Carmel T. Mooney

Trilostane treatment of 78 dogs with pituitary-dependent hyperadrenocorticism

The efficacy of trilostane in the treatment of canine pituitary-dependent hyperadrenocorticism (PDH) was evaluated in 78 dogs with the condition which were treated for up to three years. The drug appeared to be well tolerated by almost all the dogs, and only two developed clinical signs and biochemical evidence of hypoadrenocorticism. Polyuria and polydipsia completely resolved in 70 per cent of the dogs that had these problems, and skin changes resolved in 62 per cent of the dogs that had skin abnormalities. There was a significant reduction (P<0.001 in each case) in both the mean basal and post-adrenocorticotrophic hormone (ACTH) cortisol concentrations after a mean of 12.3 days of treatment. The post-ACTH cortisol concentration decreased to less than 250 nmol/litre in 81 per cent of the dogs within one month of the start of treatment and in another 15 per cent at some later time. The median survival time of the 26 dogs which died was 549 days, and 51 of the dogs were alive at the completion of the study. One was lost to follow up after 241 days treatment.

Muscular dystrophy with truncated dystrophin in a family of Japanese Spitz dogs

Muscular dystrophy was diagnosed in seven male Japanese Spitz dogs with clinical signs of slowly progressive exercise intolerance, generalized weakness, myalgia, difficulty chewing and dysphagia. Serum creatine kinase (CK) concentrations were markedly elevated. Histopathology showed degeneration and regeneration of muscle, consistent with a dystrophic phenotype. Immunohistochemical staining for dystrophin and related proteins showed no staining with a monoclonal antibody against the rod domain of dystrophin but near-normal staining with an antibody against the C terminus. Immunoblot analysis in two affected dogs showed a truncated dystrophin protein of approximately 70-80 kDa. The severity of disease showed that this fragment was not large enough to protect from the dystrophic process.

Diagnosis and management of diabetes mellitus in five cats with somatotrophic abnormalities.

The clinical findings and management of five cats with abnormalities consistent with acromegaly were examined retrospectively. Growth hormone (GH) concentrations were elevated in four cats. In one, a minimal elevation of GH was accompanied by a marked elevation in insulin-like growth factor-1 (IGF-1). Insulin-like growth factor-1 concentrations supported the diagnosis in three of four cats measured, but was not elevated initially in one cat, despite a markedly elevated GH concentration. These findings suggest that elevated IGF-1 concentrations are a reliable indicator of acromegaly, but that values within the reference range do not exclude such a diagnosis. Clinical signs of acromegaly were similar to those previously reported, although upper respiratory stridor occurred in one cat, and insulin-resistant diabetes mellitus was not a consistent feature. Despite the lack of a widely available definitive treatment for acromegaly, good control of the clinical signs of diabetes mellitus can be achieved for long periods despite high doses of insulin often being required.

Pathogenesis of Feline Hyperthyroidism

Hyperthyroidism is recognised not only as the commonest endocrine disease of domestic cats but as one of the most frequently diagnosed disorders in small animal practice. Prior to its first definitive diagnosis in 1979, there were few reports of pathological abnormalities in feline thyroid glands and only anecdotal reference to clinical signs that may have been caused by hyperthyroidism. Since that time, there has been a marked increase in the frequency of diagnosis of feline hyperthyroidism. It is unlikely that increased awareness and improved diagnostic capabilities alone account for such a dramatic increase in the prevalence of this disease and it has been suggested that hyperthyroidism is truly a new disease of cats. However, this is complicated by a growing cat population, an increased longevity for cats and possibly, a greater propensity to seek veterinary advice. Thyrotoxicosis arises because of the excess production of the active thyroid hormones, triiodothyronine (T3) and/or thyroxine (T4) from an abnormally functioning thyroid gland. To date, much research has been carried out culminating in a wealth of data on clinical manifestations, diagnostic tests and therapeutic options. Histopathologically, functional adenomatous hyperplasia (adenoma) of one (approximately 30% of cases) or more commonly, both (70% of cases) thyroid lobes is known to be the most common abnormality associated with hyperthyroidism while thyroid carcinoma is rare, accounting for less than 2% of cases. However, the

Canine hypothyroidism: A review of aetiology and diagnosis

Abstract Hypothyroidism is recognised as an important endocrine disorder of dogs, and a frequent differential for numerous presenting complaints. Its diagnosis has never been straight forward as results suggestive of hypothyroidism can occur for a variety of reasons in dogs with normal thyroid function (euthyroid). As a consequence, the accurate investigation of hypothyroidism has been hindered by the potential inclusion of a number of cases not truly hypothyroid. In recent years, the development of newer diagnostic tests, e.g. free thyroxine, canine thyroid stimulating hormone, thyroglobulin autoantibodies, has significantly improved our ability to reliably differentiate hypothyroidism from other clinically similar disorders. This has led to a marked increase in our knowledge of the phenotypic, genotypic and aetiological aspects of this disorder in dogs.

Prevalence of and risk factors for feline hyperthyroidism in Hong Kong

A study was conducted to determine the prevalence of and potential risk factors for feline hyperthyroidism in Hong Kong. Serum total thyroxine (T4) was measured in 305 cats aged 10 years and older that presented at various veterinary clinics in Hong Kong. The prevalence of hyperthyroidism (T4>50 nmol/l) within this population was 3.93% and there was no significant difference in prevalence between healthy (3.16%) and sick (4.37%) cats. Older cats (>15 years) were more likely to be affected and domestic shorthair cats were less likely to be diagnosed with hyperthyroidism than the other breeds combined. No specific association between the development of feline hyperthyroidism and food type was observed. The prevalence of feline hyperthyroidism in Hong Kong was less than that reported for most other parts of the world, despite the presence of previously identified risk factors.

