Nasal cavity dimensions in guinea pig and rat measured by acoustic rhinometry and fluid-displacement method.

The purpose of the study was to measure nasal passageway dimensions in guinea pigs and rats by use of acoustic rhinometry (AR) and by a previously described fluid-displacement method (FDM) (Straszek SP, Taagehoej F, Graff S, and Pedersen OF. J Appl Physiol 95: 635-642, 2003) to investigate the potential of AR in pharmacological research with these animals. We measured the area-distance relationships by AR of nasal cavities postmortem in five guinea pigs (Duncan Hartley, 400 g) and five rats (Wistar, 250 g) by using custom-made equipment scaled for the purpose. Nosepieces were made from plastic pipette tips and either inserted into or glued onto the nostrils. We used liquid perfluorocarbon in the fluid-displacement study, and it was carried out subsequent to the acoustic measurements. We found for guinea pigs that AR measured a mean volume of 98 mm(3) (95-100 mm(3)) (mean and 95% confidence interval) of the first 2 cm of the cavity. FDM measured a mean volume of 146 mm(3) (117-175 mm(3)), meaning that AR only measured 70% (50-90) of the volume by FDM. For rats, the volume from 0 to 2 cm was 58 mm(3) (55-61 mm(3)) by AR and 73 mm(3) (60-87 mm(3)) by FDM, resulting in AR only measuring 83% (66-100%) of volume by FDM (see Table 2). We conclude that absolute nasal cavity dimensions are underestimated by AR in guinea pigs and rats. This does not preclude that relative changes may be correctly measured. In vivo trials with AR using rats have not yet been published. The FDM is possibly the most accurate alternative to AR for measurements of the nasal cavity geometry in small laboratory animals, but it can only be used postmortem.     

A Simplified Geometric Model to Predict Nasal Spray Deposition in Children and Adults

A mathematical approach was developed to estimate spray deposition patterns in the nasal cavity based on the geometric relationships between the emitted spray plume and the anatomical dimensions of the nasal valve region of the nasal cavity. Spray plumes were assumed to be spherical cones and the nasal valve region was approximated as an ellipse. The effect of spray plume angle (15–85°) on the fraction of the spray able to pass through the nasal valve (deposition fraction) was tested for a variety of nasal valve (ellipse) shapes and cross-sectional areas based on measured dimensions from pediatric and adult nasal cavities. The effect of the distances between the tip of the nasal spray device and the nasal valve (0.2–1.9 cm) on the deposition fraction was also tested. Simulation results show that (1) decreasing spray plume angles resulted in higher deposition fractions, (2) deposition fraction was inversely proportional to the spray distance and the nasal valve (ellipse) major/minor axis ratio, and (3) for fixed major/minor axis ratios, improved deposition occurred with larger nasal valve cross-sectional areas. For a typical adult nasal valve, plume angles of less than 40° emitted from a distance of 1 cm resulted depositions greater than 90% within the main nasal cavity, whereas for a 12-year-old child, only the most narrow plume angles (<?20°) administered resulted in significant deposition beyond the nasal valve.     

Effects of the nasal valve on acoustic rhinometry measurements: a model study.

The influence of nasal valve on acoustic rhinometry (AR) measurements was evaluated by using simple nasal cavity models. Each model consisted of a cylindrical pipe with an insert simulating the nasal valve. The AR-determined cross-sectional areas beyond the insert were consistently underestimated, and the corresponding area-distance curves showed pronounced oscillations. The area underestimation was more pronounced in models with inserts of small passage area. The experimental results are discussed in terms of theoretically calculated "sound-power reflection coefficients" for the pipe models. The reason for area underestimation is reflection of most of the incident sound power from the barrier at the front junction between the pipe and the insert. It was also demonstrated that the oscillations are due to low-frequency acoustic resonances in the portion of the pipe beyond the insert. The results suggest that AR does not provide reliable information about the cross-sectional areas of the nasal cavity posterior to a significant constriction, such as pathologies narrowing the nasal valve area. When the passage area of the nasal valve is decreased, the role of AR as a diagnostic tool for the entire nasal cavity becomes limited.     

Acoustic rhinometry: validation by three-dimensionally reconstructed computer tomographic scans.

