Does blood contamination of urine compromise interpretation of the urine protein to creatinine ratio in dogs?

AIMS: To determine the effect of contamination of urine with 0-5% blood, varying in haematocrit and protein concentrations, on the urine protein to creatinine ratio (UPC) in dogs, and to determine whether the colour of urine can be used to aid interpretation of UPC results. METHODS: Urine samples were collected by free catch from 18 dogs, all of which had UPC <0.2. Venous blood samples were also collected from each dog, and the blood from each dog was added to its own urine to produce serial concentrations of 0.125-5% blood. The colour of each urine sample was recorded by two observers scoring them as either yellow, peach, orange, orange/red or red. Protein and creatinine concentrations were determined, and dipstick analysis and sediment examination was carried out on each sample. Based on colour and dipstick analysis, samples were categorised as either having microscopic, macroscopic or gross haematuria. A linear mixed model was used to examine the effect of blood contamination on UPC. RESULTS: The uncontaminated urine of all 18 dogs had a UPC <0.2. Adding blood to the urine samples resulted in an increase in UPC at all contamination concentrations compared to the non-contaminated urine (p<0.001). None of the 54 samples with microscopic haematuria had UPC >0.5. For 108 samples with macroscopic haematuria the UPC was >0.5 in 21 samples (19.4 (95% CI=13.1-27.9)%), and for 54 samples with gross haematuria 39 (72 (CI=59.1-82.4)%) had a UPC >0.5. No samples had a UPC >2.0 unless the blood contamination was 5% and only 3/18 (17%) samples at this blood contamination concentration had a UPC >2.0. CONCLUSIONS AND CLINICAL RELEVANCE: This study showed that while blood contamination of ≥0.125% does increase the UPC, if the urine remains yellow (microscopic haematuria), then there is negligible chance that a UPC >0.5 will be solely due to the added blood. In that scenario, attributing the proteinuria present to the haematuria in the sample would be inappropriate. However blood contamination that results in discolouration of the urine sample from yellow (indicating macroscopic or gross haematuria) could increase the UPC above the abnormal range and would need to be considered as a differential for the proteinuria. Thus knowledge of urine colour, even if limited to simple colour scores (yellow, discoloured, red) could be utilised to aid interpretation of the UPC in samples with haematuria.

Bacteriophage therapy for management of bacterial infections in veterinary practice: what was once old is new again.

Bacteriophages (or phages) are naturally-occurring viruses that can infect and kill bacteria. They are remarkably diverse, numerous and widespread. Each phage has a narrow host range yet a large majority of bacteria studied so far play host to bacteriophages, hence the remarkable phage diversity. Phages were discovered just over 100 years ago and they have been used for treatment of bacterial infections in humans and other animals since the 1920s. They have also been studied intensively and this has led to, and continues to lead to, major insights in the fields of molecular biology and recombinant DNA technology, including that DNA is the genetic material, nucleotides are arranged in triplets to make codons, and messenger RNA is needed for protein synthesis. This article begins with a description of bacteriophages and explains why there has recently been a strong resurgence of interest in their clinical use for treatment of bacterial infections, particularly those caused by organisms resistant to multiple antimicrobial compounds. The history of bacteriophage therapy is briefly reviewed, followed by a review and critique of promising but very limited clinical research on the use of bacteriophages to treat bacterial infections in dogs. Other potential veterinary uses and benefits of bacteriophage therapy are also briefly discussed. There are important practical challenges that will have to be overcome before widespread implementation and commercialisation of bacteriophage therapy can be achieved, which are also considered.

Feline immunodeficiency virus (FIV) infection in domestic pet cats in Australia and New Zealand: Guidelines for diagnosis, prevention and management.

