Our Interesting Cases section present some of the more unusual cases that the veterinary specialists at the Mississauga Oakville Veterinary Emergency Hospital have encountered.
Each case will give you the pet's presentation and associated images. When you are ready, click the Show Diagnosis button to see the diagnosis / treatment with an explanation.
A 3 year-old Golden Retriever presented with an acute RH lameness. Pelvic/RH radiographs were unremarkable and an ultrasound was performed.
Diagnosis
Torn right Achilles tendon
Discussion
The Achilles tendon was repaired and a hybrid external fixation was used to maintain tarsal extension. Immediately post surgery the patient was given daily low level light laser therapy (LLLT) treatments for 5 days along the incision and around the area of the repair to decrease inflammation and aid in healing. The external fixator was removed after a period of 3 months and the patient was immediately referred for rehabilitation.
Upon assessment in rehab the patient was completely non-weight bearing on the right hind limb. There was considerable scar tissue around the achilles, mild to moderate atrophy of the hindlimb musculature and significantly decreased tarsal flexion.
Treatments in rehab have included:
manual mobilizations of the talocrural joint to encourage tarsal flexion
cross-friction massage and myofascial release techniques to break up adhesions and reorient tissue connective tissue fibres
continued LLLT
stretching of the right hind limb
underwater treadmill, initially at slow speeds, to encourage weight bearing on the affected limb
extensive home exercise program to strengthen, mobilize and stretch
After the patient’s initial treatment, weight bearing increased dramatically. Over the course of 3 months of in-house and at home treatment the patient is fully weight bearing and there is negligible atrophy of the hindlimb musculature. Talocrural flexion has dramatically improved and is well within a functional range.
A 3.5 year-old MN Giant Schnauzer presented with a diffuse alopecic pustular dermatitis (Figure 1). The dog was previously diagnosed with immune-mediated hemolytic anemia, and is currently receiving prednisone, azathioprine and cyclosporine. On it's skin scraping you see something unexpected (Figure 2).
Diagnosis
Cutaneous toxoplasmosis
Discussion
Cutaneous protozoosis was diagnosed on this skin scraping cytology. Postmortem examination revealed additional protozoa within cutaneous, cardiac, pancreatic, and pulmonary tissues. Further testing of the protozoa indicated that it divided by endodyogeny, had the morphology of Toxoplasma gondii (T. gondii) tachyzoites, and stained positively with T. gondii polyclonal antibodies but not with antibodies to Neospora caninum or Sarcocystis neurona, confirming the diagnosis of cutaneous and disseminated toxoplasmosis.
Immune-mediated hemolytic anemia had been diagnosed 45 days previously. At the time of presentation, the dog was receiving prednisone, azathioprine, and cyclosporine. Immunosuppression may have predisposed this dog to disseminated toxoplasmosis, which is an uncommon presentation of toxoplasmosis.
Reference
This case was published in the Journal of the American Animal Hospital Association, 2005;41:198-202 (pdf copy).
A 7 year-old FS Miniature Poodle cross presented for a 2 week history of vomiting, lethargy, weight loss and decreased appetite. Abdominal ultrasound demonstrated several large masses in the omentum that were consistent with marked mesenteric lymphadenopathy and multifocal hypoechoic nodules throughout the spleen. A radiopaque mediastinal mass was noted on thoracic radiographs (Figure 1). An unusual result was seen on cytology from fine needle aspirates of the mesenteric lymph nodes and spleen. (Figure 2).
Diagnosis
Phialosimplex caninus
Discussion
An atypical fungal infection with both fungal hyphae and budding yeast was diagnosed on cytology from the mesenteric lymph nodes and spleen. A sample from fine needle aspirate of an enlarged prescapular lymph node was submitted for fungal culture. The sample was processed over the next 2 months at Public Health due to concern for personnel safety with exposure. The dog was placed on itraconazole (5 mg/kg/day) while awaiting culture results. The culture results and typing were consistent with Phialosimplex caninus, which is a newly described anamorphic genus of fungi that is closely related to Sagenomella, Aspergillus and Penicillium. Infection with P. caninus has been recognized in a small number of dogs. Infection has been most associated with marked lymphadenopathy or mycotic discospondylitis, but will typically progress to involve numerous sites. The route of exposure had thought to be through wounds in the skin or mucosa. The prognosis has been considered poor in the small number of cases reported. In this case, there was no history of travel, skin wounds or immunosuppression, and the source of exposure was uncertain.
On recheck examination 3 months after presentation, the dog was clinically improved with no vomiting, a good appetite, weight gain and normal energy level. There was minimal change in the appearance of the mediastinal mass, mesenteric lymph nodes or spleen on thoracic radiographs and abdominal ultrasound respectively. A higher dose of itraconazole (10 mg/kg/day) was recommended. Follow-up imaging was planned in another 2-3 months.
