Leishmaniasis is a disease caused by microscopic parasites that can affect both people and animals. Dogs are the most affected domestic animals, but cats can also become infected. Until now, this parasite had never been confirmed in a domestic cat in Costa Rica using advanced molecular tests. In this case, a pet cat was taken to a veterinary clinic because the owner noticed a small, painless lump on one of its back legs. The cat seemed otherwise healthy. Blood tests ruled out viral diseases that weaken the immune system in cats. Ultrasound examination showed enlarged lymph nodes and spleen, which suggested possible internal involvement. A small sample taken from the lump showed cells containing structures compatible with the parasite. The mass was surgically removed and analyzed using molecular techniques that detect the parasite’s genetic material. These tests confirmed the presence of Leishmania (L.) infantum. Surprisingly, the removed tissue showed only inflammation and no visible parasites under the microscope. After surgery, the cat did not receive antiparasitic treatment. Seven months later, the cat remained completely healthy, and the lump did not return. This suggests that some cats may be able to control the infection naturally. This case is important because it shows that this parasite is still present in Costa Rica, even in areas where it had not been detected for many years. It also highlights the need for veterinarians to consider leishmaniasis as a possible cause of skin lumps in cats, even when the animal appears healthy.

Case series summary A 2-year-old neutered male domestic shorthair cat presented with severe lethargy, hyporexia, dehydration, and poor body condition. The incidence of polyuria/polydipsia was unknown because of the presence of multiple other cats in the household. Laboratory findings revealed severe hypernatremia, isosthenuria, hemoconcentration, and moderate azotemia. MRI of the head demonstrated partial hypoplasia/aplasia of the hypothalamus and pituitary gland, confirming congenital central diabetes insipidus; additional endocrine testing excluded other causes. Initial fluid therapy improved azotemia and stabilized the hematocrit, but hypernatremia persisted until desmopressin therapy was initiated. The cat was successfully managed long-term with gradually titrated oral desmopressin, achieving normalization of electrolytes. Relevance and novel information This report details the first documented case of central diabetes insipidus in an adult cat, attributed to presumed partial aplasia of the hypothalamus and pituitary gland, with no other hormonal deficiencies.

Case summary Two rescued juvenile cats with unilateral severe shoulder deformities suspected to be secondary to septic arthritis were referred for further management. Comprehensive diagnostic evaluations confirmed shoulder deformity with suspected septic arthritis in both cases. Due to the poor prognosis for preserving shoulder joint function, shoulder arthrodesis was performed to relieve pain and restore forelimb weight-bearing ability. At 6 and 8 years postoperatively, both cats exhibited normal motor function in the affected limbs, no signs of lameness, and maintained a good quality of life. No evidence of osteomyelitis or implant failure was noted. These findings suggest that arthrodesis may be a viable and effective long-term treatment option for irreparable shoulder joint disorders in cats. Relevance and novel information Shoulder joint injuries and disorders are less common in cats than in dogs, and only a limited number of reports exist in the small animal orthopedic literature. In clinical practice, shoulder deformity (SD) in small animals is rarely documented, with few references regarding its etiology and pathophysiology. This report presents two cases of SD in rescued cats, demonstrating that shoulder arthrodesis can be an effective treatment for irreparable feline shoulder joint disorders. To the best of our knowledge, this is the first report to describe long-term clinical and radiographic outcomes of shoulder arthrodesis in cats with SD.

Case summary A 5-year-old British Shorthair cat was diagnosed with pemphigus foliaceus (PF) and was initially treated with methylprednisolone (0.7 mg/kg q12h), which possibly resulted in congestive heart failure (CHF). Treatment was switched to dexamethasone (0.09 mg/kg q24h) and mycophenolate mofetil (MMF) (10 mg/kg q12h) was added as a steroid-sparing agent. Although dexamethasone was slowly tapered off, MMF alone successfully maintained PF in remission. After 15 weeks of treatment, blood tests showed neutropenia and thrombocytopaenia. MMF dose reduction (10 mg/kg q24h) resulted in the normalisation of haematological parameters, although a mild flare of PF occurred. The reintroduction of dexamethasone (0.09 mg/kg twice weekly) rapidly restored disease control. MMF (10 mg/kg q24h) and dexamethasone (0.045 mg/kg twice weekly) were continued as maintenance therapy. After 36 weeks, the cat remained in clinical remission without further complications. Relevance and novel information To the best of the authors’ knowledge, this is the first case report to describe the use of MMF in a cat with PF. MMF was well tolerated and it was able to manage clinical signs even after the discontinuation of corticosteroids. Since mild and reversible haematological abnormalities were observed, careful monitoring during MMF administration is recommended. In this case, MMF dose reductions led to flares requiring a temporary reintroduction of corticosteroids to maintain disease control. MMF could be useful as an alternative treatment in cats affected by comorbidities where corticosteroid monotherapy would pose risks.