Despite the passage of over 30 years since its discovery, the importance of feline immunodeficiency virus (FIV) on the health and longevity of infected domestic cats is hotly debated amongst feline experts. Notwithstanding the absence of good quality information, Australian and New Zealand (NZ) veterinarians should aim to minimise the exposure of cats to FIV. The most reliable way to achieve this goal is to recommend that all pet cats are kept exclusively indoors, or with secure outdoor access (e.g., cat enclosures, secure gardens), with FIV testing of any in-contact cats. All animal holding facilities should aim to individually house adult cats to limit the spread of FIV infection in groups of animals that are stressed and do not have established social hierarchies. Point-of-care (PoC) FIV antibody tests are available in Australia and NZ that can distinguish FIV-infected and uninfected FIV-vaccinated cats (Witness™ and Anigen Rapid™). Although testing of whole blood, serum or plasma remains the gold standard for FIV diagnosis, PoC testing using saliva may offer a welfare-friendly alternative in the future. PCR testing to detect FIV infection is not recommended as a screening procedure since a negative PCR result does not rule out FIV infection and is only recommended in specific scenarios. Australia and NZ are two of three countries where a dual subtype FIV vaccine (Fel-O-Vax® FIV) is available and offers a further avenue for disease prevention. Since FIV vaccination only has a reported field effectiveness of 56% in Australia, and possibly lower in NZ, FIV-vaccinated cats should undergo annual FIV testing prior to annual FIV re-vaccination using a suitable PoC kit to check infection has not occurred in the preceding year. With FIV-infected cats, clinicians should strive to be even more thorough than usual at detecting early signs of disease. The most effective way to enhance the quality of life and life expectancy of FIV-infected cats is to optimise basic husbandry and to treat any concurrent conditions early in the disease course. Currently, no available drugs are registered for the treatment of FIV infection. Critically, the euthanasia of healthy FIV-infected cats, and sick FIV-infected cats without appropriate clinical investigations, should not occur.

Retrospective cohort study of an outbreak of cryptosporidiosis caused by a rare Cryptosporidium parvum subgenotype.

The occurrence of a gastrointestinal illness among a class of 96 undergraduate veterinary students in New Zealand prompted laboratory and questionnaire-based investigations. Cryptosporidium parvum was the only enteropathogen identified in 4/7 faecal specimens analysed. The C. parvum isolates carried a rare IIa GP60 allele, indicating a point-source outbreak. The infection source could not be microbiologically traced, but the investigation suggested contact with calves during a practical class as the most likely exposure. A total of 25/80 respondents to a questionnaire were defined as cases using a clinical case definition (31% attack rate). The inferred median incubation period was 5 days (range 0-11 days), and the median illness duration was 5-6 days (range 2-23 days), corroborating previous observations in experimental cryptosporidiosis. Disease was self-limiting, characterized by abdominal discomfort, diarrhoea, and in some cases, vomiting. Originating from a rural area and having had previously handled ruminants were associated with a significant risk reduction in males. All the three students who reported chronic use of steroid inhalers for treatment of asthma were cases. This case highlighted, once again, the potential hazard for explosive outbreaks of cryptosporidiosis.

Recommendations on vaccination for Latin American small animal practitioners: a report of the WSAVA Vaccination Guidelines Group.

