Quality of life and response to treatment in cats with hypersomatotropism: the owners' point of view

OBJECTIVES

The aim of this study was to collect clinical information from owners of cats with hypersomatotropism (HS) distributed worldwide, assessing the impact of HS and its treatments on cats' quality of life (QoL) and survival time.

METHODS

A survey focused on clinical presentation, diagnostic procedures, treatments, cats' QoL and disease progression was distributed worldwide to owners of cats with HS. The owner's perception of the cats' QoL before and after or during treatment was defined using a score ranging from 1 (poor) to 5 (excellent). Improvement following treatment (IFT) was quantified using a score ranging from 1 (absent) to 5 (obvious). Different treatment groups, including at least five cases, were compared.

RESULTS

A total of 127 cats were included from at least 11 different countries. Among these, 120 (95%) were diabetic and 7 (5%) were not. Out of 120 diabetic cats, 55 (46%) were treated with insulin as a single treatment (INS). Other treatments were not mentioned to owners in 35/120 (29%) cases. The median QoL score at diagnosis was 2 (range 1-5) and improved after treatment in all groups. Cabergoline (4; range 1-5), radiotherapy (4; range 2-5) and hypophysectomy (5; range 4-5) showed better median IFT scores compared with INS (3; range 1-5) (P = 0.046, P <0.002 and P <0.0001, respectively). Hypophysectomy IFT proved superior to cabergoline (P = 0.047) and was equal to radiotherapy IFT (P = 0.32). No difference was found between cabergoline and radiotherapy IFT (P = 0.99). The median survival time (MST) was 24 months (range 0-75 months). Cats treated with INS showed shorter MST (22 months; range 0-69 months) compared with cats treated with causal treatments combined (36 months; range 3-75 months) (P = 0.04).

CONCLUSIONS AND RELEVANCE

Not all cats with HS will have diabetes mellitus. Causal treatments seem associated with the greatest improvements in perceived cats' QoL and survival; such treatments should therefore be discussed with owners. Cabergoline could be an effective alternative management option.

One hundred years of insulin: Is it time for smart?

Smarter understanding of diabetes pathophysiology and pharmacology of insulin therapy can lead to better clinical outcomes. Rather than looking for an insulin formulation that is considered "best" for a general population, it could be appropriate to seek the "smart" insulin choice, tailored to the specific clinical situation. Different treatment goals should be considered, with pros and cons to each. Ideally, insulin therapy in most diabetic dogs should mimic a "basal-bolus" pattern. The "intermediate"-acting insulin formulations might provide better "bolus" treatment in dogs than the rapid-acting formulations used in people. In patients with some residual beta cell function such as many diabetic cats, administering only a "basal" insulin might lead to complete normalisation of blood glucose concentrations. Insulin suspensions (neutral protamine Hagedorn, neutral protamine Hagedorn/regular mixes, lente and protamine zinc insulin) as well as insulin glargine U100 and detemir are "intermediate"-acting formulations that are administered twice daily. For a formulation to be an effective and safe "basal" insulin, its action should be roughly the same every hour of the day. Currently, only insulin glargine U300 and insulin degludec meet this standard in dogs, whereas in cats, insulin glargine U300 is the closest option.

Mapping the genetic basis of diabetes mellitus in the Australian Burmese cat (Felis catus)

Diabetes mellitus, a common endocrinopathy affecting domestic cats, shares many clinical and pathologic features with type 2 diabetes in humans. In Australia and Europe, diabetes mellitus is almost four times more common among Burmese cats than in other breeds. As a genetically isolated population, the diabetic Australian Burmese cat provides a spontaneous genetic model for studying diabetes mellitus in humans. Studying complex diseases in pedigreed breeds facilitates tighter control of confounding factors including population stratification, allelic frequencies and environmental heterogeneity. We used the feline SNV array and whole genome sequence data to undertake a genome wide-association study and runs of homozygosity analysis, of a case–control cohort of Australian and European Burmese cats. Our results identified diabetes-associated haplotypes across chromosomes A3, B1 and E1 and selective sweeps across the Burmese breed on chromosomes B1, B3, D1 and D4. The locus on chromosome B1, common to both analyses, revealed coding and splice region variants in candidate genes, ANK1, EPHX2 and LOX2, implicated in diabetes mellitus and lipid dysregulation. Mapping this condition in Burmese cats has revealed a polygenic spectrum, implicating loci linked to pancreatic beta cell dysfunction, lipid dysregulation and insulin resistance in the pathogenesis of diabetes mellitus in the Burmese cat.

Epidemiological study of dogs with diabetes mellitus attending primary care veterinary clinics in Australia

BACKGROUND

The objectives of this study were to establish the prevalence, risk factors and comorbidities/sequelae for diabetes mellitus (DM) in Australian dogs presented to first-opinion veterinary practices.

