Physiological Assessment of the Health and Welfare of Domestic Cats-An Exploration of Factors Affecting Urinary Cortisol and Oxytocin

Physiological samples are beneficial in assessing the health and welfare of cats. However, most studies have been conducted in specialized environments, such as shelters or laboratories, and have not focused on cats living in domestic settings. In addition, most studies have assessed physiological stress states in cats based on cortisol, and none have quantified positive indicators, such as oxytocin. Here, we collected urine samples from 49 domestic cats and quantified urinary cortisol, oxytocin, and creatinine using ELISA. To identify factors influencing hormone levels, owners responded to questionnaires regarding their housing environment, individual cat information, and the frequency of daily interactions with their cats. Using principal component analysis, principal component scores for daily interactions were extracted. These results showed that the frequency of tactile and auditory signal-based communication by owners was positively correlated with the mean concentration of oxytocin in the urine. Additionally, this communication was more frequent in younger cats or cats that had experienced a shorter length of cohabitation with the owner. However, no factors associated with urinary cortisol concentration were identified. Our study indicates that interactions and relationships with the owner influence the physiological status of cats and suggests that oxytocin is a valuable parameter for assessing their health and welfare.

Feline plasma adrenocorticotropic hormone: validation of a chemiluminescent assay and concentrations in cats with hypercortisolism, primary hypoadrenocorticism and other diseases

OBJECTIVES

The aims of this study were to validate a commercially available chemiluminescent assay for measurement of feline plasma adrenocorticotropic hormone concentration (ACTH), to determine the normal reference interval (RI) of plasma ACTH in healthy cats, to assess plasma ACTH in cats with naturally occurring hypercortisolism (HC), primary hypoadrenocorticism (PH) and other diseases (OD), and to evaluate the effect of aprotinin on plasma ACTH degradation.

METHODS

Forty healthy cats, 10 with HC, 11 with PH and 30 with OD, were included. The chemiluminescent enzyme immunometric assay was evaluated by measurement of intra-assay precision, interassay precision and linearity. The RI for plasma ACTH in healthy cats was established using robust methods. Plasma ACTH of samples collected with and without aprotinin, stored at 4°C and assayed over a 6-day period, was measured.

RESULTS

The intra-assay coefficients of variance (CVs) ranged from 2.7% to 4.3% and interassay CVs from 3.3% to 10.7%. Dilution studies showed excellent accuracy (R2 >0.99). The RI for plasma ACTH in healthy cats was 32-370 pg/ml. Plasma ACTH was not significantly different between healthy cats and the OD group. Cats with pituitary-dependent hypercortisolism (PDH) and PH had significantly higher plasma ACTH than the other groups. Plasma ACTH did not show significant differences when samples collected with and without aprotinin were compared.

CONCLUSIONS AND RELEVANCE

The Immulite chemiluminescent assay is a valid technique for measuring plasma ACTH in cats and the RI of plasma ACTH is quite wide. Owing to the low overlap between healthy or OD cats and cats with HC or PH, the measurement of plasma ACTH appears to be useful and should be included in the diagnostic work-up when HC or PH are suspected. Furthermore, the measurement of plasma ACTH may be an accurate test for differentiating PDH from adrenal-dependent hypercortisolism.

Feline comorbidities: Recognition, diagnosis and management of the cushingoid diabetic

PRACTICAL RELEVANCE

Diabetes mellitus (DM) is a common feline endocrinopathy, and is often driven by underlying insulin resistance with associated pancreatic beta (β)-cell dysfunction. Although spontaneous hyperadrenocorticism (HAC) with hypercortisolemia (hypercortisolism) is relatively uncommon in cats, it is a well-established cause of insulin resistance and is routinely associated with DM in this species.