The World Small Animal Veterinary Association Vaccination Guidelines Group has produced global guidelines for small companion animal practitioners on best practice in canine and feline vaccination. Recognising that there are unique aspects of veterinary practice in certain geographical regions of the world, the Vaccination Guidelines Group undertook a regional project in Latin America between 2016 and 2019, culminating in the present document. The Vaccination Guidelines Group gathered scientific and demographic data during visits to Argentina, Brazil and Mexico, by discussion with national key opinion leaders, visiting veterinary practices and review of the scientific literature. A questionnaire survey was completed by 1390 veterinarians in five Latin American countries and the Vaccination Guidelines Group delivered continuing education at seven events attended by over 3500 veterinarians. The Vaccination Guidelines Group recognised numerous challenges in Latin America, for example: (1) lack of national oversight of the veterinary profession, (2) extraordinary growth in private veterinary schools of undetermined quality, (3) socioeconomic constraints on client engagement with preventive health care, (4) high regional prevalence of some key infectious diseases (e.g. feline leukaemia virus infection, canine visceral leishmaniosis), (5) almost complete lack of minimal antigen vaccine products as available in other markets, (6) relative lack of vaccine products with extended duration of immunity as available in other markets, (7) availability of vaccine products withdrawn from other markets (e.g. Giardia vaccine) or unique to Latin America (e.g. some Leishmania vaccines), (8) accessibility of vaccines directly by pet owners or breeders such that vaccination is not delivered under veterinary supervision, (9) limited availability of continuing education in veterinary vaccinology and lack of compulsion for continuing professional development and (10) limited peer-reviewed published scientific data on small companion animal infectious diseases (with the exception of leishmaniosis) and lack of support for such academic research. In this document, the Vaccination Guidelines Group summarises the findings of this project and assesses in evidence-based fashion the scientific literature pertaining to companion animal vaccine-preventable diseases in Latin America. The Vaccination Guidelines Group makes some recommendations on undergraduate and postgraduate education and academic research. Recognising that current product availability in Latin America does not permit veterinarians in these countries to vaccinate according to the global World Small Animal Veterinary Association guidelines, the Vaccination Guidelines Group makes a series of "pragmatic" recommendations as to what might be currently achievable, and a series of "aspirational" recommendations as to what might be desirable for the future. The concept of "vaccine husbandry" is addressed via some simple guidelines for the management of vaccine products in the practice. Finally, the Vaccination Guidelines Group emphasises the global trend towards delivery of vaccination as one part of an "annual health check" or "health care plan" that reviews holistically the preventive health care needs of the individual pet animal. Latin American practitioners should transition towards these important new practices that are now well embedded in more developed veterinary markets. The document also includes 70 frequently asked questions and their answers; these were posed to the Vaccination Guidelines Group during our continuing education events and small group discussions and should address many of the issues surrounding delivery of vaccination in the Latin American countries. Spanish and Portuguese translations of this document will be made freely available from the on-line resource pages of the Vaccination Guidelines Group.

Detection of papillomaviral DNA sequences in a feline oral squamous cell carcinoma.

Oral squamous cell carcinomas (OSCCs) are common and often fatal feline neoplasms. Factors that predispose to neoplasm development in cats are poorly defined. Around 25% of human OSCCs are caused by papillomaviruses (PVs). To determine if PVs are associated with OSCCs in cats, three sets of consensus primers were used to evaluate 20 feline OSCCs and 20 non-neoplastic feline oral lesions for the presence of PV DNA. Papillomaviral sequences were detected within one OSCC, but no non-neoplastic lesion. Sequencing of the amplified DNA revealed a previously unreported PV that was most similar to human PV type 76. This is the first time PV DNA has been amplified from the oral cavity of a cat. However, while these results suggest that feline gingival epithelial cells can be infected by PVs, they do not support a causal association between viral infection and the development of feline OSCCs.

Naturally occurring bacteriophages lyse a large proportion of canine and feline uropathogenic Escherichia coli isolates in vitro.

We investigated the feasibility of bacteriophage therapy to combat canine and feline Escherichia coli urinary tract infections (UTIs) by testing the in vitro lytic ability of 40 naturally occurring bacteriophages on 53 uropathogenic E. coli (UPEC). The mean number of UPEC strains lysed by an individual bacteriophage was 21/53 (40%, range 17-72%). In total, 50/53 (94%) of the UPEC strains were killed by one or more of the bacteriophages. Ten bacteriophages lysed 51% of UPEC strains individually and 92% of UPEC strains as a group. Electron microscopy and DNA sequencing of 5 'promising' bacteriophages revealed that 4 bacteriophages belonged to the lytic T4-like genus, while one displayed morphologic similarity to temperate P2-like bacteriophages. Overall, these results indicate that the majority of UPEC are susceptible to lysis by naturally occurring bacteriophages. Thus, bacteriophages show promise as therapeutic agents for treatment of canine and feline E. coli UTIs.

