Key considerations in the approach to congenital heart disease in dogs and cats.

Congenital heart disease is an important subset of all cardiovascular disease in dogs and cats that is present at birth and most often detected in young animals but can be diagnosed in adulthood. The range of abnormalities that can occur during development of the heart is vast incorporating simple and complex defects, varying degrees of severity and clinical presentations that include heart failure and cyanosis. While some defects do not result in morbidity in an individual animal, others cause severe clinical signs and death at a young age. Advances in imaging and expanding treatment options offer increasingly more possibilities in the diagnosis and management of congenital heart disease which is the focus of this review. The objective is to provide a broad overview of current practice and highlight key aspects to guide practitioners in their approach to congenital heart disease diagnosis and knowledge of available treatment options.

Genetic cause for congenital methemoglobinemia in an Australian Pomeranian dog.

Little is known about genetic causes of congenital methemoglobinemia in dogs. Here, we report a CYB5 R3 mutation in a Pomeranian dog with congenital methemoglobinemia. A 6-year-old neutered female Pomeranian dog was investigated for cyanosis noticed during anesthesia for an orthopedic procedure. The history included lifelong mild exercise intolerance and bluish tongue. Methemoglobinemia was diagnosed using co-oximetry. The CYB5 R3 gene was analyzed by comparing the patient's genomic DNA with the reference canine sequence. Mutation functional significance was investigated using snpEff and multispecies protein homology analyses. A homozygous missense single nucleotide CYB5 R3 mutation (ATC ➔ CTC at codon 194) caused a p.Ile194Leu substitution. The pIle194 residue is highly conserved in other mammals, supporting the likely pathogenicity of the substitution. The mutation described here is identical to that associated with familial methemoglobinemia in a family of Japanese Pomeranian dogs. This observation, together with the homozygous mutation found in our case, indicates that the mutant allele may be widespread within the Pomeranian breed internationally.

Transcatheter closure of a small atrial septal defect with an Amplatzer™ patent foramen ovale occluder in a working dog with cyanosis and exercise intolerance at high altitude.

A 6.5-year-old male Border Collie presented for transcatheter closure of an atrial septal defect due to exercise intolerance and cyanosis while working and training at altitude. A small, left-to-right shunting secundum atrial septal defect was confirmed with no evidence of significant right-sided volume overload. Pulmonary hypertension with subsequent right-to-left interatrial shunting occurring during exercise at high altitude was suspected and prompted the closure of the defect due to the dog's continued athletic requirements. The anatomy of the defect prompted use of a patent foramen ovale occluder rather than an atrial septal defect occluder, which was deployed using a combination of fluoroscopic and transesophageal echocardiographic guidance. The owner did not report continued exercise intolerance or cyanosis and the dog's lifestyle and residence at altitude was unchanged.

Morphometric Documentation of a High Prevalence of Left Ventricular Dilated Cardiomyopathy in Both Clinically Normal and Cyanotic Mature Commercial Broiler Breeder Roosters with Comparisons to Market-Age Broilers.

Previous studies documented the common occurrence of transitory cyanosis and echocardiographic aortic insufficiency in mature commercial broiler breeder roosters. During further investigations, we observed a high prevalence of hearts exhibiting extensive dilation of the left ventricle chamber compatible with dilated left ventricular cardiomyopathy present in both cyanotic and normal subpopulations. We conducted quantitative studies focused on documentation of cardiac ventricle parameters by using simple gross morphometric methods performed on formalin-fixed hearts obtained from both clinically normal roosters and those exhibiting variable transitory cyanosis, echocardiographic aortic insufficiency, or both. A high prevalence of often dramatic left ventricular dilation reflected in enlarged left ventricular chamber areas and elevated left ventricle-to-total ventricle area ratios was morphometrically documented. However, no statistically significant differences in the occurrence of ventricular abnormalities were observed between normal and cyanotic roosters. Age-associated changes were also demonstrated by comparative morphometric studies on hearts from normal market-age broilers (average age of 7 wk) and those of mature roosters (average age of 42 wk). Elevation in both left and right ventricular weight-to-total heart weight ratios dramatically increased with aging. In addition, values (average ± SD) for the left ventricle chamber area-to-total ventricle area ratios increased from 3.2 ± 2.0% in broilers up to 10.0 ± 8.8% in roosters. None of the normal broilers studied demonstrated left ventricular volume ratios above 10%, whereas 33% of the roosters had left ventricular volume ratios above 10%, including 13% with ratios of 20% or higher. However, the left ventricle wall area-to-body weight ratios were much closer for the two age groups (0.85 ± 0.18 cm(2)/kg in broilers and 0.79 ± 0.13 cm(2)/kg in roosters). Also, the standard right ventricle-to-total ventricle weight ratio (RV/TV) went from 0.18 ± 0.04 in broilers to 0.25 ± 0.12 in roosters, whereas the left ventricle-to-total ventricle weight ratios were similar for the two age groups (0.74 ± 0.12 and 0.75 ± 0.08 in broilers and roosters, respectively). Our results for RV/TV in normal broilers were similar to the reported values for normal market-age broilers. In contrast, 36% of the roosters had RV/TV above values reported for broilers considered reflective of right ventricular hypertrophy due to pulmonary hypertension, whereas 4% had values above the reported threshold for broilers dying with ascites (ratios greater than 0.0249 and 0.299, respectively). However, ascites was not observed for any of the roosters. Although essentially all cardiac morphometric parameters demonstrated statistically significant correlations with the age-class group comparisons, significance could not be documented for comparisons between cardiomorphometrics and the subjective occurrences of transitory cyanosis or echocardiographic aortic insufficiency.

