Determination of the acid-base status in 50 horses admitted with colic between December 1998 and May 1999

The purpose of the present study was to investigate the acid-base status and the concentration of organic acids in horses with colic caused by various disorders. Blood samples were collected from 50 horses with colic and from 20 controls. No intravenous fluids had been given prior to sample collection. Identified causes of colic included gastric ulceration, small intestinal volvulus, cecal intussusception, cecal rupture, colonic impaction, left dorsal colon displacement, right dorsal colon displacement, colonic volvulus, colitis, peritonitis, and uterine torsion. Thirty-seven horses recovered from treatment of colic, 8 horses were euthanized, and 5 died. Most cases were not in severe metabolic acidosis. In previous studies, most horses presented for diagnosis and treatment of colic were in metabolic acidosis and in shock.     

The role of endotoxins in induced ruminal acidosis in calves.

Experimentally induced ruminal acidosis was carried out in 4 calves to investigate the possibility of resorption of endotoxins from Gram negative bacteria originating from the gastro-intestinal tract. The ruminal acidosis was induced by overfeeding of oats and the effect was evaluated by clinical and blood biochemical changes. Blood samples were collected every 2 h for 60 h before and after experimental feeding. The animals showed signs of ruminal acidosis and also the clinical and blood biochemical changes were similar to those seen after experimental endotoxaemia. However, although being less dramatic the changes in many relevant parameters such as an increase in prostaglandin F metabolite levels, body temperature, endotoxins and a decrease in iron indicate that an endotoxaemic state had occurred. The results of the present study show that ruminal acidosis/stasis is linked to resorption of endotoxins from the gastro-intestinal tract causing endotoxaemia/endotoxicosis.     

Simulated small intestinal volvulus in the anesthetized horse

Experimental closed loop small intestinal volvulus was studied in the anesthetized horse. Volvulus was simulated by ligation of the mesenterial veins to a segment of small intestine. Physical signs and hemodynamic, hematologic, clinical chemical, bacteriologic and peritoneal fluid values were examined. Compared to conscious horses anesthesia highly delayed and modified the clinical signs of shock (changes in mucosal colour, dehydration, decreased skin temperature, elevated pulse rate, low blood pressures) and of small intestinal volvulus (altered peristalsis, gastric dilation). Plasma glucose response to shock was also modified by unconsciousness. However, a dose response relationship was indicated between the extent of small intestinal damage and clinical symptoms. The same was applicable to changes in blood pressures, blood acid-base balance, lactate, potassium, chloride, glucose, inorganic phosphorus, creatinine, creatine kinase, red blood cell and total white blood cell counts and serum total protein. The relationship was also indicated in the following peritoneal fluid values: volume, lactate, pH, total white cell counts, alkaline phosphatase and bacteriology. Changes related to shock (insufficient tissue perfusion) were low blood pressures and metabolic acidosis due to anaerobic glycolysis with accumulation of lactic acid. Also low plasma glucose and elevated plasma potassium, creatinine, inorganic phosphorus and creatine kinase were regarded as consequences of shock.     

Blood and ruminal fluid profiles in carbohydrate-foundered cattle.

The relationships of acetylhistamine and histamine to the clinical signs of carbohydrate-induced acidosis were investigated in beef steers. Blood pH and plasma L-lactic acid decreased and serum sodium, serum potassium, ruminal fluid L-lactic acid, ruminal fluid histamine, and ruminal fluid and blood acetylhistamine increased in carbohydrate-engorged steers as compared with the changes in the steers while feeding on pasture (forage-fed steers). Twelve to 14 hours after the steers had become engorged, clinical signs of laminitis ("feedlot founder") were observed in three of six steers. These signs appeared 4 to 6 hours after blood acetylhistamine attained maximal concentration (2.9997 +/- 1.7054 microgram of histamine base/ml of blood) and blood pH decreased to 7.260 +/- 0.026 at 8 hours after engorgement. Blood histamine value reached 0.1298 +/- 0.1095 microgram of histamine base/ml 4 hours after engorgement (8 to 10 hours before the appearance of clinical illness), but had reached maximal concentration 32 hours after engorgement (0.3300 +/- 0.028 microgram of histamine base/ml of blood).     