The aim of the present study was a validation of acoustic rhinometry (AR) by computed tomography (CT). Six healthy subjects were examined by CT and AR. The CT data were processed in a computer program (AutoCAD), and a virtual three-dimensional model of each nasal cavity was constructed. This model permitted an individual prediction of the center line of the sound wave propagation through the air volume of the nasal cavity with the cross-sectional areas oriented perpendicularly to this line. The area-distance curves derived from AR and CT were compared. Linear regression analysis revealed a reasonable agreement of AR and CT in the anterior nose below a mean of 6 cm distance from the nostrils [r = 0.839, P < 0.01, m = 1.123, b = -0.113 (AR = m x CT + b)]. The measuring accuracy using CT as gold standard revealed a mean error at the nasal valve of <0.01 cm(2) (4.52%) and at the nasal isthmus of 0.02 cm(2) (1. 87%). Beyond 6 cm, the correlation decreased (r = 0.419), and overestimation of the true area occurred (>100%). In conclusion, the measurements were reasonably accurate for diagnostic use up to the turbinate head region. Certain factors induce an overestimation of the true areas beyond this region. However, these factors are constant and reproducible in a single subject, and intraindividual comparative measurements are possible beyond the turbinate head region.     

Acoustic rhinometry in humans: accuracy of nasal passage area estimates, and ability to quantify paranasal sinus volume and ostium size.

A comprehensive study that compared acoustic rhinometry (AR) data to computed tomography (CT) data was performed to evaluate the accuracy of AR measurements in estimating nasal passage area and to assess its ability of quantifying paranasal sinus volume and ostium size in live humans. Twenty nasal passages of 10 healthy adults were examined by using AR and CT. Actual cross-sectional areas of the nasal cavity, sinus ostia sizes, and maxillary and frontal sinus volumes were determined from CT sections perpendicular to the curved acoustic axis of the nasal passage. Nasal cavity volume (from nostril to choana) calculated from the AR-derived area-distance curve was compared with that from the CT-derived area-distance curve. AR measurements were also done on pipe models that featured a side branch (Helmholtz resonator of constant volume but two different neck diameters) simulating a paranasal sinus. In the anterior nasal cavity, there was good agreement between the cross-sectional areas determined by AR and CT. However, posterior to the sinus ostia, AR overestimated cross-sectional area. The difference between AR nasal volume and CT nasal volume was much smaller than the combined volume of the maxillary and frontal sinuses. The results suggest that AR measurements of the healthy adult nasal cavity are reasonably accurate to the level of the paranasal sinus ostia. Beyond this point, AR overestimates cross-sectional area and provides no quantitative data for sinus volume or ostium size. The effects of paranasal sinuses and acoustic resonances in the nasal cavity are not accounted for in the present AR algorithms.     

Effects of paranasal sinus ostia and volume on acoustic rhinometry measurements: a model study.

We used pipe models to investigate the effects of paranasal sinus ostium size and paranasal sinus volume on the area-distance curves derived by acoustic rhinometry (AR). Each model had a Helmholtz resonator or a short neck as a side branch that simulated the paranasal sinus and sinus ostium. The AR-derived cross-sectional areas posterior to the ostium were significantly overestimated. Sinus volume affected the AR measurements only when the sinus was connected via a relatively large ostium. The experimental area-distance curve posterior to the side branch showed pronounced oscillations in association with low-frequency acoustic resonances in this distal part of the pipe. The experimental results are discussed in terms of theoretically calculated "sound-power reflection coefficients" for the pipe models used. The results indicate that the effects of paranasal sinuses and low-frequency acoustic resonances in the posterior part of the nasal cavity are not accounted for in the current AR algorithms. AR does not provide reliable information about sinus ostium size, sinus volume, or cross-sectional area in the distal parts of nasal cavity.     

A new nasal acoustic reflection technique to estimate pharyngeal cross-sectional area during sleep.

The conventional acoustic reflection technique in which acoustic waves are launched through the mouth cannot be applied during sleep, nor can it be applied to the nasopharynx, which is the major site of occlusion in patients with obstructive sleep apnea syndrome. We propose a new technique of nasal acoustic reflection to measure pharyngeal cross-sectional areas including the nasopharynx. The acoustic waves are introduced simultaneously to both nostrils during spontaneous nasal breathing. A new algorithm takes into account the nasal septum with asymmetric nasal cavities on both sides and assumes prior knowledge of the cross-sectional area of the nasal cavities and the position of the nasal septum. This method was tested on an airway model with a septum and on healthy human subjects. The conventional technique gave inaccurate measurements for pharyngeal cross-sectional areas for an airway model with asymmetric branching, whereas the new technique measured them almost perfectly. The oro- and hypopharyngeal cross-sectional area measurements acquired by the new method were not different from those obtained by the conventional method in normal subjects. This new method can be used as a monitor of upper airway dimensions in nocturnal polysomnography.     

