Complications following thiacetarsamide sodium therapy in Louisiana dogs with naturally-occurring heartworm disease

Four hundred and sixteen dogs with naturally-occurring heartworm disease were evaluated for complications following thiacetarsamide sodium therapy. Of these, 109 dogs (26.2%) experienced complications. Increased lung sounds was the most commonly seen complication, followed by fever and coughing. In dogs with complications, 83.5% of them presented without clinical evidence of pulmonary thromboembolism or heart failure. There were no statistically significant differences between the age, sex, breed and body size of dogs that experienced complications following thiacetarsamide therapy and dogs that did not. Complications were most frequently seen 5 to 9 days following thiacetarsamide therapy although some dogs experienced initial complications as late as 28 days. Thirty-three of 109 dogs (33.0%) with complications responded to exercise restriction. The remaining 76 dogs with complications prior to or following thiacetarsamide required adjunct drug therapy. Of these, 35 dogs responded favorably to anti-inflammatory doses of prednisolone or prednisone. Five dogs died or were euthanatized because of the complications experienced. Eighteen of 416 dogs (4.3%) presented with clinical evidence of pulmonary thromboembolism or heart failure prior to the thiacetarsamide therapy. All 18 dogs experienced complications in spite of adjunct drug therapy and exercise restriction prior to, during, and following thiacetarsamide therapy. Survival rate following resolution of the thiacetarsamide-induced complications was greater than 98%.     

Treatment of canine dirofilariasis: pulmonary thromboembolism caused by thiacetarsamide--microscopic changes

Light and scanning electron microscopies were used to study the pulmonary embolism occurring in Dirofilaria immitis-infected dogs after treatment with thiacetarsamide. Lesions in control dogs (nontreated) which had been infected for 4 weeks with 9 Dirofilaria immitis adults were compared with lesions occurring in infected dogs at 2 weeks and at 4 weeks after they were treated with the adulticide. Extensive thromboembolism occurred in the caudal lobar pulmonary arteries of dogs at posttreatment weeks 2 and 4. Complicated villous proliferations were present at posttreatment week 2. The characteristic myointimal proliferation of dirofilariasis showed resolution in the large pulmonary arteries of the dogs at week 4. However, the caudal lobar pulmonary arterial and lung lesions were more severe in the later group. The pathophysiology of adulticide-induced thromboembolism and associated lung parenchymal changes were discussed.     

Pulmonary thromboembolism during therapy of dirofilariasis with thiacetarsamide: modification with aspirin or prednisolone

The effects that 4 weeks of treatment of dirofilaria-infected dogs with either aspirin or prednisolone had on the pulmonary thromboembolism which occurs after they are given thiacetarsamide were determined, using light and electron microscopies. Pulmonary lesions in control dogs at 4 weeks after thiacetarsamide was given were compared with lesions in dogs which were treated with either aspirin (22 mg/kg daily) or prednisolone (1 mg/kg daily) during the 4-week period after adulticide was given. Pulmonary vascular and perivascular lesions were most severe in the prednisolone-treated dogs and least severe in the aspirin-treated dogs. The aspirin-treated dogs had greater resolution of pulmonary arterial proliferative disease, and prednisolone-treated dogs had the lesser resolution.     

An aspirin-prednisolone combination to modify postadulticide lung disease in heartworm-infected dogs

A combination of aspirin and prednisolone was used in an attempt to modify the pulmonary disease produced by thiacetarsamide treatment of heartworm-infected dogs. Results of 6 heartworm-infected dogs treated with prednisolone (1 mg/kg, daily for 4 weeks) and aspirin (10 mg/kg, daily for 4 weeks) after thiacetarsamide treatment were compared with previously published results of 3 groups of dogs (6 dogs/group). One of these 3 groups was a nontreated control group, another was treated with prednisolone, and the 3rd was treated with aspirin. All dogs, each with 9 adult heartworms transplanted, were treated with a 2-day, twice-a-day treatment of thiacetarsamide (1 mg/kg) 4 weeks after the transplant. Thoracic radiographs were taken before and at 1, 2, and 3 weeks after thiacetarsamide treatment to evaluate lung disease. Pulmonary arteriography was performed before and 3.5 weeks after thiacetarsamide treatment to evaluate pulmonary blood flow. After treatment, radiographs of the aspirin-prednisolone group were similar to radiographs of the prednisolone group, both with a marked attenuation of the parenchymal disease, as compared with the non-treated group. Addition of aspirin to prednisolone prevented the blood flow obstruction and intraluminal filling defects that were present in the groups not receiving aspirin. Sixteen of 54 transplanted heartworms survived thiacetarsamide treatment in both prednisolone-treated groups, in contrast to complete elimination of heartworms in the nontreated group. Aspirin may be considered for treatment of any heartworm-infected dog that does not have hemotypsis, but postthiacetarsamide use of prednisolone should be restricted to the dog that develops severe lung disease after the heartworms have been killed.     

