This retrospective study describes the clinical progression of 12 cats with pituitary tumours treated with a coarse fractionated radiation protocol delivering a total dose of 37 Gy in five once weekly fractions. A pituitary macrotumour was identified in all 12 cats: 4 with neurological signs only and 8 with insulin-resistant diabetes mellitus secondary to acromegaly. One of the cats with central neurological signs died before completing the radiotherapy course; the remaining three had partial or complete remissions of their central neurological signs. Of the cats with unstable diabetes mellitus, five no longer required insulin therapy, one required less insulin and two became stable. The overall median survival time was 72.6 weeks; four cats died from related causes, two from unrelated problems and six remain alive. Radiation therapy is confirmed as an effective treatment for feline pituitary tumours, giving prolonged survival and control of both paraneoplastic and mass effect signs.

The use of insulin-like growth factor 1 assays in the diagnosis and subsequent monitoring after radiotherapy of an acromegalic cat with a secretory pituitary adenoma and secondary insulin-resistant diabetes mellitus is described. Diabetes resolved, and exogenous insulin was no longer required for the maintenance of normoglycaemia 10 months after completion of a course of hypofractionated radiotherapy. However, insulin-like growth factor 1 remained elevated, and the cat's size and appetite continued to increase. It is suggested that radiotherapy may decrease growth hormone concentration to a level such that diabetogenic effects are no longer evident but not to a level required to decrease insulin-like growth factor 1 secretion.

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.

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.

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