Urinalysis in dog and cat: A review

Chemical Sensors and Biosensors for Point-of-Care Testing of Pets: Opportunities for Individualized Diagnostics of Companion Animals

Point-of-care testing (POCT) is recognized as one of the most disruptive medical technologies for rapid and decentralized diagnostics. Successful commercial examples include portable glucose meters, pregnancy tests, and COVID-19 self-tests. However, compared to advancements in human healthcare, POCT technologies for companion animals (pets) remain significantly underdeveloped. This Review explores the latest advancements in pet POCT and examines the challenges and opportunities in the field for individualized diagnostics of cats and dogs. The most frequent diseases and their respective biomarkers in blood, urine, and saliva are discussed. We examine key strategies for developing the next-generation POCT devices by harnessing the potential of selective (bio)receptors and high-performing transducers such as lateral flow tests and electrochemical (bio)sensors. We also present the most recent research initiatives and the successful commercial pet POCT technologies. We discuss future trends in the field, such the role of biomarker discovery and development of wearable, implantable, and breath sensors. We believe that advancing pet POCT technologies benefits not only animals but also humans and the environment, supporting the One Health approach.

Dried Whole Black Soldier Fly Larvae Consumption Supports Gestation, Lactation, and Growth in Cats

This study evaluated the consumption of dried whole black soldier fly larvae (DBSFL) to meet the nutritional requirements of gestating and lactating cats and their kittens post-weaning. Queens (n = 8/treatment) were randomly assigned to a control diet or diets containing 20% DBSFL through gestation and lactation. Weaned kittens (n = 8/treatment) were maintained on their dams' diet for 10-weeks. There were no differences (p > 0.05) in the litter size, dietary intake, body weight, or fecal quality of the queens during the trial. The kittens receiving the DBSFL diet consumed more on an absolute or caloric basis than those fed the control diet at week 5 (p = 0.1) and week 10 (p = 0.03) and had higher body weights at weeks 6 through 10 (p < 0.05). The blood and urinalysis parameters were generally within normal ranges, with some variations observed between treatments that were not considered biologically significant. The dry matter, crude protein, and amino acid digestibility levels were higher in kittens fed the DBSFL diet (p = 0.05). These data are the first to demonstrate the safety and efficacy of DBSFL for the gestation and lactation of queens and for the growth of kittens, as well as its suitability in diets for cats of all life stages.

Safety and Digestibility of a Novel Ingredient, Brewed Lamb Protein, in Healthy Adult Dogs

Protein production through precision fermentation is an attractive option to reduce animal use in food production. This study focused on the safety and digestibility of food containing a test ingredient, brewed lamb protein (Saccharomyces cerevisiae expressing a lamb protein), at inclusion levels of 0% (control), 15%, 30%, or 40% were evaluated over 182 days in 40 dogs. No significant differences in body weight, body condition score, body composition, physical examination, food intake, or urinary parameters were observed among groups. Hematological and serum biochemical parameters were within reference ranges and were largely similar among groups. Levels of chloride, cholesterol, and homocysteine were significantly lower at some time points in dogs fed the test ingredient foods compared with the control food, but all remained within reference ranges. Whole blood taurine levels indicated no deficiency. Alanine aminotransferase levels were above the normal range at Day 177 in dogs in the control and 15% test ingredient groups. Fecal score was slightly decreased in dogs fed the 30% or 40% test ingredient foods, and fecal pH was decreased in dogs fed any of the test ingredient foods. Digestibility of most parameters was similar among foods, but apparent fat digestibility was significantly lower in foods with the test ingredient. Overall, these results indicate that the test ingredient is safe for use in dog food.

RENAL FUNCTION PARAMETERS OF HEALTHY CAPTIVE AND SEMICAPTIVE AMAZONIAN MANATEES (TRICHECHUS INUNGUIS)