CLINICAL CHALLENGES

Many of the clinical signs associated with feline HAC are subtle and may be attributed to concurrent DM or the aging process. Failure to recognize HAC in the diabetic cat can impact patient wellbeing and predispose the patient to progressive compromise. Unfortunately, it can be difficult to establish a diagnosis of HAC, as test results may be influenced by poor diabetic regulation, and protocols are different to those used in canine patients. Treatment options depend on the underlying cause, and often require careful, ongoing assessment and modulation of both adrenal function and insulin requirements. However, various approaches have been shown to either improve glycemic control in cats with sustained insulin dependence, or facilitate diabetic remission.

EVIDENCE BASE

This review summarizes the current literature on feline HAC, with a particular focus on cats with concurrent DM. The clinical findings that suggest HAC are discussed, along with an outline of diagnostic options and their limitations. Published outcomes for various medical options, surgical procedures and radiation therapy are provided. The authors also share their thoughts on the safe and effective management of cats with HAC and DM, with an emphasis on the anticipation and recognition of changing insulin requirements.

Methods of Assessment of the Welfare of Shelter Cats: A Review

At any moment, there are millions of cats housed in foster care facilities for abandoned and stray animals for various reasons worldwide. Care, management and regulation among these facilities differ. Moreover, shelters can never substitute the full comfort of a good home for the animal, and the welfare of cats in shelters is a subject of discussion in many respects. Cats are animals sensitive to changes; for most of them, placement in a shelter is a stressful experience because of changes in routine, environment and the presence of other animals. Stress is reflected in changes in behaviour, causes fluctuations in physiological values and disrupts the immune system, which is a predisposition to the development or reactivation of disease. Evaluation of the presence and intensity of negative impacts is possible through the use of evaluation tools based on indicators that help set the environment and management of keeping so as to disrupt the quality of life as little as possible. Although a comprehensive and valid welfare tool that would evaluate animal-based and at the same time resource-based (or management-based) indicators of cats in shelters is not currently available, it is possible to use partial evaluation of individual welfare indicators to assess welfare. This review aims to provide the readers with an insight into current options of assessment of the welfare of cats in shelters with an emphasis on behavioural, physiological and health indicators with an application in both practical and scientific contexts.

Peculiarities of feline hyperadrenocorticism: Update on diagnosis and treatment

Practical relevance: Hyperadrenocorticism (HAC) is a relatively uncommon endocrinopathy of older cats, with a mean age at diagnosis of 10 years. In addition to pituitary-dependent and adrenal-dependent hypercortisolism, clinical signs of HAC can result from adrenal sex steroid-producing tumours. Clinical challenges: While HAC in cats has many similarities to canine HAC, there are key differences in presentation, diagnosis and response to therapy. Most, but not all, cats with HAC have concurrent diabetes mellitus, which is often insulin resistant. Up to a third of cats with HAC have extreme skin fragility and are at high risk of debilitating iatrogenic skin tears during diagnostic or therapeutic interventions. Infections of the skin and nail beds, and urinary, respiratory and gastrointestinal tract, secondary to cortisol-induced immune suppression, are also common. Cats respond differently to dogs to adrenal function tests including adrenocorticotropic hormone (ACTH) stimulation and dexamethasone suppression tests; a 10-fold higher dose of dexamethasone is recommended in cats to screen for HAC. Curative treatment options include adrenalectomy or transsphenoidal hypophysectomy. Radiation or medical treatment may improve clinical signs. The response to mitotane therapy is poor. While trilostane is the medical treatment of choice based on retrospective studies, investigations into the pharmacokinetics of this drug in cats are lacking. Global importance: Feline HAC occurs worldwide and is not associated with any purebreed predisposition. Although uncommon, adrenal sex steroid-producing tumours have a higher prevalence in cats than in dogs. Evidence base: The information in this review is drawn from over 180 reported cases of feline HAC. Reports investigating clinical presentation, clinicopathological findings and treatment outcomes are observational, retrospective multiple case series (EBM grade III) or single case reports (EBM grade IV). While most endocrine testing studies for diagnosis are cohort controlled analytical studies (EBM grade III), prospective, randomised, placebo-controlled studies have been performed (EBM grade I).

