Renal alterations in cats (Felis catus) housed in shelters and affected by systemic AA-amyloidosis: Clinicopathological data, histopathology, and ultrastructural features.

AA-amyloidosis is frequent in shelter cats, and chronic kidney disease is the foremost cause of death. The aims were to describe kidney laboratory and microscopic findings in shelter cats with AA-amyloidosis. Cats were included if kidney specimens were collected post-mortem and laboratory data were available within 6 months before death. Renal lesions were evaluated with optical and electron microscopy. Mass spectrometry was used to characterize amyloid. Nine domestic short-hair cats were included; 4 females and 5 males with a median age of 8 years (range = 2-13). All cats had blood analyses and urinalyses available. Serum creatinine concentrations were increased in 6 cats and symmetric dimethylarginine was increased in all of the cats. All of the cats had proteinuria. Eight of 9 cats had amyloid in the medulla, and 9 had amyloid in the cortex (glomeruli). All cats had amyloid in the interstitium. Six cats had concurrent interstitial nephritis and 1 had membranoproliferative glomerulonephritis. All cats had extrarenal amyloid deposits. Amyloid was AA in each case. In conclusion, renal deposition of amyloid occurs in both cortex and medulla in shelter cats and is associated with azotemia and proteinuria. Renal involvement of systemic AA-amyloidosis should be considered in shelter cats with chronic kidney disease. The cat represents a natural model of renal AA-amyloidosis.

Hypokalaemic myopathy associated with iatrogenic hypercorticism in a cat.

Case summary: A 12-year-old castrated male domestic shorthair cat was referred for investigation of lethargy, hindlimb weakness with plantigrade stance and ventroflexion of the neck. The cat was fed a balanced diet and had received methylprednisolone acetate at a dose of 20 mg intramuscularly every 6 months for 6 years. On blood work, severe hypokalaemia and marked elevation of muscle enzymes were noticeable. The findings were suggestive of hypokalaemic myopathy. Urine fractional excretion of potassium (FEk) was moderately high (9.04%), and serum aldosterone was below the reference interval. An adrenocorticotropic hormone (ACTH) stimulation test was compatible with adrenal suppression. Upon hospitalisation, the patient was given intravenous (IV) Ringer lactate solution supplemented with potassium chloride and oral potassium citrate. The serum potassium concentration normalised by the fifth day of hospitalisation; therefore, IV potassium supplementation was suspended. The cat was discharged with oral potassium and the dose was gradually reduced over time. After 4 months, the cat was clinically normal; the serum potassium concentration remained within the normal range and the adrenal glands showed some response to ACTH stimulation. Potassium supplementation was therefore discontinued. One month later, the serum potassium concentration was still within normal limits and at the time of writing (7 months after presentation), no clinical signs had reoccurred. Relevance and novel information: This report describes a case of hypokalaemic myopathy associated with iatrogenic hypercorticism in a cat. This condition was successfully treated with supplementation of potassium and a complete clinical remission was achieved within 4 months.

Renal amyloid-A amyloidosis in cats: Characterization of proteinuria and biomarker discovery, and associations with kidney histology.