Evaluating renal function is essential for managing captive wild animals, particularly threatened species like the Amazonian manatee (Trichechus inunguis) in rehabilitation and prerelease programs. A series of urine diagnostic tests, such as gross appearance, semiquantitative chemical analyses, microscopic review of sediments, and quantitative analyses of urea and creatinine, were performed in 57 free-catch urine samples. On the same occasion, 52 serum samples from the same individuals were analyzed for creatine kinase activity, creatinine, blood urea nitrogen, albumin, sodium, potassium, and chloride concentrations; serum symmetric dimethylarginine (SDMA) was measured for the first time in the species. Females had higher urine creatinine concentration (21.7 ± 11.8 mg/dl) and specific gravity (1.003 ± 0.003 mg/dl) than males (11.9 ± 8.5 mg/dl and 1.001 ± 0.002 mg/dl) (P < 0.01 for both). Males presented higher urine creatinine:urea ratio than females (24.8 ± 29.2 and 20.5 ± 29.2, respectively) (P < 0.05). Urine pH was lower in manatees from the semicaptive area (7.8 ± 0.6) than in manatees under human care (8.5 ± 0.6) (P = 0.02) using the benchtop pH meter but showed no difference between areas in the dipstick reaction (P = 0.71), given its lower sensitivity and narrower range detection. Furthermore, 18 and 75% of urine samples were positive for the presence of blood and/or nitrite, respectively, in the dipstick reaction, possibly because of sample contamination. Significant correlation was observed between serum blood urea nitrogen and urine urea concentrations (P = 0.02), and between serum and urine creatinine concentrations (P = 0.01). Serum SDMA did not differ between sex or between captive and semicaptive individuals. However, it positively correlated with urine (P = 0.02) and serum creatinine (P = 0.01) demonstrating its potential as a bioindicator of kidney function. The renal function of Amazonian manatees can be effectively assessed by urinalysis, especially when combined with serum biochemistry.

CYSTOCENTESIS AND URINALYSIS IN ZOOMEDICINE: AN UNDERESTIMATED TOOL FOR LARGE FELID STANDARD HEALTH CHECKS

Chronic kidney disease (CKD) is a prevalent disease among felids; yet its origin is still poorly understood, and the disease often remains asymptomatic for years, underscoring the need for early diagnosis. This study aimed to investigate the diagnostic value of urinalysis in accurately staging CKD, particularly as routine health checks in large felids often overlook its significance. In this research, ultrasound-guided cystocentesis (UGC) was performed on 50 captive nondomestic felids during routine veterinary health checks under general anesthesia. Urinalysis included microscopic examination of the sediment, measurement of urine specific gravity (USG) and protein to creatinine ratio (UPC). Additional serum kidney markers, such as creatinine and symmetric dimethylarginine, were compared with USG and UPC to assess their diagnostic value as urinary biomarkers. The results demonstrated proteinuria (UPC > 0.4) or borderline proteinuria (UPC 0.2-0.4) in 49% of the animals. Among these cases, 62% were of renal origin, and 38% were postrenal causes. USG was significantly higher in felids with borderline proteinuria compared to those with proteinuria. A moderate, but significant negative correlation between serum parameters and USG was observed, emphasizing the importance of assessing both diagnostic parameters during kidney evaluations. Additionally, felids with CKD have an increased risk of urinary tract infections, necessitating microscopic urinalysis and bacterial culture analysis. Abnormalities, including hematuria, pyuria, crystalluria, and bacteriuria, were found in approximately 38% of cases through microscopical examination of urine. No complications associated with UGC were observed and abnormal findings were detected in 60% of the cases. Based on these results, the authors recommend the inclusion of UGC and urinalysis as standard diagnostic tools in general health checks for nondomestic felids. This approach provides valuable insights into the early detection and staging of CKD, supporting early intervention and supportive medical care to prolong renal health in these animals.

Urinalysis and culture results of free-catch urine samples in dogs: a randomised controlled trial

OBJECTIVES

To evaluate the prevalence of bacterial presence in free-catch urine samples preceded by either a standardised prepped ("clean-catch") protocol versus unprepped (non-cleaned) voiding.

MATERIALS AND METHODS

The study was a single-centre prospective single-blinded randomised controlled trial. Urine samples were obtained from 100 client-owned dogs presenting for routine evaluation. Dogs were randomly assigned to either the prepped group (preputial or peri-vulvar area cleaned with sterile saline before collection) or the unprepped group (no preliminary cleansing) stratified by sex. Urinalysis and urine culture (blood and MacConkey agar) were performed on all samples. Significant bacterial presence on urine culture was defined as >104 colony forming units (CFU)/mL.

