Influence of age and body size on gastrointestinal transit time of radiopaque markers in healthy dogs

OBJECTIVE: To compare gastric emptying time, small-intestinal transit time (SITT), and orocecal transit time (OCTT) of radiopaque markers in dogs varying in age and body size and to determine whether fecal variables (ie, consistency and moisture content) are related to gastrointestinal tract transit times in dogs. ANIMALS: 24 eight-week-old female puppies, including 6 Miniature Poodles, 6 Standard Schnauzers, 6 Giant Schnauzers, and 6 Great Danes. PROCEDURE: Gastrointestinal tract transit time experiments were performed at 12, 22, 36, and 60 weeks of age. Dogs were fed 30 small radiopaque markers mixed with a meal. Abdominal radiographs were taken. The time at which 50% of the markers had left the stomach (T50) and the time at which the first marker reached the colon were calculated. Fecal moisture content and scoring on the basis of fecal consistency were recorded during the same periods. RESULTS: Puppies had a shorter mean T50 than adults, and mean OCTT decreased significantly only during growth of large-breed dogs. However mean fecal moisture content significantly increased with age, except in Giant Schnauzers. No effect of body size on T50 was found regardless of age, and no difference was observed between OCTT of small- and large-breed adult dogs. The effect of age on the mean SITT was not significant for any breed. However, a strong positive correlation was recorded between body size and fecal moisture content (r2 = 0.77) or fecal scores (r2 = 0.69) in adult dogs. CONCLUSIONS AND CLINICAL RELEVANCE: Age affects T50 in small- and large-breed dogs and OCTT in large-breed dogs. However, body size does not affect T50 or OCTT. A relationship does not exist between gastrointestinal tract transit time and fecal variables in healthy dogs.     

Influence of age and body size on orocecal transit time as assessed by use of the sulfasalazine method in healthy dogs

OBJECTIVE: To compare orocecal transit time (OCTT) as assessed by use of the sulfapyridine appearance time in plasma after oral administration of sulfasalazine in dogs of varying age and body size and determine whether OCTT correlates with fecal quality. ANIMALS: 6 Miniature Poodles (MP), 6 Standard Schnauzers (SS), 6 Giant Schnauzers (GS), and 6 Great Danes (GD). PROCEDURE: Determinations of OCTT were made at 12, 22, 36, and 60 weeks of age. Dogs were fed sulfasalazine mixed with a meal. Blood samples were then collected for 6 hours. The OCTT was the time from ingestion of the meal to detection of sulfapyridine in plasma. Fecal moisture content and consistency were recorded during the same periods. RESULTS: Mean OCTT decreased during growth of GS and GD dogs. No correlation was found between OCTT and fecal variables during growth in the 4 breeds. Effect of body size was observed at 12 and 22 weeks of age, with a longer OCTT in GS and GD than in MP and SS dogs. Similar OCTTs were observed at 36 and 60 weeks of age in all breeds, although GS and GD dogs had poorer fecal quality during those periods. CONCLUSIONS AND CLINICAL RELEVANCE: An effect of age on OCTT was observed only in large-breed dogs, with longer transit times in puppies (12 weeks old) than in adults (60 weeks old). Mean OCTT is not correlated with body size in adult dogs. No relationship was detected between OCTT and fecal variables in healthy dogs.     

Colonic permeability is higher in Great Danes compared with smaller breed-dogs

Fed the same dry diet, large dogs show poorer fecal quality than small ones. A high colonic permeability could explain a low water and electrolyte net balance leading to high fecal water content. This experiment was conducted to evaluate colonic permeability in dogs varying in body size and to determine whether colonic permeability is related to fecal sodium concentration and fecal quality. Four breeds of dogs were used: six Miniature Poodles (MP), six Standard Schnauzers (SS), six Giant Schnauzers (GS) and six Great Danes (GD). Colonic permeability was evaluated using the ratio of urinary lactulose to sucralose (L:S) after oral administration. Fecal sodium concentration was measured by flame photometry. The urinary L:S ratio was significantly lower in GD, indicating a higher colonic permeability, than in the three other breeds (0.35 ± 0.12 for GD and 0.51 ± 0.05 for MP). GD also presented the higher fecal sodium concentrations and the poorest fecal quality. The higher fecal sodium concentration observed in GD could be explained by the higher colonic permeability and both these variables could be important explanations for higher fecal moisture in large dogs.     

