Preliminary evaluation of the efficacy of intravenous magnesium sulfate for the treatment of ventricular arrhythmias in 16 dogs.

OBJECTIVE: To evaluate the efficacy of IV magnesium sulfate in decreasing the number of ventricular ectopic beats or convert ventricular tachyarrhythmia to sinus rhythm in dogs. DESIGN: Prospective, observational feasibility study. SETTING: Private referral center. ANIMALS: Sixteen client-owned dogs exhibiting 1 or more of the following: (1) sustained or paroxysmal ventricular tachycardia (heart rate > 180/min), (2) single or multiform ventricular complexes at > 60 ectopies/min. INTERVENTIONS: Pretreatment (T1) blood creatinine and electrolyte concentrations were measured. A 60-second lead II ECG strip and systolic arterial blood pressure (SABP) were recorded. Magnesium sulfate 0.1 mmol/kg (0.2 mEq/kg) was administered IV over 5 minutes. Five minutes after completion of the magnesium sulfate injection (T2), electrolyte concentrations were measured again. A second 60-second lead II ECG strip and SABP were recorded. The number of ectopic ventricular and supraventricular beats (sinus beats) that occurred in 60 seconds during the T1 and T2 ECG recordings was compared. T1 and T2 electrolytes and SABP were also compared. RESULTS: There was an increase in the ionized magnesium concentration, a decrease in the heart rate and the number of ventricular ectopic beats, and an increase in the number of supraventricular beats at T2. Two dogs converted to a sinus rhythm at T2 that was not sustained. CONCLUSIONS: Intravenous administration of 0.1 mmol/kg (0.2 mEq/kg) magnesium sulfate in dogs with ventricular ectopy decreased the number of ventricular beats and heart rate. However, a specific conclusion regarding the use of magnesium sulfate as a first-line therapy for dogs with ventricular tachyarrhythmias at the investigated dose cannot be made.

Evaluation of coagulation status in dogs with naturally occurring canine hyperadrenocorticism.

OBJECTIVE: To determine whether or not there are differences in coagulation parameters (eg, thrombelastography [TEG], activated partial thromboplastin time [aPTT], prothrombin time [PT], and fibrinogen) among dogs with naturally occurring hyperadrenocorticism (HAC), dogs with HAC undergoing medical management, and dogs without HAC. DESIGN: Prospective, observational study. SETTING: Veterinary teaching hospital. ANIMALS: Forty-six client-owned dogs undergoing adrenal function testing. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Nine dogs were diagnosed with HAC de novo, 19 dogs were presented for therapeutic monitoring of previously diagnosed HAC, and 18 dogs did not have HAC. Variables compared between groups were age, body weight, platelet count, mean platelet volume, serum concentrations of cholesterol, triglycerides, antithrombin, PT, aPTT, fibrinogen, and TEG parameters (eg, alpha angle, R, K, and maximum amplitude [MA]). Dogs with HAC and dogs treated for HAC had higher serum cholesterol than dogs without HAC (P < 0.05). All groups had mean MA greater than the institutional reference interval. There was a weak, positive correlation between hematocrit and MA that was independent of diagnosis (r(2) = 0.266, P = 0.004). CONCLUSIONS: The results of this study do not support the supposition that a significant difference exists in coagulation tendencies between dogs with HAC prior to treatment, dogs with HAC during treatment, and dogs without HAC. This disagreement with the classically accepted notion that HAC leads to a hypercoagulable state could be due to a couple of possibilities. Namely, the link between HAC and hypercoagulability may be relatively weak, or our findings may be the result of a type II error either as a result of a small sample size or the use of coagulation assays that are insensitive to the effects of HAC on the hemostatic system.

Prevalence of select infectious agents in inflammatory aural and nasopharyngeal polyps from client-owned cats.

Benign, inflammatory polyps may affect the nasopharynx and auditory canal of cats. It has been proposed that inflammation induced by infectious disease agents could trigger polyp formation. The objective of this pilot study was to determine the prevalence of feline herpesvirus-1 (FHV-1), feline calicivirus (FCV), Mycoplasma species, Bartonella species and Chlamydophila felis nucleic acids in polyp tissues collected from 30 clinically affected cats. Samples collected from the tympanic bulla from 12 clinically normal cats were also assayed. DNA or RNA of some of the target agents were amplified from samples from 25% of normal cats and 33% of affected cats; however, statistical associations were not detected for individual agent results or grouped results. The study documents that common oropharyngeal or blood borne agents can be detected in the tympanic bullae of normal cats. Failure to consistently amplify RNA or DNA of the select agents from polyp tissues suggests the agents studied were not directly associated with the pathogenesis of this syndrome in the cats tested. Alternately, the inflammatory response may have cleared microbial nucleic acids to undetectable levels by the time of sample collection.

Incidence of and risk factors for diabetes mellitus in cats that have undergone renal transplantation: 187 cases (1986-2005).

OBJECTIVE: To compare incidence of diabetes mellitus in cats that had undergone renal transplantation with incidence in cats with chronic renal failure, compare mortality rates in cats that underwent renal transplantation and did or did not develop diabetes mellitus, and identify potential risk factors for development of posttransplantation diabetes mellitus (PTDM) in cats. DESIGN: Retrospective case series. ANIMALS: 187 cats that underwent renal transplantation. PROCEDURES: Medical records were reviewed. RESULTS: 26 of the 187 (13.9%) cats developed PTDM, with the incidence of PTDM being 66 cases/1,000 cat years at risk. By contrast, the incidence of diabetes mellitus among a comparison population of 178 cats with chronic renal failure that did not undergo renal transplantation was 17.9 cases/1,000 cat years at risk, and cats that underwent renal trans-plantation were 5.45 times as likely to develop diabetes mellitus as were control cats with chronic renal failure. The mortality rate among cats with PTDM was 2.38 times the rate among cats that underwent renal transplantation but did not develop PTDM. Age, sex, body weight, and percentage change in body weight were not found to be significantly associated with development of PTDM. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that cats that undergo renal transplantation have an increased risk of developing diabetes mellitus, compared with cats with chronic renal failure, and that mortality rate is higher for cats that develop PTDM than for cats that do not.