Adrenal function in cats with cholestatic liver disease

Cats with cholestatic liver disease experience significant morbidity and mortality when they undergo invasive procedures under anesthesia. Although inadequate adrenal response might account for these outcomes, adrenal function in cats with cholestatic liver disease has not been documented, to our knowledge. The goal of our study was to describe adrenal function in these cats. Twenty-seven cats with a serum bilirubin >230 µmol/L (3 mg/dL) and serum alanine aminotransferase >2 times the upper limit of normal had pre– and 60-min post–adrenocorticotropic hormone (ACTH) cortisol analysis after administration of 5 µg/kg cosyntropin intravenously. The change in cortisol concentrations (delta cortisol) was calculated. Pre- and post-ACTH cortisol concentrations were compared to reference values. Pre-ACTH, post-ACTH, and delta cortisol values were compared between cats surviving to discharge or for 30 d postdischarge. Mean pre-ACTH cortisol levels (205 ± 113 nmol/L [7.4 ± 4.2 µg/dL]) and post-ACTH cortisol levels (440 ± 113 nmol/L [15.9 ± 4.1 g/dL]) in cholestatic cats were significantly greater than reference values in clinically normal cats. There was no association of pre- or post-ACTH cortisol with survival. Cats with a delta cortisol <179 nmol/L (6.5 µg/dL) were more likely to be non-survivors at 30 d post-discharge ( p = 0.037) than cats with delta cortisol >179 nmol/L (6.5 µg/dL). Results indicate that cats with cholestasis have high basal and ACTH-stimulated cortisol values. A delta cortisol <179 nmol/L (6.5 µg/dL) defines a population of cats that have decreased 30-d survival.

Trilostane therapy for treatment of spontaneous hyperadrenocorticism in cats: 15 cases (2004-2012)

BACKGROUND

Medical treatment with trilostane improves clinical signs, causes unclear insulin requirement changes, and variable survival times in cats.

OBJECTIVES/HYPOTHESIS

To characterize the long-term efficacy of trilostane in treating cats with hyperadrenocorticism (HAC).

ANIMALS

Fifteen client-owned cats with spontaneous HAC.

METHODS

Multicenter descriptive retrospective study with a search performed on all medical records for cats diagnosed with spontaneous HAC.

RESULTS

Clinical signs (13 of 15 cats) and ACTH stimulation testing results (13 of 15) improved with trilostane therapy. Diabetes mellitus was reported in 9/15 cases. Insulin requirements decreased by 36% within 2 months in 6/9 diabetic cats. Median survival time was 617 days for all cats (range 80-1,278 days). Complications included weight loss, urinary tract infections, chronic kidney disease, seizures, and recurrent pancreatitis. Hypocortisolemia was documented in 1 case. Cause of death occurred as a result of nonadrenal or nondiabetic illnesses (renal failure, seizures [caused by hypoglycemia or unknown]), or lymphoma.

CONCLUSIONS AND CLINICAL IMPORTANCE

Trilostane ameliorates clinical signs of HAC in cats, is tolerated well in the long term, and can lead to improved regulation of diabetes.

The effect of ACTH stimulation on cortisol and progesterone concentrations in intact and ovariohysterectomized domestic cats

