Clinical efficacy and safety of cefovecin in the treatment of canine pyoderma and wound infections

OBJECTIVES: To determine the efficacy and safety of cefovecin in the treatment of bacterial skin infections in dogs. METHOD: Dogs with superficial or deep pyoderma or wounds/abscesses were enrolled in three separate studies. Dogs (354) were randomised to treatment and received either cefovecin administered by subcutaneous injection at 14 day intervals, as clinically necessary, or amoxicillin/clavulanic acid as oral tablets twice daily for 14 days. Courses of treatment were repeated at 14 day intervals up to a total of four courses. Clinicians responsible for assessing lesions were masked to treatment allocation. Only animals where the presence of a pretreatment bacterial pathogen was confirmed were included in the analysis of efficacy. Cases were evaluated for clinical efficacy at 28 days after initiation of the final course of treatment. Clinical efficacy was assessed by scoring the clinical signs typical of skin infections. RESULTS: Cefovecin demonstrated statistical non-inferiority compared with amoxicillin/clavulanic acid for all three clinical diagnoses; for cefovecin, up to 96.9 per cent efficacy was observed versus 92.5 per cent for amoxicillin/clavulanic acid. CLINICAL SIGNIFICANCE: Cefovecin was shown to be as effective as amoxicillin/clavulanic acid administered orally in the treatment of bacterial skin infections in dogs. Cefovecin offers the additional benefit of eliminating owner non-compliance.     

Efficacy and safety of cefovecin for the treatment of urinary tract infections in cats

OBJECTIVES: To determine the efficacy and safety of cefovecin (Convenia); Pfizer Animal Health) in the treatment of urinary tract infections in cats. METHOD: A multi-centre, masked, randomised study was conducted in cats presenting with clinical signs indicative of urinary tract infections. Cephalexin (Rilexine); Virbac) administered orally twice daily at 15 mg/kg bodyweight for 14 days was compared with a single subcutaneous injection of cefovecin in cats. The primary efficacy parameter assessed was bacterial elimination of the pretreatment uropathogen. RESULTS: Four hundred and thirty-four cats were screened for urinary tract infections. One hundred and eighty-five cats were treated with either cefovecin (n=124) or cephalexin (n=61). Ninety-seven cats (22.2 per cent) had confirmed bacteriuria and 82 cats were included in efficacy analysis. Escherichia coli was eliminated in 76.7 per cent (23 of 30) of cefovecin-treated cats compared with 62.5 per cent (10 of 16) of cephalexin-treated cats. Cefovecin demonstrated statistical non-inferiority compared with cephalexin for bacterial elimination. There were no suspected adverse drug reactions attributable to treatment with cefovecin or cephalexin. CLINICAL SIGNIFICANCE: Cefovecin was demonstrated to be an effective and safe treatment for urinary tract infections.     

Estimation of the clinical and economic consequences of non-compliance with antimicrobial treatment of canine skin infections

The goal of this study was to estimate the health and economic consequences of non-compliance with oral antimicrobial treatment in dogs with superficial pyoderma, wounds or abscesses in the US. A mathematical model (Markov model) which simulated treatment with long-term injectable cefovecin versus oral amoxicillin/clavulanic acid was developed and accounted for the effect of non-compliance on clinical outcomes and mean total treatment costs per patient. Efficacy parameters considered in the model were derived from clinical studies. Treatment failure due to oral antimicrobial treatment non-compliance was approximated from published data at 13.6%. US cost data for 2009 were derived from public sources. When non-compliance was considered as a cause of treatment failure with oral medication, the long-term injectable antibiotic was more effective than oral comparator (162 versus 158 days without clinical signs). Mean total treatment costs were lower with cefovecin (USD 376.74) versus amoxicillin/clavulanic acid (USD 382.34) in dogs of 25 kg; and cefovecin remained cost-saving up to a body weight of 31 kg. In large dogs, cefovecin was more costly; however, total therapy costs were less than 6% greater than with amoxicillin/clavulanic acid. Accordingly the higher drug and administration costs of the long-term injectable antibiotic were totally or substantially offset when non-compliance was considered as reason for treatment failure with oral medication. The model also allowed for the estimation of the impact of various non-compliance scenarios.     