Case summary Toxoplasma gondii is a globally distributed apicomplexan protozoan infecting all warm-blooded animals. Cats are the definitive host, susceptible to clinical disease. In Spain, studies have shown the widespread presence of Toxoplasma IgG antibodies in cats but there are no published data on clinical toxoplasmosis in cats from Spain. We describe a case of fatal disseminated toxoplasmosis in a 7-year-old outdoor domestic shorthair cat. The cat, an active hunter, was presented with a 1-week history of malaise and acute deterioration over 24 h. Fever, tachypnoea and abdominal discomfort were detected on physical examination. No evidence of immunosuppressive disease or previous treatment could be found. A moderate increase in alanine aminotransferase (ALT) and aspartate aminotransferase (AST) was found on serum biochemistry. Radiography revealed hepatomegaly and a small patchy pulmonary alveolar pattern in the caudal lung lobes. In 48 h, the AST and ALT levels were severely increased and the cat’s respiratory signs worsened. Parenteral clindamycin administration (25 mg/kg IV q12h) and supportive treatment could not prevent progression to death. Cytology from the liver and lungs revealed organisms morphologically consistent with T gondii. Indirect immunofluorescence antibody test Toxoplasma titres were 1:100 IgM and 1:100 IgG. PCR performed on scraped material from glass cytology slides was positive for T gondii in both lung and liver aspirates. Relevant and novel information To the authors’ knowledge, this is the first case of fatal disseminated toxoplasmosis in a cat described in Spain, confirmed by PCR. Fine-needle aspirates from the liver could assist in the diagnosis of fatal disseminated toxoplasmosis when liver enzymes are increased.

Case summary This case report describes the clinical and pathological features of telangiectatic osteosarcoma (TOS) with brain invasion in a 4-year-old female domestic shorthair cat. The cat presented with respiratory distress, epistaxis, anorexia and significant nasal obstruction. A rhinoscopy revealed an amorphous white neoformation in the left nasal cavity. Despite treatment, the cat’s condition deteriorated and it succumbed to the disease. Necropsy and histopathologic examination revealed an infiltrative malignant neoplasm with osteoid matrix and sarcomatous cells surrounding blood-filled non-vascular spaces. Immunohistochemistry showed positive staining for bone cell markers and vimentin, while endothelial markers were negative, confirming TOS. Relevance and novel information Nasal diseases in cats present significant diagnostic challenges due to similar clinical signs, such as respiratory distress and nasal discharge. Nasal osteosarcomas are rare, and TOS is the rarest subtype, characterized by blood-filled spaces within an aggressive osteolytic lesion. This case highlights the diagnostic complexities and poor prognosis associated with TOS in cats, emphasizing the need for advanced imaging and immunohistochemical tests for accurate diagnosis. Given the aggressive nature and rapid progression of TOS, it should be considered in differential diagnoses of feline nasal obstructive lesions.

Case summary A 13-year-old castrated male American Shorthair cat was referred for evaluation following a 3-week history of poor balance and decreased activity. The MRI findings revealed a well-defined left caudal cerebellar mass with a diameter of 1.2 cm, consistent with a meningioma. CT and MRI scans did not reveal metastasis. After a suboccipital craniotomy, the mass was resected subtotally as a result of parenchymal invasion. A histopathological examination revealed a benign fibrous meningioma with invasion into the cerebellum at the tumour margins. Postoperatively, the cat remained asymptomatic for 25 months, but ataxia recurred, and tumour recurrence was confirmed using MRI and post-mortem examination. Relevance and novel information This case demonstrates that even feline meningiomas with benign features can exhibit brain invasion. Since brain invasion is an indicator of malignancy in meningioma, a detailed histopathological evaluation of the tumour margins is essential for accurate grading and prognosis.

Case summary A 7-year-old domestic shorthair cat was presented for periuria, apathy, fever, inappetence, diarrhoea and vomiting. A complete blood count and biochemistry analysis revealed severe thrombocytopenia, severe azotaemia, moderate panhypoproteinemia, mildly elevated DGGR lipase activity and mildly elevated liver enzyme activity. Abdominal ultrasound showed a hypoechoic pancreas with surrounding hyperechoic fat demonstrating dirty shadowing and ascites (protein-poor transudate). The cat was treated medically for pancreatitis with fluid therapy, antiemetics and pain medication. During the hospitalisation period, the cat developed severe anaemia and received multiple whole blood transfusions yet showed no signs of clinical improvement. A repeat ultrasound examination performed after 8 days showed progressive pancreatic lesions and ongoing ascites. Analysis of the free abdominal fluid revealed neutrophilic inflammation despite low protein and cell concentration, with the presence of numerous very small, coccoid, basophilic inclusions within neutrophils, raising the concern for a septic peritonitis due to Mycoplasma species. Quantitative PCR (qPCR) confirmed the presence of Mycoplasma felis. After 10 days of hospitalisation, the cat developed refractory septic shock and was euthanased. Necropsy revealed severe necrotising pancreatitis with systemic changes consistent with sepsis and microthrombi. qPCR testing for M felis in pancreatic tissue also yielded a positive result. Relevance and novel information Although pancreatitis is a common disease in cats, this case report presents the first documented occurrence of M felis as the suspected primary pathogen causing pancreatitis in a cat.