Influence of age and body size on intestinal permeability and absorption in healthy dogs

OBJECTIVE: To evaluate effects of age and body size of dogs on intestinal permeability (unmediated diffusion) as measured by the ratio of urinary lactulose to L-rhamnose (L:R) and absorption (carrier-mediated transport) as measured by the ratio of urinary D-xylose to 3-O-methyl-D-glucose (X:MG) and to determine whether these variables correlated with fecal quality. ANIMALS: 6 Miniature Poodles, 6 Standard Schnauzers, 6 Giant Schnauzers, and 6 Great Danes. PROCEDURE: A solution that contained lactulose and rhamnose or xylose and 3-O-methyl-D-glucose was administered orally to dogs that were 12, 22, 36, and 60 weeks old. Urine was collected 6 hours later, and urinary L:R and X:MG were calculated. Fecal moisture and scoring were recorded during the same periods. RESULTS: Age and breed did not affect intestinal absorption, and we did not detect a relationship between X:MG and fecal variables. In contrast, we detected significant effects of age and body size on intestinal permeability. Puppies (12 weeks old) and large dogs had higher intestinal permeability than adult (60 weeks old) and small dogs. The increased intestinal permeability in large dogs was associated with lower fecal quality as indicated by the significant positive correlations between L:R and fecal moisture (r, 0.61) and L:R and fecal scores (r, 0.86) in adult dogs. CONCLUSIONS AND CLINICAL RELEVANCE: These results indicate that age and body size should be considered when assessing intestinal permeability by use of the L:R urinary excretion test in dogs. High intestinal permeability could be a possible cause of poor fecal quality in large dogs.     

Effect of size on electrolyte apparent absorption rates and fermentative activity in dogs

The objectives of the study were to assess overall electrolyte absorption capacity as well as fermentative activity in dogs varying in body size in order to verify whether these parameters can explain the poor faecal quality in large dogs. Four breeds of dogs were used: six Miniature Poodles (MP), six Standard Schnauzers (SS), six Giant Schnauzers (GS) and six Great Danes (GD). Net absorption rates of electrolytes were assessed by calculating the apparent digestibility of sodium and potassium and measuring their content in stool. Fermentative activity was calculated by measuring faecal concentrations of lactic acid and short-chain fatty acids. The results showed higher faecal concentrations of fermentation products and electrolytes as well as poorer digestibility of electrolytes in Giant Schnauzers and Great Danes. Strong positive correlations were found between these different parameters and stool quality (scores and moisture). Lower overall electrolyte absorption and higher fermentative activity could thus be factors capable of explaining poorer faecal quality in these two large dog breeds.     

Influence of age and body size on the digestibility of a dry expanded diet in dogs

The objectives of the study were (i) to evaluate the effects of age and body size on the apparent digestibility of a dry expanded diet and (ii) to determine whether poor faecal quality could be related to lower nutrient utilization. Four breeds of dogs were used: six Miniature Poodles (MP), six Medium Schnauzers (MS), six Giant Schnauzers (GS) and six Great Danes (GD). Digestive trials were performed at 11, 21, 35 and 60 weeks of age. Faecal moisture and scoring were recorded at the same periods. Digestibility coefficients of all macronutrients increased significantly (p < 0.05) with age in all four breeds. Organic matter digestibility increased from 80.2 +/- 1.5 to 85.5 +/- 1.5% in MP; from 80.2 +/- 0.9 to 86.3 +/- 0.5% in MS; from 79.6 +/- 4.2 to 88.9 +/- 0.5% in GS and from 85.7 +/- 1.5 to 88.4 +/- 0.8% in GD. Crude protein digestibility increased from 74.5 +/- 4.0 to 81.5 +/- 1.9% in MP; from 74.3 +/- 3.9 to 82.6 +/- 0.9% in MS; from 71.8 +/- 6.0 to 85.9 +/- 0.9% in GS and from 80.8 +/- 4.6 to 84.8 +/- 1.3% in GD between 11 and 60 weeks of age, respectively. Mean faecal moisture also increased over the growth, except in GS. Nutrient digestibility was significantly higher in large dogs at all age periods. However, larger dogs showed lower faecal scores and increased faecal moisture. In conclusion, these results show (i) an effect of age and body size on nutrients digestibility and (ii) that the lower faecal quality observed in healthy large breed dogs does not appear related to lower nutrient utilization.     

