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Biomedical subjects

L M Howe

Publications and source records attributed to L M Howe.

16 recordsLinked to original sources
PubMed2002

Repeatability and prediction from a telephone questionnaire measuring diet and activity level in cats.

A telephone questionnaire was developed to collect information on diet, activity level, and health as part of a prior study examining long-term outcome of early-age vs. traditional-age gonadectomy in cats. The objectives of our current study were to measure the repeatability of the questionnaire through time, to describe changes in diet and activity level over a period of 1-2 years, and to determine whether current diet and activity level characteristics might influence owner ability to recall past information.A total of 100 previously interviewed cat owners completed the second administration of the telephone questionnaire. The interval between the first and second administration of the questionnaire ranged from 0.5 to 2.6 years (median=1.5 years). Owners answered multiple-choice questions related to activity level, appetite, body condition, diet type and brand (open-ended), frequency of feeding, indoor/outdoor status, and time spent outdoors. All variables measured in the questionnaire were analyzed using kappa and a 95% confidence interval. Agreement between the original and current interviews was poor for questions referring to activity level, appetite, body condition, type and brand of treats fed, and table scraps. Agreement was moderate for questions referring to brand of dry and canned foods fed, frequency of feeding, and time spent outdoors. Agreement was high for questions referring to whether dry and canned foods were fed and indoor/outdoor status. Change over time as assessed by kappa was moderate-to-high for all variables measured with the exception of whether dry diet was fed and indoor/outdoor status. Recall of all variables that changed appeared to be at least moderately influenced by current characteristics.

Age Factors↗
PubMed2001

Long-term outcome of gonadectomy performed at an early age or traditional age in dogs.

OBJECTIVE: To determine long-term results and complications of gonadectomy performed at an early age (prepubertal) or at the traditional age in dogs. DESIGN: Cohort study. ANIMALS: 269 dogs from animal shelters. PROCEDURE: Dogs that underwent gonadectomy were allotted to 2 groups on the basis of estimated age at surgery (traditional age, > or =24 weeks old; prepubertal, < 24 weeks old). Adoptive owner information was obtained from shelter records, and telephone interviews were conducted with owners to determine physical or behavioral problems observed in the dogs since adoption. Follow-up information was obtained from attending veterinarians for dogs with complex problems or when owners were uncertain regarding the exact nature of their dog's problem. RESULTS: Prepubertal gonadectomy did not result in an increased incidence of behavioral problems or problems associated with any body system, compared with traditional-age gonadectomy, during a median follow-up period of 48 months after gonadectomy. Rate of retention in the original adoptive household was the same for dogs that underwent prepubertal gonadectomy as those that underwent traditional-age gonadectomy. Infectious diseases, however, were more common in dogs that underwent prepubertal gonadectomy. CONCLUSIONS AND CLINICAL IMPLICATIONS: With the exception of infectious diseases, prepubertal gonadectomy may be safely performed in dogs without concern for increased incidence of physical or behavioral problems during at least a 4-year period after gonadectomy.

Age Factors↗
PubMed2001

Potential for cloning dogs.

The aim of this study was to determine whether nuclear transplantation could be used to clone a dog using donor nucleus cells collected from an adult female. Fibroblasts obtained from skin biopsies were fused with enucleated bovine or canine oocytes. The resulting cloned embryos were cultured in vitro to monitor embryonic development. A proportion of the resulting embryos was transferred into surrogate bitches for development to term. When canine oocytes were used as recipient ova for canine fibroblasts, 23% of the resulting embryos cleaved at least once after culture in vitro. Five cloned embryos were transferred into three synchronized recipient bitches, but no pregnancies resulted. When bovine oocytes were used as recipinets for canine fibroblasts, 38% cleaved to the two- to four-cell stage and 43% cleaved to the eight- to 16-cell stage. Forty-seven of these embryos were transferred into four recipient females, resulting in a single conceptus that ceased development at about day 20 of gestation. The desire for cloned dogs is considerable and will undoubtedly incite the development of successful methods for cloning companion animals. However, significant investment into additional research is required, especially in the areas of in vitro maturation of oocytes and control of the oestrous cycle of bitches.

