Activity of an injectable, sustained-release formulation of moxidectin administered prophylactically to mixed-breed dogs to prevent infection with Dirofilaria immitis

James B. Lok Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104.

Search for other papers by James B. Lok in
Current site
Google Scholar
PubMed
Close
 PhD
,
David H. Knight Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104.

Search for other papers by David H. Knight in
Current site
Google Scholar
PubMed
Close
 DVM, MMEdSc
,
G. T. Wang Fort Dodge Animal Health, Cyanamid Research Agricultural Research Center, Clarkesville and Quakerbridge Rds, Princeton, NJ 08543.

Search for other papers by G. T. Wang in
Current site
Google Scholar
PubMed
Close
 DVM, PhD
,
Mary E. Doscher Fort Dodge Animal Health, Cyanamid Research Agricultural Research Center, Clarkesville and Quakerbridge Rds, Princeton, NJ 08543.

Search for other papers by Mary E. Doscher in
Current site
Google Scholar
PubMed
Close
 MS
,
Thomas J. Nolan Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104.

Search for other papers by Thomas J. Nolan in
Current site
Google Scholar
PubMed
Close
 PhD
,
Mattie J. Hendrick Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104.

Search for other papers by Mattie J. Hendrick in
Current site
Google Scholar
PubMed
Close
 VMD
,
William Steber Fort Dodge Animal Health, Cyanamid Research Agricultural Research Center, Clarkesville and Quakerbridge Rds, Princeton, NJ 08543.

Search for other papers by William Steber in
Current site
Google Scholar
PubMed
Close
 MS
, and
Kathleen Heaney Fort Dodge Animal Health, Cyanamid Research Agricultural Research Center, Clarkesville and Quakerbridge Rds, Princeton, NJ 08543.

Search for other papers by Kathleen Heaney in
Current site
Google Scholar
PubMed
Close
 DVM

Abstract

Objective—To test the ability of a single injection of a sustained-release formulation of moxidectin (moxidectin SR) to protect dogs against heartworm infection for 180 days after inoculation with infective thirdstage larvae (L3) of Dirofilaria immitis.

Animals—32 adult mixed-breed dogs.

Procedure—Dogs were allocated to 4 groups on the basis of weight and sex. Dogs were injected SC with saline (0.9% NaCl) solution or moxidectin SR at the rate of 0.06, 0.17, or 0.5 mg/kg of body weight (day 0). Each dog was inoculated SC with 50 D immitis L3 180 days later. On days 330 and 331, dogs were euthanatized. The heart, lungs, and thoracic cavity were examined, and number and sex of heartworms were determined.

Results—A mean of 35.9 heartworms was recovered from untreated control dogs. Fourteen worms were recovered from 1 of 8 dogs given moxidectin SR at the lowest dosage, and none of the dogs in the 2 highest moxidectin treatment groups were infected. Small barely palpable granulomas were detected at injection sites of moxidectin-treated dogs. Frequency and size of granulomas were positively correlated with dose of moxidectin administered.

Conclusions and Clinical Relevance—A single dose of moxidectin SR at a dosage as low as 0.17 mg/kg can safely and reliably confer complete protection against infection after challenge-exposure with D immitis L3, and protection lasts for at least 180 days. This mode of prophylactic treatment against infection with heartworms effectively eliminates failure of prophylaxis that results from erratic administration of medications designed for monthly administration. (Am J Vet Res 2001;62:1721–1726)

Abstract

Objective—To test the ability of a single injection of a sustained-release formulation of moxidectin (moxidectin SR) to protect dogs against heartworm infection for 180 days after inoculation with infective thirdstage larvae (L3) of Dirofilaria immitis.

Animals—32 adult mixed-breed dogs.

Procedure—Dogs were allocated to 4 groups on the basis of weight and sex. Dogs were injected SC with saline (0.9% NaCl) solution or moxidectin SR at the rate of 0.06, 0.17, or 0.5 mg/kg of body weight (day 0). Each dog was inoculated SC with 50 D immitis L3 180 days later. On days 330 and 331, dogs were euthanatized. The heart, lungs, and thoracic cavity were examined, and number and sex of heartworms were determined.

Results—A mean of 35.9 heartworms was recovered from untreated control dogs. Fourteen worms were recovered from 1 of 8 dogs given moxidectin SR at the lowest dosage, and none of the dogs in the 2 highest moxidectin treatment groups were infected. Small barely palpable granulomas were detected at injection sites of moxidectin-treated dogs. Frequency and size of granulomas were positively correlated with dose of moxidectin administered.

Conclusions and Clinical Relevance—A single dose of moxidectin SR at a dosage as low as 0.17 mg/kg can safely and reliably confer complete protection against infection after challenge-exposure with D immitis L3, and protection lasts for at least 180 days. This mode of prophylactic treatment against infection with heartworms effectively eliminates failure of prophylaxis that results from erratic administration of medications designed for monthly administration. (Am J Vet Res 2001;62:1721–1726)

All Time Past Year Past 30 Days
Abstract Views 41 0 0
Full Text Views 2431 2202 108
PDF Downloads 253 111 9
Advertisement