Dominating north american forest pathology issues of the 20th century

ABSTRACT The profession of forest pathology evolved in the early decades of the 20th century from a science describing microorganisms that infect trees to a discipline that was required to deal with numerous disease outbreaks. The foundations of the science were carried from Europe to the "New World" and initially dealt with decay and the resource losses it caused. The profession was forced to shift direction quickly because it was called upon to address major diseases caused by the introduction of pathogens from other continents; notably organisms inciting chestnut blight, Dutch elm disease, and white pine blister rust. Changes in natural ecosystems that resulted from a legacy of poor forest practice, land abuse, and an increase in plantation monocultures gave rise to other disease problems when host-pathogen balances in natural ecosystems were disturbed. Further, the need for large numbers of tree seedlings resulted in numerous nursery disease problems. Although many of the principles of general plant pathology had application to the study of forest diseases, the long-term nature of forests requires varied approaches to their study and management. Today, the science continues to evolve as the complexities of forest ecosystems unfold.     

The development and validation of a geographic information system database for the poultry industry on the Delmarva Peninsula

A geographic information system (GIS) database of the poultry industry on the Delmarva Peninsula was developed through a cooperative agreement between the Delmarva Poultry Industry, Inc., and the Virginia-Maryland Regional College of Veterinary Medicine. The purpose of this database was to facilitate disease surveillance and assist in managing the response to outbreaks and other emergencies. Two methods of data collection were employed and are described in this paper. The first method was to visit each poultry farm and collect the latitude and longitude coordinates with a handheld global positioning system unit. The second method used property ownership information, aerial photographs, and a GIS to determine the latitude and longitude of each poultry farm. There was no significant difference between the two methods in the accuracy of the results, but there was a large difference in the amount of time and money necessary to obtain the data. These findings indicate that whereas there are many ways to obtain accurate data for a GIS database, other factors may influence which method is chosen. A subset of farms contained within the database was visited to assess the accuracy of the locations contained within the database. Of the 240 farms visited for validation, 212 showed evidence of a functioning or previously functioning poultry operation. The corresponding error rate was 11%. This demonstrates the need to assure that the database is kept up to date to ensure that attrition among poultry growers is recorded. Several potential factors that might contribute to sources of error are discussed.     

Trends in cellulitis condemnations in the Ontario chicken industry between April 1998 and April 2001

We conducted a retrospective study to determine the prevalence of cellulitis condemnations in the Ontario chicken industry and the relative proportion of variation attributable to factors that vary between processors, producers, and lots and over time. The time span studied was April 1998 to April 2001. We obtained condemnation data randomly from the Chicken Farmers of Ontario and analyzed the data with a generalized mixed model. The (weighted) average prevalence of cellulitis in Ontario between April 1998 and 2001 was 0.94% (0.87%, 1.03%). The prevalence of cellulitis ranged from 0% to 14.9%, with one outlier at 30% and 95% of the data between 0 and 2.58%. The final mixed model we used to describe the variation in the prevalence of cellulitis between lots included random effect terms, the plant where the birds were processed, the producer, the quota period when the birds were processed, and the interaction term quota period by processing plant, as well as fixed effects terms, the type of inspection system and the average weight of the birds. The final model containing these variables explained approximately 78% of the total variation in the data. Our findings indicate all three random effects variables accounted for a significant amount of variation in the cellulitis data; however, the greatest source of variation was ascribed to the plants where the birds were processed. Some of the variation in cellulitis associated with processing plants was explained by the type of inspection system used by the plant, but even after controlling for this factor, there remained a relatively large amount of variation between processing plants (approximately 30%). These findings suggest there may be discrepancies in the diagnoses of the condition. Some of the variation in the prevalence of cellulitis (approximately 13%) was also attributed to the producer; however, more of the variation in the data was attributed to differences in lot-specific factors (approximately 22%). Therefore, future control efforts for cellulitis should focus on standardizing the classification of cellulitis at processing plants and identifying lot specific factors that may increase the risk of the condition.     

