Salivary cortisol in healthy dogs: a randomized cross-over study to evaluate different saliva stimulation methods and their effects on saliva volume and cortisol concentration

BACKGROUND

Salivary cortisol collected at home is a useful test to diagnose and monitor Cushing's syndrome in humans. The main problem in dogs is to retrieve a sufficient amount of saliva. The aim of this study was to evaluate different salivary collection methods and compare their effects on volume, pH and cortisol concentration of saliva. Sixteen healthy Beagles were used in a 4 × 4 randomized crossover study with a washout period of 1 week between each of the following collection methods: 1. Salimetrics® cotton swab dipped in ginger powder (ginger group); 2. beef-flavored Salimetrics® (bouillon group); 3. Salivette® cotton swab with an enclosed treat (treat group); 4. plain Salimetrics® (control group). First, baseline saliva (plain cotton swab, S0) and, 2 min later, experimental saliva (according to group allocation above, SExp) were collected. Saliva was gathered by holding the swabs in the animal's mouth for 2 min. After the cross-over study, another saliva sample was collected from all dogs by the ginger method, using a 30 s sampling time (30s-ginger method). Cortisol concentrations were measured by liquid chromatography tandem mass spectrometry.

RESULTS

All three stimulation methods increased saliva production significantly (S0 compared to SExp: ginger p = 0.0005; bouillon p = 0.009; treat p = 0.007). Only ginger stimulation, however, generated a significantly higher amount of saliva (SExp) compared to the control group (p = 0.00001; median (range) amount of saliva for SExp: ginger 1200 ul (600-1700), bouillon 650 ul (200-1900), treat 700 ul (300-1000), control 400 ul (0-1100)). The amount of saliva retrieved by the 30s-ginger method was still higher than that from the control group (p = 0.0004). Bouillon and treat stimulation led to decreased pH values (bouillon, p = 0.0028; treat, 0.0018). Excitement was higher in the ginger group (p = 0.01). Chewing was intensified in the ginger and treat group (ginger, p = 0.003; treat, 0.0009). The cortisol concentration SExp was higher compared to that of S0 in the ginger and treat group (p = 0.02, 0.003). The experimental cortisol concentrations (SExp) were not different between groups.

CONCLUSIONS

The 30s-ginger method could prove useful in evaluating or monitoring dogs with Cushing's syndrome, as sampling at home for 30 s by the owner seems feasible.

Urinary tract infections in dogs with spontaneous hypercortisolism - frequency, symptoms and involved pathogens

INTRODUCTION

Dogs with hypercortisolism are predisposed to developing bacteriuria associated either with clinical signs of cystitis or without clinical signs (subclinical bacteriuria). Based on current guidelines, dogs with subclinical bacteriuria should not be treated with antibiotics because there is no evidence that treatment improves outcome and because unnecessary treatments should be avoided. Before these guidelines were published in 2019, dogs with hypercortisolism and bacteriuria were commonly treated with antibiotics irrespective of clinical signs. Comprehensive data on the frequency of bacterial cystitis, subclinical bacteriuria and the outcome of antimicrobial treatment in dogs with hypercortisolism is sparse. The aims of this study were to investigate dogs with hypercortisolism for the presence of bacterial cystitis and subclinical bacteriuria, to address the pathogens involved, and to assess the outcome of antibiotic treatment. Dogs newly diagnosed with hypercortisolism between 2005 and 2015 from which a urine bacterial culture was available were included. Statistical analysis was performed with non-parametric tests. Of the 161 client-owned dogs included, 29 (18%) showed bacteriuria, which was subclinical in 24 (83%) cases. Escherichia coli was the most commonly isolated pathogen (58%). Bacteriuria was not associated with sex or neutering status. In 14 dogs, follow-up data was available, of which 13 (93%) were treated with antimicrobials for 14 to 28 days. Follow-up bacterial culture (1 to 118 days after cessation of therapy) was negative in 10 (77%) treated dogs; a negative follow-up culture was not associated with gender, age or duration of treatment. Bacteriuria persisted in three treated dogs and the one untreated dog. The prevalence of positive bacterial urinary culture in dogs with hypercortisolism was lower than previously reported. In the majority of dogs, bacteriuria was subclinical. Most dogs had a negative bacterial culture result after antimicrobial treatment; however, more resistant bacteria were detected in persistently positive urine.