Animals↗
PubMed2000

Long-term outcome of gonadectomy performed at an early age or traditional age in cats.

OBJECTIVE: To determine long-term results and complications of gonadectomy performed at an early age (prepubertal) or at the traditional age in cats. DESIGN: Cohort study. ANIMALS: 263 cats from animal shelters. PROCEDURE: Cats that underwent gonadectomy were allotted to 2 groups on the basis of estimated age at surgery (traditional age, > or = 24 weeks old; prepubertal, < 24 weeks old). Adoptive owner information was obtained from shelter records, and telephone interviews were conducted with owners to determine physical or behavioral problems observed in the cats after adoption. Follow-up information was obtained from attending veterinarians for cats with complex problems or when owners were uncertain regarding the exact nature of their cat's problem. RESULTS: Compared with traditional-age gonadectomy, prepubertal gonadectomy did not result in an increased incidence of infectious disease, behavioral problems, or problems associated with any body system during a median follow-up period of 37 months. Additionally, the rate of retention in the original adoptive household was the same for cats that underwent prepubertal gonadectomy as those that underwent traditional-age gonadectomy. CONCLUSIONS AND CLINICAL RELEVANCE: Prepubertal gonadectomy may be performed safely in cats without concern for increased incidence of physical or behavioral problems for at least a 3-year period after gonadectomy.

Adoption↗
PubMed2000

Novel agents in the therapy of endotoxic shock.

Endotoxic shock, or Gram-negative septic shock, can occur as a component of Gram-negative sepsis and is characterised by hypotension, poor tissue perfusion and multi-organ dysfunction. Despite antibiotic therapy and intensive care management, the morbidity and mortality rates of Gram-negative septic shock remain high. Endotoxin mediates its effects through interaction with receptors on the surface of a variety of host cells. These interactions result in the production and release of numerous biochemical mediators including nitric oxide, cytokines, prostaglandins and leukotrienes and toxic oxygen radicals. It is these biochemical mediators that exert toxic effects during endotoxic shock and which are often the target of novel treatment strategies. Several of these pharmacological agents are currently being investigated for use in Gram-negative septic shock and include inhibitors of the enzyme responsible for nitric oxide production, scavengers of the nitric oxide molecule and cytokine modulators. Although many agents have been studied for potential use as modulators of cytokine levels, this study will focus on pentoxifylline and the 21-aminosteroids, or lazaroids. Examination of the literature regarding pharmacological agents used to treat endotoxic shock often yields confusing and contradictory results. The reasons for these mixed results include differences in models, drug dosages, dosing methods and intervals and timing of administration relative to disease duration and severity. However, despite mixed results, several of the drugs discussed in this paper offer promise in the therapy of an often frustrating and lethal condition.

Animals↗
PubMed2000

Nitric oxide generation in a rat model of acute portal hypertension.

OBJECTIVE: To document blood nitric oxide concentrations in the portal vein and systemic circulation in a rat model of acute portal hypertension and compare values with a control group and a sham surgical group. ANIMALS: 30 rats; 10 controls (group 1), 10 sham surgical (group 2), and 10 rats with surgically induced acute portal hypertension (group 3). PROCEDURE: Following induction of anesthesia, catheters were placed surgically in the carotid artery, jugular, and portal veins of group 2 and 3 rats and in the carotid artery and jugular vein of group 1 rats. Baseline heart and respiratory rates, rectal temperature, and vascular pressure measurements were obtained, and blood was drawn from all catheters for baseline nitric oxide (NO) concentrations. Acute portal hypertension was induced in the group 3 rats by tying a partially occluding suture around the portal vein and a 22-gauge catheter. The catheter was then removed, resulting in a repeatable degree of portal vein impingement. After catheter placement, all variables were remeasured at 15-minute intervals for 3 hours. RESULTS: Blood nitric oxide concentrations were greater in all vessels tested in group 3 than in group 2 rats. CONCLUSIONS AND CLINICAL RELEVANCE: Acute portal hypertension in this experimental model results in increased concentrations of NO in the systemic and portal circulation. On the basis of information in the rat, it is possible that increased NO concentrations may develop in dogs following surgical treatment of congenital portosystemic shunts if acute life-threatening portal hypertension develops. Increased NO concentrations may contribute to the shock syndrome that develops in these dogs.

