Diagnostic and public health investigation of Mycobacterium tuberculosis infection in a dog in Ontario,Canada

A 4-y-old, female mixed-breed dog was presented to the Ontario Veterinary College for further evaluation of multiple pulmonary and hepatic masses, intrathoracic lymphadenitis, and recent development of a pyogranulomatous pleural effusion. Along with other comprehensive tests, a thoracic lymph node biopsy was performed, and Mycobacterium tuberculosis complex infection was confirmed by real-time PCR. The dog’s condition declined post-operatively, and euthanasia was elected. Postmortem examination confirmed severe granulomatous pneumonia, hepatitis, intrathoracic and intraabdominal lymphadenitis, omentitis, and nephritis. Line-probe assays performed on samples collected postmortem confirmed the species as M. tuberculosis. 24-loci MIRU-VNTR genotyping, spoligotyping, and whole-genome sequencing revealed relations to known human isolates, but no epidemiologic link to these cases was investigated. Given the concern for potential human exposure during this animal’s disease course, a public health investigation was initiated; 45 individuals were tested for M. tuberculosis exposure, and no subsequent human infections related to this animal were identified. Our case highlights the need for more readily available, minimally invasive testing for the diagnosis of canine mycobacteriosis, and highlights the ability of canid species to act as potential contributors to the epidemiology of M. tuberculosis infections.     

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.     

Combined corneal lipid and calcium degeneration in a dog with hyperadrenocorticism: a case report

Corneal degeneration may occur with a deposition of lipids or calcium, or both. Calcareous and lipid degeneration may be either primary or secondary, associated with systemic diseases such as primary hyperlipidemia, hyperlipidemia associated with hyperadrenocorticism, and hypothyroidism. The authors report a case of bilateral corneal lipid and calcium degeneration in a 7-year-old female Poodle with hyperadrenocorticism. The condition worsened with Lysodren therapy but responded to surgical excision.     

Pulmonary Mycobacterium bovis infection in a dog

dAim: To describe the clinical course of a dog infected with Mycobacterium bovis causing a granulomatous pneumonia.

dClinical findings: The dog initially presented with a persistent cough, inappetence and weight loss. Clinical findings included a fever, dyspnoea and tachypnoea, with haematological evidence of a mild neutrophilia and hypoalbuminaemia. Radiographs of the chest demonstrated a concomitant pneumothorax, pleural effusion, and a consolidated area within the left caudal lung lobe. An exploratory thoracotomy revealed this to be a ruptured granulomatous lesion. Subsequent histopathological, microbiological and genetic studies identified M. bovis as the causal agent.

dClinical significance: Mycobacterium bovis infections should be included in the differential diagnosis of pulmonary disease and pleural effusions in dogs living in regions of New Zealand known to have a high incidence of mycobacterial infection in wildlife and farm animals.     

Serum acute phase protein concentrations in dogs with hyperadrenocorticism with and without concurrent inflammatory conditions

Background: Acute phase proteins (APPs) are promising markers of inflammation in dogs, because they are more sensitive than WBC counts in detecting clinical and subclinical inflammation. Endogenous corticosteroids can mask an acute phase response and make it more difficult to identify underlying inflammatory disease. Objective: The purpose of this study was to evaluate the acute phase protein response in dogs with spontaneous hyperadrenocorticism (HAC) with and without concurrent inflammatory conditions. Methods: Serum concentrations of C‐reactive protein (CRP), haptoglobin (Hp), fibrinogen, and albumin were measured in 44 healthy adult dogs and 39 dogs with HAC; the HAC group was further divided into dogs with and without concurrent infection/inflammation. A fourth group of dogs with severe sepsis and without HAC was compared with the dogs with HAC and severe sepsis. Results: Dogs with uncomplicated HAC had significantly higher Hp and fibrinogen concentrations compared with healthy control dogs (P<.001). Dogs with HAC and severe inflammatory disease also had significantly higher CRP and lower albumin concentrations than control dogs and dogs with HAC without concurrent inflammation. Dogs with sepsis but without HAC had significantly higher CRP concentrations than dogs with HAC and sepsis. Conclusions: Dogs with HAC had increases in the moderate APPs (Hp and fibrinogen), and no significant changes in CRP and albumin compared with healthy dogs. Although concurrent HAC appeared to blunt the CRP response in dogs with sepsis, increased serum CRP concentration in dogs with HAC is likely indicative of severe concurrent inflammation.     

