Technical Note: Validation of the effectiveness of electric stunning for euthanasia of mature swine (Sus scrofa domesticus).

Electrocution and the use of a penetrating captive bolt gun (PCBG) are both acceptable methods of euthanasia for market weight swine. Research has demonstrated that a PCBG is effective in both growing and mature swine. Given limited to no published research base on electrocution in mature swine, the objectives of the present study were to evaluate the efficacy of a two-stage (head only followed by head to heart, 10 s contact for each) mobile electric stunner (E-STUN, Hubert HAAS TBG 96N) and to assess euthanasia outcomes when comparing E-STUN with the frontal placement of a heavy-duty PCBG (Jarvis, In-line Cylinder Style) when applied to heavy-weight (>200 kg) mature boars and sows. Effectiveness of the E-STUN and PCBG was evaluated first in unconscious anesthetized mature swine (n = 7 boars and sows per treatment; average weight 282 ± 48 kg, n = 28) to reduce the risk of failure in a conscious animal and then in conscious mature swine (n = 3 boars and sows per treatment; average weight 282 ± 63 kg, n = 12). Data from both stages were combined for analyses. Treatment efficacy was defined as any pig that achieved cardiac and respiratory arrest within 10 min after treatment application. A three-point traumatic brain injury score (0 = normal; 1 = some abnormalities; and 2 = grossly abnormal, unrecognizable) was used to evaluate six neuroanatomical structures (cerebral cortex, cerebellum, hypothalamus, thalamus, pons, and brain stem), and the presence of intracranial hemorrhage was also noted. All animals were immediately rendered insensible with E-STUN and PCBG, and no difference was noted between treatments for the detection of corneal reflex following treatment application (P = 0.11). Rhythmic breathing was absent following the administration of either E-STUN or PCBG. When evaluating the time to last heartbeat, there was a significant interaction between sex and treatment. Boars euthanized via E-STUN had a 346.8-s decrease in time to last heartbeat compared with boars euthanized via PCBG (P < 0.001), and females euthanized via E-STUN had a 479.3-s decrease in time to last heartbeat compared with females euthanized via PCBG (P < 0.001). Intracranial hemorrhage was common for both methods, and visible disruption of neural tissue was evident due to the physical nature of the PCBG. This study demonstrated that a mobile E-STUN system is as effective as a heavy-duty PCBG in inducing insensibility and death and shows promise as an alternative method for euthanizing mature pigs on-farm.

Euthanasia is a moral obligation of all individuals working in the swine industry. A majority of acceptable methods have been validated for market weight pigs, while less attention has focused on heavy-weight mature boars and sows. The objectives of the current study were to evaluate the effectiveness of a mobile electric stunner (E-STUN) as a method of humane euthanasia in heavy-weight mature boars and sows and to assess the outcomes when compared with a penetrating captive bolt gun (PCBG) method. The efficacy of the treatment was defined as any pig that achieved cardiac and respiratory arrest within 10 min after treatment application. The amount of traumatic brain injury was evaluated across the brain, and the presence of intracranial hemorrhage was also noted. All animals were immediately rendered insensible, and rhythmic breathing was absent following either treatment application. Boars and sows had a decreased time to last heartbeat with the E-STUN when compared with the PCBG method. Intracranial hemorrhage was common for both methods, and visible disruption of brain tissue was evident due to the physical nature of the PCBG. This study demonstrated that a mobile E-STUN is as effective as a PCBG for humane euthanasia of heavy-weight mature swine.

A pilot study evaluating the effect of mannitol and hypertonic saline solution in the treatment of increased intracranial pressure in 2 cats and 1 dog naturally affected by traumatic brain injury.

OBJECTIVE: To evaluate the effects of iso-osmolar doses of 18% mannitol and 3% sodium chloride (NaCl) solutions in decreasing intracranial pressure (ICP) in animals with severe traumatic brain injury (TBI). DESIGN: Prospective uncontrolled interventional study. SETTING: Veterinary university teaching hospital. ANIMALS: Two cats and 1 dog with TBI with a modified Glasgow Coma Scale score ≤8 after hemodynamic stabilization, and with brain magnetic resonance imaging changes suggestive of intracranial hypertension. INTERVENTIONS: Animals were surgically instrumented for direct ICP measurement, then randomly treated with iso-osmolar doses of 18% mannitol or 3% NaCl. Direct ICP and cerebral perfusion pressure (CPP) were recorded both before treatment and for 120 minutes following drug administration. MEASUREMENTS AND MAIN RESULTS: Direct ICP and CPP were recorded both before treatment and at 5 additional time points following administration over the subsequent 120 minutes. Case 1 received 3% NaCl without any response to therapy; refractory posttraumatic hypertension was suspected. Case 2 was treated with 3% NaCl; ICP decreased by 40.7% and CPP increased by 15%; however, these effects were transient. Case 3 received 18% mannitol, and ICP decreased by 19% and CPP increased to normal. However, there was a rebound increase in ICP that was higher than pretreatment values, and CPP decreased slightly before it gradually increased to normal values towards the end of the study. CONCLUSIONS: Both mannitol and hypertonic saline decrease ICP and improve CPP, but the effect observed in this pilot study suggests that there might be differences in the duration of these effects. Appropriately designed studies in a larger and homogeneous population are warranted to further investigate these findings.

