Hypertension in Cats With Chronic Renal Failure or Hyperthyroidism

The Doppler ultrasonic recording technique was used to measure systolic and diastolic blood pressures indirectly in 28 cats with naturally occurring renal failure, 39 cats with hyperthyroidism, and 33 clinically normal cats. The mean systolic and diastolic blood pressures in the normal cats were 118.4 +/- 10.6 mm Hg and 83.8 +/- 12.2 mm Hg, respectively. In the cats with chronic renal failure, both the systolic (146.6 +/- 25.4 mm Hg) and diastolic (96.6 +/- 15.2 mm Hg) blood pressures were significantly higher (P less than 0.0001 and P less than 0.01, respectively) than in the normal cats. Elevations in systolic and/or diastolic blood pressure were recorded in 17 (61%) of the 28 cats with chronic renal failure. In the 39 untreated hyperthyroid cats, both the mean systolic (167.9 +/- 28.9 mm Hg) and diastolic (111.6 +/- 21.5 mm Hg) pressures also were significantly higher (P less than 0.0001) than normal. Increased systolic and/or diastolic blood pressure was recorded in 34 (87%) of the 39 hyperthyroid cats. In seven cats with hyperthyroidism that were reevaluated two to four months after successful treatment of the hyperthyroid state, there was a significant fall in mean systolic pressure (P less than 0.05) from a pretreatment value of 159.5 +/- 15.4 mm Hg to a posttreatment value of 132.0 +/- 1.62 mm Hg. Overall, the results of this study indicate that mild to moderate hypertension is common in cats with chronic renal failure and in cats with untreated hyperthyroidism. In addition, the hypertension appears to be reversible following successful treatment of the hyperthyroid state.     

Efficacy of atenolol as a single antihypertensive agent in hyperthyroid cats

beta-Adrenergic blockers, particularly atenolol, are often recommended for the tachycardia and hypertension that accompany hyperthyroidism; however, the effects of monotherapy with atenolol on both systolic blood pressure (SBP) and heart rate (HR) have not been reported. Twenty hyperthyroid cats with SBP > or = 160 mmHg were studied retrospectively to investigate the SBP and HR lowering effects of atenolol. Median pre-treatment SBP and HR for all cats were 186.5 mmHg and 231 beats/min, respectively. All cats were treated with atenolol at a dosage of 1-2 mg/kg PO q 12h for a minimum of 5 days prior to reassessment and treatment with radioactive iodine. SBP and HR both decreased following atenolol therapy in this group of cats to median values of 171.5 mmHg (P=0.0088) and 185/min (P=0.0003). However, when successful clinical control of hypertension was defined as a post-treatment SBP < 160 mmHg, atenolol monotherapy was ineffective in 70% of the cases. There was no statistically significant difference in baseline serum total thyroxine or atenolol dosage between clinical responders and non-responders. While atenolol effectively reduces HR in most cats with hyperthyroidism, elevated SBP is poorly controlled, and the addition of another vasodilator such as amlodipine or an angiotensin converting enzyme inhibitor is needed to treat associated hypertension.     

Effect of amlodipine on echocardiographic variables in cats with systemic hypertension

Left ventricular hypertrophy signals a poor prognosis in hypertensive humans. Cardiac disease is common in cats with systemic hypertension. The aims of this study were to characterize the echocardiographic findings of cats with systemic hypertension and to determine if reducing the degree of hypertension is associated with resolution of cardiac hypertrophy. Echocardiographic examinations were performed on 19 cats with naturally occurring systemic hypertension. Fourteen of these cats were subsequently studied after a minimum of 3 months of treatment with the antihypertensive agent amlodipine. Hypertensive cats had a significantly thicker interventricular septum in both systole and diastole, thicker left ventricular free wall in both systole and diastole, and larger left atrium compared to the published normal values and 74% (14/19) of the cats met criteria for left ventricular hypertrophy (diastolic septal or free-wall thickness > 0.60 cm). Systolic blood pressure was lower after treatment (217 +/- 25 mm Hg, range: 180-275 mm Hg; and 142 +/- 27 mm Hg, range: 90-200 mm Hg). No difference was found in any of the echocardiographic measurements between the untreated and treated cats, although more cats had ventricular hypertrophy before treatment (11/14) than after initiating amlodipine (6/14; P = .006). Ventricular hypertrophy is common in hypertensive cats and may resolve after the initiation of amlodipine.     

