TYPES OF CANINE RENAL DISEASE IDENTIFIED IN THE BULLMASTIFF

Cystinuria

Cystinuria is an inherited disease characterized by an inability to reabsorb the amino acid cystine in the kidney tubules, resulting in an excess of cystine in the urine. Cystine is insoluble in neutral or acidic urine, so the formation of cystine crystals or, possibly, cystine uroliths (stones or calculi) in the kidneys, bladder, or urethra can result.

Because of the physiology of the male, irritation and blockage by calculi is much more common than in the female. ( Oifer's note*... this would imply that females can be affected and have similar symptoms as in the male, although less frequent) Afflicted animals may present with recurrent urinary tract inflammations; they may experience difficulty in urination or pass blood-tinged urine. Males may become completely blocked and can face kidney failure, bladder rupture and death, while cystinuric bitches may remain asymptomatic.

Use of a specific urinary screening method, the nitroprusside spot test, will give a reliable diagnosis; examination of the urine for cystine crystals is not a reliable indicator since these crystals are not always present in the urine. Surgical removal of stones may be indicated. Special diets and medications may be helpful, but their efficacy has not yet been documented. There are two common drugs of choice that bind cystine and prevent crystal formation and, in some cases, they have been found to dissolve small stones, but not all dogs respond well to this treatment.

In Newfoundlands, cystinuria is inherited as an autosomal recessive trait. In simple terms, this means that affected dogs of both sexes have two mutant (diseased) genes. Their parents are either "carriers" (asymptomatic but carrying both a normal and a mutant gene) or are also affected (with two mutant genes). Due to the efforts of Newfoundland fanciers and Dr. Paula Henthorn at the University of Pennsylvania School of Veterinary Medicine, there is now a DNA test available which can determine the genetic status of individual Newfoundlands before breeding.

The disease has also been identified in Mastiffs and Bullmastiffs, though there is not yet confirmation of the autosomal recessives mode of inheritance in these breeds. At present, there exists no specific screening process for Bullmastiffs. 

Methylsulfonylmethane (MSM) -- also known as methyl sulfone or dimethylsulfone (DMSO₂) -- is an odorless breakdown product of dimethyl sulfoxide

In living organisms, sulfur is found mainly in organic molecules. Humans obtain it by absorbing the sulfur-containing amino acids methionine, cysteine, and cystine [8]. Thus it is automatically obtained by consuming adequate amounts of protein foods (meat, fish, poultry, eggs, milk, cheese, nuts, and legumes) and requires no separate consideration.

Limited amounts are present in inorganic sulfates, sulfides, and thiamin; and sulfur is also a part of biotin and pantothenic acid. Although sulfur is considered to be an essential mineral, no dietary requirement for inorganic sulfur has been found and no Recommended Dietary Allowance or Estimated Safe and Adequate Daily Dietary Intake has been established for it. In fact, the 10th edition of Recommended Dietary Allowances does not discuss it.

The claim that MSM is an important source of dietary sulfur is unsupported by published research. One study that involved feeding MSM to guinea pigs found that the sulfur from MSM was absorbed rapidly into the blood stream and was incorporated into methionine and cysteine of serum proteins. However, most of the sulfur appeared in the urine; less than 1% was incorporated into serum proteins. Increasing the dosage of MSM 100-fold increased the incorporation into serum proteins only 3-fold, indicating that the capacity to use MSM in this pathway is limited [12]. Thus, while MSM is naturally present in small amounts in a variety of foods, its contribution to sulfur metabolism in humans is likely to be negligible.