Sarcocystis caninum and Sarcocystis svanai n. spp. (Apicomplexa: Sarcocystidae) Associated with Severe Myositis and Hepatitis in the Domestic Dog (Canis familiaris).

There are several reports of Sarcocystis sarcocysts in muscles of dogs, but these species have not been named. Additionally, there are two reports of Sarcocystis neurona in dogs. Here, we propose two new names, Sarcocystis caninum, and Sarcocystis svanai for sarcocysts associated with clinical muscular sarcocystosis in four domestic dogs (Canis familiaris), one each from Montana and Colorado in the USA, and two from British Columbia, Canada. Only the sarcocyst stage was identified. Most of the sarcocysts identified were S. caninum. Sarcocysts were studied using light microscopy, transmission electron microscopy (TEM), and polymerase chain reaction. Based on collective results two new species, S. caninum and S. svanai were designated. Sarcocystis caninum and S. svanai were structurally distinct. Sarcocystis caninum sarcocysts were up to 1.2 mm long and up to 75 µm wide. By light microscopy, the sarcocyst wall was relatively thin and smooth. By TEM, the sarcocyst wall was "type 9", 1-2 µm thick, and contained villar protrusions that lacked microtubules. Bradyzoites in sections were 7-9 µm long. Sarcocysts of S. svanai were few and were identified by TEM. Sarcocystis svanai sarcocysts were "type 1", thin walled (< 0.5 µm), and the wall lacked villar protrusions but had tiny blebs that did not invaginate. DNA was extracted either from infected frozen muscle biopsies or formalin-fixed paraffin-embedded sections. Dogs were either singly infected with S. caninum or multiply co-infected with S. caninum and S. svanai (the result of a mixed infection) based on multilocus DNA sequencing and morphology. BLASTn analysis established that the sarcocysts identified in these dogs were similar to, but not identical to Sarcocystis canis or Sarcocystis arctosi, parasites found to infect polar bears (Ursus maritimus) or brown bears (Ursus arctosi), respectively. However, the S. caninum sequence showed 100% identify over the 18S rRNA region sequenced to that of S. arctica, a parasite known to infect Arctic foxes (Vulpes lagopus).

Long-term effect of cervical distraction and stabilization on neurological status and imaging findings in giant breed dogs with cervical stenotic myelopathy.

OBJECTIVES: To assess long-term clinical and imaging outcomes in giant breed dogs with cervical stenotic myelopathy treated surgically. STUDY DESIGN: Retrospective case series. ANIMALS: Dogs (n = 7). METHODS: All dogs had lateral or dorsolateral cord compression at 1 or more sites and were treated with cervical distraction and stabilization using PMMA plugs. Four dogs had follow-up CT or CT/myelography performed at least 6 months postoperatively. Spinal canal stenosis measurements were compared between pre- and postoperative CT images. Long-term clinical neurologic re-evaluation ranged from 4 to 7 years. Outcome was considered positive, satisfactory, or negative. Recurrence was defined as signs of a cervical myelopathy in dogs that initially improved or had stable disease postoperatively. RESULTS: All dogs had immediate postoperative improvement. Recurrence (4 months to 4 years postoperatively) occurred in 3 dogs that had multiple sites of compression. Long-term outcome was positive in 4 of 7 dogs. Postoperative imaging revealed subjective regression of bony proliferation at surgical sites in 2 of 4 dogs that improved clinically but morphometric data showed no change in canal measurements. An adjacent site lesion was confirmed in 1 dog. CONCLUSIONS: Distraction and stabilization with PMMA plugs and bone grafts is a safe surgical option for giant breed dogs with CSM with a single site of lateral or dorsolateral compression. Long-term recurrence was common among dogs with multiple sites of compression. Follow-up of 4 years or more among a larger population is indicated to fully assess implications of surgical intervention and determine recurrence rates.

Clinical progression of X-linked muscular dystrophy in two German Shorthaired Pointers.