Reference
Sigler L, Sutton DA, Gibas CF, Summerbell RC, Noel RK, Iwen PC. Phialosimplex, a new anamorphic genus associated with infections in dogs and having phylogenetic affinity to the Trichocomaceae. Med Mycol. 2010 Mar; 48(2): 335-45
Gene J, Blanco JL, Cano J, Garcia ME, Guarro J. New filamentous fungus Sagenomella chlamydospora responsible for a disseminated infection in a dog. J Clin Microbiol. 2003; 41(4): 1722-25.
A 5 month old F Labrador-cross presented with a waxing history of lethargy and marked shifting forelimb lameness. On physical exam, the puppy was febrile (40.1C) and lethargic. Although she was not lame on any particular limb at presentation, she was reluctant to stand and ambulate. She demonstrated discomfort on palpation of the distal radii and tibiae. There was also firm swelling in these locations, which were warm to the touch. Otherwise she had excellent ROM in all her joints; there was no crepitus, effusion, swelling, pain or instabilities noted elsewhere on the limbs. Radiographs of the distal radii were performed (Figures 1 and 2; right distal radius).
Diagnosis
Hypertrophic Osteodystrophy (HOD)
Discussion
HOD is a condition of young, typically large and giant breed dogs (Great Danes, Labradors, Irish Setters and Boxers). The grossly observable swellings of the distal radii and tibiae are characteristic for this condition. The etiology is unknown but has historically been associated with a vitamin C deficiency. This is no longer considered to be the case, but more recent studies indicated that it may be linked to the distemper virus.
Radiographically there is typically a thin radiolucent line in the distal metaphysis of the affected bones. The radiolucent line becomes radiopaque with time. Extraperiosteal cuffing can also be appreciated in some cases. Treatment is symptomatic with NSAIDs and narcotics, as necessary. In severe cases, intravenous fluid administration is indicated. In most cases the clinical signs will disappear in 7-10 days, although relapse is possible. In severe cases, secondary angular limb deformities may occur.
A 3.5 year old female spayed Boxer presented for evaluation of acute onset of severe head and neck pain while out for a walk. Proprioceptive positioning was delayed on the right side, but hopping was adequate. An MRI was performed (Figure 1).
Additional History
The Boxer initially presented for evaluation of pain, lethargy, and stiffness. Three months prior to presentation her owner had noticed her slowing down and she had been panting and sleeping more than usual. The patient had previously responded intermittently to Meloxicam 28kg dose PO q24h, Methocarbamol 500mg 1tab PO q12 and Tramadol 150mg tab ½ tab PO q8h.
Neurological Examination
Mental Status: BAR
Cranial Nerves: NAF
Gait and Posture: Ambulates well without assistance. Proprioceptive positioning delayed on right side, but hopping is adequate
Spinal Reflexes: Right thoracic limb flexor is harder to elicit
Back Pain: NAF, good cervical range of motion
MRI
In the lateral right hemisphere, affecting the frontal, parietal and temporal lobes, there is a well-demarcated 2x2x2.5cm lesion with patchy enhancement on post gadolinium T1 weighted images. The mass abuts the calvarial wall and displaces brain parenchyma medially with leftward deviation of the falx cerebri, the mass does not have broad-based contact with the calvarium, suggestive of intra-axial rather than extra-axial origin.
Conclusions: mass lesion in right cerebral hemisphere, suspicious for glioma, with surrounding vasogenic edema.
Surgical Biopsy of Brain
Fleshy spindle cells which form whorls. Some of the whorls surround vascular structures giving the appearance of a hemangiopericytoma. The tumor cells have oval to elongated nuclei often with a distinct nucleolus. Cell margins are indistinct. The mitotic rate is low (1-3 mitoses PHPF). There is a marked, mainly lymphocytic, inflammatory reaction at the margins of the tumor. Hemorrhage and fibrino-cellullar exudate are also evident at the margins.
Diagnosis
Angioblastic meningioma
Follow Up
6 months later after radiation therapy (cyber knife): There is a resolution of mass effect and right cerebral lesion identified on previous MRI (Figure 2). No pathological contrast enhancement was identified after gadolinium injection.
Additional Figures
Figure 2: MRI: Brain 6 months post radiation therapy
Treatment
The patient was referred to Yonkers, New York for a type of radiation treatment called Cyberknife therapy. This type of advanced treatment uses both MRI and CT scan to precisely target the brain tumor with little radiation delivered to the surrounding normal structures. This precision allows high doses of radiation to be delivered in just one to three treatments.