BACKGROUND: Amyloid A (AA) amyloidosis is a protein misfolding disease arising from serum amyloid A (SAA). Systemic AA amyloidosis recently was shown to have a high prevalence in shelter cats in Italy and was associated with azotemia and proteinuria. OBJECTIVES: Investigate urine protein profiles and diagnostic biomarkers in cats with renal AA amyloidosis. ANIMALS: Twenty-nine shelter cats. METHODS: Case-control study. Cats with renal proteinuria that died or were euthanized between 2018 and 2021 with available necropsy kidney, liver and spleen samples, and with surplus urine collected within 30 days before death, were included. Histology was used to characterize renal damage and amyloid amount and distribution; immunohistochemistry was used to confirm AA amyloidosis. Urine protein-to-creatinine (UPC) and urine amyloid A-to-creatinine (UAAC) ratios were calculated, and sodium dodecyl sulfate-agarose gel electrophoresis (SDS-AGE) and liquid chromatography-mass spectrometry (LC-MS) of proteins were performed. RESULTS: Twenty-nine cats were included. Nineteen had AA amyloidosis with renal involvement. Cats with AA amyloidosis had a higher UPC (median, 3.9; range, 0.6-12.7 vs 1.5; 0.6-3.1; P = .03) and UAAC ratios (median, 7.18 × 10-3 ; range, 23 × 10-3 -21.29 × 10-3 vs 1.26 × 10-3 ; 0.21 × 10-3 -6.33 × 10-3 ; P = .04) than unaffected cats. The SDS-AGE identified mixed-type proteinuria in 89.4% of cats with AA amyloidosis and in 55.6% without AA amyloidosis (P = .57). The LC-MS identified 63 potential biomarkers associated with AA amyloidosis (P < .05). Among these, urine apolipoprotein C-III was higher in cats with AA amyloidosis (median, 1.38 × 107 ; range, 1.85 × 105 -5.29 × 107 vs 1.76 × 106 ; 0.0 × 100 -1.38 × 107 ; P = .01). In the kidney, AA-amyloidosis was associated with glomerulosclerosis (P = .02) and interstitial fibrosis (P = .05). CONCLUSIONS AND CLINICAL IMPORTANCE: Renal AA amyloidosis is associated with kidney lesions, increased proteinuria and increased urine excretion of SAA in shelter cats. Additional studies are needed to characterize the role of lipid transport proteins in the urine of affected cats.

Histological evaluation of the distribution of systemic AA-amyloidosis in nine domestic shorthair cats.

Amyloidosis is a group of protein-misfolding disorders characterized by the accumulation of amyloid in organs, both in humans and animals. AA-amyloidosis is considered a reactive type of amyloidosis and in humans is characterized by the deposition of AA-amyloid fibrils in one or more organs. In domestic shorthair cats, AA-amyloidosis was recently reported to be frequent in shelters. To better characterize this pathology, we report the distribution of amyloid deposits and associated histological lesions in the organs of shelter cats with systemic AA-amyloidosis. AA-amyloid deposits were identified with Congo Red staining and immunofluorescence. AA-amyloid deposits were then described and scored, and associated histological lesions were reported. Based on Congo Red staining and immunofluorescence nine shelter cats presented systemic AA-amyloidosis. The kidney (9/9), the spleen (8/8), the adrenal glands (8/8), the small intestine (7/7) and the liver (8/9) were the organs most involved by amyloid deposits, with multifocal to diffuse and from moderate to severe deposits, both in the organ parenchyma and/or in the vascular compartment. The lung (2/9) and the skin (1/8) were the least frequently involved organs and deposits were mainly focal to multifocal, mild, vascular and perivascular. Interestingly, among the organs with fibril deposition, the stomach (7/9), the gallbladder (6/6), the urinary bladder (3/9), and the heart (6/7) were reported for the first time in cats. All eye, brain and skeletal muscle samples had no amyloid deposits. An inflammatory condition was identified in 8/9 cats, with chronic enteritis and chronic nephritis being the most common. Except for secondary cell compression, other lesions were not associated to amyloid deposits. To conclude, this study gives new insights into the distribution of AA-amyloid deposits in cats. A concurrent chronic inflammation was present in almost all cases, possibly suggesting a relationship with AA-amyloidosis.

AA-amyloidosis in cats (Felis catus) housed in shelters.