Relationship between total transit time and faecal quality in adult dogs differing in body size

Fed the same diet, large and giant-breed dogs have higher faecal moisture and increased frequency of soft stools than small ones. This could be the result of physiological differences, such as a different gastrointestinal transit time. In this study, we have correlated mean total transit time (MTT) with body size and faecal consistency in dogs varying in body size. Fifty dogs from 13 different breeds were used, from a Dachshund to a Great Dane. The MTT was determined using coloured plastic beads [Cummings and Wiggins, Gut, Vol. 17 (1976), p. 219], and faecal consistency was scored daily during the study. We confirmed the strong correlation between height at the shoulder (body size) and faecal score (r = 0.76; p < 0.0001). The MTT increased with body size, from 22 h for a Miniature Poodle to 59 h for a Giant Schnauzer. We found significant positive correlations (p < 0.0001) between MTT and body size as well as faecal scores (r = 0.71 and 0.70 respectively). In the present study, we observed an effect of body size on MTT. In our 50 healthy dogs a longer MTT was related to a poorer faecal quality. Previous studies reported no relationship between body size and the upper gastrointestinal transit time in healthy dogs. So, we hypothesized that body size would mainly affect colonic transit time and that a longer colonic residence time would be related to a poorer faecal quality by promoting fermentation activity.     

Comparison of ultrasonographic characteristics of the thyroid gland in healthy small-, medium-, and large-breed dogs

OBJECTIVE: To determine ultrasonographic characteristics of the thyroid gland in healthy small-, medium-, and large-breed dogs and evaluate the relationships of thyroid gland size and volume with body weight and body surface area (BSA). ANIMALS: 72 dogs of small (6 Toy and 6 Miniature Poodles), medium (12 Beagles), and large breeds (12 Akitas and 36 Golden Retrievers). PROCEDURE: Each dog's thyroid gland was examined ultrasonographically with a 10- to 5-MHz multifrequency linear-array transducer. Size, shape, echogenicity, and homogeneity of thyroid lobes were evaluated on longitudinal and transverse images. Thyroid lobe volume was estimated by use of the equation for an ellipsoid (pi/6 [length x height x width]). RESULTS: Thyroid lobes appeared fusiform or elliptical on longitudinal images and triangular or round to oval on transverse images. In most dogs, thyroid lobes were hyperechoic or isoechoic, compared with surrounding musculature, and had a homogeneous echogenic pattern. Mean length, width, height, and volume of thyroid lobes were significantly greater in Akitas and Golden Retrievers, compared with findings in Beagles or Poodles; mean length, width, and height were significantly greater in Beagles, compared with findings in Poodles. Total thyroid gland volume correlated with body weight (r = 0.73) and BSA (r = 0.74). CONCLUSIONS AND CLINICAL RELEVANCE: Among the dog breeds examined ultrasonographically, thyroid lobe size and volume were more variable than shape, echogenicity, and homogeneity. The correlation of thyroid gland volume with BSA suggests that size of the dog, rather than breed, should be considered when assessing thyroid glands ultrasonographically.     

Evaluation of urine and serum metabolites in miniature schnauzers with calcium oxalate urolithiasis.

To evaluate underlying causes of calcium oxalate urolithiasis, 24-hour excretion of urine metabolites was measured in 6 Miniature Schnauzers that formed calcium oxalate (CaOx) uroliths during periods when they were fed a standard diet and during periods when food was withheld. Serum concentrations of parathyroid hormone and 1,25-dihydroxyvitamin D also were evaluated. Serum calcium concentrations were normal in all 6 affected Miniature Schnauzers; however, during diet consumption, mean 24-hour urinary excretion of calcium was significantly (P = 0.025) higher than calcium excretion when food was withheld. In 1 dog, urinary calcium excretion was lower during the period of food consumption, compared with the period when food was withheld. Compared with clinically normal Beagles, Miniature Schnauzers that formed CaOx uroliths excreted significantly greater quantities of calcium when food was consumed (P = 0.0004) and when food was withheld (P = 0.001). Miniature Schnauzers that formed CaOx uroliths excreted significantly less oxalate than clinically normal Beagles during fed (P = 0.028) and nonfed (P = 0.004) conditions. Affected Miniature Schnauzers also excreted abnormally high quantities of uric acid. Excretion of citrate was not different between Miniature Schnauzers with CaOx urolithiasis and clinically normal Beagles. In 5 of 6 Miniature Schnauzers with CaOx urolithiasis, concentrations of serum parathyroid hormone were similar to values from age- and gender-matched Miniature Schnauzers without uroliths. The concentration of serum parathyroid hormone in 1 dog was greater than 4 times the mean concentration of clinically normal Miniature Schnauzers. Mean serum concentrations of 1,25-dihydroxyvitamin D in Miniature Schnauzers with calcium oxalate urolithiasis were similar to concentrations of clinically normal Miniature Schnauzers.     