A Comparison of Simultaneously Collected Arterial, Mixed Venous, Jugular Venous and Cephalic Venous Blood Samples in the Assessment of Blood-Gas and Acid-Base Status in the Dog

Blood samples were collected simultaneously from the pulmonary artery, jugular vein, cephalic vein, and carotid artery in awake dogs. Blood-gas and acid-base values were measured from these blood samples in normal dogs and in dogs after production of metabolic acidosis and metabolic alkalosis. The values obtained from each of the venous sites were compared with those obtained from arterial blood to determine if venous blood from various sites accurately reflected acid-base balance and could therefore be used in the clinical patient. The results of this study demonstrated significant differences between the blood from various venous sites and the arterial site for PCO2 and pH in all acid-base states. Significant differences for standard bicarbonate (SHCO3) were found only when jugular and cephalic venous blood were compared with arterial blood in dogs with a metabolic acidosis. No significant differences were found for BE when blood from the venous sites was compared with arterial blood. The values for pH, HCO3, TCO2, BE, and SHCO3 measured on blood collected at the various venous sites were found to correlate well with those obtained from arterial blood, with a correlation coefficient of 0.99 for HCO3, TCO2, BE, and SHCO3. These correlation coefficients, together with similar values in BE at all collection sites, indicate that, in the dog with normal circulatory status, blood from any venous site will accurately reflect the acid-base status of the patient.     

Endogenous serum insulin concentration in dogs with diabetic ketoacidosis

Objective: To determine endogenous serum insulin concentration in dogs with diabetic ketoacidosis (DKA), and to compare it to endogenous serum insulin concentration in diabetic dogs with ketonuria but no acidosis (KDM), diabetic dogs with uncomplicated diabetes mellitus (DM) that did not have ketonuria or acidosis, and dogs with non‐pancreatic disease (NP). Design: Prospective study. Setting: Veterinary Hospital of the University of Pennsylvania. Animals: Forty‐four client‐owned dogs; 20 dogs with newly diagnosed diabetes mellitus (7 dogs with DKA, 6 dogs with KDM, and 7 dogs with DM) and 24 dogs with non‐pancreatic disease. Interventions: Blood and urine samples were obtained at the time of admission to the hospital. Measurements and main results: Signalment, clinical signs, physical examination findings, and concurrent disease were recorded for all dogs. Blood glucose concentration, venous blood pH, venous blood HCO3^? concentration, urinalysis, and endogenous serum insulin concentration were determined in all dogs. Dogs with DKA have significantly decreased endogenous serum insulin concentrations compared to dogs with DM (P = 0.03) and dogs with non‐pancreatic disease (P = 0.0002), but not compared to dogs with KDM (P = 0.2). Five of 7 dogs with DKA had detectable endogenous serum insulin concentrations, and 2 of these dogs had endogenous serum insulin concentration within the normal range. Conclusions: Diabetic dogs with ketoacidosis have significantly decreased endogenous serum insulin concentration compared to dogs with uncomplicated diabetes mellitus. However, most dogs with DKA have detectable endogenous serum insulin concentrations, and some dogs with DKA have endogenous serum insulin concentrations within the normal range.     

Retrospective evaluation of acute hyperkalemia of unknown origin during general anesthesia in dogs

