Diagnosis of erythema multiforme associated with thymoma in a dog and treated with thymectomy

A 7 yr old Labrador retriever initially presented for severe halitosis, mild ptylism, and depigmentation of the nasal planum. Erythema multiforme was diagnosed based on clinical signs and dermatopathology. Treatment was initiated but the condition did not resolve. Six months later, the dog was diagnosed with a mediastinal mass. Trucut biopsy was performed and histopathologic diagnosis was consistent with a thymoma. A median sternotomy was performed, the thymoma was excised, and the dog recovered well. Four months postoperatively, there were no longer any obvious erythema multiforme lesions and the skin condition was controlled without medication. Erythema multiforme may be a paraneoplastic disorder associated with thymoma in the dog, similar to thymoma-associated exfoliative dermatitis in the cat. Clinical signs of erythema multiforme may warrant performing thoracic radiographs or thoracic CT to rule out thymoma as an underlying cause.     

Olfactory esthesioneuroblastoma treated with orthovoltage radiotherapy in a dog

A 13-year-old neutered female mongrel dog presented with a 1-year history of stertorous respiration. On computed tomography examination, a mass was demonstrated in the nasal cavity. Open biopsy of the mass was performed and a diagnosis of olfactory esthesioneuroblastoma was made on histological examination. The dog was treated with orthovoltage x-ray radiation (total dose; 53 Gy given in 14 fractions over an 8 week period). Computed tomography after the twelfth irradiation revealed that tumour size had decreased. Although clinical signs were absent in the 4 months after irradiation, re-growth of the tumour was detected by radiographic evaluation and histological examination. The dog was again treated with orthovoltage x-ray radiation (total dose; 30 Gy given in three fractions over a 4-week period), however, tumour regrowth was again detected 3 months later. Clinical treatment of this tumour type has not been previously reported.     

Pericardial mesothelioma in a dog: long-term survival after pericardiectomy in combination with chemotherapy

A six-year-old male crossbred dog was presented with clinical signs of right-sided heart failure. Echocardiography demonstrated a pericardial effusion with cardiac tamponade, while pericardiocentesis and cytology did not reveal any evidence of malignancy. Pericardial drainage was performed twice over a period of three months to resolve haemodynamic impairment before a subtotal pericardiectomy was performed. Biopsy of parietal and visceral pericardium confirmed the diagnosis of pericardial mesothelioma. Intrathoracic cisplatin combined with intravenous doxorubicin were administered, although neutropenia, mild azotaemia and alopecia were noted as adverse reactions to these drugs. Intravenous cisplatin was repeated 45 days later after the signs of nephrotoxicity had resolved. The dog was still free of disease after 27 months. Intrathoracic chemotherapy after pericardiectomy and early diagnosis are recommended to improve prognosis, having achieved long-term survival in the present case.     

Surgical management of first caudal nerve root foraminal compression secondary to intervertebral disc disease in a Cocker Spaniel

A nine-year-old spayed female Cocker Spaniel was investigated for an eight week history of licking and rubbing at the tail base, dullness, and signs of pain on manipulation of the tail. Left-sided intraforaminal compression of the first caudal nerve root due to intervertebral disc disease was diagnosed by radiographic, computed tomography, and magnetic resonance imaging examinations. The dog was nonresponsive to conservative medical therapy. A decompressive left-sided first-second caudal (Cd1-Cd2) foraminotomy was performed. Postoperative computed tomography confirmed surgical decompression of the involved nerve root. At the one month follow-up examination there was marked improvement in clinical signs. At two months, clinical signs were completely resolved and there was not any evidence of recurrence twelve months after surgery. Intervertebral disc disease should be considered as a differential diagnosis in dogs with discomfort at the tail base or signs of pain on manipulation of the tail. Surgical decompression may be indicated for management of these cases. This is the first report of diagnosis and surgical management of caudal intervertebral disc disease by foraminotomy in the dog. Surgical decompression by foraminotomy may therefore be a treatment option for this condition.     