Reversible pulmonary hypertension presenting simultaneously with an atrial septal defect and angiostrongylosis in a dog

A one-year-old female neutered beagle was presented with marked abdominal effusion. Echocardiography showed marked dilatation of the right cardiac chambers, an atrial septal defect and severe tricuspid insufficiency. Systolic pulmonary arterial pressure (sPAP), evaluated by continuous wave Doppler echocardiography, was very high (80 mmHg), with a right to left interatrial shunt. The radiographic images were compatible with widespread pneumonitis. Numerous larvae of Angiostrongylus vasorum were visible on direct faecal examination. The animal was given fenbendazole for 15 days, combined with diuretics, an antibiotic and a vasodilator. Two weeks later, the dog showed a marked improvement. The treatment, except the anthelmintic, was continued for seven weeks and then stopped. At that stage, Doppler echocardiography revealed that the sPAP had returned to normal (20 mmHg) and the interatrial shunt had reversed (left to right). Eighteen months later, clinical and Doppler echocardiographic examinations were normal.     

Treatment of feline hyperthyroidism with radioactive iodine-131

Feline hyperthyroidism can be treated by thyroidectomy, antithyroid drugs, or radioactive iodine-131 (131I). The aim of this retrospective study was to evaluate the treatment of 83 hyperthyroid cats with 131I The dosage of 131I ranged from 4 to 6 milliCurie (mCi). Blood samples for determination of plasma concentrations of total thyroxine (TT4), urea, and creatinine were collected before, ten days after, and several months after treatment. In addition, arterial blood pressure was measured before and ten days after treatment. The median plasma TT4 concentration ten days after 131I treatment (27 nmol/L, 64 cats) was significantly lower than that before treatment (123 nmol/L). The median plasma TT4 concentration several months after 131I treatment was 22,5 nmol/L (40 cats). Ten days and several months after 131I treatment, plasma TT4 concentration had decreased below the upper limit of the reference range in 64 (77%) and 72 cats (87%), respectively. In four cats the plasma TT4 concentration had decreased below the lower limit of the reference range, but only two cats had symptoms of hypothyroidism. Plasma urea and creatinine concentrations were not increased ten days after 131I treatment, but the median plasma creatinine concentration was significantly higher several months after treatment when compared with before 131I treatment. Before treatment in 28 cats a high arterial blood pressure (> 180 mmHg) was measured, whereas after treatment in 25 cats a high arterial blood pressure was measured. The results of this study indicate that 131I treatment is an effective therapy in most cats with hyperthyroidism.     

Effects of mydriatics on intraocular pressure and pupil size in the normal feline eye

OBJECTIVE: To determine the effect of various mydriatics (1% atropine, 1% cyclopentolate, 0.5% tropicamide, 10% phenylephrine) on intraocular pressure (IOP) and pupil size (PS) in normal cats. ANIMALS STUDIED: The mydriatics were tested in 10 adult ophthalmoscopically normal European Domestic Short-haired cats. Procedure Single-dose drug studies were divided into placebo (vehicle of phenylephrine), 10% phenylephrine, 0.5% tropicamide, 1% cyclopentolate and 1% atropine. After measurement of IOP and pupil size (PS) at 8 a.m. on the first day, one drop of the tested drug was applied to one randomly selected eye. The IOP and PS were measured for a minimum of 36 h until the pupil returned to pretest size. RESULTS: Ten per cent phenylephrine had no significant effect on IOP, and the effect on the pupil size was minimal (相似文献   