Prevalence of calcium oxalate uroliths in miniature schnauzers.

Epidemiologic data were evaluated from all dogs admitted to the University of Minnesota, Veterinary Teaching Hospital (UMVTH) between June 1981 and November 1989. Of 69,890 admissions, 2,077 were Miniature Schnauzers. Uroliths were retrieved from 63 of the 2,077 Miniature Schnauzers admitted. In 20 of the 63 urolith episodes, calcium oxalate was the predominant mineral identified. By comparison, calcium oxalate uroliths were identified in only 56 of the remaining 67,813 non-Miniature Schnauzer canine admissions. The odds that uroliths from Miniature Schnauzers were composed of calcium oxalate was 11.8 times greater than for other canine breeds evaluated at the UMVTH (95% confidence interval = 6.8 to 20.1). Data also were evaluated from files of uroliths retrieved from dogs and submitted to the Minnesota Urolith Center for quantitative mineral analysis, between June 1981 and November 1989. Of 3,930 uroliths analyzed, 615 (15.6%) uroliths were obtained from Miniature Schnauzers. of the 615 uroliths, 175 (28.4%) were calcium oxalate. By comparison, only 550 (16.6%) of the remaining 3,315 from dogs of breeds other than Miniature Schnauzers were calcium oxalate. The odds that uroliths submitted for analysis were composed of calcium oxalate was 2 times greater for Miniature Schnauzers than for dogs of other breeds (95% confidence interval = 1.6 to 2.4). Calcium oxalate uroliths were retrieved more frequently in males than females. The risk for males developing calcium oxalate uroliths was greater than 3 times the risk for females in both groups of data evaluated. The mean age of all Miniature Schnauzers admitted to the UMVTH with calcium oxalate uroliths was 9 years. Calcium oxalate uroliths were not detected in Miniature Schnauzers younger than 1.7 years.     

Serum triglyceride concentrations in Miniature Schnauzers with and without a history of probable pancreatitis

Background: The association between hypertriglyceridemia and pancreatitis remains obscure in dogs. A possible role of hypertriglyceridemia as a cause of pancreatitis in Miniature Schnauzers has been suspected. Hypothesis/Objectives: To compare serum triglyceride concentrations between Miniature Schnauzers with and without a recent history of pancreatitis. Animals: Seventeen Miniature Schnauzers with a history of pancreatitis (group 1) and 34 age‐matched Miniature Schnauzers without a history of pancreatitis (group 2) were prospectively enrolled. Methods: Prospective case‐control study. Two samples were collected from each of the 17 Miniature Schnauzers with pancreatitis: 1 during pancreatitis and 1 after clinical and biochemical resolution of pancreatitis. Serum triglyceride and cholesterol concentrations were compared between group 1 (after resolution of pancreatitis) and group 2. Results: Miniature Schnauzers in group 1 were significantly more likely to have hypertriglyceridemia (>108 mg/dL) (71%) after resolution of pancreatitis than Miniature Schnauzers in group 2 (33%; odds ratio = 5.02; 95% confidence interval = 1.4–17.8; P= .0163). Serum triglyceride concentrations were significantly higher in dogs of group 1 (median: 605.0 mg/dL) after resolution of pancreatitis than in dogs of group 2 (median: 73.5 mg/dL; P= .002). Conclusions and Clinical Importance: Miniature Schnauzers with a history of pancreatitis were 5 times more likely to have hypertriglyceridemia than controls. Hypertriglyceridemia might be associated with the development of pancreatitis in some dogs of this breed. Additional studies are needed to further clarify the role of hypertriglyceridemia in the development of pancreatitis in Miniature Schnauzers as well as other dog breeds.     

