Plasma amino acid concentrations in 36 dogs with histologically confirmed superficial necrolytic dermatitis

Serum Amino Acid Profiles in Dogs with a Congenital Portosystemic Shunt

Background/Objectives: A functional liver is vital for normal protein metabolism. Alterations of circulating amino acid (AA) concentrations have previously been reported in dogs with hepatocellular carcinoma, chronic hepatitis, and hepatocutaneous syndrome. The purpose of this study was to compare serum AA profiles between dogs with a congenital portosystemic shunt (CPSS) and healthy control dogs. Methods: Serum samples were collected from 50 dogs with an extrahepatic congenital portosystemic shunt (eCPSS) and 10 dogs with an intrahepatic congenital portosystemic shunt (iCPSS) at time of surgical intervention and from 21 healthy control dogs. Serum AA and other nitrogenous compounds were measured with a dedicated amino acid analyzer. The concentration of each AA was compared between groups using a Kruskal-Wallis test followed by Dunn's multiple comparisons tests, as appropriate. The Benjamini-Hochberg procedure was used to control for false discovery. Significance was set at q < 0.05. Results: Compared to healthy controls, dogs with a CPSS had significantly increased serum concentrations of ammonia, asparagine, glutamic acid, histidine, phenylalanine, serine, and tyrosine and had significantly decreased concentrations of isoleucine, leucine, threonine, urea, and valine. There were no significant differences in serum AA concentrations between dogs with an eCPSS and dogs with an iCPSS. Conclusions: Dogs with a CPSS had altered serum AA concentrations compared to healthy control dogs, including decreased branched-chain amino acids (BCAAs) and increased aromatic amino acids (AAAs). In summary, serum AA profiles can differentiate dogs with a CPSS from healthy dogs but not dogs with an eCPSS from dogs with an iCPSS.

Plasma amino acid profiles of dogs with the hepatocutaneous syndrome and dogs with other chronic liver diseases

BACKGROUND

Dogs with hepatocutaneous syndrome (HCS) have marked plasma hypoaminoacidemia, but its occurrence in dogs with chronic liver diseases not associated with HCS (non-HCS CLD) is unknown.

OBJECTIVES

To determine if plasma hypoaminoacidemia occurs in dogs with non-HCS CLD, compare plasma amino acid (PAA) profiles between dogs with non-HCS CLD and HCS, and define a sensitive and specific PAA pattern for diagnosing HCS.

ANIMALS

Data were collected from client-owned dogs, a prospective cohort of 32 with CLD and 1 with HCS, and a retrospective cohort of 7 with HCS.

METHODS

Prospective study. Dogs with chronic serum liver enzyme increases were recruited after hepatic biopsy. Plasma amino acid profiles were measured using high-performance liquid chromatography. Plasma amino acid concentrations were compared between dogs with non-HCS CLD and HCS. Regression analysis was performed to identify a unique PAA pattern for HCS diagnosis.

RESULTS

Twelve dogs each with vacuolar hepatopathy or chronic hepatitis and 8 dogs with congenital disorders (primary hypoplasia of the portal vein or ductal plate malformations) were enrolled. Compared to non-HCS CLD dogs, HCS dogs had significantly lower plasma concentrations of several amino acids. Regression analysis revealed that glutamine, glycine, citrulline, arginine, and proline concentrations less than 30% of the mean reference value had 100% sensitivity, specificity for diagnosing HCS.

CONCLUSIONS AND CLINICAL IMPORTANCE

Generalized plasma hypoaminoacidemia does not accompany non-HCS CLD. Concentrations of 5 specific amino acids less than 30% of the mean reference value can serve as a noninvasive biomarker for diagnosing HCS.

Non-Invasive Paraclinical Diagnosis of Hepatocutaneous Syndrome in a Dog

A 14-year-old, female spayed Bichon Maltese with no other known previous pathologies was presented for dermatological examination after being referred from a private clinic with the suspicion of generalized, treatment-resistant demodicosis. Upon presentation and clinical examination, multiple deep skin scrapings were performed, returning negative parasitological results. Complete blood count and serum biochemistry revealed mild hepatic damage. Abdominal ultrasound revealed an abnormal echostructure of the liver displaying a honeycomb or Swiss cheese-like pattern, reported as pathognomonic for hepatocutaneous syndrome. The owner declined any further paraclinical examination, including skin biopsy and histopathological examination, requesting a treatment protocol that could be pursued at home, considering the age of the dog and its reactive behavior during the examination. The present case report highlights a non-invasive method of diagnosing the hepatocutaneous syndrome in a dog by clinical examination, routine blood testing, and ultrasound assessment of the abdomen, in the absence of the possibility of doing a histopathological diagnosis.

Treatment of Superficial Necrolytic Dermatitis with Copper Chelationina Dog with Copper-Associated Hepatitis

A 7 yr old castrated male Cavalier King Charles spaniel presented for evaluation of liver enzyme elevations. Abdominal ultrasound revealed a small liver with mixed echogenicity, small hypoechoic nodules, and an irregular surface. Histologic examination and copper quantification of the liver obtained by laparoscopy diagnosed copper-associated hepatitis. One month later the dog developed hyperkeratosis of all four foot pads and ulcerations of feet, legs, and rectum. Punch biopsies confirmed superficial necrolytic dermatitis. After a total of 2 mo of chelation with no changes to medications, skin lesions began to improve, continuing over the following 6 wk to almost complete resolution. At this point the skin lesions returned and had minimal response to four amino acids infusions. The dog was switched from penicillamine to trientine. Zinc acetate was initiated 6 wk after the switch to trientine, and skin improvement was noted soon thereafter. At the time of death, skin lesions were improving and the dog was clinically comfortable. Copper-associated hepatitis should be considered as a possible etiology for superficial necrolytic dermatitis. Treatment of superficial necrolytic dermatitis is often unrewarding, and copper chelation, when copper-associated hepatitis has been confirmed, represents another therapeutic option.