Severe systemic hypertension in a cat with pituitary-dependent hyperadrenocorticism

A seven-year-old Burmese cat was presented with sudden onset blindness. On physical examination, the cat had bilateral retinal detachment and severe systemic hypertension. Further clinical investigations revealed pituitary-dependent hyperadrenocorticism. Antihypertensive therapy was discontinued when the hypertension resolved after bilateral adrenalectomy. Systolic blood pressure remained normal until 19 months post-operatively when systemic hypertension recurred and was attributed to chronic kidney disease. The cat was euthanased 47 months after initial presentation. A pituitary adenoma was identified at post-mortem examination. This case illustrates that systemic hypertension can occur secondary to hyperadrenocorticism in the cat.     

Clinical evaluation of the Surgivet V60046, a non invasive blood pressure monitor in anaesthetized dogs

OBJECTIVE: To compare the performance of the Surgivet Non-Invasive Blood Pressure (NIBP) monitor V60046 with an invasive blood pressure (IBP) technique in anaesthetized dogs. STUDY DESIGN: A prospective study. ANIMALS: Thirty-four dogs, anaesthetized for a variety of procedures. METHODS: Various anaesthetic protocols were used. Invasive blood pressure measurement was made using a catheter in the femoral or the pedal artery. A cuff was placed on the contralateral limb to allow non invasive measurements. Recordings of arterial blood pressures (ABPs) were taken at simultaneous times for a range of pressures. For analysis, three pressure levels were determined: high [systolic blood pressure (SAP) > 121 mmHg], normal (91 mmHg < SAP < 120 mmHg) and low (SAP < 90 mmHg). Comparisons between invasive and non invasive measurements were made using Bland-Altmann analysis. RESULTS: The NIBP monitor consistently underestimated blood pressure at all levels. The lowest biases and greatest precision were obtained at low and normal pressure levels for SAP and mean arterial pressure (MAP). At low blood pressure levels, the biases +/- 95% confidence interval (CI) were 1.9 +/- 2.96 mmHg (SAP), 8.3 +/- 2.41 mmHg diastolic arterial pressure (DAP) and 3.5 +/- 2.09 mmHg (MAP). At normal blood pressure levels, biases and CI were: 1.2 +/- 2.13 mmHg (SAP), 5.2 +/- 2.32 mmHg (DAP) and 2.1 +/- 1.54 mmHg (MAP). At high blood pressure levels, the biases and CI were 22.7 +/- 5.85 mmHg (SAP), 5.5 +/- 3.13 mmHg (DAP) and 9.4 +/- 3.52 mmHg (MAP). In 90.6% of cases of hypotension (MAP < 70 mmHg), the low blood pressure was correctly diagnosed by the Surgivet. CONCLUSIONS: Measurement of blood pressure with the indirect monitor allowed detection of hypotension using either SAP or MAP. The most accurate readings were determined for MAP at hypotensive and normal levels. The monitor lacked accuracy at high pressures. CLINICAL RELEVANCE: When severe challenges to the cardiovascular system are anticipated, an invasive method of recording ABP is preferable. For routine usage, the Surgivet monitor provided a reliable and safe method of NIBP monitoring in dogs, thereby contributing to the safety of anaesthesia by providing accurate information about the circulation.     

