Journal of Feline Medicine and Surgery

The case records of 106 cats with idiopathic cardiomyopathy that presented to the Feline Centre of the University of Bristol between September 1994 and September 2001 were reviewed retrospectively. Hypertrophic cardiomyopathy (HCM) was the most common form seen (57.5%), followed by restrictive cardiomyopathy (RCM) (20.7%), dilated cardiomyopathy (DCM) (10.4%) and unclassified cardiomyopathy (UCM) (10.4%). One cat showed echocardiographic changes compatible with a moderator band cardiomyopathy (MBCM). Most affected cats were domestic short hairs (DSH) (57.5%). The mean (±SD, range) age of cats with cardiomyopathy at presentation was 6.8 (4.3, 0.5–16) years, with an equal distribution of males and females. Clinical findings, electrocardiographic changes and radiographic abnormalities were also reviewed. The median survival time for 73 cats for which follow-up data was available was 300 days. A greater survival time was observed for cats with UCM (925 days) when compared with those with HCM (492 days), RCM (132 days) or DCM (11 days).

Spontaneous recovery from Microsporum canis infections in cats is thought to be dependent on the development of a competent immune response. The purpose of this study was to determine the prevalence of positive delayed type hypersensitivity reactions in cats with and without dermatophytosis. Four groups of cats were intradermally skin tested with M canis extract and test sites were evaluated both subjectively and objectively at 0, 24 and 48 h after injection. Delayed intradermal testing (IDT) reactions were absent in cats not exposed to dermatophytosis (n=20); infected–recovered cats (n=38 culture negative lesion negative and n=43 lesion negative but culture positive) had significantly larger IDT reactions than unexposed cats and cats that were still actively infected (n=18). Based on the results of this study, IDT with M canis extract can be used to assess the cellular immune response of cats with dermatophytosis.

The effect of short chain fatty acids (SCFA) on feline colonic smooth muscle contraction was evaluated in vitro. Colonic tissue was obtained from seven healthy male and female adult cats and seven healthy male and female kittens. Longitudinal and circular colonic smooth muscle strips from proximal and distal colon were incubated with SCFA (acetate, butyrate and propionate; 1–100 mM). SCFA-induced contractions were compared to responses obtained using maximal concentrations (10⁻⁴ M) of acetylcholine (ACh). The calcium dependence of the SCFA response was investigated by incubating with nifedipine (1 μM) or verapamil (1 μM).

Acetate, butyrate and propionate elicited isometric stress responses (0.25–1.98×10⁴ N/m²) in longitudinal, but not circular, smooth muscle from both the proximal and distal colon of adult cats. Maximal responses were attained at 50 and 100 mM SCFA. Maximal butyrate and propionate responses were 29 and 19% of the maximal ACh response (10⁻⁴ M), respectively. Acetate was least effective in stimulating contractile responses. Nifedipine and verapamil abolished all responses. Contractile responses in kittens were similar to those observed in adult cats, but were smaller in amplitude.

Results of these studies have shown that SCFA stimulate longitudinal colonic smooth muscle contractions in kittens and adult cats in vitro. These SCFA-induced contractions involve activation of calcium influx. These in vitro findings may account for some of the effects of dietary fiber on feline colonic motility in vivo.

Glomerular filtration rate (GFR) was determined in 53 cats using an inulin single-injection method. Thirty healthy young adult cats were used to establish normal values. The procedure was also used in 23 cats that were either older than 10 years or had borderline serum creatinine levels. The total clearance was calculated from the decay of the serum inulin concentration after injection of 3000 mg/m²body surface area using a two-compartment model. Concomitant inulin and iohexol clearance in nine cats showed excellent correlation between the two methods. Calculated normal values for GFR in 30 healthy cats were 35.9–58.5 (median 46.0) ml/min/m²or 2.07–3.69 (median 2.72) ml/min/kg. A few cats with normal creatinine or blood urea nitrogen levels were detected as having reduced GFR and therefore being in a state of early renal dysfunction. The study indicates that single-injection inulin clearance is a valuable tool for routine GFR measurement in cats. An ‘inulin excretion test’ using only one blood sample 3 h after the administration of 3000 mg/m²body surface area could prove an attractive alternative for the assessment of renal function in daily practice.

The purpose of this study was to determine the effect of an α-glucosidase inhibitor (acarbose), combined with a low-carbohydrate diet on the treatment of naturally occurring diabetes mellitus in cats. Eighteen client-owned cats with naturally occurring diabetes mellitus were entered into the study. Dual-energy X-ray absorptiometry (DEXA) was performed prior to and 4 months after feeding the diet to determine total body composition, including lean body mass (LBM) and percent body fat. Each cat was fed a commercially available low-carbohydrate canned feline diet and received 12.5 mg/cat acarbose orally every 12 h with meals. All cats received subcutaneous insulin therapy except one cat in the study group that received glipizide (5 mg BID PO). Monthly serum glucose and fructosamine concentrations were obtained, and were used to adjust insulin doses based on individual cat's requirements. Patients were later classified as responders (insulin was discontinued, n=11) and non-responders (continued to require insulin or glipizide, n=7). Responders were initially obese (<28% body fat) and non-responders had significantly less body fat than responders (<28% body fat). Serum fructosamine and glucose concentrations decreased significantly in both responder and non-responder groups over the course of 4 months of therapy. Better results were observed in responder cats, for which exogenousinsulin therapy was discontinued, glycemic parameters improved, and body fat decreased. In non-responders, median insulin requirements decreased and glycemic parameters improved significantly, despite continued insulin dependence. The use a low-carbohydrate diet with acarbose was an effective means of decreasing exogenous insulin dependence and improving glycemiccontrol in a series of client-owned cats with naturally occurring diabetes mellitus.

In a controlled study, the effects of amitriptyline compared with that of a placebo in cats suffering from idiopathic Feline Lower Urinary Tract Disease (FLUTD) have been investigated. Thirty-six animals were selected by veterinary practitioners and treated with a placebo or 10 mg amitriptyline once daily. All animals received concomitant antibiotic treatment. A total of 24 cats were included in the final assessment of the results. The severity of symptoms before and after treatment were compared between groups and showed no significant difference. Results indicated that the 7-day course of 10 mg amitriptyline was not effective in the treatment of idiopathic FLUTD. Thus, it is considered not to be beneficial as a short-term therapy where the therapeutic results depend on peripheral effects of the drug. Long-term effects may be expected 4 or more weeks after the start of therapy and need to be further investigated.

A seven-year-old castrated British shorthair cross cat was presented for coughing of five-weeks duration. Thoracic radiographs and an unguided bronchoalveolar lavage showed changes consistent with inflammatory airway disease. In addition, a soft tissue density was evident in the thoracic films between the heart and the diaphragm. Exploratory thoracotomy demonstrated a diaphragmatic hernia, probably congenital in origin, with incarceration of a portion of the hepatic parenchyma. The herniated portion of liver was resected surgically and the defect in the diaphragm closed. The cat was given a 10-day course of doxycycline post-operatively and the cough did not recur subsequently. In retrospect, the hernia was potentially an incidental problem, the cat's coughing being attributable to inflammatory airway disease.