The course of the nasolacrimal duct in brachycephalic cats

Influence of feline brachycephaly on respiratory, gastrointestinal, sleep, and activity abnormalities

OBJECTIVE

To determine the influence of brachycephaly on respiratory, gastrointestinal, sleep, and activity-related parameters in cats.

STUDY DESIGN

Prospective questionnaire-based study.

ANIMALS

A total of 194 BC and 1003 non-BC cats.

METHODS

Owners completed an online questionnaire regarding respiratory, gastrointestinal, sleep, and activity-related parameters. Response options were scored, and individual scores summed to give a total clinical severity score for each cat.

RESULTS

Brachycephalic cats had more frequent snoring (odds ratio [OR] 6.89; 95% confidence interval [CI]: 5.06-9.41), sneezing (OR 6.52; CI: 4.75-8.98), nasal discharge (OR 8.26; 95% CI 5.77-11.85), coughing (OR 1.75; CI: 1.17-2.59), and dyspnea (OR 5.32; CI: 3.42-8.28); shorter activity before becoming dyspneic (OR 2.71; CI: 1.93-3.79), slower recovery from activity (OR 3.17; CI: 2.19-4.57), lower activity levels (OR 2.16; CI: 1.59-2.95), and increased respiratory noise (OR 6.68; CI: 4.71-9.52); and more hypersalivation (OR 2.50; CI: 1.47-4.16), halitosis (OR 1.40; CI: 1.00-1.95), and difficulty chewing (OR 5.19; CI: 3.65-7.38). Median clinical severity scores were higher for BC cats than non-BC cats (p < .0001).

CONCLUSIONS

Brachycephalic cats (BC) were at risk for respiratory, gastrointestinal, and activity-related symptoms compared to non-BC cats.

CLINICAL RELEVANCE

Some BC cats exhibit clinically relevant symptoms and behaviors as reported by owners. Medical or surgical interventions may improve these symptoms and warrant investigation.

Ala vestibuloplasty improves cardiopulmonary and activity-related parameters in brachycephalic cats

OBJECTIVE

To evaluate the effects of ala vestibuloplasty on cardiopulmonary and lifestyle-related parameters in brachycephalic (BC) cats.

STUDY DESIGN

Prospective cohort.

ANIMALS

Client-owned BC cats (n = 19).

METHODS

Cats were assessed preoperatively by airway computed tomography (CT), endoscopy, contrast echocardiography, cardiac biomarkers, and structured owner questionnaire. Ala vestibuloplasty was performed bilaterally, and blood values, imaging, and owner questionnaire responses were re-evaluated 8-20 weeks postoperatively.

RESULTS

Cats were presented for predominantly respiratory clinical signs attributable to brachycephaly. Preoperatively, all cats had stenotic nares, prolonged normalized pulmonary transit time (nPTT) (mean 5.43 ± 1.10 s), and a hyperattenuating pulmonary pattern. No complications occurred following surgery. Postoperatively, nPTT (mean 3.89 ± 0.74 s, p < .001) and frequencies of sneezing (p = .002), snoring (p = .006), open-mouth breathing (p = .0004), and nasal discharge (p = .019) were decreased. Cats exhibited increased activity (p = .005), less frequent dyspnea during activity (p < .001), longer duration of activity before becoming dyspneic (p = .002), faster recovery from activity (p < .001), and decreased respiratory noise (p < .001). Median questionnaire scores improved from preoperative to postoperative (p < .001).

CONCLUSION

Anatomic, echocardiographic, and CT changes were common in this cohort of clinically affected BC cats. Pulmonary blood flow and respiratory function were improved after surgery.

CLINICAL SIGNIFICANCE

Stenotic nares are the predominant airway abnormality in BC cats. Ala vestibuloplasty is a safe procedure that improves cardiac and CT abnormalities and respiratory and other clinical signs in BC cats.

Tear film breakup time and Schirmer tear test in normal dogs: Effects of age, sex, reproductive status, skull type, and nasolacrimal duct patency

OBJECTIVE

The present study aimed to determine the effects of age, sex, reproductive status, skull type, and nasolacrimal duct (NLD) patency on tear production and tear film breakup time (TBUT) in normal dogs.

ANIMALS STUDIED

The ophthalmic data of 82 healthy adult dogs were evaluated in this study.

