Correlation between the histopathological diagnosis by AgNOR count and AgNOR area in canine mammary tumors.

BACKGROUND: Mammary tumors are the most common type of tumor in female dogs. The histopathological diagnosis is usually made by a hematoxylin-eosin (HE) staining of the tumor, which then requires a pathologist's judgment for assessment of malignancy. The purpose of this study was to investigate an alternative silver staining of some argyrophilic nucleolar organizer regions (AgNOR) for improving the diagnostic accuracy with mammary tumors. HYPOTHESIS: There is a correlation between the histopathological diagnosis by AgNOR count and AgNOR area in canine mammary tumors. ANIMALS: Seventy-three canine mammary tumors from 33 female dogs. MATERIALS AND METHODS: The AgNOR staining was evaluated retrospectively in 73 canine mammary tumors with a parallel HE staining as a "Gold Standard." Both a quantitative manual counting method and a qualitative computerized morphometric method were tested. RESULT: The result from both methods indicated a clinically relevant difference in the mean values of the AgNOR in the following 4 categories: malignant, benign, hyperplastic, and normal mammary tissue. The counting method was superior, with 89% of the cases given a correct diagnosis of a malignant or a nonmalignant canine mammary tumor. The 2 methods were then compared to test their ability to classify the tumors correctly. Again, the counting method was the most reliable method, with a sensitivity of 80% and a specificity of 76% when the upper 50% of the AgNOR counts were presumed malignant. CONCLUSION AND CLINICAL IMPORTANCE: The results indicated that an AgNOR test could be an aid to pathologists as a prognostic indicator or to assist them in deciding between a benign or a malignant diagnosis in questionable cases.

Veterinary cancer registries in companion animal cancer: a review.

Current and prior veterinary cancer registries are few in number and scattered. Different inclusion criteria, dissimilar collection methods and variable reference population estimation methods pose obstacles in the comparisons between veterinary and human cancer registries. Veterinary cancer registries have yielded information on the risk and incidence of different cancer types in certain breeds and geographical regions, as well as provided information on genetic and environmental risk factors in some cancers. The objective of this article is to review the prior and current veterinary cancer registries, the information they have contributed and to discuss different issues relating to their structure including inclusion criteria, study populations, reference populations utilized in evaluations, recorded variables and the outcome from these.

Study of dog and cat owners' perceptions of medical treatment for cancer.

Between April 10 and June 9, 2000, 91 owners of cats and dogs that were being or had been treated with anticancer chemotherapy were given a questionnaire designed to obtain information about their experiences as a result of the discovery and treatment of the disease, the efficacy and side effects of the treatment and their perceptions of the procedures associated with the administration of the drugs. Nearly all of the owners felt that the treatment was worthwhile. The level of observed side effects was low. Well over half of the owners believed that their animal had lived longer than it would have if it had not been treated and that its general wellbeing had improved. In general, they felt that the treatment had been rewarding and that any adverse side effects had been outweighed by the positive experiences during the treatment; they felt that they had been well informed and that their animals had benefited from the treatment.

Electroencephalography in dogs with epilepsy: similarities between human and canine findings.

OBJECTIVES: To investigate the diagnostic value of electroencephalography (EEG) in dogs with epilepsy, applying human criteria for EEG abnormalities observed with this disorder. MATERIAL AND METHODS: Twenty-six dogs with a clinically established diagnosis of epilepsy were investigated with electroencephalography (EEG) in order to evaluate the diagnostic yield of EEG in canine epilepsy. RESULTS: Of 23 dogs with evaluable EEGs 15 (65%) demonstrated abnormal activity. The most common abnormalities were focal low frequency patterns without spikes (48%), followed by focal epileptiform activity (22%) and generalized epileptiform activity (17%). The distribution between focal and generalized activity were 73% and 27%, respectively. Consistency were demonstrated between the clinical- and the EEG-diagnosis in 13 dogs (87%). A relationship was demonstrated between the number of abnormal EEGs and the proximity of a seizure to the EEG examination. CONCLUSION: A marked consistency was demonstrated between the clinical diagnosis of seizure type and the type of abnormalities observed in the EEG, thus indicating that EEG is a valuable diagnostic aid in confirming the diagnosis of epilepsy in dogs. EEG findings in dogs with epilepsy and humans with this disorder were markedly similar.

M-mode echocardiographic diagnosis of dilated cardiomyopathy in giant breed dogs.

