Characterization of the clinical characteristics, electrolytes, acid–base, and renal parameters in male cats with urethral obstruction

Objective: To characterize the clinical characteristics, electrolyte changes, acid–base changes, and renal parameters in a consecutive population of cats with urethral obstruction. Design: Retrospective clinical study. Setting: University Veterinary Teaching Hospital. Animals: Two hundred and twenty‐three male cats that presented consecutively with urethral obstruction between 1997 and 1999. Interventions: None. Measurements and main results: The medical records of 223 cats with urethral obstruction were reviewed for signalment, previous medical history, indoor/outdoor status, body weight, clinical signs, physical examination findings, renal function tests (blood urea nitrogen and creatinine), and blood gas and electrolyte analysis. The majority of cats were relatively stable without serious metabolic derangements. Only 12% (24/199) of cats had severe hyperkalemia (>8.0 mmol/L). Hyperkalemia did not occur in isolation; the majority of these cats had concurrent acidemia and low ionized calcium concentrations. Potassium was significantly inversely correlated with pH, bicarbonate, pCO₂, sodium, chloride, and ionized calcium, but positively correlated with blood urea nitrogen and creatinine. Ionized calcium was positively correlated with pH and bicarbonate. Of the animals with a potassium concentration greater than 8.0 mmol/L, 75% (18/24) had an ionized calcium concentration of less than 1.0 mmol/L. Seventy‐nine percent (19/24) of cats with a potassium concentration greater than 8.0 mmol/L had a blood pH<7.20. Similarly, 74% (23/31) of cats with a pH<7.20 had an ionized calcium concentration <1.00 mmol/L. Conclusions: The majority of cats with urethral obstruction presented with mild electrolyte and blood gas changes and were relatively stable, although 12% of cats had multiple, life‐threatening metabolic derangements. Of 219 cats in this study, 205 (93.6%), where it could be determined, survived to discharge from the hospital, supporting the fact that most cats with urethral obstruction survive the acute episode with emergency treatment.     

Acid-base and biochemical stabilization and quality of recovery in male cats with urethral obstruction and anesthetized with propofol or a combination of ketamine and diazepam

This study compared acid-base and biochemical changes and quality of recovery in male cats with experimentally induced urethral obstruction and anesthetized with either propofol or a combination of ketamine and diazepam for urethral catheterization. Ten male cats with urethral obstruction were enrolled for urethral catheterization and anesthetized with either ketamine-diazepam (KD) or propofol (P). Lactated Ringer’s solution was administered by intravenous (IV) beginning 15 min before and continuing for 48 h after relief of urethral obstruction. Quality of recovery and time to standing were evaluated. The urethral catheter was maintained to measure urinary output. Hematocrit (Hct), total plasma protein (TPP), albumin, total protein (TP), blood urea nitrogen (BUN), creatinine, pH, bicarbonate (HCO₃⁻), chloride, base excess, anion gap, sodium, potassium, and partial pressure of carbon dioxide in mixed venous blood (pvCO₂) were measured before urethral obstruction, at start of fluid therapy (0 h), and at subsequent intervals. The quality of recovery and time to standing were respectively 4 and 75 min in the KD group and 5 and 16 min in the P group. The blood urea nitrogen values were increased at 0, 2, and 8 h in both groups. Serum creatinine increased at 0 and 2 h in cats administered KD and at 0, 2, and 8 h in cats receiving P, although the values were above the reference range in both groups until 8 h. Acidosis occurred for up to 2 h in both groups. Acid-base and biochemical stabilization were similar in cats anesthetized with propofol or with ketamine-diazepam. Cats that received propofol recovered much faster, but the ketamine-diazepam combination was shown to be more advantageous when treating uncooperative cats as it can be administered by intramuscular (IM) injection.     