PROCEDURES

Age, sex, breed, and reproductive status were recorded. Schirmer tear test (STT) and TBUT were assessed in all dogs, and interferometry was available for the selected dogs. The Jones test was used to evaluate NLD patency. The cephalic index (CI) was calculated for each dog (skull width/skull length ×100).

RESULTS

Mean (SD) values for the STT results for the right (OD) and left (OS) eyes were 20.6 (2.7) and 20.2 (2.7) mm/min, respectively. Mean (SD) TBUT values for OD and OS were 6.5 (2.5) and 6.1 (2.3) mm/min in all dogs, respectively. Sex and reproductive status had no significant effect on STT and TBUT (P_[OU]  > 0.05). Skull type significantly affected TBUT in both eyes (P_(OD)  = 0.01, P_(OS)  = 0.003), but had no effect on STT (P_[OU]  > 0.3). Age had no correlation with STT and TBUT in either eye (P_[OU]  > 0.05). STT and TBUT had no correlation in either eye (P_[OU]  > 0.2). NLD patency had no significant effect on STT or TBUT (P_[OU]  > 0.1).

CONCLUSIONS

The results of this study showed lower TBUT values in brachycephalic breeds than in non-brachycephalic breeds. A compensatory increase in STT values was observed in dogs with low TBUT values.

Anatomy of the nasolacrimal duct in Persian cats determined by computed tomographic dacryocystography

OBJECTIVE

This study sought to describe the anatomical characteristics of the nasolacrimal duct of Persian cats as observed by computed tomographic dacryocystography.

ANIMAL STUDIED

Ten cats weighing 3-6 kg (three live cats and seven cadaveric specimens).

PROCEDURES

The animals were submitted to bilateral computed tomographic dacryocystography, totaling 20 nasolacrimal ducts. Dorsal, sagittal, and transverse planes were studied. Two additional skulls were also dissected following latex injection into the nasolacrimal duct. The length and width of the nasolacrimal duct and lacrimal canaliculi, and the distance between the nasolacrimal duct and the root of the upper canine tooth at the point of closest proximity were measured.

RESULTS

The nasolacrimal duct followed a convoluted course, particularly in the middle and rostral portions. Duct stenosis (width reduction equal to or >75%) and dilations (width increase equal to or >50%) were also detected, particularly in the rostral portion. Nasolacrimal duct length and width ranged from 1.3 to 1.5 cm and 1.5 to 2.3 mm, respectively. Mean lacrimal canaliculus length and width corresponded to 3.1 mm and 0.4 mm, respectively. Mean distance from the nasolacrimal duct to the canine tooth was 2.4 mm. The root of this tooth interfered with the course of the nasolacrimal duct.

CONCLUSION

This study provided anatomical information for clinical assessment of the nasolacrimal drainage system in Persian cats.

Facial conformation characteristics in Persian and Exotic Shorthair cats

OBJECTIVES

The primary objectives of the study were to examine the diversity in facial conformation characteristics within a group of Persian (PER) and Exotic Shorthair (EXO) show cats, and to contrast the results to findings within a group of non-purebred domestic shorthair (DSH) and domestic longhair (DLH) cats. The secondary objectives were to determine the PER/EXO show cat owners' perceptions of the breathing status of their cats, and to evaluate if remarks from the cat show judges concerning the cats' head and facial conformation were exclusively related to the aesthetic features of the cats.

METHODS

Sixty-four PER and 12 EXO show cats were prospectively examined at five international cat shows, and 20 DSH/DLH cats were examined at an animal hospital. Facial conformation characteristics were evaluated by examining photos of the cats. Owners of the PER/EXO show cats answered a questionnaire concerning their cats' health status, and they were encouraged to send in the judges' score sheets from the cat shows.

RESULTS

The PER/EXO show cats had higher diversity in facial conformation characteristics than the DSH/DLH cats, and high incidences of hypoplasia of the nose leather (95%), the nose leather top positioned above the level of the lower eyelid (93%), moderate-to-severe stenotic nares (86%), epiphora (83%) and entropion (32%). Owners of 6/76 PER/EXO show cats stated that their cat had increased respiratory sounds and/or trouble breathing at least once a week. The cat show judges' written comments were exclusively related to aesthetic features of the cats' head and facial conformation details.