METHODS

Electronic patient records of dogs (n=134,329) attending 152 veterinary clinics during 2017 were sourced through VetCompass Australia. They included 418 dogs with DM; a prevalence of 0.36 per cent (95 per cent CI 0.33 per cent to 0.39 per cent) in Australian dogs attending these veterinary clinics. By comparing with the reference group of rarer breeds and unidentified crossbreeds, multivariable modelling was used to reveal breeds (and their crosses) with significantly higher odds of having DM.

RESULTS

The results revealed that breeds (and their crosses) with significantly higher odds of having DM were Australian terriers (ORs=7.93 (95 per cent CI 2.83 to 22.27)), Siberian huskies (OR=6.24 (95 per cent CI 2.51 to 15.54)), English springer spaniels (OR=5.37 (95 per cent CI 1.48 to 19.53)), West Highland white terriers (OR=4.85 (95 per cent CI 2.55 to 9.25)), miniature schnauzers (OR=3.47 (95 per cent CI 1.16 to 10.35)), all types of poodles (OR=3.41 (95 per cent CI 2.07 to 5.61)), bichon frises (OR=3.41 (95 per cent CI 1.65 to 7.01)), schnauzers (OR=3.18 (95 per cent CI 1.42 to 7.11)) and cavalier King Charles spaniels (CKCS; OR=1.84 (95 per cent CI 1.08 to 3.13)). Breeds with lower risk were German shepherd dogs (OR=0.11 (95 per cent CI 0.01 to 0.84)), golden retrievers (OR=0.09 (95 per cent CI 0.01 to 0.68)) and boxers (no cases identified). Fisher's exact tests showed that labradoodles were diagnosed significantly more often than purebred Labradors (P=0.04) and did not differ significantly from poodles (P=0.81). Cavoodles did not differ significantly from either CKCS (p~1.00) or poodles (P=0.12). Spoodles were significantly less diagnosed than poodles (P=0.003) but did not differ from cocker spaniels (P=0.66). Desexed male dogs had a higher odds of DM than entire male (OR=0.62 (95 per cent CI 0.39 to 0.98)) and desexed female dogs (OR=0.76 (95 per cent CI 0.61 to 0.96)). Comorbidities/sequelae associated with canine DM included suspected pancreatitis (OR 10.58 (95 per cent CI 5.17 to 22.78)), cataracts (OR 9.80 (95 per cent CI 5.65 to 17.35)), hyperadrenocorticism (OR 6.21 (95 per cent CI 3.29 to 11.88)), urinary tract infection (OR 5.09 (95 per cent CI 1.97 to 13.41)) and hypothyroidism (OR 4.10 (95 per cent CI 1.08 to 15.58)).

CONCLUSIONS

Breeds at most risk included Australian terriers and Siberian huskies as previously reported, as well as, for the first time, English springer spaniels. In contrast to other populations where there is female predisposition for DM, desexed male dogs in Australia were at increased risk for DM compared with both entire males and desexed females. This predisposition for desexed males to develop DM warrants further investigation.

Faecal microbiota of cats with insulin-treated diabetes mellitus

Microorganisms within the gastrointestinal tract significantly influence metabolic processes within their mammalian host, and recently several groups have sought to characterise the gastrointestinal microbiota of individuals affected by metabolic disease. Differences in the composition of the gastrointestinal microbiota have been reported in mouse models of type 2 diabetes mellitus, as well as in human patients. Diabetes mellitus in cats has many similarities to type 2 diabetes in humans. No studies of the gastrointestinal microbiota of diabetic cats have been previously published. The objectives of this study were to compare the composition of the faecal microbiota of diabetic and non-diabetic cats, and secondarily to determine if host signalment and dietary factors influence the composition of the faecal microbiota in cats. Faecal samples were collected from insulin-treated diabetic and non-diabetic cats, and Illumina sequencing of the 16S rRNA gene and quantitative PCR were performed on each sample. ANOSIM based on the unweighted UniFrac distance metric identified no difference in the composition of the faecal microbiota between diabetic and non-diabetic cats, and no significant differences in the proportions of dominant bacteria by phylum, class, order, family or genus as determined by 16S rRNA gene sequencing were identified between diabetic and non-diabetic cats. qPCR identified a decrease in Faecalibacterium spp. in cats aged over ten years. Cat breed or gender, dietary carbohydrate, protein or fat content, and dietary formulation (wet versus dry food) did not affect the composition of the faecal microbiota. In conclusion, the composition of the faecal microbiota was not altered by the presence of diabetes mellitus in cats. Additional studies that compare the functional products of the microbiota in diabetic and non-diabetic cats are warranted to further investigate the potential impact of the gastrointestinal microbiota on metabolic diseases such as diabetes mellitus in cats.

Acquired proximal renal tubulopathy in dogs exposed to a common dried chicken treat: retrospective study of 108 cases (2007-2009)

BACKGROUND

Proximal renal tubulopathy was reported in Australian dogs with markedly increased frequency from September 2007.