Breed distribution of dogs with diabetes mellitus admitted to a tertiary care facility

OBJECTIVE: To determine which dog breeds are at low and high risk for developing diabetes mellitus (DM). DESIGN: Cohort study. ANIMALS: Hospital population of 221 dogs with DM and 42,882 dogs without DM during 5.5 years. PROCEDURE: 165 breeds (including a mixed-breed category) were represented in the hospital population. Breed-specific expected numbers of dogs with DM were calculated by multiplying the proportion of all dogs admitted to the hospital that were determined to have DM during the study period by the breed-specific totals during the study period. Breeds or breed groups evaluated in the analysis (n = 20) were restricted to those that had a combined observed and expected count > 5 to document breeds at low and high risk for developing DM. Proportionate changes in the risk of developing DM by breed were calculated and presented using exact odds ratios, 95% confidence intervals, and P values. Mixed-breed dogs were chosen as the reference breed. RESULTS: Samoyeds, Miniature Schnauzers, Miniature Poodles, Pugs, and Toy Poodles were at high risk for developing DM. Dog breeds found to be at low risk for developing DM were German Shepherd Dog, Golden Retriever, and American Pit Bull Terrier. CONCLUSION AND CLINICAL RELEVANCE: The finding that certain dog breeds are at low or high risk for developing DM suggests that some genetic defects may predispose dogs to development of DM, whereas other genetic factors may protect dogs from development of DM.     

Serum liver enzyme activities in healthy Miniature Schnauzers with and without hypertriglyceridemia

OBJECTIVE: To determine whether hypertriglyceridemia in healthy Miniature Schnauzers is associated with high serum liver enzyme activities. DESIGN: Cross-sectional study. ANIMALS: 65 Miniature Schnauzers with serum triglyceride concentrations within the reference range (group 1), 20 Miniature Schnauzers with slightly high serum triglyceride concentrations (group 2), and 20 Miniature Schnauzers with moderately to severely high serum triglyceride concentrations (group 3). PROCEDURES: Questionnaires regarding each dog's medical history were completed, and serum alkaline phosphatase (ALP), alanine aminotransferase (ALT), aspartate aminotransferase (AST), and G-glutamyltransferase (GGT) activities were measured. RESULTS: Median serum ALP activity was significantly higher in group 3 than in group 1 or 2 dogs, but was not significantly higher in group 2 than in group 1 dogs. Median serum ALT activity was significantly higher in group 3 than in group 1 dogs, but was not significantly different between any of the other groups. Compared with group 1 dogs, group 2 and 3 dogs were significantly more likely to have high serum ALP activity (odds ratio, 26.2 and 192.6, respectively). Group 3 dogs also were significantly more likely to have high serum ALT activity (odds ratio, 8.0), serum AST activity (odds ratio, 3.7), and serum GGT activity (odds ratio, 11.3), compared with group 1 dogs. Group 3 dogs were significantly more likely (odds ratio, 31.0) to have > or = 2 high serum liver enzyme activities than were group 1 dogs. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that moderate to severe hypertriglyceridemia was associated with high serum liver enzyme activities in Miniature Schnauzers.     

Detection of a genetic mutation for myotonia congenita among Miniature Schnauzers and identification of a common carrier ancestor

OBJECTIVE: To develop a molecular genetic test to detect the mutant skeletal muscle chloride channel (CIC-1) allele that causes myotonia congenita in Miniature Schnauzers and to analyze the relationship of affected and carrier dogs. ANIMALS: 372 Miniature Schnauzers from the United States, Canada, Australia, and Europe that were tested between March 2000 and October 2001. PROCEDURE: The sequence surrounding the mutation in the CIC-1 allele was amplified by use of a unique pair of primers. Polymerase chain reaction (PCR) products were digested with the restriction enzyme Hpy CH4 III and separated on a 6% polyacrylamide gel. Pedigrees from all available carrier and affected dogs were analyzed, and a composite pedigree was established. RESULTS: Enzyme digestion of PCR products of the normal CIC-1 allele resulted in 3 fragments of 175, 135, and 30 bp, whereas PCR products of the mutant allele resulted in fragments of only 175 and 165 bp. Of the 372 Miniature Schnauzers, 292 (78.5%) were normal, 76 (20.4%) were carriers, and 4 (1.1%) were affected (myotonic) dogs. Frequency of the mutant allele was 0.113. Pedigree analysis revealed that a popular sire, documented to be a carrier, was a common ancestor of all carriers and affected dogs. CONCLUSIONS AND CLINICAL RELEVANCE: A PCR-based enzyme digestion DNA test was developed. The mutant allele for this disease is frequent in Miniature Schnauzers that are related to a common carrier ancestor. Breeding dogs should be tested by this specific DNA test to help limit the spread of this deleterious mutation.     

