Timothy B. Hackett

Prevalence of Enteric Pathogens in Dogs of North-Central Colorado

To evaluate the prevalence of enteric pathogens in dogs of north-central Colorado, fecal samples were obtained from client-owned dogs presented to the Veterinary Teaching Hospital at Colorado State University for evaluation of acute small-bowel, large-bowel, or mixed-bowel diarrhea (n=71) and from age-matched, client-owned, healthy dogs (n=59). Infectious agents potentially associated with gastrointestinal disease were detected in 34 of 130 (26.1%) fecal samples. Agents with zoonotic potential were detected in feces from 21 (16.2%) of 130 dogs and included Giardia spp. (5.4%), Cryptosporidium parvum (3.8%), Toxocara canis (3.1%), Salmonella spp. (2.3%), Ancylostoma caninum (0.8%), and Campylobacter jejuni (0.8%). Positive test results occurred in dogs with or without gastrointestinal signs of disease. Dogs, particularly those in homes of immunocompromised humans, should be evaluated for enteric zoonotic agents.

Survival of Mycoplasma haemofelis and ‘Candidatus Mycoplasma haemominutum’ in blood of cats used for transfusions

Blood transfusions are commonly administered to cats; associated risks include the transmission of various infectious diseases including Mycoplasma haemofelis (Mhf) and ‘Candidatus Mycoplasma haemominutum’ (Mhm). Blood transfusions in citrate-phosphate-dextrose-adenine (CPDA-1) solution are commonly administered immediately or stored for up to 1 month prior to administration. It is unknown whether Mhf or Mhm survive in this solution or temperature. The purpose of this study was to determine if Mhf or Mhm remain viable after storage in CPDA-1 for varying periods of time. The results provide evidence that transmission of hemoplasmas to naïve cats occurs after administration of infected feline blood that has been stored in CPDA-1 solution for 1 h (Mhf) and 1 week (Mhm). These findings support the recommendation that cats used as blood donors be screened for Mhf and Mhm infections by polymerase chain reaction (PCR) assay prior to use.

Polymerized bovine hemoglobin decreases oxygen delivery during normoxia and acute hypoxia in the rat.

Hemoglobin-based oxygen carriers (HBOC) have been primarily studied for blood loss treatment. More recently infusions of HBOC in euvolemic subjects have been proposed for a wide variety of potential therapies in which increased tissue oxygenation would be beneficial. However, compared with the exchange transfusion models to study blood loss, less is known about HBOC oxygen delivery and vasoacitvity when it is infused in euvolemic subjects. We hypothesized that HBOC [polymerized bovine hemoglobin (PBvHb)] infusion creating hypervolemia would increase oxygen delivery to tissues during acute global hypoxia. Vascular oxygen content and hemodynamics were determined after euvolemic rats were infused with 3 ml of either lactated Ringer or PBvHb solution (13 g/dl, 1.3 g/kg) during acute hypoxia (FIO2 = 10%, 4 h) or normoxia (FIO2 = 21%) exposure. Our data demonstrated that compared with Ringer-infused animals, in hypoxia and normoxia, PBvHb treatment improved oxygen content but raised mean arterial pressure, lowered stroke volume, heart rate, and cardiac index, which resulted in a net reduction in blood flow and oxygen delivery to the tissues. The PBvHb vasoactive effect was similar in magnitude and direction as to the Ringer-infused animals treated with a nitric oxide synthase inhibitor nitro-l-arginine, suggesting the PBvHb effect is mediated via nitric oxide scavenging. We conclude that infusion of PBvHb is not likely to be useful in treating global hypoxia under these conditions.

Retrospective study to characterize post-obstructive diuresis in cats with urethral obstruction

Urethral obstruction is a common medical emergency in cats. Frequency of post-obstruction diuresis in cats following resolution of urethral obstruction is unknown. The objective of this study was to document frequency and associated clinical features of post-obstruction diuresis in cats. The records of 32 cats undergoing 33 admissions to the Colorado State University Veterinary Hospital for urethral obstruction were reviewed. Signalment, admission blood values, fluid therapy, and urine output were recorded. Diuresis was defined as urine output greater than 2 ml/kg/h. Post-obstructive diuresis occurred in 46% (13/28) of cats within the first 6 h of treatment. Occurrence of post-obstructive diuresis was statistically more likely in cats with venous pH<7.35 on admission. Urine production following resolution of urethral obstruction should be monitored so that fluid therapy can be adjusted to the individual patient, as many cats will have a higher fluid requirement secondary to post-obstruction diuresis.