Discussion
Definitive or curative intent treatments for brain tumors in dogs include surgery and/or radiation therapy. Best results are seen when surgery is followed by radiation therapy, since wide surgical margins are not possible in this location and microscopic disease is often left behind leading to eventual local recurrence and a median reported survival time of 7-12 months. Radiation therapy is either delivered in small daily (Monday through Friday) doses over 4 weeks (fractionated radiotherapy) or as 1-3 large doses via a very precise machine that uses both MRI and CT scan to target the tumor (gamma knife, cyberknife or stereotactic radiosurgery). Fractionated radiation therapy is available at OVC via a cobalt unit or in the U.S. with more advanced linear accelerators. The more advanced machinery for stereotactic or cyberknife treatment is only available at some locations in the US, the closest being a private practice in Yonkers, NY. With radiation therapy, either as the sole treatment or in conjunction with surgical debulking, median survival times ranging from 1 to 3 years are reported.
The palliative benefits of corticosteroids and anti-seizure drugs can benefit dogs with brain tumors. These medications are not affecting the actual tumor cells, but are decreasing peri-tumoral edema and inflammation (steroids) and decreasing the seizure threshold. They do not affect the growth of the tumor, which eventually could lead to more seizures or development of other neurologic clinical signs. The median survival times reported with these medications ranges from 1 to 4 months. Chemotherapy is an area of interest for prolonging survival in dogs receiving palliative care or as an adjuvant to surgery or radiation therapy. The chemotherapy may act to stabilize the tumor and prevent or slow the growth, therefore delaying the time to when the tumor causes quality-of-life affecting symptoms.
Hydroxyurea is one chemotherapy drug that has been investigated in both human and canine meningioma. It tends to be well tolerated by most dogs. Potential side effects include gastrointestinal upset, anemia, immunosuppression, methemoglobinemia, hair loss, and sloughing of the toenails. Therefore, complete blood counts are recommended 2 weeks after starting and then monthly after that. An abstract has been presented which showed a benefit in overall survival in canine meningioma patients receiving hydroxyurea compared to symptomatic therapy (steroids and anti-seizure medications) alone, with a median survival time of 7-8 months.
Jasmine is a 5 year old, FS, Himalayan cross that presented with severe pinnal and facial crusting dermatitis (Figure 1) and purulent paronychia (Figure 2) unresponsive to antibiotic therapy. The owners reported that Jasmine was lethargic and partially inappetant. Impression cytology from beneath a newly formed crust was performed (Figure 3).
Diagnosis
Pemphigus foliaceus
Discussion
Pemphigus foliaceus is the most common autoimmune dermatitis in cats. Age of onset is highly variable but the highest incidence occurs between 2-5 years of age. Lesions in cats initially appear on the head including the pinna and paws, especially at claw folds. The classic lesion is a pustular eruption. Pustules are often fragile and therefore transient. Cats typically present with crusts or erosions on the skin and purulent paronychia affecting multiple digits. An impression smear showing neutrophils and acantholytic keratinocytes suggests pemphigus foliaceus, however skin biopsies of pustules or newly formed crusts are required to confirm the diagnosis.
Treatment
Immunosuppressant doses of corticosteroids (prednisolone or dexamethasone) in combination with antibiotics for secondary bacterial infection are the initial therapy. Combination immunomodulatory therapy with steroids and chlorambucil may be required in recalcitrant cases. Therapy is typically life long but some feline patients can be slowly weaned off medications and remain in remission.
A 7 year old spayed female Lab presented for evaluation of a 2-week history of coughing. She had a history of enucleation 2 month prior for an ocular mass that was diagnosed as an iridiociliary carcinoma. Radiographs revealed multifocal pulmonary masses (figure 1) and cytology was obtained by ultrasound-guided fine needle aspiration (figure 2).
Diagnosis
Metastatic melanoma
Discussion
Cytology was diagnostic for metastatic melanoma. The most common site for malignant melanoma in the dog is the oral cavity. Complete oral examination did not reveal any lesions, and physical examination did not reveal any suspicious cutaneous lesions. Review of the histopathology report from the enucleated eye showed that the diagnosis was based on very few cells and that the majority of the tumor was found to be necrotic. The most likely explanation is that the eye mass was a malignant melanoma that was not diagnosed due to the high degree of tumor necrosis.
The majority of canine intraocular melanomas arise from the iris or ciliary body and are classified as benign. Tumors classified as malignant on histopathology have a modest metastatic rate reported at ~25% in one study. When metastasis does develop, it is typically only a few months after surgery and the prognosis is guarded. Radiographs had not been taken at the time of enucleation, because the histopathology came back with a diagnosis of iridiociliary carcinoma, and the metastatic risk was considered very low. Treatment options for metastatic melanoma include immunotherapy with the Canine Melanoma Vaccine, chemotherapy, and antiangiogenic therapy.
A 6 year old female spayed Great Dane presented for lethargy, fever, anemia and elevated total bilirubin. She has a previously diagnosed pancytopenia three months prior that resolved without therapy. A complete blood count with pathologists review found this very interesting anomaly in the red blood cells (Figure 1).
