Increased insulin-like growth factor 1 concentrations in a population of non-diabetic cats with overweight/obesity.

Feline hypersomatotropism (HST) is typically associated with diabetes mellitus (DM), whereas HST without concurrent DM has only been reported in a few cases. Weight gain may be observed in cats with HST. The aims of this study were to evaluate circulating insulin-like growth factor-1 (IGF-1) in non-diabetic cats with overweight/obesity, to screen this population for the presence of HST, and to assess whether there is a correlation between body weight/body condition score (BCS) and serum IGF-1 concentration in overweight/obese cats. In this prospective study, 80 overweight/obese cats from referral centers in Buenos Aires (Argentina) were evaluated. Serum IGF-1 was measured as part of the routine tests for overweight/obesity. Non-diabetic cats were included in the study if they had a BCS>6/9. Twenty-nine cats were classified as overweight (BCS 7/9), whereas 51 were classified as obese (BCS 8-9/9). Median serum IGF-1 concentrations of cats with BCS 7/9, 8/9, and 9/9 were 570 ng/ml (range 123-1456 ng/ml), 634 ng/ml (range 151-1500 ng/ml), and 598 ng/ml (range 284-2450 ng/ml), respectively. There was a positive linear correlation between serum IGF-1 concentrations and body weight (r= 0.24, 95% CI 0.01-0.44 P=0.03), and between IGF-1 and BCS (r= 0.27, 95% CI 0.08-0.44 P=0.004). In total, 8.75% (95% confidence interval 3.6-17.2%) of the cats with overweight/obesity had IGF-1 concentrations >1000 ng/ml. Pituitary enlargement was detected on computed tomography in 4/7 cases. These seven cats showed varying degrees of phenotypic changes consistent with acromegaly. A proportion of 8.75 % of overweight/obese non-diabetic cats from referral centers in Buenos Aires had serum IGF-1 concentration in a range consistent with HST in diabetic cats. Likewise, 5% of overweight/obese cats were likely to be diagnosed with HST, supported by evidence of pituitary enlargement. Serum IGF-1 concentrations were positively correlated with body weight and BCS in this population of cats. This study highlights the relevance of screening different populations of non-diabetic cats to increase the detection of HST/acromegaly.

Effect of storage and single layer centrifugation before cryopreservation on stallion sperm cryosurvival.

The objectives of this study were to evaluate the effect of a short, cooled storage before cryopreservation on sperm progressive motility (PM) and compare the effect of different centrifugation methods on post-thaw PM of stored samples. Semen was diluted in chilling extender and aliquoted in 6 protocols: i) Standard centrifugation (SC) followed by freezing; ii) Single Layer Centrifugation (SLC) followed by freezing; iii) Storage for 8 h/5 °C before SC; iv) Storage for 8 h/5 °C before SLC; v) Storage for 8 h/15 °C before SC; and vi) Storage for 8 h/15 °C before SLC. PM was assessed before centrifugation, after centrifugation, and post-thawing. Stallions were classified as "good freezers" (GF) or "bad freezers" (BF). The PM in samples immediately frozen was greater than in the stored ones (71.98 ± 14.2, 52.91 ± 17.8, 53.93 ± 18.9 for no storage, 5 ºC storage and 15 ºC storage, respectively) (P˂ 0.0001). There was an effect of storage condition (p ˂ 0.0001), centrifugation method (p ˂ 0.0001), and freezability (P=0.0016), with an interaction between them (P= 0.0004), on PM after centrifugation. Post-thaw PM was greater in samples treated by SLC than in samples processed by SC, for all storage conditions (p ˂ 0.05). All BF stallions 'showed post-thaw PM ˂ 30 % when samples were previously stored. Storage at 5 ºC or 15º C for 8 h maintains an appropriate quality in GF stallions. Applying a sperm selection technique as SLC is suggested to improve post-thaw motility, allowing GF straws to be frozen after storage, although BF semen should be prepared by SLC immediately after collection.

Haematology and biochemistry in healthy llamas at sea level.

