Validation of a commercially available enzyme immunoassay for measurement of plasma antidiuretic hormone concentration in healthy dogs and assessment of plasma antidiuretic hormone concentration in dogs with congestive heart failure

Use of serum osmolality to identify heart disease stage in dogs and relationship to mathematical chloride correction

BACKGROUND

Heart failure-associated hypochloremia can be depletional from diuretics or dilutional from water retention. Serum osmolality reflects water balance but has not been evaluated in dogs with heart disease.

HYPOTHESIS

To determine if serum osmolality is related to heart disease stage and amount of mathematical correction of serum chloride (Cl- ) concentrations in healthy dogs and dogs with myxomatous mitral valve degeneration (MMVD).

ANIMALS

Seventy-seven dogs (20 healthy, 25 Stage B MMVD, 32 Stage C/D MMVD).

METHODS

Serum Cl- concentrations were mathematically corrected. Osmolality was calculated (calOsm) and directly measured by freezing point depression (dmOsm) and compared by Bland-Altman analysis. Biochemical variables and osmolality were compared among healthy, Stage B, and Stage C/D dogs. Correlations were explored between osmolality and biochemical variables. Median and range are presented. P < .05 was considered significant.

RESULTS

The calOsm was different among groups (P = .003), with Stage B (310 mOsm/kg; 306, 316) and C/D dogs (312 mOsm/kg; 308, 319) having higher calOsm than healthy dogs (305 mOsm/kg; 302, 308). Osmolality methods were moderately correlated (P < .0001, rs  = .46) but with proportional bias and poor agreement. The amount of Cl- correction was negatively correlated with calOsm (P < .0001, rs  = -.78) and dmOsm (P = .004, rs  = -.33). Serum bicarbonate concentration was negatively correlated with Cl- (P < .0001, rs  = -.67).

CONCLUSIONS AND CLINICAL IMPORTANCE

Dogs with Stage B and Stage C/D heart disease had higher calOsm than healthy dogs. Osmolality was inversely related to the amount of Cl- correction, which supports its use in assessing relative body water content. Poor agreement between calOsm and dmOsm prevents methodological interchange.

Syndrome of Inappropriate Antidiuretic Hormone Secretion in a Mini-Breed Puppy Associated With Aspiration Pneumonia

A 3-month-old intact male Prague ratter was presented to the emergency service for evaluation of progressive lethargy, weakness, coughing and labour breathing after an episode of resistance to oral deworming. The patient exhibited depression, increased respiratory effort and cyanosis at initial presentation. Results of first diagnostic work-up (complete blood cell count, biochemistry panel and thoracic x-rays) were all consistent with aspiration pneumonia. The puppy was initially treated with balanced isotonic crystalloids, broad spectrum antibiotics, nebulization with thoracic coupage and was transferred to an infant incubator with a sustained FiO2 of 40-50%. Twenty-four hours after ICU admission the patient's condition suffered a worsening and the dog was orthopneic, severely depressed with episodes of intermittent dysphoria and seizuring. New thoracic radiographs and several samples of blood and urine were collected to go further in the diagnostic workup revealing severe hyponatremia, severe plasma hypotonicity, high natriuresis and metabolic acidosis with a worsening of the radiological pulmonary pattern. Based on these new clinical findings a diagnosis of SIADH was established. Emergency treatment with hypertonic 3% saline solution and loop diuretics was started like a sodium supplement and to inhibit water resorption in renal tubules, thus reducing the volume overload. The goal of this treatment was to achieve a progressive and controlled increase of plasma sodium concentration and promoting the excretion of positive body water imbalance. The patient's condition improved clinically over the following days, treatment was progressively discontinued and the dog was discharged 7 days after admission. To the author's knowledge this is the first report of a puppy younger than 12 weeks with respiratory distress developing SIADH associated to aspiration pneumonia.

Diagnosis of diabetes insipidus observed in Swiss Duroc boars

BACKGROUND

Diabetes insipidus (DI) is a rare disease in humans and animals, which is caused by the lack of production, malfunction or dysfunction of the distal nephron to the antidiuretic effect of the antidiuretic hormone (ADH). Diagnosis requires a thorough medical history, clinical examination and further laboratory confirmation. This case report describes the appearance of DI in five Duroc boars in Switzerland.

CASE PRESENTATION

Two purebred intact Duroc boars at the age of 8 months and 1.5 years, respectively, with a history of polyuric and polydipsic symptoms had been referred to the Swine Clinic in Berne. Based on the case history, the results of clinical examination and the analysis of blood and urine, a tentative diagnosis of DI was concluded. Finally, the diagnosis was confirmed by findings from a modified water deprivation test, macroscopic examinations and histopathology. Following the diagnosis, three genes known to be involved in inherited DI in humans were analyzed in order to explore a possible genetic background of the affected boars.

CONCLUSION

The etiology of DI in pigs is supposed to be the same as in humans, although this disease has never been described in pigs before. Thus, although occurring only on rare occasions, DI should be considered as a differential diagnosis in pigs with polyuria and polydipsia. It seems that a modified water deprivation test may be a helpful tool for confirming a diagnosis in pigs. Since hereditary forms of DI have been described in humans, the occurrence of DI in pigs should be considered in breeding programs although we were not able to identify a disease associated mutation.