Use of the urine cortisol: creatinine ratio to monitor treatment response in dogs with pituitary-dependent hyperadrenocorticism.

OBJECTIVE: To determine the usefulness of measuring urine cortisol:creatinine ratio (UCCR) as a means of monitoring response to mitotane treatment in dogs with pituitary-dependent hyperadrenocorticism (PDH). DESIGN: Case series. ANIMALS: 51 clinically normal dogs and 21 dogs with PDH. PROCEDURE: The reference range for the UCCR was determined by measuring the ratio in 51 clinically normal dogs. The usefulness of measuring UCCR in evaluating response of 21 dogs with PDH to treatment with mitotane was evaluated by comparing ACTH-stimulated blood cortisol concentrations with UCCR at the end of the induction phase of treatment (13 dogs) and during the maintenance phase of treatment (21). RESULTS: UCCR was not useful for identifying dogs with inadequate adrenal reserves at the end of the induction phase of treatment or during the maintenance phase. The UCCR was useful for identifying dogs in which control of cortisol secretion was not adequate. CLINICAL IMPLICATIONS: UCCR should not be used for evaluation of dogs during the induction phase of treatment, because the potential consequences of not identifying dogs with inadequate adrenal reserves are great. The UCCR may be useful as an adjunct means of monitoring treatment response during the maintenance phase of treatment. However, the ACTH stimulation test remains a necessary component when monitoring response to treatment in dogs with PDH receiving mitotane.

One-year follow-up evaluation of magnetic resonance imaging of the brain in dogs with pituitary-dependent hyperadrenocorticism.

OBJECTIVE: To evaluate magnetic resonance imaging (MRI) brain scans of dogs with pituitary-dependent hyperadrenocorticism (PDH) and no signs of CNS dysfunction 1 year after diagnosis and initial MRI. DESIGN: Prospective study of surviving dogs from a previous study. ANIMALS: 13 dogs underwent MRI of the brain at the time that PDH was diagnosed and prior to treatment. At that time, none of the dogs had clinical signs suggestive of an intracranial mass. Approximately 1 year after diagnosis and MRI, the brain was again evaluated by MRI. RESULTS: On the initial MRI scan, 5 of the 13 dogs had normal findings, and 8 had evidence of a mass (tumor) in the area of the pituitary gland. Of the 5 dogs that had no visible pituitary mass on the initial MRI scan, 3 had a normal MRI brain scan 1 year later. Of the 5 dogs that had no visible pituitary mass on initial MRI scan, 2 had a visible pituitary mass at 1 year. The 8 dogs that had a visible mass on the initial MRI brain scan had easily identified pituitary masses on the second MRI scan. Of these 8 dogs, 4 had no apparent change in pituitary mass size, and 4 had obvious increase in vertical height of the pituitary mass. Of the 4 dogs, 2 developed signs of neurologic dysfunction within 1 year after diagnosis of PDH, presumably attributable to that mass. Of the 13 dogs, 12 were treated with mitotane soon after completion of the initial MRI scan. Sensitivity to mitotane and initial pituitary mass size or growth were not correlated. Of the 13 dogs evaluated initially and 1 year after diagnosis, 10 had pituitary masses identified on MRI brain scans. CLINICAL IMPLICATIONS: The incidence of visible pituitary masses among dogs with PDH at the time of or within a year of diagnosis was > 75%. In 2 dogs, signs of CNS dysfunction developed within 1 year of PDH diagnosis when pituitary masses were > or = 10 mm.

Effect of lente insulin for treatment of diabetes mellitus in 12 cats.

Ultralente insulin has replaced protamine zinc insulin as the treatment of choice in treatment of diabetes mellitus in cats. There is variability in effectiveness of ultralente insulin and problems with glycemic control develop in some cats. Alternative insulin preparations are sought when ultralente insulin is ineffective. Twelve cats with insulin-dependent diabetes mellitus were treated with lente insulin. Clinical signs improved in 8 cats given lente insulin every 12 hours. Lente insulin was ineffective in 4 cats. Three of these cats were subsequently found to have an insulin resistant disorder. In 1 cat, lente insulin was ineffective because of short duration of action. Lente insulin is a viable treatment alternative when ultralente insulin is ineffective in achieving glycemic control. Ultralente insulin is still the insulin of choice for the initial treatment of diabetes in cats, because of the potential to establish glycemic control with once-a-day treatment.

Magnetic resonance imaging of the brain in dogs with recently diagnosed but untreated pituitary-dependent hyperadrenocorticism.

Magnetic resonance imaging was used to determine the prevalence of visible pituitary masses in 21 dogs with recently diagnosed and untreated pituitary-dependent hyperadrenocorticism. All dogs had clinical signs and routine database values (CBC, serum biochemical panel, and urinalysis) consistent with a diagnosis of hyperadrenocorticism, and none had clinical signs suggestive of an intracranial mass. Each dog had plasma cortisol concentrations after adrenocorticotropic hormone administration or low-dose dexamethasone administration consistent with hyperadrenocorticism. Pituitary-dependent hyperadrenocorticism was confirmed by the finding of 2 equal-size adrenal glands on abdominal ultrasonography and by results of plasma endogenous adrenocorticotropic hormone concentration and high-dose dexamethasone suppression testing. Sagittal and transverse T1-weighted magnetic resonance images of the brain were obtained before and after IV administration of gadopentenate dimeglumine. Eleven dogs had visible masses, ranging in size from 4 to 12 mm at greatest vertical height. Mean age and body weight of dogs with a visible pituitary mass was not significantly different from dogs without a visible mass. There was no significant difference in endocrine test results when comparing dogs with a visible pituitary mass to dogs without. The prevalence of visible pituitary masses in dogs with pituitary-dependent hyperadrenocorticism was greater than suggested by the prevalence of clinical neurologic signs.

Magnetic resonance imaging for diagnosis of pituitary macrotumors in dogs.

The value of magnetic resonance imaging (MRI) for the evaluation of dogs with pituitary-dependent hyperadrenocorticism (PDH) and CNS signs was assessed. Magnetic resonance imaging of the brain was performed in 13 dogs with PDH and neurologic signs. The diagnosis of PDH was made on the basis of results of adrenocortical function tests and abdominal ultrasonography, in conjunction with appropriate history, clinical signs, and clinicopathologic alterations. Eight dogs had been treated with the adrenocorticolytic agent, mitotane, for 1 to 30 months before the development of neurologic signs. Prior to MRI, each dog had progressive neurologic signs that could not be attributed to hypocortisolism or mitotane toxicosis. The neurologic signs most frequently detected were disorientation and ataxia. Mean age of dogs at the time neurologic signs developed was 9.5 years. Sex predilection was not detected; however, most were large-breed dogs, with 11 of the 13 dogs weighing more than 20 kg. A large mass in the pituitary gland, suprasellar region, or both was easily identified on the magnetic resonance images of each dog. The masses ranged from 8 to 24 mm in size. Expansion of tumors into the suprasellar region and compression of structures adjacent to the pituitary gland were readily detected by MRI. Contrast enhancement did not improve tumor identification, but did enable better delineation between tumor and surrounding structures. After the diagnosis of a macrotumor was made by MRI, radiotherapy was initiated in 9 dogs and was successfully completed in 6. Three dogs had a relapse of neurologic signs 8, 11, and 26 months after radiotherapy was completed.(ABSTRACT TRUNCATED AT 250 WORDS)