M-mode echocardiograms were recorded from 62 giant breed dogs without historical, clinical, electrocardiographic and roentgenologic signs of heart disease, from six dogs with asymptomatic dilated cardiomyopathy (DCM, NYHA class I), and 13 dogs with symptomatic DCM (NYHA class III-IV). There was a general trend that several echocardiographic parameters were significantly in control Great Danes as compared to Newfoundlands and Irish Wolfhounds. There were substantial differences in left ventricular size both in systole and diastole and in systolic indices of the left ventricle between the control group, the asymptomatic dogs and symptomatic dogs with DCM (P = 0.0001). There was also a significant decreased in the interventricular septum thickness (P = 0.0001) and left ventricular free wall thickness in systole (P = 0.002) and diastole (P = 0.005) between the three groups. Furthermore, the left atrial/aortic ratio was significantly different between the three groups (P = 0.0001). It was concluded that this study established echocardiographic reference values in giant breed dogs which may be useful in the study of heart diseases in giant breed dogs.

Mitral valve prolapse in 3-year-old healthy Cavalier King Charles Spaniels. An echocardiographic study.

Clinical studies have shown that Cavalier King Charles Spaniels (CKCS) have a high prevalence of mitral valvular insufficiency (MVI). Echocardiography has the potential to disclose early valvular changes, and the present prospective study was designed to investigate the occurrence of mitral valve prolapse (MVP) in young CKCS without heart murmurs, and to correlate the degree of MVP with the clinical status of the dogs by including CKCS with MVI as well. The study was based on blinded evaluations of echocardiographic recordings of mitral valves from 34 CKCS and 30 control dogs. Thirteen (87%) of 15 three-year-old CKCS without heart murmurs had MVP (2 total and 11 partial), as compared with 1 (7%) of 15 three-year-old normal Beagle dogs (P < 0.0001), and none of 15 three-year-old normal Medium Size Poodles (P < 0.0001). Of 19 CKCS with MVI, MVP was found in 84% of the entire group and in 100% of dogs with pulmonary congestion or edema. The occurrence of total MVP tended to be higher in the group with MVI (47%, 9/19), when compared with the younger CKCS without heart murmurs (13%, 2/15, P = 0.06). MVP was positively associated with excessive heart rate variability (P = 0.003). The radius of curvature of the anterior mitral valve leaflet in systole was significantly reduced in dogs with MVP when compared with those without (P < 0.0001). In conclusion, this study shows that CKCS at an early age have a high occurrence of MVP. This suggests: 1) A genetic predisposition of CKCS to MVP; and 2) That MVP is a pathogenetic factor in the development of mitral valvular insufficiency. Follow up studies may add further support to these proposals, and clarify whether echocardiography may be an aid in selecting CKCS for future breeding.

Activation of the renin-angiotensin system in dogs with asymptomatic and mildly symptomatic mitral valvular insufficiency.

The renin-angiotensin system has important pathophysiologic implications in the development of congestive heart failure. The activity of the renin-angiotensin system early in the course of heart disease and heart failure in dogs was evaluated by measuring the plasma renin activity (PRA) and plasma aldosterone concentration (PAC) in 18 Cavalier King Charles Spaniels with asymptomatic or mildly symptomatic mitral valvular insufficiency, and in 18 healthy Cavalier King Charles Spaniels. All dogs were unmedicated and had no other diseases. The PRA was high in the dogs with mitral valvular insufficiency (median 3.44 ng/mL/h, interquartile interval 2.59 to 8.66 ng/mL/h) compared with the controls (median 2.51 ng/mL/h, interquartile interval 1.44 to 3.58 ng/mL/h). The PAC was also higher in the dogs with mitral insufficiency (median 53 pg/mL, interquartile interval 33 to 138 pg/mL) than in the control group (median 27 pg/mL, interquartile interval 11.5 to 54 pg/mL). However, there was considerable overlap between the 2 groups in both PRA and PAC. It was concluded from these data that there is early activation of the renin-angiotensin system in some Cavalier King Charles Spaniels with mitral valvular insufficiency. Further prospective studies are needed to determine if early intervention with angiotensin-converting enzyme inhibitors will be valuable in this group of patients.

Activation of the renin-angiotensin system in dogs with asymptomatic and symptomatic dilated cardiomyopathy.