In the last years, there has been an increasing interest in llamas, not only as part of a productive system, but mostly as companion animals. Most reports regarding clinical biochemistry and haematology include few llamas and details about their health status are not available. The present study aims to provide haematological and biochemical parameters for llamas of known health status. Twenty-three non-pregnant females and seven males that live in Buenos Aires, Argentina (34°36'S, 58°22'W, at sea level) were studied. Llamas were clinically healthy, in good nutritional status. Animals were kept at grass and were fed hay bale or pellets and water ad libitum. Blood samples were collected by jugular venipuncture in spring. Packed cell volume, leucocyte count, differential white cell count, platelets count, urea, creatinine, total proteins, albumin, alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase, glucose, calcium and phosphate were assessed. No significant differences were observed between males and females, except for platelet count and calcium, which was greater in males (P˂0.01). Values obtained for the different parameters were similar to those previously reported, except for monocytes, alkaline phosphatase, glucose and calcium, that were lower and lymphocytes and platelets count, that were higher in this study. In conclusion, different ambient and methodological conditions might affect some parameters. The parameters hereby presented are representative of llama's population living at sea level in South America.

Synchronization of time of development of ovarian follicular waves in South American Camelids.

South American camelids (SAC) are induced ovulating animals. In unmated females, ovarian follicle development occurs in waves of growth and regression, while mating when there is the presence of a mature follicle leads to ovulation. The capacity to respond to an ovulatory stimulus depends on the stage of the follicular wave development. Treatments to control ovarian follicular development have been performed to synchronize timing of wave emergence and development of the dominant follicle at a predictable time. Thus, synchronization of the time of follicular wave development allows for performing fixed time mating or artificial insemination, and superestimulatory treatments for multiple follicule development. Protocols are based on removal of the suppressive effect of the dominant follicle, that can be achieved by physical ablation or by inducing ovulation (with LH or GnRH) or atresia (with progesterone or progestagens alone or combined with estradiol) of this follicle. Differences between treatments should be taken into consideration when choosing a protocol for fixed time mating or artificial insemination, especially when applying the use these technologies for SAC production by commercial enterprises. Furthermore, the objective of applying synchronization protocols should be considered, because not all of these are effective in inhibiting follicular growth before initiation of a superestimulatory treatment for multiple follicle development.

Leptin and IGF1 receptors in alpaca (Vicugna pacos) ovaries.

Folliculogenesis and ovulation are regulated by gonadotrophins and other factors such as Insulin like growth factor 1 (IGF1) and leptin. In various species the presence of IGF1 receptor (IGF1R) and leptin receptor (ObR) has been detected in the ovary, but not in the alpaca. Thus, the aim of the present study was to evaluate the presence of these receptors in this tissue and analyze if the presence of these receptors in the ovary is related to the presence of a corpus luteum (CL) and if abundances, as determined by immunostaining intensity vary with follicle size. The IGF1R and ObR were identified in primary and secondary follicles, granulosa and theca interna cells of tertiary follicles and in CL. There were greater abundances of IGF1R in granulosa cells of tertiary follicles of ovaries without compared with those with CL. In both groups, the immunostaining of granulosa cells was greater than in theca interna cells. The abundance of ObR was greater in primary and secondary follicles, and theca interna cells of tertiary follicles in ovaries with than those without CL. Immunostaining of granulosa cells was greater than theca interna cells only in ovaries without CL. There were no differences in the abundance of ObR and IGF1R between primary and secondary follicles and granulosa cells of tertiary follicles, neither in ovaries with or without CL. The abundance of IGF1R was not correlated with abundance of ObR neither in ovaries with or without CL. These results indicate a possible role for IGF and leptin in ovarian function. Furthermore, these receptors could be regulated by ovarian steroid hormones because abundance of these receptors in ovaries varies depending on whether there is a CL present in the ovary.

Immunohistochemical analysis of the hypothalamic-pituitary-adrenal axis in dogs: Sex-linked and seasonal variation.