METHODS

Two veterinarian-completed surveys were launched in response to an increased incidence of acquired proximal renal tubulopathy in dogs. The selection criterion for inclusion was glucosuria with blood glucose < 10 mmol/L. Data collected included signalment, presenting signs, history of feeding treats, results of urinalysis and blood tests, treatment and time to resolution of clinical signs.

RESULTS

A total of 108 affected dogs were studied. All had been fed the same brand of dried chicken treats, made in China, for a median of 12 weeks (range, 0.3-78 weeks). Small breeds (< 10 kg) accounted for 88% of cases. Common presenting signs included polyuria/polydipsia (76%), lethargy (73%), inappetence (65%) and vomiting (54%). Common biochemical findings included euglycaemia (74%; 71/96), hypoglycaemia (23%; 22/96), acidosis (77%; 20/26), hypokalaemia (45%; 38/84), hypophosphataemia (37%; 28/75) and azotaemia (27%; 23/85). In addition to discontinuation of treats, 64 dogs received medical treatment, including intravenous fluids (52%) and oral electrolyte, amino acid or vitamin supplements. Six dogs died or were euthanased. Two dogs were necropsied. Histopathological findings consisted of proximal tubular necrosis accompanied by regeneration. Time to resolution of clinical signs in 35 survivors available for follow-up was < 2 weeks (n = 8), 2-4 weeks (n = 2), 5-7 weeks (n = 5) and 2-6 months (n = 10).

CONCLUSION

Of the 108 dogs with acquired proximal renal tubulopathy contemporaneous with chicken treat consumption, most survived but many required aggressive supportive care. The treats likely contained a toxin targeting the proximal renal tubules. Diet history and urinalysis were vital for diagnosis.

Association of postprandial serum triglyceride concentration and serum canine pancreatic lipase immunoreactivity in overweight and obese dogs

BACKGROUND

Hypertriglyceridemia has been proposed to contribute to the risk of developing pancreatitis in dogs.

OBJECTIVES

To determine associations between postprandial serum triglyceride concentrations and canine pancreatic lipase immunoreactivity (cPLI) concentrations or pancreatic disease.

ANIMALS

Thirty-five client-owned overweight (n = 25) or obese (n = 10) dogs weighing >10 kg.

METHODS

Healthy dogs were prospectively recruited for a cross-sectional study. Serum triglyceride concentrations were measured before and hourly for 12 hours after a meal. Fasting cPLI and canine trypsin-like immunoreactivity (cTLI) concentrations were assayed. Cut-off values for hypertriglyceridemia were set a priori for fasting (≥ 88, ≥ 177, ≥ 354, ≥ 885 mg/dL) and peak postprandial (≥ 133, ≥ 442, ≥ 885 mg/dL) triglyceride concentrations. The association between hypertriglyceridemia and high cPLI concentrations was assessed by exact logistic regression. Follow-up was performed 4 years later to determine the incidence of pancreatic disease.

RESULTS

Eight dogs had peak postprandial triglycerides >442 mg/dL and 3 dogs had fasting serum cPLI concentrations ≥ 400 μg/L. Odds of high cPLI concentrations were 16.7 times higher in dogs with peak postprandial triglyceride concentrations ≥ 442 mg/dL relative to other dogs (P < .001). Fasting triglyceride concentration was not significantly associated with cPLI concentrations. None of the dogs with high triglyceride concentrations and one of the dogs with low fasting and peak postprandial triglyceride concentrations developed clinically important pancreatic disease.

CONCLUSIONS AND CLINICAL IMPORTANCE

Overweight and obese dogs with peak serum postprandial triglyceride concentrations ≥ 442 mg/dL after a standard meal are more likely to have serum cPLI concentrations ≥ 400 μg/L, but did not develop clinically important pancreatic disease.

Spontaneously obese dogs exhibit greater postprandial glucose, triglyceride, and insulin concentrations than lean dogs

Dogs do not appear to progress from obesity-induced insulin resistance to type 2 diabetes mellitus. Both postprandial hyperglycemia and postprandial hypertriglyceridemia have been proposed to cause or maintain beta cell failure and progression to type 2 diabetes mellitus in other species. Postprandial glucose, triglyceride, and insulin concentrations have not been compared in lean and obese dogs. We measured serum glucose, triglyceride, and insulin concentrations in nine naturally occurring obese and nine age- and gender-matched lean dogs. After a 24-h fast, dogs were fed half their calculated daily energy requirement of a standardized diet that provided 37% and 40% of metabolizable energy as carbohydrate and fat, respectively. Fasting and postprandial glucose and triglyceride concentrations were greater in the obese dogs (P < 0.001), although the mean insulin concentration for this group was five times greater than that of the lean group (P < 0.001). Most of the 0.6 mM (11 mg/dL) difference in mean postprandial glucose concentrations between lean and obese dogs was attributable to a subset of persistently hyperglycemic obese dogs with mean postprandial glucose concentrations 1.0 mM (18 mg/dL) greater than that in lean dogs. Persistently hyperglycemic obese dogs had lower triglyceride (P = 0.02 to 0.04) and insulin (P < 0.02) concentrations than other obese dogs. None of the dogs developed clinical signs of diabetes mellitus during follow-up for a median of 2.6 yr. We conclude that pancreatic beta cells in dogs are either not sensitive to toxicity because of mild hyperglycemia or lack another component of the pathophysiology of beta cell failure in type 2 diabetes mellitus.

