Mechanical Ventilation of a Dog with Pentobarbital Intoxication

A 9-year old spayed female American bulldog presented 5 hours after ingesting a portion of a recently euthanized sheep carcass. The dog was comatose, intubated and manually ventilated on arrival. On physical examination, the dog had stable cardiovascular parameters but was hypothermic. Cranial nerve reflexes were absent and spinal reflexes were depressed. Mechanical ventilation was initiated and maintained for 18 hours before spontaneous respiration returned. Elevated serum pentobarbital concentration (19.1 mg/ml) confirmed pentobarbital intoxication as the cause of neurological signs. This is the first report of a dog with pentobarbital toxicity that was successfully managed with mechanical ventilation. Neurologic and functional recovery was complete and the dog was discharged 48 hours after admission. (J Vet Emerg Crit Care 2001; 11(1):33–37)     

Nitric Oxide Response in Critically III Dogs

Alterations in nitric oxide (NO)production may play a role in critical illness. Total serum nitrate/nitrite concentrations [SNN (uM/L)], the stable metabolites of NO, have been used as an indirect measure of NO in people, with increased concentrations reported in cases of critical illness. The relationship of nitric oxide (NO) to criticalillness in dgos is unknown. We tested the hypothesis that critically ill intensive care unit (ICU) canine illness in dogs is unknown. We tested the hypothesis that critically ill intesive care unit (ICU) canine patients would have increased SNN as compared to healthy dogs and non-critically ill dogs. An organ failure index score (OFI) was assigned to dogs admitted to the ICU to evaluate trends between disease severtiy and SNN. Critically ill dogs had significantly (p < 0.05) higher SNN (median 10.53) as compared to non-critically ill dogs (median 2.3) and healthy dogs (median 1.92). Critically ill dogs with the most severe disease (as based on OFI) had higher SNN concentrations. Survival of critically ill dogs with SNN of > 15 upon ICU admission (12% survival) was significantly less than survival of critically ill dogs with SNN ≤ 15 (91%) survival).l (Vet. Emerg. & Crit. Care, 9: 195–202, 1999)     

Abnormalities of Serum Magnesium in Critically III Dogs: Incidence and Implications

Serum magnesium (Mg) is an infrequnetly measured electrolyte in small animal patients. Currently, little is known about the prevalence and significance of abnormalities in serum Mg in animals. Therefore, a prospective study was performed to examine the incidence and clinical implications of abnormalities in serum Mg levels in critically ill dogs.
Serum Mg and other electrolytes were measured in 93 normal dogs housed at the Purina Pet Care Center and in 48 ill dogs admitted to a small animal critical care unit. The normal reference range for canine serum Mg was determined to be 1.89 – 2.51 mg/dl. Based on this range, 54% of the critically ill dogs were hypomagnesemic (< 1.89 mg/dl) and 13% were hypermagnesemic (> 2.51 mg/dl). Of the electrolytes measured in these patients, serum Mg had the highest prevalence of abnormal values. Hypomagnesemic patients had a significantly higher incidence of concurrent hypokalemia and hyponatremia (p < 0.05), as well as a longer length of hospitalization (p < 0.05) than their normomagnesemic counterparts. Hypermagnesemic patients were 2.6 times more likely not to survive their illness when compared to patients with normal serum Mg levels.
Abnormalities in serum Mg appear to be common in critically ill dogs. These patients commonly have other concurrent electrolyte abnormalities. Since serum Mg is not routinely measured, the presence of hypokalemia or hyponatremia should alert the clinician to the possibility of coexisting hypomagnesemia. The clinical implications of hypomagnesemia and hypermagnesemia in ill dogs appear to involve prolonged hospitalization and increased mortality, respectively: however, the exact etiology remains undetermined.     

Maximal Ventilation Assessment in Healthy Calves

In order to define a reliable method for estimating maximal ventilation in cattle, 12 healthy calves underwent a rebreathing trial and injections of increasing doses of lobeline, a respiratory analeptic. The effects of these tests on the main ventilatory parameters (tidal volume, VT; respiratory frequency, fRand minute volume,.VE) recorded during the 15 s of maximal response were studied and compared. The sharp rise in.VE(4.8 times higher than the resting value) observed during the rebreathing trial was mainly due to an increase in VT. This rise in ventilation was the highest ever reported in calves. Lobeline dose-dependently enhanced ventilation up to a threshold dose of 0.25 mg/kg, which always produced a maximal response. This maximal response (3.7 times higher than the resting value), reflecting both an increase in fR and VT, was reproducible at an interval of 12 h and was highly correlated with that observed during the rebreathing trial (R = 0.98, P< 0.001). These results suggest that: (1) rebreathing trial is a reliable method to induce and measure maximal ventilation in calves; and (2) lobeline administration (0.25 mg/kg) is a reliable means of accurately estimating this variable. Lobeline administration, unlike the rebreathing trial, is safe and easy to standardize, and the test therefore seems to be the preferred way of studying maximal ventilation in calves.     