Characterization and treatment of acid-base and renal defects due to urethral obstruction in cats

In 23 cats, urinary obstruction of 24 to 48 hours' duration caused marked azotemia, hyperphosphatemia, hyperkalemia, and metabolic acidosis. The metabolic acidosis was a consistent finding and was severe in all cats (venous pH, 7.11 +/- 0.09). Serum sodium and chloride were normal. Glycosuria was found in 17 (74%) of the cats. There was no clear difference in blood pH, serum chemical values, or electrolyte concentrations between cats obstructed 24 hours and those obstructed 48 hours or longer. At a mean of 8.4 hours after relief of obstruction, acid-base status was corrected to normal, using fluid replacement and sodium bicarbonate therapy. Blood urea nitrogen serum creatinine, and serum inorganic phosphorus improved significantly (P less than 0.01) at a mean of 19.5 hours after treatment. Variation in azotemia after fluid replacement suggested variable decreases in glomerular filtration rate after relief of obstruction. Hypokalemia occasionally developed after relief of obstruction during the postobstructive diuresis. It was concluded that fluid and electrolyte therapy must be regulated in response to the postobstructive diuresis, to ensure proper medical management.     

Effect of a 24-hour infusion of an isotonic electrolyte replacement fluid on the renal clearance of electrolytes in healthy neonatal foals

OBJECTIVE: To determine the effects of a 24-hour infusion of an isotonic electrolyte replacement fluid (IERF) on weight, serum and urine electrolyte concentrations, and other clinicopathologic variables in healthy neonatal foals. ANIMALS: 4 healthy 4-day-old foals. DESIGN: Prospective study. PROCEDURE: An IERF was administered to each foal at an estimated rate of 80 mL/kg/d (36.4 mL/lb/d) for 24 hours. Body weight was measured before and after the infusion period. Urine was collected via catheter during 4-hour periods; blood samples were collected at 4-hour intervals. Variables including urine production; urine and serum osmolalities; sodium, potassium, and chloride concentrations in urine and serum; urine and serum creatinine concentrations; urine osmolality-to-serum osmolality ratio (OsmR); transtubular potassium gradient (TTKG); and percentage creatinine clearance (Cr(cl)) of electrolytes were recorded at 0, 4, 8, 12, 16, 20, and 24 hours during the infusion period. Immediately after the study period, net fluid and whole-body electrolyte changes from baseline values were calculated. RESULTS: Compared with baseline values, urine and serum sodium and chloride serum concentrations, urine and serum osmolalities, OsmR, and percentage Cr(cl) of sodium and chloride were significantly increased at various time points during the infusion; urine production did not change significantly. After 24 hours, weight, TTKG, serum creatinine concentration, and whole-body potassium had significantly decreased from baseline values. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that administration of an IERF containing a physiologic concentration of sodium may not be appropriate for use in neonatal foals that require maintenance fluid therapy.     

Serum concentrations of parathyroid hormone and 25-OH vitamin D3 in cats with urethral obstruction

Objective: To measure serum parathyroid hormone (PTH) and 25‐hydroxyvitamin D₃ concentrations in cats with urethral obstruction. Design: Prospective single cohort study. Setting: University affiliated veterinary teaching hospital. Animals: Male cats with urethral obstruction. Interventions: Routine blood samples drawn from male cats with urethral obstruction. Measurements and main results: Measured variables included blood gas parameters, plasma sodium, potassium, chloride, and ionized calcium concentrations, as well as serum blood urea nitrogen, creatinine, phosphorus, PTH, and 25‐hydroxyvitamin D₃ concentrations. PTH was inversely correlated with ionized calcium and positively correlated with serum phosphorus. No discernable relationship could be found between 25‐hydroxyvitamin D₃ and any of the measured parameters. Conclusions: Lack of parathyroid response does not appear to be the underlying mechanism for ionized hypocalcemia in cats with urethral obstruction.     