Single subcutaneous dosing of cefovecin in rhesus monkeys (Macaca mulatta): a pharmacokinetic study

Bakker, J., Thuesen, L. R., Braskamp, G., Skaanild, M. T., Ouwerling, B., Langermans, J. A. M., Bertelsen, M. F. Single subcutaneous dosing of cefovecin in rhesus monkeys (Macaca mulatta): a pharmacokinetic study. J. vet. Pharmacol. Therap. 34 , 464–468. Cefovecin is a third‐generation cephalosporin approved for antibacterial treatment with a 14‐day dosing interval in dogs and cats. This antibiotic may also be useful for zoo and wildlife veterinary medicine, because of its broad spectrum and long duration of activity. The aim of the study was to determine whether cefovecin is a suitable antibiotic to prevent skin wound infection in rhesus monkeys. Therefore, the pharmacokinetics (PK) of cefovecin after a single subcutaneous injection at 8 mg/kg bodyweight in four rhesus monkeys (Macaca mulatta) and sensitivity of bacterial isolates from fresh skin wounds were determined. After administration, blood, urine, and feces were collected, and concentrations of cefovecin were determined. Further, the minimum inhibitory concentrations (MIC) for bacteria isolated from fresh skin wounds of monkeys during a health control program were determined. The mean maximum plasma concentration (C_max) of cefovecin was 78 μg/mL and was achieved after 57 min. The mean apparent long elimination half‐life (t½) was 6.6 h and excretion occurred mainly via urine. The MIC for the majority of the bacteria examined was >100 μg/mL. The PK of cefovecin in rhesus monkeys is substantially different than for dogs and cats. Cefovecin rapidly reached C_max which however was lower than most of the MIC levels and with a very short t½. Therefore, cefovecin is not recommended for treating skin wounds in rhesus monkeys.     

Efficacy and safety of cefovecin in treating bacterial folliculitis, abscesses, or infected wounds in dogs

OBJECTIVE: To evaluate the efficacy and safety of administration of cefovecin, compared with cefadroxil, for treatment of naturally occurring secondary superficial pyoderma, abscesses, and infected wounds in dogs. DESIGN: Multicenter, randomized, positive-controlled clinical trial. ANIMALS: 235 client-owned dogs. PROCEDURES: Dogs with clinical signs of skin infection confirmed via bacteriologic culture were randomly allocated to receive a single SC injection of cefovecin (8 mg/kg [3.6 mg/lb]) followed by placebo administered PO twice daily for 14 days or cefadroxil (22 mg/kg [10 mg/lb]) administered PO twice daily for 14 days following a placebo injection. Two 14-day treatment courses were permitted. Treatment success was defined as reduction of clinical signs to mild or absent at the final assessment. RESULTS: Clinical efficacy achieved with cefovecin in dogs was equivalent to that observed with cefadroxil. At the final assessment, 14 days following the completion of treatment (on day 28 or 42), 92.4% (109/118) of the cefovecin group and 92.3% (108/117) of the cefadroxil group were treatment successes. There were no serious adverse events or deaths related to treatment. CONCLUSIONS AND CLINICAL RELEVANCE: A single cefovecin injection (8 mg/kg) administered SC, which could be repeated once after 14 days, was safe and effective against naturally occurring skin infections in dogs and as effective as cefadroxil administered PO twice daily for 14 or 28 days.     

Efficacy and safety of cefovecin (Convenia) for the treatment of urinary tract infections in dogs

OBJECTIVES: To determine the efficacy and safety of cefovecin (Convenia); Pfizer Animal Health) in the treatment of urinary tract infections in dogs. METHODS: A multi-centre, blinded, randomised study was conducted in 129 dogs with urinary tract infections. Cephalexin (Rilexine) administered twice daily at 15 mg/kg bodyweight orally for 14 days was compared with a single, subcutaneous injection of cefovecin (Convenia) in dogs. The primary efficacy parameter assessed was bacterial elimination of the pretreatment uropathogen. RESULTS: One hundred and twenty-nine dogs were included in efficacy assessments. Escherichia coli was eliminated in 90.5 per cent of cefovecin-treated dogs compared with 52.9 per cent of cephalexin-treated dogs (P=0.0004). Overall cure rates for dogs with Escherichia coli infections were 79.1 per cent for cefovecin and 36.4 per cent for cephalexin-treated dogs (P=0.0003). There were no suspected adverse drug reactions attributed to treatment with cefovecin or cephalexin. CLINICAL SIGNIFICANCE: Cefovecin was shown to be an effective and safe treatment for urinary tract infections.     