[Acromegaly due to a pituitary tumor in a dog - diagnosis, therapy and long-term follow-up]

INTRODUCTION

Acromegaly due to a pituitary tumor has so far only been described in 3 dogs. The present case report describes a 7-year-old male-castrated Labrador Retriever which was referred because of difficult-to-control diabetes. Physical examination revealed markedly enlarged head, tongue and paws, widened interdental spaces and thickening of the skin in the head and neck area. IGF-1 and GH were increased and the latter continued to be abnormal after somatostatin application. Computed tomography demonstrated a space-occupying lesion in the pituitary gland and the diagnosis of acromegaly due to a GH-producing tumor of the pituitary was made. The dog underwent radiation therapy with a 6MV linear accelerator (3×8Gy) and improved substantially. Two and a half years after radiation therapy the dog developed lethargy and anorexia and was euthanized. Necropsy was not permitted. This case report represents the description of a dog suffering from pituitary-dependent acromegaly which was successfully treated and had a long-term survival.

Comparison of two prepill cortisol concentrations in dogs with hypercortisolism treated with trilostane

Background

The ideal method for monitoring trilostane therapy in dogs with hypercortisolism is still open to debate. Recently, determination of the pre-trilostane (prepill) cortisol concentration has been proposed to be more repeatable than either post-trilostane or post-ACTH cortisol. The aim of this study was to compare two prepill cortisol concentrations in dogs with hypercortisolism during trilostane therapy. Sixteen client-owned dogs with naturally occurring hypercortisolism were prospectively included and cortisol concentrations were measured twice, 1 h apart, before the morning trilostane dose (prepill 1 and 2 cortisol).

Results

A total of 47 prepill cortisol measurement pairs were included. Compared to prepill 1, prepill 2 cortisol was higher in 15, equal in 8 and lower in 24 pairs. Group agreement between prepill 1 and 2 cortisol was 70% (moderate agreement - weighted kappa 0.55). In 30% of the pairs, group assignment was discrepant, implying a different therapeutic decision. In some dogs certain circumstances (e.g. excessive barking, difficulties during blood collection, excitement at arrival) were identified as potential factors explaining the discrepancy between prepill 1 and 2 cortisol measurements.

Conclusions

In a substantial number of dogs treated with trilostane, the two prepill cortisol concentrations differed. Part of this difference might be ascribable to stressful events during test performance. When using prepill cortisol measurements to monitor trilostane therapy, recording of any incident during handling that might affect cortisol release might be helpful to make a reliable decision about a trilostane dose adaptation.

Effects of Trilostane on urinary Catecholamines and their metabolites in dogs with Hypercortisolism

BACKGROUND

Glucocorticoids influence the synthesis and metabolism of catecholamines (epinephrine and norepinephrine) and metanephrines (metanephrine and normetanephrine). The aim of this study was to measure urinary catecholamines and metanephrines in dogs with hypercortisolism before and during trilostane therapy. Urine samples were collected during initial work up and during therapy with trilostane in 14 dogs with hypercortisolism and in 25 healthy dogs. Epinephrine, norepinephrine, metanephrine and normetanephrine were measured using high-pressure liquid chromatography and expressed as ratios to urinary creatinine concentration.

RESULTS

Untreated dogs with hypercortisolism had significantly higher epinephrine, norepinephrine, and normetanephrine:creatinine ratios compared to healthy dogs. During trilostane therapy, urinary catecholamines and their metabolites did not decrease significantly. However, dogs with low post-ACTH cortisol concentrations during trilostane therapy had less increased epinephrine, norepinephrine and normetanephrine:creatinine ratios compared to healthy dogs. There was no correlation of urinary catecholamines and their metabolites with baseline or post-ACTH cortisol or endogenous ACTH concentrations during trilostane therapy.