Primary hyperaldosteronism in the cat: a series of 13 cases

Thirteen cases of feline primary hyperaldosteronism were diagnosed based on clinical signs, serum biochemistry, plasma aldosterone concentration, adrenal imaging and histopathology of adrenal tissue. Two cases presented with blindness caused by systemic hypertension, whilst the remaining 11 cases showed weakness resulting from hypokalaemic polymyopathy. Elevated concentrations of plasma aldosterone and adrenocortical neoplasia were documented in all cases. Seven cases had adrenal adenomas (unilateral in five and bilateral in two) and six had unilateral adrenal carcinomas. Three cases underwent medical treatment only with amlodipine, spironolactone and potassium gluconate; two cases survived for 304 and 984 days until they were euthanased because of chronic renal failure, whilst the third case was euthanased at 50 days following failure of the owner to medicate the cat. Ten cases underwent surgical adrenalectomy following a successful stabilisation period on medical management. Five cases remain alive at the time of writing with follow-up periods of between 240 and 1803 days. Three cases were euthanased during or immediately following surgery because of surgical-induced haemorrhage. One cat was euthanased 14 days after surgery because of generalised sepsis, whilst the remaining cat was euthanased 1045 days after surgery because of anorexia and the development of a cranial abdominal mass. It is recommended that primary hyperaldosteronism should be considered as a differential diagnosis in middle-aged and older cats with hypokalaemic polymyopathy and/or systemic hypertension and should no longer be considered a rare condition.     

The effects of bimatoprost and unoprostone isopropyl on the intraocular pressure of normal cats

OBJECTIVE: To evaluate the effects on intraocular pressure (IOP), pupillary diameter (PD), blepharospasm score, conjunctival injection score, and aqueous humor flare score when either 0.03% bimatoprost solution is applied once daily or 0.15% unoprostone isopropyl solution is applied twice daily topically to the eyes of normal cats. MATERIALS AND METHODS: The aforementioned parameters were evaluated daily in each of 12 cats throughout the entirety of the study. During an initial 10-day treatment phase a single eye of six of the cats was treated with 0.03% bimatoprost solution while a single eye of the remaining six cats was treated with buffered saline solution (BSS) once daily. During a second 10-day treatment phase a single eye of six of the cats was treated with 0.15% unoprostone isopropyl solution while a single eye of the remaining six cats was treated with BSS twice daily. Contralateral eyes of all cats remained untreated at all time points. RESULTS: Blepharospasm score, conjunctival injection score, and aqueous humor flare score never rose from a value of 0, for any eye of any cat during the study. The mean +/- SD of IOP for eyes treated with 0.03% bimatoprost solution and BSS were 16.55 +/- 3.06 mmHg and 18.02 +/- 3.52 mmHg, respectively. The mean +/- of PD for eyes treated with 0.03% bimatoprost solution and BSS were 5.7 +/- 1.57 mm and 6.39 +/- 1.78 mm, respectively. The mean +/- SD of IOP for eyes treated with 0.15% unoprostone isopropyl solution and BSS were 15.7 +/- 2.91 mmHg and 17.2 +/- 2.9 mmHg, respectively. The mean +/- SD of PD for eyes treated with 0.15% unoprostone isopropyl solution and BSS were 5.8 +/- 1.43 mm and 6.9 +/- 1.37 mm, respectively. There was no significant difference (P > or = 0.05) in IOP or PD between eyes treated with 0.03% bimatoprost solution vs. eyes treated with BSS. Similarly, there was no significant difference (P > or = 0.05) in IOP or PD between eyes treated with 0.15% unoprostone isopropyl solution vs. eyes treated with BSS. CONCLUSION: Neither once daily topical administration of 0.03% bimatoprost solution nor twice daily topical administration of 0.15% unoprostone isopropyl solution significantly affect the IOP of normal cats. Both 0.03% bimatoprost solution and 0.15% unoprostone isopropyl solution induced no significant ocular side effects in normal cats when dosed over a 10-day treatment period.     