Effects of small- and large-volume resuscitation on coagulation and electrolytes during experimental endotoxemia in anesthetized horses

BACKGROUND: Small-volume resuscitation (SVR) has been advocated in place of large-volume isotonic resuscitation for the treatment of endotoxemia in horses. The effects of this type of therapy during experimental endotoxemia on electrolytes and coagulation have not been evaluated in the horse. As part of a larger project, the objective of this study was to determine the effects of SVR (hypertonic saline solution [HSS] plus hetastarch [HES]) on coagulation and serum electrolytes concentration, and to compare SVR with large- and small-volume isotonic resuscitation during experimental endotoxemia in anesthetized horses. HYPOTHESIS: SVR does not affect coagulation parameters or serum electrolyte concentrations when compared with either small- or large-volume isotonic crystalloids. ANIMALS: Horses were randomly assigned to 1 of 3 groups. Under halothane anesthesia, endotoxemia was induced by administering 50 microg/kg Escherichia coli endotoxin i.v. The horses were treated for 30 minutes with 15 mL/kg of balanced polyionic crystalloid solution (control), 60 mL/kg of balanced polyionic crystalloid solution (ISO), or 5 mL/kg of HSS followed by 10 mL/kg HES (HSS-HES). METHODS: Prospective randomized trial. RESULTS: Significant differences in coagulation parameters were not found among the groups. Thrombocytopenia was severe in all 3 groups. Serum ionized calcium concentration significantly decreased from baseline in control and ISO groups but not in the HSS-HES group. CONCLUSIONS AND CLINICAL IMPORTANCE: These results suggest that the HSS-HES combination, at the dosage used in this study had no adverse effects on coagulation beyond those produced by endotoxemia. HSS-HES may have a protective effect against endotoxemia-induced ionized hypocalcemia.     

Urinary acidification in the prevention and treatment of feline struvite urolithiasis

Two groups of 12 cats were fed ad libitum an experimental dry expanded ration high in magnesium (0.37%, dry matter basis) and similar to most commercial dry cat foods in all other nutrients. The diet of one of the groups contained 1.5% ammonium chloride, which was added to the diet before processing. Urethral obstruction developed twice in 7 of the 12 cats fed the ration without ammonium chloride. Of the 5 remaining cats in that group, 2 had calculi in the urinary bladder and urethra at necropsy. In contrast, only 2 of the 12 cats fed the ration containing ammonium chloride had urethral blockage once; neither cat had another blockage. Both cats had been catheterized twice as paired controls before urethral obstruction. One of these 2 cats died from a urinary tract infection apparently introduced through the indwelling catheter, and at necropsy there were 2 small calculi in the urethra. At the end of the study, only 1 other cat fed the ammonium chloride diet had a calculus in the urinary bladder at necropsy; this cat had not had a urethral obstruction throughout the study. After each cat had 2 urethral blockages, its diet was changed. Four cats were fed the ration containing ammonium chloride and 3, a dry, commercial ration. Of the 4 cats fed the diet containing ammonium chloride, none developed another urethral obstruction within 6 months, and at necropsy, no calculi were in the urinary bladder or urethra. Two of the 3 cats fed the commercial ration experienced urethral blockage within 3 months. These 2 cats were then fed the diet containing ammonium chloride.(ABSTRACT TRUNCATED AT 250 WORDS)     

