Table of Contents and Abstracts

Objective
To estimate the prevalence of carbapenem-resistant Enterobacterales (CRE) fecal carriage in equine, canine, and feline patients at the Atlantic Veterinary College (Charlottetown, Prince Edward Island), a Canadian teaching and referral hospital.

Animals and procedure
Fifty-seven fresh, naturally voided fecal samples from 32 canine, 21 equine, and 4 feline Atlantic Veterinary College patients were collected and processed in June and July 2025. Samples were processed using selective culture, followed by MALDI-TOF MS and phenotypic assays for screening and detection of CRE and Enterobacterales species with reduced susceptibility to carbapenems. Relevant patient data were obtained to assess for associations with CRE and carbapenem susceptibility status.

Results
One canine Morganella morganii isolate was classified as CRE (sample-level prevalence: 1.8%), but carbapenemases were not detected. Twelve (21%) samples grew Enterobacterales on MacConkey plates supplemented with meropenem, indicating reduced susceptibility to carbapenems.

Conclusion and clinical relevance
The low prevalence of CRE within this Canadian sample is reassuring; however, the presence of CRE and high proportion with reduced susceptibility to meropenem underscore the importance of readying measures for early detection and control of CRE in veterinary patients and ensuring strong compliance with clinic infection-control practices. Carbapenem-resistant Enterobacterales outbreaks at Canadian veterinary hospitals, as documented elsewhere, remain a concern.

A 15-month-old intact female rat was presented with worsening lethargy and dysorexia present for 1 wk and bruxism present for 3 d. The diet was fruits, vegetables, and granola. On presentation, the rat was mildly dehydrated and had marked incisor malocclusion with enamel hypoplasia. On oral examination, the left mandibular molars were not visible and the gum line was prominent. Black punctate enamel discoloration was observed multifocally on molars, but no mucosal lesions were observed. The incisors were trimmed and the rat was discharged with analgesics, supportive care, and dietary recommendations. The rat’s condition continued to deteriorate and, 1 wk later, a left mandibular mass appeared that the owner perceived as painful. Computed tomography of the head showed lysis of the body of the left mandible, absence of left mandibular molar teeth, and abnormal soft-tissue attenuation in the left tympanic bulla. On the last visit (Day 31), purulent discharge was visible in the left external ear canal and along the left mandibular gingiva. Fine-needle aspiration and cytology of the mandibular mass suggested a keratinizing epithelial tumor of benign appearance. Euthanasia was elected, based on the poor prognosis. Histopathological examination revealed a well-differentiated oral squamous cell carcinoma of the left mandibular region with ipsilateral subacute purulent otitis media.

Key clinical message:
Squamous cell carcinoma should be included in the differential diagnosis of an infected, non-ulcerated oral mass in a rat.

Canine steroid-responsive meningitis-arteritis (SRMA) is an immune-mediated inflammatory disorder targeting the leptomeninges and associated vasculature with systemic inflammation and occasionally with mild systolic dysfunction and cardiac arrhythmias. Hypercoagulability has not been previously documented in dogs with SRMA, despite increases in inflammatory markers. This case report describes a 6-month-old female Australian heeler dog with acute progressive pyrexia and cervical hyperesthesia. Notable findings included marked decreased cardiac contractility and hypercoagulability determined via viscoelastic coagulation monitor and rotational thromboelastographic analysis. The SRMA was diagnosed based on clinical findings, cerebrospinal fluid analysis, magnetic resonance imaging, elimination of infectious causes of meningitis, and resolution of abnormalities after treatment with immunosuppressive medications. This is the first report describing severe systolic dysfunction and hypercoagulability in a dog with SRMA. The findings support routinely evaluating cardiac function and coagulation in dogs with SRMA and considering treatment with antithrombotic drugs when warranted.

Key clinical message:
It is important to consider cardiovascular and coagulation complications in dogs with SRMA. Dogs exhibiting atypical findings, such as arrythmia or unexplained clinical deterioration, may require further diagnostic workup. Early identification of these complications could necessitate the use of antithrombotic drugs and prompt monitoring of cardiac function to optimize patient outcomes.