CONCLUSION

Influences between steroid hormones and catecholamines seem to occur, as dogs with hypercortisolism have significantly higher urinary epinephrine, norepinephrine, and normetanephrine:creatinine ratios. Once-daily trilostane therapy does not lead to a significant decrease in catecholamines and their metabolites. Trilostane-treated dogs still have increased urinary epinephrine, norepinephrine and normetanephrine:creatinine ratios during trilostane therapy.

Haemotropic mycoplasmas of cats and dogs: transmission, diagnosis, prevalence and importance in Europe

Haemotropic mycoplasmas (or haemoplasmas) are the causative agents of infectious anaemia in many mammalian species. They were previously known as Haemobartonella and Eperythrozoon species. The development of sensitive, specific PCR assays has expanded our knowledge of these agents and PCR is the method of choice to diagnose and differentiate haemoplasma infections. In felids, Mycoplasma haemofelis, 'Candidatus Mycoplasma haemominutum' and 'Candidatus Mycoplasma turicensis' have been described. They vary strongly in their pathogenic potential and co-factors may influence the disease severity. In dogs, Mycoplasma haemocanis and 'Candidatus Mycoplasma haematoparvum' are known; clinical signs are mainly found in immunocompromised dogs. Transmission of haemoplasmas may occur via infected blood (aggressive interaction, transfusion) or blood-sucking arthropods. Infections can be treated with Doxycycline, although it is disputable whether the infection is completely eliminated. Feline haemoplasmas must be expected in cats all over Europe, while canine haemoplasmas are mainly encountered in dogs in Mediterranean countries but should also be considered in Swiss dogs with a travel history.

Feline leukaemia provirus load during the course of experimental infection and in naturally infected cats

Feline leukaemia virus (FeLV) infection in domestic cats can vary in its outcome (persistent, transient, no infection) for reasons that are not entirely known. It was hypothesized that the initial virus and provirus load could significantly influence the course of retrovirus infection. To determine the role of provirus loads, two methods of PCR, a nested PCR and a fluorogenic probe-based (TaqMan) real-time quantitative PCR, which were specific to the U3 region of FeLV-A were established. FeLV provirus in naturally and experimentally infected cats was then measured. Only 3 weeks after experimental FeLV-A infection, persistently infected cats demonstrated higher provirus loads and lower humoral immune responses than cats that had overcome antigenaemia. Lower initial provirus loads were associated with successful humoral immune responses. Unexpectedly, provirus in the buffy-coat cells of two cats that tested negative for the p27 antigen (a marker for viraemia) was also detected. In 597 Swiss cats, comparison of p27 antigen levels with PCR results revealed broad agreement. However, similar to the experimental situation, a significant number of animals (10%) was negative for the p27 antigen and FeLV-positive by PCR. These cats had a mean provirus load 300-fold lower than that of animals testing positive for the p27 antigen. In conclusion, an association between the provirus load and the outcome of FeLV infection was found. Detection of provirus carriers should contribute to further the control of FeLV. In addition, quantification of provirus loads will lead to a better understanding of FeLV pathogenesis and anti-retrovirus protective mechanisms.

Rapid feline immunodeficiency virus provirus quantitation by polymerase chain reaction using the TaqMan fluorogenic real-time detection system

An improved quantitative polymerase chain reaction (qPCR) method based on a combination of real-time detection and the 5'-3' nuclease activity of the Taq DNA polymerase was developed to quantify the provirus load of feline immunodeficiency virus (FIV), a lentivirus of veterinary importance and an animal model for AIDS research. Two fluorogenic probes were designed to detect FIV provirus in genomic DNA of peripheral lymphocytes and tissues infected with different FIV subtypes. The most sensitive assay can detect one copy of FIV provirus. The assay showed excellent precision within-run and between-runs. Comparison of the TaqMan system with a conventional seminested PCR assay revealed a comparable detection limit and good correlation. Furthermore the design of the two probes allowed the detection of various FIV isolates of clade A and B.