The association between taurine concentrations and dog characteristics, clinical variables, and diet in English cocker spaniels: The Canine taURinE (CURE) project

Abstract

Background: Occurrence of low blood taurine concentrations (B-TauC) and predisposing factors to taurine deficiency in English Cocker Spaniels (ECS) are incompletely understood.

Objectives: Investigate the occurrence of low B-TauC in a Swedish population of ECS and evaluate the association between B-TauC and dog characteristics, clinical variables, and diet composition.

Animals: One-hundred eighty privately owned ECS.

Methods: Dogs were prospectively recruited and underwent physical examination, blood analyses, and echocardiographic and ophthalmic examinations. Dogs with clinical signs of congestive heart failure (CHF) also underwent thoracic radiography. Taurine concentrations were analyzed in plasma (EDTA and heparin) and whole blood. Diets consumed by the dogs at the time of the examination were analyzed for dietary taurine- (D-TauC), cysteine- (D-CysC), and methionine concentrations (D-MetC).

Results: Fifty-three of 180 dogs (29%) had low B-TauC, of which 13 (25%) dogs had clinical and radiographic signs of CHF, increased echocardiographic left ventricular (LV) dimensions and volumes, and impaired LV systolic function. Five (9%) dogs with low B-TauC had retinal abnormalities. Dietary MetC, dietary animal protein source (red/white meat), and age were associated with B-TauC in the final multivariable regression model (P < .001, R² _adj = .39).

Conclusions and clinical importance: Low B-TauC suggests that taurine deficiency may play a role in the development of myocardial failure and CHF in ECS. Low D-MetC and diets with red meat as the animal protein source were associated with low B-TauC. Dogs with B-TauC below the normal reference range were older than dogs with normal concentrations.

Keywords: amino acids; diet‐associated DCM; dogs; heart disease; retinal degeneration; taurine deficiency.

FIGURE 1

Box and whiskers plots demonstrating EDTA‐plasma taurine concentrations (EDTA‐TauC) in dogs with normal taurine concentrations (nB‐TauC) n = 127, dogs with low taurine concentrations and normal echocardiograms (

FIGURE 2

(A) Fundoscopy of a dog with normal fundus. (B) Fundoscopy in a 5‐year‐old female English Cocker Spaniel with abnormal EDTA‐plasma taurine concentration (<7.99 nmol/mL) showing retinal lesions similar to those reported in taurine‐depleted cats, including an elliptical hyperreflective lesion in the area centralis and visual streak (encircled area). Lesions were bilaterally symmetrical. (C) Fundoscopy in an 8‐year‐old female English Cocker Spaniel with abnormal EDTA‐plasma taurine concentration (<7.99 nmol/mL) showing retinal lesions including tapetal hyperreflectivity and vessel attenuation in the periphery (*). Lesions were bilaterally symmetrical. The dog was severely visually impaired.

FIGURE 3

Staple diagram demonstrating the distribution of protein sources in the various diets consumed by the included dogs. Diets with several different red or white meat components in the same diet were categorized as “mix red” and “mix white”. Diets based on a mixture of red and white meat in the same diet, and diets based on soy, vegetables, and insects and were excluded in this analysis. Percentages indicate the proportion of the 173 dogs that consumed the different diets containing either red or white meat as protein source.

FIGURE 4

(A) Scatterplots demonstrating EDTA‐taurine concentrations by dietary methionine concentrations and regression line with shaded 95% confidence interval (CI) in 167 English Cocker Spaniels consuming dry diets. Red‐filled small dots represent dogs consuming diets based on red meat and black‐filled small dots represent dogs consuming diets based on white meat. Red and black circles represent dogs diagnosed with congestive heart failure and low taurine concentrations that had consumed diets based on red (red circles) and white (black circles) meat, respectively. Low dietary methionine concentrations were associated with low EDTA‐taurine concentrations (P < .001, R ² _adj = .23). D‐MetC: Dietary methionine concentrations, EDTA‐TauC: EDTA‐taurine concentrations. (B) Box and whiskers‐plot demonstrating B‐TauC in 173 dogs consuming diets based on protein sources categorized as red meat (lamb, beef, venison, and pork; n = 61) and protein sources categorized as white meat (fish, poultry; N = 112). Seven dogs consumed diets based on a mixture of red and white meat or diets based on soy, vegetables, and insects, and these dogs were excluded in this analysis. Taurine concentrations were significantly lower in dogs fed a diet based on red meat then dogs fed a diet based on white meat (P < .001, R ² _adj = .21). The horizontal line corresponds to the normal lower reference value for EDTA‐plasma communicated by IDEXX laboratories, Germany. TauC: Taurine concentrations. (C) EDTA‐taurine concentrations by age and regression line with shaded 95% confidence interval (CI) in 180 ECS. Taurine concentrations decreased with increasing age (P < .02, R ² _adj = .02).