Pneumothorax secondary to pulmonary thromboembolism in a dog

Objective – To describe a case of spontaneous pneumothorax secondary to pulmonary thromboembolism possibly associated with pituitary dependent hyperadrenocorticism.
Case Summary – A 7-year-old spayed female Collie weighing 26 kg was referred for evaluation of spontaneous pneumothorax. An exploratory thoracotomy was performed and revealed 2 lung lobes to be diffusely hemorrhagic and they were resected. Histologic examination of multiple sections documented diffuse thromboembolism. A 2–3 cm thrombus was visualized distal to the bifurcation of the pulmonary artery during an echocardiographic examination postoperatively. The dog was discharged to the owner after recovery from surgery. The thrombus had resolved at the 4-week recheck examination. Diagnosis of pituitary dependent hyperadrenocorticism was confirmed based on follow-up endocrine testing.
New or Unique Information Provided – This is the first report of pulmonary thromboembolism causing spontaneous pneumothorax in the dog.     

Acute bronchopneumonia associated with Mycobacterium fortuitum infection in a dog

Mycobacterium fortuitum was isolated in a sample of bronchial fluid collected by transtracheal aspiration from a 1-year-old Corgi dog with a productive cough of 10 days' duration and with radiographic and cytological features of acute suppurative bronchopneumonia. The dog responded favourably to intravenous gentamicin and cephalexin for three days and a six week course of oral ciprofloxacin. Saprophytic mycobacterial pneumonia should be considered in cases of severe pulmonary consolidation in young dogs.     

Mycobacterium tuberculosis infection in a dog from Africa

A 4-year-old male Boxer dog with a history of vomiting, diarrhea, and weight loss moved from West Africa to Lyon, France, where it was further evaluated. Radiographs revealed pleural effusion and enlargement of tracheobronchial lymph nodes and liver. Cytologic examination of the pleural effusion and a fine needle aspirate specimen of the liver showed mixed mononuclear inflammation with nonstaining rod structures within epithelioid histiocytes. At necropsy, the main gross pathologic findings were exudative pleuritis, nodular hepatitis, and infarcts and caseous nodules in the kidneys. The main histologic lesions were granulomatous hepatitis, granulomatous pneumonia, fibrinous leukocytic pleuritis, necrotic and fibro-calcified granulomatous lymphadenitis, and granulomatous nephritis. A Ziehl-Neelsen stain applied to both cytologic and histologic samples was positive for acid-fast bacilli. Bacterial culture of the pleural fluid was positive for Mycobacterium tuberculosis. Cytology is a valuable tool in the diagnosis of this important zoonotic disease.     

Disseminated Mycobacterium avium infection in a dog with chronic diarrhoea

A 3-year-old Maltese-cross dog presented with a 4-month history of chronic diarrhoea and inappetence. Poorly regenerative anaemia, leukocytosis and hypoproteinaemia were evident on several occasions. Biopsies of stomach, duodenum and colon revealed marked infiltration of mucosae by macrophages containing many acid-fast bacilli. Similar organisms were numerous in a faecal smear. Melaena, hematochezia and severe abdominal pain developed and were unresponsive to therapy. Following euthanasia and necropsy, histiocytic cells containing acid-fast bacilli were found throughout the gastrointestinal tract, mesenteric and peripheral lymph nodes, spleen, liver, kidney and lungs. The organism was identified as Mycobacterium avium by bacterial culture and polymerase chain reaction testing.     