A diet lower in digestible carbohydrate results in lower postprandial glucose concentrations compared with a traditional canine diabetes diet and an adult maintenance diet in healthy dogs

The aim of this study was to compare the effects of three diets with varying macronutrient and fibre contents on postprandial plasma glucose, triglyceride, free fatty acid, and insulin concentrations over a 12 h period in 12 healthy neutered lean dogs. Each diet was fed to each dog for 3 weeks in a three-period cross-over study. Plasma analyte concentrations were measured prior to and after a meal at the end of the third week of each period. Postprandial glucose concentrations for the moderate carbohydrate and fibre diet were 0.4-0.7 mmol/L (8-12 mg/dL) lower than for both higher carbohydrate diets (p≤0.02). Postprandial glucose, insulin, and triglyceride concentrations in some dogs did not return to baseline by 12 h after feeding of each of the three diets. These results indicate that the moderate carbohydrate and fibre diet warrants evaluation in diabetic dogs. Variables should be measured over at least 12 h after feeding to fully evaluate postprandial dietary effects on these analytes.

Distinct adiponectin profiles might contribute to differences in susceptibility to type 2 diabetes in dogs and humans

Dogs develop obesity-associated insulin resistance but not type 2 diabetes mellitus. Low adiponectin is associated with progression to type 2 diabetes in obese humans. The aims of this study were to compare total and high molecular weight (HMW) adiponectin and the ratio of HMW to total adiponectin (S(A)) between dogs and humans and to examine whether total or HMW adiponectin or both are associated with insulin resistance in naturally occurring obese dogs. We compared adiponectin profiles between 10 lean dogs and 10 lean humans and between 6 lean dogs and 6 age- and sex-matched, client-owned obese dogs. Total adiponectin was measured with assays validated in each species. We measured S(A) with velocity centrifugation on sucrose gradients. The effect of total and HMW adiponectin concentrations on MINMOD-estimated insulin sensitivity was assessed with linear regression. Lean dogs had total and HMW adiponectin concentrations three to four times higher than lean humans (total: dogs 32 ± 5.6 mg/L, humans 10 ± 1.3 mg/L, P<0.001; HMW: dogs 25 ± 4.5 mg/L, humans 6 ± 1.3 mg/L, P<0.001) and a higher S(A) (dogs: 0.78 ± 0.05; humans: 0.54 ± 0.08, P = 0.002). Adiponectin concentrations and S(A) were not lower in obese dogs (0.76 ± 0.05 in both groups; P=1). Total adiponectin, HMW adiponectin, and S(A) were not associated with insulin sensitivity in dogs. We propose that differences in adiponectin profiles between humans and dogs might contribute to the propensity of humans but not dogs to develop type 2 diabetes. Dogs with chronic, naturally occurring obesity do not have selectively reduced HMW adiponectin, and adiponectin does not appear to be important in the development of canine obesity-associated insulin resistance.

Adiponectin profiles are affected by chronic and acute changes in carbohydrate intake in healthy cats

Adiponectin is a key adipokine that regulates carbohydrate and lipid metabolism. It circulates in stable low (LMW) and high molecular weight (HMW) forms. The aims of this study were to characterize baseline adiponectin profiles (total, LMW and HMW multimers) in healthy cats and to assess the effects of varying dietary carbohydrate content on adiponectin profiles. Cats were maintained on a diet with moderate carbohydrate content (37% metabolisable energy [ME]) for 4 weeks and then randomly allocated to either a low carbohydrate (19% ME) or high carbohydrate (52% ME) diet for 4 weeks. Fasting and postprandial plasma adiponectin profiles were measured by ELISA and sucrose gradient/Western blot. After consuming the moderate carbohydrate diet for 4 weeks, fasting total, HMW and LMW plasma adiponectin concentrations were 5.0±0.6, 2.5±0.5 and 2.6±0.2 μg/mL, respectively. After changing to the low carbohydrate diet, fasting total adiponectin was unchanged but HMW adiponectin increased and LMW adiponectin decreased. No significant postprandial changes were observed. Cats consuming the high carbohydrate diet had increased fasting total and LMW adiponectin with no change in HMW adiponectin. In the postprandial state total adiponectin was reduced and there was a trend towards a decrease in HMW (p=0.086) but not LMW multimers. These data indicate that feline adiponectin multimer profiles are similar to those reported in other species and demonstrate that changes in plasma adiponectin occur in response to chronic and acute carbohydrate intake and these reflect differential changes in adiponectin multimers.

