Efficacy of milbemycin oxime in chemoprophylaxis of dirofilariasis in cats

Although cats are less susceptible to infection with Dirofilaria immitis than are dogs, the possibility of severe consequences from infection or adulticidal treatment renders preventive treatment a desirable alternative in endemic areas. To evaluate the efficacy of milbemycin oxime as a chemoprophylactic agent in cats, 48 cats were inoculated with infective D immitis larvae. Single oral treatment with 2.3 mg of milbemycin oxime (0.5 to 0.9 mg/kg of body weight) at 30 or 60 days after inoculation with infective larvae gave strong but incomplete protection. Treatment at 60, as well as 90, days after inoculation with infective larvae was completely effective in preventing development of infection. A control group of inoculated, but untreated, cats was monitored biweekly for hematologic changes and for changes in parasite-specific serum antigen and antibody concentrations. Pronounced increases in total leukocyte counts and eosinophil numbers were associated with the estimated time of in vivo molting from fourth- to fifth-stage larvae. Antibody reactivity correlated with infection status, but serum antigen concentrations through 161 days after inoculation were undetectable.

Efficacy of milbemycin oxime against naturally acquired or experimentally induced Ancylostoma spp and Trichuris vulpis infections in dogs

The efficacy of milbemycin oxime was evaluated at dosages of 0.25, 0.50, and 0.75 mg/kg of body weight in dogs naturally infected with mature Ancylostoma spp, at a dosage of 0.50 mg/kg in dogs with experimentally induced immature and mature A caninum, and at dosages of 0.55 to 0.86 mg/kg in dogs naturally infected with mature Trichuris vulpis. Milbemycin oxime was 95 and 99% effective against mature Ancylostoma spp at dosages of 0.50 and 0.75 mg/kg, respectively, but only 49% effective at a dosage of 0.25 mg/kg. Efficacy was 49% against pulmonary L3-L4 stages of A caninum (36 hours after inoculation), greater than 80% against L4 (120 hours after inoculation) and early L5 stages (216 hours after inoculation), and greater than 90% against experimentally induced mature stages (360 hours after inoculation). Milbemycin oxime was also 97% effective in the removal of mature Tr vulpis from naturally infected dogs. Adverse reactions were not observed following treatment in any of the dogs.

Chemoprophylactic effects of milbemycin oxime against larvae of Dirofilaria immitis during prepatent development

Three studies were conducted to determine the efficacy of milbemycin oxime in the prevention of Dirofilaria immitis infection in dogs. Dogs were given single or multiple experimental inoculations with infective third-stage D immitis larvae and were treated with milbemycin oxime at a target dosage of 0.5 mg/kg of body weight either once or at monthly intervals at various times after inoculation. The compound was effective in preventing infection when 1 dose was administered 30 or 45 days after inoculation. Significant, but incomplete, protection was achieved when single treatments were administered 60 or 90 days after inoculation. Multiple monthly treatments beginning 60 days after inoculation appeared to provide additive effects that resulted in restoration of complete efficacy.

Effects of nitroscanate on adult Taenia pisiformis in dogs with experimentally induced infections

Twenty-four specific-pathogen-free Beagles were each given 50 cysticerci of Taenia pisiformis that had been harvested from experimentally infected rabbits. Quantitative fecal egg counts and fecal screening for recovery of passed segments were performed on postinoculation days 56 through 70. Twenty-three of 24 dogs fed cysticerci developed patent infections. The 23 dogs with patent infections were assigned to 1 of 2 groups and treated with nitroscanate or a placebo 60 days after inoculation. Egg counts in the treated dogs had markedly decreased by the second day after treatment, and by the sixth day after treatment, segments were not found in the feces of any of the treated animals. The control dogs continued to pass eggs and segments in their feces throughout the 9 days after treatment. The dogs were euthanatized and necropsied 70 days after being inoculated. At necropsy, the mean number of scolices recovered from control dogs was 24.6, the mean number of scolices recovered from treated dogs was 0.25. Worms recovered from the control dogs were intact, gravid cestodes. Efficacy of treatment with nitroscanate at a mean dosage of 56 mg/kg of body weight was 98.9%.

Effect of milbemycin oxime against Ancylostoma caninum in dogs with naturally acquired infection

Twenty-six mixed-breed (14 males, 12 females) dogs were used in a double-blind study to evaluate the effect of milbemycin oxime against naturally acquired infection with Ancylostoma caninum. Dogs were ranked and paired, on the basis of number of hookworm eggs/g of feces, and treatment was randomly assigned. Each dog was given either the study drug or placebo (1 tablet/11.4 kg [0.5 mg/kg] of body weight). Eggs per gram of feces enumeration was done on days 3 and 7 after treatment, and dogs were euthanatized on day 7. On day 3, 5 of the 13 dogs in the milbemycin-treated group had hookworm eggs in the feces (results of the McMaster test). In these dogs, mean number of eggs per gram of feces had decreased markedly (from 5,289 to 452) and, by day 7, was 114. At necropsy, 16 A caninum adults were recovered from 2 of the milbemycin-treated dogs. On day 3, 12 of the 13 dogs in the placebo-treated group had hookworm eggs in the feces. Mean number of eggs per gram of feces in these dogs decreased slightly (from 5,243 to 2,646), but did not decrease further by day 7. A mean number of 54.4 A caninum adults was recovered from 12 of the 13 placebo-treated dogs at necropsy. Milbemycin oxime had 97.8% efficacy against A caninum. Results also indicated that milbemycin oxime may be effective against Trichuris vulpis, but not against Dipylidium caninum.