Retrospective evaluation of sildenafil citrate as a therapy for pulmonary hypertension in dogs

Pulmonary arterial hypertension (PH) is a pathologic condition in dogs characterized by abnormally high pressures in the pulmonary circulation and has been associated with a poor outcome. Sildenafil is a type V phosphodiesterase inhibitor that produces nitric oxide mediated vasodilatation. Sildenafil treatment decreases pulmonary arterial pressure and pulmonary vascular resistance in people with PH. The purpose of this study was to describe the clinical characteristics and outcome of dogs with PH treated with sildenafil. The cardiology database was searched for dogs with PH treated with sildenafil. PH was defined as systolic pulmonary arterial pressure (PAPs) > or = 25 mmHg at rest. Medical records were reviewed for the following information: signalment, duration and type of clinical signs before treatment, underlying disease, estimated or measured PAPs, dosage and dosing interval of sildenafil, and the effect of treatment on clinical signs and pulmonary arterial pressure and survival time. Thirteen affected dogs were identified. Clinical signs included collapse, syncope, respiratory distress, and cough. Duration of clinical signs before presentation ranged from 3 days to 5 months. An underlying cause was identified in 8 dogs. The median sildenafil dosage was 1.9 mg/kg. Ten dogs received concurrent medications. Median PAPs was 90 mmHg; 8 dogs were reevaluated after therapy, and the median decrease in PAPs was 16.5 mmHg. The median survival time of all dogs was 91 days. Sildenafil appeared to be well tolerated in dogs with PH and was associated with decreased PAPs and amelioration of clinical signs in most. Sildenafil represents a reasonable treatment option for dogs with pulmonary hypertension.     

Pulmonary wedge pressure and heart frequency measurements during standardized treadmill exercise for extension of left atrial function diagnosis in warmblood horses

In 12 healthy warmblood horses (six trained and six untrained) the pulmonary wedge pressure and heart frequency was measured at rest and during a standardised exercise test on a treadmill. The mean pulmonary wedge pressure at rest was 14.53 +/- 2.36 mmHg. There was no significant difference in pulmonary wedge pressure either at rest or during exercise between trained and untrained horses. During walking (1.8 m/s) the mean pulmonary wedge pressure was 19.62 +/- 4.03 mmHg, during trotting (4 und 5 m/s) it was between 22.38 +/- 3.92 mmHg and 25.28 +/- 3.7 mmHg. During canter (6 m/s) and gallop (8 m/s) the mean pulmonary wedge pressure increased to a level of 25.54 +/- 4.3 mmHg and 31.86 +/- 4.29 mmHg. There was a significant increase in pulmonary wedge pressure with each incremental step of the standardised treadmill test. Concerning mean heart frequency a highly significant increase could be observed at the beginning and at the end (treadmill speed of 7 and 8 m/s) of the standardised exercise test. At higher intensity of the exercise test (7 m/s and 8 m/s) untrained horses showed a significantly increased heart rate compared to trained horses. Neither at rest nor during the different exercise levels a significant correlation factor greater 0.5 between heart frequency and pulmonary wedge pressure could be observed. The increase of heart frequency and pulmonary wedge pressure during exercise showed no correlation. Between left atrial size and pulmonary wedge pressure a statistical weak correlation could be observed up to a treadmill velocity of 6 and 7 m/s.     

Essential hypertension in a dog

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.     

Comparison of the effects of topical administration of a fixed combination of dorzolamide-timolol to monotherapy with timolol or dorzolamide on IOP, pupil size, and heart rate in glaucomatous dogs