Systemic infection of Mycobacterium avium subspecies hominissuis and fungus in a pet dog

A 3-year-old neutered female poodle with a long history of dermatophytic skin disease was presented with lethargy, anorexia and progressive weight loss. Abdominal ultrasonography revealed markedly enlarged mesenteric lymph nodes and multiple hypoechoic foci in the spleen. Cytology of the mesenteric lymph nodes and spleen showed granulomatous inflammation with fungal organisms and negatively stained intracytoplasmic bacterial rods consistent with Mycobacteria spp. Based on culture, multiplex polymerase chain reaction and sequence analysis, the bacterium was identified as Mycobacterium avium subspecies hominissuis. Despite treatment with antibiotics, the dog’s condition deteriorated, and it died approximately 3 weeks after first presentation.     

Paraganglioma,pituitary adenoma,and osteosarcoma in a dog

An 11‐year‐old neutered male Alaskan Malamute mixed‐breed dog was presented with a complaint of polyuria/polydipsia (PU/PD), weight loss, tachypnea, regurgitation, and a previous history of nontreated osteosarcoma of the right distal radius, diagnosed 21 months prior. On physical examination, an abdominal mass was palpated. The abdominal mass was aspirated and cytologically diagnosed as a neuroendocrine tumor, suspected to be a pheochromocytoma. Laboratory examination revealed a mild anemia and thrombocytopenia, markedly elevated ATP and ALP activities, and moderate hypercalcemia. A low‐dose dexamethasone suppression test and endogenous adrenocorticotropic hormone (ACTH) concentration were compatible with pituitary hyperadrenocorticism. On urinalysis, proteinuria was noted as well as a high urine metanephrine/creatinine ratio, consistent with a diagnosis of pheochromocytoma. The dog was treated with supportive care and euthanized 6 months later due to decreasing quality of life. On necropsy, an extra‐adrenal pheochromocytoma (paraganglioma) was diagnosed in the caudal abdomen, and a pituitary adenoma and an osteosarcoma of the right distal radius were confirmed.     

A case of chronic lymphocytic leukemia masked by Cushing’s disease in a dog

A 12-year-old, 3.5-kg, intact female dog was presented with polyuria, polydipsia, and a pendulous abdomen. Laboratory examinations showed elevated hepatobiliary enzyme levels and neutrophilic leukocytosis. The adrenocorticotropic hormone stimulation test confirmed hyperadrenocorticism (HAC). Trilostane therapy managed the clinical condition and cortisol concentration. However, lymphocytosis and nonregenerative anemia developed after HAC remission. Bone marrow aspiration analysis revealed a lymphoproliferative disorder with a clonal T-cell population. Accordingly, the patient was diagnosed with T-cell chronic lymphocytic leukemia (CLL) and concurrent HAC. Thereafter, chemotherapy was initiated, which improved the lymphocytosis. However, euthanasia was performed because of worsening quality of life at 45 weeks after the first presentation. These results suggested that CLL could be masked by excessive endogenous cortisol and discovered after HAC remission.     

Isolation of multidrug-resistant (MDR) Mycobacterium bovis from a dog in Korea

A 3-year-old female Miniature Schnauzer dog with a week-long history of generalized intention tremor and progressive weight loss for several months was admitted. Mild anemia, fever, splenomegaly, aseptic cerebral meningitis and systemic lymph nodes enlargement were examined through erythrogram, ultrasonography, computed tomography and magnetic resonance imaging. Mycobacterium bovis was identified via molecular microbiology having the same molecular type as that of isolates from a cattle farm previously identified. However, the dog was raised in a city. The M. bovis had multidrug resistance (MDR)-bearing mutations in both katG and rpoB genes toward first-line antibiotics. To the best of our knowledge, this is the first report describing an MDR M. bovis infection of a dog in Korea.     