Cardiopulmonary bypass in the cat

OBJECTIVE: To assess the physiologic response to, and acute survival of, cats undergoing cardiopulmonary bypass (CPB) and to evaluate the efficacy of a commercial human pediatric oxygenator system on cats weighing less than 6 kg. STUDY DESIGN: Experimental study. ANIMALS: Six intact male cats METHODS: Cats were placed on cardiopulmonary bypass by cannulating the cranial and caudal vena cavae and the carotid artery. The pediatric CPB circuit was primed with 150 mL of a balanced crystalloid solution. Venous drainage was enhanced by a controlled, vacuum-assist system. A cross-clamp was placed on the ascending aorta and cardiac arrest was induced by antegrade infusion of a cold cardioplegia solution. After 45 minutes of arrest time, the cross-clamp was removed and the cats were weaned off bypass and decannulated. No blood products were administered. Heart rate, mean arterial pressure (MAP), central venous pressure, arterial blood gas, hematocrit (HCT), total plasma protein concentration (TP), serum electrolyte concentrations, and activated clotting time (ACT) were measured at baseline period (BL), during CPB, 60 minutes after CPB (CPB 60) and 90 minutes after CPB (CPB 90). A complete blood count (CBC), blood chemistry profile, and urinalysis were performed at BL, during CPB, and CPB 90. Cats were euthanatized after CPB 90. RESULTS: Cardiopulmonary bypass resulted in a significant (P <.05) decrease in mean HCT (18.0%) and TP (2.3 gm/dL) at CPB 90 when compared to BL (30.5% and 6.0 gm/dL, respectively). The MAP at CPB 90 (54 mm Hg) was decreased from BL (94 mm Hg). The ACT increased from a mean of 124 seconds to > 400 seconds with heparinization and was reversed to 300 seconds with protamine. Mean platelet counts decreased from BL (369,000 /microL) to CPB 90 (94,500 /microL). Mean white blood cell counts decreased from 13,200 /microL at BL to 2,200 /microL at CPB 90. Upon reperfusion, 1 cat fibrillated but was successfully defibrillated. CONCLUSIONS: Cardiopulmonary bypass was performed successfully in 6 cats weighing less than 6 kg. Acute survival to 90 minutes after CPB was achieved in all 6 cats CLINICAL RELEVANCE: The ability to perform CPB in the cat may allow intracardiac repair of various heart defects in this species.     

Food and water intake and urine composition in cats: influence of continuous versus periodic feeding

Twenty healthy, noncastrated, adult male cats had periodic (11 am to 12 am) or continuous (24 hours daily) access to food. With periodic feeding, cats ate less food, drank less water, and produced less urine than when food was available continuously. The composition of urine obtained by cystocentesis at 7:30 am, 3:30 pm, and 10 pm was influenced somewhat by feeding pattern. With periodic feeding, urine pH was lower at 7:30 am and higher at 3:30 pm than it was with continuous feeding. Most mineral concentrations and urine osmolality-specific gravity did not differ with the different feeding schedules. However, when periodic feeding was used, concentrations of magnesium and phosphorus in urine were as high or higher preprandially (7:30 am) than postprandially (3:30 pm). Frequency of urination per 24 hours was not influenced by the feeding schedule, but the time that urination occurred during the 24-hour period was somewhat different. An experimental, high magnesium diet fed to the cats for 200 days caused urethral obstruction in 7 of 10 cats fed periodically and in 7 of 10 cats fed continuously. Cats with obstruction had urinary mineral concentrations similar to concentrations in cats without obstruction, indicating that urinary mineral concentration may not be the only factor relevant to the process of obstruction. Necropsy findings and histologic evaluation of tissues from the cats indicated incidental lesions or abnormalities caused by urethral obstruction, but did not indicate anatomic abnormalities that would have predisposed the cats to obstruction.(ABSTRACT TRUNCATED AT 250 WORDS)     

Cardiovascular and pulmonary effects of hetastarch plus hypertonic saline solutions during experimental endotoxemia in anesthetized horses

