Investigating fat metabolism disorders in South African Mini Schnauzers

by Dr Anthony Zambelli, Sr Jodi Venter, Dr Kenneth Joubert

Mini Schnauzers are the seventh most common breed in South Africa according to the Kennel Union of Southern Africa (KUSA) registration for the last few years. This popular, spirited and alert little breed is generally quite robust, but we do know from overseas studies that they are prone to an accumulation of triglycerides (TG), a type of fat distinct from cholesterol.

It is suspected (but not unequivocally proven) that this is due to a genetic liver enzyme defect that may affect 33% of dogs (USA data). No one knew the best or most effective management for this condition, which can lead to more serious clinical diseases like diabetes, pancreatitis, arterial clots and kidney issues (proteinuria leading to kidney failure).

Series of studies

In 2017, we conducted a very large study of the prevalence and management of this condition. We recruited 176 Miniature Schnauzers from KwaZulu-Natal and Johannesburg and drew blood samples (it’s important that dogs are starved for 12 hours before testing). Dogs with raised TG were randomised into one of two groups – a feeding trial with a low-fat diet (ACANA Light and Fit) or a TG-lowering drug (bezafibrate).

After four weeks, dogs were retested, and swapped to the opposite treatment – a ‘crossover’ trial that doubles up patient numbers, leading to better statistical robustness. After the trial, we also did a smaller nine-patient trial of known positive dogs with a related diet, ORIJEN Fit and Trim – some of these dogs were on ‘raw’ home-formulated diets, and had massively raised TG.

The results

The results and conclusions from these tests are as follows:

  1. Twenty-five per cent of Miniature Schnauzers in South Africa had raised TG and were therefore at risk for developing the life-threatening metabolic conditions at some point in the future.
  2. Even dogs as young as 12 months of age came back positive. Therefore, all Miniature Schnauzers should be tested annually from 12 months of age. Prevalence of positives increases as dogs get older. So, dogs who are negative now may become positive in time, or positive dogs who are well controlled may become uncontrolled later, without showing any signs of the change until disaster strikes. It is fundamental to continue to check your dog for the rest of his life.
  3. Food was as effective in lowering TG in almost all dogs, as bezafibrate was. Dietary management has the advantage of no side effects and easy compliance. Normal TG is less than 1.13, while severely elevated levels are considered to be over 4.00.
  4. The mean TG in the food group, which consisted of 44 dogs, was 2.68; by the end of the feeding trial, 73% (32 dogs) had completed the food trial with a final TG of 1.08, a mean drop of -1.80 units. Forty-eight per cent of dogs normalised their TG on the diet, although 91% had a final TG <2 mmol/L (mild hypertriglyceridaemia).

The mean TG in the bezafibrate group, also 44 dogs, was 2.45, equivalent to the food group; by the end of the trial, 61% (27 dogs) had completed the food trial with a final TG of 0.86, a mean drop of -1.65. This was slightly less, but with greater variation, so some dogs dropped a lot more than others. Sixty-one per cent of dogs normalised their TG on the diet, although 100% had a final TG <2 (mild hypertriglyceridaemia).

  • The diet resulted in a greater drop in TG level, although more dogs normalised on bezafibrate. There were more dropouts on the trial with bezafibrate, primarily due to gastrointestinal upset or renal issues. Some dogs may be so severely affected that both dietary management and bezafibrate are required. However, bezafibrate has some contraindications, such as pre-existing renal disease.
  • High lipids, high body mass (overweight) and being older are risk factors for high TG.

Synopsis

In summary, we were able to document a common, important disease in a popular breed; develop simple guidelines for diagnosis, management and monitoring; and document for the first time the true efficacy of a specific diet for the management of this important condition.

Acknowledgements: IDEXX Laboratories (SA), Packleader (SA), staff of Inanda Veterinary Specialist Hospital (KZN) and Fourways Veterinary Hospital (JHB)

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