Gastrointestinal pythiosis with concurrent presumptive gastrointestinal basidiobolomycosis in a Boxer dog

A 2‐year‐old female spayed Boxer dog was presented for a 1‐month history of progressive hemorrhagic diarrhea with tenesmus and weight loss despite trial courses of antibiotics and diet change. Abdominal ultrasound revealed severe, focal thickening, and loss of normal architecture of the colonic wall with abdominal lymphadenomegaly. Dry‐mount fecal cytology, performed on several consecutive days, consistently revealed numerous, round, 16‐20 μm structures with basophilic, granular content, and a thin cell wall. Transmission electron microscopy identified these structures as fungi. Culture, polymerase chain reaction (PCR), and sequencing of the internal transcribed spacer, D1/D2 regions, and DNA‐directed RNA polymerase II core subunit (RPB2) confirmed the presence of Basidiobolus microsporus in the feces. Biopsies collected via ileocolonoscopy revealed marked, multifocal, chronic, neutrophilic, and eosinophilic ileitis and colitis with ulceration, granulation tissue, and intralesional hyphae (identified with Gomori methenamine silver stain). A Pythium enzyme‐linked immunosorbent assay and Pythium‐specific PCR performed on the formalin‐fixed paraffin‐embedded biopsy specimens were positive while Basidiobolus‐specific PCR was negative, thus confirming a diagnosis of pythiosis. This report describes a fatal case of colonic and intestinal pythiosis with the presence of fecal Basidiobolus sp. spores, suggestive of concurrent gastrointestinal basidiobolomycosis.     

Nasal infection with Scedosporium apiospermum in a dog

CASE HISTORY: A 2-year-old female Siberian Husky was presented with a 6-month history of sneezing and mucous discharge from the right nostril.

CLINICAL FINDINGS: Reduced airflow through the right nostril was evident. Radiographs showed subtle loss of detail of turbinates within the right nasal chamber. Rhinoscopy revealed swollen and erythematous turbinates and a white mass within the caudal aspect of the right nasal cavity. Histopathologically, there was a heavy mixed inflammatory infiltrate in the submus- cosa of the right turbinate, and the presence of fungal hyphae and spores in the white mass. A heavy growth of Scedosporium apiospermum was cultured from the mass.

DIAGNOSIS: Chronic rhinitis of the right nasal cavity and infection with S. apiospermum.

CLINICAL RELEVANCE: This is the first reported case of S. apiospermum isolated from the nasal cavity of a dog in New Zealand. Fungal culture is necessary to differentiate this fungus from Aspergillus spp.     

Efficacy of transsphenoidal hypophysectomy in treatment of dogs with pituitary-dependent hyperadrenocorticism

The long-term survival, disease-free fractions, and the complications of hypophysectomy in 150 dogs with pituitary-dependent hyperadrenocorticism (PDH) were examined in a prospective study. Long-term survival and disease-free fractions in relation to pituitary size were analyzed by the Kaplan-Meijer estimate procedure. The 1-, 2-, 3-, and 4-year estimated survival rates were 84% (95% confidence interval [CI], 76-89%), 76% (67-83%), 72% (62-79%), and 68% (55-77%), respectively. Treatment failures included procedure-related mortalities (12 dogs) and incomplete hypophysectomies (9 dogs). The 1-, 2-, 3-, and 4-year estimated relapse-free fractions were 88% (CI: 80-93%), 75% (64-83%), 66% (54-76%), and 58% (45-70%), respectively. Postoperative reduction of tear production (58 eyes in 47 dogs) was often reversible but remained low until death in 11 eyes of 10 dogs. Central diabetes insipidus (CDI) occurred more frequently (62%) in dogs with enlarged pituitaries than in dogs with nonenlarged pituitaries (44%). Survival and disease-free fractions after hypophysectomy were markedly higher in dogs with nonenlarged pituitaries than in dogs with enlarged pituitaries. Transsphenoidal hypophysectomy is an effective treatment for PDH in dogs. The survival and disease-free fractions after hypophysectomy decrease and the incidence of CDI increases with increasing pituitary size. Therefore, early diagnosis of PDH is important and transsphenoidal hypophysectomy is expected to have the best outcome when used as primary treatment for dogs with nonenlarged or moderately enlarged pituitaries.     