CONCLUSIONS AND RELEVANCE

Hypoplasia of the nose leather, high position of the nose leather top, stenotic nares, epiphora and entropion were common findings in the PER/EXO show cats but not in the DSH/DLH cats. Few of the cat owners perceived that their cat had problems related to the airways.

Evaluating malformations of the lacrimal drainage system in brachycephalic dog breeds: A comparative computed tomography analysis

OBJECTIVES

This study aimed to investigate and compare the anatomical features of the nasolacrimal drainage system (NDS) in three brachycephalic dog breeds with those of normocephalic dogs, taking into account how the NDS was related to the malformed brachycephalic head.

ANIMALS

Fifty-one brachycephalic dogs were examined, comprising 23 Pugs, 18 French Bulldogs, and 10 English Bulldogs. Six normocephalic dogs of different breeds served as a comparison.

METHODS

Computed tomographic dacryocystography was performed. Parameters such as length, angulation, and gradient were determined. Crossing of the nasolacrimal duct (NLD) beneath the maxillary canine root, as well as the incidence of an accessory opening, were also analyzed.

RESULTS AND CONCLUSIONS

In all three brachycephalic breeds, the NDS was grossly malformed. We regard this as a further consequence of exaggerated breeding for a short head conformation. While the length of the NLD was substantially reduced by 41 to 57 percent in brachycephalic dogs, their lacrimal canaliculi were two to three times as long as those of normocephalic dogs. Varying parts of the nasolacrimal drainage system followed an inverse direction in short-headed dogs, giving the entire nasolacrimal apparatus an anomalous U- or V-shaped appearance. The NLD exhibited a three to five times steeper alignment in brachycephalic dogs than in normocephalic ones. Obviously, this strong slope did not cause clinical symptoms only because there was an aberrant outflow pathway. The brachycephalic dogs consistently exhibited an accessory opening, through which most of fluid escaped into the posterior nasal cavity instead of through the common route into the nasal vestibule via the nasolacrimal ostia.

Comparison of conjunctival microbiota of clinically normal Persian cats with and without nasolacrimal duct obstruction

OBJECTIVE

This study was performed to determine the conjunctival microbiota of Persian cats with and without nasolacrimal duct obstruction (NLDO).

ANIMALS STUDIED

Twenty-five Persian cats: 15 with bilateral NLDO (Group A) and 10 with no NLDO (Group B).

PROCEDURES

All fifty eyes were assessed. Sterile swab applicators were used for the collection of specimens, which were cultured. PCR was performed on conjunctival swab and blood samples for the detection of Mycoplasma spp. and feline herpesvirus 1(FHV-1), respectively.

RESULTS

FHV-1 was detected in two cats in Group A. Twelve eyes from Group A and four from Group B were Mycoplasma spp. positive based on the PCR results. Moreover, fungal culture was positive in six eyes from Group A and three eyes from Group B. The dominant fungus isolated was Aspergillus spp. (6 out of 11 fungal isolates). Other isolated fungi were Alternaria spp. and Cladosporidium spp. Twenty-three eyes had positive bacterial culture in Group A, while twelve eyes were positive in Group B. The most commonly isolated bacteria were Staphylococcus epidermidis (15 out of 38 bacterial isolates). β-hemolytic Streptococcus spp., Corynebacterium spp., and Staphylococcus aureus were isolated in similar proportions in both groups. Escherichia coli was also present in both groups.

CONCLUSIONS

Results of this study revealed same isolated fungal and bacterial spp. and in similar proportions in Persian cats with and without NLDO.

Exceptional Changes in Skeletal Anatomy under Domestication: The Case of Brachycephaly

"Brachycephaly" is generally considered a phenotype in which the facial part of the head is pronouncedly shortened. While brachycephaly is characteristic for some domestic varieties and breeds (e.g., Bulldog, Persian cat, Niata cattle, Anglo-Nubian goat, Middle White pig), this phenotype can also be considered pathological. Despite the superficially similar appearance of "brachycephaly" in such varieties and breeds, closer examination reveals that "brachycephaly" includes a variety of different cranial modifications with likely different genetic and developmental underpinnings and related with specific breed histories. We review the various definitions and characteristics associated with brachycephaly in different domesticated species. We discern different types of brachycephaly ("bulldog-type," "katantognathic," and "allometric" brachycephaly) and discuss morphological conditions related to brachycephaly, including diseases (e.g., brachycephalic airway obstructive syndrome). Further, we examine the complex underlying genetic and developmental processes and the culturally and developmentally related reasons why brachycephalic varieties may or may not be prevalent in certain domesticated species. Knowledge on patterns and mechanisms associated with brachycephaly is relevant for domestication research, veterinary and human medicine, as well as evolutionary biology, and highlights the profound influence of artificial selection by humans on animal morphology, evolution, and welfare.