BACKGROUND: Small volume resuscitation has been advocated as a beneficial therapy for endotoxemia in horses but this therapy has not been investigated in a prospective manner. The objective of this study was to determine the cardiopulmonary effects of small-volume resuscitation using hypertonic saline solution (HSS) plus Hetastarch (HES) during experimental endotoxemia in anesthetized horses. HYPOTHESIS: Treatment of horses with induced endotoxemia using HES-HSS does not alter the response of various cardiopulmonary indices when compared to treatment with either small- or large-volume isotonic crystalloid solutions. ANIMALS: Eighteen healthy horses were randomly assigned to 1 of 3 groups. Anesthesia was maintained with halothane. Endotoxemia was induced by administering 50 microg/kg of Escherichia coli endotoxin IV. The horses were treated over 30 minutes with 15 mL/kg of balanced polyionic crystalloid solution (control), 60 mL/kg of balanced polyionic crystalloid solution (ISO), or 5 mL/kg of HSS followed by 10 mL/kg of HES (HSS-HES). METHODS: Prospective randomized trial. RESULTS: Cardiac output (CO) after endotoxin infusion increased significantly (P < .05) from baseline in all groups, whereas mean central venous pressure increased significantly (P < .05) in the ISO group only. Mean pulmonary artery pressure increased from baseline (P < .05) in horses treated with isotonic fluids and HSS-HES. There was no effect of treatment with HSS-HES on CO, systemic vascular resistance (SVR), mean arterial pressure, blood lactate concentrations, or arterial oxygenation. CONCLUSIONS AND CLINICAL IMPORTANCE: The use of HSS-HES failed to ameliorate the deleterious hemodynamic responses associated with endotoxemia in horses. The clinical value of this treatment in horses with endotoxemia remains unconfirmed.     

A comparison of four methods of analgesia in cats following ovariohysterectomy

OBJECTIVE: To evaluate the effectiveness of preoperative administration of oral carprofen, subcutaneous ketoprofen, and local nerve block with bupivacaine in preventing postoperative pain-associated behavior in cats after ovariohysterectomy. ANIMALS: Fifty-two female intact cats. Materials and methods Cats received butorphanol (0.44 mg kg(-1) IM), carprofen (2.2 mg kg(-1) PO), ketoprofen (2.2 mg kg(-1) SQ), or bupivacaine infiltration block (1.1 mg kg(-1) SQ) before surgery. Cortisol and drug concentrations and visual analog scale (VAS) and interactive visual analog scale (IVAS) pain-associated behavior scores were measured 2 hours before and 0, 1, 2, 4, 8, 12, and 24 hours after ovariohysterectomy. RESULTS: Cats receiving butorphanol had significantly increased IVAS scores 2 hours after surgery compared with baseline measurements. Cats receiving carprofen, ketoprofen, and bupivacaine had significant increases from baseline in VAS and IVAS scores 1 and 2 hours after surgery. VAS and IVAS scores for cats receiving bupivacaine were significantly greater 1 and 2 hours after surgery than for cats that received butorphanol. Cats receiving carprofen had significant increases in cortisol 1 hour after surgery and significant decreases 24 hours after surgery compared with baseline measurements. CONCLUSIONS AND CLINICAL RELEVANCE: Preoperative carprofen and ketoprofen have effects on pain-associated behavior similar to butorphanol in cats undergoing ovariohysterectomy. Cats receiving bupivacaine blocks may require additional analgesics immediately after surgery.     

Safety and efficacy of high‐dose fomepizole compared with ethanol as therapy for ethylene glycol intoxication in cats

Objective – To determine the safety and efficacy of high‐dose fomepizole compared with ethanol (EtOH) in cats with ethylene glycol (EG) toxicosis. Design – Prospective study. Setting – University veterinary research laboratory. Animals – Thirteen cats. Interventions – Two cats received injections of high‐dose fomepizole (Study 1). Three cats received lethal doses of EG and fomepizole treatment was initiated 1, 2, or 3 hours later (Study 2). Eight cats received a lethal dose of EG and were treated with fomepizole or EtOH (Study 3). Cats treated with fomepizole received 125 mg/kg IV initially, then 31.25 mg/kg at 12, 24, and 36 hours. Cats treated with EtOH received 5 mL of 20% EtOH/kg IV initially, then every 6 hours for 5 treatments, then every 8 hours for 4 treatments. Cats also received fluids and supportive therapy as needed. Measurements and Main Results – Clinical signs were monitored and serial blood analyses performed. Cats receiving fomepizole experienced mild sedation but no biochemical evidence of toxicity. Cats receiving fomepizole for EG intoxication survived if therapy was initiated within 3 hours of EG ingestion. One of the 6 developed acute renal failure (ARF) but survived. Only 1 of the 3 cats treated with EtOH 3 hours following EG ingestion survived; 2 developed ARF and were euthanized. Cats treated 4 hours following EG ingestion developed ARF, whether treated with EtOH or fomepizole. Conclusions – Fomepizole is safe when administered to cats in high doses, prevents EG‐induced fatal ARF when therapy is instituted within 3 hours of EG ingestion, and is more effective than treatment with EtOH.     