Use of the T2*-weighted gradient recalled echo sequence for magnetic resonance imaging of the canine and feline brain.

T2*-weighted magnetic resonance imaging (MRI) has been reported to help improve detection of intracranial hemorrhage and is widely used in human neuroimaging. To assess the utility of this technique in small animals, interpretations based on this sequence were compared with those based on paired T2-weighted and fluid-attenuated inversion recovery (FLAIR) sequences in 200 dogs and cats that underwent brain MRI for suspected intracranial disease. Two sets of images (T2 + FLAIR and T2*) were reviewed separately in random order unaccompanied by patient information and were interpreted as normal or abnormal based on whether intracranial abnormalities were seen. The number and location of intracranial lesions were recorded. Eighty-five studies were considered normal and 88 were considered abnormal based on both sets of images, with good agreement (κ = 0.731) between the two. Susceptibility artifact was present in 33 cases (16.5%) on T2*-weighted images. In 12 cases (6%) a total of 69 lesions were seen on T2*-weighted images that were not seen on T2/FLAIR, all of which were associated with susceptibility artifact caused by presumed intracranial hemorrhage. Pseudolesions were seen on T2*-weighted images in five cases, none of which were associated with susceptibility artifact. Abnormalities were seen on T2/FLAIR images that were not seen on T2*-weighted images in 35 cases, confirming that T2* does not replace standard spin echo sequences. These results support inclusion of T2*-weighted sequences in small animal brain MRI studies and indicate that that a large number of abnormalities (especially hemorrhagic lesions) can go undetected if it is not performed.

Interobserver agreement and diagnostic accuracy of brain magnetic resonance imaging in dogs.

OBJECTIVE: To evaluate interobserver agreement and diagnostic accuracy of brain MRI in dogs. DESIGN: Evaluation study. ANIMALS: 44 dogs. PROCEDURES: 5 board-certified veterinary radiologists with variable MRI experience interpreted transverse T2-weighted (T2w), T2w fluid-attenuated inversion recovery (FLAIR), and T1-weighted-FLAIR; transverse, sagittal, and dorsal T2w; and T1-weighted-FLAIR postcontrast brain sequences (1.5 T). Several imaging parameters were scored, including the following: lesion (present or absent), lesion characteristics (axial localization, mass effect, edema, hemorrhage, and cavitation), contrast enhancement characteristics, and most likely diagnosis (normal, neoplastic, inflammatory, vascular, metabolic or toxic, or other). Magnetic resonance imaging diagnoses were determined initially without patient information and then repeated, providing history and signalment. For all cases and readers, MRI diagnoses were compared with final diagnoses established with results from histologic examination (when available) or with other pertinent clinical data (CSF analysis, clinical response to treatment, or MRI follow-up). Magnetic resonance scores were compared between examiners with κ statistics. RESULTS: Reading agreement was substantial to almost perfect (0.64 < κ < 0.86) when identifying a brain lesion on MRI; fair to moderate (0.14 < κ < 0.60) when interpreting hemorrhage, edema, and pattern of contrast enhancement; fair to substantial (0.22 < κ < 0.74) for dural tail sign and categorization of margins of enhancement; and moderate to substantial (0.40 < κ < 0.78) for axial localization, presence of mass effect, cavitation, intensity, and distribution of enhancement. Interobserver agreement was moderate to substantial for categories of diagnosis (0.56 < κ < 0.69), and agreement with the final diagnosis was substantial regardless of whether patient information was (0.65 < κ < 0.76) or was not (0.65 < κ < 0.68) provided. CONCLUSIONS AND CLINICAL RELEVANCE: The present study found that whereas some MRI features such as edema and hemorrhage were interpreted less consistently, radiologists were reasonably constant and accurate when providing diagnoses.