This study evaluated sexual dimorphism and seasonal variations in corticotrophs and adrenal zona fasciculata in dogs, as well as the expression of oestrogen receptor alpha (ERα). An immunohistochemical analysis was conducted in pituitaries for ACTH and in adrenal glands for ERα and for the melanocortin-2-receptor (MC2R) in winter and summer. Double immunofluorescence was performed to identify ERα in corticotrophs. Females had a greater proportion of corticotrophs per field (p<0.01), with a greater cellular area and optical density (p<0.001) than males. Optical density of corticotrophs was greater in winter for both sexes (p<0.001). In zona fasciculata, ERα and MC2R expression was greater in females (p<0.001) and was greater in winter (p<0.001). ERα was identified in corticotrophs. This study is the first to demonstrate ERα expression in corticotrophs and the adrenal cortex in dogs, providing evidence for sexual dimorphism and seasonal variations.

Involvement of glucagon-like peptide 1 in the glucose homeostasis regulation in obese and pituitary-dependent hyperadrenocorticism affected dogs.

The incretin glucagon-like peptide 1 (GLP-1) enhances insulin secretion. The aim of this study was to assess GLP-1, glucose and insulin concentrations, Homeostatic Model Assessment (HOMA insulin sensitivity and HOMA ß-cell function) in dogs with pituitary-dependent hyperadrenocorticism (PDH), and compare these values with those in normal and obese dogs. The Oral Glucose Tolerance Test was performed and the glucose, GLP-1 and insulin concentrations were evaluated at baseline, and after 15, 30, 60 and 120 minutes. Both basal concentration and those corresponding to the subsequent times, for glucose, GLP-1 and insulin, were statistically elevated in PDH dogs compared to the other groups. Insulin followed a similar behaviour together with variations of GLP-1. HOMA insulin sensitivity was statistically decreased and HOMA ß-cell function increased in dogs with PDH. The higher concentrations of GLP-1 in PDH could play an important role in the impairment of pancreatic ß-cells thus predisposing to diabetes mellitus.

Interleukin-6 and insulin incrase and nitric oxide and adiponectin decrease in blind dogs with pituitary-dependent hyperadrenocorticism.

In this study, two populations of dogs with pituitary dependent hypercortisolism (PDH) were compared over a 2-year period. One group had normal vision (Group A, n=27) and one group was blind (Group B, n=20). Group B was characterised by the rapid appearance of the clinical signs of PDH that precede blindness. We found increases in pre-adrenocorticotropic hormone cortisol (P=0.002), IL-6 (P=0.0001), insulin, and insulin sensitivity (detected with the Homeostatic Model Assessment, P<0.0001) in Group B but not in Group A. The nitric oxide (NO) and the total adiponectin concentrations decreased (P=0.0001 and P=0.02, respectively) in Group B versus Group A. The IL-6 and insulin concentrations and the HOMA-A index were positively correlated with the cortisol concentration and were negatively correlated with the NO concentration. With the exception of adiponectin, the other variables were associated with blindness. We concluded that blindness in PDH is a haemodynamic event associated with metabolic changes, with the increase in the IL-6 concentration and the decrease in the NO concentration affecting the retinal vasculature and producing a high risk of vision loss.

Low dose of insulin detemir controls glycaemia, insulinemia and prevents diabetes mellitus progression in the dog with pituitary-dependent hyperadrenocorticism.

Diabetes is often associated with pituitary-dependent hyperadrenocorticism (PDH). Hypercortisolism causes insulin resistance and affects ß-cell function. The purpose of this study was to test if daily administration of a long-acting insulin analogue during the first month of anti-PDH treatment can prevent progress to diabetes in these animals. Twenty-six PDH dogs were divided into three groups: one group with glycaemia <5.83 mmol/L and two groups with glycaemia >5.83 mmol/L and <9.35 mmol/L, one of which received insulin detemir during 4 months. Dogs with glycaemia <5.83 mmol/L and those with glycaemia >5.83 mmol/L which received insulin did not develop diabetes. In the non-insulin group, 6/7 dogs developed diabetes after the third month. There is a 13-fold higher risk of diabetes in dogs with glycaemia >5.83 mmol/L and no insulin treatment. Administering insulin detemir to dogs with PDH and glycaemia >5.83 mmol/L could prevent progression to diabetes.