Inguinal panniculitis in a young Tasmanian devil (Sarcophilus harrisii) caused by Mycobacterium mageritense

A 1-year-old, entire male Tasmanian devil living in captivity was presented because of a nodular inguinal lesion that subsequently developed a draining sinus tract. A second, similar lesion developed later in the ipsilateral axillary region. A deep representative biopsy specimen of abnormal subcutaneous tissue showed chronic active pyogranulomatous inflammation and beaded Gram-positive and acid-fast bacilli situated in lipid vacuoles within the lesion. A rapidly growing Mycobacterium species, shown subsequently to be M. mageritense, was grown from a swab of the primary lesion. It was susceptible to tetracyclines (including doxycycline) and moxifloxacin in vitro. The lesions resolved following treatment with doxycycline monohydrate (50 mg PO once daily) and then moxifloxacin (10 mg/kg PO for 20 days). The infection probably resulted from inoculation of subcutaneous tissues by material containing this Mycobacterium following fight or bite injuries. The presentation is reminiscent of similar lesions attributable to rapidly growing mycobacterial infections of the subcutis observed in domestic cats and quolls.     

Na(+), K(+)-ATPase content in skeletal muscle of dogs with pituitary-dependent hyperadrenocorticism

Several hormones regulate Na⁺, K⁺-ATPase content in the muscle cell membrane, which is essential for maintaining muscle cell excitability. Chronic glucocorticoid excess is associated with muscle weakness and reduced endurance. We hypothesized that chronic glucocorticoid excess affects Na⁺, K⁺-ATPase content in canine skeletal muscle, and contributes to reduced endurance and muscle weakness associated with pituitary-dependent hyperadrenocorticism (PDH) in dogs. Therefore, Na⁺, K⁺-ATPase content in skeletal muscle was evaluated before and after hypophysectomy and hormone replacement (cortisone and l-thyroxin) in dogs with PDH (n = 13), and in healthy controls (n = 6). In addition, baseline and exercise-induced changes in plasma electrolyte concentrations and acid–base balance were evaluated before and after hypophysectomy in dogs with PDH. Na⁺, K⁺-ATPase content of gluteal muscle in dogs with PDH was significantly lower than in control dogs (201 ± 13 pmol/g versus 260 ± 8 pmol/g wet weight; P < 0.01). Similar differences were found in palatine muscle. After hypophysectomy and on hormone replacement, Na⁺, K⁺-ATPase was increased (234 ± 7 pmol/g wet weight). Both plasma pH and base excess in dogs with PDH (7.44 ± 0.01; 1.7 ± 0.6 mmol/l, respectively) were significantly higher (P < 0.05) than after hypophysectomy and hormone replacement (7.41 ± 0.01; −0.2 ± 0.4 mmol/l, respectively). Exercise induced respiratory alkalosis, but did not result in hyperkalemia in dogs with PDH. In conclusion, chronic glucocorticoid excess in dogs with PDH is associated with decreased Na⁺, K⁺-ATPase content in skeletal muscle. This may contribute to reduce endurance in canine PDH, although dogs with PDH did not exhibit exercise-induced hyperkalemia. Na⁺, K⁺-ATPase content normalized to values statistically not different from healthy controls after hypophysectomy and hormone replacement.     

Quantitative CT assessment of bone mineral density in dogs with hyperadrenocorticism

Canine hyperadrenocorticism (HAC) is one of the most common causes of general osteopenia. In this study, quantitative computed tomography (QCT) was used to compare the bone mineral densities (BMD) between 39 normal dogs and 8 dogs with HAC (6 pituitary-dependent hyperadrenocorticism [PDH]; pituitary dependent hyperadrenocorticism, 2 adrenal hyperadrenocorticism [ADH]; adrenal dependent hyperadrenocorticism) diagnosed through hormonal assay. A computed tomogaraphy scan of the 12th thoracic to 7th lumbar vertebra was performed and the region of interest was drawn in each trabecular and cortical bone. Mean Hounsfield unit values were converted to equivalent BMD with bone-density phantom by linear regression analysis. The converted mean trabecular BMDs were significantly lower than those of normal dogs. ADH dogs showed significantly lower BMDs at cortical bone than normal dogs. Mean trabecular BMDs of dogs with PDH using QCT were significantly lower than those of normal dogs, and both mean trabecular and cortical BMDs in dogs with ADH were significantly lower than those of normal dogs. Taken together, these findings indicate that QCT is useful to assess BMD in dogs with HAC.