Pneumonitis associated with occult heartworm disease in dogs

Nine of 69 dogs with occult heartworm disease (13%) had allergic pneumonitis characterized by consistent clinical and radiographic signs. Although the clinical signs were severe, the degree of radiographic pulmonary arterial abnormalities was mild. Corticosteroid therapy resulted in rapid resolution of clinical and radiographic signs; thiacetarsamide therapy was then given without complications. This syndrome may not be recognized as heartworm-associated and may be confused with other disorders, some being associated with a poor prognosis and requiring different therapy.     

LEVAMISOLE AS A MICROFILARICIDAL AGENT IN THE CONTROL OF CANINE DIROFILARIASIS

The effectiveness of levamisole hydrochloride as a microfilaricidal agent when used 3 weeks after thiacetarsamide sodium therapy for canine dirofilariasis, was studied in 6 experimental dogs and 20 clinical cases. The drug, when administered orally in gelatine capsules daily, cleared microfilariae from the circulation in the experimental dogs in 7 to 11 days. A dose rate of 10mg/kg appeared as effective as 15mg/kg. In the clinical group 70% of dogs had zero microfilarial counts after 4 to 8 doses at 10mg/kg daily. Vomiting, diarrhoea and inappetence were observed in some animals, but were not a significant problem. Elevations in plasma GPT and AP levels were recorded during the administration of levamisole in some dogs while GOT levels rose in 1 dog only. Urea and creatinine levels were unaffected in all dogs. The only haematological parameter affected was the eosinophil count which rose during levamisole administration. All levamisole-treated animals, were successfully commenced on daily DEC, as a prophylactic measure, while an anaphylactic-type reaction occurred when this drug was administered to 1 of the 2 control animals.     

犬恶丝虫病的药物治疗效果研究

本试验对24头恶丝虫病阳性犬的成虫选用硫砷酰胺钠进行驱杀,60d后再用左旋咪唑对幼虫进行驱杀,并设对照组。结果5个月后只有1头犬呈阳性;10个月后再次用ELISA检测,对照组有2头呈阳性,试验组仅1头呈阳性。表明硫砷胺酰胺钠杀灭犬恶丝虫成虫的效果比较好,有效率高达95%,但不能杀灭幼虫;左旋咪唑在该使用条件下能够有效杀灭幼虫。     

Platelet function, antithrombin-III activity, and fibrinogen concentration in heartworm-infected and heartworm-negative dogs treated with thiacetarsamide.

Platelet aggregation and release, platelet number, mean platelet volume, antithrombin-III activity, and fibrinogen concentration were evaluated in heartworm-negative and heartworm-infected dogs at baseline and on days 3, 10, and 21 after treatment with thiacetarsamide. Platelet reactivity was enhanced in a group of dogs naturally infected with Dirofilaria immitis, compared with 2 groups of heartworm-negative dogs, but platelet reactivity was not further enhanced after treatment with thiacetarsamide. A significant decrease in antithrombin-III activity was detected 21 days after treatment. The platelets from a group of laboratory Beagles implanted with 50 adult D immitis displayed enhanced reactivity 6 months after implantation, but by 18 months, platelet reactivity had returned to near, or less than, baseline. Platelet reactivity was enhanced after thiacetarsamide treatment in this group. Thiacetarsamide-associated changes were not observed in platelet number or size; antithrombin-III activity decreased, but the change was not significant. Fibrinogen concentration was increased significantly (P less than 0.05) on day 10. Enhanced adenosine diphosphate (ADP)-induced platelet aggregation was observed on days 3, 10, and 21 after treatment in heartworm-negative dogs. This change was not observed in 6 control Beagles not treated with thiacetarsamide. Although antithrombin-III activity was decreased on day 3 and fibrinogen concentration was increased on day 10, paralleling changes observed in the heartworm-infected dogs, the changes were not statistically significant. In this study, thiacetarsamide was procagulatory in heartworm-negative dogs and may be an important contributing factor to the thromboembolism observed with adulticidal therapy.     

