilation of the ventricular system. The ventricles, especially the left lateral ventricle, are filled with a mucoid to fibrillary, compacted, brown to gray material.
Citation: Journal of the American Veterinary Medical Association 259, 10; 10.2460/javma.19.05.0227
Histopathologic Findings
Microscopically, the material in the ventricular system was mainly composed of an inflammatory infiltrate, consisting of polymorphic neutrophils and activated histiocytic cells with extensive and vacuolated cytoplasm (Figure 2). In the right lateral ventricle, a fragment of vegetative material surrounded by the same inflammatory infiltrate was identified (Figure 3). In the lateral ventricles, the vessels inside the choroid plexus were disrupted with multiple intraventricular hemorrhages. Externally, these vessels were surrounded by a similar inflammatory infiltrate. The mesencephalic aqueduct was filled with a similar inflammatory component that also extended, although to a lesser extent, to the third ventricle. The ventricular wall had discontinuity of the ependymal layer and severe spongiosis of the neuropil. At that level, there was some perivascular cuffing, mainly composed of histiocytic cells and macrophages with few lymphocytes. The internal capsule, caudate nuclei, parietotemporal subcortical white matter, periaqueductal gray matter, medial longitudinal fasciculus, and medial vestibular nuclei had diffuse gliosis and mild spongiosis with generalized vessel congestion. This inflammatory infiltrate was also present in the subarachnoid space surrounding the brain.
Photomicrographs of a transverse section of the brain at the level of the thalamus. A—The left lateral ventricle is filled with a basophilic fibrillary, compacted material. H&E stain; bar = 10 mm. B—The material in the ventricular system is mainly an inflammatory infiltrate composed of polymorphic neutrophils and activated histiocytic cells. H&E stain; bar = 250 μm.
Citation: Journal of the American Veterinary Medical Association 259, 10; 10.2460/javma.19.05.0227
Photomicrographs of a transverse section of the brain. A—In the right lateral ventricle, notice a fragment of a vegetal material surrounded by an inflammatory fibrillary infiltrate (arrow). H&E stain; bar = 10 mm. B—The choroid plexus of the right lateral ventricle is infiltrated by inflammatory material mainly composed of polymorphic neutrophils and activated histiocytic cells. Vegetative material is also present (arrow). H&E stain; bar = 2.5 mm. C—In another view, plant material is evident in the right lateral ventricle. H&E stain; bar = 250 μm.
Citation: Journal of the American Veterinary Medical Association 259, 10; 10.2460/javma.19.05.0227
Morphologic Diagnosis and Case Summary
Morphologic diagnosis: generalized severe pyogranulomatous ventriculitis, choroiditis, and granulomatous meningoencephalitis.
Case summary: plant-based foreign body in the lateral ventricle of a dog.
Comments
Migration of plant material is a common cause of foreign body–related disease in animals.1 Grass awns are especially prone to migration because of their sharp and pointed shape, which facilitates cutaneous or mucosal penetration and progressive forward movement.1,2 In small animals, the areas more commonly affected by plant-based foreign bodies are the external ear canal, oral and nasal cavities, inter-digital web, and conjunctiva, as well as the subcutaneous tissues of the head, face, neck, flanks, and costochondral areas.1,3 The associated clinical signs are highly variable and depend on the affected zone of the body and the degree of inflammation caused by the foreign body.4
Intracranial migrating foreign bodies in domestic animals have rarely been documented, and the most commonly reported causes include porcupine quills,5,6 oropharyngeal foreign bodies of various kinds,7,8 sewing needles,9 or plant material.2,4,10,11 To the authors' knowledge, there are 5 cases of dogs with an intracranial plant foreign body reported in the veterinary medical literature.2,4,11 In 2005, Dennis et al2 reported 3 cases, the first of which was a 5-month-old spayed female crossbreed dog with a history of acute brainstem signs. The necropsy of that dog revealed acute suppurative meningoencephalitis and ventriculitis, and a plant foreign body was observed in the lateral ventricle, as found in the dog of the present report. The second case involved a 4-month-old sexually intact male Great Dane with brainstem signs and tonic-clonic muscular contractions. Postmortem examination and histologic examination of brain specimens revealed subacute fibrinosuppurative meningoencephalitis and ventriculitis, and a grass awn was located crossing the right occipital lobe, internal capsule, and rostral horn of the lateral ventricle. The third case involved a 4-year-old sexually intact female Brittany with a history of acute forebrain and brainstem signs. Necropsy of that dog revealed chronic suppurative meningoencephalitis of the occipital lobe and ventriculitis, and plant material was found within the dura mater.2 In 2007, Mateo et al4 reported a case involving a 7-month-old Dachshund with a history of acute brainstem signs. Necropsy revealed a caudal brainstem abscess affecting the pons and medulla oblongata and surrounding a plant foreign body.4 In 2015, Lazzerini et al11 described a 22-month-old Magyar Vizsla with acute forebrain neurologic signs, including seizures. On postmortem examination, meningoencephalitis attributable to a plant foreign body in the calvarium that had penetrated the cerebral parenchyma at the level of the right hemisphere was diagnosed. This was the first canine case of intracranial plant material migration with seizures as the presenting sign.11 In all 5 reported cases, postmortem evaluation identified severe meningoencephalitis; in 3 of the 5 cases, ventriculitis was found.2,4,11 The foreign body was found in the lateral ventricle in 2 of the 5 dogs.2,4,11
The reported cases of intracranial plant material foreign bodies in dogs involved young animals with acute neurologic signs. In the case described in the present report, the owner retrospectively reported that the dog had played in a field of grass awns and had had a few sneezing episodes before the initial clinical signs became evident. Migration routes for plant material in cases of brain vegetal migrations have been generally unclear. For the dog of the present report, only necropsy of the brain was permitted, and no migratory tracts were identified macroscopically or microscopically in the cranium. However, considering that the dog's clinical history started with respiratory tract signs, a first-step migration through the airways was suspected. Inhalation or ingestion of an awn could have also caused penetration of the bronchial or esophageal mucosa, resulting in lobar pneumonia or chronic pleuritis.2,3,12
In vivo diagnosis of an intracranial vegetal foreign body is challenging, and in all reported cases a postmortem diagnosis was achieved.2,4,11 Magnetic resonance imaging of the brain may reveal signs of inflammatory or infectious diffuse meningoencephalitis or features of an abscess or neoplasia.4,11 It was not possible to confirm the foreign plant material with MRI in any of the previously reported cases. In 2 of the cases,2,11 analysis of a CSF sample revealed neutrophilic pleocytosis with a high protein content. Culture of the CSF sample yielded no growth in 1 case11 and had positive results in 3 other cases.2 Treatment with antimicrobials and anti-inflammatory dosages of glucocorticoids has been attempted and achieved prompt mild improvement of the clinical signs, but unfortunately, the condition of all affected dogs deteriorated and they were euthanized.
Although uncommon, brain migration of a plant-based foreign body should be included in differential diagnoses of dogs with meningoencephalitis and ventriculitis or multifocal clinical signs consistent with an inflammatory or infectious brain disease. However, owing to the severity of the clinical signs, diagnostic difficulty, and mild response to medical treatment, the prognosis for dogs with an intracranial plant material foreign body is poor.
Acknowledgments
The authors have no conflicts of interest to disclose.
References
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