RESULTS

There were no statistically significant associations between prepped versus unprepped collection method or sex with a urinalysis positive for bacteriuria. However, on culture, significant bacterial growth was almost five times more likely to be associated with males relative to females (odds ratio 4.59, 95% confidence interval 1.61 to 13.10). The probability of finding a positive culture was not statistically associated with prep method (odds ratio 1.43, 95% confidence interval 0.50 to 4.08).

CLINICAL SIGNIFICANCE

For the majority of dogs without clinical signs of urinary tract infection, free-catch urine collection does not result in significant bacteriuria found on analysis or culture. The presence of bacteria found in free-catch samples may be secondary to sample contamination or subclinical bacteriuria. Sample contamination or subclinical bacteriuria may be more prevalent in male dogs.

Short-term Effects of Surgical Sterilization on Urinary PH and Specific Gravity, Blood Urea Nitrogen, Serum Creatinine, and Urinary Protein to Creatinine Ratio in Sexually Intact Male and Female Dogs

Surgical sterilization is a widely accepted method to reduce the birth of unwanted dogs and reducing the incidence of reproductive diseases. However, the sterilization of domestic dogs has generated debate among veterinarians and owners about its effects on urinary parameters. The purpose of this study was to evaluate the short-term effects of surgical sterilization on urinary parameters in healthy adult sexually intact male and female dogs. Ten healthy adult sexually intact mongrel dogs (5 males and 5 females) weighing 15 to 20 kg participated in this study. Only those dogs which were at least 1yearold included in this study to ensure that they had reached sexual maturity. If a dog's urine sample is abnormally colored or milky, has a pH greater than 7.5, and a positive bacterial culture is confirmed, the dog will be excluded. Physical, CBC, and biochemical examinations, such as measurement of blood urea nitrogen (BUN) and serum creatinine (Cr) concentrations and urinalysis (including determination of urine pH and specific gravity (USG) measurement, calculation of the urine protein/ creatinine ratio (UPC), and dipstick evaluation) were performed on each dog. At least 15 days after the sterilization surgery, the dogs underwent physical examination, CBC, biochemistry, and urinalysis at least 15 days later. Urine samples were collected by cystocentesis and stored at 4°C for analysis. After centrifugation at 3000 g for 5 minutes, the urinalysis was performed within 4 hours of collection. There were no significant differences (P>0.05) between the mean BUN and Cr, UPC, USG, and urine pH before and after ovariohysterectomy and castration. The study found that castration and ovariohysterectomy did not affect short-term urinary parameters in healthy adult sexually intact male and female dogs. However, it is uncertain how sterilization affects urinalysis results in sexually intact dogs, and more research with larger sample sizes is needed to determine the impact.

Clinical management of feline chronic kidney disease in Portugal: a questionnaire-based study

OBJECTIVES

The aim of the study was to characterise the clinical management of feline chronic kidney disease (CKD) by veterinary practitioners in Portugal.

METHODS

A questionnaire-based study was designed to be completed by all veterinarians who had diagnosed and treated at least one case of feline CKD in the previous year.

RESULTS

A total of 409 veterinary practitioners responded to the questionnaire, with approximately half of them diagnosing 2-5 cases of feline CKD per month (n = 219, 53.5%). Although a high proportion of these reported using the guidelines published by the International Renal Interest Society (n = 379, 92.7%), only 19.1% (n = 78) systematically performed systolic blood pressure (SBP) measurements in all of their patients. A renal diet was advised by almost all respondents (n = 406, 99.3%), but 36.9% (n = 150) of them considered that it represented less than 75% of the daily food intake for most of their patients. This dietary intervention was often prescribed regardless of stage (n = 298, 73.4%) and without a proper gradual diet transition. Appetite stimulants were frequently prescribed (n = 366, 89.5%), as well as a calcium channel blocker (n = 171, 41.8%) and an angiotensin-converting enzyme inhibitor (n = 245, 59.9%) to control systemic hypertension and proteinuria, respectively. Prescription of a phosphate binder was also common (n = 311, 76.0%). Regarding monitoring, 70.9% (n = 290) recommended that stable patients be reassessed every 2-3 months or more frequently, but only 35.7% (n = 146) were able to comply with this periodicity due to owners' constraints.

CONCLUSIONS AND RELEVANCE

The findings showed that although most survey respondents are aware of international guidelines for the clinical management of cats with CKD, the SBP measurement still needs to be more systematic to allow proper substaging and detection of systemic hypertension. The monitoring frequency was lower than recommended. Furthermore, the introduction of a renal therapeutic diet should be refined to improve its acceptance rate.