Plasma Amino Acid Concentration in Obese Horses with/without Insulin Dysregulation and Laminitis

Laminitic horses commonly suffer from an endocrine disease such as equine metabolic syndrome. Hyperinsulinemia is considered a key factor in the pathogenesis of laminitis. Since insulin also affects protein turnover in the body, the resting plasma amino acid concentrations of obese horses that were presented for a combined glucose insulin test (CGIT) were determined. In total, 25 obese horses and two lean horses with recurrent laminitis underwent a CGIT. Of these, five were not insulin dysregulated (obese), 14 were insulin dysregulated (ID), and eight were insulin-dysregulated and laminitic (IDL). Significant differences in the resting concentrations between obese and insulin dysregulated and laminitic (citrulline p = 0.038, obese: 73.001 ± 12.661 nmol/mL, IDL: 49.194 ± 15.486 nmol/mL; GABA p = 0.02, obese: 28.234 ± 3.885 nmol/mL, IDL: 16.697 ± 1.679 nmol/mL; methionine p = 0.018, obese: 28.691 ± 5.913 nmol/mL, IDL: 20.143 ± 3.09 nmol/mL) as well as between insulin dysregulated individuals with and without laminitis (GABA p < 0.001, ID: 28.169 ± 6.739 nmol/mL) regarding three amino acids were determined. This may be an interesting approach, especially for diagnostic testing and possibly also for the feed supplements of horses at risk of developing laminitis. However, further research, including a higher number of cases, is required.

Treatment and outcomes of dogs with hepatocutaneous syndrome or hepatocutaneous-associated hepatopathy

BACKGROUND

Superficial necrolytic dermatitis (SND) in dogs is a rare disorder most commonly associated with hepatocutaneous syndrome. Although often reported as fatal, sporadically reported long-term remissions might be more common than previously believed and linked to treatment regimens.

HYPOTHESIS/OBJECTIVES

Evaluate treatments and associated outcomes in dogs with hepatocutaneous-associated hepatopathy (HCH) with or without SND, designated collectively aminoaciduric canine hypoaminoacidemic hepatopathy syndrome (ACHES).

ANIMALS

Forty-one dogs of various breeds and ages diagnosed with ACHES.

METHODS

Retrospective study. Electronic surveys, medical records (2014-2019), and communication with veterinarians provided data. Three treatment categories were each dichotomized: IV amino acid (IV-AA) infusions (≥2 vs <2), supplements including S-adenosylmethionine (SAMe), arginine with ornithine, glutathione, lysine, proline, omega-3 fatty acids, or zinc (≥3 vs <3), and diet type (home-cooked vs commercial). Optimal treatment was defined as receiving ≥2 IV-AA treatments, ≥3 nutritional supplements, and a home-cooked diet.

RESULTS

Most dogs (29/41, 71%) received IV-AA infusions (23/29, ≥2 infusions). Twenty-one dogs (51%) were fed commercial diets; 17/41 (41%) were fed home-cooked diets. Most dogs received SAMe (32/41, 78%) and a median of 3 supplements. In 4 dogs, HCH remission occurred. Overall all-cause median survival time (MST) was 359 days, and disease-specific MST was 557 days (range, 1-1783 days). Optimally treated dogs (n = 9) lived significantly longer (MST, >1783 days, P = .02) than variably treated dogs (MST, 214 days).

CONCLUSIONS AND CLINICAL IMPORTANCE

Optimized ACHES management can resolve SND and HCH and confer long-term survival.

Clinical features and amino acid profiles of dogs with hepatocutaneous syndrome or hepatocutaneous-associated hepatopathy

BACKGROUND

Superficial necrolytic dermatitis (SND), hepatocutaneous-associated hepatopathy (HCH), aminoaciduria, and hypoaminoacidemia define hepatocutaneous syndrome (HCS) in dogs. Dogs without SND but that possess all other syndrome components are not well described.

HYPOTHESIS/OBJECTIVES

To define an inclusive syndrome, aminoaciduric canine hypoaminoacidemic hepatopathy syndrome (ACHES) for dogs with HCH or HCS. Compare clinical features, salient clinicopathologic variables, and plasma and urine amino acid (AA) profiles among ACHES cases by skin lesion status.

ANIMALS

Dogs of various breeds and ages diagnosed with ACHES (n = 41). A control (CON) cohort (n = 12) provided AA profile data.

METHODS

Retrospective case series. Available medical records of previously identified cases were reviewed for salient clinical features and clinical pathology data. Plasma and urine AA profiles were performed. Cutaneous lesion status was classified as none, mild, or fulminant.

RESULTS

Thirty cases (73%) developed SND at some time. Dogs with fulminant skin lesions at diagnosis (n = 22/41, 54%) had significantly lower hematocrit (P = .05) and mean corpuscular volume (P = .01) than dogs without SND. Principal component analysis of plasma AA profiles identified distinct clustering of CON from ACHES dogs, but not by skin lesion status. Plasma 1-methylhistidine (<7 nmol/mL) and cystathionine (<7.5 nmol/mL) were robust ACHES biomarkers. Urine lysine (>344 nmol/mg creatinine) and methionine (>68 nmol/mg creatinine) also were useful ACHES biomarkers.