Cystine-containing urinary calculi in dogs: 102 cases (1981-1989).

One hundred and seven cystine-containing urinary calculi from 1 female and 101 male dogs were analyzed. Cystine-containing calculi accounted for 2% (107 of 5,375) of all canine urinary calculi submitted to the urinary stone analysis laboratory from July 1981 through December 1989. Male dogs that formed cystine calculi were compared with 3 other canine populations to determine whether certain breeds were apparently at increased or decreased risk for cystine calculus formation. In one or more of 3 population comparisons, significantly increased risk of cystine calculus formation was found in Mastiffs, Australian Cattle Dogs, English Bulldogs, Chihuahuas, Bullmastiffs, Newfoundlands, Dachshunds, Basenjis, Australian Shepherd Dogs, Scottish Deerhounds, Staffordshire Terriers, Miniature Pinschers, pitbull terriers, Welsh Corgis, Silky Terriers, and Bichon Frises. Significantly low risk of cystine calculus formation was found in German Shepherd Dogs, Poodles, Schnauzers, and mixed-breed dogs.     

Predisposition for primary hyperlipidemia in Miniature Schnauzers and Shetland sheepdogs as compared to other canine breeds

Miniature Schnauzers are the first canine breed, in the United States, reported to suffer from primary hyperlipidemia, but this has yet to be documented in other regions. Using over 900 canine plasma samples collected from over seven different veterinary clinics across Japan, the aim of this study was to compare plasma triglyceride (TG) and cholesterol concentrations between Miniature Schnauzers and other purebreeds in Japan. In addition, we investigated the influence of aging and sex on changes to hyperlipidemia incidence in purebred dogs. Our results indicated that both Miniature Schnauzers and Shetland sheepdogs in Japan exhibited remarkably high concentrations of plasma TG and total cholesterol, which are considered to be signs of hyperlipidemia, as compared to other purebred and mixed (Mongrel) canine breeds. Interestingly, the cause and conditions of primary hyperlipidemia in Miniature Schnauzers and Shetland sheepdogs might be different, with hypertriglyceridemia predominantly occurring with Miniature Schnauzers and hypercholesterolemia occurring in Shetland sheepdogs. However, with the influence of aging, the hyperlipidemia evolves into both hypercholesterolemia and hypertriglyceridemia in both groups indicating that the severity of hyperlipidemia positively correlates with aging. Gender differences were also observed with regards to severity. In fact, a higher severity was prevalent with female Miniature Schnauzers than their male counterparts whereas it was more balanced between genders for Shetland sheepdogs.     

Inherited retinal dysplasia and persistent hyperplastic primary vitreous in Miniature Schnauzer dogs

The objectives of this study were to define the clinical syndrome of retinal dysplasia and persistent primary vitreous in Miniature Schnauzer dogs and determine the etiology. We examined 106 Miniature Schnauzers using a biomicroscope and indirect ophthalmoscope. The anterior and posterior segments of affected dogs were photographed. Four enucleated eyes were examined using routine light microscopy and scanning electron microscopy. A pedigree was constructed and related dogs were test-bred to define the mode of inheritance of this syndrome. Congenital retinal dysplasia was confirmed in 24 of 106 related Miniature Schnauzer dogs. Physical and postmortem examinations revealed that congenital abnormalities were limited to the eyes. Biomicroscopic, indirect ophthalmoscopic, and neuro-ophthalmic examinations confirmed that some of these dogs were blind secondary to bilateral retinal dysplasia and detachment (nonattachment) (n = 13), and the remainder had generalized retinal dysplasia (n = 11). Fifteen of these dogs were also diagnosed with unilateral (n = 9) or bilateral (n = 6) persistent hyperplastic primary vitreous. Nutritional, infectious, or toxic etiologies were not evident on physical, postmortem, light microscopic, or transmitting and scanning electron microscopic examination of four affected Miniature Schnauzers. We examined the pedigree and determined that an autosomal recessive mode of inheritance was most likely. Three test-bred litters including those from affected parents, carrier and affected parents, and carrier parents confirmed this mode of inheritance. This study confirms that retinal dysplasia and persistent hyperplastic primary vitreous is a congenital abnormality that is inherited as an autosomal recessive condition in Miniature Schnauzers.     