Canine brachycephalic airway syndrome: pathophysiology, diagnosis, and nonsurgical management.

Canine brachycephalic airway syndrome is a progressive disease that affects many brachycephalic dogs. This article describes the components of this syndrome and focuses on acute emergency management and long-term conservative management of these patients. Surgical management is described in a companion article.

Presumptive benzocaine-induced methemoglobinemia in a slender-tailed meerkat (Suricata suricatta).

An 8-yr-old castrated male slender-tailed meerkat (Suricata suricatta) was anesthetized for physical examination and dental prophylaxis. To facilitate intubation, two short bursts of benzocaine spray were applied topically to the glottis. Shortly thereafter, the meerkat developed a muddy, blue-gray mucous membrane color and low oxygen saturation readings measured via pulse oximetry. Despite positive pressure ventilation and treatment with doxapram, the cyanosis and hypoxemia did not improve. Blood collected during the procedure was noticeably dark brown and a clinical diagnosis of methemoglobinemia was made. Because of persistent cyanosis and prolonged recovery, the meerkat was anesthetized a second time to facilitate treatment for methemoglobinemia via a slow intravenous bolus of methylene blue and subcutaneously administered dextrose. Within 20 min, the tongue and gingival color normalized. This is the first report of methemoglobinemia in this species. Although it is commonly used in small animal practice and in humans undergoing certain endoscopic procedures, and present in numerous over-the-counter preparations, the risk of topical benzocaine inducing methemoglobinemia is well described. Administration of topical benzocaine in all mammalian species, particularly small patients, should be done with caution. If it is utilized in zoo practice, clinicians are encouraged to administer benzocaine judiciously to avoid accidental overdose, and be familiar with the signs of methemoglobinemia and its treatment.

Cianose e metahemoglobinemia associada à deficiência de NADH-metahemoglobina redutase em um cão sob anestesia / Cyanosis and methahemoglobinaemia associated with NADH-methahemoglobin reductase deficiency in a dog under anesthesia

Este estudo relata a ocorrência de cianose em um cão sob anestesia geral. O paciente não apresentava sinal de doençacardíaca ou respiratória, não havia possibilidade de ingestão acidental de agentes oxidantes, resultando então na suspeita demetahemoglobinemia associada à deficiência de NADH-metahemoglobina redutase. Sendo esta confirmada após testesugestivo e confirmação laboratorial por teste específico

This study reports the occurrence of cyanosis in a dog under general anesthesia. The patient didn’t present any sign of heart orrespiratory disease, the accidental ingestion of oxidizers agents wasn’t possible. Therefore resulting the suspicion ofmetahemoglobinemia associated to the deficiency of NADH-metahemoglobina redutase. This was confirmed after suggestivetest and laboratorial specific test

Cardiogenic hypertrophic osteopathy in a dog with a right-to-left shunting patent ductus arteriosus.

A 5-year-old castrated male Shetland Sheepdog was examined because of progressive bilateral hind limb thickening. Cyanosis of the preputial mucous membranes was evident, whereas the oral mucous membranes had a normal color. A well-structured, palisade-like periosteal reaction with no underlying bone destruction was evident on radiographs of the hind limbs. The radiographic changes were consistent with hypertrophic osteopathy (HO). Severe right-sided cardiomegaly was seen on thoracic radiographs, and a diagnosis of patent ductus arteriosus with right-to-left shunting was made by means of echocardiography and contrast echoaortography. The cyanotic heart disease was believed to be the cause of the HO. Hypertrophic osteopathy has been associated with a number of diseases in animals and humans. In humans, congenital heart defects that cause cyanosis are among the most common causes of HO.