Blindness in dogs with pituitary dependent hyperadrenocorticism: relationship with glucose, cortisol and triglyceride concentration and with ophthalmic blood flow.

Pituitary dependent hyperadrenocorticism (PDH) shows a high morbidity and blindness is one of its complications. Compression of the optic chiasm (OC) by the hypophysis adenoma is one of the causes. Another cause could be due to vascular and metabolic alterations of the PDH. Out of a total of 70 dogs with confirmed diagnosis of PDH, 12/70 showed blindness. In only 2/12 the OC was compromised. Electroretinography in dogs without the OC being compromised showed altered A and B wave patterns. Ophthalmological Doppler showed an alteration of the blood flow only in blind dogs without OC compression. Cortisol concentrations (Co), triglycerides (Tg) and glycaemia (G) were greater in 10 dogs with non-compressive blindness vs. dogs with conserved vision. Loss of vision correlated with the increase in these variables. Blindness in dogs with PDH would be related to changes in retinal blood flow, associated to higher Co, Tg and G concentrations.

A comparative study by age and gender of the pituitary adenoma and ACTH and alpha-MSH secretion in dogs with pituitary-dependent hyperadrenocorticism.

Pituitary-dependent hyperadrenocorticism (PDH) is frequent in dogs. Little is known about its presentation in different age groups and its characteristics. Dividing the population under study (n=107) into three age groups we observed that 11.2% were young, 51.4% adults and 37.4% aged. Using magnetic resonance, pituitary tumours were intra-sellar (IS) in 30.8% and extra-sellar (ES) in 62.6% and the pars intermedia (PI) was affected in 6.5%. ES are predominant in females and IS in males (p<0.0001). In the adult-aged population, the ES and PI are predominant, while in the young, the IS predominate (p<0.0001). ACTH concentration was greater in the ES vs. IS (p<0.05). alpha-MSH did not present significant differences according to tumour size, showing a negative correlation (r=-0.47; p<0.01) vs. ACTH. Differences in adenoma size according to gender and their age-related frequency of apparition could be because of different origins of the corticotrophinoma.

Corticotroph adenoma in the dog: pathogenesis and new therapeutic possibilities.

The corticotrophinoma, causing pituitary dependent hypercortisolism, represents the highest percentage of pituitary tumours in the dog. The mechanism by which it develops is currently unknown and two theories are postulated: the hypothalamic and the monoclonal. It is not clear either what factors are involved in the tumour genesis; nevertheless, firm candidates are the Rb1 gene, proteins p27, p21 and p16, as are also defects in the glucocorticoid receptor and Nur77/Nurr1. The role of BMPs remains to be evaluated in greater depth. Although at present the chosen treatment in human is surgical, there are various pharmacological treatments already in use that have favourable results and others, still under research, also showing promising results.

Diurnal ACTH and plasma cortisol variations in healthy dogs and in those with pituitary-dependent Cushing's syndrome before and after treatment with retinoic acid.

Daytime variations in ACTH and plasma cortisol were studied in healthy dogs and in dogs with pituitary-dependent hypercortisolism (PDH), before and after treatment with retinoic acid. In control dogs ACTH showed a higher concentration at 8.00 AM and between 2.00 and 6.00 PM, with the lowest concentration registered at 10.00 AM (p<0.05 vs. 8.00 AM and 2.00 PM and p<0.01 vs. 4.00 PM). Cortisol did not show significant differences. In dogs with PDH, ACTH was lower at 8.00 AM (ACTH: p<0.01 vs. 2.00 and 4.00 PM; and p<0.05 vs. 6.00 PM). The lowest cortisol concentration was registered at 8.00 AM and 8.00 PM and the highest at 4.00 PM (p<0.05 vs. 8.00 AM and p<0.01 vs. 8.00 PM). After treatment, the lowest ACTH concentration was registered at 10.00 AM (p<0.01 vs. 2.00 and 4.00 PM). To conclude, the adrenal is desensitized in PDH possibly showing negative in diagnostic tests.