Motivation of Owners to Purchase Pedigree Cats, with Specific Focus on the Acquisition of Brachycephalic Cats

Background: Cats are globally popular pets and pedigree cats are increasingly prevalent, with brachycephalic breeds being the most registered breeds. How owners decide upon and acquire their cats is poorly understood. Moreover, there are growing concerns about the health and welfare of brachycephalic (BC) dogs and recent studies are raising the awareness of health and welfare problems in BC cats. Methods: An online survey investigated owners' motivations, perceptions and behaviours prior to, during and following acquisition of non-pedigree (NP), extreme brachycephalic pedigree (BC; i.e., Persian and Exotic Shorthair) and mild to non-BC pedigree (P) cats. Results: The survey received 1367 valid responses (NP n = 882, P n = 400, BC n = 85 (6.2%)). There were marked differences between NP, P and BC owners' perception of their cats' health and welfare, reason(s) for acquisition and its process. Owners of NP were less influenced by appearance, behaviour and other features than P or BC owners. In contrast, P and BC owners were highly influenced by appearance, with P owners also placing greater importance on good breed health than BC owners. BC owners were less likely to recommend their breeds to prospective cat owners, apparently concerned by high maintenance requirements. Conclusion: Further research is needed to determine how decision-making is constructed and how it may be improved, especially in respect of welfare outcomes for extreme BC cats given the increased weighting given to appearance over health.

Evaluation of tear production using the Schirmer tear test I in healthy cats; effect of age, life stage, sex, breed and neuter status

BACKGROUND

The purpose of this study was to evaluate the values of Schirmer tear test (STT) and determine effects of age, life stage, sex, breed and neuter status on tear production in healthy cats.

METHODS

Three hundred and forty-three domestic shorthair (DSH) and Persian cats, 50 days through 18 years old, were examined in this study. STT I was used to measure tear production in both eyes of each cat.

RESULTS

A mean STT 14.9±4.8 mm/min was calculated for the eyes of all cats. There was a significant difference between STT values in kittens (≤6 months old) and cats of other age groups (P<0.001). A substantial number of cats with clinically normal eyes had STT values less than 10 mm/min. No significant difference was found between males (14.7±5.0 mm/min) and females (15.1±4.5 mm/min) in STT values (P=0.46). Significant differences were found between entire (14.4±4.2 mm/min) and neutered (16.2±4.1 mm/min) cats (P=0.001), and between STT values of DSH (14.6±5.0 mm/min) and Persian (16.5±3.1 mm/min) cats in the study population (P=0.001).

CONCLUSIONS

This study documents the average STT values for a sizeable feline population demonstrating that, in contradistinction to the situation in dogs, a number of cats with clinically normal eyes have STT values below 10 mm/min.

Flat Feline Faces: Is Brachycephaly Associated with Respiratory Abnormalities in the Domestic Cat (Felis catus)?

There has been little research into brachycephalism and associated disorders in cats. A questionnaire aimed at cat owners was used to determine the relationship between feline facial conformation and owner-reported cat management requirements and respiratory abnormalities. Owner-submitted photographs of cats were used to develop novel measures of skull conformation. One thousand valid questionnaires were received. Within these there were 373 valid photographs that allowed measurement of muzzle ratio (M%) and 494 that allowed nose position ratio (NP%). The data included 239 cats for which both measurements were available. Owners reported lifestyle factors (e.g. feeding type, grooming routine, activity level), physical characteristics (e.g. hair length) and other health characteristics of their cat (e.g. tear staining, body condition score). A composite respiratory score (RS) was calculated for each cat using their owner’s assessment of respiratory noise whilst their cat was asleep and then breathing difficulty following activity. Multivariate analyses were carried out using linear models to explore the relationship between RS and facial conformation, and lifestyle risk factors. The results showed that reductions in NP% and M% were significantly associated with RS (P < 0.001 and P = 0.026, respectively) and that the relationship was significantly negatively correlated (r = -0.56, P < 0.001 for both). Respiratory score was also significantly associated with increased presence of tear staining (P < 0.001) and a sedentary lifestyle (P = 0.01). This study improves current knowledge concerning cats with breeding-related alterations in skull confirmation and indicates that brachycephalism may have negative respiratory implications for cat health and welfare, as has been previously shown in dogs.

