Elizabeth M. Lund

Epidemiology of surgical castration of dogs and cats in the United States

OBJECTIVE To estimate the prevalence of surgical castration among dogs and cats evaluated at private US veterinary hospitals and to determine the influence of sex, age, breed, geographic location, and prepaid wellness plan enrollment on the likelihood of castration. DESIGN Retrospective period prevalence study. ANIMALS 320,172 cats and 1,339,860 dogs examined at 651 hospitals during 2007 Procedures-Univariate and multivariate analyses were used to compare prevalence among subpopulations for each species. RESULTS The overall prevalence of castration was 82% in cats and 64% in dogs. Prevalence increased significantly with age in both species. Among cats, males were slightly more likely to be castrated than females (prevalence ratio [PR] = 1.03) and mixed breeds slightly less likely than purebreds (PR = 0.99). Among dogs, males were less likely to be castrated than females (PR = 0.93) and mixed breeds more likely than purebreds (PR = 1.19). Prevalence was lowest in dogs in the Southeastern United States (61%). Dogs and cats on a wellness plan were more likely to be castrated than those not on a plan (PR = 1.33 and 1.18, respectively). Among commonly reported dog breeds, pit bull-type dogs (27%) and Chihuahuas (46%) were least likely to be castrated. CONCLUSIONS AND CLINICAL RELEVANCE Many young adult (1- to < 4-year-old) dogs (32%) were uncastrated, signaling a need to promote earlier castration. Outreach efforts should be directed toward owners of pets least likely to be castrated, such as male dogs, dogs of specific breeds (ie, pit bull-type and Chihuahua), and dogs in the Southeastern United States. Additional research is needed to evaluate the potential impact of wellness programs on an owners decision to have his or her pet castrated.

Risk factors associated with the development of chronic kidney disease in cats evaluated at primary care veterinary hospitals

OBJECTIVE To identify risk factors associated with diagnosis of chronic kidney disease (CKD) in cats. DESIGN Retrospective case-control study. ANIMALS 1,230 cats with a clinical diagnosis of CKD, serum creatinine concentration > 1.6 mg/dL, and urine specific gravity < 1.035 and 1,230 age-matched control cats. PROCEDURES Data on putative risk factors for CKD were extracted for multivariate logistic regression analysis from the medical records of cats brought to 755 primary care veterinary hospitals. For a subset of cats evaluated 6 to 12 months prior to the date of CKD diagnosis or control group inclusion, the percentage change in body weight between those dates as well as clinical signs at the earlier date were analyzed for associations with CKD development. RESULTS Risk factors for CKD in cats included thin body condition, prior periodontal disease or cystitis, anesthesia or documented dehydration in the preceding year, being a neutered male (vs spayed female), and living anywhere in the United States other than the northeast. The probability of CKD decreased with increasing body weight in nondehydrated cats, domestic shorthair breed, and prior diagnosis of diabetes mellitus and increased when vomiting, polyuria or polydipsia, appetite or energy loss, or halitosis was present at the time of diagnosis or control group inclusion but not when those signs were reported 6 to 12 months earlier. Median weight loss during the preceding 6 to 12 months was 10.8% and 2.1% in cats with and without CKD, respectively. CONCLUSIONS AND CLINICAL RELEVANCE The probability of CKD diagnosis in cats was influenced by several variables; recent weight loss, particularly in combination with the other factors, warrants assessment of cats for CKD.

Risk factors associated with calcium oxalate urolithiasis in dogs evaluated at general care veterinary hospitals in the United States.