Animals↗
PubMed1999

Detection of portal and systemic bacteremia in dogs with severe induced hepatic disease and multiple portosystemic shunts.

OBJECTIVE: To determine existence of portal and systemic bacteremia in dogs with induced severe hepatic disease, compared with clinically normal dogs, before and after vena caval banding. ANIMALS: 6 control dogs and 10 dogs with induced severe hepatic disease and multiple portosystemic shunts (PSS). PROCEDURE: Dogs of the diseased group were given dimethylnitrosamine (2 mg/kg of body weight, PO) twice weekly until multiple PSS developed. Surgery was performed on dogs of both groups, and blood for baseline aerobic and anaerobic bacterial culture was collected from catheters placed in the portal and hepatic veins and caudal vena cava. All dogs underwent vena caval banding, and blood for aerobic and anaerobic bacterial culture was collected from the portal and hepatic venous catheters at 120, 240, and 360 minutes after banding. RESULTS: Compared with control dogs (16% gram-positive and 84% gram-negative bacteria), diseased dogs had significantly higher percentage of gram-positive bacteria (42% of positive culture results, P < or = 0.01) and significantly lower percentage of gram-negative bacteria (58% of positive culture results, P < or = 0.01) isolated. Pseudomonas aeruginosa was isolated most frequently from dogs of both groups; more than 1 organism was isolated from 5 dogs of each group. Antimicrobial susceptibility included that to aminoglycosides (particularly amikacin), fluorinated quinolones, and imipenem. CONCLUSION: Portal and systemic, predominantly gram-negative, bacteremia is present in catheterized, clinically normal dogs and dogs with dimethylnitrosamine-induced hepatic disease and multiple PSS.

Amikacin↗
PubMed1998

Treatment of endotoxic shock: glucocorticoids, lazaroids, nonsteroidals, others.

Review of the literature would indicate that a therapy inhibiting a single step in the inflammatory mediator cascade, although potentially beneficial, cannot serve as the "magic bullet" in endotoxic shock. Thus, combination therapy using drugs that target multiple steps in the mediator cascade may prove useful in the future. Until controlled clinical studies have been performed in veterinary medicine using the agents discussed in this manuscript (or others), many questions will remain regarding the best possible pharmacologic therapies to use in supplementing traditional supportive care (e.g., fluids, broad-spectrum antimicrobials) measures. Many of the therapies discussed in this manuscript hold tremendous potential, but must be administered before endotoxic shock occurs or early in the course of endotoxic shock to elicit a beneficial response. Unfortunately this is not usually possible in the clinical situation. Further, the possibility of eliciting a detrimental response by use of drugs at inappropriate dosages or too late in the course of the disease must be considered. In time, therapies may be grouped into those that hold promise for being beneficial in the patient at risk for endotoxic shock and those that are beneficial for treatment of established endotoxic shock. Therapies that may hold promise for the patient with established endotoxic shock possibly include the lazaroids, certain NSAIDs, pentoxifylline, and selective inhibitors of iNOS activity. Although still controversial, methylprednisolone and other glucocorticoids are probably best reserved for the patient at risk for endotoxic shock, or those identified very early in the course of endotoxemia and endotoxic shock, and should never be used in conjunction with NSAIDs. Since no one therapy is likely to provide the "magic bullet" for the patient in endotoxic shock, treatment may ultimately involve combination therapy using some of these drugs that target different pathways and mediators and may also include antibodies against endotoxin or its mediators.

