Salivary mucocele associated with dirofilariasis in a dog.

Salivary mucocele associated with dirofilariasis was diagnosed in a dog with a mass in the cranioventral cervical region. The diagnosis was based on the finding of microfilariae in fluid aspirated from the mucocele, immunoassay confirmation of circulating Dirofilaria immitis antigen, and the finding of an adult filariid within the mucocele. Drainage of the mucocele and treatment of the D immitis infection resulted in resolution of the mucocele and dirofilariasis.

Alternative treatment of heartworm disease.

Conventional adulticidal therapy may cause acute death due to embolism in major pulmonary arteries resulting in severe infarction of the lung. To avoid this problem removing a significant number of worms with flexible alligator forceps prior to adulticidal therapy is recommended. Before surgery, an accurate diagnosis and critical evaluation of the patient is mandated for proper choice and sequence of treatment.

Diagnóstico de dirofilariose oculta pelo teste de ELISA, em cäes do Estado de Säo Paulo / Diagnosis of canine dirofilariasis, by ELISA test, in the State of Säo Paulo

A dirofilariose oculta constitui-se num grande problema diagnóstico e pode estar relacionada a: a) infecçöes pré-patentes; b) infecçöes causadas por vermes de um único sexo; c) esterilidade dos parasitas devido à idade ou induzida por açäo de drogas; d) resposta imune mediada. Avaliou-se, no presente trabalho, a prevalência de dirofilariose em cäes do Estado de Säo Paulo, através do teste de ELISA (CITER Semi-QuantTM Canine Heartworm Antigen Test Kit), bem como se tentou caracterizar a causa da ausência de microfilaremia circulante, com auxílio de exames subsidiários. De 244 soros examinados, 35 (14,34//) mostraram-se positivos. Destes, 20 apresentaram, além do teste de ELISA positivo, uma ou mais alteraçöes (radiográficas/eletrocardiográficas), compatíveis com o diagnóstico de dirofilariose canina; e, nos demais 15 animais, assintomáticos, também soropositivos pelo teste de ELISA, descartou-se a forma de infecçäo pré-patente, pois haviam sido expostos ao risco da infecçäo há mais de 6 meses, e também a esterilidade dos parasitas conseqüentemente à açäo de drogas

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.

Effects of treatment with aspirin or aspirin/dipyridamole combination in heartworm-negative, heartworm-infected, and embolized heartworm-infected dogs.

To determine the drug dose required to inhibit platelet reactivity by at least 50%, 2 drug regimens were evaluated in heartworm-negative, heartworm-infected, and heartworm-infected dogs embolized with dead heartworms. Aspirin, or a combination of aspirin and dipyridamole, were administered to 2 groups of Beagles (n = 5 each) for 5 to 9 days; a third group of 5 Beagles served as nontreated controls. For heartworm-negative dogs, mean (+/- SD) aspirin dosage that inhibited collagen-induced platelet reactivity by at least 50% was 6 (+/- 2) mg/kg of body weight given once daily. The aspirin/diphridamole combination dosage was 1 mg of each drug/kg given every 12 hours. All dogs (n = 15) were implanted with 7 adult heartworms each and remedicated (or not treated) beginning at 21 days after heartworm implantation. In heartworm-infected dogs, mean aspirin dosage required to inhibit collagen-induced platelet reactivity greater than or equal to 50% was 10 (+/- 6) mg/kg. Mean dosage of aspirin/dipyridamole combination was 1.6 +/- (0.5) mg of each drug/kg given every 12 hours. When platelet reactivity in response to collagen was determined to be inhibited by at least 50% in all medicated dogs, each dog (n = 15) was embolized with 7 dead adult heartworms to mimic heartworm adulticidal treatment. Platelet reactivity was monitored for 21 days after treatment, and drug dose was adjusted to maintain platelet inhibition by at least 50%. In embolized dogs, mean aspirin dosage was 17 (+/- 14) mg/kg given once daily. Mean dosage of the aspirin/dipyridamole combination was 2.8 (+/- 1.3) mg of each drug/kg given every 12 hours. All dogs (n = 15) were euthanatized 21 days after heartworm embolization. Each lung lobe was evaluated for severity of lesions and presence of organized or fibrinous thrombi. Lesion severity in the aspirin- and aspirin/dipyridamole-treated dogs was not significantly different from that in control dogs.

Effects of treatment with ticlopidine in heartworm-negative, heartworm-infected, and embolized heartworm-infected dogs.

Ticlopidine hydrochloride was evaluated for its effectiveness in inhibiting platelet aggregation and serotonin release in 5 laboratory Beagles before and after heartworm implantation with 7 adult Dirofilaria immitis, and after embolization with 7 dead heartworms to mimic what happens after heartworm adulticide treatment. Five other laboratory Beagles, similarly implanted and embolized with heartworms, were used as nonmedicated controls. During the heartworm-negative stage, the dosage of ticlopidine that inhibited adenosine diphosphate (ADP)-induced platelet aggregation in 5 dogs by at least 50% after 5 days of treatment was 62 mg/kg of body weight once a day. In the same dogs implanted with 7 adult heartworms 21 days previously, mean (+/- SD) ticlopidine dosage required to obtain similar results was 71 (+/- 13) mg/kg given once daily. During the 21 days after dead heartworms were implanted in heartworm-infected dogs, mean ticlopidine dosage was 108 (+/- 35) mg/kg (range, 62 to 150 mg/kg). Ticlopidine treatment was associated with increased platelet numbers in all 5 dogs during the heartworm-negative stage and in 4 of 5 dogs during the heartworm implantation and heartworm embolization stages. Mean platelet volume tended to decrease as platelet numbers increased. At necropsy, gross and histologic pulmonary lesions were less severe in ticlopidine-treated dogs than in nonmedicated control dogs.