Serial Estimation of Survival Prediction Indices Does Not Improve Outcome Prediction in Critically III Dogs with Naturally Occurring Disease

Objective: The objectives of this study were to test the value of adding serial measurements to the Survival Prediction Index (SPI 2), and to investigate whether time trajectories add predictive information beyond measurements at a single point in time.
Design: Prospective clinical trial.
Setting: Intensive care unit at a Veterinary Teaching Hospital.
Animals: 63 critically ill dogs
Interventions: Physiologic data were collected within 24 hours of admission to the ICU (Day 1), and again on Day 3 of hospitalization.
Measurements: The first analysis applied the SPI 2 equation on Day 1 and again on Day3. Then a prediction model was re-estimated using Day 1 measurements, and the incremental predictive value of adding Day 1 to Day 3 change scores was evaluated. the third analysis tested the incremental predictive value of change scores in models containing only one prognostic variable. The final analysis compared the re-estimated Day 1 model to an analogously re-estimated Day 3 model.
Main Results: Using the SPI 2 equation, the AUC was 7.7% higher using Day 3 measurements than that obtained using Day 1 measurements (P = 0.515). Starting with the re-estimated Day 1 model (AUC = 0.925), forward stepwise addition of the difference score for each variable did not result in an improvement in the AUC. The AUC for the re-estimated Day 1 model was not statistially different from that of the re-estimated model using Day 3 measurements.
Conculusion: This study shows no benefit to repeated calculation of the SPI 2 later in hospitalization.     

Oxygen-Tension Based Indices as Predictors of Survival in Critically III Dogs: Clinical Observations and Review

With respiratory therapy in critically ill veterinary patients becoming more commonplace, a consistent Indicator of pulmonary function status is necessary. Although calculation of the pulmonary shunt fraction correlates well with the degree of pulmonary dysfunction, lts detetmination requires placement of a pulmonary arterial catheter, an invasive procedure that may not be practical in many clinical situations. Using Information obtained from the atterial blood gas, many other oxygen-tension derived Indices have been suggested as noninvasive measurements of the efficiency of pulmonary gas exchange, lncluding the alveoiar-arterial oxygen tension difference, the ratio of arterial to alveolar oxygen tension, the ratio of arterial to inspired oxygen tension, and the ratio of alveolar-arterial gradient to arterial oxygen tension. A total of 427 blood gas values from 195 different patients were evaluated. A loglstic regression model using a stepwise algorithm was constructed to assess potential multicollinearity and interaction between factors. The only factors that contributed significantly to the model predictive of survival were age (p < 0.015), base excess (p < 0.029), and the alveolar-arterial oxygen tension difference (p < 0.014).     

Initial Experience with Norepinephrine Infusion in Hypotensive Critically III Foals

Seven critically ill foals that continued to be hypotensive despite fluid resuscitation and the infusion of dobutamine and/or dopamine were treated with an infusion of norepinephrine (noradrenaline). The norepinephrine was administered concurrently with dobutamine, and the combination therapy was titrated by use of indirect mean arterial pressure measurements. The highest dose of norepinephrine used was 1.5 mcg/kg/min. In six foals the administration of norepinephrine was associated with an increase in blood pressure. In one foal the mean arterial pressure did not increase in response to the doses of norepinephrine administered. All of the foals experienced an increase in urine output coincident with the start of the norepinephrine infusion. Three of the foal survived to hospital discharge.     

Anemia Is Associated with Decreased Survival Time in Dogs with Lymphoma

Background: Anemia is a common complication in human patients with neoplasia and has been associated with decreased survival time and a poorer quality of life.
Hypothesis: The presence of anemia at diagnosis is negatively associated with survival and remission times in dogs with lymphoma, but not in dogs with osteosarcoma.
Animals: Eighty-four dogs with lymphoma and 91 dogs with osteosarcoma that presented for treatment at the Animal Cancer Center, Colorado State University.
Methods: Retrospective, case-control study. Medical records were reviewed to determine the presence or absence of anemia (PCV < 40) at initial presentation. Median survival and remission times were identified by the Kaplan-Meier product limit method and the association between anemia and survival was determined by a multivariable Cox proportional hazard regression analysis.
Results: Cancer-related anemia is more frequent in dogs with lymphoma than in control dogs or dogs with osteosarcoma. Dogs with lymphoma and anemia had a significantly decreased survival time compared with dogs without anemia. There was no effect of anemia on remission time in dogs with lymphoma. Anemic dogs with osteosarcoma did not have decreased survival or remission time compared with nonanemic dogs with osteosarcoma.
Conclusions and Clinical Importance: Shortened survival time in dogs with lymphoma and anemia at initial presentation has important prognostic significance. Understanding cancer-related anemia in dogs might offer new opportunities to improve quality of life and survival times in these patients.     