Animals↗
PubMed1997

Short-term results and complications of prepubertal gonadectomy in cats and dogs.

OBJECTIVE: To determine short-term results and complications of prepubertal gonadectomy in cats and dogs. DESIGN: Prospective randomized study. ANIMALS: 775 cats and 1,213 dogs. PROCEDURE: Animals undergoing gonadectomy were allotted into 3 groups on the basis of estimated age (group 1, < 12 weeks old; group 2, 12 to 23 weeks old; group 3, > or = 24 weeks old). Complications during anesthesia, surgery, and the immediate postoperative period (7 days) were recorded. Complications were classified as major (required treatment and resulted in an increase in morbidity or mortality) or minor (required little or no treatment and caused a minimal increase in morbidity). An ANOVA was used to detect differences among groups in age, weight, body temperature, and duration of surgery. To detect differences in complication rates among groups, chi 2 analysis was used. RESULTS: Group 1 consisted of 723 animals, group 2 consisted of 532, and group 3 consisted of 733. Group-3 animals had a significantly higher overall complication rate (10.8%) than group-1 animals (6.5%), but did not differ from group-2 animals (8.8%). Differences were not detected among the 3 groups regarding major complications (2.9, 3.2, and 3.0% for groups 1, 2, and 3, respectively), but group-3 animals had significantly more minor complications (7.8%) than group-1 animals (3.6%), but not group-2 animals (5.6%). CLINICAL IMPLICATIONS: In this study, prepubertal gonadectomy did not increase morbidity or mortality on a short-term basis, compared with gonadectomy performed on animals at the traditional age. These procedures may be performed safely in prepubertal animals, provided that appropriate attention is given to anesthetic and surgical techniques.

Age Factors↗
PubMed1997

Endotoxemia associated with experimentally induced multiple portosystemic shunts in dogs.

OBJECTIVE: To document presence of endotoxin in portal and systemic blood in a model of canine multiple portosystemic shunts (PSS), and compare values in clinically normal dogs, before and after vena caval banding. ANIMALS: 6 control dogs and 10 dogs with dimethylnitrosamine-induced multiple PSS that were subjected to vena caval banding. PROCEDURE: Dimethylnitrosamine was administered orally (2 mg/kg of body weight, twice weekly) to the 10 dogs in the diseased group until multiple PSS developed. Surgery was then performed on all 16 dogs (both groups), and shunts were confirmed in the diseased dogs. Blood was collected from the portal vein, hepatic vein, and caudal vena cava baseline endotoxin determination and aerobic and anaerobic blood culturing. Baseline pressure measurements were taken from the portal venous catheter; then vena caval banding was performed. Blood for endotoxin determinations was taken from all vessels 20, 40, 60, 120, 240, and 360 minutes after banding; portal pressure measurements were taken at the same time as sample acquisition. Blood for culturing was taken from the portal and hepatic venous catheters at 120, 240, and 360 minutes after banding. RESULTS: Dogs in the diseased group had significantly greater overall presence of endotoxin in the portal vein (P < or = 0.0002), hepatic vein (P < or = 0.0001), and caudal vena cava (P < or = 0.0004) than did control dogs. With respect to time, endotoxin presence was greater in the diseased group before banding (P < or = 0.0002), and at 20 (P < or = 0.0008), 40 (P < or = 0.002), 60 (P < or = 0.006), and 120 (P < or = 0.01) minutes after banding. CONCLUSIONS: Endotoxemia is more frequently present in catheterized dogs with dimethylnitrosamine-induced hepatic disease and multiple PSS, compared with clinically normal dogs. Additionally, portal pressure changes induced by vena caval banding did not affect endotoxemia. CLINICAL RELEVANCE: Endotoxemia may exist in dogs with hepatic disease and multiple PSS, and should be kept in mind when formulating treatment (particularly antimicrobial selection) for dogs with suspected endotoxemia.