Pharmacokinetics of intravenous and subcutaneous cefovecin in alpacas

The purpose of this study was to determine the pharmacokinetics of cefovecin after intravenous and subcutaneous dose of 8 mg/kg to alpacas. Bacterial infections requiring long‐term antibiotic therapy such as neonatal bacteremia, pneumonia, peritonitis, dental, and uterine infections are a significant cause of morbidity and mortality in this species. However, few antimicrobials have been evaluated and proven to have favorable pharmacokinetics for therapeutic use. Most antimicrobials that are currently used require daily injections for many days. Cefovecin is a long‐acting cephalosporin that is formulated for subcutaneous administration, and its long‐elimination half‐life allows for 14‐day dosing intervals in dogs and cats. The properties of cefovecin may be advantageous for medical treatment of camelids due to its broad spectrum, route of administration, and long duration of activity. Pharmacokinetic evaluation of antimicrobial drugs in camelids is essential for the proper treatment and prevention of bacterial disease, and to minimize development of antibiotic resistant bacterial strains due to inadequate antibiotic concentrations. Cefovecin mean half‐life, volume of distribution at steady‐state, and clearance after intravenous administration were 10.3 h, 86 mL/kg, and 7.07 mL·h/kg. The bioavailability was 143%, while half‐life, C_max, and T_max were 16.9 h, 108 μg/mL, and 2.8 h following subcutaneous administration. In the absence of additional microbial susceptibility data for alpaca pathogens, the current cefovecin dosage regimen prescribed for dogs (8 mg/kg SC every 14 days) may need to be optimized for the treatment of infections in this species.     

Feline bacterial urinary tract infections: An update on an evolving clinical problem

Although feline urine is increasingly submitted for bacterial culture and susceptibility testing as part of a more general diagnostic work-up for a range of presentations in veterinary practice, bacterial urinary tract infections (UTIs) are relatively uncommon due to a variety of physical and immunological barriers to infection. Culture positive urine is most often obtained from older female cats and the clinical history may include hematuria, dysuria and pollakiuria, or the infection may be occult. Urinalysis usually reveals hematuria and pyuria, and Escherichia coli and Gram-positive cocci are cultured most frequently. Most feline UTIs can be successfully treated using oral amoxicillin or amoxicillin/clavulanic acid administered for at least 14 days, but the prevalence of antimicrobial resistance amongst infecting bacterial species is a growing concern. There is currently no conclusive information on the safety and efficacy of alternative therapeutic agents for the treatment of feline UTIs.     

Clinical and in vitro efficacy of amoxicillin against bacteria associated with feline skin wounds and abscesses

A clinical trial involving 122 cats with infected skin wounds or abscesses presented to 10 veterinary clinics was conducted to evaluate the efficacy of 2 oral amoxicillin drug products (a paste and a suspension). A 2nd objective of the study was to identify bacteria involved in such infections and verify their in vitro sensitivity to amoxicillin. Samples of wound exudate were harvested at the time of presentation and submitted for aerobic and anaerobic culture. The sensitivity to amoxicillin of isolates thought to be infecting agents was tested, using a standard minimum inhibitory concentration method. Pasteuralla multocida and obligate anaerobes of the genera Prevotella, Fusobacterium, and Porphyromonas were the most frequently isolated pathogens. Overall, their in vitro susceptibility to amoxicillin was very good. Both drug products were clinically efficacious with a global success rate of 95.1% for cats administered oral amoxicillin at 11-22 mg/kg bodyweight (mean 13.8 mg/kg bodyweight) twice daily for 7 to 10 days.     