Compensation for obesity-induced insulin resistance in dogs: assessment of the effects of leptin, adiponectin, and glucagon-like peptide-1 using path analysis

The hormonal mediators of obesity-induced insulin resistance and compensatory hyperinsulinemia in dogs have not been identified. Plasma samples were obtained after a 24-h fast from 104 client-owned lean, overweight, and obese dogs. Plasma glucose and insulin concentrations were used to calculate insulin sensitivity and β-cell function with the use of the homeostasis model assessment (HOMA(insulin sensitivity) and HOMA(β-cell function), respectively). Path analysis with multivariable linear regression was used to identify whether fasting plasma leptin, adiponectin, or glucagon-like peptide-1 concentrations were associated with adiposity, insulin sensitivity, and basal insulin secretion. None of the dogs were hyperglycemic. In the final path model, adiposity was positively associated with leptin (P < 0.01) and glucagon-like peptide-1 (P = 0.04) concentrations. No significant total effect of adiposity on adiponectin in dogs (P = 0.24) was observed. If there is a direct effect of leptin on adiponectin, then our results indicate that this is a positive relationship, which at least partly counters a negative direct relationship between adiposity and adiponectin. Fasting plasma leptin concentration was directly negatively associated with fasting insulin sensitivity (P = 0.01) and positively associated with β-cell function (P < 0.01), but no direct association was observed between adiponectin concentration and either insulin sensitivity or β-cell function (P = 0.42 and 0.11, respectively). We conclude that dogs compensate effectively for obesity-induced insulin resistance. Fasting plasma leptin concentrations appear to be associated with obesity-associated changes in insulin sensitivity and compensatory hyperinsulinemia in naturally occurring obese dogs. Adiponectin does not appear to be involved in the pathophysiology of obesity-associated changes in insulin sensitivity.

Adiposity and adiponectin in dogs: investigation of causes of discrepant results between two studies

Although one study showed lower adiponectin concentrations in obese dogs, other recent studies indicate that adiponectin might not be decreased in obese dogs, raising the possibility that the physiology of adiponectin is different in dogs than in humans. The aim of this study was to investigate possible causes of the discrepancy between the two largest studies to date that assessed the association between adiposity and adiponectin concentration in dogs, including the validity of the assay, laboratory error, and the effects of breed, sex, and neuter status on the relationship between adiposity and adiponectin concentrations. Adiponectin concentrations measured with a previously validated adiponectin ELISA were compared with those estimated by Western blotting analysis of reduced and denatured plasma samples. The possibility of laboratory error and the effect of EDTA anticoagulant and aprotinin were tested. Adiponectin concentration was measured by ELISA in 20 lean dogs (10 male and 10 female, 5 neutered in each sex). There was close correlation between adiponectin concentrations measured by ELISA and those estimated by Western blotting analysis (r = 0.90; P < 0.001). There was no substantial effect of EDTA, aprotinin, or laboratory error on the results. There was confounding by neuter status of the relationship between adiposity and adiponectin concentrations, but adiponectin concentrations were not significantly lower in male than in female lean dogs (females, 36 mg/L; males, 26 mg/L; P > 0.20) and were not significantly lower in intact than in neutered lean male dogs (intact, 28 mg/L; neutered, 23 mg/L; P = 0.49). We conclude that the adiponectin ELISA previously validated for use in dogs appears to be suitable for determination of canine adiponectin concentrations and that testosterone does not appear to have a strong effect on plasma adiponectin concentrations in dogs. Obesity might decrease adiponectin concentrations in intact but not in neutered dogs.

Evaluation of beta-cell sensitivity to glucose and first-phase insulin secretion in obese dogs

OBJECTIVE

To compare beta-cell sensitivity to glucose, first-phase insulin secretion, and glucose tolerance between dogs with naturally occurring obesity of > 2 years' duration and lean dogs.

ANIMALS

17 client-owned obese or lean dogs.

PROCEDURES

Frequently sampled IV glucose tolerance tests were performed with minimal model analysis on 6 obese dogs and matched controls. Glucagon stimulation tests were performed on 5 obese dogs and matched controls.

RESULTS

Obese dogs were half as sensitive to the effects of insulin as lean dogs. Plasma glucose concentrations after food withholding did not differ significantly between groups; plasma insulin concentrations were 3 to 4 times as great in obese as in lean dogs. Obese dogs had plasma insulin concentrations twice those of lean dogs after administration of glucose and 4 times as great after administration of glucagon. First-phase insulin secretion was greater in obese dogs.

CONCLUSIONS AND CLINICAL RELEVANCE

Obese dogs compensated for obesity-induced insulin resistance by secreting more insulin. First-phase insulin secretion and beta-cell glucose sensitivity were not lost despite years of obesity-induced insulin resistance and compensatory hyperinsulinemia. These findings help explain why dogs, unlike cats and humans, have not been documented to develop type 2 diabetes mellitus.

