Hot Literature: Can GAGs alleviate clinical signs of idiopathic cystitis in cats?

A common condition in cats, lower urinary tract disease is often nonobstructive in nature. In fact, according to a 1997 study 45% to 70% of feline lower urinary tract disease is diagnosed as idiopathic cystitis. The clinical signs associated with idiopathic cystitis (dysuria; stanguria; hematuria; pollakiuria; and periuria, or inappropriate urination) are thought to be due to various anomalies in the bladder, central nervous system, and hypothalamic-pituitary-adrenocortical axis. Changing a cat’s environment, reducing stress, and increasing water consumption are some proposed ways to lessen the clinical signs of idiopathic cystitis.

One hypothesis regarding the cause of clinical signs of idiopathic cystitis involves the glycosaminoglycans (GAGs) lining the bladder. One such GAG is part of the normal bladder urothelium and is thought to protect the bladder from noxious or toxic substances and prevent bacterial and crystal adhesion. In people, the amount of GAGs in the urine decreases in cases of idiopathic cystitis, and oral supplementation has had some success.

Study design

To evaluate the possible benefits of orally administered GAGs in cats with idiopathic cystitis, researchers in Thailand recruited 10 clinically healthy client-owned cats and 19 with signs associated with idiopathic cystitis. The cats with idiopathic cystitis all had evidence of an irregular mucosal surface of the urinary bladder wall observed on ultrasonographic examination and no evidence of uroliths in the bladder on double-contrast cystography. Urinalyses were performed, and plasma and urine GAG concentrations and urine creatinine concentrations were measured repeatedly throughout the 28-day study and again at a follow-up visit on day 58. The healthy cats were tested initially for comparison.

The cats with idiopathic cystitis were divided into two treatment groups. One group received 250 mg N-acetyl-d-glucosamine (NAG), an exogenous GAG, orally once a day for 28 days, and the other group was given a placebo (cellulose capsule). None of the cats had any history or evidence of urolithiasis, urinary tract infection, bladder neoplasia, congenital deformity of the urinary tract, or any other serious medical condition. The owners were all interviewed for information regarding their cats’ diet, water intake, lifestyle, and environment. Most of the cats lived in multicat households and were fed dry food—both risk factors for developing idiopathic cystitis. At the beginning of the study, owners were counseled on the care of their cats and on changing their cats’ environment.

Study results

Owners of the treated cats reported fewer signs of pain on urination at the end of the four-week study, and, from a laboratory standpoint, there was a significant decrease in the finding of hematuria after the NAG treatments, which recurred when NAG administration was discontinued. The initial urine GAG-to-creatinine ratios for the cats with idiopathic cystitis were significantly lower than those of the clinically normal cats, and on day 21, cats in the NAG treatment group had mean GAG plasma concentrations that were substantially higher than those in the placebo-treated group. Furthermore, the increased plasma GAG concentrations of the cats treated with NAG were much higher than before treatment.

These results suggest that it may take up to 21 days in cats before an increase in plasma GAG is observed. Furthermore, no adverse effects were seen with the administration of NAG in any of the cats. As the authors of the study note, further research is needed to evaluate the long-term influence of oral NAG administration on clinical signs and the urinary bladder epithelium before a conclusion can be made on the clinical significance of this therapy.

Panchaphanpong, J, Asawakarn T, Pusoonthornthum R. Effects of oral administration of N-acetyl-d-glucosamine on plasma and urine concentrations of glycosaminoglycans in cats with idiopathic cystitis. Am J Vet Res 2011;72(6):843-850.

Link to abstract: http://avmajournals.avma.org/doi/abs/10.2460/ajvr.72.6.843