Measurement of nasal patency in anesthetized and conscious dogs.

Experiments were undertaken to characterize a noninvasive chronic, model of nasal congestion in which nasal patency is measured using acoustic rhinometry. Compound 48/80 was administered intranasally to elicit nasal congestion in five beagle dogs either by syringe (0.5 ml) in thiopental sodium-anesthetized animals or as a mist (0.25 ml) in the same animals in the conscious state. Effects of mast cell degranulation on nasal cavity volume as well as on minimal cross-sectional area (A(min)) and intranasal distance to A(min) (D(min)) were studied. Compound 48/80 caused a dose-related decrease in nasal cavity volume and A(min) together with a variable increase in D(min). Maximal responses were seen at 90-120 min. Compound 48/80 was less effective in producing nasal congestion in conscious animals, which also had significantly larger basal nasal cavity volumes. These results demonstrate the utility of using acoustic rhinometry to measure parameters of nasal patency in dogs and suggest that this model may prove useful in studies of the actions of decongestant drugs.     

Prevalence of species of Toxocara in dogs, cats and red foxes from the Poznan region, Poland

The prevalence of toxocariasis was evaluated for 445 dogs, 105 cats and 92 foxes from the Poznan region during 1997-1998. Forty one cats were infected (39%), 140 dogs (32%) and 15 red foxes (16%). Toxocara canis was found most frequently in puppies up to 3 months old (58%) and T. cati in kittens 4-6 months old (64%). Toxocariasis was much more prevalent amongst adult foxes (14%) than adult dogs (3%). In contrast to cats, female dogs and foxes were less infected than males. The present study suggests that cats may constitute an underestimated risk of transmission of Toxocara spp. to humans and the progressive synatropization of red foxes may also increase the sources of environmental contamination with Toxocara eggs.     

Acoustic rhinometry: evaluation of nasal cavity geometry by acoustic reflection

To study the geometry of the nasal cavity we applied an acoustic method (J. Appl. Physiol. 43: 523-536, 1977) providing an estimate of cross-sectional area as a function of distance. Acoustic areas in a model constructed from a human nasal cast, in the nasal cavity of a cadaver and in 10 normal subjects and two patients with well-defined afflictions of the nasal cavity, were compared with similar areas obtained by computerized tomography (CT) scans, a specially developed water displacement method, and anterior rhinomanometry. We found a coefficient of variation of the areas of less than 2% by the acoustic method compared with 15% for the rhinomanometric measurements. Acoustic areas correlated highly to similar areas obtained by CT scanning (r = 0.94) and by water displacement (r = 0.96). In two patients the acoustic method accurately outlined, respectively, a tumor in the nose and a septum deviation. It is concluded that this method provides an accurate method for measuring the geometry of the nasal cavity. It is easy to perform and is potentially useful for investigation of physiological and pathological changes in the nose.     

Staphylococci Isolated from Carriage Sites and Infected Sites of Dogs as a Reservoir of Multidrug Resistance and Methicillin Resistance

The aim of this study was to compare the spread of multidrug-resistant (MDR) and methicillin-resistant (MR) staphylococci in healthy dogs and in dogs with evident symptoms of infection. The samples from 172 healthy and 197 infected dogs were examined. The staphylococci were identified with conventional methods and by means of the polymerase chain reaction–restriction fragment length polymorphism (PCR–RFLP) method (MboI). Susceptibility to 15 antibiotics from 10 different antimicrobial classes was tested. Resistance to methicillin was confirmed by the presence of Staphylococcus aureus mecA and S. sciuri mecA genes. Multidrug resistance was defined as resistance to three or more antimicrobial classes. The oral mucosa to be the most frequent site of staphylococcal colonization (55.8 %), followed by nasal cavity (44.2 %), and anus (32.6 %). The prevalence of MDR staphylococci in infected dogs was significantly higher than in the healthy animals (74/137 vs. 34/95, P = 0.006). The MR strains of S. pseudintermedius (2.9 %) originated solely from infected dogs. In contrast, the MR coagulase-negative strains (7.4 %) were isolated solely from healthy dogs. S. aureus strains originated from nasal swabs, MRSA strains were not isolated. MDR staphylococci and MR S. pseudintermedius are more common among infected dogs, but coagulase-negative staphylococci (mostly S. sciuri) seem to be a reservoir of methicillin resistance in healthy dogs.     