ObjectiveTo report and characterize cases of acute hyperkalemia of unknown origin in dogs under anesthesia.Study designMulticentric retrospective clinical study.AnimalsMedical records of 19 client-owned dogs that developed acute hyperkalemia during anesthesia.MethodsAnesthetic records of dogs developing acute hyperkalemia from January 2015 to December 2022 were evaluated. Data collected included demographics, duration of anesthesia until the episode, electrolytes and blood gas measurements, electrocardiogram (ECG) abnormalities, drugs used as part of the anesthetic protocol, hyperkalemia treatment and outcome.ResultsA total of 13 cases met the inclusion criteria with documented acute hyperkalemia with no apparent underlying cause during anesthesia. Dogs were [mean ± standard deviation (range)] 6.5 ± 5.0 (3–10) years old and weighed 18.0 ± 14.3 (5.1–40.0) kg. All dogs were administered dexmedetomidine and an opioid as part of the premedication. All dogs had inhalation anesthesia of >60 minutes’ duration. The first clinical sign was bradycardia that was minimally responsive to anticholinergic administration and was often accompanied by moderate/severe hypotension. These signs were rapidly followed by ECG changes compatible with hyperkalemia and/or cardiac arrest. Rapid identification and treatment for hyperkalemia, with or without dexmedetomidine reversal, resulted in survival of 12 dogs and one fatality.Conclusions and clinical relevanceUnknown origin hyperkalemia is a life-threatening complication that can occur during general anesthesia. In healthy dogs, preanesthetic administration of dexmedetomidine in association with an opioid and followed by inhalation anesthesia of more than 1 hour duration may predispose to this complication. A sudden decrease in heart rate >90 minutes after dexmedetomidine administration, or ECG changes, may warrant measurement of blood potassium concentrations.     

Volvulus of the cecum and large colon caused by multiple mesenteric defects in a horse.

A 2-year-old Standardbred colt was examined because of signs of abdominal pain of 12 hours' duration. Clinical signs of disease, including tachycardia and abdominal distention, and rectal palpation findings of distention and thickening of the ventral colon, were consistent with displacement or early strangulation obstruction of the large colon. Surgical exploration revealed volvulus of the large colon around an axis formed by the dorsal mesenteric attachment of the transverse colon. The cecum could be completely exteriorized and lacked the cecocolic ligament and dorsal mesenteric attachments. The dorsal mesenteric attachments of the right ventral and dorsal colons were also lacking. The viscera were repositioned, and the horse was discharged 13 days after surgery. The horse developed severe colic 6 months later and was euthanatized. Mesenteric volvulus and omental adhesions were found at necropsy.     

Effects of limb tourniquet ischemia on local and systemic acid-base and blood gases of cattle.

Effects of forelimb tourniquet ischemia of 90 minute duration were investigated in six bulls aged two to three years. Studies were also conducted up to 150 minutes after release of the tourniquet. Parameters investigated were pH, PCO2, PO2, oxygen saturation and HCO3. In systemic circulation no variations in different parameters were observed during 90 minutes of ischemia. However, significant increase in arterial and venous pH were observed after 30 and 45 minutes of the release of tourniquet, respectively. These increases were accompanied by an increase in HCO3. In the affected limb, ischemia resulted in severe acidosis with a significant increase in PCO2 and a nonsignificant decrease of HCO3. There was a significant fall in PO2 and oxygen saturation. After release of the tourniquet, limb venous pH increased significantly due to a significant fall in PCO2 and a nonsignificant increase in HCO3. A significant increase in the limb venous PO2 and oxygen saturation post tourniquet was observed up to the end of the experiments. There was evidence of very poor oxygen exchange and utilization up to 150 minutes after release of the tourniquet. These results demonstrated that tourniquet ischemia of 90 minutes duration of the limb of cattle may not be safe.     

Investigations on the association of D-lactate blood concentrations with the outcome of therapy of acidosis, and with posture and demeanour in young calves with diarrhoea

The objective of this prospective study was to elucidate whether amounts of bicarbonate needed for correction of acidosis and normalization of clinical signs are influenced by blood D-lactate concentrations in calves with diarrhoea. In 73 calves up to 3 weeks old with acute diarrhoea and base excess values below -10 mmol/l correction of acidosis was carried out within 3.5-h by intravenous administration of an amount of sodium bicarbonate which was calculated using the formula: HCO (mmol) = body mass (kg) x base deficit (mmol/l) x 0.6 (l/kg). Clinical signs, venous base excess, and plasma D-lactate concentrations were monitored immediately following admission, following correction of acidosis at 4 h and 24 h after admission. The base excess and plasma D-lactate concentrations throughout the study were -17.8 +/- 4.0, -0.4 +/- 0.4, -3.0 +/- 5.5 mmol/l (base excess), and 10.0 +/- 4.9, 9.8 +/- 4.8, 5.4 +/- 3.4 mmol/l (D-lactate) for the three times of examination. Metabolic acidosis was not corrected in more than half of the calves (n = 43) by the calculated amount of bicarbonate, whereas the risk of failure to correct acidosis increases with D-lactate concentrations. The study shows that calves with elevated D-lactate concentrations do not need additional specific therapy, as D-lactate concentrations regularly fall following correction of acidosis and restitution of body fluid volume, for reasons that remain unclear. However, calves with distinct changes in posture and demeanour need higher doses of bicarbonate than calculated with the factor of 0.6 in the formula mentioned above probably because of D-hyperlactataemia.     