Concurrent medical conditions and long-term outcome in dogs with nontraumatic intracranial hemorrhage.

Nontraumatic intracranial hemorrhage is bleeding originating from the brain or surrounding structures. It results from blood vessel rupture and may be primary or secondary in origin. The magnetic resonance imaging (MRI) characteristics of 75 dogs with nontraumatic intracranial hemorrhage were reviewed to determine signalment; intracranial compartment involved, size and number of lesions; type and prevalence of concurrent medical conditions; and long-term outcome. Hemorrhagic lesions were intraparenchymal (n = 72), subdural (n = 2) or intraventricular (n = 1). Thirty-three of 75 dogs had a concurrent medical condition. A concurrent condition was detected in 13 of 43 dogs with a single lesion ≥5 mm and included Angiostrongylus vasorum infection, intracranial lymphoma and meningioma. Of the 20 dogs with multiple lesions ≥5 mm, 7 had A. vasorum infection, 2 had hemangiosarcoma metastasis, 5 had suspected brain metastasis, and 1 was septicemic. Of the 12 dogs with multiple lesions, 2 had hyperadrenocorticism, 2 had chronic kidney disease, and 1 had hypothyroidism. Of these five dogs, all were hypertensive and four died within 12 months. No dog had a single lesion <5 mm. Long-term outcome was favorable in 26 of 43 dogs with single lesions ≥5 mm, 6 of 20 dogs with multiple lesions ≥5 mm, and 8 of 12 dogs with multiple lesions <5 mm. A. vasorum infection was the most common concurrent condition in dogs with nontraumatic intracranial hemorrhage (16/75), with an excellent outcome in 14 of 16 dogs. Prognosis in nontraumatic intracranial hemorrhage is reported in terms of concurrent medical conditions and the number and size of lesions.

Imaging diagnosis: CT findings in a dog with intracranial hemorrhage secondary to angiostrongylosis.

A seven-month-old Cocker Spaniel had a cough, acute lethargy, decreased responsiveness, and episodes of hyperexcitability. There were bilateral generalized increased lung sounds, bilateral episcleral hemorrhage, and systemic hypertension. Prolonged buccal mucosal bleeding time and elevated D-dimer concentrations were detected. Radiographically, there was a generalized moderate unstructured interstitial pattern. In thoracic CT images, there was a diffuse moderate hyperattenuating appearance of the bronchial walls and interstitium and diffuse areas of moderate bronchiectasis. The brain CT images were characterized by marked hyperattenuating well-defined masses. In addition, there were smaller hyperattenuating and hypoattenuating masses scattered throughout the cerebral and cerebellar parenchyma. A zinc sulphate flotation test confirmed large numbers of Angiostrongylus vasorum L1 larvae. Despite therapy the dog continued to deteriorate and underwent euthanasia. Postmortem examination confirmed the presence of multiple intracranial and extracranial hemorrhages. Angiostrongylosis should be considered as one of the differential diagnoses in dogs presenting with neurologic signs consistent with acute intracranial haemorrhage.

Imaging diagnosis--Hemorrhagic meningioma.

An 8-year-old Labrador Retriever developed acute central vestibular signs. An extra-axial mass was detected on MR images ventral to the brainstem. The mass was both T1- and T2-hypointense; there was also thin-rimmed patchy contrast enhancement. These findings were nonspecific, but the extreme T2-hypointensity was notable and suggested a hemorrhagic mass. The histologic diagnosis was anaplastic meningioma with acute hemorrhage. These findings document an unusual appearance of a meningioma in MR images due to intratumoral hemorrhage.

Craniotomy with cystoperitoneal shunting for treatment of intracranial arachnoid cysts in dogs.

