Ventricular systolic dysfunction in dogs diagnosed with hypoadrenocorticism

In human patients with hypoadrenocorticism, a secondary dilated cardiomyopathy is noted that has been reported to resolve with replacement steroid therapy. A similar secondary dilated cardiomyopathy in dogs with hypoadrenocorticism has not been previously described. We present three dogs concurrently diagnosed with hypoadrenocorticism and ventricular dilation with systolic dysfunction. Two dogs were presented with clinical signs consistent with biventricular congestive heart failure and a third dog was presented with signs of acute hypoadrenocorticism without congestive heart failure. All dogs recovered to normal cardiac size and function with therapy. Hypoadrenocorticism should be considered as a differential diagnosis in dogs that present with ventricular dilation and systolic dysfunction if there are other indicators in the clinical and laboratory testing. Additionally, a thorough cardiac evaluation should be recommended for dogs that are found to have a heart murmur at the time of diagnosis of hypoadrenocorticism.     

Urinary cortisol‐creatinine ratio in dogs with hypoadrenocorticism

BackgroundBasal serum cortisol (BSC) ≥2 μg/dL (>55 nmol/L) has high sensitivity but low specificity for hypoadrenocorticism (HA).ObjectiveTo determine whether the urinary corticoid:creatinine ratio (UCCR) can be used to differentiate dogs with HA from healthy dogs and those with diseases mimicking HA (DMHA).AnimalsNineteen healthy dogs, 18 dogs with DMHA, and 10 dogs with HA.MethodsRetrospective study. The UCCR was determined on urine samples from healthy dogs, dogs with DMHA, and dogs with HA. The diagnostic performance of the UCCR was assessed based on receiver operating characteristics (ROC) curves, calculating the area under the ROC curve.ResultsThe UCCR was significantly lower in dogs with HA (0.65 × 10⁻⁶; range, 0.33‐1.22 × 10⁻⁶) as compared to healthy dogs (3.38 × 10⁻⁶; range, 1.11‐17.32 × 10⁻⁶) and those with DMHA (10.28 × 10⁻⁶; range, 2.46‐78.65 × 10⁻⁶) (P < .0001). There was no overlap between dogs with HA and dogs with DMHA. In contrast, 1 healthy dog had a UCCR value in the range of dogs with HA. The area under the ROC curve was 0.99. A UCCR cut‐off value of <1.4 yielded 100% sensitivity and 97.3% specificity in diagnosing HA.Conclusions and Clinical ImportanceThe UCCR seems to be a valuable and reliable screening test for HA in dogs. The greatest advantage of this test is the need for only a single urine sample.     

Effect of dietary potassium and anionic salts on acid–base and mineral status in periparturient cows

Dry cow diets based on grassland forage from intensive production contain high amounts of K and could be responsible for a reduced ability to maintain Ca homoeostasis. The aim of this study was to determine whether a moderate anionic salt supplementation to a forage‐based pre‐calving diet with varying native K content affects the mineral and acid–base status in transition cows. Twenty‐four dry and pregnant Holstein cows, without antecedent episodes of clinical hypocalcemia, were assigned to two diets during the last 4 weeks before estimated calving date. Twelve cows were fed a hay‐based diet low in K (18 g K/kg DM), and 12, a hay‐based diet high in K (35 g K/kg DM). Within each diet, six cows received anionic salts during the last 2 weeks before the estimated calving day. After calving, all cows received the high K diet ad libitum. Blood samples were taken daily from day 11 pre‐partum to day 5 post‐partum. Urine samples were taken on days 7 and 2 pre‐partum and on day 2 post‐partum. The anionic salt did not alter feed intake during the pre‐partum period. Serum Ca was not influenced by the dietary treatments. Feeding pre‐partum diets with low K concentrations induced a reduced metabolic alkalotic charge, as indicated by reduced pre‐partum urinary base–acid quotient. Transition cows fed the low K diet including anionic salts induced a mild metabolic acidosis before calving, as indicated by higher urinary Ca, lower urinary pH and net acid–base excretion. Although serum Ca during the post‐partum period was not affected by dietary treatment, feeding a low K diet moderately supplemented with anionic salts to reach a dietary cation–anion difference close to zero permitted to obtain a metabolic response in periparturient cows without altering the dry matter intake.     

A case‐based review of a simplified quantitative approach to acid‐base analysis

Objective – To present a simplified quantitative approach to acid‐base analysis and to demonstrate its clinical utility. Data Sources – Original research articles and textbooks. Data Synthesis – A simplified quantitative approach to acid‐base analysis is presented, which is derived from the Fencl‐Stewart approach and calculates the magnitude of the effect on the standardized base excess (SBE) of 5 separate variables: (1) a free water effect (marked by sodium concentration), (2) an effect marked by the chloride concentration, (3) an albumin effect, (4) a lactate effect, and (5) a phosphate effect. Six clinical cases with acid‐base abnormalities are presented in which the quantitative approach provides information that is not apparent from the traditional approach. Conclusion – This simplified quantitative approach provides a comprehensive evaluation of complex acid‐base disorders, identifies individual processes and their relative influence on SBE, and aids in the development of an appropriate therapeutic plan.     