CASE DESCRIPTION: 2 full-sibling male German Shorthaired Pointer (GSHP) puppies (dogs 1 and 2) with X-linked muscular dystrophy and deletion of the dystrophin gene (gene symbol, DMD) each had poor growth, skeletal muscle atrophy, pelvic limb weakness, episodic collapse, and episodes of coughing. CLINICAL FINDINGS: Initial examination revealed stunted growth, brachygnathism, trismus, and diffuse neuromuscular signs in each puppy; clinical signs were more severe in dog 2 than in dog 1. Immunohistochemical analysis revealed a lack of dystrophin protein in both dogs. During the next 3 years, each dog developed hyperinflation of the lungs, hypertrophy of the cervical musculature, and hypertrophy of the lateral head of the triceps brachii muscle. TREATMENT AND OUTCOME: Monitoring and supportive care were provided at follow-up visits during an approximately 7-year period. No other specific treatment was provided. Neuromuscular signs in both dogs remained stable after 3 years of age, with dog 2 consistently more severely affected than dog 1. The dogs had multiple episodes of aspiration pneumonia; dogs 1 and 2 were euthanatized at 84 and 93 months of age, respectively. CLINICAL RELEVANCE: The clinical course of disease in these dogs was monitored for a longer period than has been monitored in previous reports of dystrophin-deficient dogs. The clinical progression of muscular dystrophy in the 2 GSHPs was compared with that for other breeds and species with dystrophin-deficient conditions, and the potential basis for the phenotypic variation observed between these littermates, along with potential therapeutic ramifications for dogs and humans, was evaluated.

Recovery of pelvic limb function in dogs following acute intervertebral disc herniations.

Chondrodystrophoid breeds of dog are prone to explosive herniation of mineralized disc material into the thoracolumbar spinal canal. The resulting acute spinal cord injury may represent an excellent spontaneous model of acute traumatic spinal cord injury. The aims of this study were to quantify the recovery of dogs following acute disc herniations, to evaluate external factors that influence recovery, and to identify a group of dogs suitable for use in clinical trials on neuroprotective drugs. The gait of 88 dogs with thoracolumbar disc herniations was scored at the time of injury and 2, 4, and 12 weeks after surgical decompression. Dogs were placed into four groups dependent on the severity of presenting signs; dogs in group 1 had the most severe injury severity. Group 1 dogs showed a variable but incomplete recovery by 12 weeks. Dogs in groups 2 and 3 recovered uniformly but more completely, while dogs in group 4 made a rapid and excellent recovery and were deemed unsuitable for clinical trials. Combining dogs in groups 1, 2 and 3 produced a population of dogs with incomplete recovery by 12 weeks. Power analysis revealed that 87 such dogs would be needed per treatment group to detect a 20% change in function with a power of 95%. The number needed reduced drastically to 19 by eliminating dogs in group 1, but this produced less room for functional improvement. External factors did not appear to influence outcome. We conclude that dogs with spontaneous disc herniations provide a useful model of acute spinal cord injury for clinical trials.

Long-term functional outcome of dogs with severe injuries of the thoracolumbar spinal cord: 87 cases (1996-2001).

OBJECTIVE: To determine long-term (> 6 months) outcome of dogs with paraplegia and loss of hind limb deep pain perception (DPP) resulting from intervertebral disk herniation or trauma. DESIGN: Retrospective study. ANIMALS: 87 dogs. PROCEDURE: Outcome was determined as successful or unsuccessful. The association of neuroanatomic localization, breed, age, weight, sex, and (for dogs with intervertebral disk herniation) speed of onset of signs and duration of paraplegia prior to surgery with outcome was evaluated. Owners were contacted by telephone to identify long-term health problems. RESULTS: Nine of 17 dogs with traumatic injuries were treated, and 2 regained the ability to walk; none of the 17 dogs regained DPP. Sixty-four of 70 dogs with intervertebral disk herniation underwent surgery; 9 (14%) were euthanatized within 3 weeks after surgery (7 because of ascending myelomalacia), 37 (58%) regained DPP and the ability to walk, 7 (11%) regained the ability to walk without regaining DPP, and 11 (17%) remained paraplegic without DPP. Outcome was not associated with any of the factors evaluated, but speed of recovery of ambulation was significantly associated with body weight and age. Fifteen (41%) and 12 (32%) dogs that regained DPP had intermittent fecal and urinary incontinence, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that the prognosis for paraplegic dogs without DPP because of trauma was guarded, while dogs with disk herniation had a better chance of recovering motor function. A third of the dogs that recovered motor function had intermittent incontinence. Persistent loss of DPP did not preclude recovery of motor function, but such dogs remained incontinent.

Cytologic and histologic features of a poorly differentiated glioma in a dog.

A 5-year old female Boxer with a 1-week history of progressive paresis and paraplegia had a T10-13 subarachnoid filling defect on myelography. Exploratory hemilaminectomy revealed an intramedullary spinal cord tumor which was subsequently diagnosed as a poorly differentiated glioma, most likely an anaplastic ependymoma. The cytologic, histologic, and immunocytochemical staining characteristics of this neoplasm are described. Differential diagnoses, including primary and secondary tumors involving the central nervous system are discussed.