Selected pharmacokinetic parameters for Cefovecin in hens and green iguanas

The third generation cephalosporin cefovecin has been shown to have an exceptionally long elimination half-life in dogs and cats, making it suitable for antibacterial treatment with a 14-day dosing interval in these species. Pharmacokinetic parameters for cefovecin were investigated in juvenile hens and green iguanas, following subcutaneous injections with 10 mg cefovecin/kg bodyweight. Preliminary studies in eight additional species of birds and reptiles were performed and results were compared with the parameters found in hens and green iguanas. The kinetics were characterized by rapid absorption with peak plasma concentration of 6 ± 2 μg/mL in hens and 35 ± 12 μg/mL in green iguanas. The mean plasma half-life for cefovecin was 0.9 ± 0.3 h for hens and 3.9 h in green iguanas. Volume of distribution was 1.6 ± 0.5 L/kg for hens and 0.3 L/kg for green iguanas and clearance was 1252 ± 185 mL·h/kg for hens and 53 mL·h/kg for green iguanas. Results from preliminary studies did not differ notably from those seen in hens and green iguanas. Cefovecin is not suitable for the treatment of bacterial infections with a 14-day dosing interval in hens or green iguanas and seems not to be in a number of other bird and retile species either.     

The effectiveness of systemic antimicrobial treatment in canine superficial and deep pyoderma: a systematic review

Aim – To identify and evaluate existing evidence for the effectiveness of systemic antimicrobial treatments for naturally occurring superficial and deep canine pyoderma. Method – Electronic searches of PubMed, MEDLINE and CAB Direct were carried out (25 May 2011) without date or language restrictions. Proceedings of ESVD/ECVD, AAVD/ACVD, NAVDF and WCVD annual congresses were searched. Unpublished studies were sought via the Veterinary Dermatology discussion list and Veterinary Information Network. Results – Seventeen full‐length, peer‐reviewed controlled trials reporting clinical outcomes of systemic antimicrobial treatment for canine pyoderma were identified. Outcomes specific to superficial or deep pyoderma were reported in nine and five studies, respectively. Five studies reported outcomes only for nondifferentiated pyoderma depth. Heterogeneity of study designs and outcome measures made meta‐analysis inappropriate. A good level of evidence was identified supporting the high efficacy of subcutaneously injected cefovecin in superficial pyoderma and for oral amoxicillin–clavulanic acid in deep pyoderma. A fair level of evidence was identified for moderate to high efficacy of oral amoxicillin–clavulanic acid, clindamycin, cefadroxil, trimethoprim–sulphamethoxazole and sulfadimethoxine–ormetoprim in superficial pyoderma and oral pradofloxacin, oral cefadroxil and subcutaneously injected cefovecin in deep pyoderma. Eleven trials reported observations of adverse effects in treated pyoderma cases by intervention group; four dogs were withdrawn owing to the severity of adverse effects. Conclusions – There is a need for greater numbers of adequately sized, blinded, randomized controlled trials evaluating systemic antimicrobial interventions for canine pyoderma. Improved differentiation between superficial and deep pyoderma in outcome reporting, outcome measure standardization and association of outcomes with causative bacterial species and their resistance patterns are required.     

Seroprevalences of feline leukemia virus and feline immunodeficiency virus in cats with abscesses or bite wounds and rate of veterinarian compliance with current guidelines for retrovirus testing