Presumptive iatrogenic hypoadrenocorticism induced by high‐dose ketoconazole administration in a dog

A 11‐year‐old male neutered Shih Tzu was referred to a tertiary facility with a history of weight loss, decreased appetite, polydipsia, and lethargy. The dog had a 10‐year history of nonspecific allergic dermatitis and was being treated with 16 mg/kg of ketoconazole q12h for Malassezia dermatitis. Vague gastrointestinal signs, hypocholesterolemia, and lack of a stress leukogram increased suspicion for hypoadrenocorticism (HA). An adrenocorticotropic hormone (ACTH) stimulation test identified hypocortisolemia on pre‐ and post‐ACTH samples and ketoconazole was discontinued. After a short course of corticosteroid treatment, an ACTH stimulation test was repeated and pre‐ACTH cortisol concentration was within the reference range, and the post‐ACTH cortisol concentration was mildly increased. The temporal association between return of adequate adrenocortical cortisol production and discontinuation of ketoconazole led to the conclusion that the dog had developed iatrogenic HA secondary to ketoconazole treatment.     

Calcium homeostasis, acid–base balance, and health status in periparturient Holstein cows fed diets with low cation–anion difference

Forty multiparous Holstein dry cows on d 21 prepartum were randomly allocated to four blocks of 10 cows to examine the effects of reducing the dietary cation–anion difference (DCAD) on calcium homeostasis, acid–base balance, health status, and subsequent lactation performance. The reduced DCADs (Na + K − Cl − S, mEq/kg DM) of + 150,+ 50, − 50, and − 150 were obtained by addition of anionic salts. Reducing DCAD resulted in mild metabolic acidosis as indicated by the sharp decline in urinary pH, and minor reductions in blood pH and HCO₃⁻ concentration. Greater plasma calcium concentration was observed in cows fed diets of − 50 and − 150 DCAD (P < 0.05) than those on + 50 and + 150 DCAD diets. The nadir of plasma calcium level on the day of calving was lower (P < 0.05) than the highest level on d 14 prepartum (8.33 vs. 9.30 mg/dL). Composite colostrum calcium concentration was decreased (P < 0.05) with time on d 1 relative to d 2 postpartum (0.212 vs. 0.174%), and feeding of diet − 150 DCAD induced higher (P < 0.05) composite colostrum calcium content than other three DCAD diets. No case of milk fever occurred for any diets, but feeding the two negative DCAD diets reduced (P < 0.05) retained placenta incidence compared with diet of + 150 DCAD. Dry matter intake, milk yield and compositions of fat, protein, and lactose were non-significantly affected (P > 0.05) by dietary treatments. In conclusion, urinary pH is an effective indicator of extracellular fluid acid–base balance, and feeding negative DCAD in late gestation period is beneficial for dairy cows in blood calcium homeostasis and improvement of health status.     

Effect of cation–anion balance in feed on urine pH in rabbits in comparison with other species

In the present investigation, the impact of diet composition on urine pH in rabbits was compared with previous studies on rabbits, cats, dogs, pigs and horses. A total of 13 dwarf rabbits were fed six different diets with a cation–anion balance (CAB) between ?39 and +320 mmol/kg dry matter (DM) using ammonium chloride (NH₄Cl) as an acidifier. CAB was calculated as follows: CAB (mmol/kg DM) = 49.9*Ca + 82.3*Mg +43.5*Na + 25.6*K ? 59*P ? 62.4*S ? 28.2*Cl; minerals in g/kg DM. Urine, faeces and blood were collected. Urine pH ranged from 5.26 ± 0.22 at a CAB of ?39 mmol/kg DM to 8.56 ± 0.24 at a CAB of +320 mmol/kg DM. A low CAB in the feed reduced blood pH and blood base excess significantly. Renal excretion of Ca, P, Na and Mg and water was significantly higher in rabbits eating acidifying diets. In comparison with other species, rabbits reacted to acidifying diets in a similar way as cats, dogs and pigs. Rabbits on a mildly alkalizing diet, however, had a trend to higher urine pH than other monogastric species on such diets (cats, dogs, pigs, horses).     

Duration of the effects of anionic salts on the acid–base status in cows fed different anionic salts only once daily

Seeing the fact that farm managers in Germany feed anionic salts to transition cows once daily, this study set out to evaluate whether the effects on the acid–base status (ABS) and calcium excretion in urine would persist throughout the entire day beyond this feeding practice. Eleven non-lactating, non-pregnant, Holstein–Friesian-cows with a rumen fistula were administered 2Eq of calcium chloride (CaCl₂/five cows) or calcium sulfate (CaSO₄/six cows) once daily for a period of 1 week. At day 7, blood and urine samples were taken every 4 h starting at 06:00 a.m. before feeding the anionic salts, and then ending at the same time the next day. Feeding anionic salts to the cows induced metabolic acidosis in both of the groups. The changes tended to be greater in CaCl₂-cows. After 12 h, the acidosis lessened and the initial values were reached after 24 h. The CaCl₂-cows, however, still showed signs of compensated metabolic acidosis. The results of the present study showed that feeding anionic salts once daily confined the risk of an interrupted effect of the anionic salts on the acid–base status as well as calcium metabolism after 12 h.     