Plasma renin activity (PRA) and plasma aldosterone concentration (PAC) were assessed in 23 dogs, nine of which had asymptomatic dilated cardiomyopathy (DCM) (New York Heart Association [NYHA] class I), eight had symptomatic DCM (NYHA class III) and six had severe congestive heart failure due to DCM (NYHA class IV). None of the dogs had received any drugs before the study. PRA was increased in dogs with DCM (NYHA classes III and IV) (median values 3.8 and 30.8 ng ml-1 hour-1) compared with normal dogs (median 0.89 ng ml-1 hour-1). However, PRA was only marginally increased in dogs with DCM NYHA class I (P = 0.06). The PAC was also increased in dogs with DCM (NYHA classes III and IV) (median values 123 and 600 pg ml-1) compared with normal dogs (median 61 pg ml-1). The PAC was not significantly increased in the early stage of DCM (NYHA class I). It was concluded that in dogs with DCM, the activity of the renin-angiotensin system (RAS) was increased in NYHA functional classes III and IV, and that the increase was correlated with the severity of the disease. The fact that the RAS tended to be activated in dogs with asymptomatic DCM supports the rationale of early therapeutic intervention with inhibitors of the angiotensin-converting enzyme (ACE) as first line therapy in congestive heart failure.

Effects of a low sodium diet with a high potassium content on plasma endothelin-1, atrial natriuretic peptide and arginine vasopressin in normal dogs.

Eight clinically healthy male beagle dogs received a low sodium diet for 5 weeks. Before and after this period the dogs received a control diet for 3 weeks. Both diets provided the dogs with approximately 6.8 mmol K+/kg/day. Neither introducing nor withdrawing the low sodium diet changed the plasma concentrations of endothelin-1 (ET-1), atrial natriuretic peptide (ANP) and arginine vasopressin (AVP). Pooled data from the control periods were not different from the low sodium period for either ET-1 (2.31 pg/ml and 2.09 pg/ml, P = 0.21), ANP (42.51 pg/ml and 38.99 pg/ml, P = 0.44) or AVP (4.14 pg/ml and 4.16 pg/ml, P = 0.91). It was concluded that ET-1, ANP and AVP in normal dogs are unaffected by a 6-fold change in sodium intake in the presence of a high potassium intake.

Short term effects of acute inhibition of the angiotensin-converting enzyme on the renin-angiotensin system and plasma atrial natriuretic peptide in healthy dogs fed a low-sodium diet versus a normal-sodium diet.

The purpose of the present study was to quantify some of the short term responses of the renin-angiotensin system (RAS) to a recommended dosage of the angiotensin-converting enzyme inhibitor enalapril in clinically healthy dogs fed a normal-sodium and a low-sodium diet. A single dose of enalapril (0.5 mg/kg PO) was given to eight clinically healthy male Beagle dogs after a period where the dogs were fed a normal-sodium diet and low-sodium diet, respectively. Serum angiotensin-converting enzyme activity (ACE), plasma renin activity (PRA), plasma aldosterone concentration (PAC), and plasma atrial natriuretic peptide (ANP) concentration were measured during the following twenty-four hour period. The data indicate that enalapril induced a potent blockade of the renin-angiotensin system (RAS) for at least twenty-four hour. Specifically, enalapril during low-sodium diet elicited an exaggerated increase in PRA and a diminished decrease in ACE and ANP when compared to the results of the drug during normal-sodium diet. Long term controlled studies of enalapril in dogs with congestive heart failure (CHF) are warranted in order to determine the duration of action and optimal dose of enalapril.

Some effects of a low sodium diet high in potassium on the renin-angiotensin system and plasma electrolyte concentrations in normal dogs.

Eight normal male Beagle dogs received 0.7 mmol Na+/kg/day for 5 weeks and 4.0 mmol Na+/kg/day in one 3 week control period preceding and another similar period following the low sodium period. The dogs received 6.8 mmol K+/kg/day throughout the study. The median plasma renin activity (PRA) and plasma aldosterone concentration (PAC) were higher in the low sodium period than in the following control period (0.67 versus 0.28 ng/ml/h, p < 0.0001) and (204 versus 31 pg/ml, p < 0.0001). PRA and PAC quickly stabilized on a new steady level in response to altered intake of sodium chloride. The angiotensin-converting enzyme (ACE) activity was not changed by the altered intake of sodium chloride. The plasma concentrations of sodium and chloride were increased during the low sodium period. This could be due to an indirect effect of the high potassium intake of the dogs. Potassium leads to an increased secretion of aldosterone and thereby to an increased retention of sodium and chloride in the kidney. The possible implications of a high potassium content in a low sodium diet are discussed.