Feline uropathogenic Escherichia coli from Great Britain and New Zealand have dissimilar virulence factor genotypes.

We investigated the prevalence of 30 known virulence factor genes (VFGs) in uropathogenic E. coli (UPEC) from two geographically distinct feline populations, using a PCR-based approach. E. coli isolates were also subjected to macrorestriction analysis to assess their phylogenetic relationships. VFG profiles differed considerably according to the geographic origin of the isolates, enabling discriminant analysis to correctly predict population membership for 15/15 NZ isolates and 18/22 UK isolates. The prevalence of gene markers for P-fimbriae (PapA, PapC, PapEF, and PapG III), colicin V (CvaC), increased serum survival factor (Iss), complement resistance factor (TraT), pathogenicity-associated island (MalX), iron-regulated siderophore receptor (IreA) and haemolysin (HlyD) differed significantly between UK and NZ isolates. Significant phylogenetic differences between the two populations were also identified, but VFG profiles could not be predicted on the basis of phylogenetic relationships. Consequently, a geographically uneven distribution of certain virulence genes, independent of phylogeny, is the likely cause of VFG differences between populations. We cannot rule out that subtle differences in patient disease status may have contributed to the dissimilarity of VFG profiles.

Evidence that the large loss of glutathione observed in ischemia/reperfusion of the small intestine is not due to oxidation to glutathione disulfide.

Reperfusion injury following ischemia is thought to be the consequence of reactive oxygen species possibly generated either by xanthine oxidase activity or by processes associated with neutrophil activation in the affected organ or tissue. The conversion of xanthine dehydrogenase to the oxidase as well as the interactions between endothelium and neutrophils in the margination and activation of the latter are all considered to be results of conditions resulting from the ischemic episode. Determination of the redox status of glutathione in an ischemic/reperfused organ is frequently employed as an indicator of oxidative stress created by the production of oxygen free radicals during the reperfusion period. In this procedure, the ratio of oxidized glutathione (GSSG) to total glutathione (GSH + GSSG) is utilized to demonstrate the proportion of glutathione oxidized during reperfusion. We determined this ratio in the rat small intestine during ischemia and reperfusion and found that while the ratio of GSSG/(GSH + GSSG) does increase, this increase was the result of GSH disappearance rather than an increase in GSSG, and that essentially all of this loss occurred during the ischemic episode. We demonstrated that no oxidation of GSH occurred that was attributable to reperfusion per se; nor was there an increase of GSSG during this reoxygenation period.

A new model for inducing total hepatic ischemia while preventing circulatory collapse secondary to splanchnic vascular congestion.

Animal models used to study liver ischemia are limited by the lethal effect of splanchnic venous engorgement from portal triad occlusion (PTO). We compared a passive porto-systemic shunt (PSS) to a pump-driven PSS. The passive and pumped PSS groups (n = 6) received 60 min of PTO followed by 2 h of reperfusion. A control group received all interventions, but no PTO, and remained stable throughout. During PTO, severe circulatory shock with intestinal ischemia occurred in the passive group, while the pumped group remained stable. During reperfusion, both shunted groups experienced varying degrees of metabolic acidosis with decreases in cardiac index, stroke volume, superior mesenteric artery flow, and increases in systemic and intestinal vascular resistance. The mortality rate for the passive group was 83% vs. 0% for the pumped group. These results suggest that pumped PSS prevents splanchnic engorgement and allows for reproducible, isolated total hepatic ischemia in vivo.

Canine antibody response to Blastomyces dermatitidis WI-1 antigen.