Simple acid-base disorders

The body regulates pH closely to maintain homeostasis. The pH of blood can be represented by the Henderson-Hasselbalch equation: pH = pK + log [HCO3-]/PCO2 Thus, pH is a function of the ratio between bicarbonate ion concentration [HCO3-] and carbon dioxide tension (PCO2). There are four simple acid base disorders: (1) Metabolic acidosis, (2) respiratory acidosis, (3) metabolic alkalosis, and (4) respiratory alkalosis. Metabolic acidosis is the most common disorder encountered in clinical practice. The respiratory contribution to a change in pH can be determined by measuring PCO2 and the metabolic component by measuring the base excess. Unless it is desirable to know the oxygenation status of a patient, venous blood samples will usually be sufficient. Metabolic acidosis can result from an increase of acid in the body or by excess loss of bicarbonate. Measurement of the "anion-gap" [(Na+ + K+) - (Cl- + HCO3-)], may help to diagnose the cause of the metabolic acidosis. Treatment of all acid-base disorders must be aimed at diagnosis and correction of the underlying disease process. Specific treatment may be required when changes in pH are severe (pH less than 7.2 or pH greater than 7.6). Treatment of severe metabolic acidosis requires the use of sodium bicarbonate, but blood pH and gases should be monitored closely to avoid an "overshoot" alkalosis. Changes in pH may be accompanied by alterations in plasma potassium concentrations, and it is recommended that plasma potassium be monitored closely during treatment of acid-base disturbances.     

Contemporary approach to acid-base balance and its disorders in dogs and cats

The issue of the acid-base balance (ABB) parameters and their disorders in pets is rarely raised and analysed, though it affects almost 30% of veterinary clinics patients. Traditionally, ABB is described by the Henderson-Hasselbach equation, where blood pH is the resultant of HCO3- and pCO2 concentrations. Changes in blood pH caused by an original increase or decrease in pCO2 are called respiratory acidosis or alkalosis, respectively. Metabolic acidosis or alkalosis are characterized by an original increase or decrease in HCO3- concentration in the blood. When comparing concentration of main cations with this of main anions in the blood serum, the apparent absence of anions, i.e., anion gap (AG), is observed. The AG value is used in the diagnostics of metabolic acidosis. In 1980s Stewart noted, that the analysis of: pCO2, difference between concentrations of strong cations and anions in serum (SID) and total concentration of nonvolatile weak acids (Atot), provides a reliable insight into the body ABB. The Stewart model analyses relationships between pH change and movement of ions across membranes. Six basic types of ABB disorders are distinguished. Respiratory acidosis and alkalosis, strong ion acidosis, strong ion alkalosis, nonvolatile buffer ion acidosis and nonvolatile buffer ion alkalosis. The Stewart model provides the concept of strong ions gap (SIG), which is an apparent difference between concentrations of all strong cations and all strong anions. Its diagnostic value is greater than AG, because it includes concentration of albumin and phosphate. The therapy of ABB disorders consists, first of all, of diagnosis and treatment of the main disease. However, it is sometimes necessary to administer sodium bicarbonate (NaHCO3) or tromethamine (THAM).     