CONCLUSIONS AND CLINICAL IMPORTANCE

Specific AA biomarkers provide additional diagnostic utility in ACHES. Data suggests that HCH is an early stage, and SND a later stage manifestation of ACHES.

Approach to the Diagnosis of Hepatocutaneous Syndrome in Dogs: A Retrospective Study and Literature Review

Superficial necrolytic dermatitis (SND) is a rare and often fatal disease in dogs that has been associated with pancreatic neuroendocrine neoplasia (SND/EN) and hepatocutaneous syndrome (SND/HCS). Although various combinations of diagnostics have been used to differentiate these two causes of SND, there are currently no data on which combination would enable the most timely and noninvasive way to diagnose HCS. Medical records were reviewed retrospectively (2004-2018) for dogs with SND/HCS (n = 24) and SND/EN (n = 1). These data were compared with cases found by review of the literature of dogs with SND/HCS (n = 105) and SND/EN (n = 13). The most consistent findings with SND were dermatological lesions affecting paw pads or mucocutaneous junctions (143/143, 100%) and marked plasma hypoaminoacidemia (58/58, 100%). On ultrasound, a honeycomb liver was seen in 62/63 (98%) dogs with SND/HCS but none with SND/EN. Six out of 23 (26%) dogs in the retrospective study with SND/HCS had marked keratinocyte apoptosis, a finding that was associated with diabetes mellitus. This study suggests that in dogs with characteristic skin lesions, an amino acid profile permits a noninvasive diagnosis of SND. An abdominal ultrasound can then assist in the differentiation of SND/HCS and SND/EN.

Plasma amino acid profiles in dogs with closed extrahepatic portosystemic shunts are only partially improved 3 months after successful gradual attenuation

BACKGROUND

Dogs with portosystemic shunts have an altered blood amino acid profile, with an abnormal branched-chained amino acid (BCAA)-to-aromatic amino acid (AAA) ratio being the most common abnormality. Different liver diseases have distinctive amino acid profiles.

OBJECTIVES

Determine the changes in plasma amino acid profiles in dogs with extrahepatic portosystemic shunts (EHPSS) from diagnosis to complete closure.

ANIMALS

Ten client-owned dogs with EHPSS closed after surgical attenuation.

METHODS

Prospective cohort study. Medical treatment was instituted in dogs diagnosed with EHPSS. At least 4 weeks later, gradual surgical attenuation was performed. Three months postoperatively, EHPSS closure was confirmed by transsplenic portal scintigraphy. Clinical signs were scored and blood was taken before institution of medical treatment, at time of surgery, and 3 months postoperatively. At the end of the study, the plasma amino acid profiles were analyzed in batch.

RESULTS

The median BCAA-to-AAA ratio was extremely low (0.6) at time of diagnosis and remained low (0.5) at time of surgery, despite the fact that median neurological score significantly improved from 22 to 2 after starting medical treatment (P = .04). Three months after surgical attenuation, a significantly higher BCAA-to-AAA ratio (1.5) was observed (P < .001).

CONCLUSIONS AND CLINICAL IMPORTANCE

Medical treatment does not improve the BCAA-to-AAA ratio in dogs with EHPSS, despite substantial clinical improvement. Although the ratio significantly increased after EHPSS closure, it was still indicative of moderate to severe hepatic dysfunction in all dogs.

Impact of storage temperature, storage duration, and deproteinization on plasma amino acid concentrations in dogs

Reliability of canine plasma amino acid analysis depends on sample stability which can be influenced by pre-analytical handling techniques, storage temperature, storage time, and deproteinization status. Extrapolating data to dogs from research in other species is limited given discordant methodology and interspecies differences. The present study investigated the effects of deproteinization status (non-deproteinized or deproteinized) and storage temperature (at -20 °C or - 80 °C) on the concentration of 22 canine plasma amino acids during a 300-day storage period. Storage time had a significant effect (p < 0.05) of overall declining concentration of most amino acids. Compared to non-deproteinized samples, deproteinization contributed to overall higher concentrations of cyst(e)ine and glutamic acid, and consistently modified the effect of storage time and temperature on cyst(e)ine, glutamic acid, and glutamine. Compared to -20 °C, storage at -80 °C contributed to a higher concentration of cyst(e)ine and glutamic acid, and modified the effect of storage time on arginine, glutamic acid, glutamine, and tryptophan. Storage time had a consistent, significant effect on amino acid concentrations in canine plasma samples. Although sample deproteinization and low storage temperature modified the effect of storage time, these interactions were variable among analyzed amino acids. Therefore, timely sample analysis is recommended. If delayed sample analysis is inevitable, deproteinization should be performed prior to sample banking to preserve amino acid stability.

Plasma amino acid concentrations during experimental hyperinsulinemia in 2 laminitis models

BACKGROUND

Endocrinopathic laminitis develops in association with insulin dysregulation, but the role of insulin in the pathogenesis remains unclear. Hyperinsulinemia can cause hypoaminoacidemia, which is associated with integumentary lesions in other species and therefore warrants investigation as a potential mechanism in laminitis.

OBJECTIVE

Evaluate plasma amino acid concentrations in the euglycemic-hyperinsulinemic clamp (EHC) and prolonged glucose infusion (PGI) laminitis models.

ANIMALS

Sixteen Standardbred horses.

METHODS

Prospective experimental study. Plasma amino acid concentrations were measured in samples collected every 6 hours from horses that underwent a 48-hour EHC (n = 8) or 66-hour PGI (n = 8) after a 24- or 6-hour baseline period in EHC and PGI groups, respectively.