Pulse oximetry and end tidal carbon dioxide monitoring.

Noninvasive monitoring of cardiopulmonary function through pulse oximetry and capnography provides immediate and important information for the clinician. These monitors are not a replacement for vigilant attention to the patient, however; they should be used in conjunction with arterial blood gas analysis and serial physical examinations to ensure that the continuous readings are accurate and make clinical sense.

Evaluation of trends in marijuana toxicosis in dogs living in a state with legalized medical marijuana: 125 dogs (2005–2010)

OBJECTIVE To report a correlation between the increased number of medical marijuana licenses and marijuana toxicosis in dogs in a state with legalized marijuana for medical use. DESIGN Retrospective case series from January 1, 2005 to October 1, 2010. SETTING Private specialty referral hospital and a university teaching hospital. ANIMALS A total of 125 client-owned dogs presenting for known or suspected marijuana toxicosis with or without a urine drug screening test (UDST). INTERVENTIONS None. MEASUREMENTS AND MAIN RESULTS During the study period, 125 dogs were evaluated including 76 dogs with known marijuana exposure or a positive UDST (group 1), 6 dogs with known marijuana ingestion and a negative UDST (group 2), and 43 dogs with known marijuana ingestion that were not tested (group 3). The incidence of marijuana toxicosis presenting to both hospitals increased 4-fold, while the number of people registered for medical marijuana in the state increased 146-fold in the last 5 years. A significant positive correlation was detected between the increase in known/suspected marijuana toxicosis in dogs (groups 1-3) and the increased number of medical marijuana licenses (correlation R coefficient = 0.959, P = 0.002). Two dogs that ingested butter made with medical grade marijuana in baked products died. CONCLUSIONS A significant correlation was found between the number of medical marijuana licenses and marijuana toxicosis cases seen in 2 veterinary hospitals in Colorado. Ingestion of baked goods made with medical grade tetrahydrocannabinol butter resulted in 2 deaths. UDST may be unreliable for the detection of marijuana toxicosis in dogs.

A technique for central venous pressure measurement in normal horses

OBJECTIVE To investigate a technique of central venous pressure (CVP) measurement using a newly developed catheter in healthy adult horses. DESIGN Prospective experimental study. SETTING University research facility. ANIMALS Twenty healthy adult horses. INTERVENTIONS An equine central venous catheter was inserted into the jugular vein to a length of approximately 80 cm from the mid-cervical region in an attempt to catheterize the pulmonary artery. Pulmonary arterial catheterization was confirmed by echocardiography. Insertion distance and pressure were measured at this location with a disposable manometer. The catheter was then withdrawn until presence in the right atrium was confirmed by echocardiography. Insertion distance and pressure were also measured at this location. The catheter was then withdrawn in 5 cm increments until exiting the jugular insertion site with pressure measured at each location. All pressure measurements were taken with the manometer zero position at the point of the shoulder. MEASUREMENTS AND MAIN RESULTS Pulmonary artery catheterization was successful in 16 of 20 horses. Mean pulmonary arterial pressure was 23.8 cm H2O (17.5 mm Hg) (95% confidence interval [CI] 20.9-26.7 cm H2O [15.4-19.6 mm Hg]). Mean right atrial pressure was 8.3 cm H2O (6.1 mm Hg) (95% CI 7.1-9.4 cm H2O [5.2-6.9 mm Hg]). Right atrial pressure was compared with pressures recorded at sequential insertion distances and resulted in a recommendation for catheter insertion of at least 40 cm for CVP measurement in adult horses. Jugular venous pressure measurement was statistically different from CVP measurement. CONCLUSIONS This catheter measurement technique is well tolerated in normal horses. Routine clinical use of this equine central venous catheter may improve our ability to monitor patients and improve patient care and outcomes of ill horses in hospital.