Hemochromatosis is an uncommon condition in dogs. This report describes hemochromatosis of unknown origin in a dog breed not previously identified as predisposed to the condition. A 3-year-old spayed female German shepherd crossbred dog was presented to a local Saskatchewan veterinary clinic with weight loss, muscle wasting, chronic vomiting, diarrhea, and ascites of ~5 to 6 mo duration. The dog was treated symptomatically and was prescribed medication for potential liver failure. Due to poor response to treatment, the owners elected humane euthanasia. The dog was submitted for necropsy at Prairie Diagnostic Services (Western College of Veterinary Medicine, Saskatoon, Saskatchewan). Necropsy revealed hepatic cirrhosis indicated by severe portal bridging fibrosis and nodular regeneration with iron accumulation (hemosiderin) within the hepatocytes and Kupffer cells. Hemosiderin granules were also identified within the lymph nodes, pancreas, and kidneys. Toxicology testing revealed a highly elevated hepatic iron concentration that was subsequently interpreted as toxic (6479 ppm, wet weight basis). A diagnosis of hemochromatosis was made based on clinical history, gross necropsy findings, elevated hepatic iron concentration, and parenchymal hemosiderin deposition pattern in the liver. Given the lack of chronic exposure to iron, primary hemochromatosis was suspected. An underlying genetic cause was a possible etiology.

Key clinical message:
This case demonstrates the potential of hemochromatosis as a differential diagnosis for chronic liver disease. Due to currently limited noninvasive antemortem testing options and the potential for development of hepatic cirrhosis, early diagnosis and treatment of hemochromatosis is challenging.

Canine lymphoma is the most common hematopoietic malignancy, but the primary mediastinal form is rare. Progression from this form to systemic multicentric lymphoma has not been clearly documented in veterinary medicine, and optimal treatment strategies remain uncertain. This report describes a case of primary mediastinal T-cell lymphoma in a young dog that progressed to multicentric disease and was managed with chemotherapy and radiation therapy. A 2-year-old castrated male Shetland sheepdog was referred for evaluation of a cranial mediastinal mass detected on thoracic radiographs. On physical examination, bradycardia was noted, with all peripheral lymph nodes within normal limits. Laboratory abnormalities included severe hypercalcemia, elevated symmetric dimethylarginine, and the presence of large lymphocytes on blood smear. Cytology, polymerase chain reaction for antigen receptor rearrangements, and flow cytometry confirmed CD4⁺ T-cell mediastinal lymphoma. Initial treatment with the 25-week L-CHOP protocol achieved complete remission, but relapse occurred at Week 8, prompting radiation therapy to the mediastinal and submandibular masses. These lesions regressed but generalized peripheral lymphadenomegaly and a splenic honeycomb pattern developed, indicating progression to multicentric lymphoma. Based on ex vivo drug sensitivity testing, lomustine was initiated as rescue chemotherapy, achieving a second complete remission. Nevertheless, relapse occurred 38 d after the initial lomustine administration, and the dog ultimately died.

Key clinical message:
This case highlights the fact that progression from primary mediastinal to multicentric lymphoma may be associated with a poor prognosis in dogs. Radiation therapy demonstrated potential efficacy and warrants further investigation as a treatment option for canine mediastinal lymphoma.

The objective of this report was to document clinical remission of suspected familial proteinuria in a Bracco Italiano dog. A 4-year-old intact female Bracco Italiano with a familial history of amyloidosis was presented because of unilateral chemosis, polyuria, and polydipsia. Hypoalbuminemia and severe proteinuria were detected via initial diagnostics. Although no renal histopathologic assessment was done, there was a strong clinical suspicion for renal amyloidosis. The dog was treated with telmisartan and colchicine (in addition to other therapies) for proteinuria and achieved clinical remission > 5 y post-diagnosis.

Key clinical message:
Telmisartan is an appropriate 1st-line therapy for proteinuric dogs. Favorable long-term outcomes are possible for dogs with severe proteinuria. Prospective studies are warranted to evaluate effects of telmisartan on AA amyloidogenesis.

A 15-year-old spayed female domestic shorthair cat was referred because of a chronic history of swelling over the right eye that had progressed to an open, exudative wound. The lesion had not responded to prolonged antimicrobial treatments that were chosen based on superficial culture results. Before this development, the cat had been diagnosed with International Renal Interest Society (IRIS) stage 2 chronic kidney disease with no other significant health issues. Computed tomography revealed fluid to soft-tissue attenuating material in the sinonasal cavities and concurrent bony lysis. Cytology and biopsy of the frontal sinus cavity were suggestive of nocardiosis, which culture confirmed as Nocardia farcinica. Treatment using sulfonamide antibiotics was instituted and resulted in resolution of the clinical signs but did not provide a cure. The cat spontaneously died 1 y following the start of therapy due to causes unrelated to the N. farcinica infection, as confirmed by necropsy.

Key clinical message:
Nocardia spp. sinonasal infections are rare in small-animal patients but should be considered in cases of rhinosinusitis not responsive to empirical therapy. This report details management of a case of sinonasal nocardiosis in a cat with comorbidities.