Hyperkalemic periodic paralysis in horses

Eleven horses (3 mares, 7 stallions, 1 gelding) with clinical and biochemical evidence of hyperkalemic periodic paralysis were studied. Each horse had history of episodic weakness, muscular tremors, or collapse, which lasted for periods of a few minutes to hours. Diagnosis was based on hyperkalemia in association with a spontaneous episode of paralysis or by precipitation of an episode by oral administration of potassium chloride. Clinical and biochemical events were documented during spontaneous and induced episodes of muscular weakness. During episodes, electrocardiographic findings were consistent with hyperkalemia. Electromyography performed between episodes revealed fibrillation potentials and positive sharp waves, complex repetitive discharges, and myotonic discharges. Histologic changes in muscle biopsy specimens varied from no overt changes in some horses to vacuolation in type-2B fibers with mild degenerative changes in other horses. Electron microscopy of myofibers revealed dilatations of the sarcoplasmic reticulum. Analysis of blood samples taken serially during induced attacks in 5 horses revealed marked hyperkalemia (5.5 to 9.0 mEq/L), with normal acid-base status, hemoconcentration, and modest changes in muscle-derived enzymes. Close correlation (r2 = 0.882) between total plasma protein and plasma potassium concentrations was observed and indicated a shift of fluid out of the extracellular fluid compartment. Treatment of either spontaneous or induced episodes by IV administration of calcium, glucose, or bicarbonate resulted in rapid recovery. Dietary management or daily administration of acetazolamide effectively controlled episodes. An affected mare was bred to an affected stallion, and 3 affected offspring were produced by embryo transfer. Blood samples from another extended family of affected horses were analyzed for identification of a genetic marker.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effect of propofol on acid-base balance and ionic composition of venous and arterial blood in goats

The aim of the present study was to determine the effect of propofol on acid-base balance and ionic composition of arterial and venous blood in clinically healthy goats. The experiment was performed on ten adult goats. Propofol was administered intravenously at bolus dose of 6 mg/kg bw. The heart and breath rate, acid-base balance (pH, pCO2, pO2, HCO3-, BE, O2SAT, ctCO2) and ionic composition (Na+, K+, Cl-) of arterial and venous blood were measured before injection and 3, 6 and 15 min. after. The propofol infusion induced increase of heart rate, decrease of breath rate and compensated respiratory acidosis in venous and arterial blood. It was found that changes of acid-base balance parameters in arterial blood arose faster than in venous blood. The levels of sodium and chloride ions in both types of blood were similar, whereas the level of potassium ions was higher in venous blood during entire experiment.     

氨氟醚吸入麻醉妊娠犬及其胎儿动脉血药浓度和血气分析

选用 10只妊娠犬 ,实施母体及胎儿股动脉血管插管后 ,测定了氨氟醚麻醉期间母犬及胎儿的动脉血药浓度和血液 p H、PO2 (动脉氧分压 )、PCO2 (动脉 CO2 分压 )、T- CO2 (血浆 CO2 总量 )、HCO- 3 (实际碳酸氢盐 )、SB(标准碳酸氢盐 )、BEb(全血碱超 )、Sat.O2 (血氧饱和度 )。结果 :氨氟醚可透过胎盘进入胎儿血液 ,胎儿血药浓度低于母犬 ,但两者上升和消除变化趋势接近 ;麻醉期间 ,母犬及胎儿血液 p H、BEb下降 (P<0 .0 1或 P<0 .0 5 ) ,PO2 、PCO2 、Sat.O2 升高(P<0 .0 1或 P<0 .0 5 ) ,HCO- 3 、T- CO2 表现升高趋势 (P>0 .0 5 ) ,SB表现下降趋势 (P>0 .0 5 )。结果表明 ,氨氟醚吸入麻醉期间 ,母犬及其胎儿呈现轻度呼吸性酸中毒和代谢性酸中毒并存 ,并随氨氟醚血药浓度的降低而逐渐恢复     

Volvulus of the large colon in a neonatal foal

A one‐day‐old Thoroughbred colt foal was presented for assessment of abdominal pain and reduced urine output. Physical examination of the foal revealed marked abdominal distension, mild tachycardia, tachypnoea and congested mucous membranes. A marked anechoic peritoneal effusion, intestinal hypomotility and mural thickening of the large colon were detected sonographically. Serosanguinous fluid was obtained by abdominocentesis. After haemodynamic stabilisation, the foal underwent general anaesthesia and exploratory laparotomy and a 720° volvulus of the large colon at the sternal and diaphragmatic flexures was identified. After correction of the volvulus, the intraoperative findings were consistent with nonviability of the affected portion of the colon. The owner declined partial colon resection and elected for euthanasia of the foal. Although rare in neonatal foals, large colon volvulus should be considered in foals with signs of abdominal pain, abdominal distension and ultrasonographic findings of colonic mural thickening and luminal distension.     