Calcium oxalate urolithiasis results from the formation of aggregates of calcium salts in the urinary tract. Difficulties associated with effectively treating calcium oxalate urolithiasis and the proportional increase in the prevalence of calcium oxalate uroliths relative to other urolith types over the last 2 decades has increased the concern of clinicians about this disease. To determine factors associated with the development of calcium oxalate urolithiasis in dogs evaluated at general care veterinary hospitals in the United States, a retrospective case-control study was performed. A national electronic database of medical records of all dogs evaluated between October 1, 2007 and December 31, 2010 at 787 general care veterinary hospitals in the United States was reviewed. Dogs were selected as cases at the first-time diagnosis of a laboratory-confirmed urolith comprised of at least 70% calcium oxalate (n=452). Two sets of control dogs with no history of urolithiasis diagnosis were randomly selected after the medical records of all remaining dogs were reviewed: urinalysis examination was a requirement in the selection of one set (n=1808) but was not required in the other set (n=1808). Historical information extracted included urolith composition, dogs diet, age, sex, neuter status, breed size category, hospital location, date of diagnosis, and urinalysis results. Multivariable analysis showed that the odds of first-time diagnosis of calcium oxalate urolithiasis were significantly (P<0.05) greater for dogs<7 years, males (OR: 7.77, 95% CI: 4.93-12.26), neutered (OR: 2.58, 1.44-4.63), toy- vs. medium-sized breeds (OR: 3.15, 1.90-5.22), small- vs. medium-sized breeds (OR: 3.05, 1.83-5.08), large- vs. medium-sized breeds (OR: 0.05, 0.01-0.19), and those with a diagnosis of cystitis within the previous year (OR: 6.49, 4.14-10.16). Urinary factors significantly associated with first-time diagnosis of calcium oxalate urolithiasis were acidic vs. basic pH (OR: 1.94, 1.22-3.10), presence of RBCs (OR: 6.20, 3.91-9.83) or WBCs (OR: 1.62, 1.03-2.54), and protein concentration>30 mg/dL (OR: 1.55, 1.04-2.30). Patient demographics and urinalysis results are important factors that can support risk assessment and early identification of canine oxalate urolithiasis. Therefore, periodic urolith screening and monitoring of urine parameters should be encouraged for dogs at risk of developing these uroliths.

Effect of age at gonadectomy on the probability of dogs becoming overweight

OBJECTIVE To determine whether gonadectomy or age at gonadectomy was associated with the risk that dogs would subsequently become overweight. DESIGN Retrospective cohort study. ANIMALS 1,930 dogs gonadectomized between 1998 and 2001 at ≤ 6 months of age (n = 782), > 6 months to ≤ 1 year of age (861), or > 1 to ≤ 5 years of age (287) and 1,669 sexually intact dogs. PROCEDURES Dogs were followed-up through medical records for ≥ 10 years or until a diagnosis of overweight (defined as overweight, obese, or having a body condition score ≥ 4/5) was recorded. Information extracted included age at study entry, sex, breed, breed-size category, hospital visit frequency, and diagnosis (yes or no) of overweight or diseases that might affect body condition. Relative risk of a diagnosis of overweight was assessed among age groups of gonadectomized dogs and between gonadectomized and sexually intact dogs. RESULTS No difference was detected among dogs grouped according to age at gonadectomy with respect to the risk of being overweight. This risk was significantly greater in gonadectomized dogs than in sexually intact dogs, but only during the first 2 years after gonadectomy. Sexually intact male dogs were approximately 40% less likely to have this diagnosis (hazard ratio, 0.61; 95% confidence interval, 0.52 to 0.72) than were sexually intact female dogs; no difference in risk between the sexes was evident for gonadectomized dogs. CONCLUSIONS AND CLINICAL RELEVANCE Gonadectomized dogs had a greater risk of being overweight than did sexually intact dogs, but this risk was not influenced by age at gonadectomy. Opportunities exist for veterinarians to provide counseling during the first years after gonadectomy to help dogs maintain a healthy weight.

Factors associated with anesthetic-related death in dogs and cats in primary care veterinary hospitals