Use of an antigen detection assay to determine mortality of Dirofilaria immitis after thiacetarsamide therapy

The use of an antigen detection enzyme immunoassay (EIA) to determine the post-treatment infection status of 16 dogs naturally infected with Dirofilaria immitis was investigated. Dogs were treated with thiacetarsamide at a dose rate of 12mg/4.5kg twice daily for 2 days, bled at regular intervals and necropsied 9 weeks later. The infection status of all dogs at necropsy was compared to the ratios of optical density (OD) values from the EIA using fresh plasma samples (day 60/day 0 = R60) and dogs were divided into 2 groups. Using the R60 ratios, those dogs with fewer than 2 live adult worms or immature worms at necropsy ("cleared" dogs) could be differentiated with 95% confidence from those dogs with more than 1 live adult worm ("non-cleared" dogs). Changes in the average OD values from the plasma of "cleared" dogs and "non-cleared" dogs were similar up to 46 days after treatment but diverged significantly thereafter. The efficacy of thiacetarsamide was 50% if all worms were considered and 75% if the presence of immature worms was ignored. The benefits of antigen detection assays for diagnosis and improved patient assessment and the use of an R60 ratio to assess the efficacy of adulticides such as thiacetarsamide are discussed in relation to their practical significance for clinicians.     

Fixed drug eruption in a dog

A reaction was encountered in an 18-month-old Dobermann Pinscher following chemotherapy for dirofilariasis. The treatment consisted of twice daily injections of the trivalent, organic arsenical, thiacetarsamide sodium for 2 days. A microfilaricide, dithiazine iodide, was administered orally 2 days later. The reaction consisted of prostration and respiratory distress of short duration, together with a cutaneous lesion which became evident 36 hr later. This lesion was characterized by oedema, necrosis and sloughing of a large area of skin from the lumbosacral region. A second course of thiacetarsamide sodium, given 55 months later, also produced an unusual reaction. It was considered that the cutaneous lesion encountered following the first treatment was a fixed drug eruption due to the thiacetarsamide sodium and that the dog had a specific hypersensitivity to this drug. Résumé. Il se produisit une réaction chez un chien Dobermann Pinscher de 18 mois à la suite de chimiothérapie pour la dirofilariose. Le traitement se composait d'injections deux fois par jour de sodium thiacetarsamide organique arsenical trivalent pendant deux jours. Un micro-filairicide, l'iodure dithiazine, fut donné par voie buccale deux jours après. La réaction se manifesta par un état de prostration et de gêne respiratoire de courte durée ainsi que par une lésion cutanée qui n'apparut que 36 heures après. Cette lésion avait pour caractéristiques: ?dème, nécrose et formation d'une escarre sur une grande surface de peau de la région lombo-sacrée. Un second traitement de sodium thiacetarsamide donné 5 1/2 mois plus tard produisit également une réaction extraordinaire. On pensa que la lésion cutanée qui avait eu lieu à la suite du premier traitement était une éruption particulière à un produit défini, causée en la circonstance par le sodium thiacetarsamide, et que le chien était hypersensible à ce produit en particulier. Zusammenfassung Bei einem 18 Monate alten Dobermann-Pinscher wurde nach chemo-therapeutischer Behandlung von Dirofilariasis eine Reaktion beobachtet. Die Behandlung bestand aus zweimalig täglicher Injektion von dreiwertigem organisch-arsenischen Thiacetarsamid-natrium für die Dauer von 2 Tagen. Ein Mikrofilarizid, Dithiazinjodid, wurde oral 2 Tage später verabreicht. Die Reaktion bestand aus Prostration und Atembeschwerden von kurzer Dauer sowie aus einer Hautläsion, die 36 Stunden spater in Erscheinung trat. Diese Läsion wurde durch Ödem, Nekrose und Hautablösung auf einer grossen Fläche der lumbosakralen Region charakterisiert. Eine zweite, 5 1/2 Monate später angewendete Behandlung mit Thiacetarsamidnatrium rief ebenfalls eine ungewöhnliche Reaktion hervor. Es wird die Ansicht geäussert, dass die Hautläsion nach der ersten Behandlung eine fixierte Medikamenteneruption durch Thiacetarsamidnatrium war und dass der Hund eine spezifische Hypersensibilität gegen dieses Medikament besass.     