Cervical Myelopathy Associated with Extradural Synovial Cysts in 4 Dogs

Three Mastiffs and 1 Great Dane were presented to the University of Wisconsin Veterinary Medical Teaching Hospital for cervical myelopathy based on history and neurologic examination. All dogs were males and had progressive ataxia and tetraparesis. Degenerative arthritis of the articular facet joints was noted on survey spinal radiographs. Myelography disclosed lateral axial compression of the cervical spinal cord medial to the articular facets. Extradural compressive cystic structures adjacent to articular facets were identified on magnetic resonance imaging (1 dog). High protein concentration was the most important finding on cerebrospinal fluid analysis. Dorsal laminectomies were performed in all dogs for spinal cord decompression and cyst removal. Findings on cytologic examination of the cystic fluid were consistent with synovial fluid, and histopathologic results supported the diagnosis of synovial cysts. All dogs are ambulatory and 3 are asymptomatic after surgery with a follow-up time ranging from 1 to 8 months. This is the 1st report of extradural synovial cysts in dogs, and synovial cysts should be a differential diagnosis for young giant breed dogs with cervical myelopathy.     

Pharmacokinetics of Oleandomycin in Dogs After Intravenous or Oral Administration Alone and After Pretreatment With Metamizole or Dexamethasone

The pharmacokinetics of oleandomycin OLD) after intravenous and oral administration, both alone and after intramuscular pretreatment with metamizole or dexamethasone, were studied in healthy dogs. After intravenous injection of OLD alone 10 mg/kg as bolus), the elimination half-life t _1/2, volume of distribution V _{d, area}), body clearance CL_B) and area under the concentration-time curve AUC) were 1.60 h, 1.11 L/kg, 7.36 ml/kg)/min and 21.66 µg h/ml, respectively. There were no statistically significant differences following pretreatment with metamizole or dexamethasone. After oral administration of OLD alone, the t _frac12;, maximum plasma concentrations C _max), time of C _max t _max), mean absorption time MAT) and absolute bioavailability F _abs) were 1.68 h, 5.34 µg/ml, 1.5 h, 1.34 h and 84.29%, respectively. Pretreatment with metamizole caused a significantly decreased value for C _max 2.93 µg/ml) but the MAT value 2.23 h) was significantly increased. Statistically significant changes in the pharmacokinetic parameters of OLD following oral administration were also observed as a result of pretreatment with dexamethasone. The C _max was increased 8.24 µg/ml) and the t _max 0.5 h) and MAT 0.45 h) were lower.     

Bacterial Urinary Tract Infections Associated with Transitional Cell Carcinoma in Dogs

Background

Urinary tract infections (UTI) are believed to be common in dogs with transitional cell carcinoma (TCC), but incidence and contributing factors have not been reported.

Objectives

To determine the frequency and bacterial agents associated with UTI in dogs with TCC and define contributing factors.

Animals

Eighty‐five dogs with a history of urogenital TCC undergoing treatment with chemotherapy that had at least 1 urine culture performed.

Methods

Medical records and culture results were retrospectively reviewed and ultrasound images were reviewed when available. Clinical factors were evaluated statistically for association with positive culture.

Results

Fifty‐five percent (47/85) of dogs had at least 1 positive culture during the course of treatment. Female dogs (80%, 40/50) were more likely than male dogs (29%, 10/35) to have at least 1 positive culture. Ultrasound examination determined that female dogs were more likely to have urethral (74%, 31/42) or trigonal tumor involvement (71%, 30/42) compared to male dogs (32%, 9/28 and 43%, 12/28, respectively). The most commonly isolated organisms were Staphylococcus spp. (23.9%, 29/121) and Escherichia coli (19.8%, 24/121). Dogs with urethral involvement of TCC were significantly more likely to have at least 1 positive culture than dogs without urethral involvement (75%, 30/40 versus 30%, 9/30).

Conclusions

Urinary tract infection is common in dogs with TCC highlighting the importance of regular monitoring for bacterial cystitis in dogs with TCC. In addition, clinical factors such as tumor location and sex may be predictive of positive culture and can help clinicians assess the risk of UTI.