Balloon dilatation of nasopharyngeal stenosis in a dog

CASE DESCRIPTION: A dog was examined because of a 6-month history of upper airway stridor that began after postoperative regurgitation of gastric contents. CLINICAL FINDINGS: Constant stridor was evident during inspiration and expiration, although it was worse during inspiration. The stridor was no longer evident when the dog's mouth was manually held open. Computed tomography, rhinoscopy, and fluoroscopy were used to confirm a diagnosis of nasopharyngeal stenosis. TREATMENT AND OUTCOME: The dog was anesthetized, and balloon dilatation of the stenosis was performed. Prednisone was prescribed for 4 weeks after the procedure to decrease fibrous tissue formation. Although the dog was initially improved, signs recurred 3.5 weeks later, and balloon dilatation was repeated. This time, however, triamcinolone was injected into the area of stenosis at the end of the dilatation procedure. Two months later, although the dog did not have clinical signs of stridor, a third dilatation procedure was performed because mild stenosis was seen on follow-up computed tomographic images; again, triamcinolone was injected into the area of stenosis at the end of the dilatation procedure. Three and 6 months after the third dilatation procedure, the dog reportedly was clinically normal. CLINICAL RELEVANCE: Findings suggest that balloon dilatation may be an effective treatment for nasopharyngeal stenosis in dogs.     

Peliosis hepatis and hemoperitoneum in a dog with diphacinone intoxication

Objective: To describe the clinical course of a dog presented with peliosis hepatis and hemoperitoneum in concert with anticoagulant rodenticide intoxication.
Case summary: A 7.75-year-old spayed female Shetland Sheepdog presented with clinical signs consistent with hypovolemia, hemoperitoneum, and a history of bright green stool 3 days before the onset of clinical signs. Initial packed cell volume/total solids were consistent with acute hemorrhage. A coagulation profile showed prolongation in activated clotting time and prolongation of both prothrombin and activated partial thromboplastin time, suggesting abnormal coagulation. Abdominal hemorrhage persisted in the face of normalization of the hemodynamic status and coagulation profile, and treatment with Vitamin K₁. Abdominal ultrasound revealed multiple patchy hypoechoic areas throughout the caudate liver lobe. An exploratory laparotomy was performed 24 hours after presentation and revealed the caudate liver lobe as the source of the hemorrhage. Histopathologic examination of a specimen of the liver was consistent with peliosis hepatis. Toxicologic testing identified diphacinone levels in the blood consistent with anticoagulant rodenticide intoxication. Postoperative recovery was uneventful, and within 48 hours the dog was discharged. The dog returned to full function and a hepatic ultrasound performed 15 months postoperatively showed no significant abnormalities.
New or unique information provided: Exposure to anticoagulant rodenticides may be associated with the development of peliosis hepatis in dogs.     

Temporary regression of locally invasive polypoid rhinosinusitis in a dog after photodynamic therapy

A 5‐year‐old male cross‐breed dog with chronic rhinosinusitis was presented. Computed tomography (CT) revealed opacities consistent with soft tissue or fluid in the left nasal cavity and frontal sinus. A diagnosis of chronic rhinosinusitis with myxomatous polyps was based on the histology of biopsy samples, so prednisolone treatment was administered for 1 month. Although the clinical signs slightly improved, no changes were observed on the CT images. At 8 months after the initial presentation, the dog was treated with antivascular photodynamic therapy (PDT) using benzoporphyrin derivative monoacid ring A and, 11 days later, CT revealed remarkably decreased soft tissue opacity; the facial swelling and sneezing also resolved. Three additional sessions of PDT were performed at 114, 210, and 303 days after the first PDT because of recurrence of clinical signs. The disease was well controlled for approximately 10 months by antivascular PDT.     

Cerebellar cortical degeneration with selective granule cell loss in Bavarian mountain dogs

Three Bavarian mountain dogs aged between 18 and 20 months, not related to each other, were presented with chronic signs of cerebellar dysfunction. On sagittal T2-weighted magnetic resonance imaging brain images, the tentative diagnosis of cerebellar hypoplasia was established based on an enlarged cerebrospinal fluid space around the cerebellum and an increased cerebrospinal fluid signal between the folia. Post-mortem examination was performed in one dog and did show an overall reduction of cerebellar size. On histopathologic examination, a selective loss of cerebellar granule cells with sparing of Purkinje cells was evident. Therefore, the Bavarian mountain dog is a breed where cerebellar cortical degeneration caused by the rather exceptional selective granule cell loss can be seen as cause of chronic, slowly progressive cerebellar dysfunction starting at an age of several months.     