Spontaneous echocardiographic contrast in three dogs

Objective – To describe the clinical presentation and outcome in 3 dogs with spontaneous echocardiographic contrast (SEC). Case or Series Summary – SEC was identified in 3 dogs with concurrent hyperfibrinogenemia. The dogs were diagnosed with different underlying conditions including infective endocarditis of the mitral valve (Case 1), presumptive Evan's syndrome (Case 2), and presumptive sepsis (Case 3). Various therapies were used in each case directed at their underlying condition, in addition to thromboprophylaxis that were based upon a perceived risk of thromboembolic disease. The 3 dogs in this series survived to discharge and had good outcome during the follow‐up period, which ranged from 3 weeks to 7 months. New or Unique Information Provided – SEC is considered a marker for thromboembolic disease in people and can occur in dogs in the absence of significant cardiomegaly. SEC in these 3 dogs may be related to the documented hyperfibrinogenemia. Further investigation is warranted to determine whether dogs with SEC are at an increased risk for thromboembolic complications.     

Clinical and laboratory observations in 91 dogs infected with Dirofilaria immitis in northern Greece

The medical records of 91 dogs with heartworm (Dirofilaria immitis) infection were reviewed, and diagnoses were established by using parasitological and immunological methods. Twenty-one animals were asymptomatic (stage I), 57 had mild to moderate clinical signs (stage II), and 13 had the severe form of the disease including right congestive heart failure and the caval syndrome (stage III). Thoracic radiography revealed right ventricular enlargement in 38 of the dogs, pulmonary vascular enlargement in 43, and parenchymal lesions in 27. Only the cardiac and vascular changes were correlated positively with the clinical stages. D. immitis microfilaraemia was detected in 75 of 85 dogs. Occult infection occurred only in eight stage II and two stage III dogs. Thirty-two of the dogs were treated with thiacetarsamide and 39 were treated with melarsomine, and no differences were found in terms of drug efficacy or complication rate; nine stage II dogs suffered pulmonary thromboembolism and one suffered acute liver disease and there were six fatalities. The 50 treated dogs in stages II and III which were followed up for six months all recovered completely. The performance of 38 of 61 working dogs was completely restored, and the performance of another four was partially restored.     

Thiacetarsamide in dogs with Dirofilaria immitis: influence of decreased liver function on drug efficacy

The influence that decreased functional hepatic mass had on blood arsenic concentrations in dogs after they were treated with thiacetarsamide, on the clearance of indocyanine green (ICG), on arsenic concentrations in the heartworm (Dirofilaria immitis), and on drug efficacy was studied. Dogs which were partially hepatectomized and treated with thiacetarsamide (1.76 mg/kg, 2 times a day for 2 days) had a significantly (P less than 0.01) reduced ICG clearance, significantly (P less than 0.01) higher arsenic levels in heartworms, and a significantly (P less than 0.01) higher proportion of heartworms killed than did dogs that were sham operated and treated with thiacetarsamide or sham operated and untreated. There were no significant differences in blood arsenic (thiacetarsamide) concentrations 2 minutes after injection between hepatectomized and nonhepatectomized groups. More male heartworms were killed than were female worms in the thiacetarsamide-treated groups. Indocyanine green half-life was longer (12.43 minutes) in the hepatectomized group than it was in the nonhepatectomized sham-operated groups (5.09 and 4.94 minutes). Indocyanine green clearance rate was lower in the hepatectomized group (0.54 ml/min/kg) than that in the nonhepatectomized groups (1.36 and 1.56 ml/min/kg). A parallel seemed to exist between ICG and thiacetarsamide removal from the blood by the liver. This parallel also was suggested in the higher worm arsenic (thiacetarsamide) concentrations for the hepatectomized group vs that for nonhepatectomized groups. Apparently, the slower the removal of thiacetarsamide from the blood by the liver, the higher the worm arsenic level and, consequently, the higher the worm kill.     

