Use of computed tomography imaging during long-term follow-up of nine feline tuberculosis cases.

Case series summary Feline tuberculosis is an increasingly recognised potential zoonosis of cats. Treatment is challenging and prognosis can vary greatly between cases. Pulmonary infection requires extended courses of antibiotics, but methodologies for sensitively monitoring response to treatment are currently lacking. In this case series, we retrospectively examined the serial computed tomography (CT) findings in nine cats that had been diagnosed with tuberculosis. Changes in pathology (where applicable to tuberculosis) were correlated with the clinical presentation of each of the cats, the treatment protocol, and previous and contemporary diagnostic investigations. This study found that changes in CT findings during the medium- to long-term management of feline tuberculosis were highly variable between cats. The majority of cats had reduced pathology at re-examination during anti-tuberculous therapy, but pathology only resolved in a minority of cases. In some cases recurrence of pathology detected by CT imaging preceded clinical deterioration, allowing for rapid therapeutic intervention. Relevance and novel information When considered in combination with clinical findings, CT studies can aid in decision making regarding tapering of antibiotic protocols, or reintroduction of therapy in cases of recurrence or reinfection. This series also highlights that, in some cases, persistent abnormalities can be detected by CT, so complete resolution of CT pathology should not always be a goal in the management of feline tuberculosis.

Tuberculosis joint infections in four domestic cats.

CASE SERIES SUMMARY: This paper describes the clinical presentation, diagnostic imaging findings and outcome in four cats with confirmed joint-associated tuberculosis. The cats were 2-6 years of age, and immune competent. Three cases had tuberculosis affecting only one joint, whereas one case had at least three joints affected. Two cases were caused by Mycobacterium bovis, and the other two were caused by Mycobacterium microti. Radiological findings included osteolysis, periosteal reaction and associated soft tissue swelling. Two cases were euthanased and two cases responded well to amputation and follow-on antibiotic therapy. RELEVANCE AND NOVEL INFORMATION: To our knowledge, this is the first publication of a series of cats with joint-associated tuberculosis. Although tuberculosis is not common, a high degree of suspicion is needed to avoid delayed diagnosis. This case series highlights the importance of considering mycobacterial disease as a differential for joint disease in cats.

Computed tomographic findings in cats with mycobacterial infection.

OBJECTIVES: The objective of this study was to describe the CT imaging findings associated with confirmed mycobacterial infection in cats. METHODS: CT images from 20 cats with confirmed mycobacterial disease were retrospectively reviewed. Five cats underwent conscious full-body CT in a VetMouseTrap device. All other cats had thoracic CT performed under general anaesthesia, with the addition of CT investigation of the head/neck, abdomen and limbs in some cases. RESULTS: Mycobacterial infection was seen most frequently in adult (mean age 7.4 years; range 0.6-14 years) neutered male cats (11/20). The most common infections were Mycobacterium microti (6/20) and Mycobacterium bovis (6/20). CT abnormalities were most commonly seen in the thorax, consisting of bronchial (9/20), alveolar (8/20), ground glass (6/20) or structured interstitial (15/20) lung patterns, which were often mixed. Tracheobronchial, sternal and cranial mediastinal lymphadenomegaly were common (16/20). Other abnormalities included abdominal (8/13) or peripheral (10/18) lymphadenomegaly, hepatosplenomegaly (7/13), mixed osteolytic/osteoproliferative skeletal lesions (7/20) and cutaneous or subcutaneous soft tissue masses/nodules (4/20). CONCLUSIONS AND RELEVANCE: CT of feline mycobacteriosis shows a wide range of abnormalities, often involving multiple organ systems and mimicking many other feline diseases. Mycobacteriosis should be considered in the differential diagnosis of thoracic, abdominal and skeletal disorders in cats.

Erratum: Vitamin D status in cats with feline immunodeficiency virus.

[This corrects the article DOI: 10.1002/vms3.11.].

Vitamin D status predicts 30 day mortality in hospitalised cats.

Vitamin D insufficiency, defined as low serum concentrations of the major circulating form of vitamin D, 25 hydroxyvitamin D (25(OH)D), has been associated with the development of numerous infectious, inflammatory, and neoplastic disorders in humans. In addition, vitamin D insufficiency has been found to be predictive of mortality for many disorders. However, interpretation of human studies is difficult since vitamin D status is influenced by many factors, including diet, season, latitude, and exposure to UV radiation. In contrast, domesticated cats do not produce vitamin D cutaneously, and most cats are fed a commercial diet containing a relatively standard amount of vitamin D. Consequently, domesticated cats are an attractive model system in which to examine the relationship between serum 25(OH)D and health outcomes. The hypothesis of this study was that vitamin D status would predict short term, all-cause mortality in domesticated cats. Serum concentrations of 25(OH)D, together with a wide range of other clinical, hematological, and biochemical parameters, were measured in 99 consecutively hospitalised cats. Cats which died within 30 days of initial assessment had significantly lower serum 25(OH)D concentrations than cats which survived. In a linear regression model including 12 clinical variables, serum 25(OH)D concentration in the lower tertile was significantly predictive of mortality. The odds ratio of mortality within 30 days was 8.27 (95% confidence interval 2.54-31.52) for cats with a serum 25(OH)D concentration in the lower tertile. In conclusion, this study demonstrates that low serum 25(OH)D concentration status is an independent predictor of short term mortality in cats.

Vitamin D status in cats with feline immunodeficiency virus.