OBJECTIVE: To determine the seroprevalences of and seroconversion rates for FeLV and FIV infection in cats treated for bite wounds and cutaneous abscesses and to evaluate compliance with recommendations to determine the retrovirus infection status of cats at acquisition and 60 days after a high-risk event. DESIGN: Prospective study. ANIMALS: 967 cats from 134 veterinary practices in 30 states. PROCEDURES: Cats with bite wounds or abscesses were evaluated by use of a point-of-care immunoassay for blood-borne FeLV antigen and FIV antibody. Veterinarians were asked to retest cats approximately 60 days later to determine whether seronegative cats had seroconverted after injury. RESULTS: The combined FeLV-FIV status of only 96 (9.9%) cats was known prior to wound treatment. At the time of treatment, 187 (19.3%) cats were seropositive for 1 or both viruses. Age (adult), sex (male), history of cutaneous wounds, and outdoor access were significantly associated with seropositivity. At 73 of 134 (54.5%) veterinary practices, retesting of cats for retrovirus infection status was recommended to owners of 478 cats. Only 64 (13.4%) cats were retested; of these, 3 of 58 (5.2%) cats that were initially seronegative for FIV antibody seroconverted. CONCLUSIONS AND CLINICAL RELEVANCE: A high proportion of cats with abscesses or bite wounds were seropositive for FeLV antigen or FIV antibody. Compliance with recommendations to test cats for retrovirus infection status at acquisition or after treatment for injury was low. The FeLV-FIV infection status of cats with potential fight wounds should be determined at time of treatment and again 60 days later.     

Differential activity of cythioate against female and male Ctenocephalides felis on cats.

A study was conducted to determine whether cythioate, a systemically active insecticide, has different activity against male and female Ctenocephalides felis, the cat flea. Eighteen cats were allotted equally to 1 control and 2 treatment groups and infested on day 0 with fixed ratios of male and female cat fleas. Cats in the untreated control group and treatment group 2 were infested with 50 fleas with a female-to-male ratio of approximately 2:1. Cats in treatment group 1 were infested with 50 fleas with a female-to-male ratio of 1:1. Cythioate was administered orally to cats in the treatment groups at the dosage of 3.6 mg/kg of body weight once daily on days 0 and 3. Fleas remaining after treatment were removed, sexed, and counted on day 5. The efficacy of cythioate after 2 dosings was 82.8 and 33.4% against female and male fleas, respectively. The greater activity against female fleas resulted in post-treatment female-to-male ratios in treatment groups 1 and 2 of 0.32:1 and 0.54:1, respectively. Fleas recovered from untreated control cats had a final female-to-male ratio of 2.27:1. Total population control efficacies for treatment groups 1 and 2 were 61.7 and 67.6%, respectively.     

Cutaneous wound healing in the cat: a macroscopic description and comparison with cutaneous wound healing in the dog

OBJECTIVE: To describe the macroscopic features of first and second intention cutaneous wound healing in the cat and compare with the dog. STUDY DESIGN: Experimental study. ANIMALS: Domestic shorthaired cats (6) and beagle dogs (6). METHODS: Square, open cutaneous wounds created on the dorsal aspect of the thorax were evaluated for 21 days for temporal and spatial development of granulation tissue, wound contraction, epithelialization, and total healing. To evaluate first intention healing, breaking strength of sutured linear cutaneous wounds was measured at 7 days post-wounding. Laser-Doppler perfusion imaging was used to measure cutaneous perfusion. RESULTS: First intention healing: sutured wounds in cats were only half as strong as those in dogs at day 7 (0.406 versus 0.818 kg breaking strength). Second intention healing: cats produced significantly less granulation tissue than dogs, with a peripheral, rather than central distribution. Wound epithelialization and total wound healing (total reduction in open wound area from contraction and epithelialization) were greater for dogs than for cats over 21 days. Wound contraction on day 7 was greater for dogs, but not on day 14 or 21. Cutaneous perfusion was initially greater for dogs than for cats, but no differences were detected after day 7. CONCLUSIONS: Significant, previously unreported differences in cutaneous wound healing exist between cats and dogs. In general, cutaneous wounds in cats are slower to heal. Cats and dogs also appear to use different mechanisms of second intention healing. In cats wounds close mainly by contraction of the wound edges, whereas in dogs wounds close more from central pull, and epithelialization. CLINICAL RELEVANCE: Surgeons should view the cat as a unique species, which presents its own special challenges in wound healing, and should take this into account when planning treatment of feline wounds, either by primary closure, or by second intention healing.     