Changes in serum glucose,sodium, and tonicity in cats treated for diabetic ketosis

Objective – To examine serum sodium, glucose, and tonicity in cats with diabetic ketosis. Design – Retrospective study. Setting – A university‐based referral hospital. Animals – Cats admitted to the ICU during the period 1998 to 2002 with a diagnosis of diabetic ketosis. Interventions – None. Routine clinical management of diabetes and associated conditions. Measurements – Serum biochemistry assessments. Main Results – Abnormalities of glucose, sodium and serum tonicity (ST) were common in the study group. Serum sodium but not glucose correlated closely with ST. A subset of cats treated with intravenous insulin and an isotonic sodium‐containing solution for 72 hours showed a significant decrease in glucose from admission values at 48 and 72 hours (but not at 24 hours). Serum sodium, potassium, and ST were not significantly different from admission values at any time over the 72‐hour period. However, the relative contribution of individual osmolytes varied over the course of treatment. Although glucose decreased >120% from admission values over the 72‐hour treatment period, the approximately 5% rise in serum sodium that occurred offset the osmotic effect of falling glucose and the overall ST change was <3%. Conclusions – The incidence of osmotic‐mediated neurologic complications during treatment of cats with diabetic ketosis is low in part because the minimal fluctuation in ST during treatment likely prevents the development of osmotic gradients between serum and central nervous system tissues. The use of isotonic sodium‐containing fluids in the treatment of feline diabetes acts to minimize large osmotic shifts by adding sodium to the serum compartment as the glucose concentration falls.     

Effects of enteral and intravenous fluid therapy, magnesium sulfate, and sodium sulfate on colonic contents and feces in horses

OBJECTIVE: To assess changes in systemic hydration, concentrations of electrolytes in plasma, hydration of colonic contents and feces, and gastrointestinal transit in horses treated with IV fluid therapy or enteral administration of magnesium sulfate (MgSO4), sodium sulfate (NaSO4), water, or a balanced electrolyte solution. ANIMALS: 7 horses with fistulas in the right dorsal colon (RDC). PROCEDURE: In a crossover design, horses alternately received 1 of 6 treatments: no treatment (control); IV fluid therapy with lactated Ringer's solution; or enteral administration of MgSO4, Na2SO4, water, or a balanced electrolyte solution via nasogastric intubation. Physical examinations were performed and samples of blood, RDC contents, and feces were collected every 6 hours during the 48 hour-observation period. Horses were muzzled for the initial 24 hours but had access to water ad libitum. Horses had access to hay, salt, and water ad libitum for the last 24 hours. RESULTS: Enteral administration of a balanced electrolyte solution and Na2SO4 were the best treatments for promoting hydration of RDC contents, followed by water. Sodium sulfate was the best treatment for promoting fecal hydration, followed by MgSO4 and the balanced electrolyte solution. Sodium sulfate caused hypocalcemia and hypernatremia, and water caused hyponatremia. CONCLUSIONS AND CLINICAL RELEVANCE: Enteral administration of a balanced electrolyte solution promoted hydration of RDC contents and may be useful in horses with large colon impactions. Enteral administration of either Na2SO4 or water may promote hydration of RDC contents but can cause severe electrolyte imbalances.     