OBJECTIVE: To determine whether the combination multiple-dose dorzolamide-timolol administered topically has any greater effects on the reduction of intraocular pressure, pupil size, and heart rate in dogs with glaucoma than do either timolol or dorzolamide alone. PROCEDURE: Applanation tonometry, pupil size, and heart rate measurements were made at 7 a.m., 1 p.m., and 7 p.m. daily of 12 laboratory Beagles with inherited primary open-angle glaucoma during each active phase of this study. Timolol 0.5% was administered first twice daily for 4 consecutive days. Dorzolamide 2.0% was administered next three times daily for 4 consecutive days. The fixed combination of the two (timolol 0.5% and dorzolamide 2.0%) was administered twice daily for 4 consecutive days during the final week of the study. Between administration of each drug, a withdrawal period of at least 10 days was instituted. Statistical comparisons between the effects of the three drugs were performed. RESULTS: Intraocular pressure (IOP) was decreased with the administration of all three drugs: timolol alone, dorzolamide alone, and the combination of the two decreased IOP after 1 day of treatment 2.83 +/- 0.70 mmHg, 6.47 +/- 0.32 mmHg, and 6.56 +/- 0.37 mmHg, respectively. After 4 days of treatment, the IOP decreased even further: timolol alone, dorzolamide alone, and the combination of the two decreased IOP 3.75 +/- 0.88 mmHg, 7.50 +/- 0.29 mmHg, and 8.42 +/- 0.58 mmHg, respectively. Heart rate was significantly decreased with timolol (-11.9 +/- 2.0 bpm) and the combination preparation (-8.6 + 2.4 bpm), but not with dorzolamide (-3.7 +/- 1.8 bpm) alone. Pupil size was significantly decreased with timolol (-1.42 + 0.40 mm) and the combination preparation (-1.3 + 0.33 mm), but not with dorzolamide (0.97 +/- 0.36 mm) alone. CONCLUSIONS: The combination dorzolamide-timolol appears to be more effective at reducing intraocular pressure in glaucomatous dogs than is either timolol or dorzolamide alone.     

Spontaneous feline hypertension: clinical and echocardiographic abnormalities,and survival rate

Systemic hypertension was diagnosed in 58 of 188 untreated cats referred for evaluation of suspected hypertension-associated ocular, neurologic. cardiorespiratory, and urinary disease, or diseases frequently associated with hypertension (hyperthyroidism and chronic renal failure). Hypertensive cats were significantly older than normotensive subjects (13.0 +/- 3.5 years versus 9.6 +/- 5.0 years; P < .01), and had a greater prevalence of retinal lesions (48 versus 3%; P < .001), gallop rhythm (16 versus 0%; P < .001), and polyuria-polydipsia (53 versus 29%: P < .01). Blood pressure was significantly higher (P < .001) in cats with retinopathies (262 +/- 34 mm Hg) than in other hypertensive animals (221 +/- 34 mm Hg). Hypertensive cats had a thicker interventricular septum (5.8 +/- 1.7 versus 3.7 +/- 0.64 mm; P < .001) and left ventricular free wall (6.2 +/- 1.6 versus 4.1 +/- 0.51 mm; P < .001) and a reduced diastolic left ventricular internal diameter (13.5 +/- 3.2 versus 15.8 +/- 0.72 mm; P < .001) than control cats. Left ventricular geometry was abnormal in 33 of 39 hypertensive subjects. No significant difference was found in age or blood pressure at the initial visit between cats that died or survived over a 9-month period after initial diagnosis of hypertension. Mean survival times were not significantly different between hypertensive cats with normal and abnormal left ventricular patterns. Further prospective studies are needed to clearly identify the factors involved in survival time in hypertensive cats.     

Importance of uniform cuff application for equine blood pressure measurement

Seventeen horses were used to determine the variances associated with blood pressure cuff application (Sp2) and with other inherent errors (So2). Systolic pressure values had Sp2 = 3.9 mmHg and So2 = 5.6 mmHg, while diastolic pressure values had Sp2 = 1.1 mmHg and So2 = 4.4 mmHg. Thus, to be considered different, two blood pressure means (in mmHg), each derived from three readings, had to differ by at least 3.9 for systolic pressure and 3.4 for diastolic pressure when all readings were made without cuff displacement; 6.8 for systolic pressure and 4.6 for diastolic pressure when the cuff was reapplied between, but not during, measurement of each mean; and 5.0 for systolic pressure and 3.8 for diastolic pressure when the cuff was reapplied between all readings. It was concluded that uniform cuff application is readily achieved.     