Tracheal rupture associated with intubation in cats: 20 cases (1996-1998)

OBJECTIVE: To characterize clinical features of tracheal rupture associated with endotracheal intubation in cats and to evaluate the most appropriate treatment for this condition. DESIGN: Retrospective study. ANIMALS: 20 cats with a history of endotracheal intubation that subsequently developed dyspnea or subcutaneous emphysema. PROCEDURE: Medical records of cats with a presumptive diagnosis of tracheal rupture associated with intubation were reviewed. Clinical and clinicopathologic data were retrieved. RESULTS: Cats were evaluated 5 hours to 12 days after a surgical or medical procedure requiring general anesthesia with intubation had been performed. Fourteen (70%) cats were evaluated after dental prophylaxis. All cats radiographed had pneumomediastinum and subcutaneous emphysema. Eighteen of 19 cats were initially treated medically. Duration of medical treatment for cats that did not have surgery ranged from 12 to 72 hours. Cats that had surgery received medical treatment 3 to 24 hours prior to the surgical procedure. Medical treatment alone was administered to 15 cats that had moderate dyspnea, whereas surgical treatment was chosen for 4 cats that had severe dyspnea (open-mouth breathing despite treatment with oxygen) or worsening subcutaneous emphysema. Eighteen cats had improvement of clinical signs, 1 cat died after surgery, and 1 cat died before medical or surgical intervention. CONCLUSIONS AND CLINICAL RELEVANCE: Most cats with tracheal rupture associated with intubation can be treated medically. Cats with worsening clinical signs (severe dyspnea, suspected pneumothorax, or worsening subcutaneous emphysema) should have surgery performed immediately to correct the defect.     

Feline interferon response to 2-amino-5-bromo-6-methyl-4-pyrimidinol (U-25,166)

U-25,166 induced high serum interferon levels in cats at concentrations at least 40 times less than the maximum tolerated dose. Although certain cats responded to U-25,166 by consistently producing higher interferon levels than did other cats, this relationship was not observed if the same animals were injected with Newcastle disease virus or polyriboinosinic:polyribocytidylic acid (poly I:C). Using a biweekly treatment regimen, cats remained responsive to interferon induction by U-25,166 over an 18-week period in which 9 doses of the compound were given. Cats given the compound daily, however, soon became hyporesponsive to interferon induction. Interferon was induced in cats given U-25,166 orally as a suspension or in capsules, but circulating interferon levels were low in cats given the drug by subcutaneous injection.     

Sedative and physiologic effects of orally administered alpha 2-adrenoceptor agonists and ketamine in cats

OBJECTIVE: To compare efficacy of 3 regimens of orally administered sedatives and determine physiologic effects of 1 of these regimens in healthy cats. DESIGN: Prospective randomized study. ANIMALS: 34 cats. PROCEDURE: Cats were assigned to 1 of 3 groups that were treated by oral administration of detomidine and ketamine, xylazine and ketamine, or medetomidine and ketamine. Cats were monitored for degree of sedation at 5-minute intervals for 60 minutes. Physiologic effects in cats treated with detomidine and ketamine were measured at 5-minute intervals for 30 minutes and compared with effects in cats treated i.m. with detomidine and ketamine or xylazine and ketamine. RESULTS: All cats treated orally with detomidine and ketamine became laterally recumbent; sedation was more variable in the other 2 groups treated orally. Vomiting and excessive salivation were the only adverse effects. Bradycardia (heart rate < 145 beats/min) was detected at each evaluation time in cats treated orally with detomidine and ketamine and in all cats treated i.m. Minimal differences among groups were detected for heart and respiratory rates, rectal temperature, and hemoglobin oxygen saturation. CONCLUSIONS AND CLINICAL RELEVANCE: Oral administration of detomidine and ketamine is an effective method of sedating healthy cats and induces minimal physiologic effects that are similar to those resulting from i.m. administration of sedatives.     