Use of a meal challenge test to estimate peak postprandial triglyceride concentrations in dogs

OBJECTIVE

To develop a standardized meal challenge test by assessing associations between food-withheld preprandial (ie, fasting) and postprandial triglyceride concentrations, determining the most appropriate sampling time to detect the peak concentration (highest postprandial concentration), and estimating reference intervals for fasting and postprandial concentrations in healthy dogs.

ANIMALS

12 lean healthy mixed-breed dogs.

PROCEDURES

Dogs were fed a dry commercially available diet (fat, 31% metabolizable energy) for 3 weeks. After food was withheld for 23 to 24 hours, plasma triglyceride concentrations were measured 1 and 0.083 hours before and 1, 2, 3, 4, 5, 6, 9, and 12 hours after feeding of a standardized challenge meal (median amount eaten, 63 kcal/kg [127 kcal/kg⁰.⁷⁵]). Correlation and agreement between concentrations at peak and other time points were assessed by use of correlation coefficients and Bland-Altman limits of agreement. Reference intervals were calculated by use of a robust method.

RESULTS

Fasting and peak triglyceride concentrations were not closely associated. The highest concentration among samples obtained 2, 5, and 6 hours after meal consumption had closest agreement with peak concentration. In 5 of 12 dogs, concentrations 12 hours after eating were still significantly above baseline concentration (mean of each dog's fasting concentrations).

CONCLUSIONS AND CLINICAL RELEVANCE

Fasting triglyceride concentration could not be used to accurately predict peak concentration. When estimating peak concentration, multiple samples should be collected 2, 5, and 6 hours after consumption of a standardized meal. Food may need to be withheld for > 12 hours when assessing fasting concentrations in healthy dogs.

Basal measures of insulin sensitivity and insulin secretion and simplified glucose tolerance tests in dogs

There is need for simple, inexpensive measures of glucose tolerance, insulin sensitivity, and insulin secretion in dogs. The aim of this study was to estimate the closeness of correlation between fasting and dynamic measures of insulin sensitivity and insulin secretion, the precision of fasting measures, and the agreement between results of standard and simplified glucose tolerance tests in dogs. A retrospective descriptive study using 6 naturally occurring obese and 6 lean dogs was conducted. Data from frequently sampled intravenous glucose tolerance tests (FSIGTTs) in 6 obese and 6 lean client-owned dogs were used to calculate HOMA, QUICKI, fasting glucose and insulin concentrations. Fasting measures of insulin sensitivity and secretion were compared with MINMOD analysis of FSIGTTs using Pearson correlation coefficients, and they were evaluated for precision by the discriminant ratio. Simplified sampling protocols were compared with standard FSIGTTs using Lin's concordance correlation coefficients, limits of agreement, and Pearson correlation coefficients. All fasting measures except fasting plasma glucose concentration were moderately correlated with MINMOD-estimated insulin sensitivity (|r| = 0.62-0.80; P < 0.03), and those that combined fasting insulin and glucose were moderately closely correlated with MINMOD-estimated insulin secretion (r = 0.60-0.79; P < 0.04). HOMA calculated using the nonlinear formulae had the closest estimated correlation (r = 0.77 and 0.74) and the best discrimination for insulin sensitivity and insulin secretion (discriminant ratio 4.4 and 3.4, respectively). Simplified sampling protocols with half as many samples collected over 3 h had close agreement with the full sampling protocol. Fasting measures and simplified intravenous glucose tolerance tests reflect insulin sensitivity and insulin secretion derived from frequently sampled glucose tolerance tests with MINMOD analysis in dogs.

Using 20-gauge percutaneous peripheral catheters to reliably collect serial 4-mL blood samples from conscious dogs

OBJECTIVE

To determine the reliability of collecting serial 4-mL blood samples over 13 h using a 20-gauge, cephalic catheter in conscious dogs.

DESIGN

Prospective, observational study.

ANIMALS

Twelve (6 males, 6 females) healthy, neutered, lean dogs.

PROCEDURE

Percutaneous placement of a 20-gauge, 1.1 x 30 mm intravenous over-the-needle catheter into the cephalic vein was performed in each dog on three occasions. Catheter patency was maintained by intermittent flushing with 0.9% saline and 1 IU/mL heparinised saline solutions. Blood samples (4 mL) were obtained at 10 time-points over 13 h, with close monitoring of the dogs and the indwelling catheters. Blood volume, resistance on aspirating blood sample (minimal or marked resistance) and the methods used to improve blood flow were recorded.

RESULTS

A high proportion (93%) of blood sample collections achieved the required 4-mL volume, and the remaining samples were greater than 1.5 mL. Of the 358 collections via the cephalic catheter, 311 (87%) were obtained with 'minimal resistance'. The remaining collections had 'marked resistance' (n=47) and were associated with a loose catheter in 11% (5/47) and of unknown cause in 89% (42/47). After 'marked resistance' had been encountered and the catheter was flushed with saline and heparin solutions, subsequent sampling with 'minimal resistance' was frequently possible from the same catheter.