Longitudinal examination of urine pH, specific gravity, protein, culture, and antimicrobial resistance profiles in healthy dogs

BACKGROUND

Urine is routinely evaluated in dogs to assess health. Reference ranges for many urine properties are well established, but the scope of variation in these properties over time within healthy dogs is not well characterized.

OBJECTIVES

Longitudinally characterize urine properties in healthy dogs over 3 months.

ANIMALS

Fourteen healthy client-owned dogs.

METHODS

In this prospective study, dogs were evaluated for health; then, mid-stream free-catch urine was collected from each dog at 12 timepoints over 3 months. Urine pH, urine specific gravity (USG), protein, cultures, and antimicrobial resistance profiles were assessed at each timepoint.

RESULTS

Urine pH varied within and between dogs over time (Friedman's test: within P = .03; between P < .005). However, USG, protein, and bacterial diversity of urine were consistent within dogs over time, and only varied between dogs (Kruskal-Wallis: between all P < .005). Antimicrobial resistant isolates were identified in 12 out of 14 dogs with 34 of 48 of the isolates demonstrating resistance to amoxicillin.

CONCLUSIONS AND CLINICAL IMPORTANCE

Urine pH should be assessed at multiple timepoints via pH meter before making clinical decisions. Mid-stream free-catch urine with high concentrations of bacteria (>105  CFU/mL) should not be considered the only indicator of urinary tract infection. Bacterial isolates from dogs in this study had widespread resistance to amoxicillin/oxacillin underscoring the need for antimicrobial stewardship.

Urine protein quantification in human urine on boron-doped diamond electrodes based on the electrochemical reaction of Coomassie brilliant blue

Urinalysis is attracting interest in personal healthcare management as part of a general move to improve quality of life. Urine contains various metabolites and the protein level in urine is an indicator of kidney function. In this study, a novel electrochemical sensing system based on boron-doped diamond (BDD) electrodes was developed for the detection of protein concentrations in human urine. BDD electrodes have the advantages of a wide electrochemical potential window and low non-specific adsorption, making them ideal for simple, rapid, and compact devices for home detection of bio-relevant substances. Coomassie brilliant blue (CBB), a dye that selectively and strongly binds to urine proteins, was found to be a redox-active indicator to show a decrease in its redox currents in relation to the concentration of protein in urine samples. Our detailed studies of BDD electrodes showed their limit of detection to be 2.57 μg mL-1 and that they have a linear response that ranges from 0 to 400 μg mL-1 in urine samples. We also investigated the detection of urine protein in different urine samples. Our results agreed with those obtained using conventional colorimetric analysis. We believe this to be the first study of electrochemical detection of urine protein in urine samples on BDD electrodes, which is of great significance to be able to obtain results with electrical signals rapidly compared to conventional colorimetric analysis. This CBB-BDD technique has the potential to assist healthcare management in the form of a rapid daily diagnostic test to judge whether a more detailed examination is needed.

Comparative Evaluation between Visual and Automated Dipstick Urinalyses in Dogs

Urine test strips are commercially available and can be assessed with semi-automated analyzers or by visual assessment. This study aimed to compare the visual and automated evaluations of dipstick variables in canine urine samples. One hundred and nineteen urine samples were evaluated. Automated analysis was performed on a veterinary urine analyzer URIT-50Vet (URIT Medical Electronic) with UC VET13 Plus strips. Multistix 10 SG dipsticks (Siemens Healthcare GmbH, Erlangen, Germany) were used for visual evaluation, along with a refractometer (Clinical Refractometer Atago T2-Ne, Atago Co., Tokyo, Japan) for urine specific gravity measurements. A linear relationship was observed between the pH measurements (p = 0.2) of the two methods; the Passing-Bablok procedure was valid since neither proportional nor systematic significant errors were observed. Comparing the two methods, the correlation for urine specific gravity was poor (p = 0.01, CI 0.667-1.000). Moderate agreement was demonstrated for proteins (κ = 0.431), bilirubin (κ = 0.434) and glucose (κ = 0.450). Agreement was substantial for blood (κ = 0.620) and poor for leukocytes (κ = 0.100). Poor agreement was observed for ketones (κ = -0.006). Apart from the pH analysis, visual and automated dipstick urinalyses should not be used interchangeably. Multiple urine samples obtained from the same dog during the day should be evaluated using the same method to overcome erroneous results.