Signs consistent with syringobulbia may be detected in dogs undergoing MRI

Syringobulbia is a pathologic condition characterized by one or more fluid‐filled cavities within the brainstem. This retrospective case series describes observations in eight dogs with syringobulbia diagnosed during MRI. All dogs were adult, small‐breed dogs with concurrent syringomyelia and neurologic deficits localized to sites rostral to the spinal cord, which cannot be explained by syringomyelia (eg, six dogs had vestibular signs). On MRI, the fluid‐filled cavities had signal intensity characteristics like cerebrospinal fluid, were in the medulla oblongata, and were solitary in each dog. Initially, the shape of the cavity was a slit in five dogs and bulbous in two dogs. Magnetic resonance imaging was repeated in five dogs (6‐55 months of age). One dog had progression of syringobulbia from slit‐like to bulbous, and four dogs had unchanged slit‐like syringobulbia. One dog developed slit‐like syringobulbia after cranioplasty. A variety of medical and surgical treatments were performed with improvement of some but not all clinical signs. One dog died following surgery due to cardiopulmonary failure and the other seven dogs were alive at least 1 year after the initial diagnosis, which was the least time of follow‐up. One surviving dog developed a unilateral hypoglossal nerve deficit 2 months after the initial diagnosis and megaesophagus 14 months later. In conclusion, detecting a fluid‐filled cavity in the medulla oblongata consistent with syringobulbia is possible in dogs undergoing MRI. The cavity is likely acquired, slit‐like or bulbous, progressive, or static, and might be associated with breed size and neurologic signs localized to the medulla oblongata.     

Gastroesophageal intussusception in a young German shepherd dog

A gastro-oesophageal intussusception in a female, six-week-old German shepherd dog was treated surgically with success. The dog was presented with acute dyspnoea and signs of shock. After laparotomy, the herniated organs were reduced from the lumen of the oesophagus into the abdomen and an imbrication of the oesophageal hiatus, an appositional fundoplica-tion and a left-sided incisional fundopexy were performed. The dog made an uneventful recovery. Eighteen months after surgery the dog is still alive, with no clinical signs despite the persistent presence of megaoesophagus.     

Zygomatic sialocele secondary to infarction treated with sialoadenectomy in a dog

Zygomatic salivary gland disease is not commonly reported in dogs and there is a paucity of literature reporting salivary gland disease secondary to infarction in dogs. A 9-year-old German wirehaired pointer presented with left eye exophthalmos, 3rd eyelid elevation, negative retropulsion, and pain upon opening of the mouth. Computed tomography revealed a mass extending from the left zygomatic salivary gland, consistent with a sialocele. A left-sided zygomatic sialoadenectomy was performed successfully. Histopathologic diagnosis concluded zygomatic salivary gland infarction. The dog had no signs of recurrence 20 mo after surgery.Key clinical message:To the authors’ knowledge, this is the first case report with long-term outcome of a zygomatic sialocele secondary to salivary gland infarction in a dog treated by zygomatic sialoadenectomy via zygomatic osteotomy.     

RADIATION PNEUMONITIS IN THREE DOGS

Radiation pneumonitis developed within the radiation treatment field in three dogs with soft tissue sarcomas located on or adjacent to the thoracic wall. Radiographic signs compatible with a diagnosis of radiation pneumonitis developed from one (n = 2 dogs) to two (n = 1 dog) months after completion of therapy. The initial radiographic sign was an alveolar infiltrate in all three dogs. At subsequent examinations at variable time periods after treatment, radiographic findings included: bronchiectasis (n = 3 dogs), alveolar infiltrate (n = 2 dogs), decreased lung volume (n = 2 dogs), and unstructured interstitial opacification (n = 1 dog). Necropsy examination of one dog at fourteen months after the completion of radiotherapy showed evidence of pulmonary fibrosis within the irradiated lung. Necropsy examination of the second dog did not show any evidence of radiation induced changes. It is possible that histopathologic examination did not include irradiated lung. No clinical signs that could be attributed to the radiation pneumonitis were observed in any dog. It appears that approximately 25% of the lung can be safely irradiated to high doses, if indicated, in order to deliver an adequate dose of radiation to a primary tumor site.     