Nasal Staphylococcus aureus and S. pseudintermedius carriage in healthy dogs and cats: a systematic review of their antibiotic resistance,virulence and genetic lineages of zoonotic relevance

The molecular ecology of Staphylococcus aureus, Staphylococcus pseudintermedius and their methicillin-resistant strains in healthy dogs and cats could serve as good models to understand the concept of bacterial zoonosis due to animal companionship. This study aims to provide insights into pooled prevalence, genetic lineages, virulence and antimicrobial resistance (AMR) among healthy dogs and cats. Original research and brief communication articles published from 2001 to 2021 that reported the nasal detection of S. aureus and S. pseudintermedius in healthy dogs and cats in the community, homes and outside veterinary clinics were examined and analysed. Forty-nine studies were eligible and included in this systematic review. The pooled prevalence of nasal carriage of S. aureus/methicillin-resistant S. aureus (MRSA) in healthy dogs and cats were 10.9% (95% CI: 10.1–11.9)/2.8% (95% CI: 2.4–3.2) and 3.2% (95% CI: 1.9–4.8)/0.5% (95% CI: 0.0–1.1), respectively. Conversely, the pooled prevalence of S. pseudintermedius/methicillin-resistant S. pseudintermedius (MRSP) in healthy dogs and cats were 18.3% (95% CI: 17.1–19.7)/3.1% (95% CI: 2.5–3.7) and 1.3% (95% CI: 0.6–2.4)/1.2% (95% CI: 0.6–2.3), respectively. Although highly diverse genetic lineages of S. aureus were detected in healthy dogs and cats, MSSA-CC1/CC5/CC22/CC45/CC121/CC398 and MRSA-CC5/CC93/CC22/CC30 were mostly reported in dogs; and MSSA-CC5/CC8/CC15/CC48 and MRSA-CC22/CC30/CC80 in cats. Of note, MSSA-CC398 isolates (spa-types t034 and t5883) were detected in dogs. Genetic lineages often associated with MSSP/MRSP were ST20/ST71, highlighting the frequent detection of the epidemic European MRSP-ST71 clone in dogs. S. aureus isolates carrying the luk-S/F-PV, tst, eta, etb and etd genes were seldomly detected in dogs, and luk-S/F-PV was the unique virulence factor reported in isolates of cats. S. pseudintermedius isolates harbouring the luk-S/F-I, seint and expA genes were frequently found, especially in dogs. High and diverse rates of AMR were noted, especially among MRSA/MRSP isolates. There is a need for additional studies on the molecular characterization of isolates from countries with under-studied nasal staphylococci isolates.     

The Influence of Obturators on the Respiration of Patients with Maxillary Defects: A Clinical Study

The study evaluated the effects of obturators on respiratory function by analyzing the changes in nasal anatomic structures and physiologic function in maxillectomy patients with and without obturators. Twenty-six patients who underwent maxillectomy were chosen and rehabilitated with obturators by a single maxillofacial prosthodontist. The geometric shape of the nasal cavity, the nasal airway resistance, and the ratio of residual volume to total lung capacity (RV/TLC) were evaluated using acoustic rhinometry, rhinomanometry, and a pulmonary function test apparatus, respectively. All patients were tested twice, with and without their obturators. The results were statistically analyzed with a paired t-test. The nasal cavities (0–7 cm to the anterior nostril) of the patients with obturators had a significantly smaller volume ([-8.92, -0.60], P = 0.027), smaller effective nasal cross-sectional area MCA2 ([-3.80, -1,81], P<0.0001), increased airflow in the nasal cavity ([17.76, 147.39], P = 0.015), reduced nasal airway resistance ([-0.11, -0.02], P = 0.009), and reduced RV/TLC ([-5.32, -1.30], P = 0.004) compared with the patients without obturators. According to the results of this study, obturators can improve respiratory function by effectively decreasing the volume of enlarged nasal cavities as well as the nasal air resistance and volume of anatomical dead space after maxillectomy.