RESULTS

Fifteen of the 20 measured amino acid concentrations decreased over time in both EHC and PGI horses (P < 0.001). The median percentage change from baseline for these amino acids was: histidine (EHC: 41.5%; PGI: 43.9%), glutamine (EHC: 51.8%; PGI: 35.3%), arginine (EHC: 51.4%; PGI: 41%), glutamic acid (EHC: 52.4%; PGI: 31.7%), threonine (EHC: 62.8%; PGI: 25.2%), alanine (EHC: 48.9%; PGI: 19.5%), proline (EHC: 56.2%; PGI: 30.3%), cystine (EHC: 34.9%; PGI: 31.2%), lysine (EHC: 46.4%; PGI: 27.8%), tyrosine (EHC: 27.5%; PGI: 16.9%), methionine (EHC: 69.3%; PGI: 50.8%), valine (EHC: 50.8%; PGI: 34.4%), isoleucine (EHC: 60.8%; PGI: 38.7%), leucine (EHC: 48.2%; PGI: 36.6%), and phenylalanine (EHC: 16.6%; PGI: 12.1%).

CONCLUSIONS AND CLINICAL IMPORTANCE

Hypoaminoacidemia develops in EHC and PGI laminitis models. The role of hypoaminoacidemia in the development of hyperinsulinemia-associated laminitis warrants further investigation.

Amino Acids in Dog Nutrition and Health

The dog has assumed a prominent role in human society. Associated with that status, diet choices for companion dogs have begun to reflect the personal preferences of the owners, with greater emphasis on specialty diets such as organic, vegan/vegetarian, and omission or inclusion of specific ingredients. Despite consumer preferences and many marketing strategies employed, the diets must ensure nutritional adequacy for the dog; if not, health becomes compromised, sometimes severely. The most frequent consideration of consumers and dog food manufacturers is protein source and concentration with a growing emphasis on amino acid composition and bioavailability. Amino acids in general play diverse and critical roles in the dog, with specific amino acids being essential. This review covers what is known regarding amino acids in dog nutrition.

The effect of continuous digital hypothermia on lamellar energy metabolism and perfusion during laminitis development in two experimental models

BACKGROUND

Continuous digital hypothermia (CDH) prevents lamellar failure in the euglycaemic hyperinsulinaemic clamp (EHC) and oligofructose (OF) laminitis models, but the mechanisms remain unclear.

OBJECTIVES

To evaluate the effects of CDH on lamellar energy metabolism and perfusion in healthy horses and during EHC and OF laminitis models.

STUDY DESIGN

In vivo experiment.

METHODS

Archived samples were used from Standardbred geldings that received no treatment (CON) (n = 8) or underwent EHC (n = 8) or OF (n = 6) laminitis models. Both forelimbs were instrumented with a lamellar microdialysis system, and one forelimb was cooled (CDH) with the other maintained at ambient temperature (AMB). Microdialysate was collected every 6 hours and analysed for glucose, lactate and pyruvate concentrations and lactate to pyruvate ratio (L:P). Microdialysis urea clearance was used to estimate lamellar tissue perfusion. Data were analysed using a mixed-effects linear regression model.

RESULTS

Glucose did not change in CDH limbs relative to AMB in CON (P = .3), EHC (P = .3) or OF (P = .6) groups. There was a decrease in lactate (P < .001) and pyruvate (P < .01) in CDH limbs relative to AMB in all groups. L:P decreased in CON CDH relative to CON AMB (P < .001) but was not different in EHC (P = .6) and OF (P = .07) groups. Urea clearance decreased in CDH limbs relative to AMB in CON (P = .002) and EHC (P < .001), but not in OF (P = .4).

MAIN LIMITATIONS

The EHC model may not mimic natural endocrinopathic laminitis.

CONCLUSIONS

CDH caused a marked decrease in lamellar glucose metabolism (CON, EHC and OF) and perfusion (CON and EHC) without affecting lamellar glucose concentration. Although cellular energy failure is not a primary pathophysiological event in EHC and OF laminitis models, CDH may act by limiting energy supply to pathologic cellular processes whilst preserving those critical to lamellar homoeostasis.

Successful Long-Term Management of Canine Superficial Necrolytic Dermatitis With Amino Acid Infusions and Nutritionally Balanced Home-Made Diet Modification

A 10-year old, castrated male, Bichon Frise with a history of hyperadrenocorticism and intrahepatic portal vein hypoplasia was diagnosed with superficial necrolytic dermatitis (SND). The dog exhibited thick crusts on the chin, muzzle, prepuce, and paws. In addition, the dorsal surfaces of all paws were erythematous while the palmar/plantar surfaces were hyperkeratotic, hardened, and painful. The dog was treated with intravenous amino acid infusions (AAI), raw egg yolks, as well as zinc and omega-3 fatty acid oral supplements. The dog required AAI once every 2–3 weeks because this coincided with recrudescence of painful skin lesions. The dog was subsequently diagnosed with diabetes mellitus. A consult with the Nutrition Service was pursued 220 days after the original SND diagnosis because of concern for feeding raw eggs and for malnutrition since appetite was variable, muscle condition was reduced, and greater than 50% of ingested calories were from foods that were not nutritionally complete. There was also concern regarding the variability of the diet and the impact it would have on the management of diabetes mellitus. The diet was prepared by the dog owner according to a provided recipe and presented twice daily. The diet was rich in high quality protein and fat. All other treatments including medications, supplements, and bathing schedule remained unchanged at the time of diet modification. The dog was subclinical for SND associated clinical signs approximately 3 weeks after the diet modification, which also coincided with the last AAI. The AAI was postponed and was next administered 7 weeks later (i.e., 10 weeks from the previous infusion). The dog remained subclinical for SND related clinical signs and continued to receive AAI once every 10–12 weeks until he was euthanized 718 days later for complications related to severe multi-drug resistant, skin infections. In conclusion, this report highlights a novel role for nutritionally balanced home-made diets designed by a board-certified veterinary nutritionist could substantially increase time interval between AAI and outcome in dogs with SND.