Feline immunodeficiency virus (FIV) is a lentivirus that can lead to a syndrome of acquired immune dysfunction. Infected cats often remain asymptomatic for several years before immune dysfunction leads to an increased risk for the development of systemic diseases, neoplasia and opportunistic infections. FIV is structurally related to human immunodeficiency virus (HIV) and the pathogenesis of FIV-related disease is similar to that seen in HIV-infected patients. Observational studies have documented an association between low plasma vitamin D and HIV infection. Vitamin D status has been shown to be associated with HIV-related disease progression, morbidity and mortality. The objective of this study was to examine the hypothesis that vitamin D status, as assessed by serum 25-hydroxyvitamin D [25(OH)D] concentrations, are lower in cats with FIV infection compared to healthy control cats. Serum 25(OH)D concentrations were measured in 20 healthy cats, 39 hospitalized ill cats and 59 cats infected with FIV. Cats which were FIV infected had significantly lower 25(OH)D concentrations compared to healthy control cats. Serum 25(OH)D concentrations were not significantly different between FIV-infected cats and hospitalized ill cats. Further investigations are warranted to determine whether vitamin D status influences the prognosis of cats infected with FIV.

Assessment of five formulae to predict post-transfusion packed cell volume in cats.

This retrospective study aimed to identify the most accurate formula for estimating the increase in packed cell volume (PCV) after whole blood transfusion of cats, as several formulae have been reported but not validated. Forty cats, of varying breeds and gender, were included from two referral institutions after database searches over a 13 year period. Five formulae were used to calculate an estimated post-transfusion PCV based on the re-working of formulae for determining the volume of donor blood to be transfused; three formulae were derived from those previously reported in the feline literature and two from human paediatric medicine, where a similar mean blood volume has been described. Cats were subdivided into two groups, the first consisting of 17 cats with non-regenerative anaemia and the second consisting of 23 cats with ongoing losses such as haemolysis and haemorrhage; it was hypothesised that formulae could be more accurate for group 1 cats, whereas formulae applied to group 2 cats could have overestimated the post-transfusion PCV. Bland-Altman analysis was performed for all cats to compare the actual increase in PCV with the calculated increase for the five formulae. Formula 1 (PCV % increase = volume of blood transfused in ml/2 × bodyweight in kg) performed best overall and is easy to calculate; however, no single formula was highly accurate at predicting the PCV increase after whole blood transfusion in cats and, owing to the wide confidence intervals, these formulae should be applied judiciously in the clinical setting.

Radiographic findings in cats with mycobacterial infections.

This study describes radiographic changes associated with mycobacterial infection in 33 domestic cats confirmed by culture or interferon-gamma testing. Infection was seen most frequently in adult (average age 5.7 years; range 1.5-12 years), non-pedigree (87%; 27/31), neutered male cats (69%; 22/32). The most common infections were Mycobacterium microti (60%; 18/30) and Mycobacterium bovis (37%; 11/30); Mycobacterium avium and Mycobacterium malmoense were infrequently cultured (3% of each; 1/30). Radiographs were available for the thorax (24 cats), abdomen (eight), appendicular skeleton (11) and head (three). Radiographic changes affected the thorax most commonly, consisting of bronchial (46%; 11/24), alveolar (38%; 9/24), nodular unstructured interstitial (38%; 9/24) or unstructured interstitial (25%; 6/24) lung patterns, which were often mixed. Perihilar or sternal lymphadenopathy were common (42%; 10/24), particularly perihilar lymphadenopathy (25%; 6/24). Skeletal changes were found in the distal antebrachium (three), pes (two), maxilla, scapula, spine, manus, femur, and tarsus (one each). Changes were typically osteolytic (73%; 8/11), often permeative osteolytic (64%; 7/11). Osteoproliferative changes were seen in three cats and soft tissue swelling in five cats, which were adjacent to the bony abnormality in four cats. Other changes included submandibular soft tissue swelling, marked aortic, aortic root and brachiocephalic trunk calcification, and soft tissue swelling with calcification in the distal antebranchium which was not involving bone. Abdominal changes were uncommon (seen in 2/8 cats) and consisted of hepatomegaly and hepatosplenomegaly. In summary, radiographic changes were varied, no lesion was pathognomic for mycobacterial infection, and pathology was seen most commonly in the thorax.

Plasma concentrations of natriuretic peptides in normal cats and normotensive and hypertensive cats with chronic kidney disease.

OBJECTIVES: To determine if natriuretic peptide concentrations are increased in cats with systemic hypertension and/or chronic kidney disease (CKD). ANIMALS: 22 normal cats, 13 normotensive cats with mild-moderate CKD (NT-CKD), 15 hypertensive cats with mild-moderate CKD (HT-CKD) and 8 normotensive cats with severe CKD (NT-CKD-severe). METHODS: N-terminal pro-B-type (NT-proBNP) and pro-A-type (NT-proANP) natriuretic peptides were measured in plasma samples from all cats using commercially available assays and concentrations in the normal and diseased groups compared using non-parametric statistical tests. Spearman's rank correlation was used to test for an association between natriuretic peptide and creatinine concentrations. RESULTS: NT-proANP was significantly higher in the NT-CKD-severe than the normal group of cats (P=0.006) but there were no other differences between groups. NT-proBNP concentrations were significantly higher in the HT-CKD group than both the normal (P<0.001) and the NT-CKD (P<0.001) groups. NT-proBNP concentrations were also higher in the NT-CKD-severe (P<0.001) and the NT-CKD (P=0.005) groups than the normal group. NT-proANP but not NT-proBNP was significantly and positively associated with plasma creatinine concentration. CONCLUSIONS: Measurement of NT-proBNP shows promise as a diagnostic marker for systemic hypertension in the cat. Its concentration is not significantly increased in cats with mild-moderate normotensive CKD.