CONCLUSION

Use of a percutaneous, 20-gauge intravenous cephalic catheter allowed reliable serial collection of 4-mL blood samples over 13 h in conscious dogs.

Disease prevalence among dogs and cats in the United States and Australia and proportions of dogs and cats that receive therapeutic diets or dietary supplements

OBJECTIVE

To estimate disease prevalence among dogs and cats in the United States and Australia and proportions of dogs and cats that receive therapeutic diets or dietary supplements.

DESIGN

Telephone survey. Sample Population-Dog and cat owners located in 5 geographic areas.

PROCEDURES

A telephone survey was administered to dog and cat owners.

RESULTS

Of 18,194 telephone calls that were made, 1,104 (6%) were to individuals who owned at least 1 dog or cat and agreed to participate. Information was collected for 635 dogs and 469 cats. Only 14 (1%) respondents indicated that their pet was unhealthy, but 176 (16%) indicated that their pets had 1 or more diseases. The most common diseases were musculo-skeletal, dental, and gastrointestinal tract or hepatic disease. Many owners (n = 356) reported their pets were overweight or obese, but only 3 reported obesity as a health problem in their pets. Owners of 28 (2.5%) animals reported that they were feeding a therapeutic diet, with the most common being diets for animals with renal disease (n = 5), reduced-calorie diets (5), and reduced-fat diets (4). Owners of 107 of 1,076 (9.9%) animals reported administering dietary supplements to their pets. Multivitamins (n = 53 animals), chondroprotective agents (22), and fatty acids (13) were the most common dietary supplements used.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that most dogs and cats reported by their owners to have a health problem were not being fed a therapeutic diet. In addition, the rate of dietary supplement use was lower than that reported for people.

Canine diabetes mellitus: can old dogs teach us new tricks?

BACKGROUND

Diabetes is common in dogs, with an estimated prevalence of 0.32% in the UK. Clinical signs, as in man, include polydipsia, polyuria and weight loss, associated with hyperglycaemia and glucosuria. Diabetes typically occurs in dogs between 5 and 12 years of age, and is uncommon under 3 years of age. Breeds predisposed to diabetes include the Samoyed, Tibetan Terrier and Cairn Terrier, while others such as the Boxer and German Shepherd Dog seem less susceptible. These breed differences suggest a genetic component, and at least one dog leucocyte antigen haplotype (DLA DRB1*009, DQA1*001, DQB1*008) appears to be associated with susceptibility to diabetes.

METHODS

Canine diabetes can be classified into insulin deficiency diabetes (IDD), resulting from a congenital deficiency or acquired loss of pancreatic beta cells, or insulin resistance diabetes resulting mainly from hormonal antagonism of insulin function.

RESULTS

There is no evidence for a canine equivalent of human type 2 diabetes. Adult-onset IDD, requiring insulin therapy, is the most common form, with pancreatitis and/or immune-mediated beta cell destruction considered to be the major underlying causes of the disease.

DISCUSSION

Autoantibodies to insulin, recombinant canine GAD65 and/or canine islet antigen-2 have been identified in a proportion of newly diagnosed diabetic dogs, suggesting that autoimmunity is involved in the pathogenesis of disease in some patients.

CONCLUSION

The late onset and slow progression of beta cell dysfunction in canine diabetes resembles latent autoimmune diabetes of the adult in man.

Canine and Feline Diabetes Mellitus: Nature or Nurture?

There is evidence for the role of genetic and environmental factors in feline and canine diabetes. Type 2 diabetes is the most common form of diabetes in cats. Evidence for genetic factors in feline diabetes includes the overrepresentation of Burmese cats with diabetes. Environmental risk factors in domestic or Burmese cats include advancing age, obesity, male gender, neutering, drug treatment, physical inactivity, and indoor confinement. High-carbohydrate diets increase blood glucose and insulin levels and may predispose cats to obesity and diabetes. Low-carbohydrate, high-protein diets may help prevent diabetes in cats at risk such as obese cats or lean cats with underlying low insulin sensitivity. Evidence exists for a genetic basis and altered immune response in the pathogenesis of canine diabetes. Seasonal effects on the incidence of diagnosis indicate that there are environmental influences on disease progression. At least 50% of diabetic dogs have type 1 diabetes based on present evidence of immune destruction of beta-cells. Epidemiological factors closely match those of the latent autoimmune diabetes of adults form of human type 1 diabetes. Extensive pancreatic damage, likely from chronic pancreatitis, causes approximately 28% of canine diabetes cases. Environmental factors such as feeding of high-fat diets are potentially associated with pancreatitis and likely play a role in the development of pancreatitis in diabetic dogs. There are no published data showing that overt type 2 diabetes occurs in dogs or that obesity is a risk factor for canine diabetes. Diabetes diagnosed in a bitch during either pregnancy or diestrus is comparable to human gestational diabetes.