OBJECTIVE: To describe a technique of decompressive craniotomy with cystoperitoneal shunt (CPS) placement for treatment of canine intracranial arachnoid cyst (IAC), and to evaluate outcome in 4 dogs. STUDY DESIGN: Retrospective study. ANIMALS: Dogs (n=4) with IAC. METHODS: Medical records of dogs diagnosed with IAC by magnetic resonance imaging (MRI; 3 dogs) or computed tomography (CT; 1 dog) were evaluated. All dogs had varying degrees of neurologic dysfunction before surgery. A combined lateral (rostrotentorial)/suboccipital craniotomy was performed sacrificing the transverse sinus on the operated side. The rostral (ventricular) end of a low-pressure valve shunt (3.0 mm outer diameter, 7.0 cm length) was placed transversely into the cyst cavity; the distal end was placed in the peritoneal cavity. All dogs were rechecked at various intervals by >or=1 of the authors either directly, by telephone consultation with owners, or both. Three dogs were imaged postoperatively (CT-1 dog; MRI-1; ultrasonography-1). RESULTS: Intraoperative complications were limited to excessive transverse sinus hemorrhage requiring blood transfusion in 1 dog. There were no postoperative complications. Clinical signs of neurologic dysfunction resolved in 3 dogs and improved substantially in 1 dog. The latter dog required long-term, low-dose corticosteroid therapy. No dogs required repeat surgery. Mean follow-up time was 23.8 months (range, 12-43 months). Collapse of the intracranial cyst was verified in 3 dogs with repeat imaging. In 2 dogs, there was no evidence of the cyst on CT or MRI; in the third dog, a small amount of fluid was demonstrated rostral to the cerebellum on ultrasonography, but there was no identifiable cyst. In 1 dog, the rostral aspect of the shunt had shifted; however, this was not associated with any clinical deterioration. CONCLUSION: Craniotomy with CPS placement was well tolerated and resulted in sustained improvement or resolution of dysfunction. Cyst decompression was verified in 3 dogs that were re-imaged. None of the patients required re-operation. Excessive transverse sinus hemorrhage is a potential danger that may necessitate blood transfusion. Other IAC patients treated with this method will need to be evaluated to fully evaluate its effectiveness. CLINICAL SIGNIFICANCE: Craniotomy with CPS placement may be an effective treatment method for dogs clinically affected with IAC.

Intracranial haemorrhage associated with Angiostrongylus vasorum infection in three dogs.

This report describes three dogs with intracranial haemorrhage secondary to severe coagulation defects associated with Angiostrongylus vasorum infection. The initial case was diagnosed at necropsy, with two subsequent cases diagnosed antemortem and successfully treated. The dogs ranged in age from 14 months to four years and were presented for evaluation of a severe, subacute onset of suspected cerebral disease. Magnetic resonance imaging performed on all three dogs was suggestive of multiple areas of intraparenchymal brain haemorrhage. Coagulation assays showed a consumptive coagulopathy resembling chronic disseminated intravascular coagulation. Postmortem examination of the initial case confirmed the presence of multiple intracranial and extracranial haemorrhages. An unexpected finding was that of a marked multifocal nematode infection of the lungs with an associated vasculopathy. The parasites were confirmed to be A vasorum. In the two other dogs, faecal examination by Baermann technique confirmed A vasorum infection. Both dogs were treated with fenbendazole and one was additionally given a plasma transfusion. Repeated coagulation assays were normal within one week. Neurological examinations were normal for both dogs within six weeks. This case series indicates that A vasorum infection should be considered as a possible aetiology of intracranial haemorrhage in dogs.

Suspected pituitary apoplexy in a German shorthaired pointer.

Pituitary apoplexy is a syndrome which has been described in humans caused by acute haemorrhage or infarction within a pituitary tumour or a non-tumorous pituitary gland. This report describes the authors' observations of a dog in which vomiting, visual disturbances, seizures, altered consciousness and diencephalic dysfunction occurred in association with haemorrhage originating from a pituitary macroadenoma. The clinical signs were thought to be consistent with disruption of the hypothalamus and brainstem, together with raised intracranial pressure due to intraventricular haemorrhage. These signs, and the pathological findings, bear a striking resemblance to those associated with the syndrome of pituitary apoplexy, seen in humans.

Intracranial intra-arachnoid cyst with intracystic hemorrhage in two dogs.

Clinical signs, magnetic resonance imaging (MRI) features, treatment, and outcome of two adult dogs with neurologic dysfunction resulting from hemorrhage into a quadrigeminal intracranial intra-arachnoid cyst are described. In dog 1, the cyst was hyperintense to cerebrospinal fluid (CSF) on T1-weighted MRI and hypointense to CSF on T2-weighted images. In dog 2, the cyst was isointense to CSF on T1- and T2-weighted images. Both dogs were treated with craniotomy and cyst fenestration. A large blood clot was removed from the lumen of the cyst in each dog. Dog 1 is clinically normal 3.5 years post-surgery and has a persistent cyst. Dog 2 had a good initial response to therapy but was euthanized 2.5 years post-operatively due to generalized seizures. The late onset of clinical signs in these dogs most likely resulted from hemorrhage into the cyst. Surgical fenestration and hematoma removal appear to provide a satisfactory treatment for adult dogs with an intracranial intra-arachnoid cyst and intracystic hemorrhage. Persistence of the cyst may occur in some dogs.