The objective was to evaluate the adrenocortical capacity for cortisol and progesterone production in female cats, both while intact and after ovariohysterectomy. Five privately owned female cats, 1-3 years old, were used in two trials while intact at an inactive stage of the cycle, and again in two trials, 2 weeks after ovariohysterectomy. The four trials were: intact saline injection control trial; intact ACTH injection (0.125 mg); ovariohysterectomized saline injection control trial; and ovariohysterectomized ACTH injection. Blood samples were obtained by an indwelling cephalic vein catheter at -30 and 0 min (immediately before injections) and at 60, 90, 120 and 180 min after injection. The mean basal pre-treatment concentrations of cortisol in the intact and ovariohysterectomized cats were 33 +/- 19 and 32 +/- 19 nmol/L, respectively; the corresponding values for progesterone were 1.1 +/- 0.6 and 0.7 +/- 0.6 nmol/L, respectively. Saline did not alter the serum cortisol or progesterone concentrations. In contrast, both cortisol and progesterone were elevated after ACTH, with peak values at 90 min and returned to basal levels at approximately 180 min. There was a positive correlation between cortisol and progesterone concentrations (r = 0.8, P < 0.05). In some instances, the procedure used to restrain the cats during blood collection induced increases in cortisol and progesterone of the same magnitude as when the ACTH was administered; these effects of restraint could alter the results of assisted reproduction efforts.

Iatrogenic hyperadrenocorticism in a cat following a short therapeutic course of methylprednisolone acetate

Iatrogenic hyperadrenocorticism (or iatrogenic Cushing's syndrome) is an adrenal disorder that may result from long-term administration of glucocorticoids for therapeutic purposes, most often given to treat allergic or immune-mediated disorders. Prolonged treatment with synthetic glucocorticoids can suppress hypothalamic corticotrophin releasing hormone and plasma adrenocorticotrophic hormone (ACTH), thus causing a functional inactivity of the adrenal cortex. The result is a clinical syndrome of hyperadrenocorticism but with basal and ACTH-stimulated plasma cortisol concentrations that are consistent with spontaneous hypoadrenocorticism (Addison's disease). Whilst iatrogenic hyperadrenocorticism is relatively frequent in dogs, the diagnosis of iatrogenic hyperadrenocorticism in cats is very uncommon because this species has been found to be remarkably resistant to prolonged administration of glucocorticoids. To the author's knowledge, there are only two published clinical cases of feline iatrogenic Cushing's syndrome. This report describes a case of iatrogenic hyperadrenocorticism in a cat, and shows how normalisation of the adrenal function was achieved with supportive treatment and withdrawal of glucocorticoid administration.

Hypoadrenocorticism in a cat

Primary hypoadrenocorticism was diagnosed in an eight-year-old neutered male cat. The predominant presenting complaint was dysphagia. Other historical signs included lethargy, weight loss, polydipsia, polyuria, muscle weakness and occasional vomiting. The signs had waxed and waned over the two months before presentation and had improved when the cat was treated with enrofloxacin and prednisolone by the referring veterinarian. On referral, dehydration, depression and poor bodily condition were found on physical examination. Results of initial laboratory tests revealed mild anaemia, hyperkalaemia, hyponatraemia, hypochloraemia and elevations in serum creatinine and creatine kinase. The diagnosis of primary adrenocortical insufficiency was established on the basis of results of an adrenocorticotropic hormone (ACTH) stimulation test and endogenous plasma ACTH determination. Initial therapy for hypoadrenocorticism included intravenous administration of 0.9 per cent saline and dexamethasone, and oral fludrocortisone acetate. Within one week the cat was clinically normal and two years later was still alive and well on fludrocortisone acetate treatment only.

Cortisol response to two different doses of intravenous synthetic ACTH (tetracosactrin) in overweight cats

Fifteen middle-aged to older, overweight cats attending a first-opinion clinic were investigated to rule out hyperadrenocorticism as a cause of their weight problem, using two different protocols for the adrenocorticotropic hormone (ACTH) stimulation test. The cats received intravenous synthetic ACTH (tetracosactrin) at an initial dose of 125 microg; a second test was performed between two and three weeks later, using a dose of 250 microg intravenously. The mean basal serum cortisol concentration was 203 nmol/litre (range 81 to 354 nmol/litre). The highest mean serum cortisol concentration occurred at 60 minutes following the 125 microg dose and at 120 minutes following the 250 microg dose. There was, however, no statistically significant difference between these peak cortisol concentrations attained using either dose of tetracosactrin. A significantly higher mean serum cortisol concentration was attained after the higher dose at the 180 minutes time point, indicating a more prolonged response when compared with the lower dose. The cats were followed up for one year after the initial investigations and none were found to develop hyperadrenocorticism during this time.