Assessment of blood pressure in cats presented with urethral obstruction

Objective: To determine the arterial blood pressure at presentation in male cats with acute urethral obstruction, and to determine whether there was any correlation between these measurements and concurrent metabolic abnormalities. Design: Prospective, single cohort, observational study. Setting: Private, small animal, after‐hours emergency clinic. Animals: Twenty‐eight client‐owned male cats with acute urethral obstruction and no other known coexisting disease. Interventions: Indirect oscillometric blood pressure measurements obtained before blood sampling and treatment. Measurements and main results: Mean arterial blood pressure (MAP) measurements, physical examination parameters, serum blood urea nitrogen (BUN), creatinine, potassium, phosphorus, total calcium and magnesium concentration, venous pH, lead II electrocardiogram, and urine volume in bladder were evaluated. No cats were hypotensive at presentation; 71% (20/28) were normotensive (median MAP=100 mmHg, range 93–140 mmHg); and 29% (8/28) were hypertensive (median MAP=153 mmHg, range 145–176 mmHg). Compared with hypertensive cats, normotensive cats had significantly lower heart rates (P=0.0201) and lower calcium (P=0.0152). For all 28 cats, MAP correlated with serum potassium and total calcium (P=0.0033). Conclusions: Though potassium and total calcium were inversely and directly correlated respectively with blood pressure in cats with urethral obstruction, none of the cats were hypotensive on presentation. Normotension on admission does not support the absence of biochemical and physical abnormalities in obstructed cats.     

Evaluation of clinical signs and causes of lower urinary tract disease in European cats

OBJECTIVES: To investigate the clinical signs and causes of lower urinary tract disease (LUTD) in 77 cats. METHODS: Cats diagnosed with LUTD over a two-year period were included in the study. RESULTS: The study population comprised 67 male and 10 female cats. Uroliths occurred in 17 of the 77 cats (22 per cent), urethral plugs in eight cats (10 per cent) and urinary tract infection in six cats (8 per cent). In 44 cats (57 per cent), no specific cause for the disease was found and they were classified as having idiopathic LUTD. In two of the 77 cats (3 per cent) no definitive diagnosis was established. Pain was less common in cats with uroliths and haematuria was more often seen in cats with urinary tract infection. At presentation, urethral obstruction was diagnosed in 45 of the 77 cats (58 per cent). CLINICAL SIGNIFICANCE: The causes of LUTD found in cats in this study are similar to those that have been previously documented, and idiopathic LUTD is the most frequent diagnosis. However, the rate of urethral obstruction, particularly in cats with idiopathic LUTD, was higher than in other reports. The cause of this difference is unknown.     

Anticoagulant effects of low-molecular-weight heparins in healthy cats

BACKGROUND: Low-molecular-weight heparin (LMWH) has potential benefit in cats at risk for thromboembolic disease. However, LMWH pharmacokinetics has not been characterized in the cat. Drug effect with LMWH may be evaluated with analysis of factor Xa inhibition (anti-Xa) or thromboelastography (TEG). HYPOTHESIS: Administration of LMWH at previously recommended dosages and schedules to healthy cats will result in inhibition of factor Xa and hypocoagulable TEG. ANIMALS: In vivo research with heparin was performed in 5 purpose-bred cats. METHODS: In a prospective study with randomized crossover design, heparin or placebo was administered. Treatments were unfractionated heparin (UFH), 250 IU/kg q6h; dalteparin, 100 IU/kg q12h; enoxaparin, 1 mg/kg q12h; or 0.9% saline, 0.25 mL/kg q6h. Each drug was administered for 5 consecutive days followed by a minimum washout of 14 days. Baseline and post-treatment analyses included anti-Xa, TEG, and prothrombin time/activated partial thromboplastin time. RESULTS: Mean anti-Xa activity 4 hours after enoxaparin (0.48 U/mL) approached the human therapeutic target (0.5-1.0 U/mL); however, mean trough anti-Xa activity was below detection limits. Mean anti-Xa activity 4 hours after dalteparin was lower, and only 1 cat attained therapeutic target at a single time point. Cats receiving UFH attained target anti-Xa activity and changes in TEG at trough and 4 hours. CONCLUSIONS: Cats have rapid absorption and elimination kinetics with LMWH therapy. On the basis of pharmacokinetic modeling, cats will require higher dosages and more frequent administration of LMWH to achieve human therapeutic anti-factor Xa activity of 0.5-1 U/mL. Peak anti-Xa activity is predicted at 2 hours after administration of LMWH.     