Trial Registration

ChiCTR.org ChiCTR-PRNRC-14005136     

Epidemiological Findings and Laboratory Evaluation of Sporotrichosis: A Description of 103 Cases in Cats and Dogs in Southern Brazil

Sporotrichosis is a subcutaneous mycosis, which affects mainly small animals, and is considered an important public health disease. This paper describes the epidemiological and laboratory characteristics of 103 clinical cases of sporotrichosis diagnosed over a 10-year period in southern Brazil. The 92 cats and 11 dogs from eight municipalities in Rio Grande do Sul State developed especially the disseminated cutaneous and fixed cutaneous forms of the disease. Respiratory signs such as sneezing, serous nasal discharge and dyspnea were found in about 57% of the animals. The detection of Sporothrix schenckii in different clinical samples showed highest isolation in testicles (46.6%), oral cavity (45.2%) and conjunctival mucosa (38.1%). A differentiated histological pattern was found between the fixed cutaneous and disseminated cutaneous (DC) manifestations of the disease; well-organized granulomas of nodular distribution and various fungal structures prevailed in the DC form in cats. Melanin detection in S. schenckii cells by the Fontana–Masson technique was positive in 45.4% of the samples. The study revealed that the State of Rio Grande do Sul is an endemic sporotrichosis area and demonstrated the possibility of involvement of other pathways in the infection and spread of the disease. In addition, it emphasized the importance of laboratory tests for mycosis confirmation, especially in dogs that develop clinical manifestations without the presence of cutaneous lesions.     

Functional characteristics of canine costal and crural diaphragm

We estimated the in situ force-generating capacity of the costal and crural portions of the canine diaphragm by relating in vitro contractile properties and diaphragmatic dimensions to in situ lengths. Piezoelectric crystals were implanted on right costal and left crural diaphragms of anesthetized dogs, via midline laparatomy. With the abdomen reclosed, diaphragm lengths were recorded at five lung volumes. Contractile properties of excised muscle bundles were then measured. In vitro force-frequency and length-tension characteristics of the costal and crural diaphragms were virtually identical; their optimal force values were 2.15 and 2.22 kg/cm2, respectively. In situ, at residual volume, functional residual capacity (FRC), and total lung capacity the costal diaphragm lay at 102, 95, and 60% of optimal length (Lo), whereas the crural diaphragm lay at 88, 84, and 66% of Lo. Muscle cross-sectional area was 40% greater in costal than in crural diaphragms. Considering in situ lengths, cross-sectional areas, and in vitro length-tension characteristics at FRC, the costal diaphragm could exert 60% more force than the crural diaphragm.     

Large area sectioning for morphologic studies of nonhuman primate nasal cavities

The nasal region is important for studies in inhalation toxicology but is difficult to prepare for histological examination, especially in species as large as primates. A method for the histologic preparation of undecalcified, complete transverse sections of the nonhuman primate nasal cavity is summarized as follows. After removal of excess soft tissue, mandible and calvaria, the head is fixed in 10% neutral buffered formalin. The nasal region is transversely sectioned into serial 3-mm-thick blocks from the nares to the posterior aspect of the soft palate using a low speed saw with a water-cooled diamond-coated blade. The blocks are embedded in a mixture of glycol and methyl methacrylates, with polyethylene glycol-1500 and dibutylphthalate as plasticizers. The plastic blocks average 5.0 x 5.0 x 1.5 cm; 2-4 microns sections are cut on an automated sliding microtome. In spite of the size of the blocks, this technique yields complete transverse sections of the nasal cavities with excellent morphologic detail. The sections are amenable to a wide range of staining procedures. The procedure lends itself to autoradiographic studies. The embedding mixture is ideally suited for studies of undecalcified bone and teeth.     

A guest molecule-host cavity fitting algorithm to mine PDB for small molecule targets

Inhaled anesthetic molecule occupancy of a protein internal cavity depends in part on the volumes of the guest molecule and the host site. Current algorithms to determine volume and surface area of cavities in proteins whose structures have been determined and cataloged make no allowance for shape or small degrees of shape adjustment to accommodate a guest. We developed an algorithm to determine spheroid dimensions matching cavity volume and surface area and applied it to screen the cavities of 6,658 nonredundant structures stored in the Protein Data Bank (PDB) for potential targets of halothane (2-bromo-2-chloro-1,1,1-trifluoroethane). Our algorithm determined sizes of prolate and oblate spheroids matching dimensions of each cavity found. If those spheroids could accommodate halothane (radius 2.91 A) as a guest, we determined the packing coefficient. 394,766 total cavities were identified. Of 58,681 cavities satisfying the fit criteria for halothane, 11,902 cavities had packing coefficients in the range of 0.46-0.64. This represents 20.3% of cavities large enough to hold halothane, 3.0% of all cavities processed, and found in 2,432 protein structures. Our algorithm incorporates shape dependence to screen guest-host relationships for potential small molecule occupancy of protein cavities. Proteins with large numbers of such cavities are more likely to be functionally altered by halothane.     