Animals↗
PubMed1996

Multiple extrahepatic portosystemic shunts in dogs: 30 cases (1981-1993).

OBJECTIVE: To describe the long-term outcome in dogs with naturally developing multiple extrahepatic portosystemic shunts (PSS). DESIGN: Retrospective case series. ANIMALS: 30 dogs with multiple PSS. PROCEDURE: Medical records of dogs with multiple PSS were reviewed. Follow-up data were obtained by 1 or more of the following methods: recheck at the veterinary teaching hospital (n = 6) or telephone contact with the referring veterinarian (n = 18) or owner (n = 10). The chi 2 or Mann-Whitney rank sum test was used to determine the association of clinical factors with long-term outcome. Survival curves were generated by the Kaplan-Meier product limit method. RESULTS: Median age at diagnosis was 1 year. Findings on exploratory surgery in 25 dogs included ascites; numerous tortuous vessels connecting the portal vein with systemic veins; a small, misshapen liver; and an enlarged portal vein. The most common lesions on histologic evaluation of hepatic tissue specimens were hepatocellular atrophy, portal vascular duplication, cirrhosis, inflammation, and bile duct proliferation. Twelve dogs were treated surgically with vena caval banding, whereas 13 dogs were treated conservatively with dietary restriction of protein and administration of antibiotics, diuretics, and other drugs. Long-term survival and quality of life were similar in dogs from both treatment groups. Median follow-up interval in dogs that survived hospitalization was 24 months (range, 1 to 54 months). CLINICAL IMPLICATIONS: On the basis of these findings, vena caval banding in dogs with multiple PSS is not superior to medical and nutritional treatment.

Animals↗
PubMedDate not supplied

Nitric oxide: a review for veterinary surgeons.

Nitric oxide (NO) is an endogenous gas that serves as a biologic messenger in many physiologic processes including neurotransmission, blood-pressure control, the immune system's ability to kill tumor cells, and wound healing. NO is produced after oxidation of L-arginine by a family of nitric oxide synthase (NOS) enzymes. Two of the NOS enzymes are present continuously and are thereby termed constitutive NOS. One of the enzymes, inducible NOS, is not typically expressed in resting cells and is induced by various substances including endotoxin, some cytokines, and microbial products. Thus, NO often has paradoxical activities. When NO is over- or underproduced, it can result in potentiation of disease states with disastrous results. This review discusses the biochemistry of NO, its functions in normal and disease states, and therapy for modulating NO production in disease states.

Animal Diseases↗
PubMedDate not supplied

A canine model of multiple portosystemic shunting.

The objective of this study was to develop and describe an experimental canine model of multiple acquired portosystemic shunts (PSS) similar in nature to spontaneously occurring PSS. Sixteen dogs were used and were divided into a control (n = 6) and a diseased group (n = 10). Dogs of the diseased group were administered dimethylnitrosamine (2 mg/kg of body weight, po) twice weekly, and clinicopathologic, ultrasonographic, and hepatic scintigraphic findings were recorded during the development of hepatic disease and PSS. Surgery was then performed to permit visual verification of multiple shunts, catheter placement for portography examination, and biopsy of the liver. All diseased dogs developed severe hepatic disease and multiple PSS as documented visually at surgery and on portography. Based on this study, dimethylnitrosamine-induced portosystemic shunting appears to be an appropriate model for spontaneously occurring multiple PSS secondary to portal hypertension.

Animals↗
PubMedDate not supplied

Inadvertent prostatectomy as a complication of cryptorchidectomy in four dogs.

Inadvertent prostatectomy was identified as a complication of cryptorchidectomy in four dogs. Surgical correction of the resulting urethral trauma was attempted in each case. One case was euthanized due to a poor prognosis for recovery. Three cases survived without clinical evidence of urinary incontinence. Inadvertent prostatectomy during cryptorchidectomy may be avoided by adequate surgical exposure and proper identification of the abdominally retained testicle.

Animals↗