Immunoperoxidase staining characteristics of Dirofilaria immitis in the dog.

The immunoperoxidase staining characteristics of Dirofilaria immitis and pulmonary tissues from infected dogs were studied by using the following sera: anti-fresh D immitis, anti-processed D immitis, anti-dog IgG, anti-dog IgG Fc, anti-dog IgM and anti-dog C3. Marked staining was observed using anti-fresh D immitis serum. Body cavity fluid and cuticle were strongly stained and hypodermis, muscle, lateral cord, testis, vas deferens, ovary, oviduct and uterus were moderately stained. Oesophagus and intestine were mildly stained. Degenerate worms were stained by all antisera. The intact and cut surfaces of microfilariae and eggs and sperm present in filariae were stained, but not their internal contents. Circulating and stored immotile microfilariae did not stain. Excreted eggs, presumed to be unfertilized and, or, degenerate, stained positively. Immunoperoxidase staining of routinely processed histological samples provides a means of assessing D immitis antigen.

Improvement in pulmonary arterial lesions after heartworm removal using flexible alligator forceps.

Improvement of pulmonary arterial lesions after heartworm removal using flexible alligator forceps was investigated by measuring pulmonary arterial pressure (PAP), and by angiographic and histopathological examinations in 11 dogs. PAP obtained immediately after worm removal corresponded well with angiographic abnormalities. In 2 dogs, high PAP immediately after worm removal fell gradually by 12 weeks, and obstructions on angiogram were resolved at 4 to 12 weeks. In 4 dogs, slightly high PAP fell to the normal range at 4 weeks, and angiographic abnormalities were considerably reduced at 4 to 12 weeks. In 5 dogs, PAP returned to normal range immediately after worm removal, and angiographic changes almost disappeared at 4 to 8 weeks. On biopsy immediately after worm removal, samples of the main pulmonary arteries showed severe intimal proliferations with villous or papillary protrusion into the lumen. Autopsy at 12 to 20 weeks indicated that the intimal protrusions were remarkably reduced as compared with the biopsy samples in all cases. However, villous intimal protrusions were seen in the caudal lobar arteries in cases with remaining alive worms. New vessels seemed to develop into thromboemboli with time. From these findings, it is clear that the pulmonary arterial lesions improved after heartworm removal, and the clinical signs disappeared following the improvement in hemodynamics. Aspirin therapy (5 mg/kg/day) for 4 weeks after worm removal in 5 dogs did not improve the intimal lesions as compared to 3 control dogs.

Chylothorax associated with dirofilariasis in a cat.

A 4-year-old castrated domestic shorthair cat was referred for treatment of chylothorax. Thoracic duct lymphangiography revealed partial obstruction of the cranial vena cava, as evidenced by filling of mediastinal lymphatics with dye instead of all of the dye entering the vena cava. The thoracic duct was ligated via left 10th intercostal space thoracotomy. Immediate postligation lymphangiography revealed successful duct ligation. Results of a serum ELISA for adult heartworm antigen that was performed before surgery were positive. Drug treatment for the heartworm disease was not recommended, because the pleural effusion had ceased (as determined by radiographic examination 3.5 and 9 months after surgery) and the cat was doing well clinically. Sixteen months after surgery, the owner reported that the cat was doing well and did not have signs of respiratory problems.

Persistent hematuria in a dog with renal hemangioma.

Persistent hematuria in a neutered male Collie failed to resolve after treatment for adult Dirofilaria immitis. Excretory urography revealed normal opacification and an hourglass-shaped right kidney, with distortion of the renal pelvis and diverticula. After ureteronephrectomy, recovery was uncomplicated, and hematuria ceased 2 weeks after surgery. The middle of the excised kidney had been replaced with blood-filled spaces that were consistent with histopathologic diagnosis of hemangioma.

Enhanced platelet reactivity in heartworm-infected dogs.

Platelet number, mean platelet volume, and platelet function were evaluated in 34 clinically normal dogs and 28 heartworm-infected (HWI) dogs. Mean platelet numbers for dogs of the HWI group was not significantly lower than those for dogs of the control group (214,000 vs 254,000 cells/microliter); however, 6 (21%) HWI dogs had platelet numbers less than 150,000/microliter, compared with only 2 (6%) heartworm-negative dogs. The mean platelet volume was not significantly different (7.8 vs 7.7 fl) between the 2 groups of dogs. Mean platelet aggregation responses to intermediate and low concentrations of collagen (3.0 and 1.5 micrograms) and to high, intermediate, and low concentrations of ADP (25, 10, and 5 microM) were greater in dogs of the HWI group. Mean platelet 14C-serotonin release was also greater in HWI dogs in response to high concentration of ADP (25 microM) and to intermediate concentration of collagen (3.0 micrograms).

Nine-month evaluation of dogs after open-heart surgical removal of heartworms.

Adult heartworms were surgically removed from 4 infected dogs by use of intracardiac techniques during cardiopulmonary bypass. The number of worms removed ranged from 12 to 14 per dog. Observation for 9 months after surgery gave no clinical evidence of active adult heartworm infection, in spite of the consistent finding of circulating microfilariae during the follow-up period. There were no significant early or late postoperative complications. Results of postoperative hematologic and biochemical studies were unremarkable. At necropsy (following euthanasia, 9 months after surgery) the heart and pulmonary arteries of all dogs were free of adult heartworms; pathologic changes attributable to residual infection were not found.