Acute severe hemorrhage secondary to arterial invasion in a dog with thyroid carcinoma

A 7-year-old spayed female Labrador Retriever was referred because of progressive swelling and bruising of the neck, hemothorax, a possible mediastinal mass, and stridor. At the time of admission, the dog was recumbent, mentally dull, tachycardic, and hypothermic. Fluid therapy with hydroxyethyl starch and a balanced electrolyte solution was administered because of presumed hypovolemic shock secondary to hemorrhage; multiple units of packed RBCs and fresh frozen plasma were also administered. On the basis of the computed tomographic images, extensive subcutaneous, subfascial, and cranial mediastinal hemorrhage; hemothorax; prescapular lymphadenopathy; and a contrast-enhancing mass in the left cranioventral aspect of the neck were diagnosed. Exploratory surgery of the neck was performed. All subcutaneous structures were encased in a large blood clot. During dissection of the clot, pulsatile bleeding was observed just caudal to and to the left of the larynx; ligation of the left common carotid artery resulted in immediate cessation of the pulsatile bleeding. Further surgical exploration revealed a 2.5 x 2.5-cm mass adhered to the left common carotid artery at the level of the branching to the left cranial thyroid artery. The mass was removed; the histologic diagnosis was thyroid carcinoma. Three weeks after surgery, treatment with a combination of radiation and chemotherapy (doxorubicin and carboplatin) was begun. Thirteen months after surgery, the dog continued to be free from clinical signs of disease.     

Spontaneous resolution of an isolated ventricular septal defect in a dog

A 5-month-old Maltese was examined because of a holosystolic heart murmur. Results of echocardiography were suggestive of a small isolated interventricular septal defect. Color flow and pulsed-wave spectral Doppler echocardiography confirmed that there was left-to-right blood flow through the defect during systole and diastole. Because of the small size of the defect, the large systolic pressure differential between the ventricles (72.6 mm Hg), and the lack of clinical signs, the small amount of left-to-right shunting was considered clinically unimportant, and no medication or treatment was recommended. Seven months later, the dog was re-examined, and trans-septal blood flow was no longer seen. Isolated interventricular septal defects are a common congenital heart disorder in some breeds of dogs. Such defects may be subclinical in some dogs. In others, they cause a wide spectrum of clinical problems. Findings in this dog suggest that interventricular septal defects may close spontaneously in some dogs.     

Traumatic diaphragmatic hernia in cats: 34 cases (1991-2001)

OBJECTIVE: To determine whether signalment, duration of hernia, clinical signs, contents of hernia, CBC and serum biochemical abnormalities, concurrent injuries, perioperative treatment and administration of analgesics, results of intraoperative anesthetic monitoring data, or level of training of the veterinarian performing the herniorrhaphy was associated with mortality rate after surgical repair of traumatic diaphragmatic hernia in cats. DESIGN: Retrospective study. ANIMALS: 34 cats. PROCEDURE: Review of medical records and a telephone follow-up with owners and referring veterinarians were performed. RESULTS: Mean age of affected cats was 3.6 years; cats that survived to the time of discharge were significantly younger than cats that died or were euthanatized. Tachypnee was the most common clinical sign at hospital admission; cats that survived to the time of discharge had significantly higher respiratory rates than cats that died or were euthanatized after surgery. Postoperative complications developed in 50% of cats; tachypnea and dyspnea were most common. Mortality rate was not associated with duration of hernia or results of preoperative CBC and serum biochemical analyses, but was significantly associated with concurrent injuries. Mortality rate was not associated with hernia contents, intraoperative use of positive inotropes or corticosteroids, episodes of hypotension or severe hypoxia during anesthesia, or level of training of the veterinarian performing the surgery. CONCLUSIONS AND CLINICAL RELEVANCE: Cats that are older or have low to mildly increased respiratory rates and concurrent injuries are more likely to die after surgical repair of traumatic diaphragmatic hernia.     

Evaluation of cardiac function in active and hibernating grizzly bears

OBJECTIVE: To evaluate cardiac function parameters in a group of active and hibernating grizzly bears. DESIGN: Prospective study. ANIMALS: 6 subadult grizzly bears. PROCEDURE: Indirect blood pressure, a 12-lead ECG, and a routine echocardiogram were obtained in each bear during the summer active phase and during hibernation. RESULTS: All measurements of myocardial contractility were significantly lower in all bears during hibernation, compared with the active period. Mean rate of circumferential left ventricular shortening, percentage fractional shortening, and percentage left ventricular ejection fraction were significantly lower in bears during hibernation, compared with the active period. Certain indices of diastolic function appeared to indicate enhanced ventricular compliance during the hibernation period. Mean mitral inflow ratio and isovolumic relaxation time were greater during hibernation. Heart rate was significantly lower for hibernating bears, and mean cardiac index was lower but not significantly different from cardiac index during the active phase. Contrary to results obtained in hibernating rodent species, cardiac index was not significantly correlated with heart rate. CONCLUSIONS AND CLINICAL RELEVANCE: Cardiac function parameters in hibernating bears are opposite to the chronic bradycardic effects detected in nonhibernating species, likely because of intrinsic cardiac muscle adaptations during hibernation. Understanding mechanisms and responses of the myocardium during hibernation could yield insight into mechanisms of cardiac function regulation in various disease states in nonhibernating species.