Systemic AA-amyloidosis is a protein-misfolding disease characterized by fibril deposition of serum amyloid-A protein (SAA) in several organs in humans and many animal species. Fibril deposits originate from abnormally high serum levels of SAA during chronic inflammation. A high prevalence of AA-amyloidosis has been reported in captive cheetahs and a horizontal transmission has been proposed. In domestic cats, AA-amyloidosis has been mainly described in predisposed breeds but only rarely reported in domestic short-hair cats. Aims of the study were to determine AA-amyloidosis prevalence in dead shelter cats. Liver, kidney, spleen and bile were collected at death in cats from 3 shelters. AA-amyloidosis was scored. Shedding of amyloid fibrils was investigated with western blot in bile and scored. Descriptive statistics were calculated. In the three shelters investigated, prevalence of AA-amyloidosis was 57.1% (16/28 cats), 73.0% (19/26) and 52.0% (13/25), respectively. In 72.9% of cats (35 in total) three organs were affected concurrently. Histopathology and immunofluorescence of post-mortem extracted deposits identified SAA as the major protein source. The duration of stay in the shelters was positively associated with a histological score of AA-amyloidosis (B = 0.026, CI95% = 0.007-0.046; p = 0.010). AA-amyloidosis was very frequent in shelter cats. Presence of SAA fragments in bile secretions raises the possibility of fecal-oral transmission of the disease. In conclusion, AA-amyloidosis was very frequent in shelter cats and those staying longer had more deposits. The cat may represent a natural model of AA-amyloidosis.

Case report: Atypical and chronic masticatory muscle myositis in a 5-month old Cavalier King Charles Spaniel. Clinical and diagnostic findings, treatment and successful outcome.

Masticatory muscle myositis (MMM) is the second most common inflammatory myopathy diagnosed in dogs, but it is rarely described in puppies. The disease is characterized by the production of autoantibodies against 2M myofibers contained in masticatory muscle, although the cause of this production is still unclear. The aim of the present case report was to describe the clinical presentation, diagnostic findings, treatment, and follow-up of an atypical case of chronic masticatory muscle myositis in a very young dog. A 5-month old Cavalier king Charles Spaniel (CKCS) was presented to the AniCura Istituto Veterinario Novara with a two weeks, progressive history of lethargy and difficulty in food prehension. Neurological examination revealed bilateral masticatory muscle atrophy, mandibular ptosis with the jaw kept open, inability to close the mouth without manual assistance, jaw pain, and bilateral reduction of palpebral reflex and menace reaction; vision was maintained. A myopathy was suspected. Computed tomography (CT), magnetic resonance imaging (MRI), enzyme-linked immunosorbent assay test for 2M antibodies, and histopathological examination of masticatory muscle biopsy confirmed the diagnosis of MMM. Glucocorticoids treatment was started and clinical signs promptly improved. To the authors' knowledge, this is the first case describing mandibular ptosis in a dog affected by chronic MMM, successfully managed with medical treatment and the first report describing the CT and MRI findings in a young CKCS affected by MMM.

A longitudinal observational study in two cats naturally-infected with hepadnavirus.

Hepatitis B virus (HBV) is a major cause of liver disease in humans including chronic hepatitis and hepatocellular carcinoma. Domestic cat hepadnavirus (DCH), a novel HBV-like hepadnavirus, was identified in domestic cats in 2018. From 6.5 %-10.8 % of pet cats are viremic for DCH and altered serological markers suggestive of liver damage have been identified in 50 % of DCH-infected cats. DCH DNA has been detected in association with characteristic lesions of chronic hepatitis and with hepatocellular carcinoma in cats, suggesting a possible association. In this study longitudinal molecular screening of cats infected with DCH was performed to determine if DCH can cause chronic infections in cats. Upon re-testing of sera from five DCH-positive animals, 2-10 months after the initial diagnosis, three cats tested negative for DCH on two consecutive occasions using quantitative PCR. Two other cats remained DCH-positive, including an 8-month-old female cat re-tested four months after the initial positive result, and a 9-year-old male cat, which tested positive for DCH on six occasions over an 11-month period. The latter had a history of chronic hepatopathy with jaundice, lethargy and elevated serum alanine transaminase levels (ALT). During the period of observation, DCH titers ranged between 1.64 × 105 and 2.09 × 106 DNA copies/mL and ALT was persistently elevated, suggesting chronic infection. DCH DNA was not detected in oral, conjunctival, preputial and rectal swabs from the two animals collected at several time points. Long-term (chronic) infection would be consistent with the relatively high number of viremic cats identified in epidemiological investigations, with the possible association of DCH with chronic hepatic pathologies and with what described with HBV in human patients.