Applicability of the critical difference.

The present study is concerned with the critical difference, which may help to judge whether or not the difference between two consecutive measurements with a certain probability (i.e. 95 percent) may be ascribed to natural variation. Knowledge of the applicability of the critical difference in veterinary medicine is sparse and therefore, to justify future use of the critical difference, it is important to know whether or not the critical difference performs as expected. The hypothesis to be tested in this study was that at least 95 percent of the differences between consecutive measurements, that have been obtained in animals where the component measured is known to be unchanged, should be within the critical difference. From previous studies it was known that a low-sodium diet had no influence on the plasma potassium concentration. The critical difference of the plasma potassium concentration in dogs was calculated as 0.5 mmol/l. using weekly measurements of this plasma component in a group of twenty healthy dogs. To test the hypothesis, this value was compared to the differences between consecutive weekly measurements of this plasma component in another group of eight dogs fed a low-sodium diet for five weeks. In agreement with previous studies, the plasma potassium concentration in the eight dogs did not change significantly during the feeding experiment. Of the fourty differences between consecutive weekly measurements, thirty-six were within the critical difference. This number was not different from the number expected from the hypothesis and thus, the critical difference performed as expected.(ABSTRACT TRUNCATED AT 250 WORDS)

Congenital myasthenic syndrome in the dog breed Gammel Dansk Hønsehund: clinical, electrophysiological, pharmacological and immunological comparison with acquired myasthenia gravis.

The effect of anticholinesterase drugs on the clinical and electrophysiological features in a canine congenital myasthenic syndrome is compared with findings in acquired myasthenia gravis in dogs. Anticholinesterase treatment had no effect on muscle weakness or electrophysiological parameters in the congenital myasthenic syndrome in contrast to its effect on clinical signs and electrophysiological parameters in acquired myasthenia gravis. The lack of effect of anticholinesterase in congenital myasthenia suggests a presynaptic defect as the aetiological factor. No antibodies to acetylcholine receptors were found in the Danish dog breed Gammel Dansk Hønsehund with the myasthenic syndrome. This classifies the disease in the group of canine and human congenital myasthenic diseases.

Pharmacokinetics and pharmacodynamics of guanidine hydrochloride in an hereditary myasthenia gravis-like disorder in dogs.

The pharmacokinetic parameters of guanidine hydrochloride were analysed in dogs with an hereditary neuromuscular transmission disorder by the use of 14C-guanidine hydrochloride. The content of intravenously administrated 14C-guanidine hydrochloride in plasma, urine and faeces was determined by liquid scintillation counting. The drug was rapidly distributed in the organism with a plasma half-life of 7-8 h and most was eliminated in the urine. The clinical and electrophysiological effects of guanidine hydrochloride on the muscular weakness and fatigue induced by exercise were determined after oral and intravenous administration. Guanidine hydrochloride improved muscle-function, but had no apparent effect when administered during an attack of weakness. An effective level of guanidine in plasma (2-10 micrograms/ml) changed the muscle response evoked by trains of repetitive stimulation. The myasthenic decrement during short stimulation trains was unchanged.

Prostaglandin F2 alpha treatment of feline open pyometra.

Pyometra is not a very common problem in feline practice. When it occurs it often results in sterility in spite of proper medical treatment. Prostaglandins have been used in the treatment of reproductive abnormalities including pyometra in different animal species (Boothe 1984). Therefore it was taken in as a treatment of the pyometra in five breeding cats, where ovariohysterectomy was undesirable.

A hereditary neuromuscular disorder in dogs.

A disorder characterized by reduced tolerance to exercise has been observed in the breed "Gammel Dansk Honsehund." Results of genealogical studies and test matings suggest an autosomal recessive mode of inheritance. Eighteen interrelated dogs were examined electrophysiologically. Recording of electrical and mechanical responses at low rates of nerve stimulation revealed a normal positive staircase phenomenon. At fast rates of stimulation for 5 minutes there was a facilitation of the electrical and mechanical responses during the first minute, followed by a gradual decrease of both responses in affected dogs but not in controls. After induced fatigue, stimulation at 3 Hz/3 seconds revealed an average decrement of 22%, which resolved within 3 to 4 minutes. Only guanidine had a favorable clinical effect and reduced or normalized the early facilitation. Examination of dog serum against human acetylcholine-receptor antigen showed negative titers. It is most likely that the disorder described here is similar to the congenital human type of myasthenia gravis.