Synthesis and SAR of benzyl and phenoxymethylene oxadiazole benzenesulfonamides as selective beta3 adrenergic receptor agonist antiobesity agents

Benzyl and phenoxymethylene substituted oxadiazoles are potent and orally bioavailable beta3 adrenergic receptor (AR) agonists. The 4-trifluormethoxy substituted 5-benzyl oxadiazole 5f has an EC50 of 8 nM in the beta3 AR agonist assay with 100-fold selectivity over beta1 and beta2 AR binding inhibition activity. Its oral bioavailability in dogs is 30 +/- 4%, with a half-life of 3.8 +/- 0.4 h. In the anesthetized rhesus, 5f evoked a dose-dependent glycerolemia (ED50Gly = 0.15 mg/kg). Under these conditions a heart rate increase of 15% was observed at a dose level of 10 mg/kg.     

Large Area Sectioning for Morphologic Studies of Nonhuman Primate Nasal Cavities

The nasal region is important for studies in inhalation toxicology but is difficult to prepare for histological examination, especially in species as large as primates. A method for the histologic preparation of undecalcified, complete transverse sections of the nonhuman primate nasal cavity is summarized as follows. After removal of excess soft tissue, mandible and calvaria, the head is fixed in 10% neutral buffered formalin. The nasal region is transversely sectioned into serial 3-mm-thick blocks from the nares to the posterior aspect of the soft palate using a low speed saw with a water-cooled diamond-coated Made. The blocks are embedded in a mixture of glycol and methyl methacrylates, with polyethylene glycol-1500 and dibutylphthalate as plasticizers. The plastic blocks average 5.0 × 5.0 × 5.1 cm; 2-4 μn sections are cut on an automated sliding microtome. In spite of the size of the blocks, this technique yields complete transverse sections of the nasal cavities with excellent morphologic detail. The sections are amenable to a wide range of staining procedures. The procedure lends itself to autoradiographic studies. The embedding mixture is ideally suited for studies of undecalcified bone and teeth.     

Prevalence of flea infestation in dogs and cats in Hungary combined with a survey of owner awareness

A survey was conducted in order to gain current information on flea species (Siphonaptera: Pulicidae) infesting dogs and cats living in urban and rural areas of Hungary, along with data on the factors that affect the presence, distribution and seasonality of infestation. In addition, owner awareness of flea infestation was evaluated. Practitioners in 13 veterinary clinics were asked to examine all dogs and cats attending the clinic and to collect fleas, when present, on 2 days in each month from December 2005 to November 2006. They also completed a questionnaire for each animal examined. A total of 319 dogs (14.1%) were found to be infested; the highest prevalence (27.1%) of infestation on dogs occurred in August and the lowest (5.4%) in May. Prevalence of fleas on cats was higher (22.9%); the highest (35.0%) and lowest (8.1%) prevalences occurred in July and April, respectively. Fleas were more prevalent in rural (387/1924 animals, 20.2%) than in urban (161/1343 animals, 12.0%) areas. Three species, Ctenocephalides felis (Bouché), Ctenocephalides canis (Curtis) and Pulex irritans L., were found. On dogs, the prevalence of C. canis alone was 53.0%, whereas that of C. felis alone was 36.0%. Only 19 specimens of P. irritans were found on 14 dogs from rural habitats only. Prevalence of C. felis only on cats was 94.3%; the remaining cats were infested with either C. canis or with mixed infestations of C. felis and C. canis. More than half (51.4%) of the owners of infested dogs and cats had not used flea control products in the past year or more, and five times as many owners in rural than urban areas had not used flea control products in the same period. Very few owners reported having attempted to kill fleas in their animals' environment; instead, they believed that fleas were acquired from other cats or dogs.