OBJECTIVE: To assess whether dogs with blastomycosis produce antibodies against the WI-1 and A-antigens of Blastomyces dermatitidis and whether the antibodies are useful in serodiagnosis. SAMPLE POPULATION: 359 serum samples obtained from 245 dogs. PROCEDURE: 233 samples from 122 dogs with blastomycosis, and 1 sample each from 24 dogs with suspected blastomycosis, 51 control dogs without infection, and 48 healthy dogs from an enzootic region were obtained. Antibodies against WI-1 antigen were detected by radioimmunoassay (RIA). Serum samples were tested in parallel for antibodies against the A-antigen of B dermatitidis by commercial agar-gel immunodiffusion (AGID) in a reference laboratory. RESULTS: Antibodies were detected in 92% of infected dogs by RIA and in 41 % by AGID. For 29 serum samples that were obtained 11 to 1,545 days after diagnosis, antibodies were detected in 92% of samples by RIA and 7% by AGID. For 93 serial serum samples from 29 dogs with blastomycosis, the mean anti-WI-1 titer was 1:18,761 at the time of diagnosis, and decreased to a mean of 1:1,338 by 210 days after treatment was initiated. Of 24 dogs with suspected infection, antibodies were detected in 67% by RIA and 33% by AGID. Control dogs without blastomycosis had no detectable antibodies in either assay. Thus, sensitivity was 92% for RIA and 41 % for AGID, and specificity was 100% for both tests. CONCLUSIONS AND CLINICAL RELEVANCE: Anti-WI-1 antibodies are readily detected by RIA in dogs with blastomycosis. Titers become high, decline during treatment, and persist for months. Anti-A antibodies are sometimes detected with AGID, but these decrease quickly.

A serological survey of leptospiral antibodies in dogs in New Zealand.

AIM: To investigate the prevalence of titres to four endemic leptospiral serovars in dog sera from the lower half of the North Island, and the South Island of New Zealand submitted to diagnostic laboratories, and to explore the association between the prevalence of seropositive samples to leptospirosis and breed group, age group and sex. METHODS: Serum samples from 655 dogs residing in the central and lower North Island and from the South Island of New Zealand were sourced from the Massey University Veterinary Teaching Hospital and from submissions to New Zealand Veterinary Pathology in 2005. They were screened by the Microscopic Agglutination Test (MAT) against Leptospira interrogans serovars Copenhageni and Pomona and L. borgpetersenii serovars Hardjo and Ballum. Titres greater or equal to 96 were considered positive. Variables investigated for their association with the prevalence of seropositive samples to leptospirosis included serovar, breed, North vs. South Island, age and sex. RESULTS: Positive MAT titres to Leptospira interrogans serovar Copenhageni were found in 10.3 % of dogs (95% CI=8.1-12.9), and were more common than positive titres to other leptospiral serovars. Small breeds did not have a lower prevalence of Copenhageni titres than other breeds. Positive titres to Leptospira borgpetersenii serovar Hardjo were associated with breeds of dogs used as farm working dogs. There was no significant difference in the prevalence of positive leptospiral titres between dogs from the North or South Islands. Dogs greater than 12 years of age were less likely to have positive titres to Leptospira than younger dogs. No association was found between positive titres and sex. CONCLUSIONS: Breeds of dogs used as farm working were at greater risk of exposure to Leptospira borgpetersenii serovar Hardjo. Small breeds did not have a lower risk of seropositivity to Copenhageni than farm working breeds. Further study should be undertaken to confirm the prevalence of positive titres to leptospirosis in farm dogs and dogs resident in the South Island. CLINICAL RELEVANCE: The risk of dogs being exposed to Leptospira interrogans serovar Copenhageni, and requirement for vaccination against serovar Copenhageni, cannot be determined by geographical location or breed group. Vaccination against Leptospira borgpetersenii serovar Hardjo is likely to be beneficial in working dogs.

Alpha and gamma herpesvirus detection in two herds of farmed red deer (Cervus elaphus) in New Zealand.