OBJECTIVE To identify risk factors for anesthetic-related death in pet dogs and cats. DESIGN Matched case-control study. ANIMALS 237 dogs and 181 cats. PROCEDURES Electronic medical records from 822 hospitals were examined to identify dogs and cats that underwent general anesthesia (including sedation) or sedation alone and had death attributable to the anesthetic episode ≤ 7 days later (case animals; 115 dogs and 89 cats) or survived > 7 days afterward (control animals [matched by species and hospital]; 122 dogs and 92 cats). Information on patient characteristics and data related to the anesthesia session were extracted. Conditional multivariable logistic regression was performed to identify factors associated with anesthetic-related death for each species. RESULTS The anesthetic-related death rate was higher for cats (11/10,000 anesthetic episodes [0.11%]) than for dogs (5/10,000 anesthetic episodes [0.05%]). Increasing age was associated with increased odds of death for both species, as was undergoing nonelective (vs elective) procedures. Odds of death for dogs were significantly greater when preanesthetic physical examination results were not recorded (vs recorded) or when preanesthetic Hct was outside (vs within) the reference range. Odds of death for cats were greater when intra-anesthesia records for oxygen saturation as measured by pulse oximetry were absent. Underweight dogs had almost 15 times the odds of death as nonunderweight dogs; for cats, odds of death increased with increasing body weight (but not with overweight body condition). CONCLUSIONS AND CLINICAL RELEVANCE Several factors were associated with anesthetic-related death in cats and dogs. This information may be useful for development of strategies to reduce anesthetic-related risks when possible and for education of pet owners about anesthetic risks.

Survival analysis to evaluate associations between periodontal disease and the risk of development of chronic azotemic kidney disease in cats evaluated at primary care veterinary hospitals

OBJECTIVE To examine potential associations between periodontal disease (PD) and the risk of development of chronic azotemic kidney disease (CKD) among cats and determine whether the risk of CKD increases with severity of PD. DESIGN Retrospective cohort study. ANIMALS 169, 242 cats. PROCEDURES Cats were evaluated ≥ 3 times at any of 829 hospitals from January 1, 2002, through June 30, 2013. Cats with an initial diagnosis of PD of any stage (n = 56,414) were frequency matched with cats that had no history or evidence of PD (112,828) by age and year of study entry. Data on signalment, PD, and other conditions potentially related to CKD were extracted from electronic medical records. Cox proportional hazards modeling was used to estimate the association of PD with CKD after controlling for covariates. RESULTS PD was associated with increased risk of CKD; risk was highest for cats with stage 3 or 4 PD. Risk of CKD increased with age. Purebred cats had greater risk of CKD than mixed-breed cats. General anesthesia within the year before study exit and diagnosis of cystitis at any point prior to study exit (including prior to study entry) were each associated with increased CKD risk. Diagnosis of diabetes mellitus or hepatic lipidosis at any point prior to study exit was associated with decreased CKD risk. CONCLUSIONS AND CLINICAL RELEVANCE The findings supported the benefit of maintaining good oral health and can be useful to veterinarians for educating owners on the importance of preventing PD in cats.

A moderate fat, low-energy dry expanded diet reduces gain in body condition score when fed as part of a post neutering weight-control regimen in growing pet cats*

Neutering of cats has been associated with significant weight gain in the weeks following surgery. The present study aimed to evaluate the effectiveness of a moderate fat, low-energy dry expanded diet in reducing weight gain in growing pet cats when fed as part of a weight-control regimen over the 6 months post-neutering. Cats in participating primary care veterinary hospitals were enrolled at neutering and assigned to receive one of the two dietary treatments based on the hospital of origin. Owners of cats in the treatment group were instructed to feed the trial diet at maintenance (324·7 kJ/kg BW0·711 per d). Instructions for the control group were to feed the cats regular diet according to the manufacturers recommendations. Body weight and condition were evaluated by veterinarians at enrolment, 2-weeks, and 1–4 and 6 months after surgery. Body condition score (five-point scale) was compared between enrolment and each subsequent visit, controlling for enrolment age and sex. Percentage change in body weight was evaluated via multivariate mixed modelling to account for repeated measures. A total of 187 cats (eighty-seven females and 100 males) with a mean age of 5·2 (sd 0·8) months and mean weight of 2·8 (sd 0·6) kg from fifty-one hospitals completed the trial. The odds of being scored as overweight were 4·1 times as great for cats in the control v. treatment groups (95 % CI 2·1, 8·2). Percentage change in body weight differed significantly with enrolment age (P = 0·007) and approached significance between diet groups (P = 0·08). Cats fed the trial diet had a significantly reduced incidence of overweight in the 6 months following neutering.