Effects of milbemycin oxime on adult hookworms in dogs with naturally acquired infections

Previous work indicated that adult Ancylostoma caninum can be removed from experimentally infected dogs, using a formulation of milbemycin oxime at dosage of 0.5 mg/kg of body weight. To determine the efficacy of this treatment in dogs naturally infected with adult hookworms, 24 mixed-breed dogs with patent hookworm infections were purchased from an out-of-state vendor, and 6 male and 6 female dogs were assigned to either a control group or a group that would be treated. Dogs were treated 10 days after their arrival and were euthanatized 1 week after treatment. Beginning 3 days before treatment, fecal samples were collected daily from all dogs, and the number of Ancylostoma eggs per gram of dry weight of feces was determined from each sample. By 1 week after treatment, the mean number of eggs being passed by the treated dogs had dropped from 12,700 to 10 eggs/g of dried feces; there was no apparent change in fecal egg counts for dogs of the control group. At necropsy, the mean number of adult A caninum in dogs of the treated and control groups was 1.3 and 56, respectively; in these naturally infected dogs, efficacy of treatment was calculated to be 97.8%. The mean number of adult Trichuris vulpis recovered in dogs of the control and treated groups at necropsy was 24 and 0, respectively, which yielded treatment efficacy of 100%. Although Uncinaria stenocephala and Toxocara canis appeared also to be removed by use of this dosage, too few dogs were in the study to calculate meaningful efficacies.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of milbemycin on adult Toxocara canis in dogs with experimentally induced infection

To determine the efficacy of a formulation of milbemycins in treating patent infection with Toxocara canis, 8 male and 7 female, 10-week-old, ascarid-free Beagles each were given 125 embryonated eggs of T canis. All dogs developed patent infection within 56 days. On post-infection day 70, the dogs were assigned to 1 of 3 groups of 5 dogs each; members of 1 group were given a placebo, while dogs of the other 2 groups were given either 5.68 or 34.08 mg of the milbemycin formulation, respectively. In both groups of dogs given the drug, the number of eggs passed per gram of feces decreased precipitously. However, a few eggs still were found in the feces of several dogs of each group on the day of necropsy (postinfection day 75). Worms or fragments of worms were passed by the treated dogs from the day of treatment until the day on which necropsy was performed; however, most worms were passed during the first 2 days after treatment. At necropsy, only dogs of the control group were found to harbor adult T canis.

Effectiveness of a topical antifungal agent (clotrimazole) in dogs

An infection of Trichophyton mentagrophytes was induced in 13 dogs, and of Microsporum canis, in 9 dogs. After the lesions became established, they were assigned to a group for clotrimazole treatment, miconazole treatment, or no treatment. Treatments were applied one daily for 28 days, using a double blind method. The lesions were evaluated by daily scoring of severity and by semiweekly culturing throughout the treatment period. Compared with untreated controls, the response to clotrimazole was significantly better from day 11 until the end of the study. The response to clotrimazole equaled or occasionally exceeded that to miconazole.

Chemical vasectomy in dogs. Long-term study

An effective, non-surgical method of sterilization is needed for controlling growth of the dog population. Intraepididymal injection of 0.5 ml or 1.0 ml of an aqueous solution of 3.0% chlorhexidine digluconate in 50% dimethylsulfoxide (DMSO) given into each tail of the epididymides of dogs resulted in azoospermic ejaculates by days 35 or 42 after treatment. The azoospermia induced by treatment was long-lasting and likely irreversible. Intraepididymal injection of 1.0 ml of an aqueous solution of 4.5% chlorhexidine digluconate, without DMSO, given into each tail of the epididymides of dogs resulted in azoospermic ejaculates by day 28 after treatment, but the permanence of the azoospermia was not determined. The method of intraepididymal injection of sclerosing agents appears safe and suitable for large-scale sterilization programs for controlling dog populations.

Immunotherapy in ocular equine sarcoid

A modified Bacillus Calmette-Guerin (BCG) preparation was used successfully in the treatment of 7 cases of equine sarcoid. The BCG preparation was injected into the lesions. The longest period of remission has been 24 months, and the shortest period of remission has been 9 months, with no signs of recurrence of the tumor in any of the presented cases.