Development of the nasolacrimal apparatus in the Mongolian gerbil (Meriones unguiculatus), with notes on network topology and function

The nasolacrimal apparatus (NLA) is a multicomponent functional system comprised of multiple orbital glands (up to four larger multicellular exocrine structures), a nasal chemosensory structure (vomeronasal organ: VNO), and a connecting duct (nasolacrimal duct: NLD). Although this system has been described in all tetrapod vertebrate lineages, albeit not always with all three main components present, considerably less is known about its ontogeny. The Mongolian gerbil (Meriones unguiculatus) is a common lab rodent in which the individual components of the adult NLA have been well studied, but as yet nothing is known about the ontogeny of the NLA. In this study, serial sections of 15 fetal and three adult Mongolian gerbil heads show that the development of the NLA falls into three fetal stages: inception (origin of all features), elongation (lengthening of all features), and expansion (widening of all features). No postnatal or juvenile specimens were observed in this study, but considerable growth evidently occurs before the final adult condition is reached. The development of the orbital glands and the VNO in the Mongolian gerbil is largely consistent with those in other mammals, despite a slight nomenclatural conundrum for the anterior orbital glands. However, the Mongolian gerbil NLD follows a more circuitous route than in other tetrapods, due mainly to the convoluted arrangement of the narial cartilages, the development of a pair of enlarged incisors as well as an enlarged infraorbital foramen. The impact of these associated features on the ontogeny and phylogeny of the NLA could be examined through the approach of network science. This approach allows for the incorporation of adaptations to specific lifestyles as potential explanations for the variation observed in the NLA across different tetrapod clades.

Gross, histologic, and micro-computed tomographic anatomy of the lacrimal system of snakes

OBJECTIVE

To describe the lacrimal system of snakes using contrast micro-computed tomography (micro-CT) with 3-dimensional reconstruction, fluorescein passage ('Jones') testing, histology, and gross dissection.

ANIMALS STUDIED

One royal python and 19 snake cadavers representing 10 species.

PROCEDURES

Direct observation following injection of fluorescein into the subspectacular space, micro-CT following injection of three contrast agents into the subspectacular space, gross dissection following injection of latex into the subspectacular space, and histopathology.

RESULTS

Injection of fluorescein confirmed patency, but not course of the lacrimal duct. Barium enabled clear visualization of the lacrimal duct, whereas two iodinated contrast agents proved inadequate. Collectively, micro-CT, anatomic dissections, and histology suggest tears are produced by a single, large, serous, retrobulbar gland, released into the subspectacular space via several ductules, and drained through a single punctum originating in the ventronasal subspectacular space, and the lacrimal duct, which takes one of three routes of variable tortuosity before opening into the oral cavity in close association with the opening of the duct of the vomeronasal organ.

CONCLUSIONS

The ophidian lacrimal duct has a generally tortuous course, and the details of its anatomy are species-variable. The tortuous course of the duct likely predisposes snakes to duct occlusion and must be considered when planning medical and surgical interventions in snakes with pseudobuphthalmos and subspectacular abscessation.

Casting materials and their application in research and teaching

From a biological point of view, casting refers to filling of anatomical and/or pathological spaces with extraneous material that reproduces a three-dimensional replica of the space. Casting may be accompanied by additional procedures such as corrosion, in which the soft tissue is digested out, leaving a clean cast, or the material may be mixed with radiopaque substances to allow x-ray photography or micro computed topography (µCT) scanning. Alternatively, clearing of the surrounding soft tissue increases transparency and allows visualization of the casted cavities. Combination of casting with tissue fixation allows anatomical dissection and didactic surgical procedures on the tissue. Casting materials fall into three categories namely, aqueous substances (India ink, Prussian blue ink), pliable materials (gelatins, latex, and silicone rubber), or hard materials (methyl methacrylates, polyurethanes, polyesters, and epoxy resins). Casting has proved invaluable in both teaching and research and many phenomenal biological processes have been discovered through casting. The choice of a particular material depends inter alia on the targeted use and the intended subsequent investigative procedures, such as dissection, microscopy, or µCT. The casting material needs to be pliable where anatomical and surgical manipulations are intended, and capillary-passable for ultrastructural investigations.