CASE HISTORY: In September 2004 two hinds on Farm 1 were observed with epiphora and keratoconjunctivitis, and corneal scarring. A low pregnancy rate in some hinds had been recorded that year. In the same year six yearling deer were observed on Farm 2 with keratitis, uveitis and corneal scarring. CLINICAL AND PATHOLOGICAL FINDINGS: On Farm 1, conjunctival swabs and blood samples were collected from the hinds with ocular lesions, and from 24 other hinds. The two affected hinds were immunosuppressed with dexamethasone for 7 days. Conjunctival, nasal and vaginal swabs were collected daily before euthanasia and necropsy on the eighth day. Subsequently, another five non-pregnant hinds were similarly immunosuppressed and necropsied, and the reproductive tracts of 20 non-pregnant hinds were collected following slaughter. Semen samples were collected from four stags implicated with reproductive failure. On Farm 2, conjunctival swabs were collected from six hinds with ocular lesions and from 14 unaffected deer. Viral culture, consensus primer PCR and sequencing for specific herpesviruses was carried out on conjunctival swabs, buffy coat from blood samples, semen and reproductive tracts. Necropsy samples were also examined using gross pathology and histopathology. On Farm 1, a type 2 rhadinovirus (CvRhV) was detected in the conjunctiva of one hind with keratoconjunctivitis using PCR. Following immunosuppression, gross vesicular and histological vaginal lesions typical of infection with alphaherpesvirus were observed in samples of vaginal tissue from the same hind. Buffy coat, vaginal and lumbar spinal nervous tissues were also positive for cervid herpesvirus 1 (CvHV-1) using PCR. Herpesviruses were not detected in reproductive tracts, ocular or semen samples of the other deer. CvRhV was detected in buffy coats from four other hinds and in a conjunctival swab from one hind, all without ocular lesions, using PCR. On Farm 2, conjunctival swabs from two deer with keratitis were culture positive for CvHV-1. Two culture-negative conjunctival samples from deer without ocular lesions were positive for CvHV-1 by PCR. In two other affected animals, presence of CvRhV was confirmed by PCR and sequencing. DIAGNOSIS: Infection with CvHV-1 associated with keratitis and vulvovaginitis, and CvRhV infection in deer with and without ocular lesions. CLINICAL RELEVANCE: CvHV-1 is a likely cause of keratoconjunctivitis and possibly reproductive tract pathology in deer. Investigation of ocular lesions and reproductive failure in farmed deer should include CvRhV and CvHV-1.

Use of polymerase chain reaction for the differentiation of Group A bovine rotavirus G6, G8, and G10 genotypes in the North Island of New Zealand.

AIM: To determine the presence of Group A rotavirus G6, G8, and G10 genotypes in calves in the North Island of New Zealand. METHODS: Faecal samples from 730 calves (<6 weeks old) with diarrhoea were collected during 2006 and 2007 from seven regions in the North Island of New Zealand. The samples were screened for the presence of Group A rotavirus antigen, using a commercial ELISA. Forty-one samples from different farms were randomly selected out of the 385 ELISA-positive samples and tested using PCR for the presence of G6, G8, and G10 genotypes of rotavirus. RESULTS: The PCR analysis of 41 antigen-positive field samples revealed that 37 (90%) contained genotype G6, three (7%) genotype G10, one sample (2%) had both G6 and G10 genotypes, and none contained genotype G8. CONCLUSIONS: Rotavirus genotype G6 was the predominant genotype found in this preliminary study and was present in all seven regions studied. Genotype G10 was also found in some regions of the North Island, whereas genotype G8 was not found in any sample. CLINICAL RELEVANCE: This is the first report on rotavirus G genotypes present in calves in the North Island of New Zealand.

Probable malignant catarrhal fever presented as transient generalised crusting dermatitis in a cow.

CASE HISTORY: A 2-year-old crossbred cow developed crusting ulcerative lesions that covered approximately 40% of the body. They were first observed 2 weeks after the cow calved, and were most severe over the caudal aspect of the proximal hindlegs and perineum. CLINICAL FINDINGS AND DIAGNOSIS: Generalised variably confluent 1-2-cm diameter foci of ulceration and crusting were visible. No ocular or oral lesions were visible, and the cow did not have diarrhoea. Skin biopsies revealed lesions consistent with those previously described for malignant catarrhal fever (MCF). Additionally, prominent multinucleate cells were visible. The DNA for ovine herpesvirus type 2 (OHV-2) was amplified from the skin biopsies, using PCR. The cow spontaneously made a complete clinical recovery. CLINICAL RELEVANCE: Malignant catarrhal fever should be considered in cases of ulcerative skin disease in cattle. The disease is difficult to diagnose, and a combination of skin histology as well as PCR is required. Although probably rare, it appears complete recovery from MCF is possible when the disease is confined to the skin.