Clinicopathologic findings and outcome in dogs with infective endocarditis: 71 cases (1992-2005)

OBJECTIVES: To evaluate clinical, laboratory, and necropsy findings in dogs with infective endocarditis (IE). DESIGN: Retrospective case series. ANIMALS: 71 dogs with possible or definite IE. PROCEDURES: Medical records were reviewed for signalment, clinical features, and results of clinicopathologic testing and diagnostic imaging. Yearly incidence and the effect of variables on survival were determined by use of survival curve analysis. RESULTS: The overall incidence of IE was 0.05%. Most affected dogs were of large breeds, and > 75% were older than 5 years. The aortic valve was affected in 36 of the 71 (51%) dogs, and the mitral valve was affected in 59%. Lameness caused by immune-mediated polyarthritis, septic arthritis, or peripheral arterial thromboembolism was observed in 53% of the dogs. Neurologic complications were diagnosed in 17 of 71 (24%) dogs. Thromboembolic disease was suspected in 31 of 71 (44%) of dogs. The mortality rate associated with IE was 56%, and median survival time was 54 days. Factors negatively associated with survival included thrombocytopenia, high serum creatinine concentration, renal complications, and thromboembolic complications. CONCLUSIONS AND CLINICAL RELEVANCE: A diagnosis of IE should be suspected in dogs with fever, systolic or diastolic murmur, and locomotor problems. Dogs with thrombocytopenia, high serum creatinine concentration, thromboembolism, or renal complications may have a shorter survival time.     

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 Lymphomatoid Granulomatosis in Seven Dogs (1976–1987)

Seven dogs with pulmonary lymphomatoid granulomatosis were reviewed. The disease occurred in six large-breed and one small-breed dogs. The dogs were five to 14 years old (mean, 8.4; median, 7), and four of seven dogs were males. Three dogs had been previously treated with adulticide therapy for canine dirofilariasis. Clinical histories included a progressive respiratory disease characterized by varying degrees of cough, dyspnea, exercise intolerance, and weight loss. Thoracic radiographic features included hilar lymphadenopathy, pulmonary masses of varying sizes, and mixed pulmonary patterns of lobar consolidation with ill-defined interstitial and alveolar pulmonary infiltrates. Cardiovascular changes compatible with chronic dirofilariasis were present in three dogs. The clinical course was usually progressive and fatal. The survival time ranged from six days to four years (mean, 12.5 mos; median, 3 mos). Gross and histologic features included mass lesions with areas of necrosis that replaced normal pulmonary architecture. Cytologically, these lesions were characterized by infiltration with pleomorphic, angioinvasive mononuclear cells that often resulted in vascular obliteration. The infiltrating cells resembled large lymphoid cells that possessed large hyperchromatic nuclei and small amounts of cytoplasm. Systemic lymphoid neoplasia with peripheral lymphadenopathy was diagnosed in two dogs. In both cases, lymph-node cytology was similar to the cellular infiltrates found in the lungs and consistent with a diagnosis of lymphomatoid granulomatosis. These features are compared with previously reported cases of canine lymphomatoid granulomatosis and those features identified in a similar disease described in man.     

Seroprevalence of Dirofilaria immitis, feline leukemia virus, and feline immunodeficiency virus infection among dogs and cats exported from the 2005 Gulf Coast hurricane disaster area

OBJECTIVE: To determine seroprevalence of dirofilariasis in dogs and seroprevalences of dirofilariasis, FeLV infection, and FIV infection in cats exported from the Gulf Coast region following the 2005 hurricanes. DESIGN: Seroprevalence survey. ANIMALS: 1,958 dogs and 1,289 cats exported from Louisiana, Mississippi, and Texas between August 20 and December 31, 2005. PROCEDURES: 141 animal welfare groups in 37 states and Alberta, Canada, reported results of serologic testing. Risk factors for infection, including age, sex, neuter status, breed, and state of rescue, were examined by means of univariate and multivariate logistic regression. RESULTS: Seroprevalence of dirofilariasis in dogs was 48.8%. Sexually intact dogs were 1.6 times as likely to have dirofilariasis as were neutered dogs, dogs in the ancient breed group were 2.2 times as likely and dogs in the guarding breed group were 1.7 times as likely to have dirofilariasis as were dogs in the herding breed group, and dogs from Mississippi were significantly less likely to have dirofilariasis than were dogs from Texas. Seroprevalences of dirofilariasis, FeLV infection, and FIV infection in cats were 4.0%, 2.6%, and 3.6%, respectively. Seroprevalence of FIV infection was significantly higher in adult cats than in juveniles and in males than in females. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that dogs and cats exported from the 2005 Gulf Coast hurricane disaster area had disease rates similar to those for animals in the region prior to the hurricanes.     