Pharmacokinetics and pharmacodynamics of cefovecin in dogs

A series of in vivo, ex vivo and in vitro studies were conducted to determine the pharmacokinetic and pharmacodynamic properties of cefovecin, a new injectable cephalosporin, in dogs. Absolute bioavailability was determined in a two-phase cross-over study in dogs receiving 8 mg/kg bodyweight (b.w.) of cefovecin by either subcutaneous (s.c.) or intravenous (i.v.) route. After s.c. administration, cefovecin was fully bioavailable (100%), the mean maximum plasma concentration (Cmax) was 121 microg/mL and the mean apparent elimination half-life (t1/2) was 133 h. Clearance was measured to be 0.76 mL/h/kg after i.v. dosing. The concentration of cefovecin in urine measured 14 days after s.c. administration was 2.9 microg/mL. Plasma protein binding was determined by equilibrium dialysis; over concentrations ranging from 10 to 100 microg/mL (i.e. up to the approximate Cmax following an 8 mg/kg dose), protein binding of 98.7% to 96.0% was observed, however, binding was lower at higher concentrations. Total and free concentrations of cefovecin were determined in plasma, transudate and exudate collected from dogs previously implanted subcutaneously with tissue cages. Mean peak concentrations of free cefovecin were almost three times higher in transudate than in plasma and remained above 0.25 microg/mL for 19 days. The ex vivo antibacterial killing activity (vs. Staphylococcus intermedius, MIC 0.25 microg/mL) was measured in serum, transudate and exudate collected from dogs which had received 8 mg/kg b.w. of cefovecin subcutaneously. Transudate exhibited higher antimicrobial killing activity than serum. Activity in serum and exudate exhibited a mean reduction in bacterial counts of S. intermedius of at least three log units up to 72 h postadministration. Bactericidal activity (>3 log10 reduction of bacterial counts) was observed in transudate up to 12 days postadministration. The slow elimination and long lasting ex vivo antibacterial killing activity following administration of cefovecin are desirable pharmacokinetic and pharmacodynamic attributes for an antimicrobial drug with 14-day dosing intervals.     

Usefulness of cefovecin disk‐diffusion test for predicting mecA gene‐containing strains of Staphylococcus pseudintermedius and clinical efficacy of cefovecin in dogs with superficial pyoderma

Background –  Cefovecin has been widely used to treat skin infections in dogs. The relationship of the cefovecin disk‐diffusion test results to the presence of the mecA gene and the clinical efficacy of cefovecin have not been fully evaluated. Hypothesis/Objectives –  To determine the usefulness of an in vitro cefovecin disk‐diffusion test in predicting the presence of the mecA gene in Staphylococcus pseudintermedius, as well as the in vivo efficacy of cefovecin therapy in dogs with superficial pyoderma. Methods –  Twenty‐six S. pseudintermedius strains isolated from 22 dogs with pyoderma were used. In vitro disk‐diffusion test results of cefovecin were compared with agar‐dilution test results, the presence of the mecA gene, and the improvement in clinical scores of dogs with superficial pyoderma at 14 days post treatment. Results –  There was a significant linear correlation (r = ?0.83) between the diameter of the obvious zone of inhibition by disk diffusion and the minimal inhibitory concentration for cefovecin (P < 0.0001). Receiver operating characteristic analysis revealed that zone diameters between 25 and 27 mm exhibited better sensitivity (92.9%) and specificity (100.0%) for detection of strains carrying the mecA gene. The mean improvement in clinical scores in dogs carrying cefovecin‐resistant strains was significantly lower than in dogs carrying cefovecin‐susceptible strains (P < 0.01). Conclusions and clinical importance –  The cefovecin disk‐diffusion test with a cut‐off value estimated in this study was valuable for predicting mecA gene carriage in S. pseudintermedius, as well as the in vivo efficacy of cefovecin therapy in dogs with superficial pyoderma caused by S. pseudintermedius.     

Quantitative analysis of microfilarial periodicity of Dirofilaria immitis in cats

Microfilarial periodicity of Dirofilaria immitis in the venous blood of infected cats was analyzed by a trigonometric model. Cats were infected by subcutaneous transplantation with 120-day-old juvenile D. immitis. Microfilariae in the blood were first observed 98 days after transplantation. Blood was collected at 4h intervals for a 24h period, and examinations were repeated five times in two cats. The calculated periodicity index was 75.1 and 50.3 in these two cats. The estimated hour of peak microfilarial density ranged from 1.00 to 2.84h. Thus, the periodicity of microfilariae of D. immitis in the blood of cats was characterized as nocturnally sub-periodic.