Canine meibometry: establishing baseline values for meibomian gland secretions in dogs

Meibomian lipid secretions are essential in preventing tear evaporation. Disorders of the meibomian glands may therefore play an important role in the pathogenesis of some forms of keratoconjunctivitis sicca (KCS). Until now, meibomian lipid secretions have never been quantitatively evaluated in dogs. With the aim of establishing baseline values of canine meibomian lipid secretions, meibometry was conducted in 42 healthy dogs, 16 of which were Miniature Schnauzers. The mean meibomium level in 84 eyes of the 42 dogs was 179+/-60 Meibometer units. Age, gender and side did not affect the results. However, meibomium levels were significantly lower in the Miniature Schnauzers, a breed that is susceptible to KCS, compared to other breeds. This report demonstrates that meibometry is a simple and minimally invasive technique that may be readily used in conscious dogs to quantify meibomian gland secretions and explicate tear film dynamics in normal and dry canine eyes.     

Dental and craniofacial findings in eight miniature schnauzer dogs affected by myotonia congenita: preliminary results

Myotonia is a clinical sign characterized by the delay of skeletal muscle relaxation following the cessation of a voluntary activity or the termination of an electrical or mechanical stimulus. Recently, Miniature Schnauzers with myotonia congenita associated with defective chloride ion conductance across the skeletal muscle membrane were identified. Congenital myotonia in these dogs appears to follow an autosomal recessive mode of inheritance. Craniofacial and dental findings of eight Miniature Schnauzer dogs with myotonia congenita are described in the present paper. These findings include: delayed dental eruption of both deciduous and permanent dentition: persistent deciduous dentition; unerupted or partially erupted permanent teeth: crowding and rotation of premolar and or incisor teeth: missing teeth: increased interproximal space between the maxillary fourth premolar and first molar teeth: decreased interproximal space between the maxillary canine and lateral incisor teeth: inability to fully close the mouth due to malocclusion: distoclusion: and, decreased mandibular range of motion. A long narrow skull with a flattened zygomatic arch and greater mandibular body curvature were also consistent findings in the affected dogs. The small number of dogs studied prevents conclusive statements about the origin of these abnormalities, however it is interesting that only 1 of 45 unaffected Miniature Schnauzer dogs showed similar traits.     

Ultracentrifugal and Electrophoretic Characteristics of the Plasma Lipoproteins of Miniature Schnauzer Dogs With Idiopathic Hyperlipoproteinemia

To better characterize the idiopathic hyperlipoproteinemia of Miniature Schnauzer dogs, the plasma lipoproteins of 20 Miniature Schnauzers (MS) and 11 dogs of other breeds (DOB) were evaluated by ultracentrifugation, electrophoresis, and biochemical tests. Seventeen MS were healthy; 3 had diabetes mellitus. Plasma from 6 of 17 healthy and all 3 diabetic MS was visibly lipemic. Lipemia was slight to marked in healthy lipemic MS, and marked in diabetic ones. All DOB had clear plasma; 8 were healthy and 3 had diabetes. All healthy lipemic MS and diabetic lipemic MS had hypertriglyceridemia associated with excess very low density lipoproteins. Chylomicronemia was present in 4 of 6 healthy lipemic MS and all 3 diabetic lipemic MS. Lipoproteins with ultracentrifugal and electrophoretic characteristics of normal low density lipoprotein were lacking in 4 of 6 healthy lipemic MS. The lipoprotein patterns of 4 of 11 healthy nonlipemic MS were characterized by mild hypertriglyceridemia associated with increased very low density lipoproteins and a lack of lipoproteins with characteristics of normal low density lipoproteins. Lipoprotein patterns of diabetic DOB closely resembled those of healthy DOB; those of diabetic lipemic MS resembled those of markedly lipemic healthy lipemic MS. In conclusion, the hyperlipoproteinemia of Miniature Schnauzers is characterized by increased very low density lipoproteins with or without accompanying chylomicronemia; some affected dogs may have decreased low density lipoproteins. (Journal of Veterinary Internal Medicine 1993; 7:253–260. Copyright © 1993 by the American College of Veterinary Internal Medicine.)