LONG-TERM FOLLOW-UP OF HYPERTHYROID CATS TREATED WITH IODINE-131

A long-term follow-up study of hyperthyroid cats treated with iodine-131 was conducted at the Texas A&M University Veterinary Teaching Hospital. Between January 1985 and December 1990, 255 cats were treated. Basic demographic data, information on treatment, and diseases at the time of diagnosis were recorded. Two hundred and thirty seven cats had long-term follow-up data collected by telephone interviews with the referring veterinarian and/or the owner on outcome of therapy, diseases that developed during the follow-up period and survival. Risk for developing hyperthyroidism was highest for cats greater than 10 years of age. There was no breed predisposition. Neutered cats were slightly over-represented among the cases compared to intact animals. Eighty-five percent of treated cats became clinically normal and remained euthyroid for a median time of 17.5 months. Four percent remained hyperthyroid and 9% became hypothyroid, requiring thyroid hormone supplementation.     

Cutaneous reactive histiocytosis in dogs: a retrospective evaluation of 32 cases

Thirty-two cases of canine cutaneous histiocytosis were retrospectively evaluated. Median age at onset was 4 years. Lesions included nodules and plaques affecting the head/face, trunk and limbs, and erythema, swelling and depigmentation of the nasal planum/nares. Systemic involvement was not ruled out in all cases. All dogs had complete resolution of dermatological lesions after initial treatment (median 45 days). Initial treatment included prednisone +/- antibiotics (12 of 32 dogs), prednisone and tetracycline/niacinamide (four of 32), prednisone and azathioprine (three of 32), tetracycline/niacinamide +/- vitamin E/essential fatty acids (six of 32), antibiotics +/- antihistamines (three of 32), cyclosporine and ketoconazole (one of 32), topical therapy (two of 32), and no treatment (one of 32). Seventeen dogs received maintenance therapy which consisted of tetracycline/niacinamide +/- vitamin E/essential fatty acids (12 of 17), cyclosporine/ketoconazole (two to three times a week) (two of 17), azathioprine daily (one of 17), prednisone/azathioprine (two times a week) (one of 17), and prednisone daily (one of 17). Median follow up was 25 months. Nine dogs had a recurrence of cutaneous histiocytosis (median days to recurrence 130 days), with seven of nine having more than one recurrence. At study completion, six dogs were deceased (no lesions at the time of death) and 26 of 32 were alive with no lesions. Ten of 26 dogs were on maintenance treatment (eight tetracycline/niacinamide, one azathioprine, one vitamin E). Previous dermatological disease and season had no detectable influence on recurrence. Recurrence was significantly more likely in dogs with nasal planum/nares lesions than dogs without these lesions. Tetracycline/niacinamide was an effective treatment option for dogs in this study population.     

Contribution of live heartworms harboring in pulmonary arteries to pulmonary hypertension in dogs with dirofilariasis

To investigate whether adult heartworms harboring in the pulmonary arteries contribute to pulmonary hypertension, we determined the cardio-pulmonary values immediately before and after removal of heartworms from the pulmonary arteries and before and after insertion of live worms in their place. In 10 heartworm-infected dogs, 8 to 46 worms were removed. The mean pulmonary arterial pressure fell significantly from 24.5 +/- 7.9 mmHg to 16.3 +/- 4.9 mmHg (p less than 0.01) immediately after removal. The right cardiac output decreased in 7 of the 10 cases. The total pulmonary resistance and right ventricular stroke work index also decreased. At 24 hours after removal, live heartworms were put back into the pulmonary arteries of their host dog. The mean pulmonary arterial pressure elevated significantly (p less than 0.01) immediately after insertion. The right cardiac output further decreased in 7 of the 10 dogs, and the total pulmonary resistance and right ventricular stroke work index increased. Separate from this, 12 to 42 heartworms were transplanted into the pulmonary arteries of 5 heartworm-free dogs. Immediately after transplantation, the pulmonary arterial pressure did not show any significant change. However, the stroke volume decreased, and the total pulmonary resistance increased. These facts suggest a contribution of live heartworms to the pulmonary hypertension, although there is a complicated interaction among the presence of heartworms, the pulmonary lesions and the pulmonary hypertension.