Primary intratracheal lymphosarcoma in four cats.

Four cats presented with clinical signs suggestive of respiratory disease, including dyspnea, wheezing, cyanosis, inspiratory stridor, coughing, and gagging. Radiographs revealed intratracheal masses. Bronchoscopy allowed for lesion localization and collection of samples for cytopathological and histopathological evaluation, which confirmed a diagnosis of lymphosarcoma. Cats treated with systemic chemotherapy or radiation were able to achieve complete remission and long-term resolution of clinical signs.

Atypical time course of clinical signs in a dog poisoned by strychnine.

The general health of a German shepherd dog had deteriorated slightly when it was found after being loose for one hour. After 10 hours of observation, the dog showed signs of pain for the first time and signs of poisoning, such as tenseness of muscles, slight opisthotonus, regurgitation, salivation, mydriasis, dyspnoea and cyanosis, were observed; it died 15 minutes after showing the first clinical signs but it had no seizures or tetanic spasms at any time. A postmortem examination did not reveal any pathological changes. A screening test for alkaloids was positive for strychnine (strychnidin-10-one). The presence of strychnine was confirmed and its concentration was determined by gas chromatography/mass spectrometry in urine (728.5 ng/ml) and in the stomach contents (44.6m microg/g). No strychnine was detected in the dog's serum, but traces of brucine (2,3-dimethoxystrychnidin-10-one), the dimethoxy derivative of strychnine, were detected. This case was compared with other strychnine poisonings recorded in the authors' laboratory over the previous six years, taking into account the species, type of samples, the clinical signs and their duration, the postmortem findings, and the concentrations of strychnine. This was the only case to show such an atypical time course of clinical signs.

Effects of preemptive atropine administration on incidence of medetomidine-induced bradycardia in dogs.

OBJECTIVE: To determine the cardiorespiratory effects of preemptive atropine administration in dogs sedated with medetomidine. DESIGN: Randomized crossover trial. ANIMALS: 12 healthy adult dogs. PROCEDURES: Dogs underwent 6 treatments. Each treatment consisted of administration of atropine (0.04 mg/kg [0.018 mg/lb] of body weight, IM) or saline solution (0.9% NaCl, 1 ml, IM) and administration of medetomidine (10, 20, or 40 microg/kg [4.5, 9.1, or 18.2 microg/lb], IM) 10 minutes later. Treatments were administered in random order, with a minimum of 1 week between treatments. Cardiorespiratory effects before and after atropine and medetomidine administration were assessed. Duration of lateral recumbency and quality of sedation and recovery were assessed. RESULTS: Bradycardia (heart rate < 60 beats/min) was seen in all dogs when saline solution was administered followed by medetomidine, and the dose of medetomidine was not associated with severity or frequency of bradycardia or second-degree heart block. However, a medetomidine dose-dependent increase in mean and diastolic blood pressures was observed, regardless of whether dogs received saline solution or atropine. Preemptive atropine administration effectively prevented bradycardia and second-degree heart block but induced pulsus alternans and hypertension. The protective effects of atropine against bradycardia lasted 50 minutes. Blood gas values were within reference limits during all treatments and were not significantly different from baseline values. Higher doses of medetomidine resulted in a longer duration of lateral recumbency. CONCLUSIONS AND CLINICAL RELEVANCE: Preemptive administration of atropine in dogs sedated with medetomidine effectively prevents bradycardia for 50 minutes but induces hypertension and pulsus alternans.

Bacteriological and histological profile of turkeys condemned for cyanosis.

Canadian Food Inspection Agency (CFIA) has adopted the term cyanosis to describe a category of condemnation for poultry that is dark but has no other condemnable lesions. Two case-control studies (n = 30 pairs; n = 65 pairs) of 18-wk-old tom turkeys were conducted. A case was defined as a carcass condemned by the veterinary inspector for cyanosis, and a control carcass was one that passed inspection. Microbiological tests were conducted on samples of Pectoralis major and Gastrocnemius lacteralis. A modified Rappaport Vassiliadis medium was used for Salmonella, and a Petrifilm method was used to assess aerobic counts, coliform counts, and Escherichia coli. The Salmonella (qualitative) test was negative for all cases and controls, and there were no significant differences between the aerobic counts, coliform counts, and E. coli counts of case and control carcasses. Two pathologists conducted a blind histopathological study: there were no lesions compatible with those of septicemia-toxemia, as defined by CFIA and the USDA, nor any significant histopathological differences between the skin, P. major, G. lateralis, kidney, liver, spleen, small intestine, pancreas, lung, and heart of cases and controls. The inter-rater agreement between pathologists ranged from good to excellent (Kappa = 0.7 to 1.0). In the absence of important lesions and microbial contamination, carcasses with this color change alone should be suitable for human consumption.