Comparison of Naturally Occurring Proximal Duodenal Obstruction and Abomasal Volvulus in Dairy Cattle

Physical and clinicopathologic findings from six cows with proximal duodenal obstruction (PDO) and 58 cows with abomasal volvulus (AV) were compared retrospectively. Many of the physical signs were similar in cows with PDO and cows with AV, but the two conditions differed in the type of abdominal distention, and in the findings from rectal examination and abdominal auscultation. Cows with PDO had significantly lower mean values for serum sodium (Na+) and chloride ion (Cl-), and higher mean values for plasma bicarbonate [HCO3-], base excess, carbon dioxide pressure (pCO2), serum phosphate, urea nitrogen, and total protein than AV affected cattle. Cows with PDO showed hyperglycemia (range, 263-990 mg/dl; mean, 618 mg/dl) of unexplained etiology that was significantly higher than blood-glucose concentrations in AV cows (mean, 178 mg/dl). Although all AV cows with anion gap values greater than 32 mEq/l died;PDO cows with equally elevated anion gap survived. The anion gap elevations in PDO and AV cows resulted from accumulation of different anions. Although the site of obstruction of aborad flow of ingesta is similar in both disease conditions, the differences in physical and clinicopathologic findings appear to reflect differences in the degree of reticulo-omasal orifice obstruction and the degree of abomasal vascular compromise.     

Alteration in blood gases in cats naturally infected with Aelurostrongylus abstrusus

Four cats were presented with respiratory signs and first-stage larvae of Aelurostrongylus abstrusus were found in faecal samples. Anthelmintic treatment was given to the infected cats and venous blood gases were analysed during the treatment period. Blood gas analysis suggested hypoventilation and respiratory acidosis in infected cats. Hypoventilation may be the result of airway obstruction by adults and larvae in respiratory bronchioles and the alveolar canals. The blood gas values had returned close to the physiological range by two months after treatment. Assessment of respiratory acidosis may aid development of additional treatment methods in cats infected with A. abstrusus.     

The applicable merit of untreated, HCl-treated and partly-hydrolysed straw meal in the feeding regimen of piglets after early weaning. 4. Histological findings in the digestive epithelium of the piglet

In studies with piglets of the country race the applicability of variously treated straw materials was tested in comparison with conventional concentrate feeding (I) after an early weaning date (30th-35th day of life) over an 8-week period (1st-8th week of keeping). In the rations containing 10% straw (straw-concentrate mixtures), untreated (II), HCl treated (III: HCl treatment without steaming) and partly hydrolyzed straw meal (IV: HCl treatment with subsequent steaming) were used in the feeding. Samples were taken of 4 killed animals each in the 2nd and 8th weeks of keeping for the qualitative histologic assessment of palatum durum, oesophagus and stomach, duodenum and caecum, colon ascendens, colon descendens and rectum. Although significantly lower pH values in the stomach were registered after the feeding of feed mixtures III and IV due to increased acidity (pH value decrease by 1.3 to 1.5 units) in comparison to the values in I and II, the lamina epithelialis of the palatum durum remained intact in all groups and without any signs of cauterization. Equally, considerable changes in the comparison of the feeding groups could not be detected in the structures of the oesophagus and the stomach walls or in the qualitative histologic assessment of the duodenum and the caecum. However, there were clearly distinguishable group specifics with regard to the formation of lymphoreticular tissue in the stomach and for the colon ascendens.(ABSTRACT TRUNCATED AT 250 WORDS)