Dacryocystography in a cat with orbital pneumatosis

A 2-year-old neutered male European short-haired cat was presented for a persistent discharge from the scar of previous left eye enucleation, performed 6 months prior by the referring veterinarian. A surgical exploration of the orbit was performed and retained nictitating membrane glandular and conjunctival tissues were removed. Eleven days later, the cat developed an orbital pneumatosis caused by retrograde movement of air through a patent nasolacrimal system and diagnosed by survey radiographic examination of the skull. Nasolacrimal system patency was assessed by dacryocystography performed by injection of iodinated contrast medium under pressure into the orbital cavity. Computed tomography dacryocystography confirmed the radiographic findings. The condition resolved following dacryocystography, possibly as an inflammatory response to the contrast medium. To our knowledge, this is the first case of orbital pneumatosis reported in a cat.

Rare case of nasolacrimal duct opening into face

Congenital anomaly of nasolacrimal duct is mostly obstructive in nature or is seen in oblique facial clefts. Nasolacrimal duct drain into the inferior meatus in the nose in a normally developed face. We report a rare case of aberrant opening of distal end of nasolacrimal duct into the external skin lateral to the ala of nose in an adult patient. The only case reported so far was in an infant. The patient is a 22 year young male presenting with an opening lateral to the left ala of nose with recurrent discharge and conjunctivitis of left eye. The embryology is also discussed.

Development of the Lacrimal Apparatus in the Rabbit (Oryctolagus cuniculus) and Its Potential Role as an Animal Model for Humans

Rabbits have been proposed as a model organism for the human lacrimal apparatus (LA), including the nasolacrimal duct (NLD), based principally on comparative studies of adult morphology; however, little is known about its development. The NLD first appears as an incomplete primordium in the subcutaneous region of the primordial eyelid and subsequently elongates to reach the naris. One posterior and three anterior orbital glands are present fetally although one of the anterior glands is soon lost. The NLD follows a tortuous path and passes through a bony canal consisting of lacrimal, maxilla, and maxilloturbinal bones at different regions. Although early developmental similarities exist to haplorhine primates, the narial opening of the NLD resembles strepsirrhines. This distinction, along with the ductal and glandular differences at the orbital end of the NLD, indicates that rabbits may be a poor model for LA drainage in primates, specifically humans.

Morbidity of insured Swedish cats during 1999-2006 by age, breed, sex, and diagnosis

The aim of the study was to describe patterns of morbidity, as reflected by reimbursed claims for veterinary care among cats covered by a Swedish insurance company during 1999-2006. The annual incidence rates of having at least one veterinary care event were calculated overall and stratified by sex, age, breed, diagnosis and urban/other location. The total rate was 875 (95% CI 858-892) cats with claims per 10,000 cat-years at risk. The Siamese, Burmese, and the Abyssinians had high rates of claims, compared to the Norwegian Forest cat, the Maine Coon, the European Shorthair and domestic cats. The most common causes for insurance claims were trauma, gastrointestinal and lower urinary tract problems and there was substantial breed, sex and age variation for certain problems. For example, among cats under 9 years of age, the rate for lower urinary tract problems was 2-3 times higher in males than females.

Evaluation of nasolacrimal fluorescein transit time in ophthalmically normal dogs and nonbrachycephalic cats

OBJECTIVE

To evaluate fluorescein nasolacrimal transit (NLT) times in ophthalmically normal dogs and nonbrachycephalic cats by use of 2 methods of the Jones test.

ANIMALS

73 dogs and 36 cats.

PROCEDURES

Fluorescein dye was applied to the ocular surface of both eyes by means of a wetted fluorescein strip and, in a subsequent test, by administration of a drop of 0.2% fluorescein solution. During each test, the nares were monitored for the appearance of fluorescein for up to 30 minutes after application. Time of fluorescein appearance at the nares was recorded as NLT time. Recorded variables for all study animals included age, reproductive status, body weight, and Schirmer tear test values. For dogs, skull index, snout length, and cephalic conformation were also recorded. Data were grouped for statistical comparisons according to test results.