Evaluation of resting cortisol concentration testing in dogs with chronic gastrointestinal signs

BackgroundResting cortisol concentrations are routinely measured in dogs with chronic gastrointestinal signs to rule out hypoadrenocorticism based on a concentration >2 μg/dL (>55 nmol/L).Hypothesis/ObjectivesTo assess the cross‐sectional prevalence of hypoadrenocorticism in a group of dogs with chronic gastrointestinal signs presented to a referral internal medicine service.AnimalsTwo‐hundred and eighty‐two client‐owned dogs with chronic gastrointestinal signs and with resting cortisol concentration testing performed.MethodsRetrospective review of medical records (final diagnosis, resting cortisol concentration, and adenocorticotropic hormone [ACTH] stimulation test results) of a referral population of dogs between May 2013 and September 2017.ResultsResting cortisol concentration was <2 μg/dL (<55 nmol/L) in 79 patients (28%). Repeated resting cortisol concentration measurements were performed in 28 dogs, and in 8, resting cortisol concentrations remained <2 μg/dL (<55 nmol/L). Post‐ACTH cortisol concentration was <2 μg/dL (<55 nmol/L) in 1 dog, consistent with a diagnosis of hypoadrenocorticism and giving a prevalence estimate of hypoadrenocorticism in this population of dogs of 0.3% (95% confidence interval [95CI], 0.03‐1.5%). In 19 dogs with an initial resting cortisol concentration <2 μg/dL (<55 nmol/L), hypoadrenocorticism was excluded based on a repeat resting cortisol concentration >2 μg/dL (>55 nmol/L). Overall, the most common diagnosis was chronic primary inflammatory enteropathy (176/282, 62.4%), followed by extragastrointestinal neoplasia (17/282, 6%), protein‐losing enteropathy, pancreatitis and megaesophagus (10/282, 3.5% each).Conclusions and Clinical ImportanceAlthough dogs with hypoadrenocorticism can present with chronic gastrointestinal signs, it was the final diagnosis in only 1 of 282 dogs presenting to a referral internal medicine service for signs of chronic enteropathy. Repeated resting cortisol concentration may be considered as a test to try and exclude hypoadrenocorticism.     

Cardiovascular,respiratory, electrolyte and acid–base balance during continuous dexmedetomidine infusion in anesthetized dogs

ObjectiveTo evaluate the cardiovascular, respiratory, electrolyte and acid–base effects of a continuous infusion of dexmedetomidine during propofol–isoflurane anesthesia following premedication with dexmedetomidine.Study designProspective experimental study.AnimalsFive adult male Walker Hound dogs 1–2 years of age averaging 25.4 ± 3.6 kg.MethodsDogs were sedated with dexmedetomidine 10 μg kg^?1 IM, 78 ± 2.3 minutes (mean ± SD) before general anesthesia. Anesthesia was induced with propofol (2.5 ± 0.5 mg kg^?1) IV and maintained with 1.5% isoflurane. Thirty minutes later dexmedetomidine 0.5 μg kg^?1 IV was administered over 5 minutes followed by an infusion of 0.5 μg kg^?1 hour^?1. Cardiac output (CO), heart rate (HR), ECG, direct blood pressure, body temperature, respiratory parameters, acid–base and arterial blood gases and electrolytes were measured 30 and 60 minutes after the infusion started. Data were analyzed via multiple linear regression modeling of individual variables over time, compared to anesthetized baseline values. Data are presented as mean ± SD.ResultsNo statistical difference from baseline for any parameter was measured at any time point. Baseline CO, HR and mean arterial blood pressure (MAP) before infusion were 3.11 ± 0.9 L minute^?1, 78 ± 18 beats minute^?1 and 96 ± 10 mmHg, respectively. During infusion CO, HR and MAP were 3.20 ± 0.83 L minute^?1, 78 ± 14 beats minute^?1 and 89 ± 16 mmHg, respectively. No differences were found in respiratory rates, PaO₂, PaCO₂, pH, base excess, bicarbonate, sodium, potassium, chloride, calcium or lactate measurements before or during infusion.Conclusions and clinical relevanceDexmedetomidine infusion using a loading dose of 0.5 μg kg^?1 IV followed by a constant rate infusion of 0.5 μg kg^?1 hour^?1 does not cause any significant changes beyond those associated with an IM premedication dose of 10 μg kg^?1, in propofol–isoflurane anesthetized dogs. IM dexmedetomidine given 108 ± 2 minutes before onset of infusion showed typical significant effects on cardiovascular parameters.