Evaluation of day-to-day variability of serial blood glucose concentration curves in diabetic dogs

OBJECTIVE

To evaluate day-to-day variability of serial blood glucose concentration curves in dogs with diabetes mellitus.

DESIGN

Prospective clinical study.

ANIMALS

10 dogs with diabetes mellitus.

PROCEDURE

Paired 12-hour serial blood glucose concentration curves performed during 2 consecutive days were obtained on 3 occasions from each dog. Dogs received the same dose of insulin and meal every 12 hours on both days. For each pair of curves, comparison was made between the results of days 1 and 2.

RESULTS

Mean absolute difference (without regard to sign) between days 1 and 2 for each parameter was significantly > 0, disproving the hypothesis that there is minimal day-to-day variability of serial blood glucose concentration curves when insulin dose and meals are kept constant. Coefficient of variation of the absolute difference between days 1 and 2 for each parameter ranged from 68 to 103%. Evaluation of the paired curves led to an opposite recommendation for adjustment of the insulin dose on day 2, compared with day 1, on 27% of occasions. Disparity between dosage recommendations was more pronounced when glucose concentration nadir was < 180 mg/dL (10 mmol/L) on 1 or both days. In this subset of 20 paired curves, an opposite recommendation for dosage adjustment was made on 40% of occasions.

CONCLUSIONS AND CLINICAL RELEVANCE

There is large day-to-day variation in parameters of serial blood glucose concentration curves in diabetic dogs. Day-to-day variability of serial blood glucose concentration curves has important clinical implications, particularly in dogs with good glycemic control.

Management of canine diabetes

The majority of diabetic dogs appear to have a form of type 1 diabetes analogous to the latent autoimmune diabetes of adults (LADA) in humans. Evidence of acute or chronic pancreatitis occurs in about 40% of diabetic dogs. Blindness caused by cataract formation eventually occurs in the majority of diabetic dogs and is not dependent on glycemic control. Insulin is the mainstay of therapy for diabetic dogs, and a conservative approach to insulin therapy is crucial. Most diabetic dogs require twice-daily dosing with lente or NPH insulin to adequately control their clinical signs. The diet fed should primarily be palatable and nutritionally balanced. Improved glycemic control may be achieved in some dogs if the diet contains increased insoluble fiber.

Effects of an oral vasopressin receptor antagonist (OPC-31260) in a dog with syndrome of inappropriate secretion of antidiuretic hormone

OBJECTIVE

The syndrome of inappropriate secretion of antidiuretic hormone is a rare disorder in dogs characterised by hypo-osmolality and persistent arginine vasopressin production in the absence of hypovolaemia and/or hypotension. The study describes the efficacy and safety of the nonpeptide selective arginine vasopressin V2 receptor antagonist OPC-31260 in a dog with the naturally occurring syndrome.

DESIGN

The detailed case history of a dog with spontaneous syndrome of inappropriate secretion of antidiuretic hormone that received long-term therapy with oral OPC-31260 is presented. Effects of the first dose of OPC-31260 and of a dose administered after a continuous dosing period of 12 days are reported.

PROCEDURE

Packed cell volume, plasma sodium, total protein, arginine vasopressin, renin activity, atrial natriuretic peptide, urine specific gravity, urine output, heart rate and body weight were monitored for 2 h before, and for 4 h after, the first dose of OPC-31260. The same parameters plus plasma osmolality and urine osmolality were monitored when an identical dose was administered after 12 days of therapy.

RESULTS

Oral administration of OPC-31260 at 3 mg/kg body weight resulted in marked aquaresis with increased urine output and decline in urine specific gravity within 1 h. Corresponding increases in concentrations of plasma sodium, plasma osmolality and plasma renin activity were recorded over a 4 h period. Arginine vasopressin concentration remained inappropriately elevated throughout the study. Results were similar when the trial procedure was repeated after a stabilisation period of 12 days. Long-term therapy with OPC-31260 at a dose of 3 mg/kg body weight orally every 12 h resulted in good control of clinical signs with no deleterious effects detected during a 3-year follow-up period. Despite sustained clinical benefits observed in this case, plasma sodium did not normalise with continued administration of the drug.

CONCLUSIONS

Treatment of a dog with naturally occurring syndrome of inappropriate secretion of antidiuretic hormone with OPC-31260 at 3 mg/kg body weight orally every 12 h resulted in marked aquaresis and significant palliation of clinical signs with no discernible side-effects detected over a 3-year period. Thus, OPC-31260 appears to offer a feasible medical alternative to water restriction for treatment of dogs with syndrome of inappropriate secretion of antidiuretic hormone. Higher doses of OPC-31260 may be required to achieve and maintain normal plasma sodium in dogs with this syndrome.