Biomedical subjects
Publications and source records attributed to M P Littman.
Hematuria leading to life-threatening anemia was evaluated in a 9-year-old male dog. At surgery, an abnormal vessel resembling an ulcerated varicose vein was found on the surface of the bladder mucosa. After removal of the lesion, hematuria ceased and had not recurred 22 months later.
Severe hypertension was diagnosed in a dog that initially was referred for evaluation of visual deficits and retinal hemorrhage and eventually was donated for medical treatment of hypertension. Initial blood pressure measured by direct methods was markedly high (systolic, 275 mm of Hg; diastolic, 170 mm of Hg). Measures of renal function were within normal limits, with the exception of hypotonic urine. A test protocol was designed to exclude possible secondary causes of hypertension; negative results of such tests allowed the diagnosis of essential hypertension. The consistency of the hypertension and its response to medical control were studied for 5 years. Blood pressure while the dog was untreated during those years was 240 +/- 24 mm of Hg (systolic) and 146 +/- 14 mm of Hg (diastolic). Plasma renin activity was within normal limits, and the response of the renin-angiotensin system to varied salt intake was normal. The most effective medications used to lower blood pressure were propranolol and captopril, both of which were more effective than salt restriction alone. Five years after the diagnosis of hypertension, the dog was euthanatized because of chronic renal failure secondary to pyelonephritis. Hypertension was less severe as the condition progressed into chronic renal failure. Complete necropsy did not reveal an obvious cause of the hypertension, and histopathologic changes were limited to the cardiovascular system, eyes, and kidneys.
Renal function and pathologic changes in 27 dogs with pyometra were studied. Evaluation included CBC; serum biochemical evaluation; urinalysis; urine and uterine bacteriologic culture; uterine morphologic features; and light, electron, and immunofluorescent microscopic evaluation of renal tissues. Measurements of 24-hour creatinine clearance, protein excretion, Na excretion, and urine volume were made in 12 dogs without azotemia. Of 27 dogs, 26% were azotemic and 89% had a urine sp gr less than 1.035. Glomerular filtration rate was reduced in 75% of 12 dogs without azotemia. None of these 12 dogs was proteinuric. Examination of renal biopsy specimens revealed a high prevalence of mild tubulointerstitial nephritis, but few specific glomerular lesions. Minimal immunofluorescence was detected within the mesangium in 18% of the dogs. Immunofluorescence was not associated with the interstitium or tubules. Urinary tract infection was detected in 22% of the dogs. Escherichia coli and Klebsiella were recovered from the uterus in 59 and 15% of the dogs, respectively. Low urine specific gravity values were obtained from dogs without azotemia and from dogs with uterine cultures considered negative for E coli and other gram-negative bacteria. The reduction in glomerular filtration rate was a functional abnormality not correlated with structural damage in the glomerulus.
Spontaneous (not experimentally induced) systemic hypertension was detected in 5 male dogs that were examined because of apparent blindness caused by intraocular hemorrhage and/or retinal detachment. Secondary causes of hypertension, including renal, adrenal, and thyroid disease, were investigated. Four of the dogs had glomerulonephropathy, renal insufficiency, and proteinuria. Four dogs had compensatory cardiac hypertrophy. Hypertension in 4 of 5 dogs was associated with glomerulosclerosis with chronic renal insufficiency, bilateral adrenocortical hyperplasia, adrenocortical adenoma with renal amyloidosis, and immune-mediated glomerulonephritis with chronic renal insufficiency, respectively. The fifth dog was determined to have essential hypertension. The dogs were treated for their primary diseases. Sodium restriction alone was inadequate to reduce blood pressure; 4 of the dogs also required antihypertensive medications.
Disseminated paecilomycosis was diagnosed in an adult dog without underlying immunosuppressive disease. During the 3-month illness (before euthanasia), the dog had ulcerative granulomatous inguinal lymphadenitis, fever, anorexia, dyspnea, generalized lymphadenopathy, retinochoroiditis, and seizures. Fungal organisms isolated from inguinal and prescapular lymph nodes before the dog was euthanatized were identified histologically. Paecilomyces variotii was isolated from the prescapular lymph node specimen. Paecilomyces variotii may be more pathogenic (once it has gained bodily entry) than previously thought.
The presence of hypertension in domestic animals is poorly described. Values for hypertension were established in dogs using a direct blood pressure measurement. A protocol was devised to recognize and characterize primary (essential) and secondary hypertension. Essential hypertension was associated with marked elevations in blood pressure and can be shown to be a hereditary disease in dogs. Secondary hypertension is more common and most frequently associated with Cushing's disease and renal failure. Treatment to reduce blood pressure in both groups can be achieved using pharmacologic agents which are more effective than sodium restriction alone. Hypertension appears to be an underdiagnosed disease in dogs. The significance of chronic hypertension in dogs in terms of vascular pathology is not yet clear.
The objective of this project is to characterize a genetically determined model of essential hypertension in dogs. A pair of unrelated dogs with essential hypertension were identified. Breeding of these dogs and back-cross matings have resulted in 24 offspring, approximately half of which have essential hypertension (systolic blood pressure 170 mmHg, diastolic 105 mmHg). Other offspring are either borderline hypertensive or normal. Blood pressure is measured in the trained, unanaesthetized state by direct arterial puncture. Offspring have normal plasma chemistries, electrolytes, glomerular filtration rate, plasma renin activity, aldosterone and catecholamines. These dogs appear to salt-sensitive compared with normal dogs. Further breeding studies will characterize this new model of hereditary essential hypertension.