Plasma amino acid profiles in dogs with inflammatory bowel disease

BACKGROUND

Lymphocytic-plasmacytic enteritis is the common form of idiopathic inflammatory bowel disease (IBD) in dogs. In human IBD, disturbances of amino acid metabolism have been demonstrated to be involved in the pathophysiology of IBD. Therefore, plasma amino acid profile might represent a novel marker of human IBD.

OBJECTIVES

To determine the plasma amino acid profiles of dogs with IBD and its usefulness as a novel marker of IBD in dogs.

ANIMALS

Fasting blood plasma was obtained from 10 dogs with IBD and 12 healthy dogs.

METHODS

All IBD dogs were prospectively included in this study, and heparinized blood samples were collected. The plasma concentrations of 21 amino acids were determined using the ninhydrin method. The relationships among the plasma amino acid concentrations and plasma C-reactive protein (CRP) concentration, canine chronic enteropathy clinical activity index (CCECAI), and overall World Small Animal Veterinary Association (WSAVA) score were investigated.

RESULTS

Median concentration (nmol/mL) of methionine [46.2; range, 30.0-59.3], proline [119.4; range, 76.7-189.2], serine [115.1; range, 61.4-155.9], and tryptophan [17.4; range, 11.9-56.3]) were significantly lower than in control dogs [62.6; range, 51.0-83.6, 199.1; range, 132.5-376.7, 164.3; range, 124.7-222.9, and 68.3; range, 35.7-94.8, respectively]. A negative correlation was identified between the plasma serine concentration and CCECAI (r _s = -.67, P = .03), but there were no correlations between plasma amino acid concentrations and CRP concentration or overall WSAVA score.

CONCLUSIONS AND CLINICAL IMPORTANCE

Plasma serine concentration might represent a novel maker of IBD in dogs.

Characterization of aminoaciduria and hypoaminoacidemia in dogs with hepatocutaneous syndrome

OBJECTIVE To characterize aminoaciduria and plasma amino acid concentrations in dogs with hepatocutaneous syndrome (HCS). ANIMALS 20 client-owned dogs of various breeds and ages. PROCEDURES HCS was definitively diagnosed on the basis of liver biopsy specimens (n = 12), gross and histologic appearance of skin lesions (4), and examination of skin and liver biopsy specimens (2) and presumptively diagnosed on the basis of cutaneous lesions with compatible clinicopathologic and hepatic ultrasonographic (honeycomb or Swiss cheese pattern) findings (2). Amino acid concentrations in heparinized plasma and urine (samples obtained within 8 hours of each other) were measured by use of ion exchange chromatography. Urine creatinine concentration was used to normalize urine amino acid concentrations. Plasma amino acid values were compared relative to mean reference values; urine-corrected amino acid values were compared relative to maximal reference values. RESULTS All dogs had generalized hypoaminoacidemia, with numerous amino acid concentrations < 50% of mean reference values. The most consistent and severe abnormalities involved glutamine, proline, cysteine, and hydroxyproline, and all dogs had marked lysinuria. Urine amino acids exceeding maximum reference values (value > 1.0) included lysine, 1-methylhistidine, and proline. CONCLUSIONS AND CLINICAL RELEVANCE Hypoaminoacidemia in dogs with HCS prominently involved amino acids associated with the urea cycle and synthesis of glutathione and collagen. Marked lysinuria and prolinuria implicated dysfunction of specific amino acid transporters and wasting of amino acids essential for collagen synthesis. These findings may provide a means for tailoring nutritional support and for facilitating HCS diagnosis.

Long-Term Management with Adipose Tissue-Derived Mesenchymal Stem Cells and Conventional Treatment in a Dog with Hepatocutaneous Syndrome

Hepatocutaneous syndrome (HS) is an uncommon skin disorder that occurs in conjunction with liver disease and is diagnosed based on decreased plasma concentrations of amino acids and the histopathology of skin lesions. The survival period generally is <6 months. A 10-year-old castrated male Maltese dog was presented for evaluation of lethargy, polyuria, polydipsia, and skin lesions including alopecia, erythema, and crusts. Based on increased liver enzyme activity, low plasma amino acid concentrations, and findings from liver cytology and skin biopsy, the dog was diagnosed with HS. In addition to administration of antioxidants, hepatoprotective agents, and amino acids IV, allogenic adipose tissue-derived mesenchymal stem cells were infused 46 times over a 30-month period: 8 times directly into the liver parenchyma guided by ultrasonography and the remainder of the times into peripheral veins. After commencing stem cell therapy, the dog's hair re-grew and the skin lesions disappeared or became smaller. During ongoing management, the patient suddenly presented with anorexia and uncontrolled vomiting, and severe azotemia was observed. The dog died despite intensive care. On necropsy, severe liver fibrosis and superficial necrolytic dermatitis were observed. The dog survived for 32 months after diagnosis. A combination of amino acid and stem cell therapy may be beneficial for patients with HS.

Localized parakeratotic hyperkeratosis in sixteen Boston terrier dogs

BACKGROUND

Although zinc responsive dermatosis is typically a disorder of Arctic breed dogs, this study identifies similar cutaneous lesions on the face and pressure points of Boston terrier dogs.