Evaluation of the basal and post-adrenocorticotrophic hormone serum concentrations of 17-hydroxyprogesterone for the diagnosis of hyperadrenocorticism in dogs.

Serum concentrations of 17-hydroxyprogesterone and cortisol were measured before and after the administration of exogenous adrenocorticotrophic hormone (AcrH) to three groups of dogs: 27 healthy dogs (group 1), 19 dogs with non-adrenal illness (group 2) and 46 dogs with hyperadrenocorticism (group 3). The median (range) post-AcTH concentrations of 17-hydroxyprogesterone were 5-0 (22.2 to 16.8), 6.9 (2.0 to 36.2) and 14.4 (1.7 to 71) nmol/litre in groups 1, 2 and 3, respectively. There were no significant differences in the basal or post-Acm concentrations of cortisol or 17-hydroxyprogesterone between groups 1 and 2. The post- ACTH concentrations of 17-hydroxyprogesterone in group 3 were significantly (P<0.001) greater than those in groups 1 and 2 combined. The area under the receiver operating curve (ROC) for the post-AcrH concentration of cortisol (0.94) was significantly greater than that for the post-AcTH concentration of 17-hydroxyprogesterone (0.76). Using a two-graph ROc analysis, a cut-off of 8.5 nmol/litre was found to maximise both the sensitivity and specificity of the post-AcTH concentration of 17-hydroxyprogesterone for the diagnosis of hyperadrenocorticism at 71 per cent. With a cut-off of 4.5 nmol/litre the sensitivity increased to 90 per cent but the specificity decreased to 40 per cent; with a cut-off of 16.7 nmol/litre the specificity increased to 90 per cent but the sensitivity decreased to 47 per cent.

Effect of hematocrit on accuracy of two point-of-care glucometers for use in dogs

OBJECTIVE To determine the effect of Hct on blood glucose readings of dogs obtained by use of 2 point-of-care (POC) blood glucometers and a laboratory analyzer. ANIMALS 184 dogs, including 139 Greyhounds. PROCEDURES Venous blood samples collected from 184 dogs with a range of Hcts (measured in EDTA-anticoagulated blood) were immediately analyzed with a handheld glucometer specifically developed for veterinary use and a glucometer developed for use in humans. The remainder of each blood sample was placed in fluoride oxalate tubes, and plasma glucose concentration was measured with a laboratory analyzer. Agreement between results for the POC glucometers and laboratory analyzer and effect of Hct on glucometer accuracy was assessed via regression analysis. RESULTS Significant differences were detected between results of the glucometers and the reference laboratory analyzer. The Hct affected the correlation between results for the glucometers and the laboratory analyzer. Deviations of the glucometers from the reference interval varied with Hct. The glucometer for veterinary use more closely correlated with the glucose concentration when Hct was within or above its reference interval. The glucometer for use in humans more closely approximated laboratory reference glucose concentrations in anemic dogs. CONCLUSIONS AND CLINICAL RELEVANCE Hct had a relevant impact on the correlation between whole blood and plasma glucose concentrations in dogs. Significant variations between results obtained with the 2 glucometers could be critical when interpreting blood glucose measurements or selecting a POC glucometer for an intensive care setting and precise glycemic control in critically ill dogs.

Treatment of 46 cats with porcine lente insulin – a prospective, multicentre study

This prospective, multicentre, non-blinded, open study followed 46 cats with diabetes mellitus during treatment with porcine lente insulin (also known as porcine insulin zinc suspension, Caninsulin®, Intervet) for 16±1 weeks (stabilization phase), with additional monitoring of some cats (n=23) for a variable period. At least three of the following were present at initial presentation: appropriate history of clinical signs consistent with diabetes mellitus, glucosuria, blood glucose greater than 15 mmol/l and fructosamine greater than 380 μmol/l. Insulin treatment was started at a dose rate of 0.25–0.5 IU/kg body weight twice daily, with a maximum starting dose of 2 IU/injection. Twenty-eight of the cats were classed as reaching clinical stability during the study, in 23 of these cats this was during the stabilization phase. Seven cats went into remission during the stabilization phase and one of the cats in week 56. Clinical signs of hypoglycaemia, significantly associated with a dose of 3 units or 0.5 IU/kg or more per cat (twice daily), were observed in nine of the 46 cats during the stabilization phase and concomitant biochemical hypoglycaemia was recorded in most cases. Biochemical hypoglycaemia, recorded in 6% of the blood glucose curves performed during the stabilization phase, was significantly associated with a dose rate of 0.75 IU/kg or more twice daily. This further highlights the need for cautious stepwise changes in insulin dose. The protocol used in the present study is suitable for and easy to use in practice. This study confirmed the efficacy and safety of porcine lente insulin (Caninsulin®) in diabetic cats under field conditions.

Syndrome of inappropriate antidiuretic hormone secretion associated with congenital hydrocephalus in a dog.

A 13-month-old, male bichon frise was examined for the investigation of intermittent seizures, ataxia, abnormal behavior, polyuria, and polydipsia. At presentation, clinical and neurological examinations were unremarkable with the exception of mild truncal ataxia and a domed skull. Severe hyponatremia and hypoosmolality were identified, and following diagnostic testing a diagnosis of the syndrome of inappropriate antidiuretic hormone secretion (SIADH) was made. Magnetic resonance imaging revealed changes consistent with severe hydrocephalus. Water restriction resulted in increased serum osmolality and a reduction in severity of clinical signs. The current case report documents SIADH associated with hydrocephalus in a dog. Structural brain disease should be excluded before a diagnosis of idiopathic SIADH is made.