Tolerability of Gemcitabine and Carboplatin Doublet Therapy in Cats with Carcinomas

Background: This study was performed to determine the toxicity of gemcitabine-carboplatin doublet therapy in cats with carcinomas.
Hypothesis: Gemcitabine and carboplatin are safe in tumor-bearing cats.
Animals: Twenty cats with spontaneously occurring carcinomas.
Methods: A cohort of 6 cats received gemcitabine (2 mg/kg IV) on days 1, 8, and 15 and carboplatin (10 mg/kg IV) immediately after gemcitabine on day 1 of a 21-day cycle. A 2nd cohort of 14 cats received carboplatin 4 hours after gemcitabine on day 1 and gemcitabine on day 8 but not day 15. The cycles were repeated every 21 days.
Results: Cats in the 1st cohort received a median of 3.75 cycles per animal (range, 1–6). Two cats (33.3%) developed grade 3 or 4 neutropenia, 1 (16.7%) grade 4 thrombocytopenia, and 1 (16.7%) grade 3 gastrointestinal toxicity. Gemcitabine dose reductions and treatment delays occurred in 1 and 4 cats, respectively. Cats in the 2nd cohort received a median of 2 cycles per animal (range, 0.5–10). Two cats (14.3%) had grade 3 or 4 neutropenia and 1 (7.1%) had grade 3 and 4 gastrointestinal toxicity. One cat required gemcitabine dose reduction and 6 had treatment delays. In the 2nd cohort, of 11 cats with measurable tumors, there was 1 complete response (pancreatic carcinoma) and 1 partial response (squamous cell carcinoma, receiving concurrent nonsteroidal anti-inflammatory drugs).
Conclusions and Clinical Importance: Gemcitabine-carboplatin combination appears moderately well tolerated in tumor-bearing cats. Minimal patient benefit suggests that alternative schedules or combinations of gemcitabine with other agents should be explored.     

Effects of sodium chloride on selected parameters in cats

This study used 36 cats with varying renal insufficiency and physiologic status to evaluate the effect of a food high in sodium chloride (HSC) compared with a low sodium chloride (LSC) food on selected blood parameters and blood pressure. Cats eating the HSC food had an increase in serum creatinine, urea nitrogen, and phosphorus compared with cats eating the LSC food. Also, cats eating the HSC food had increased fractional excretion of calcium and increased fractional shortening during cardiac contraction. There was no effect of food on systolic, diastolic, or mean arterial pressure.     

Doppler echocardiographic effects of medetomidine on dynamic left ventricular outflow tract obstruction in cats

OBJECTIVE: To evaluate the effects of medetomidine on dynamic left ventricular outflow tract (LVOT) obstruction in cats with left ventricular hypertrophy. DESIGN: Clinical trial. ANIMALS: 6 domestic shorthair cats with echocardiographic evidence of dynamic LVOT obstruction. PROCEDURE: Cats were restrained in lateral recumbency, and baseline M-mode and Doppler echocardiographic examinations were performed. An ECG was recorded continuously, and blood pressure was measured indirectly with Doppler instrumentation. Medetomidine (20 microg/kg 19.1 microg/lb]) was then administered i.m., and examinations were repeated 15 minutes later. RESULTS: Significant decreases in heart rate, LVOT velocity, and the LVOT pressure gradient were documented following medetomidine administration. After adjusting for the effects of heart rate by ANCOVA, there were no significant differences in any other systolic or diastolic indices of left ventricular function. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that administration of medetomidine to cats with dynamic LVOT obstruction may result in elimination of outflow tract obstruction; medetomidine may be a suitable sedative and analgesic agent in this subpopulation of cats.