Treatment with Class A CpG Oligodeoxynucleotides in Cats with Naturally Occurring Feline Parvovirus Infection: A Prospective Study.

Feline parvovirus (FPV) causes severe gastroenteritis and leukopenia in cats; the outcome is poor. Information regarding specific treatments is lacking. Class A CpG oligodeoxynucleotides (CpG-A) are short single-stranded DNAs, stimulating type I interferon production. In cats, CpG-A induced an antiviral response in vivo and inhibited FPV replication in vitro. The aim was to prospectively investigate the effects of CpG-A on survival, clinical score, hematological findings, antiviral response (cytokines), viremia, and fecal shedding (real-time qPCR) in cats naturally infected with FPV. Forty-two FPV-infected cats were randomized to receive 100 µg/kg of CpG-A (n = 22) or placebo (n = 20) subcutaneously, on admission and after 48 h. Blood and fecal samples were collected on admission, after 1, 3, and 7 days. All 22 cats showed short duration pain during CpG-A injections. The survival rate, clinical score, leukocyte and erythrocyte counts, viremia, and fecal shedding at any time-point did not differ between cats treated with CpG-A (50%) and placebo (40%). Antiviral myxovirus resistance (Mx) gene transcription increased in both groups from day 1 to 3 (p = 0.005). Antibodies against FPV on admission were associated with survival in cats (p = 0.002). In conclusion, CpG-A treatment did not improve the outcome in cats with FPV infection. FPV infection produced an antiviral response.

Carcinosarcoma of the biliary system in a cat.

A 12-year-old, mixed-breed domestic cat was diagnosed with a multicystic hepatic mass via ultrasonographic examination and computer tomography scan. The tumor associated with the left medial liver lobe, and connected by a thin stalk to the hilar region, was surgically removed. The mass was firm, encapsulated, mottled white to red black, multinodular, and cystic. Histologic diagnosis was carcinosarcoma supported by positive immunohistochemistry for cytokeratins and vimentin of atypical neoplastic cell populations. On the basis of morphology, the origin was considered to be in the biliary tract. Biliary carcinosarcoma is a rare neoplasm that occurs in people. The epidemiology and risk factors have not yet been determined, and the prognosis is poor except for cases in which curative resection is performed.

Survival time and prognostic factors in cats with newly diagnosed diabetes mellitus: 114 cases (2000-2009).

OBJECTIVE: To determine overall survival time and identify prognostic factors associated with survival time in cats with newly diagnosed diabetes mellitus. DESIGN: Retrospective case series. ANIMALS: 114 cats with newly diagnosed diabetes mellitus. PROCEDURES: Data for analysis included history, signalment, physical examination findings, hematologic and serum biochemical data, presence of ketoacidosis, and diagnosis of concurrent diseases at initial evaluation. The effects of possible predictors on survival time were determined by calculating hazard ratios (HRs) and 95% confidence intervals (CIs). RESULTS: Median survival time of diabetic cats was 516 days (range, 1 to 3,468 days); 70%, 64%, and 46% lived longer than 3, 6, and 24 months, respectively. Survival time was significantly shorter for cats with higher creatinine concentrations, with a hazard of dying approximately 5% greater for each increase of 10 µg/dL in serum creatinine concentration (adjusted HR, 1.005; 95% CI, 1.003 to 1.007). Ketoacidosis was not significantly associated with survival time (HR, 1.02; 95% CI, 0.590 to 1.78). CONCLUSIONS AND CLINICAL RELEVANCE: Cats with newly diagnosed diabetes mellitus had a fair to good prognosis. High serum creatinine concentration at diagnosis was associated with a poor outcome, likely because of the adverse effects of renal dysfunction. Ketoacidosis apparently was not associated with decreased survival time, suggesting that this complication should not necessarily be regarded as unfavorable.