Panniculitis associated with pancreatitis in a cocker spaniel

A 13-year-old, male cocker spaniel presented with a history of inappetence, depression and reluctance to stand. The dog had multiple, ulcerated skin lesions which were diagnosed as panniculitis by histopathology. A diagnosis of pancreatitis was made on the basis of markedly elevated serum lipase concentrations, abdominal ultrasonography which showed an abnormal lobulated area of hypoechoic tissue in the body and right lobe of the pancreas, and a fine needle biopsy from this area which revealed large numbers of degenerate neutrophils. After treatment with antibiotics and prednisolone, the dog made a full clinical recovery and was free of clinical signs for four months. The dog was euthanased five months later and postmortem examination revealed chronic, active pancreatitis and a pancreatic adenoma. This is the first report of antemortem diagnosis of pancreatitis and panniculitis in a dog.     

Emergency presentations of 4 dogs with suspected neurologic toxoplasmosis

Objective: To review the signalment, clinical signs, abnormal laboratory data, therapeutics, and response to therapy of dogs with clinical signs consistent with toxoplasmosis infection. Series summary: A retrospective review was performed on the records of 4 dogs presented to the Animal Emergency Center between January 1998 and February 2000 exhibiting neurologic signs and having elevated titers for Toxoplasma gondii. A tentative diagnosis of toxoplasmosis was based upon one of the following criteria: (1) a serial 4‐fold or greater change in serum T. gondii IgG titers; 2) serially decreasing serum T. gondii IgM titers with concurrent increasing serum T. gondii IgG titers; or 3) positive cerebrospinal fluid (CSF) T. gondii titers. In addition, inclusion of cases was limited to dogs that showed improvement of neurologic signs following treatment with antiprotozoal drugs. Trimethoprim–sulfamethoxazole treatment was associated with successful elimination of clinical signs in all of the dogs. Two of the dogs developed side effects potentially attributed to the trimethoprim–sulfamethoxazole (TMS), and antiprotozoal treatment was continued using clindamycin. Unique information presented: Toxoplasmosis is an important differential diagnosis in any dog that presents as an emergency with central or peripheral neurologic signs. Affected dogs need not be immunocompromised for clinical signs of toxoplasmosis to occur. Appropriate treatment with TMS or clindamycin can lead to resolution of clinical signs.     

Migrating grass awn within the intraconal part of the retrobulbar space in a dog

A 1.5-year-old MC Cardigan Welsh Corgi was presented for a right oral fistula associated with left tonsil enlargement that responded to medical treatment. A first computed tomography scan was performed and showed no signs of a foreign body. Medical treatment was continued for 2 additional weeks and the dog was free of clinical signs for 3 months. The dog was presented again for a 3-day history of anorexia and marked pain when opening the jaw. The repeat computed tomography scan revealed a migrating foreign body near the optic canal of the right eye, and surgical exploration confirmed that it was trapped within the intraconal part of the retrobulbar space, abutting the optic nerve. The foreign body was surgically removed through an osteotomy of the zygomatic bone. The dog fully recovered with no vision loss. Based on the literature search, this is the first published report describing a migrating grass awn located in the intraconal part of the retrobulbar space, abutting the optic nerve.     

Rectal ganglioneuroma in a dog

An 18-month-old, spayed female Australian terrier cross was presented with a 10-month history of chronic large bowel diarrhea. Ulceration and two proliferative masses in the rectum were seen on colonoscopy. Surgical resection was performed to remove the masses, and the dog recovered without complications related to surgery. Histopathology was consistent with the diagnosis of ganglioneuroma. The dog had no clinical signs of disease within three months of surgery and was completely normal 2.5 years after diagnosis. This is the first report providing follow-up and successful outcome of a ganglioneuroma in the gastrointestinal tract of a dog.     