Elevated endothelin-1 expression in dogs with heartworm disease

We explored the involvement of endothelin-1 (ET-1) in the pathophysiology of dog dirofilariasis (heartworm disease caused by Dirofilaria immitis) by analyzing mRNA levels of preproendothelin-1 (PPET-1), the precursor form of ET-1, in cardiopulmonary organs as well as ET-1 peptide levels in plasma. To determine the cDNA sequence and primary protein structure of dog PPET-1, we performed molecular cloning of the full-length cDNA. Based on the determined sequence information, comparative expression analysis of PPET-1 mRNA was carried out by real-time polymerase chain reaction on cardiopulmonary organs from healthy (n=5) and filarial (n=5) dogs. Filarial dogs showed a significantly (p<0.05) higher mRNA expression level in the heart (about one hundred times) and lung (about ten times) than healthy dogs. Analysis of plasma ET-1 levels in healthy (n=10) and filarial (n=10) dogs showed that filarial dogs (6.9+/-2.7 pg/ml) have significantly (p<0.01) increased plasma ET-1 levels compared with healthy dogs (1.4+/-0.3 pg/ml). To assess the pathophysiological significance of ET-1 in dirofilariasis relative to other cardiopulmonary disorders, plasma ET-1 levels determined in dogs diagnosed with mitral regurgitation (n=10), tricuspid regurgitation (n=5), ventricular septal defect (n=5), and patent ductus arteriosus (n=5) were compared to plasma ET-1 levels in filarial dogs. Filarial dogs, which commonly develop serious pulmonary hypertension, exhibited by far the highest ET-1 levels of the disease states examined. Based on the fact that ET-1 is a potent bioactive mediator that induces vasoconstriction and promotes vascular remodeling, these findings suggest that ET-1 plays an important role in the pathophysiology of dog dirofilariasis as an aggravating factor by inducing pulmonary hypertension.     

Indirect fluorescent antibody test in occult dirofilariasis.

Indirect fluorescent antibody titers to Dirofilaria immitis microfilaria (IFA-mf) and peripheral eosinophilia were recorded from 15 to 52 months in ten experimentally infected dogs with occult dirofilariasis (heartworm infection without microfilaremia). Five dogs which were experimentally sensitized with D immitis microfilaria did not exhibit microfilaremia after inoculation with infective-stage larvae. In three other dogs, microfilaremia suddenly ceased after 4 to 7 months. In these three dogs, antimicrofilarial antibodies were detectable by IFA-mf test as soon as microfilaremia ended. In the remaining two dogs, which exhibited spontaneous occult dirofilariasis, antibodies were detected at the end of the prepatent period of 6 months. The presence of adult worms was confirmed by angiocardiography. Significant IFA=mf titers (greater than or equal to 1:8) persisted after successful treatment with an adulticide. Reinfection of treated dogs reestablished occult dirofilarasis. Eosinophilia was present in all dogs and peaked at about 3, 6, and 9 months after they were inoculated with infective-stage larvae. At necropsy, the ten dogs harbored gravid, reproducing adult worms in the heart and pulmonary arteries.     

Effects of lactated Ringer solution and prednisolone sodium succinate on dogs with induced hemorrhagic shock.

Hemorrhagic shock was induced in nonsplenectomized dogs by removing 41% of their blood volume over a 15-minute period. Hemodynamic and metabolic variables were determined prior to and for 3 hours after completion of hemorrhage. One group of 5 dogs was not treated. After the 30-minute sample was collected, a second group of 5 dogs was given lactated Ringer solution (LRS) at 88 ml/kg of body weight, IV. A third group of 5 dogs was given LRS (88 ml/kg, IV) and prednisolone sodium succinate (11 mg/kg, IV) 30 minutes after hemorrhage. The IV administration of LRS was completed within 15 minutes. The glucocorticoid was administered as an IV bolus after 500 ml of LRS had been given. The large volume and administration of LRS significantly (P = 0.05) improved many of the hemodynamic and metabolic effects of acute hemorrhage and hemorrhagic shock. At one time or another during the 2.5-hour observation period after the initiation of treatment, mean arterial pressure, cardiac index, systemic vascular resistance, heart rate, respiratory rate, lactate, glucose, and arterial and venous blood gas values were significantly (P = 0.05) improved, compared with baseline values. The addition of prednisolone sodium succinate to the treatment regimen improved the effectiveness of LRS alone only in some dogs at random sampling times. Significant trends were not observed except, possibly, the improvement of venous pH and A-V pH and PCO2 differences.