Risk factors for abattoir condemnation of turkey carcasses due to cyanosis in southern Ontario.

Cyanosis is a category of condemnation for poultry, as defined by Agriculture and Agrifood Canada. A retrospective study to examine the seasonal patterns and trends for turkey cyanosis condemnation was conducted for the years 1987 to 1995 with the use of condemnation records made available by a single abattoir in Ontario. Condemnation for cyanosis had a significant seasonal pattern, with major losses occurring in the colder months (October to March). A prospective longitudinal study was conducted during January to March and October to December 1996 in the same abattoir and the 75 turkey farms that contracted to process their birds through it and all the 913 truckloads of turkeys processed in these two 3-mo periods. The data from this prospective study were used for multivariate modeling of the effects of potential risk factors on the incidence of cyanosis. Risk factors (at P < or = 0.05) included bird type (broiler age turkeys, mature toms, and mature hens compared to toms and hens), ambient temperature (cold: -9.9 to 0.0 C and very cold: < or =-10.0 C compared to mild: >0.0 C), clean-out lot (the last shipped from a poultry house), shipping time > or =8 h, and emaciation (proportion of turkeys in the lot condemned for insufficient muscle mass). The crate density was a sparing factor, and an increase in turkey density during shipping resulted in a lower incidence of cyanosis. This study suggested that the number of turkeys condemned for cyanosis was associated with cold, shipping stress, and subclinical syndromes.

Roaster breast meat condemned for cyanosis: a dark firm dry-like condition?

A case-control study (n = 68) of roaster chickens condemned for cyanosis was conducted. Color (CIE L*a*b*) and pH were measured at slaughter, and after 24 h aging on ice, at four predetermined sites of the Pectoralis major. Cyanotic carcasses (dark) had a higher pH than controls at the time of slaughter and at 24 h postmortem (P < 0.01). Perimortem pH was significantly correlated with pH at 24 h postmortem (r = 0.64) and also was correlated with lightness (L*) perimortem and postmortem (24 h; r = -0.36 and -0.50, respectively). Perimortem pH was not correlated with meat redness (a*) at slaughter time and after 24 h. Ultimate pH and lightness at 24 h postmortem were also correlated. Tests based on pH, L*, and a* of the P. major were assessed: the sensitivity and specificity at various cut-off points were, respectively, pH(6.3) = 76.47 and 88.24%, L*(41) = 91.18 and 79.41%, and a*(3) = 76.47 and 97.06%. The repeatability (p) of pH and color measurements was excellent and ranged from 0.87 to 0.98. Breast meat from roasters condemned for cyanosis had dark, firm, and dry (DFD)-like traits, and accurate tests based on color and pH could be described as a means of identifying chickens condemned for cyanosis.

A dark, firm dry-like condition in turkeys condemned for cyanosis.

A case-control study (n = 130) was conducted on toms condemned for cyanosis. Color (CIE L*a*b*), pH, and physical characteristics were measured on the Pectoralis major at slaughter and after 24 h. Meat from carcasses condemned for cyanosis had dark, firm, dry-like traits. It was darker and redder and showed higher water-holding capacity, lower cooking loss, and higher gel strength than did controls. Perimortem pH was negatively correlated with the lightness (L*) of meat at the time of slaughter (r = -0.58) and at 24 h postmortem (r = -0.64), positively correlated with water-holding capacity (r = 0.73) and gel strength (r = 0.43) and negatively correlated with cooking loss (r = -0.50). Ultimate pH was negatively correlated with lightness (L*) of meat at slaughter time (r = -0.62) and at 24 h postmortem (r = 0.79) was positively correlated with water-holding capacity (r = 0.87) and gel strength (r = 0.61) and negatively correlated with cooking loss (r = -0.52). Tests based on pH and L* of the P. major were also assessed; tests based on pH had a sensitivity in the range of 0.79 to 0.89 and specificity (Sp) of 0.60 to 0.94. Tests based on L* showed sensitivity of 0.75 to 0.92, and specificity of 0.79 to 0.97. The repeatability of measurements varied from good (L*: rho = 0.6) to excellent (pH: rho = 0.92). Overall, turkey breast condemned for cyanosis showed dark, firm, dry-like traits. Tests based on color and pH are described as a means of identifying turkeys condemned for cyanosis.