RESULTS

In both dogs and cats, NLT was faster when the fluorescein solution versus fluorescein strip was used. In cats, none of the recorded variables had a significant effect on NLT, irrespective of the testing method used. In dogs, several variables had a significant effect on NLT, including cephalic conformation, snout length, age, and reproductive status, but these findings varied with testing method and testing group.

CONCLUSIONS AND CLINICAL RELEVANCE

NLT was highly variable in dogs and cats, regardless of testing method used. Assessment of nasolacrimal patency in brachycephalic dogs by use of either method evaluated here is not likely to be clinically useful. In cats, assessment of nasolacrimal patency with the fluorescein drop method was faster and more conclusive than with the fluorescein strip method.

Brachycephalic feline noses: CT and anatomical study of the relationship between head conformation and the nasolacrimal drainage system

AIMS

A study was designed to evaluate the influence of head conformation on the course of the nasolacrimal drainage system (NDS) in 31 brachycephalic and 15 mesocephalic cats using computed tomography (CT), CT-dacryocystography and anatomical methods.

FINDINGS

The higher the degree of brachycephalia, the more the facial bones and upper canine teeth are displaced dorsally (ie, the more pronounced the dorsorotation). Dorsorotation leads to abnormal dislocation of the ventral nasal concha and to almost horizontally rotated upper canine teeth, and thus a steeply oriented NDS. In severe brachycephalia the NDS is forced to pass below the canine tooth (adopt a V-shaped course) and the drainage function seems to be inefficient.

PRACTICAL RELEVANCE

The rotation of the upper canine teeth appears to provide a basis for classification of brachycephalia in cats. The authors recommend that breeders avoid breeding from individuals affected by this condition and to give preference to cats with longer facial bones.

The Swedish breeding cat: population description, infectious diseases and reproductive performance evaluated by a questionnaire

The questionnaire based study gives a combined description of management, infectious diseases and reproductive performance in breeding catteries during 1 year. The mean number of cats per cattery was 6.1, and 25% of the breeders let some of their cats have free access to outdoors. Breeders reported that infection with feline panleukopenia virus, feline immunodeficiency virus or feline leukaemia virus was uncommon, but 8% of the breeders had sold or had themselves owned a cat that died of feline infectious peritonitis. Presence of conjunctivitis was reported by 33.3% of the breeders. Mean litter size was 3.7 ± 1.5, with 9.7% stillbirths and 8.3% kitten mortality week 1–12. The percentage of stillborn kittens increased with the age of the queen and litter size, and also differed among breeds. Kitten mortality differed among breeds, but did not increase with age of the queen. Seven percent of the litters were delivered by caesarean section, significantly more during winter and positively associated with presence of stillborn kittens.

COMPUTED TOMOGRAPHY-ANATOMY OF THE NORMAL FELINE NASOLACRIMAL DRAINAGE SYSTEM

Computed tomography (CT) of the nasolacrimal drainage system with and without contrast medium (barium sulfate) was used to create an anatomic basis for clinical evaluation in domestic cats. To evaluate and compare the anatomical findings, three casts were carried out and were followed by CT examinations. These CT series were also used for a three-dimensional (3D) reconstruction of the nasolacrimal drainage system within surrounding structures. In noncontrast CT images, osseous structures limiting the nasolacrimal drainage system are easily recognizable. In most cats, this allows the identification of the nasolacrimal drainage system even without contrast enhancement. A distal part of the lacrimal sac adjoins directly to the respiratory mucosa of the nasal cavity without an osseous protection. Thus, this may represent a predilection site for infiltration of adjacent pathologic processes from the nasal cavity onto the lacrimal sac. The nasolacrimal duct begins on level with the maxillary third premolar tooth. The apex of the root of the canine tooth is situated very close to the nasolacrimal duct. This close topographic relation may lead to problems with the nasolacrimal drainage system. In domestic cats the nasolacrimal drainage system consists of a descending and a horizontal part, which form an angle of approximately 90 degrees for unhindered drainage of the lacrimal fluid.