A 2-year-old male castrated domestic shorthair cat was presented to his veterinarian for suspect urethral obstruction. On presentation, he was documented to have a BCS of 3 on a 5-point scale, weighing 4.85 kg. A full, hard bladder was palpated, and white, gritty material was noted at the tip of his penis. Pre-anesthetic bloodwork revealed few abnormalities (see Table 1). A catheter was passed with some resistance, allowing emptying of the bladder. Copious amounts of "sand" were present in the urine. Urine pH was 8.0, cocci bacteria and large quantities of struvite crystals were detected (Table 2). Due to the presence of struvite crystals in the urine and small uroliths visualized by ultrasound, a canned feline veterinary therapeutic diet formulated for dissolution and prevention of struvite uroliths was recommended (Table 3). Previously, the cat had been fed commercial plant-based diets (Table 3). The cat was discharged with amoxicillin-clavulanic acid (62.5 mg Q12h PO, 10 days), prazosin (0.5 mg Q12h PO, 15 days, then 0.5 mg Q24h, 15 days), buprenorphine (0.08 mg Q8h PO, 16 days, tapering to 0.04 mg Q24h as required), and robenacoxib (6 mg PO SID, 6 days). Alprazolam (0.5 mg Q12h, 14 days) was also prescribed for underlying anxiety. The cat re-presented twice over the following 5 weeks with acute difficulty urinating, vocalizing, straining, and urinating outside of the litter box. No abnormalities were detected on physical examinations and urinalyses revealed improvement in urine acidity with fewer struvite crystals. Against recommendations, the client discontinued the therapeutic food as it contained animal products, and the cat was returned to his previous commercial plant-based diet.
One month later, the cat was referred to the Ontario Veterinary College Health Sciences Centre Clinical Nutrition Service for consultation regarding plant-based dietary management for FLUTD. The owner was vegan and required that they feed the cat a plant-based diet in order to comply with their ethics. On presentation, the cat had a BCS of 5/9, weighing 5.0 kg. Nutritional evaluation revealed risk factors based on the WSAVA Nutritional Evaluation Checklist, including living in a multi-cat house, ongoing urinary signs, and being fed an unconventional diet. The cat's resting energy requirement (RER) was estimated using: (BW0.75*70 kcal) = 250 kcal. Given the cat's activity, current bodyweight and BCS, his daily energy intake was estimated to be RER*1.2 = 300 kcal. A recommendation was made for a commercial feline veterinary therapeutic diet formulated to manage signs of FLUTD (Table 3), which was declined by the client as it contained animal products. After discussing the challenges related to management with a plant-based diet, commercial plant-based diets were identified as alternative strategies. While detailed nutrient profiles are not typically available for many commercial plant-based diets available in Canada, nutrient analyses had been performed as part of a research project conducted by the authors. Diets meeting the AAFCO adult maintenance recommendations with the lowest concentration of struvite precursors were identified (Table 3). Based on energy density, food doses were recommended to combine kibble and canned food in a 50:50 ratio. The recommendation was made for the cat to be fed 35 g (143 kcal) kibble and 150 g (148 kcal) canned food, allowing for 10 kcal (3% of daily energy intake) to be given as treats or snacks. The client was advised on the energy and nutrient content of suitable treats and snacks. Recommendations were made to encourage water intake, feed small, frequent meals, and to supplement the diet with eicosapentaenoic acid and docosahexaenoic acid (EPA+DHA) at a dose equivalent to 0.5% of the diet on a dry matter basis. Recommendations to increase water intake included adding water to food, adding palatants to water, providing multiple water dishes in different locations, different materials (e.g., ceramic or metal), offering wide dishes to avoid whisker stimulation, and drinking fountains.