Hematologic improvement in dogs with parvovirus infection treated with recombinant canine granulocyte-colony stimulating factor.

Previously, dogs with canine parvovirus-induced neutropenia have not responded to treatment with recombinant human granulocyte-colony stimulating factor (rhG-CSF). However, recombinant canine G-CSF (rcG-CSF) has not been previously evaluated for treatment of parvovirus-induced neutropenia in dogs. We assessed the effectiveness of rcG-CSF in dogs with parvovirus-induced neutropenia with a prospective, open-label, nonrandomized clinical trial. Endpoints of our study were time to recovery of WBC and neutrophil counts, and duration of hospitalization. 28 dogs with parvovirus and neutropenia were treated with rcG-CSF and outcomes were compared to those of 34 dogs with parvovirus and neutropenia not treated with rcG-CSF. We found that mean WBC and neutrophil counts were significantly higher (P < 0.05) in the 28 dogs treated with rcG-CSF compared to disease-matched dogs not treated with rcG-CSF. In addition, the mean duration of hospitalization was reduced (P = 0.01) in rcG-CSF treated dogs compared to untreated dogs. However, survival times were decreased in dogs treated with rcG-CSF compared to untreated dogs. These results suggest that treatment with rcG-CSF was effective in stimulating neutrophil recovery and shortening the duration of hospitalization in dogs with parvovirus infection, but indicate the need for additional studies to evaluate overall safety of the treatment.

Successful management of a dog that had severe rhabdomyolysis with myocardial and respiratory failure

CASE DESCRIPTION - A 6-year-old castrated male Llewelyn Setter was evaluated because of an acute onset of myalgia and respiratory distress. CLINICAL FINDINGS - Physical examination revealed a stiff stilted gait, swollen muscles that appeared to cause signs of pain, panting, and ptyalism. The dog had a decrease in palpebral reflexes bilaterally and a decrease in myotatic reflexes in all 4 limbs. The panniculus reflex was considered normal, and all other cranial nerve reflexes were intact. Serum biochemical analysis revealed markedly high cardiac troponin-I concentration and creatine kinase and aspartate aminotransferase activities. Urinalysis revealed myoglobinuria. Results for thoracic and abdominal radiography, blood pressure measurement, and an ECG were within anticipated limits. Echocardiographic findings were consistent with secondary systolic myocardial failure. Arterial blood gas analysis confirmed hypoxemia and hypoventilation. The dog had negative results when tested for infectious diseases. Examination of skeletal muscle biopsy specimens identified necrotizing myopathy. TREATMENT AND OUTCOME - Treatment included ventilatory support; IV administration of an electrolyte solution supplemented with potassium chloride; administration of dantrolene; vasopressor administration; parenteral administration of nutrients; use of multimodal analgesics; administration of clindamycin, furosemide, mannitol, and enrofloxacin; and dietary supplementation with L-carnitine and coenzyme Q(10). Other medical interventions were not required, and the dog made a rapid and complete recovery. CLINICAL RELEVANCE - Necrotizing myopathy resulting in rhabdomyolysis and myoglobinuria can lead to life-threatening physical and biochemical abnormalities. Making a correct diagnosis is essential, and patients require intensive supportive care. The prognosis can be excellent for recovery, provided there is no secondary organ dysfunction.

Gastrointestinal Complications of Critical Illness in Small Animals

The gastrointestinal (GI) tract is one of the shock organs in dogs. GI dysfunction in critically ill veterinary patients manifests in mild problems such as hypomotility, anorexia, and nausea to more serious problems such as intractable vomiting, severe diarrhea, and septicemia. Septicemia is a serious complication of GI dysfunction because intestinal flora gains access to a patients bloodstream, leading to infections in other organ systems and a systemic inflammatory response. The therapy for GI dysfunction is mainly supportive, treating nausea and dehydration although supporting the ailing GI tract with adequate enteral nutrition and, in some cases, dietary supplements and antibiotics.