HYPOTHESIS/OBJECTIVES

To document the clinical and histological features of localized parakeratotic hyperkeratosis of Boston terrier dogs, to determine if the lesions respond to zinc supplementation and to determine whether tissue zinc levels were decreased in affected versus unaffected dogs.

MATERIAL AND METHODS

Sixteen Boston terrier dogs with similar gross and histological findings were identified retrospectively from two institutions. Follow-up information for nine dogs from one institution was obtained from referring veterinarians using a questionnaire. Tissue zinc levels were measured from formalin-fixed paraffin-embedded skin biopsy samples of affected and unaffected dogs using inductively coupled plasma mass spectrometry.

RESULTS

Mild to severe parakeratotic hyperkeratosis with follicular involvement was present in all 16 cases. Of the nine dogs for which follow-up information was available, five dogs received oral zinc supplementation and four dogs had documented clinical improvement or resolution of dermatological lesions. The median skin zinc levels were not significantly different between affected and unaffected dogs.

CONCLUSIONS AND CLINICAL IMPORTANCE

To the best of the authors' knowledge this is the first report of localized parakeratotic hyperkeratosis in Boston terrier dogs, some of which improved with oral zinc supplementation. Prospective studies in Boston terrier dogs are warranted to document potential zinc deficiency (serum and/or tissue levels, pre- and post-treatment) and to objectively assess response to zinc supplementation and other therapies.

Hepatocutaneous syndrome in Shih Tzus: 31 cases (1996-2014)

OBJECTIVE

To characterize findings in Shih Tzus with progressive superficial necrolytic dermatitis and degenerative vacuolar hepatopathy consistent with hepatocutaneous syndrome.

DESIGN

Retrospective case series.

ANIMALS

31 Shih Tzus.

PROCEDURES

Medical records were reviewed to obtain information on signalment, history, treatment, outcome, and results of clinicopathologic testing, abdominal ultrasonography, and histologic examination of skin and liver specimens. A pedigree analysis was performed.

RESULTS

There were 16 males and 15 females. Median age at the time of diagnosis was 8 years (range, 5 to 14 years). Common clinical signs included lethargy, inappetence, weight loss, and lameness. Twenty-five dogs had cutaneous lesions consistent with hepatocutaneous syndrome; the remaining 6 initially only had hepatic abnormalities, but 3 of the 6 subsequently developed cutaneous lesions. Common clinicopathologic abnormalities included microcytosis (15/24 [63%] dogs) and high serum alkaline phosphatase activity (24/24 [100%] dogs). Hepatic ultrasonographic findings included a hyperechoic or heteroechoic appearance to the parenchyma with innumerable hypoechoic nodules. Histologic hepatic lesions consisted of degenerative vacuolar (glycogen and lipid) hepatopathy associated with minimally fibrotic to nonfibrotic, noninflammatory, proliferative nodules. Pedigree analysis confirmed a common ancestry in 12 of 18 dogs. Median survival time was 3 months (range, 1 to 36 months).

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that HCS may have a heritable component in Shih Tzus, although the condition may also be identified in Shih Tzus without affected relatives. Clinical, clinicopathologic, ultrasonographic, and histologic abnormalities in affected Shih Tzus were similar to those previously reported for dogs of other breeds with HCS.

Circadian and postprandial variation in plasma citrulline concentration in healthy dogs

OBJECTIVE

To evaluate circadian and postprandial variations in plasma citrulline concentration in healthy dogs.

ANIMALS

8 healthy Beagles.

PROCEDURES

Blood samples were collected from dogs after 12 hours of food withholding (0 hours; 8:00 am) and then every 2 hours for 12 hours (until 8:00 pm) and again at 24 hours (8:00 am the next day). The same protocol was repeated, with the only difference being that a meal was given immediately after the 0-hour sample collection point. Plasma citrulline concentration was measured by ion exchange chromatography.

RESULTS

No significant difference in plasma citrulline concentration was identified among measurement points when food was withheld. Mean ± SD plasma citrulline concentration at 4 hours (72.2 ± 12.7 μmol/L) and 24 hours (56.1 ± 12.5 μmol/L) after dogs were fed was significantly different from that at 0 hours (64.4 ± 12.7 μmol/L).

CONCLUSIONS AND CLINICAL RELEVANCE

Plasma citrulline concentration had no circadian variation in unfed dogs but increased significantly in fed dogs 4 hours after a meal. Therefore, food should be withheld from dogs for 8 to 12 hours before blood sample collection for measurement of citrulline concentration.

Hypoaminoacidemia is not associated with ulcerative lesions in black rhinoceroses, Diceros bicornis

Ulcerative oral and skin lesions have become an issue of concern for the health of the managed black rhinoceros (rhino) (Diceros bicornis) populations. Lesions exhibited by the black rhino are clinically similar to those observed in other species with superficial necrolytic dermatitis (SND). One biochemical alteration in dogs with SND is severe hypoaminoacidemia, and nearly all cases are fatal. The objective of this study was to determine if black rhinos with analogous lesions exhibit a similar hypoaminoacidemia. Amino acid concentrations were measured in monthly plasma samples collected for 1 yr from black rhinos with (n = 4) and without (n = 34) lesions clinically consistent with SND. The rhinos with skin and/or oral lesions were zoo born males, ages 2, 6, 17, and 23 yr, from four different facilities. Three rhinos recovered from skin (n = 2) and oral lesions (n = 1). However, the one male with both skin and oral lesions died with the disease. None of the affected black rhinos exhibited a decrease in any of the amino acids evaluated or for total amino acid concentrations (P > 0.05). Based on the absence of hypoaminoacidemia and the comparatively low mortality rate in rhinos with lesions, it appears that this syndrome is not entirely consistent with SND observed in other species. These data will be useful for future assessments of rhino nutritional status and other potential metabolic diseases.