Feline cutaneous viral papilloma associated with human papillomavirus type 9.

A 12-year-old domestic Shorthaired cat developed a multinodular exophytic mass on the dorsal surface of the nose. The skin surrounding the mass was nonpigmented, and actinic keratosis had been diagnosed in this area 3 years previously. Histologic examination revealed hyperkeratosis, epidermal hyperplasia, papillomatosis, koilocytosis, and possible intranuclear viral inclusions. Polymerase chain reaction amplified papillomaviral deoxyribonucleic acid from formalin-fixed samples of the lesion. Sequencing of the amplicon revealed 98% similarity to human papillomavirus (HPV) type 9. To the authors' knowledge, this is only the second reported feline cutaneous viral papilloma. In addition, this is the first report of a feline papilloma being associated with an HPV.

Multivariate analysis of risk factors for feline hyperthyroidism in New Zealand.

AIM: To search for putative risk factors for feline hyperthyroidism in New Zealand, using a case-control study. METHODS: A questionnaire-based case-control study involving the owners of 375 cats in New Zealand (125 hyperthyroid cats, 125 randomly selected control cats, and 125 age- and sex-matched control cats) was conducted to examine associations between potential risk factors and occurrence of feline hyperthyroidism. Data were collected between December 1996 and February 1998, relative to cat and owner demography and medical history, cats' indoor and outdoor environments, and cats' diets. A range of statistical techniques was employed to analyse the data, including descriptive analyses, univariate logistic regression for each variable and multivariate stepwise forward logistic regression. RESULTS: Multivariate analysis revealed that affected cats were more likely to be female (odds ratio (OR)=3.3; 95% confidence interval (CI)=1.2-9.0) and older than unaffected random control cats. Purebred cats were at a much lower risk of being diagnosed as hyperthyroid than were domestic short- and long-haired cats (OR=0.01; 95% CI=0.001-0.20). If more than one cat was present in a household, hyperthyroidism was less likely to be identified (OR=0.15; 95% CI=0.05-0.44) compared with single-cat households. Hyperthyroid cats were 6.6 times more likely (95% CI=1.8-23.9) to be reported to sleep predominantly on the floor than control cats. Cats whose bedding was regularly treated with anti-flea products appeared to be at a considerably higher risk for hyperthyroidism (OR=57.6; 95% CI=3.8-->200); and, to a lesser extent, so were cats living in households where fly sprays were reported to be used regularly (OR=3.3; 95% CI=1.2-9.3). The interaction between drinking water from puddles and regular use of organic garden fertilisers, such as compost or animal manure, was associated with a 5.3-fold (95% CI=1.1-25.6) increase in the risk of cats being diagnosed with the disease. Hyperthyroid cats were twice as likely (95% CI=0.3-12.9) to have eaten at least half of their daily food requirements as canned commercial cat food compared with unaffected cats. Cats exposed to a variety of flavours of canned cat food were more likely to be diagnosed with hyperthyroidism than were those fed only one flavour (OR=3.8; 95% CI=1.5-9.6). The presence of dental disorders was associated with a 5.5-fold increase in the risk of being diagnosed as hyperthyroid and this association was independent of the cat's age (95% CI=1.7-17.5). CONCLUSIONS: The results of this study support and extend those in several earlier reports and show that cats in New Zealand are, in many respects, similar to cats in Europe and North America in terms of their susceptibility to hyperthyroidism. The finding that female cats are predisposed to hyperthyroidism is at variance with most previously published work. It remains unclear which, if any, of the identified disease associations are causal, so further studies of this increasingly prevalent feline endocrinopathy are warranted.