Pet dogs transfer veterinary medicines to the environment

Worldwide, the number of pet dogs increases yearly, and as a result so does the use of veterinary medicines for flea and tick control. We investigated the potential transfer of veterinary flea products from dogs to the environment in a 'proof of principle' experiment. For this purpose, samples of hair, urine, and water after swimming were investigated. Nine dogs were recruited for this study, eight of which had been recently treated with an ectoparasiticide product. Hair and urine samples were tested for afoxalaner, fluralaner, fipronil and imidacloprid. Interestingly, contamination with ectoparasiticides was frequently demonstrated in samples from dogs untreated with these particular substances, suggesting widespread secondary transfer. In addition, hair retrieved from a bird's nest contained fipronil, fluralaner and imidacloprid, indicating a potential pathway for the exposure of juvenile birds. Three of the dogs also participated in a swimming experiment. One had been treated with oral fluralaner, whilst the remaining two had received other compounds not included in our study. However, in all three dogs, both fluralaner and imidacloprid were detected in hair samples. Fluralaner concentrations in the swimming water exceeded Dutch water quality standards, indicating a potential risk to the aquatic environment. Imidacloprid levels increased after each swimming dog, but did not breach Dutch water quality standard levels. These findings all call for improvements in the current risk assessment and management for veterinary medicines, by including companion animals and their exposure pathways into ecosystems.

Hypertrophic osteodystrophy in dogs: diagnosis and treatment

Hypertrophic osteodystrophy is an uncommon orthopaedic disease that affects young, growing dogs. Aetiology is currently unknown; however, several unproven etiologies have been theorised in the literature including canine distemper virus, previous vaccination, hereditary causes and auto-immune disorders. Affected animals often present with varying degrees of lameness, lethargy, pyrexia and/or distal metaphyseal swelling of affected limbs. An index of suspicion is based on clinical signs. Confirmation is obtained with radiographs of the affected limb(s) by the presence of a "double physis," or a radiolucent line that is parallel to the physis. Treatment varies depending on degree affected, but generally consists of anti-inflammatory steroids, pain medications, gastrointestinal support, nutritional management and appropriate supportive care. Critically affected patients require intensive monitoring and more aggressive supportive care for prevention of life-threatening sequalae. Prognosis is very favourable with mildly and moderately affected patients, but good to guarded in severely affected patients.

Infections of the Urinary Tract of Bacterial Origin in Dogs and Cats

The diseases of the urinary tract in small animal medicine, especially in dogs and cats, occur frequently with different etiologies. The most common cause of urinary tract infections (UTIs) are bacteria which enter upwards through the urethral opening. UTIs occur in hosts with compromised defence mechanisms in which the virulent microbes can adhere, multiply and persist in the urinary tract. In addition to bacteria, also viruses or fungi may infect the urinary tracts. Bacterial infection can develop in the upper (kidneys and ureters) or lower (bladder, urethra) urinary tract and are manifested by various clinical signs such as: frequent or difficult and painful urination, presence of blood in the urine, or its foul odour. The symptoms in sick animals are often accompanied by fever, discomfort, and loss of appetite. The UTIs in dogs and cats are caused by both Gram-negative (e. g. Escherichia coli, Pseudomonas aeruginosa, Klebsiella spp., Proteus spp.) and Gram-positive (e. g. Staphylococcus spp., Streptococcus spp., and Enterococcus spp.) bacteria. The properly performed aseptic sampling of the urine is one of the most important steps in bacteriological diagnostics. In this study, 105 urine samples were collected from dogs and cats. The cultivation, microscopy and biochemical examinations were used for species identification. Finally, the bacteriological examination included also determining the susceptibility of pathogens against antibiotics by the disc-diffusion method. The results were processed and expressed as a percentage according to identified pathogens, animal species, sex, breed and age. The uropathogens were diagnosed mainly in males aged 7—10 years. The most commonly identified pathogens were Escherichia coli, Streptococcus spp. and Staphylococcus spp. Tests of bacterial susceptibility to antibiotics showed that enrofloxacin, cefotaxime, and cephazolin were the most effective against uropathogens.