A case of feline primary hypoadrenocorticism

A 2-year-old entire female British Shorthair cat was referred to the University of Bristol for investigation of lethargy, weakness, constipation and hypothermia. Clinical examination revealed a profoundly weak, hypovolaemic and hypothermic cat. Serum biochemistry revealed hyponatraemia, hyperkalaemia and hyperphosphataemia and the urine was isosthenuric. Lack of response to exogenous adrenocorticotrophic hormone confirmed a diagnosis of hypoadrenocorticism. Treatment consisted initially of intravenous fluid therapy and subsequently a combination of fludrocortisone and prednisolone per os. At follow-up, 20 months after the initial diagnosis the cat remained stable and free of clinical signs.

Hyperadrenocorticism in six cats

The case records of six cats with hyperadrenocorticism presented to the Department of Clinical Veterinary Medicine, University of Cambridge, over an 11-year period were reviewed. Signalment and clinical signs were similar to previous reports but, in contrast to other reports, only three cats had diabetes mellitus on presentation. Abdominal radiographs revealed an adrenal mass in one case, obesity in all cases but no hepatomegaly. The adrenal glands were identified ultrasonographically in three out of six cases. Clinicopathological findings were non-specific. The diabetic cats had a significantly lower serum potassium concentration than the non-diabetic cats (P < 0.05). Results of adrenocorticotrophic hormone (ACTH) stimulation tests were supportive of a diagnosis of hyperadrenocorticism in the five cats in which they were performed. Five cats had pituitary-dependent hyperadrenocorticism (PDH) and one had an adrenal tumour. Differentiation between the two forms of hyperadrenocorticism was possible preoperatively in five out of six cats. Adrenal histopathology confirmed hyperplasia in four cats and adenocarcinoma in one cat. Three cats with PDH underwent bilateral adrenalectomy and two of these cats had low, flat ACTH stimulation tests postoperatively and survived for significant periods. The cat with an adrenal tumour underwent partial unilateral adrenalectomy, maintained a positive ACTH stimulation test postoperatively and was euthanased one week after surgery.

Plasma cortisol levels in captive wild felines after chemical restraint

Eight Panthera onca (Po), 13 Felis concolor (Fc), 7 Felis yagouaroundi (Fy), 7 Felis tigrina (Ft) and 5 Felis pardalis (Fp) specimens from São Paulo State zoos were used. All animals were restrained with darts containing 10 mg/kg ketamine and 1 mg/kg xylazine. Venous blood samples were collected as soon as possible (within 15-20 min) and serum was frozen until the time for cortisol quantification. Cortisol was determined using a solid phase radioimmunoassay with an intra-assay coefficient of 8.51%. Data were analyzed statistically by the Kruskal-Wallis test, followed by Dunn's multiple comparisons test, and the one-sample t-test, with the level of significance set at P < 0.05. Data are reported as means +/- SEM. Cortisol levels differed among the captive felines: Po = 166 +/- 33a, Fc = 670 +/- 118b, Fy = 480 +/- 83b, Ft = 237 +/- 42ab, Fp = 97 +/- 12a nmol/l (values followed by different superscript letters were significantly different (P < 0.001)). Since most of the veterinary procedures on these species involve chemical restraint, these results show the necessity of preventive measures in order to minimize the effect of restraint stress on more susceptible species.

Adrenal disorders in cats

Although adrenal disorders are uncommon in cats, they are being recognized with increasing frequency. The low incidence and unique characteristics of adrenal disease in cats often make the diagnosis and treatment of these disorders challenging. This article summarizes information on the diagnosis and treatment of feline adrenal disorders, including hyperadrenocorticism, hypoadrenocorticism, pheochromocytoma, and hyperaldosteronism.