Diagnosis
Babesia gibsoni
Discussion
Canine babesiosis is a tick borne disease (Figure 2) caused by a protozoan blood parasite. Both Babesia canis (Figure 3) and Babesia gibsoni (Figure 4) are found throughout the United States but are very rarely found in Canada. This patient was a rescue dog from the United States where the infection was likely acquired.
Grey hounds and pit bulls have a higher incidence of disease than other breeds of dogs. Babesia infections cause a wide variety of signs including anemia, splenomegaly, icterus, weight loss and fever.
Diagnosis is confirmed with blood smears and PCR (DNA testing) although there are several other tests available.
Treatment involves medications for a 10 day period but patients that are immunocompromised or have had a splenectomy are at increased risk for recurrence. To date, no drugs have been shown to eliminate B. gibsoni infections from dogs. Typically therapy has involved imidocarb diproprionate and/or diminazine aceturate. Recently, a combination of atovaquone and azithromycin was shown to either eliminate B. gibsoni infections or suppress the parasitemia below the limit of detection in the majority of treated dogs, and therefore shows promise.
Additional Figures
Figure 2: The brown dog tick can transmit Babesia gibsoni
A 1.5 year old male neutered Shih Tzu x Poodle mixed breed dog, presented to the neurology service for a cluster of 5-6 seizures within a 12 hour period before presentation. The seizures were increasingly frequent, with one episode every 30 min. Episodes lasted 30 sec each, were generalized tonic/clonic, with mouth foaming and urination. An MRI was performed.
Neurological Examination
Mental Status: BAR
Cranial Nerves:
Pupillary size normal and symmetrical
PLR - responsive OU (direct and indirect)
Physiological nystagmus - present OU
Resting/positional nystagmus - absent OU
Menace response - OS: decreased to absent. OD: present
Palpebral reflex - present OU
Nasal septum response - present bilaterally
Facial symmetry - normal and symmetrical
Head tilt - none
Gait and Posture:
No gait deficits
Proprioceptive positioning - Right forelimb (+2); left forelimb (+1); Right hindlimb (+2); Left hindlimb (+1)
Spinal Reflexes: Adequate
Back Pain: None elicited
Cerebrospinal Fluid
No etiological agents or atypical cells were identified. Interpretation: No cytological abnormalities.
Magnetic Resonance Imaging
See Figures.
Diagnosis
Quadrigeminal cyst (intracranial arachnoid cyst) and seizures
Magnetic Resonance Imaging
Adjacent to the third ventricle and continuously towards the fourth ventricle, there is an accumulation of fluid within the quadrigeminal cisterna. The fluid is hyperintense on T2-weight images. The fluid signal nulls on FLAIR images indicating accumulation of cerebrospinal fluid.
Conclusions
Quadrigeminal cyst. No other parenchymal abnormalities or contrast enhancing lesions.
Treatment
Levetiracetam
Omeprazole
Phenobarbital
Discussion
Intracranial arachnoid cyst (IAC), also known as quadrigeminal cyst, is a developmental brain disorder in which cerebrospinal fluid (CSF) accumulates in an additional pocket surrounded by arachnoid membrane, that forms during embryogenesis. It is a rare condition and the majority of dogs affected are small breed, brachycephalic breeds, the Shih Tzu being one of them. The most common clinical signs are seizures and cerebellovestibular dysfunction. Neck pain has also been reported. In humans, IACs are usually an incidental finding and literature suggests that may also be the same in dogs. As such, when IAC is found on imaging, other conditions that may cause similar clinical signs to the presenting complaint should be ruled out. In this particular case, neoplasia and meningoencephalitis were ruled out based on imaging and cerebrospinal fluid analysis.
For dogs that suffer from symptomatic IAC, medical therapy is usually successful initially but the response is often temporary. Successful surgical fenestration and cystoperitoneal shunting procedures have been described in literature for IAC dogs.
Seizures in this patient could be due to primary epilepsy or from the IAC. It would be difficult to differentiate the two scenarios with certainty. Response to therapy may provide some indication in the future.
A combination of antiepileptic drugs were used to control the seizures (Levetiracetam and Phenobarbital). In addition, Omeprazole, a proton pump inhibitor, was used to reduce production of cerebrospinal fluid to relieve symptomatic IAC.
Figures
Figures 1 A and B: MRI: Transverse and Fig 1B: Sagittal T2-weighted images of intracranial cystic structure (orange arrow). Cystic structure is seen as a dilated fluid-filled sac extending caudodorsally from the ventricular cisterna. The fluid is isointense with ventricular cerebrospinal fluid
Figure 2: MRI: Transverse fluid attenuated inversion recovery sequence. Fluid in the cystic structure is hypointense to brain parenchyma and isointense to cerebrospinal fluid, indicating that the fluid in the cyst is cerebrospinal fluid