Three months later, the cat re-presented to his veterinarian for inappetence and weight loss. His bodyweight was recorded at 4.30 kg, though BCS was still documented as 3 on a 5-point scale. According to dietary anamnesis the cat would not eat the canned diet, nor accept soaked kibble or the DHA+EPA supplement recommended by the Clinical Nutrition Service, and he had continued to be fed the commercial plant-based diet he had been fed prior to the urethral obstruction (Table 3). Urine was collected by the client using non-absorbent litter (Table 2). A veterinary therapeutic dissolution diet was again discussed with the client as being the most evidence-based solution to mitigate risk of recurrent FLUTD signs, but the client declined this recommendation. Mirtazapine (2 mg Q24-48h as required) was prescribed to stimulate food intake. Though no dietary change was implemented, recheck examination 3 weeks later revealed a slight increase in body weight from 4.30 to 4.43 kg. Four months later, the cat re-presented for decreased urine output. At that time his body weight was 4.51 kg and his BCS was documented as 5 on a 9-point scale. Free-flow urine was examined again (Table 2), and a feline veterinary therapeutic dissolution diet was recommended, but again declined. The client elected to try to increase water intake and began preparing a home-cooked plant-based diet (Table 4).
Three months later, the cat was re-presented to the Clinical Nutrition service for management of inappetence. Despite the client's concerns about the cat's intake, on presentation the cat weighed 5.8 kg with a BCS of 6 on a 9-point scale, his heaviest recorded weight. Evaluation of the home-cooked plant-based diet using diet formulation software (Balance IT ) revealed the diet to be deficient in numerous nutrients, most notably meeting 0% of the cat's arachidonic acid requirement, while it provided iodine over 8 times the maximum recommended dose (Table 3). On a daily basis, the cat was fed: 1 tbsp homemade food, 2 tbsp of vegetables (pumpkin, green lentils, peas, squash, green beans, or corn), 3/4 cup of kibble B, 1/8 tsp enzyme supplement, 250 mg methionine, and 1/8 tsp psyllium. The diet recipe was reported to have been acquired from a friend and it was unknown where the dosing had been acquired for the supplementation of enzymes, methionine, or psyllium. Treats included commercial plant-based deli slices, non-dairy cheese, potato chips, coconut yogurt, non-dairy sour cream, and dried nori seaweed. The client was made aware that the cat was slightly overweight and that his estimated daily caloric intake was more than sufficient to maintain his current bodyweight. Concern for inappetence or inadequate intake was not necessary. As the cat would not eat a canned food or soaked kibble, it was suggested to combine the kibble with preferred plant-based treats and foods the cat would eat, while also increasing water intake. The client was advised not to feed more than 10% of the daily caloric allotment from foods other than the kibble. Additionally, the methionine dose was increased from 250 to 500 mg to acidify the urine.
One month later, the cat was eating the recommended food, but struvite crystalluria persisted and the owner was concerned about inability to increase water intake on the dry extruded diet. The cat was re-presented to the Clinical Nutrition Service, weighing 5.8 kg with a BCS of 6 on a 9-point scale. A homemade plant-based diet was designed using web-based formulation software1 (Tables 3, 4) to meet the AAFCO nutrient profile for adult maintenance with low concentrations of struvite precursors, and utilized ingredients intended to promote urine acidity. Acidification of the urine was predicted by calculation of the base excess of the diet. Base excess in the food was calculated using the equation: Base excess (mmol/kg DM) = 2[Ca]+2[Mg]+[Na]+[K]-2[P]-2[Met]-[Cl]. Plant-based fatty acid supplementation was recommended, with plant-based arachidonic acid and EPA+DHA. As the cat was slightly overweight, a conservative energy intake was recommended to just meet his RER of 250 kcal to prevent further weight gain. The next urinalysis performed revealed a stable USG and pH, though struvite crystals were absent. The client was encouraged to continue regular rechecks with their family veterinarian, and feedback from the client 9 months later revealed the cat was doing well, he continued to eat a combination of the homemade food and commercial plant-based kibble, his urine was consistently free of struvite crystals, pH maintained between 6.5-7.0, and the USG below 1.040. The owner reported no further concerns with inappetence, no changes in bodyweight, and the cat had suffered no further FLUTD episodes.