Relationship among plasma amino acids, C-reactive protein, illness severity, and outcome in critically ill dogs

BACKGROUND

Alterations in circulating amino acids have been documented in animal models and in critically ill people but have not been evaluated in dogs with spontaneously occurring disease.

HYPOTHESIS/OBJECTIVES

To compare amino acid concentrations in critically ill dogs and healthy controls and to investigate potential relationships among amino acids, markers of inflammation, illness severity, and clinical outcome.

ANIMALS

Forty-eight critically ill dogs and 24 healthy control dogs.

METHODS

Plasma was analyzed for amino acids and C-reactive protein (CRP) was measured in serum. The Fischer ratio (the molar ratio of branched chain amino acids [BCAA] to aromatic amino acids [AAA]) and survival prediction index (SPI2) were calculated.

RESULTS

Median CRP concentrations were significantly higher in the critically ill dogs compared with controls (P < .001). Critically ill dogs had significantly lower concentrations of alanine (P= .001), arginine (P < .001), citrulline (P < .001), glycine (P < .001), methionine (P < .001), proline (P < .001), and serine (P= .001) but significantly higher concentrations of lysine (P= .02) and phenylalanine (P < .001; Table 1). This pattern resulted in a significantly lower Fischer ratio (P= .001) in the critically ill group. Median SPI2 score was significantly higher in dogs that survived (P= .03). Concentrations of arginine (P= .02), isoleucine (P= .01), leucine (P= .04), serine (P= .04), valine (P= .04), total BCAA (P= .03), and the Fischer ratio (P= .03) were significantly higher in survivors compared with nonsurvivors.

CONCLUSIONS AND CLINICAL IMPORTANCE

Critically ill dogs have altered amino acid profiles and additional research to investigate potential benefits of amino acid supplementation is warranted.

Síndrome do gucagonoma em cão

O eritema necrolítico migratório é rara dermatose caracterizada por lesões erodo-ulcerativas e crostosas em áreas intertriginosas, junções mucocutâneas, superfícies articulares e de apoio crônico, que tem sido descrita em seres humanos, cães, gatos e rinocerontes. Sua etiologia tem sido relacionada a neoplasias pancreáticas, mormente das células alfa produtoras de glucagon, e a graves doenças do parênquima hepático ou gastroentérico. Relata-se o caso de um cão com necrose epidérmica metabólica secundária a glucagonoma, que apresenta fortes similaridades com a síndrome do glucagonoma em humanos.

Metabolic epidermal necrosis in a dog associated with pancreatic adenocarcinoma, hyperglucagonaemia, hyperinsulinaemia and hypoaminoacidaemia

A case of metabolic epidermal necrosis associated with a pancreatic carcinoma is described. Normoglycaemia, reduced serum fructosamine, and hypoaminoacidaemia were identified. Hyperinsulinaemia and hyperglucagonaemia were documented. Immunohistochemistry documented strong tumour expression of both insulin and glucagon supporting combined paraneoplastic production of both hormones by the tumour. Enteral protein and fatty acid supplementation and parenteral amino acid supplementation proved ineffective. Metastasis to regional lymph nodes was identified and the patient was euthanased.

Differences in taurine synthesis rate among dogs relate to differences in their maintenance energy requirement

Diet-induced (taurine deficiency) dilated cardiomyopathy is reported more in large than small dogs possibly because taurine biosynthesis rate (TBR) is lower in large than small dogs. The TBR in 6 mongrels (37.9 +/- 2.1 kg) and 6 beagles (12.8 +/- 0.4 kg) was determined from the fractional dilution rate of urinary [1,2-(2)H(2)]-taurine, (d4-tau). All dogs were given a 15.6% protein, 0.60% sulfur amino acid (SAA) diet in amounts to maintain an ideal body condition score. After 3 mo, 14.6 mg/kg body weight of d4-tau was given orally and TBR determined from d4-tau to taurine ratio in urine collected each d for 6 d. Enrichments of d4-tau were determined by GC-MS. Thereafter, mongrels and beagles were paired by ranking of SAA intake per metabolic body weight per kg(0.75). Each pair received the same amount of diet/kg(0.75) for 2 wk, then TBR was again determined. Concentrations of taurine in plasma, blood, and urine and concentrations of plasma thiols were measured during each TBR determination. In Expt. 1, TBR and taurine concentrations in plasma and urine of mongrels were lower (P < 0.05) than those of beagles. In Expt. 2, TBR and taurine concentrations in blood and plasma of mongrels were lower (P < 0.05) than beagles. Together, the results support the hypothesis that large compared with small dogs have lower TBR when fed diets near-limiting in dietary SAA, but adequate to maintain ideal body condition.

Effects of dietary supplementation of DL-methionine or 2-hydroxy-4-(methylthio)-butanoic acid on food intake, nutrient digestibility, nitrogen balance, and urinary and blood metabolites in healthy, growing dogs

The aim of this study was to evaluate effects on nutritional responses of supplemental DL-methionine and 2-hydroxy-4-(methylthio) butanoic acid (HMTBA) in a commercial-type diet in growing dogs. A nitrogen balance study was conducted as a randomized complete block design using 30 Pointer puppies (72-d-old; 5.5 kg). A corn and poultry byproduct meal based diet was supplemented with 0.1 or 0.2% DL-methionine or HMTBA on an equimolar basis. Organic matter and gross energy tended (p < 0.10) to be less digestible by dogs fed the 0.1% HMTBA diet compared with the 0.2% DL-methionine diet, but other nutrients were unaffected. Postprandial urinary calcium tended (p < 0.10) to be lower for the basal and HMTBA treatments. Fecal ammonia tended (p < 0.10) to be lower for the 0.1% HMTBA diet than for the 0.2% DL-methionine diet. At the levels tested, DL-methionine and HMTBA appear to act similarly when included in a corn and poultry by-product meal diet fed to young dogs.