A 13-year-old feline leukemia virus-negative cat was diagnosed with acute lymphoid B-cell aleukemic leukemia. The diagnosis was based on the combination of pancytopenia, large and atypical round cells present on liver and splenic cytology, bone marrow cytology and histopathology showing a majority nucleated population of atypical blast cells, immunohistochemistry, and a lack of malignant lymphoblasts observed in the peripheral blood. The cat was initially treated with L-asparaginase, vincristine, doxorubicin, cyclophosphamide, and prednisolone, which led to a resolution of the cytopenias. After relapse on Day 242, lomustine was first administered, followed by a modified protocol of vincristine, mitoxantrone, cyclophosphamide, and prednisolone, due to progressive disease. A survival time exceeding 1 y following diagnosis was obtained. This case highlights both a rare, aleukemic form of acute lymphoid leukemia in a feline leukemia virus-negative cat and an atypically prolonged survival time.

Key clinical message:
Prolonged survival of cats with acute lymphoid aleukemic leukemia is possible with chemotherapy treatment.

Objective
The objective of this study was to retrospectively assess medical records of goats presented to the J.T. Vaughan Large Animal Teaching Hospital at Auburn University (Alabama, USA) for evaluation and treatment of toxic or gangrenous mastitis, and to identify prognostic indicators for survival to hospital discharge.

Animals and procedure
Medical records of 35 postpartum female goats treated for toxic or gangrenous mastitis from December 2012 to January 2025 were analyzed. The diagnosis was based on mastitic changes to the mammary gland and milk, accompanied by systemic compromise. Following comparisons between discharged and non-discharged goats, continuous and categorical variables were included in univariate and multivariate regression models to evaluate their associations with the outcome.

Results
Of the study animals, 74% (26/35) survived to hospital discharge and the remaining 26% (9/35) died or were euthanized. Odds of hospital discharge increased [odds ratio (OR): 2.98; 95% confidence interval (CI): 1.44 to 7.97] for each 1°C increase in rectal temperature at admission (P = 0.002). However, odds of hospital discharge increased (OR: 11.21; 95% CI: 1.31 to 231.54) for each 1 g/dL increase in serum globulin concentration at admission (P = 0.02). For each additional day of hospitalization, goats treated for toxic mastitis were 2.35× more likely to be discharged from the hospital (OR: 2.35; 95% CI: 1.43 to 2.89; P < 0.01). Intramammary antibiotic (IMA) therapy increased the likelihood of hospital discharge 5.86× (95% CI: 1.28 to 31.5) compared to no IMA therapy (P = 0.02).

Conclusion and clinical relevance
Goats treated for toxic mastitis at the J.T. Vaughan Large Animal Teaching Hospital had a favorable prognosis for survival and discharge from the hospital. Hospitalization to ensure sufficient supportive care, as well as treatment with IMA, may improve survival in select cases.

Objective
Hyperkalemia is a frequent, life-threatening emergency in dogs and cats. It disrupts neuromuscular function and cardiac conduction. Clinicians need a clear physiologic framework to recognize risk and act quickly.

Animals and procedure
Part 1 of this 2-part review explains potassium homeostasis and the main causes of hyperkalemia in small animals. The article draws on peer-reviewed veterinary studies and core physiology, with direct patient-side relevance.

Results
Most body potassium is intracellular; small extracellular shifts alter membrane excitability and electrocardiogram patterns. Two systems control plasma potassium: transcellular control through insulin, β₂-adrenergic tone, and acid-base effects; and renal control through filtration, distal sodium delivery, tubular flow, and mineralocorticoid effect. Common clinical causes include decreased renal excretion (feline urethral obstruction, oligoanuric acute kidney injury, canine hypoadrenocorticism); transcellular shifts from intracellular to extracellular spaces (diabetic ketoacidosis, mineral metabolic acidosis, extensive tissue injury); increased intake or iatrogenic load when excretion is limited (potassium chloride in IV fluids, older stored blood, drugs that reduce aldosterone effect or distal sodium delivery); and pseudohyperkalemia due to sample factors (hemolysis, marked thrombocytosis or leukocytosis, anticoagulant contamination).

Conclusion and clinical relevance
Evaluate hyperkalemia in the full clinical context. In dogs, common causes include hypoadrenocorticism, acute kidney injury, and urinary tract obstruction or rupture. In cats, urethral obstruction and advanced renal failure predominate, whereas iatrogenic potassium load and severe metabolic acidosis are additional concerns. A firm grasp of both pathophysiology and etiology improves differential diagnosis and early decisions. Part 2 of this review will build on this foundation and outline diagnosis and treatment.