Mitotane (o, DDD) resistance in a dog with pituitary-dependent hyperadrenocorticism and phaeochromocytoma

A dog was presented with a 2 year history of polyuria and polydipsia due to pituitary-dependent hyperadrenocorticism. A low-dose dexamethasone suppression test and measurement of plasma ACTH concentration confirmed the diagnosis. Treatment was instituted with mitotane at 44 mg/kg/day and then 88 mg/kg/d without complete resolution of signs. The dog collapsed with signs consistent with liver disease and was euthanased. Necropsy revealed a phaeochromocytoma of the left adrenal medulla with extensive metastases to the liver. A chromophobe adenoma of the pars intermedia of the pituitary was found.     

PROBABLE TRIGEMINAL NERVE SCHWANNOMA IN A DOG

A 7-year-old male Husky dog developed atrophy of the right masseter muscle and pruritis of the right side of the face. A myogenic origin was excluded using muscular biopsy. Electrophysiologically, there was involvement of the motor and sensory fibers of the trigeminal nerve, suggesting a lesion located between the brainstem and the trigeminal ganglion. On MRI examination, a nodular mass was detected in the right caudal fossa. This mass was characterized by intense enhancement after injection of contrast medium. Because of the progressive clinical signs, electrophysiology, and MRI results, a presumptive diagnosis of a trigeminal nerve schwannoma was made. The animal's condition improved slightly with corticosteroids. The dog underwent euthanasia 3 months after initial presentation. Necropsy was not performed.     

Tick-borne encephalitis virus as a possible cause of optic neuritis in a dog

A 3-year-old spayed female Siberian Husky was presented due to acute vision loss. Examination revealed bilateral optic neuritis and lymphocytic meningoencephalitis. The serum (1:800) and cerebrospinal fluid (CSF; 1:200) immunoglobulin (Ig)G titers for tick-borne encephalitis virus (TBEV) were elevated as were the serum IgG titer for Anaplasma phagocytophilum (1:640) and serum IgM titer for Toxoplasma gondii (1:20). Intracytoplasmic inclusion bodies such as ehrlichial or anaplasmal morulae were not observed in the CSF or blood smear. The dog was treated with methylprednisone and doxycycline. The left eye regained vision; the right eye remained blind. Anti-inflammatory therapy was stopped on day 18 after diagnosis. Four days later the dog showed evidence of hyperesthesia in the cervical region. Analysis of CSF showed no abnormalities and CSF IgG titers for TBEV and A. phagocytophilum were negative. Funduscopic evidence of active papillitis was absent on day 22 in the left eye and on day 86 in the right eye. On day 243, the dog was presented again with lethargy, ataxia, disorientation and temporary head tilt. The IgG titer for TBEV was again elevated in the CSF (1:800) and in serum (1:400). After interpretation of all findings, we assume that meningoencephalitis and optic neuritis in this patient was caused by TBEV and associated immune-mediated inflammation. In endemic areas, TBEV should be considered as cause of optic neuritis in dogs.     

Idiopathic primary chylopericardium in a dog

CASE DESCRIPTION: A 7-year-old spayed female Labrador Retriever was evaluated because of pericardial effusion. CLINICAL FINDINGS: The dog had a history of decreased appetite and exercise intolerance of 3 days' duration. Thoracic radiography performed by the referring veterinarian revealed a large cardiac silhouette. Heart sounds were muffled. Echocardiographic findings were indicative of severe pericardial effusion with cardiac tamponade; no pleural effusion was identified. Pericardiocentesis yielded a considerable amount of chylous fluid. A diagnosis of chylopericardium in the absence of pleural effusion was made. TREATMENT AND OUTCOME: Conservative management was not effective, and subtotal pericardectomy and thoracic duct ligation were recommended. Surgery was postponed by the owners for 25 days, at which time the dog had both chylopericardium and chylothorax. The dog underwent subtotal pericardectomy and thoracic duct ligation; to delineate the thoracic duct, intraoperative lymphangiography was performed by injection of a radiopaque contrast agent directly into a mesenteric lymph node and subsequent injection of methylene blue solution into another mesenteric lymph node. Surgical treatment resulted in complete resolution of the clinical signs and pleural effusion. CLINICAL RELEVANCE: To the authors' knowledge, this is the first report of the development of chylopericardium prior to development of chylothorax in a dog. Treatment with thoracic duct ligation and pericardectomy resulted in complete resolution of the effusion and clinical signs.