Pyrroloquinoline quinone nutritional status alters lysine metabolism and modulates mitochondrial DNA content in the mouse and rat

Pyrroloquinoline quinone (PQQ) added to purified diets devoid of PQQ improves indices of perinatal development in rats and mice. Herein, PQQ nutritional status and lysine metabolism are described, prompted by a report that PQQ functions as a vitamin-like enzymatic cofactor important in lysine metabolism (Nature 422 [2003] 832). Alternatively, we propose that PQQ influences lysine metabolism, but by mechanisms that more likely involve changes in mitochondrial content. PQQ deprivation in both rats and mice resulted in a decrease in mitochondrial content. In rats, alpha-aminoadipic acid (alphaAA), which is derived from alpha-aminoadipic semialdehyde (alphaAAS) and made from lysine in mitochondria, and the plasma levels of amino acids known to be oxidized in mitochondria (e.g., Thr, Ser, and Gly) were correlated with changes in the liver mitochondrial content of PQQ-deprived rats, but not PQQ-supplemented rats. In contrast, the levels of NAD dependent alpha-aminoadipate-delta-semialdehyde dehydrogenase (AASDH), a cytosolic enzyme important to alphaAA production from alphaAAS, was not influenced by PQQ dietary status. Moreover, the levels of U26 mRNA were not significantly changed even when diets differed markedly in PQQ and dietary lysine content. U26 mRNA levels were measured, because of U26's proposed, albeit questionable role as a PQQ-dependent enzyme involved in alphaAA formation.

Pyrroloquinoline quinone modulates mitochondrial quantity and function in mice

When pyrroloquinoline quinone (PQQ) is added to an amino acid-based, but otherwise nutritionally complete basal diet, it improves growth-related variables in young mice. We examined PQQ and mitochondrial function based on observations that PQQ deficiency results in elevated plasma glucose concentrations in young mice, and PQQ addition stimulates mitochondrial complex 1 activity in vitro. PQQ-deficient weanling mice had a 20-30% reduction in the relative amount of mitochondria in liver; lower respiratory control ratios, and lower respiratory quotients than PQQ-supplemented mice (2 mg PQQ/kg diet). In mice from dams fed a conventional laboratory diet, but switched at weaning to the basal diet, plasma glucose, Ala, Gly, and Ser concentrations were elevated at 4 wk (PQQ- vs. PQQ+), but not at 8 wk. The relative mitochondrial content (ratio of mtDNA to nuclear DNA) also tended (P<0.18) to be lower (PQQ- vs. PQQ+) at 4 wk, but not at 8 wk. PQQ also counters the mitochondrial complex 1 inhibitor, diphenylene iodonium (DPI). Mice were gavaged with 0, 0.4, or 4 microg PQQ/g body weight (BW) daily for 14 d. At each PQQ level, DPI was injected (i.p.) at 0, 0.4, 0.8, or 1.6 microg DPI/g BW. The PQQ-deficient mice exposed to 0.4 or 4.0 microg DPI/g lost weight and had lower plasma glucose levels than PQQ-supplemented mice (P<0.05). In addition, fibroblasts took up (3)H-PQQ added to cell cultures, and cultured hepatocytes maintained mitochondrial PQQ concentrations similar to those observed in vivo. Collectively, these results indicate that dietary PQQ can influence mitochondrial amount and function, particularly in perinatal and weanling mice.

Manifestations cutanées des maladies internes du chien

Les manifestations cutanées des maladies internes commencent à être bien connues chez le chien, même si leur étiologie et leur pathogénie ne sont pas toujours élucidées. Elles sont d'une très grande diversité clinique et en relation avec des maladies internes variées. Leur connaissance est importante car ces lésions cutanées entrent dans de nombreux diagnostics différentiels et apparaissent, pour certaines, précocement avant les symptômes de la maladie interne sous-jacente. Enfin, certaines de ces manifestations cutanées constituent des syndromes paranéoplasiques cutanés. Sont envisagées la dermatofibrose nodulaire, l'érythème nécrolytique migrant, la dermatomyosite, les calcinoses, les amyloses, les xanthomes cutanés, le syndrome d'automutilation podale et le syndrome syringomyélie.

Cutaneous paraneoplastic syndromes in dogs and cats: a review of the literature

Cutaneous paraneoplastic syndromes are a group of noncancerous dermatoses associated with internal malignancy. Their recognition can facilitate detection and timely treatment of underlying cancer. More than 30 such disorders have been identified in the human scientific literature, whereas only a few are described in veterinary medicine. This may reflect a lower incidence in animals than in people or may be the result of failure to recognize an association between certain skin lesions and neoplasia. Establishing a relationship between a cutaneous disorder and neoplasia can be difficult unless the skin lesions are rare and almost always associated with a particular tumour type, as is the case for most recognized veterinary paraneoplastic dermatoses. Among these are feline paraneoplastic alopecia, feline thymoma-associated exfoliative dermatitis, nodular dermatofibrosis, feminization syndrome associated with testicular tumours, superficial necrolytic dermatitis and paraneoplastic pemphigus. The aetiology of most cutaneous paraneoplastic syndromes has remained elusive in both people and animals.